TUN-528: Move cloudflared into a separate repo

vendor/github.com/prometheus/client_golang/prometheus/.gitignore

@@ -0,0 +1 @@
+command-line-arguments.test

vendor/github.com/prometheus/client_golang/prometheus/README.md

@@ -0,0 +1 @@
+See [![go-doc](https://godoc.org/github.com/prometheus/client_golang/prometheus?status.svg)](https://godoc.org/github.com/prometheus/client_golang/prometheus).

vendor/github.com/prometheus/client_golang/prometheus/benchmark_test.go

@@ -0,0 +1,185 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+import (
+	"sync"
+	"testing"
+)
+
+func BenchmarkCounterWithLabelValues(b *testing.B) {
+	m := NewCounterVec(
+		CounterOpts{
+			Name: "benchmark_counter",
+			Help: "A counter to benchmark it.",
+		},
+		[]string{"one", "two", "three"},
+	)
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		m.WithLabelValues("eins", "zwei", "drei").Inc()
+	}
+}
+
+func BenchmarkCounterWithLabelValuesConcurrent(b *testing.B) {
+	m := NewCounterVec(
+		CounterOpts{
+			Name: "benchmark_counter",
+			Help: "A counter to benchmark it.",
+		},
+		[]string{"one", "two", "three"},
+	)
+	b.ReportAllocs()
+	b.ResetTimer()
+	wg := sync.WaitGroup{}
+	for i := 0; i < 10; i++ {
+		wg.Add(1)
+		go func() {
+			for j := 0; j < b.N/10; j++ {
+				m.WithLabelValues("eins", "zwei", "drei").Inc()
+			}
+			wg.Done()
+		}()
+	}
+	wg.Wait()
+}
+
+func BenchmarkCounterWithMappedLabels(b *testing.B) {
+	m := NewCounterVec(
+		CounterOpts{
+			Name: "benchmark_counter",
+			Help: "A counter to benchmark it.",
+		},
+		[]string{"one", "two", "three"},
+	)
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		m.With(Labels{"two": "zwei", "one": "eins", "three": "drei"}).Inc()
+	}
+}
+
+func BenchmarkCounterWithPreparedMappedLabels(b *testing.B) {
+	m := NewCounterVec(
+		CounterOpts{
+			Name: "benchmark_counter",
+			Help: "A counter to benchmark it.",
+		},
+		[]string{"one", "two", "three"},
+	)
+	b.ReportAllocs()
+	b.ResetTimer()
+	labels := Labels{"two": "zwei", "one": "eins", "three": "drei"}
+	for i := 0; i < b.N; i++ {
+		m.With(labels).Inc()
+	}
+}
+
+func BenchmarkCounterNoLabels(b *testing.B) {
+	m := NewCounter(CounterOpts{
+		Name: "benchmark_counter",
+		Help: "A counter to benchmark it.",
+	})
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		m.Inc()
+	}
+}
+
+func BenchmarkGaugeWithLabelValues(b *testing.B) {
+	m := NewGaugeVec(
+		GaugeOpts{
+			Name: "benchmark_gauge",
+			Help: "A gauge to benchmark it.",
+		},
+		[]string{"one", "two", "three"},
+	)
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		m.WithLabelValues("eins", "zwei", "drei").Set(3.1415)
+	}
+}
+
+func BenchmarkGaugeNoLabels(b *testing.B) {
+	m := NewGauge(GaugeOpts{
+		Name: "benchmark_gauge",
+		Help: "A gauge to benchmark it.",
+	})
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		m.Set(3.1415)
+	}
+}
+
+func BenchmarkSummaryWithLabelValues(b *testing.B) {
+	m := NewSummaryVec(
+		SummaryOpts{
+			Name:       "benchmark_summary",
+			Help:       "A summary to benchmark it.",
+			Objectives: map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001},
+		},
+		[]string{"one", "two", "three"},
+	)
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		m.WithLabelValues("eins", "zwei", "drei").Observe(3.1415)
+	}
+}
+
+func BenchmarkSummaryNoLabels(b *testing.B) {
+	m := NewSummary(SummaryOpts{
+		Name:       "benchmark_summary",
+		Help:       "A summary to benchmark it.",
+		Objectives: map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001},
+	},
+	)
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		m.Observe(3.1415)
+	}
+}
+
+func BenchmarkHistogramWithLabelValues(b *testing.B) {
+	m := NewHistogramVec(
+		HistogramOpts{
+			Name: "benchmark_histogram",
+			Help: "A histogram to benchmark it.",
+		},
+		[]string{"one", "two", "three"},
+	)
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		m.WithLabelValues("eins", "zwei", "drei").Observe(3.1415)
+	}
+}
+
+func BenchmarkHistogramNoLabels(b *testing.B) {
+	m := NewHistogram(HistogramOpts{
+		Name: "benchmark_histogram",
+		Help: "A histogram to benchmark it.",
+	},
+	)
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		m.Observe(3.1415)
+	}
+}

vendor/github.com/prometheus/client_golang/prometheus/collector.go

@@ -0,0 +1,75 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+// Collector is the interface implemented by anything that can be used by
+// Prometheus to collect metrics. A Collector has to be registered for
+// collection. See Registerer.Register.
+//
+// The stock metrics provided by this package (Gauge, Counter, Summary,
+// Histogram, Untyped) are also Collectors (which only ever collect one metric,
+// namely itself). An implementer of Collector may, however, collect multiple
+// metrics in a coordinated fashion and/or create metrics on the fly. Examples
+// for collectors already implemented in this library are the metric vectors
+// (i.e. collection of multiple instances of the same Metric but with different
+// label values) like GaugeVec or SummaryVec, and the ExpvarCollector.
+type Collector interface {
+	// Describe sends the super-set of all possible descriptors of metrics
+	// collected by this Collector to the provided channel and returns once
+	// the last descriptor has been sent. The sent descriptors fulfill the
+	// consistency and uniqueness requirements described in the Desc
+	// documentation. (It is valid if one and the same Collector sends
+	// duplicate descriptors. Those duplicates are simply ignored. However,
+	// two different Collectors must not send duplicate descriptors.) This
+	// method idempotently sends the same descriptors throughout the
+	// lifetime of the Collector. If a Collector encounters an error while
+	// executing this method, it must send an invalid descriptor (created
+	// with NewInvalidDesc) to signal the error to the registry.
+	Describe(chan<- *Desc)
+	// Collect is called by the Prometheus registry when collecting
+	// metrics. The implementation sends each collected metric via the
+	// provided channel and returns once the last metric has been sent. The
+	// descriptor of each sent metric is one of those returned by
+	// Describe. Returned metrics that share the same descriptor must differ
+	// in their variable label values. This method may be called
+	// concurrently and must therefore be implemented in a concurrency safe
+	// way. Blocking occurs at the expense of total performance of rendering
+	// all registered metrics. Ideally, Collector implementations support
+	// concurrent readers.
+	Collect(chan<- Metric)
+}
+
+// selfCollector implements Collector for a single Metric so that the Metric
+// collects itself. Add it as an anonymous field to a struct that implements
+// Metric, and call init with the Metric itself as an argument.
+type selfCollector struct {
+	self Metric
+}
+
+// init provides the selfCollector with a reference to the metric it is supposed
+// to collect. It is usually called within the factory function to create a
+// metric. See example.
+func (c *selfCollector) init(self Metric) {
+	c.self = self
+}
+
+// Describe implements Collector.
+func (c *selfCollector) Describe(ch chan<- *Desc) {
+	ch <- c.self.Desc()
+}
+
+// Collect implements Collector.
+func (c *selfCollector) Collect(ch chan<- Metric) {
+	ch <- c.self
+}

vendor/github.com/prometheus/client_golang/prometheus/counter.go

@@ -0,0 +1,189 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+import (
+	"errors"
+)
+
+// Counter is a Metric that represents a single numerical value that only ever
+// goes up. That implies that it cannot be used to count items whose number can
+// also go down, e.g. the number of currently running goroutines. Those
+// "counters" are represented by Gauges.
+//
+// A Counter is typically used to count requests served, tasks completed, errors
+// occurred, etc.
+//
+// To create Counter instances, use NewCounter.
+type Counter interface {
+	Metric
+	Collector
+
+	// Inc increments the counter by 1. Use Add to increment it by arbitrary
+	// non-negative values.
+	Inc()
+	// Add adds the given value to the counter. It panics if the value is <
+	// 0.
+	Add(float64)
+}
+
+// CounterOpts is an alias for Opts. See there for doc comments.
+type CounterOpts Opts
+
+// NewCounter creates a new Counter based on the provided CounterOpts.
+func NewCounter(opts CounterOpts) Counter {
+	desc := NewDesc(
+		BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
+		opts.Help,
+		nil,
+		opts.ConstLabels,
+	)
+	result := &counter{value: value{desc: desc, valType: CounterValue, labelPairs: desc.constLabelPairs}}
+	result.init(result) // Init self-collection.
+	return result
+}
+
+type counter struct {
+	value
+}
+
+func (c *counter) Add(v float64) {
+	if v < 0 {
+		panic(errors.New("counter cannot decrease in value"))
+	}
+	c.value.Add(v)
+}
+
+// CounterVec is a Collector that bundles a set of Counters that all share the
+// same Desc, but have different values for their variable labels. This is used
+// if you want to count the same thing partitioned by various dimensions
+// (e.g. number of HTTP requests, partitioned by response code and
+// method). Create instances with NewCounterVec.
+type CounterVec struct {
+	*metricVec
+}
+
+// NewCounterVec creates a new CounterVec based on the provided CounterOpts and
+// partitioned by the given label names.
+func NewCounterVec(opts CounterOpts, labelNames []string) *CounterVec {
+	desc := NewDesc(
+		BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
+		opts.Help,
+		labelNames,
+		opts.ConstLabels,
+	)
+	return &CounterVec{
+		metricVec: newMetricVec(desc, func(lvs ...string) Metric {
+			result := &counter{value: value{
+				desc:       desc,
+				valType:    CounterValue,
+				labelPairs: makeLabelPairs(desc, lvs),
+			}}
+			result.init(result) // Init self-collection.
+			return result
+		}),
+	}
+}
+
+// GetMetricWithLabelValues returns the Counter for the given slice of label
+// values (same order as the VariableLabels in Desc). If that combination of
+// label values is accessed for the first time, a new Counter is created.
+//
+// It is possible to call this method without using the returned Counter to only
+// create the new Counter but leave it at its starting value 0. See also the
+// SummaryVec example.
+//
+// Keeping the Counter for later use is possible (and should be considered if
+// performance is critical), but keep in mind that Reset, DeleteLabelValues and
+// Delete can be used to delete the Counter from the CounterVec. In that case,
+// the Counter will still exist, but it will not be exported anymore, even if a
+// Counter with the same label values is created later.
+//
+// An error is returned if the number of label values is not the same as the
+// number of VariableLabels in Desc.
+//
+// Note that for more than one label value, this method is prone to mistakes
+// caused by an incorrect order of arguments. Consider GetMetricWith(Labels) as
+// an alternative to avoid that type of mistake. For higher label numbers, the
+// latter has a much more readable (albeit more verbose) syntax, but it comes
+// with a performance overhead (for creating and processing the Labels map).
+// See also the GaugeVec example.
+func (m *CounterVec) GetMetricWithLabelValues(lvs ...string) (Counter, error) {
+	metric, err := m.metricVec.getMetricWithLabelValues(lvs...)
+	if metric != nil {
+		return metric.(Counter), err
+	}
+	return nil, err
+}
+
+// GetMetricWith returns the Counter for the given Labels map (the label names
+// must match those of the VariableLabels in Desc). If that label map is
+// accessed for the first time, a new Counter is created. Implications of
+// creating a Counter without using it and keeping the Counter for later use are
+// the same as for GetMetricWithLabelValues.
+//
+// An error is returned if the number and names of the Labels are inconsistent
+// with those of the VariableLabels in Desc.
+//
+// This method is used for the same purpose as
+// GetMetricWithLabelValues(...string). See there for pros and cons of the two
+// methods.
+func (m *CounterVec) GetMetricWith(labels Labels) (Counter, error) {
+	metric, err := m.metricVec.getMetricWith(labels)
+	if metric != nil {
+		return metric.(Counter), err
+	}
+	return nil, err
+}
+
+// WithLabelValues works as GetMetricWithLabelValues, but panics where
+// GetMetricWithLabelValues would have returned an error. By not returning an
+// error, WithLabelValues allows shortcuts like
+//     myVec.WithLabelValues("404", "GET").Add(42)
+func (m *CounterVec) WithLabelValues(lvs ...string) Counter {
+	return m.metricVec.withLabelValues(lvs...).(Counter)
+}
+
+// With works as GetMetricWith, but panics where GetMetricWithLabels would have
+// returned an error. By not returning an error, With allows shortcuts like
+//     myVec.With(Labels{"code": "404", "method": "GET"}).Add(42)
+func (m *CounterVec) With(labels Labels) Counter {
+	return m.metricVec.with(labels).(Counter)
+}
+
+// CounterFunc is a Counter whose value is determined at collect time by calling a
+// provided function.
+//
+// To create CounterFunc instances, use NewCounterFunc.
+type CounterFunc interface {
+	Metric
+	Collector
+}
+
+// NewCounterFunc creates a new CounterFunc based on the provided
+// CounterOpts. The value reported is determined by calling the given function
+// from within the Write method. Take into account that metric collection may
+// happen concurrently. If that results in concurrent calls to Write, like in
+// the case where a CounterFunc is directly registered with Prometheus, the
+// provided function must be concurrency-safe. The function should also honor
+// the contract for a Counter (values only go up, not down), but compliance will
+// not be checked.
+func NewCounterFunc(opts CounterOpts, function func() float64) CounterFunc {
+	return newValueFunc(NewDesc(
+		BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
+		opts.Help,
+		nil,
+		opts.ConstLabels,
+	), CounterValue, function)
+}

vendor/github.com/prometheus/client_golang/prometheus/counter_test.go

@@ -0,0 +1,114 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+import (
+	"fmt"
+	"math"
+	"testing"
+
+	dto "github.com/prometheus/client_model/go"
+)
+
+func TestCounterAdd(t *testing.T) {
+	counter := NewCounter(CounterOpts{
+		Name:        "test",
+		Help:        "test help",
+		ConstLabels: Labels{"a": "1", "b": "2"},
+	}).(*counter)
+	counter.Inc()
+	if expected, got := 1., math.Float64frombits(counter.valBits); expected != got {
+		t.Errorf("Expected %f, got %f.", expected, got)
+	}
+	counter.Add(42)
+	if expected, got := 43., math.Float64frombits(counter.valBits); expected != got {
+		t.Errorf("Expected %f, got %f.", expected, got)
+	}
+
+	if expected, got := "counter cannot decrease in value", decreaseCounter(counter).Error(); expected != got {
+		t.Errorf("Expected error %q, got %q.", expected, got)
+	}
+
+	m := &dto.Metric{}
+	counter.Write(m)
+
+	if expected, got := `label:<name:"a" value:"1" > label:<name:"b" value:"2" > counter:<value:43 > `, m.String(); expected != got {
+		t.Errorf("expected %q, got %q", expected, got)
+	}
+}
+
+func decreaseCounter(c *counter) (err error) {
+	defer func() {
+		if e := recover(); e != nil {
+			err = e.(error)
+		}
+	}()
+	c.Add(-1)
+	return nil
+}
+
+func TestCounterVecGetMetricWithInvalidLabelValues(t *testing.T) {
+	testCases := []struct {
+		desc   string
+		labels Labels
+	}{
+		{
+			desc:   "non utf8 label value",
+			labels: Labels{"a": "\xFF"},
+		},
+		{
+			desc:   "not enough label values",
+			labels: Labels{},
+		},
+		{
+			desc:   "too many label values",
+			labels: Labels{"a": "1", "b": "2"},
+		},
+	}
+
+	for _, test := range testCases {
+		counterVec := NewCounterVec(CounterOpts{
+			Name: "test",
+		}, []string{"a"})
+
+		labelValues := make([]string, len(test.labels))
+		for _, val := range test.labels {
+			labelValues = append(labelValues, val)
+		}
+
+		expectPanic(t, func() {
+			counterVec.WithLabelValues(labelValues...)
+		}, fmt.Sprintf("WithLabelValues: expected panic because: %s", test.desc))
+		expectPanic(t, func() {
+			counterVec.With(test.labels)
+		}, fmt.Sprintf("WithLabelValues: expected panic because: %s", test.desc))
+
+		if _, err := counterVec.GetMetricWithLabelValues(labelValues...); err == nil {
+			t.Errorf("GetMetricWithLabelValues: expected error because: %s", test.desc)
+		}
+		if _, err := counterVec.GetMetricWith(test.labels); err == nil {
+			t.Errorf("GetMetricWith: expected error because: %s", test.desc)
+		}
+	}
+}
+
+func expectPanic(t *testing.T, op func(), errorMsg string) {
+	defer func() {
+		if err := recover(); err == nil {
+			t.Error(errorMsg)
+		}
+	}()
+
+	op()
+}

vendor/github.com/prometheus/client_golang/prometheus/desc.go

@@ -0,0 +1,189 @@
+// Copyright 2016 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+import (
+	"errors"
+	"fmt"
+	"sort"
+	"strings"
+
+	"github.com/golang/protobuf/proto"
+	"github.com/prometheus/common/model"
+
+	dto "github.com/prometheus/client_model/go"
+)
+
+// Desc is the descriptor used by every Prometheus Metric. It is essentially
+// the immutable meta-data of a Metric. The normal Metric implementations
+// included in this package manage their Desc under the hood. Users only have to
+// deal with Desc if they use advanced features like the ExpvarCollector or
+// custom Collectors and Metrics.
+//
+// Descriptors registered with the same registry have to fulfill certain
+// consistency and uniqueness criteria if they share the same fully-qualified
+// name: They must have the same help string and the same label names (aka label
+// dimensions) in each, constLabels and variableLabels, but they must differ in
+// the values of the constLabels.
+//
+// Descriptors that share the same fully-qualified names and the same label
+// values of their constLabels are considered equal.
+//
+// Use NewDesc to create new Desc instances.
+type Desc struct {
+	// fqName has been built from Namespace, Subsystem, and Name.
+	fqName string
+	// help provides some helpful information about this metric.
+	help string
+	// constLabelPairs contains precalculated DTO label pairs based on
+	// the constant labels.
+	constLabelPairs []*dto.LabelPair
+	// VariableLabels contains names of labels for which the metric
+	// maintains variable values.
+	variableLabels []string
+	// id is a hash of the values of the ConstLabels and fqName. This
+	// must be unique among all registered descriptors and can therefore be
+	// used as an identifier of the descriptor.
+	id uint64
+	// dimHash is a hash of the label names (preset and variable) and the
+	// Help string. Each Desc with the same fqName must have the same
+	// dimHash.
+	dimHash uint64
+	// err is an error that occurred during construction. It is reported on
+	// registration time.
+	err error
+}
+
+// NewDesc allocates and initializes a new Desc. Errors are recorded in the Desc
+// and will be reported on registration time. variableLabels and constLabels can
+// be nil if no such labels should be set. fqName and help must not be empty.
+//
+// variableLabels only contain the label names. Their label values are variable
+// and therefore not part of the Desc. (They are managed within the Metric.)
+//
+// For constLabels, the label values are constant. Therefore, they are fully
+// specified in the Desc. See the Opts documentation for the implications of
+// constant labels.
+func NewDesc(fqName, help string, variableLabels []string, constLabels Labels) *Desc {
+	d := &Desc{
+		fqName:         fqName,
+		help:           help,
+		variableLabels: variableLabels,
+	}
+	if help == "" {
+		d.err = errors.New("empty help string")
+		return d
+	}
+	if !model.IsValidMetricName(model.LabelValue(fqName)) {
+		d.err = fmt.Errorf("%q is not a valid metric name", fqName)
+		return d
+	}
+	// labelValues contains the label values of const labels (in order of
+	// their sorted label names) plus the fqName (at position 0).
+	labelValues := make([]string, 1, len(constLabels)+1)
+	labelValues[0] = fqName
+	labelNames := make([]string, 0, len(constLabels)+len(variableLabels))
+	labelNameSet := map[string]struct{}{}
+	// First add only the const label names and sort them...
+	for labelName := range constLabels {
+		if !checkLabelName(labelName) {
+			d.err = fmt.Errorf("%q is not a valid label name", labelName)
+			return d
+		}
+		labelNames = append(labelNames, labelName)
+		labelNameSet[labelName] = struct{}{}
+	}
+	sort.Strings(labelNames)
+	// ... so that we can now add const label values in the order of their names.
+	for _, labelName := range labelNames {
+		labelValues = append(labelValues, constLabels[labelName])
+	}
+	// Validate the const label values. They can't have a wrong cardinality, so
+	// use in len(labelValues) as expectedNumberOfValues.
+	if err := validateLabelValues(labelValues, len(labelValues)); err != nil {
+		d.err = err
+		return d
+	}
+	// Now add the variable label names, but prefix them with something that
+	// cannot be in a regular label name. That prevents matching the label
+	// dimension with a different mix between preset and variable labels.
+	for _, labelName := range variableLabels {
+		if !checkLabelName(labelName) {
+			d.err = fmt.Errorf("%q is not a valid label name", labelName)
+			return d
+		}
+		labelNames = append(labelNames, "$"+labelName)
+		labelNameSet[labelName] = struct{}{}
+	}
+	if len(labelNames) != len(labelNameSet) {
+		d.err = errors.New("duplicate label names")
+		return d
+	}
+
+	vh := hashNew()
+	for _, val := range labelValues {
+		vh = hashAdd(vh, val)
+		vh = hashAddByte(vh, separatorByte)
+	}
+	d.id = vh
+	// Sort labelNames so that order doesn't matter for the hash.
+	sort.Strings(labelNames)
+	// Now hash together (in this order) the help string and the sorted
+	// label names.
+	lh := hashNew()
+	lh = hashAdd(lh, help)
+	lh = hashAddByte(lh, separatorByte)
+	for _, labelName := range labelNames {
+		lh = hashAdd(lh, labelName)
+		lh = hashAddByte(lh, separatorByte)
+	}
+	d.dimHash = lh
+
+	d.constLabelPairs = make([]*dto.LabelPair, 0, len(constLabels))
+	for n, v := range constLabels {
+		d.constLabelPairs = append(d.constLabelPairs, &dto.LabelPair{
+			Name:  proto.String(n),
+			Value: proto.String(v),
+		})
+	}
+	sort.Sort(LabelPairSorter(d.constLabelPairs))
+	return d
+}
+
+// NewInvalidDesc returns an invalid descriptor, i.e. a descriptor with the
+// provided error set. If a collector returning such a descriptor is registered,
+// registration will fail with the provided error. NewInvalidDesc can be used by
+// a Collector to signal inability to describe itself.
+func NewInvalidDesc(err error) *Desc {
+	return &Desc{
+		err: err,
+	}
+}
+
+func (d *Desc) String() string {
+	lpStrings := make([]string, 0, len(d.constLabelPairs))
+	for _, lp := range d.constLabelPairs {
+		lpStrings = append(
+			lpStrings,
+			fmt.Sprintf("%s=%q", lp.GetName(), lp.GetValue()),
+		)
+	}
+	return fmt.Sprintf(
+		"Desc{fqName: %q, help: %q, constLabels: {%s}, variableLabels: %v}",
+		d.fqName,
+		d.help,
+		strings.Join(lpStrings, ","),
+		d.variableLabels,
+	)
+}

vendor/github.com/prometheus/client_golang/prometheus/desc_test.go

@@ -0,0 +1,17 @@
+package prometheus
+
+import (
+	"testing"
+)
+
+func TestNewDescInvalidLabelValues(t *testing.T) {
+	desc := NewDesc(
+		"sample_label",
+		"sample label",
+		nil,
+		Labels{"a": "\xFF"},
+	)
+	if desc.err == nil {
+		t.Errorf("NewDesc: expected error because: %s", desc.err)
+	}
+}

vendor/github.com/prometheus/client_golang/prometheus/doc.go

@@ -0,0 +1,186 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package prometheus provides metrics primitives to instrument code for
+// monitoring. It also offers a registry for metrics. Sub-packages allow to
+// expose the registered metrics via HTTP (package promhttp) or push them to a
+// Pushgateway (package push).
+//
+// All exported functions and methods are safe to be used concurrently unless
+// specified otherwise.
+//
+// A Basic Example
+//
+// As a starting point, a very basic usage example:
+//
+//    package main
+//
+//    import (
+//    	"log"
+//    	"net/http"
+//
+//    	"github.com/prometheus/client_golang/prometheus"
+//    	"github.com/prometheus/client_golang/prometheus/promhttp"
+//    )
+//
+//    var (
+//    	cpuTemp = prometheus.NewGauge(prometheus.GaugeOpts{
+//    		Name: "cpu_temperature_celsius",
+//    		Help: "Current temperature of the CPU.",
+//    	})
+//    	hdFailures = prometheus.NewCounterVec(
+//    		prometheus.CounterOpts{
+//    			Name: "hd_errors_total",
+//    			Help: "Number of hard-disk errors.",
+//    		},
+//    		[]string{"device"},
+//    	)
+//    )
+//
+//    func init() {
+//    	// Metrics have to be registered to be exposed:
+//    	prometheus.MustRegister(cpuTemp)
+//    	prometheus.MustRegister(hdFailures)
+//    }
+//
+//    func main() {
+//    	cpuTemp.Set(65.3)
+//    	hdFailures.With(prometheus.Labels{"device":"/dev/sda"}).Inc()
+//
+//    	// The Handler function provides a default handler to expose metrics
+//    	// via an HTTP server. "/metrics" is the usual endpoint for that.
+//    	http.Handle("/metrics", promhttp.Handler())
+//    	log.Fatal(http.ListenAndServe(":8080", nil))
+//    }
+//
+//
+// This is a complete program that exports two metrics, a Gauge and a Counter,
+// the latter with a label attached to turn it into a (one-dimensional) vector.
+//
+// Metrics
+//
+// The number of exported identifiers in this package might appear a bit
+// overwhelming. However, in addition to the basic plumbing shown in the example
+// above, you only need to understand the different metric types and their
+// vector versions for basic usage.
+//
+// Above, you have already touched the Counter and the Gauge. There are two more
+// advanced metric types: the Summary and Histogram. A more thorough description
+// of those four metric types can be found in the Prometheus docs:
+// https://prometheus.io/docs/concepts/metric_types/
+//
+// A fifth "type" of metric is Untyped. It behaves like a Gauge, but signals the
+// Prometheus server not to assume anything about its type.
+//
+// In addition to the fundamental metric types Gauge, Counter, Summary,
+// Histogram, and Untyped, a very important part of the Prometheus data model is
+// the partitioning of samples along dimensions called labels, which results in
+// metric vectors. The fundamental types are GaugeVec, CounterVec, SummaryVec,
+// HistogramVec, and UntypedVec.
+//
+// While only the fundamental metric types implement the Metric interface, both
+// the metrics and their vector versions implement the Collector interface. A
+// Collector manages the collection of a number of Metrics, but for convenience,
+// a Metric can also “collect itself”. Note that Gauge, Counter, Summary,
+// Histogram, and Untyped are interfaces themselves while GaugeVec, CounterVec,
+// SummaryVec, HistogramVec, and UntypedVec are not.
+//
+// To create instances of Metrics and their vector versions, you need a suitable
+// …Opts struct, i.e. GaugeOpts, CounterOpts, SummaryOpts, HistogramOpts, or
+// UntypedOpts.
+//
+// Custom Collectors and constant Metrics
+//
+// While you could create your own implementations of Metric, most likely you
+// will only ever implement the Collector interface on your own. At a first
+// glance, a custom Collector seems handy to bundle Metrics for common
+// registration (with the prime example of the different metric vectors above,
+// which bundle all the metrics of the same name but with different labels).
+//
+// There is a more involved use case, too: If you already have metrics
+// available, created outside of the Prometheus context, you don't need the
+// interface of the various Metric types. You essentially want to mirror the
+// existing numbers into Prometheus Metrics during collection. An own
+// implementation of the Collector interface is perfect for that. You can create
+// Metric instances “on the fly” using NewConstMetric, NewConstHistogram, and
+// NewConstSummary (and their respective Must… versions). That will happen in
+// the Collect method. The Describe method has to return separate Desc
+// instances, representative of the “throw-away” metrics to be created later.
+// NewDesc comes in handy to create those Desc instances.
+//
+// The Collector example illustrates the use case. You can also look at the
+// source code of the processCollector (mirroring process metrics), the
+// goCollector (mirroring Go metrics), or the expvarCollector (mirroring expvar
+// metrics) as examples that are used in this package itself.
+//
+// If you just need to call a function to get a single float value to collect as
+// a metric, GaugeFunc, CounterFunc, or UntypedFunc might be interesting
+// shortcuts.
+//
+// Advanced Uses of the Registry
+//
+// While MustRegister is the by far most common way of registering a Collector,
+// sometimes you might want to handle the errors the registration might cause.
+// As suggested by the name, MustRegister panics if an error occurs. With the
+// Register function, the error is returned and can be handled.
+//
+// An error is returned if the registered Collector is incompatible or
+// inconsistent with already registered metrics. The registry aims for
+// consistency of the collected metrics according to the Prometheus data model.
+// Inconsistencies are ideally detected at registration time, not at collect
+// time. The former will usually be detected at start-up time of a program,
+// while the latter will only happen at scrape time, possibly not even on the
+// first scrape if the inconsistency only becomes relevant later. That is the
+// main reason why a Collector and a Metric have to describe themselves to the
+// registry.
+//
+// So far, everything we did operated on the so-called default registry, as it
+// can be found in the global DefaultRegistry variable. With NewRegistry, you
+// can create a custom registry, or you can even implement the Registerer or
+// Gatherer interfaces yourself. The methods Register and Unregister work in the
+// same way on a custom registry as the global functions Register and Unregister
+// on the default registry.
+//
+// There are a number of uses for custom registries: You can use registries with
+// special properties, see NewPedanticRegistry. You can avoid global state, as
+// it is imposed by the DefaultRegistry. You can use multiple registries at the
+// same time to expose different metrics in different ways. You can use separate
+// registries for testing purposes.
+//
+// Also note that the DefaultRegistry comes registered with a Collector for Go
+// runtime metrics (via NewGoCollector) and a Collector for process metrics (via
+// NewProcessCollector). With a custom registry, you are in control and decide
+// yourself about the Collectors to register.
+//
+// HTTP Exposition
+//
+// The Registry implements the Gatherer interface. The caller of the Gather
+// method can then expose the gathered metrics in some way. Usually, the metrics
+// are served via HTTP on the /metrics endpoint. That's happening in the example
+// above. The tools to expose metrics via HTTP are in the promhttp sub-package.
+// (The top-level functions in the prometheus package are deprecated.)
+//
+// Pushing to the Pushgateway
+//
+// Function for pushing to the Pushgateway can be found in the push sub-package.
+//
+// Graphite Bridge
+//
+// Functions and examples to push metrics from a Gatherer to Graphite can be
+// found in the graphite sub-package.
+//
+// Other Means of Exposition
+//
+// More ways of exposing metrics can easily be added by following the approaches
+// of the existing implementations.
+package prometheus

vendor/github.com/prometheus/client_golang/prometheus/example_clustermanager_test.go

@@ -0,0 +1,118 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus_test
+
+import "github.com/prometheus/client_golang/prometheus"
+
+// ClusterManager is an example for a system that might have been built without
+// Prometheus in mind. It models a central manager of jobs running in a
+// cluster. To turn it into something that collects Prometheus metrics, we
+// simply add the two methods required for the Collector interface.
+//
+// An additional challenge is that multiple instances of the ClusterManager are
+// run within the same binary, each in charge of a different zone. We need to
+// make use of ConstLabels to be able to register each ClusterManager instance
+// with Prometheus.
+type ClusterManager struct {
+	Zone         string
+	OOMCountDesc *prometheus.Desc
+	RAMUsageDesc *prometheus.Desc
+	// ... many more fields
+}
+
+// ReallyExpensiveAssessmentOfTheSystemState is a mock for the data gathering a
+// real cluster manager would have to do. Since it may actually be really
+// expensive, it must only be called once per collection. This implementation,
+// obviously, only returns some made-up data.
+func (c *ClusterManager) ReallyExpensiveAssessmentOfTheSystemState() (
+	oomCountByHost map[string]int, ramUsageByHost map[string]float64,
+) {
+	// Just example fake data.
+	oomCountByHost = map[string]int{
+		"foo.example.org": 42,
+		"bar.example.org": 2001,
+	}
+	ramUsageByHost = map[string]float64{
+		"foo.example.org": 6.023e23,
+		"bar.example.org": 3.14,
+	}
+	return
+}
+
+// Describe simply sends the two Descs in the struct to the channel.
+func (c *ClusterManager) Describe(ch chan<- *prometheus.Desc) {
+	ch <- c.OOMCountDesc
+	ch <- c.RAMUsageDesc
+}
+
+// Collect first triggers the ReallyExpensiveAssessmentOfTheSystemState. Then it
+// creates constant metrics for each host on the fly based on the returned data.
+//
+// Note that Collect could be called concurrently, so we depend on
+// ReallyExpensiveAssessmentOfTheSystemState to be concurrency-safe.
+func (c *ClusterManager) Collect(ch chan<- prometheus.Metric) {
+	oomCountByHost, ramUsageByHost := c.ReallyExpensiveAssessmentOfTheSystemState()
+	for host, oomCount := range oomCountByHost {
+		ch <- prometheus.MustNewConstMetric(
+			c.OOMCountDesc,
+			prometheus.CounterValue,
+			float64(oomCount),
+			host,
+		)
+	}
+	for host, ramUsage := range ramUsageByHost {
+		ch <- prometheus.MustNewConstMetric(
+			c.RAMUsageDesc,
+			prometheus.GaugeValue,
+			ramUsage,
+			host,
+		)
+	}
+}
+
+// NewClusterManager creates the two Descs OOMCountDesc and RAMUsageDesc. Note
+// that the zone is set as a ConstLabel. (It's different in each instance of the
+// ClusterManager, but constant over the lifetime of an instance.) Then there is
+// a variable label "host", since we want to partition the collected metrics by
+// host. Since all Descs created in this way are consistent across instances,
+// with a guaranteed distinction by the "zone" label, we can register different
+// ClusterManager instances with the same registry.
+func NewClusterManager(zone string) *ClusterManager {
+	return &ClusterManager{
+		Zone: zone,
+		OOMCountDesc: prometheus.NewDesc(
+			"clustermanager_oom_crashes_total",
+			"Number of OOM crashes.",
+			[]string{"host"},
+			prometheus.Labels{"zone": zone},
+		),
+		RAMUsageDesc: prometheus.NewDesc(
+			"clustermanager_ram_usage_bytes",
+			"RAM usage as reported to the cluster manager.",
+			[]string{"host"},
+			prometheus.Labels{"zone": zone},
+		),
+	}
+}
+
+func ExampleCollector() {
+	workerDB := NewClusterManager("db")
+	workerCA := NewClusterManager("ca")
+
+	// Since we are dealing with custom Collector implementations, it might
+	// be a good idea to try it out with a pedantic registry.
+	reg := prometheus.NewPedanticRegistry()
+	reg.MustRegister(workerDB)
+	reg.MustRegister(workerCA)
+}

vendor/github.com/prometheus/client_golang/prometheus/example_timer_complex_test.go

@@ -0,0 +1,71 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus_test
+
+import (
+	"net/http"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+var (
+	// apiRequestDuration tracks the duration separate for each HTTP status
+	// class (1xx, 2xx, ...). This creates a fair amount of time series on
+	// the Prometheus server. Usually, you would track the duration of
+	// serving HTTP request without partitioning by outcome. Do something
+	// like this only if needed. Also note how only status classes are
+	// tracked, not every single status code. The latter would create an
+	// even larger amount of time series. Request counters partitioned by
+	// status code are usually OK as each counter only creates one time
+	// series. Histograms are way more expensive, so partition with care and
+	// only where you really need separate latency tracking. Partitioning by
+	// status class is only an example. In concrete cases, other partitions
+	// might make more sense.
+	apiRequestDuration = prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name:    "api_request_duration_seconds",
+			Help:    "Histogram for the request duration of the public API, partitioned by status class.",
+			Buckets: prometheus.ExponentialBuckets(0.1, 1.5, 5),
+		},
+		[]string{"status_class"},
+	)
+)
+
+func handler(w http.ResponseWriter, r *http.Request) {
+	status := http.StatusOK
+	// The ObserverFunc gets called by the deferred ObserveDuration and
+	// decides which Histogram's Observe method is called.
+	timer := prometheus.NewTimer(prometheus.ObserverFunc(func(v float64) {
+		switch {
+		case status >= 500: // Server error.
+			apiRequestDuration.WithLabelValues("5xx").Observe(v)
+		case status >= 400: // Client error.
+			apiRequestDuration.WithLabelValues("4xx").Observe(v)
+		case status >= 300: // Redirection.
+			apiRequestDuration.WithLabelValues("3xx").Observe(v)
+		case status >= 200: // Success.
+			apiRequestDuration.WithLabelValues("2xx").Observe(v)
+		default: // Informational.
+			apiRequestDuration.WithLabelValues("1xx").Observe(v)
+		}
+	}))
+	defer timer.ObserveDuration()
+
+	// Handle the request. Set status accordingly.
+	// ...
+}
+
+func ExampleTimer_complex() {
+	http.HandleFunc("/api", handler)
+}

vendor/github.com/prometheus/client_golang/prometheus/example_timer_gauge_test.go

@@ -0,0 +1,48 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus_test
+
+import (
+	"os"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+var (
+	// If a function is called rarely (i.e. not more often than scrapes
+	// happen) or ideally only once (like in a batch job), it can make sense
+	// to use a Gauge for timing the function call. For timing a batch job
+	// and pushing the result to a Pushgateway, see also the comprehensive
+	// example in the push package.
+	funcDuration = prometheus.NewGauge(prometheus.GaugeOpts{
+		Name: "example_function_duration_seconds",
+		Help: "Duration of the last call of an example function.",
+	})
+)
+
+func run() error {
+	// The Set method of the Gauge is used to observe the duration.
+	timer := prometheus.NewTimer(prometheus.ObserverFunc(funcDuration.Set))
+	defer timer.ObserveDuration()
+
+	// Do something. Return errors as encountered. The use of 'defer' above
+	// makes sure the function is still timed properly.
+	return nil
+}
+
+func ExampleTimer_gauge() {
+	if err := run(); err != nil {
+		os.Exit(1)
+	}
+}

vendor/github.com/prometheus/client_golang/prometheus/example_timer_test.go

@@ -0,0 +1,40 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus_test
+
+import (
+	"math/rand"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+var (
+	requestDuration = prometheus.NewHistogram(prometheus.HistogramOpts{
+		Name:    "example_request_duration_seconds",
+		Help:    "Histogram for the runtime of a simple example function.",
+		Buckets: prometheus.LinearBuckets(0.01, 0.01, 10),
+	})
+)
+
+func ExampleTimer() {
+	// timer times this example function. It uses a Histogram, but a Summary
+	// would also work, as both implement Observer. Check out
+	// https://prometheus.io/docs/practices/histograms/ for differences.
+	timer := prometheus.NewTimer(requestDuration)
+	defer timer.ObserveDuration()
+
+	// Do something here that takes time.
+	time.Sleep(time.Duration(rand.NormFloat64()*10000+50000) * time.Microsecond)
+}

vendor/github.com/prometheus/client_golang/prometheus/examples_test.go

@@ -0,0 +1,754 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus_test
+
+import (
+	"bytes"
+	"fmt"
+	"math"
+	"net/http"
+	"runtime"
+	"sort"
+	"strings"
+
+	dto "github.com/prometheus/client_model/go"
+	"github.com/prometheus/common/expfmt"
+
+	"github.com/golang/protobuf/proto"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+func ExampleGauge() {
+	opsQueued := prometheus.NewGauge(prometheus.GaugeOpts{
+		Namespace: "our_company",
+		Subsystem: "blob_storage",
+		Name:      "ops_queued",
+		Help:      "Number of blob storage operations waiting to be processed.",
+	})
+	prometheus.MustRegister(opsQueued)
+
+	// 10 operations queued by the goroutine managing incoming requests.
+	opsQueued.Add(10)
+	// A worker goroutine has picked up a waiting operation.
+	opsQueued.Dec()
+	// And once more...
+	opsQueued.Dec()
+}
+
+func ExampleGaugeVec() {
+	opsQueued := prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Namespace: "our_company",
+			Subsystem: "blob_storage",
+			Name:      "ops_queued",
+			Help:      "Number of blob storage operations waiting to be processed, partitioned by user and type.",
+		},
+		[]string{
+			// Which user has requested the operation?
+			"user",
+			// Of what type is the operation?
+			"type",
+		},
+	)
+	prometheus.MustRegister(opsQueued)
+
+	// Increase a value using compact (but order-sensitive!) WithLabelValues().
+	opsQueued.WithLabelValues("bob", "put").Add(4)
+	// Increase a value with a map using WithLabels. More verbose, but order
+	// doesn't matter anymore.
+	opsQueued.With(prometheus.Labels{"type": "delete", "user": "alice"}).Inc()
+}
+
+func ExampleGaugeFunc() {
+	if err := prometheus.Register(prometheus.NewGaugeFunc(
+		prometheus.GaugeOpts{
+			Subsystem: "runtime",
+			Name:      "goroutines_count",
+			Help:      "Number of goroutines that currently exist.",
+		},
+		func() float64 { return float64(runtime.NumGoroutine()) },
+	)); err == nil {
+		fmt.Println("GaugeFunc 'goroutines_count' registered.")
+	}
+	// Note that the count of goroutines is a gauge (and not a counter) as
+	// it can go up and down.
+
+	// Output:
+	// GaugeFunc 'goroutines_count' registered.
+}
+
+func ExampleCounter() {
+	pushCounter := prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "repository_pushes", // Note: No help string...
+	})
+	err := prometheus.Register(pushCounter) // ... so this will return an error.
+	if err != nil {
+		fmt.Println("Push counter couldn't be registered, no counting will happen:", err)
+		return
+	}
+
+	// Try it once more, this time with a help string.
+	pushCounter = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "repository_pushes",
+		Help: "Number of pushes to external repository.",
+	})
+	err = prometheus.Register(pushCounter)
+	if err != nil {
+		fmt.Println("Push counter couldn't be registered AGAIN, no counting will happen:", err)
+		return
+	}
+
+	pushComplete := make(chan struct{})
+	// TODO: Start a goroutine that performs repository pushes and reports
+	// each completion via the channel.
+	for range pushComplete {
+		pushCounter.Inc()
+	}
+	// Output:
+	// Push counter couldn't be registered, no counting will happen: descriptor Desc{fqName: "repository_pushes", help: "", constLabels: {}, variableLabels: []} is invalid: empty help string
+}
+
+func ExampleCounterVec() {
+	httpReqs := prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "http_requests_total",
+			Help: "How many HTTP requests processed, partitioned by status code and HTTP method.",
+		},
+		[]string{"code", "method"},
+	)
+	prometheus.MustRegister(httpReqs)
+
+	httpReqs.WithLabelValues("404", "POST").Add(42)
+
+	// If you have to access the same set of labels very frequently, it
+	// might be good to retrieve the metric only once and keep a handle to
+	// it. But beware of deletion of that metric, see below!
+	m := httpReqs.WithLabelValues("200", "GET")
+	for i := 0; i < 1000000; i++ {
+		m.Inc()
+	}
+	// Delete a metric from the vector. If you have previously kept a handle
+	// to that metric (as above), future updates via that handle will go
+	// unseen (even if you re-create a metric with the same label set
+	// later).
+	httpReqs.DeleteLabelValues("200", "GET")
+	// Same thing with the more verbose Labels syntax.
+	httpReqs.Delete(prometheus.Labels{"method": "GET", "code": "200"})
+}
+
+func ExampleInstrumentHandler() {
+	// Handle the "/doc" endpoint with the standard http.FileServer handler.
+	// By wrapping the handler with InstrumentHandler, request count,
+	// request and response sizes, and request latency are automatically
+	// exported to Prometheus, partitioned by HTTP status code and method
+	// and by the handler name (here "fileserver").
+	http.Handle("/doc", prometheus.InstrumentHandler(
+		"fileserver", http.FileServer(http.Dir("/usr/share/doc")),
+	))
+	// The Prometheus handler still has to be registered to handle the
+	// "/metrics" endpoint. The handler returned by prometheus.Handler() is
+	// already instrumented - with "prometheus" as the handler name. In this
+	// example, we want the handler name to be "metrics", so we instrument
+	// the uninstrumented Prometheus handler ourselves.
+	http.Handle("/metrics", prometheus.InstrumentHandler(
+		"metrics", prometheus.UninstrumentedHandler(),
+	))
+}
+
+func ExampleLabelPairSorter() {
+	labelPairs := []*dto.LabelPair{
+		{Name: proto.String("status"), Value: proto.String("404")},
+		{Name: proto.String("method"), Value: proto.String("get")},
+	}
+
+	sort.Sort(prometheus.LabelPairSorter(labelPairs))
+
+	fmt.Println(labelPairs)
+	// Output:
+	// [name:"method" value:"get"  name:"status" value:"404" ]
+}
+
+func ExampleRegister() {
+	// Imagine you have a worker pool and want to count the tasks completed.
+	taskCounter := prometheus.NewCounter(prometheus.CounterOpts{
+		Subsystem: "worker_pool",
+		Name:      "completed_tasks_total",
+		Help:      "Total number of tasks completed.",
+	})
+	// This will register fine.
+	if err := prometheus.Register(taskCounter); err != nil {
+		fmt.Println(err)
+	} else {
+		fmt.Println("taskCounter registered.")
+	}
+	// Don't forget to tell the HTTP server about the Prometheus handler.
+	// (In a real program, you still need to start the HTTP server...)
+	http.Handle("/metrics", prometheus.Handler())
+
+	// Now you can start workers and give every one of them a pointer to
+	// taskCounter and let it increment it whenever it completes a task.
+	taskCounter.Inc() // This has to happen somewhere in the worker code.
+
+	// But wait, you want to see how individual workers perform. So you need
+	// a vector of counters, with one element for each worker.
+	taskCounterVec := prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Subsystem: "worker_pool",
+			Name:      "completed_tasks_total",
+			Help:      "Total number of tasks completed.",
+		},
+		[]string{"worker_id"},
+	)
+
+	// Registering will fail because we already have a metric of that name.
+	if err := prometheus.Register(taskCounterVec); err != nil {
+		fmt.Println("taskCounterVec not registered:", err)
+	} else {
+		fmt.Println("taskCounterVec registered.")
+	}
+
+	// To fix, first unregister the old taskCounter.
+	if prometheus.Unregister(taskCounter) {
+		fmt.Println("taskCounter unregistered.")
+	}
+
+	// Try registering taskCounterVec again.
+	if err := prometheus.Register(taskCounterVec); err != nil {
+		fmt.Println("taskCounterVec not registered:", err)
+	} else {
+		fmt.Println("taskCounterVec registered.")
+	}
+	// Bummer! Still doesn't work.
+
+	// Prometheus will not allow you to ever export metrics with
+	// inconsistent help strings or label names. After unregistering, the
+	// unregistered metrics will cease to show up in the /metrics HTTP
+	// response, but the registry still remembers that those metrics had
+	// been exported before. For this example, we will now choose a
+	// different name. (In a real program, you would obviously not export
+	// the obsolete metric in the first place.)
+	taskCounterVec = prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Subsystem: "worker_pool",
+			Name:      "completed_tasks_by_id",
+			Help:      "Total number of tasks completed.",
+		},
+		[]string{"worker_id"},
+	)
+	if err := prometheus.Register(taskCounterVec); err != nil {
+		fmt.Println("taskCounterVec not registered:", err)
+	} else {
+		fmt.Println("taskCounterVec registered.")
+	}
+	// Finally it worked!
+
+	// The workers have to tell taskCounterVec their id to increment the
+	// right element in the metric vector.
+	taskCounterVec.WithLabelValues("42").Inc() // Code from worker 42.
+
+	// Each worker could also keep a reference to their own counter element
+	// around. Pick the counter at initialization time of the worker.
+	myCounter := taskCounterVec.WithLabelValues("42") // From worker 42 initialization code.
+	myCounter.Inc()                                   // Somewhere in the code of that worker.
+
+	// Note that something like WithLabelValues("42", "spurious arg") would
+	// panic (because you have provided too many label values). If you want
+	// to get an error instead, use GetMetricWithLabelValues(...) instead.
+	notMyCounter, err := taskCounterVec.GetMetricWithLabelValues("42", "spurious arg")
+	if err != nil {
+		fmt.Println("Worker initialization failed:", err)
+	}
+	if notMyCounter == nil {
+		fmt.Println("notMyCounter is nil.")
+	}
+
+	// A different (and somewhat tricky) approach is to use
+	// ConstLabels. ConstLabels are pairs of label names and label values
+	// that never change. You might ask what those labels are good for (and
+	// rightfully so - if they never change, they could as well be part of
+	// the metric name). There are essentially two use-cases: The first is
+	// if labels are constant throughout the lifetime of a binary execution,
+	// but they vary over time or between different instances of a running
+	// binary. The second is what we have here: Each worker creates and
+	// registers an own Counter instance where the only difference is in the
+	// value of the ConstLabels. Those Counters can all be registered
+	// because the different ConstLabel values guarantee that each worker
+	// will increment a different Counter metric.
+	counterOpts := prometheus.CounterOpts{
+		Subsystem:   "worker_pool",
+		Name:        "completed_tasks",
+		Help:        "Total number of tasks completed.",
+		ConstLabels: prometheus.Labels{"worker_id": "42"},
+	}
+	taskCounterForWorker42 := prometheus.NewCounter(counterOpts)
+	if err := prometheus.Register(taskCounterForWorker42); err != nil {
+		fmt.Println("taskCounterVForWorker42 not registered:", err)
+	} else {
+		fmt.Println("taskCounterForWorker42 registered.")
+	}
+	// Obviously, in real code, taskCounterForWorker42 would be a member
+	// variable of a worker struct, and the "42" would be retrieved with a
+	// GetId() method or something. The Counter would be created and
+	// registered in the initialization code of the worker.
+
+	// For the creation of the next Counter, we can recycle
+	// counterOpts. Just change the ConstLabels.
+	counterOpts.ConstLabels = prometheus.Labels{"worker_id": "2001"}
+	taskCounterForWorker2001 := prometheus.NewCounter(counterOpts)
+	if err := prometheus.Register(taskCounterForWorker2001); err != nil {
+		fmt.Println("taskCounterVForWorker2001 not registered:", err)
+	} else {
+		fmt.Println("taskCounterForWorker2001 registered.")
+	}
+
+	taskCounterForWorker2001.Inc()
+	taskCounterForWorker42.Inc()
+	taskCounterForWorker2001.Inc()
+
+	// Yet another approach would be to turn the workers themselves into
+	// Collectors and register them. See the Collector example for details.
+
+	// Output:
+	// taskCounter registered.
+	// taskCounterVec not registered: a previously registered descriptor with the same fully-qualified name as Desc{fqName: "worker_pool_completed_tasks_total", help: "Total number of tasks completed.", constLabels: {}, variableLabels: [worker_id]} has different label names or a different help string
+	// taskCounter unregistered.
+	// taskCounterVec not registered: a previously registered descriptor with the same fully-qualified name as Desc{fqName: "worker_pool_completed_tasks_total", help: "Total number of tasks completed.", constLabels: {}, variableLabels: [worker_id]} has different label names or a different help string
+	// taskCounterVec registered.
+	// Worker initialization failed: inconsistent label cardinality
+	// notMyCounter is nil.
+	// taskCounterForWorker42 registered.
+	// taskCounterForWorker2001 registered.
+}
+
+func ExampleSummary() {
+	temps := prometheus.NewSummary(prometheus.SummaryOpts{
+		Name:       "pond_temperature_celsius",
+		Help:       "The temperature of the frog pond.",
+		Objectives: map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001},
+	})
+
+	// Simulate some observations.
+	for i := 0; i < 1000; i++ {
+		temps.Observe(30 + math.Floor(120*math.Sin(float64(i)*0.1))/10)
+	}
+
+	// Just for demonstration, let's check the state of the summary by
+	// (ab)using its Write method (which is usually only used by Prometheus
+	// internally).
+	metric := &dto.Metric{}
+	temps.Write(metric)
+	fmt.Println(proto.MarshalTextString(metric))
+
+	// Output:
+	// summary: <
+	//   sample_count: 1000
+	//   sample_sum: 29969.50000000001
+	//   quantile: <
+	//     quantile: 0.5
+	//     value: 31.1
+	//   >
+	//   quantile: <
+	//     quantile: 0.9
+	//     value: 41.3
+	//   >
+	//   quantile: <
+	//     quantile: 0.99
+	//     value: 41.9
+	//   >
+	// >
+}
+
+func ExampleSummaryVec() {
+	temps := prometheus.NewSummaryVec(
+		prometheus.SummaryOpts{
+			Name:       "pond_temperature_celsius",
+			Help:       "The temperature of the frog pond.",
+			Objectives: map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001},
+		},
+		[]string{"species"},
+	)
+
+	// Simulate some observations.
+	for i := 0; i < 1000; i++ {
+		temps.WithLabelValues("litoria-caerulea").Observe(30 + math.Floor(120*math.Sin(float64(i)*0.1))/10)
+		temps.WithLabelValues("lithobates-catesbeianus").Observe(32 + math.Floor(100*math.Cos(float64(i)*0.11))/10)
+	}
+
+	// Create a Summary without any observations.
+	temps.WithLabelValues("leiopelma-hochstetteri")
+
+	// Just for demonstration, let's check the state of the summary vector
+	// by registering it with a custom registry and then let it collect the
+	// metrics.
+	reg := prometheus.NewRegistry()
+	reg.MustRegister(temps)
+
+	metricFamilies, err := reg.Gather()
+	if err != nil || len(metricFamilies) != 1 {
+		panic("unexpected behavior of custom test registry")
+	}
+	fmt.Println(proto.MarshalTextString(metricFamilies[0]))
+
+	// Output:
+	// name: "pond_temperature_celsius"
+	// help: "The temperature of the frog pond."
+	// type: SUMMARY
+	// metric: <
+	//   label: <
+	//     name: "species"
+	//     value: "leiopelma-hochstetteri"
+	//   >
+	//   summary: <
+	//     sample_count: 0
+	//     sample_sum: 0
+	//     quantile: <
+	//       quantile: 0.5
+	//       value: nan
+	//     >
+	//     quantile: <
+	//       quantile: 0.9
+	//       value: nan
+	//     >
+	//     quantile: <
+	//       quantile: 0.99
+	//       value: nan
+	//     >
+	//   >
+	// >
+	// metric: <
+	//   label: <
+	//     name: "species"
+	//     value: "lithobates-catesbeianus"
+	//   >
+	//   summary: <
+	//     sample_count: 1000
+	//     sample_sum: 31956.100000000017
+	//     quantile: <
+	//       quantile: 0.5
+	//       value: 32.4
+	//     >
+	//     quantile: <
+	//       quantile: 0.9
+	//       value: 41.4
+	//     >
+	//     quantile: <
+	//       quantile: 0.99
+	//       value: 41.9
+	//     >
+	//   >
+	// >
+	// metric: <
+	//   label: <
+	//     name: "species"
+	//     value: "litoria-caerulea"
+	//   >
+	//   summary: <
+	//     sample_count: 1000
+	//     sample_sum: 29969.50000000001
+	//     quantile: <
+	//       quantile: 0.5
+	//       value: 31.1
+	//     >
+	//     quantile: <
+	//       quantile: 0.9
+	//       value: 41.3
+	//     >
+	//     quantile: <
+	//       quantile: 0.99
+	//       value: 41.9
+	//     >
+	//   >
+	// >
+}
+
+func ExampleNewConstSummary() {
+	desc := prometheus.NewDesc(
+		"http_request_duration_seconds",
+		"A summary of the HTTP request durations.",
+		[]string{"code", "method"},
+		prometheus.Labels{"owner": "example"},
+	)
+
+	// Create a constant summary from values we got from a 3rd party telemetry system.
+	s := prometheus.MustNewConstSummary(
+		desc,
+		4711, 403.34,
+		map[float64]float64{0.5: 42.3, 0.9: 323.3},
+		"200", "get",
+	)
+
+	// Just for demonstration, let's check the state of the summary by
+	// (ab)using its Write method (which is usually only used by Prometheus
+	// internally).
+	metric := &dto.Metric{}
+	s.Write(metric)
+	fmt.Println(proto.MarshalTextString(metric))
+
+	// Output:
+	// label: <
+	//   name: "code"
+	//   value: "200"
+	// >
+	// label: <
+	//   name: "method"
+	//   value: "get"
+	// >
+	// label: <
+	//   name: "owner"
+	//   value: "example"
+	// >
+	// summary: <
+	//   sample_count: 4711
+	//   sample_sum: 403.34
+	//   quantile: <
+	//     quantile: 0.5
+	//     value: 42.3
+	//   >
+	//   quantile: <
+	//     quantile: 0.9
+	//     value: 323.3
+	//   >
+	// >
+}
+
+func ExampleHistogram() {
+	temps := prometheus.NewHistogram(prometheus.HistogramOpts{
+		Name:    "pond_temperature_celsius",
+		Help:    "The temperature of the frog pond.", // Sorry, we can't measure how badly it smells.
+		Buckets: prometheus.LinearBuckets(20, 5, 5),  // 5 buckets, each 5 centigrade wide.
+	})
+
+	// Simulate some observations.
+	for i := 0; i < 1000; i++ {
+		temps.Observe(30 + math.Floor(120*math.Sin(float64(i)*0.1))/10)
+	}
+
+	// Just for demonstration, let's check the state of the histogram by
+	// (ab)using its Write method (which is usually only used by Prometheus
+	// internally).
+	metric := &dto.Metric{}
+	temps.Write(metric)
+	fmt.Println(proto.MarshalTextString(metric))
+
+	// Output:
+	// histogram: <
+	//   sample_count: 1000
+	//   sample_sum: 29969.50000000001
+	//   bucket: <
+	//     cumulative_count: 192
+	//     upper_bound: 20
+	//   >
+	//   bucket: <
+	//     cumulative_count: 366
+	//     upper_bound: 25
+	//   >
+	//   bucket: <
+	//     cumulative_count: 501
+	//     upper_bound: 30
+	//   >
+	//   bucket: <
+	//     cumulative_count: 638
+	//     upper_bound: 35
+	//   >
+	//   bucket: <
+	//     cumulative_count: 816
+	//     upper_bound: 40
+	//   >
+	// >
+}
+
+func ExampleNewConstHistogram() {
+	desc := prometheus.NewDesc(
+		"http_request_duration_seconds",
+		"A histogram of the HTTP request durations.",
+		[]string{"code", "method"},
+		prometheus.Labels{"owner": "example"},
+	)
+
+	// Create a constant histogram from values we got from a 3rd party telemetry system.
+	h := prometheus.MustNewConstHistogram(
+		desc,
+		4711, 403.34,
+		map[float64]uint64{25: 121, 50: 2403, 100: 3221, 200: 4233},
+		"200", "get",
+	)
+
+	// Just for demonstration, let's check the state of the histogram by
+	// (ab)using its Write method (which is usually only used by Prometheus
+	// internally).
+	metric := &dto.Metric{}
+	h.Write(metric)
+	fmt.Println(proto.MarshalTextString(metric))
+
+	// Output:
+	// label: <
+	//   name: "code"
+	//   value: "200"
+	// >
+	// label: <
+	//   name: "method"
+	//   value: "get"
+	// >
+	// label: <
+	//   name: "owner"
+	//   value: "example"
+	// >
+	// histogram: <
+	//   sample_count: 4711
+	//   sample_sum: 403.34
+	//   bucket: <
+	//     cumulative_count: 121
+	//     upper_bound: 25
+	//   >
+	//   bucket: <
+	//     cumulative_count: 2403
+	//     upper_bound: 50
+	//   >
+	//   bucket: <
+	//     cumulative_count: 3221
+	//     upper_bound: 100
+	//   >
+	//   bucket: <
+	//     cumulative_count: 4233
+	//     upper_bound: 200
+	//   >
+	// >
+}
+
+func ExampleAlreadyRegisteredError() {
+	reqCounter := prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "requests_total",
+		Help: "The total number of requests served.",
+	})
+	if err := prometheus.Register(reqCounter); err != nil {
+		if are, ok := err.(prometheus.AlreadyRegisteredError); ok {
+			// A counter for that metric has been registered before.
+			// Use the old counter from now on.
+			reqCounter = are.ExistingCollector.(prometheus.Counter)
+		} else {
+			// Something else went wrong!
+			panic(err)
+		}
+	}
+	reqCounter.Inc()
+}
+
+func ExampleGatherers() {
+	reg := prometheus.NewRegistry()
+	temp := prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Name: "temperature_kelvin",
+			Help: "Temperature in Kelvin.",
+		},
+		[]string{"location"},
+	)
+	reg.MustRegister(temp)
+	temp.WithLabelValues("outside").Set(273.14)
+	temp.WithLabelValues("inside").Set(298.44)
+
+	var parser expfmt.TextParser
+
+	text := `
+# TYPE humidity_percent gauge
+# HELP humidity_percent Humidity in %.
+humidity_percent{location="outside"} 45.4
+humidity_percent{location="inside"} 33.2
+# TYPE temperature_kelvin gauge
+# HELP temperature_kelvin Temperature in Kelvin.
+temperature_kelvin{location="somewhere else"} 4.5
+`
+
+	parseText := func() ([]*dto.MetricFamily, error) {
+		parsed, err := parser.TextToMetricFamilies(strings.NewReader(text))
+		if err != nil {
+			return nil, err
+		}
+		var result []*dto.MetricFamily
+		for _, mf := range parsed {
+			result = append(result, mf)
+		}
+		return result, nil
+	}
+
+	gatherers := prometheus.Gatherers{
+		reg,
+		prometheus.GathererFunc(parseText),
+	}
+
+	gathering, err := gatherers.Gather()
+	if err != nil {
+		fmt.Println(err)
+	}
+
+	out := &bytes.Buffer{}
+	for _, mf := range gathering {
+		if _, err := expfmt.MetricFamilyToText(out, mf); err != nil {
+			panic(err)
+		}
+	}
+	fmt.Print(out.String())
+	fmt.Println("----------")
+
+	// Note how the temperature_kelvin metric family has been merged from
+	// different sources. Now try
+	text = `
+# TYPE humidity_percent gauge
+# HELP humidity_percent Humidity in %.
+humidity_percent{location="outside"} 45.4
+humidity_percent{location="inside"} 33.2
+# TYPE temperature_kelvin gauge
+# HELP temperature_kelvin Temperature in Kelvin.
+# Duplicate metric:
+temperature_kelvin{location="outside"} 265.3
+ # Wrong labels:
+temperature_kelvin 4.5
+`
+
+	gathering, err = gatherers.Gather()
+	if err != nil {
+		fmt.Println(err)
+	}
+	// Note that still as many metrics as possible are returned:
+	out.Reset()
+	for _, mf := range gathering {
+		if _, err := expfmt.MetricFamilyToText(out, mf); err != nil {
+			panic(err)
+		}
+	}
+	fmt.Print(out.String())
+
+	// Output:
+	// # HELP humidity_percent Humidity in %.
+	// # TYPE humidity_percent gauge
+	// humidity_percent{location="inside"} 33.2
+	// humidity_percent{location="outside"} 45.4
+	// # HELP temperature_kelvin Temperature in Kelvin.
+	// # TYPE temperature_kelvin gauge
+	// temperature_kelvin{location="inside"} 298.44
+	// temperature_kelvin{location="outside"} 273.14
+	// temperature_kelvin{location="somewhere else"} 4.5
+	// ----------
+	// 2 error(s) occurred:
+	// * collected metric temperature_kelvin label:<name:"location" value:"outside" > gauge:<value:265.3 >  was collected before with the same name and label values
+	// * collected metric temperature_kelvin gauge:<value:4.5 >  has label dimensions inconsistent with previously collected metrics in the same metric family
+	// # HELP humidity_percent Humidity in %.
+	// # TYPE humidity_percent gauge
+	// humidity_percent{location="inside"} 33.2
+	// humidity_percent{location="outside"} 45.4
+	// # HELP temperature_kelvin Temperature in Kelvin.
+	// # TYPE temperature_kelvin gauge
+	// temperature_kelvin{location="inside"} 298.44
+	// temperature_kelvin{location="outside"} 273.14
+}

vendor/github.com/prometheus/client_golang/prometheus/expvar_collector.go

@@ -0,0 +1,119 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+import (
+	"encoding/json"
+	"expvar"
+)
+
+type expvarCollector struct {
+	exports map[string]*Desc
+}
+
+// NewExpvarCollector returns a newly allocated expvar Collector that still has
+// to be registered with a Prometheus registry.
+//
+// An expvar Collector collects metrics from the expvar interface. It provides a
+// quick way to expose numeric values that are already exported via expvar as
+// Prometheus metrics. Note that the data models of expvar and Prometheus are
+// fundamentally different, and that the expvar Collector is inherently slower
+// than native Prometheus metrics. Thus, the expvar Collector is probably great
+// for experiments and prototying, but you should seriously consider a more
+// direct implementation of Prometheus metrics for monitoring production
+// systems.
+//
+// The exports map has the following meaning:
+//
+// The keys in the map correspond to expvar keys, i.e. for every expvar key you
+// want to export as Prometheus metric, you need an entry in the exports
+// map. The descriptor mapped to each key describes how to export the expvar
+// value. It defines the name and the help string of the Prometheus metric
+// proxying the expvar value. The type will always be Untyped.
+//
+// For descriptors without variable labels, the expvar value must be a number or
+// a bool. The number is then directly exported as the Prometheus sample
+// value. (For a bool, 'false' translates to 0 and 'true' to 1). Expvar values
+// that are not numbers or bools are silently ignored.
+//
+// If the descriptor has one variable label, the expvar value must be an expvar
+// map. The keys in the expvar map become the various values of the one
+// Prometheus label. The values in the expvar map must be numbers or bools again
+// as above.
+//
+// For descriptors with more than one variable label, the expvar must be a
+// nested expvar map, i.e. where the values of the topmost map are maps again
+// etc. until a depth is reached that corresponds to the number of labels. The
+// leaves of that structure must be numbers or bools as above to serve as the
+// sample values.
+//
+// Anything that does not fit into the scheme above is silently ignored.
+func NewExpvarCollector(exports map[string]*Desc) Collector {
+	return &expvarCollector{
+		exports: exports,
+	}
+}
+
+// Describe implements Collector.
+func (e *expvarCollector) Describe(ch chan<- *Desc) {
+	for _, desc := range e.exports {
+		ch <- desc
+	}
+}
+
+// Collect implements Collector.
+func (e *expvarCollector) Collect(ch chan<- Metric) {
+	for name, desc := range e.exports {
+		var m Metric
+		expVar := expvar.Get(name)
+		if expVar == nil {
+			continue
+		}
+		var v interface{}
+		labels := make([]string, len(desc.variableLabels))
+		if err := json.Unmarshal([]byte(expVar.String()), &v); err != nil {
+			ch <- NewInvalidMetric(desc, err)
+			continue
+		}
+		var processValue func(v interface{}, i int)
+		processValue = func(v interface{}, i int) {
+			if i >= len(labels) {
+				copiedLabels := append(make([]string, 0, len(labels)), labels...)
+				switch v := v.(type) {
+				case float64:
+					m = MustNewConstMetric(desc, UntypedValue, v, copiedLabels...)
+				case bool:
+					if v {
+						m = MustNewConstMetric(desc, UntypedValue, 1, copiedLabels...)
+					} else {
+						m = MustNewConstMetric(desc, UntypedValue, 0, copiedLabels...)
+					}
+				default:
+					return
+				}
+				ch <- m
+				return
+			}
+			vm, ok := v.(map[string]interface{})
+			if !ok {
+				return
+			}
+			for lv, val := range vm {
+				labels[i] = lv
+				processValue(val, i+1)
+			}
+		}
+		processValue(v, 0)
+	}
+}

vendor/github.com/prometheus/client_golang/prometheus/expvar_collector_test.go

@@ -0,0 +1,97 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus_test
+
+import (
+	"expvar"
+	"fmt"
+	"sort"
+	"strings"
+
+	dto "github.com/prometheus/client_model/go"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+func ExampleNewExpvarCollector() {
+	expvarCollector := prometheus.NewExpvarCollector(map[string]*prometheus.Desc{
+		"memstats": prometheus.NewDesc(
+			"expvar_memstats",
+			"All numeric memstats as one metric family. Not a good role-model, actually... ;-)",
+			[]string{"type"}, nil,
+		),
+		"lone-int": prometheus.NewDesc(
+			"expvar_lone_int",
+			"Just an expvar int as an example.",
+			nil, nil,
+		),
+		"http-request-map": prometheus.NewDesc(
+			"expvar_http_request_total",
+			"How many http requests processed, partitioned by status code and http method.",
+			[]string{"code", "method"}, nil,
+		),
+	})
+	prometheus.MustRegister(expvarCollector)
+
+	// The Prometheus part is done here. But to show that this example is
+	// doing anything, we have to manually export something via expvar.  In
+	// real-life use-cases, some library would already have exported via
+	// expvar what we want to re-export as Prometheus metrics.
+	expvar.NewInt("lone-int").Set(42)
+	expvarMap := expvar.NewMap("http-request-map")
+	var (
+		expvarMap1, expvarMap2                             expvar.Map
+		expvarInt11, expvarInt12, expvarInt21, expvarInt22 expvar.Int
+	)
+	expvarMap1.Init()
+	expvarMap2.Init()
+	expvarInt11.Set(3)
+	expvarInt12.Set(13)
+	expvarInt21.Set(11)
+	expvarInt22.Set(212)
+	expvarMap1.Set("POST", &expvarInt11)
+	expvarMap1.Set("GET", &expvarInt12)
+	expvarMap2.Set("POST", &expvarInt21)
+	expvarMap2.Set("GET", &expvarInt22)
+	expvarMap.Set("404", &expvarMap1)
+	expvarMap.Set("200", &expvarMap2)
+	// Results in the following expvar map:
+	// "http-request-count": {"200": {"POST": 11, "GET": 212}, "404": {"POST": 3, "GET": 13}}
+
+	// Let's see what the scrape would yield, but exclude the memstats metrics.
+	metricStrings := []string{}
+	metric := dto.Metric{}
+	metricChan := make(chan prometheus.Metric)
+	go func() {
+		expvarCollector.Collect(metricChan)
+		close(metricChan)
+	}()
+	for m := range metricChan {
+		if strings.Index(m.Desc().String(), "expvar_memstats") == -1 {
+			metric.Reset()
+			m.Write(&metric)
+			metricStrings = append(metricStrings, metric.String())
+		}
+	}
+	sort.Strings(metricStrings)
+	for _, s := range metricStrings {
+		fmt.Println(strings.TrimRight(s, " "))
+	}
+	// Output:
+	// label:<name:"code" value:"200" > label:<name:"method" value:"GET" > untyped:<value:212 >
+	// label:<name:"code" value:"200" > label:<name:"method" value:"POST" > untyped:<value:11 >
+	// label:<name:"code" value:"404" > label:<name:"method" value:"GET" > untyped:<value:13 >
+	// label:<name:"code" value:"404" > label:<name:"method" value:"POST" > untyped:<value:3 >
+	// untyped:<value:42 >
+}

vendor/github.com/prometheus/client_golang/prometheus/fnv.go

@@ -0,0 +1,29 @@
+package prometheus
+
+// Inline and byte-free variant of hash/fnv's fnv64a.
+
+const (
+	offset64 = 14695981039346656037
+	prime64  = 1099511628211
+)
+
+// hashNew initializies a new fnv64a hash value.
+func hashNew() uint64 {
+	return offset64
+}
+
+// hashAdd adds a string to a fnv64a hash value, returning the updated hash.
+func hashAdd(h uint64, s string) uint64 {
+	for i := 0; i < len(s); i++ {
+		h ^= uint64(s[i])
+		h *= prime64
+	}
+	return h
+}
+
+// hashAddByte adds a byte to a fnv64a hash value, returning the updated hash.
+func hashAddByte(h uint64, b byte) uint64 {
+	h ^= uint64(b)
+	h *= prime64
+	return h
+}

vendor/github.com/prometheus/client_golang/prometheus/gauge.go

@@ -0,0 +1,173 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+// Gauge is a Metric that represents a single numerical value that can
+// arbitrarily go up and down.
+//
+// A Gauge is typically used for measured values like temperatures or current
+// memory usage, but also "counts" that can go up and down, like the number of
+// running goroutines.
+//
+// To create Gauge instances, use NewGauge.
+type Gauge interface {
+	Metric
+	Collector
+
+	// Set sets the Gauge to an arbitrary value.
+	Set(float64)
+	// Inc increments the Gauge by 1. Use Add to increment it by arbitrary
+	// values.
+	Inc()
+	// Dec decrements the Gauge by 1. Use Sub to decrement it by arbitrary
+	// values.
+	Dec()
+	// Add adds the given value to the Gauge. (The value can be negative,
+	// resulting in a decrease of the Gauge.)
+	Add(float64)
+	// Sub subtracts the given value from the Gauge. (The value can be
+	// negative, resulting in an increase of the Gauge.)
+	Sub(float64)
+
+	// SetToCurrentTime sets the Gauge to the current Unix time in seconds.
+	SetToCurrentTime()
+}
+
+// GaugeOpts is an alias for Opts. See there for doc comments.
+type GaugeOpts Opts
+
+// NewGauge creates a new Gauge based on the provided GaugeOpts.
+func NewGauge(opts GaugeOpts) Gauge {
+	return newValue(NewDesc(
+		BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
+		opts.Help,
+		nil,
+		opts.ConstLabels,
+	), GaugeValue, 0)
+}
+
+// GaugeVec is a Collector that bundles a set of Gauges that all share the same
+// Desc, but have different values for their variable labels. This is used if
+// you want to count the same thing partitioned by various dimensions
+// (e.g. number of operations queued, partitioned by user and operation
+// type). Create instances with NewGaugeVec.
+type GaugeVec struct {
+	*metricVec
+}
+
+// NewGaugeVec creates a new GaugeVec based on the provided GaugeOpts and
+// partitioned by the given label names.
+func NewGaugeVec(opts GaugeOpts, labelNames []string) *GaugeVec {
+	desc := NewDesc(
+		BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
+		opts.Help,
+		labelNames,
+		opts.ConstLabels,
+	)
+	return &GaugeVec{
+		metricVec: newMetricVec(desc, func(lvs ...string) Metric {
+			return newValue(desc, GaugeValue, 0, lvs...)
+		}),
+	}
+}
+
+// GetMetricWithLabelValues returns the Gauge for the given slice of label
+// values (same order as the VariableLabels in Desc). If that combination of
+// label values is accessed for the first time, a new Gauge is created.
+//
+// It is possible to call this method without using the returned Gauge to only
+// create the new Gauge but leave it at its starting value 0. See also the
+// SummaryVec example.
+//
+// Keeping the Gauge for later use is possible (and should be considered if
+// performance is critical), but keep in mind that Reset, DeleteLabelValues and
+// Delete can be used to delete the Gauge from the GaugeVec. In that case, the
+// Gauge will still exist, but it will not be exported anymore, even if a
+// Gauge with the same label values is created later. See also the CounterVec
+// example.
+//
+// An error is returned if the number of label values is not the same as the
+// number of VariableLabels in Desc.
+//
+// Note that for more than one label value, this method is prone to mistakes
+// caused by an incorrect order of arguments. Consider GetMetricWith(Labels) as
+// an alternative to avoid that type of mistake. For higher label numbers, the
+// latter has a much more readable (albeit more verbose) syntax, but it comes
+// with a performance overhead (for creating and processing the Labels map).
+func (m *GaugeVec) GetMetricWithLabelValues(lvs ...string) (Gauge, error) {
+	metric, err := m.metricVec.getMetricWithLabelValues(lvs...)
+	if metric != nil {
+		return metric.(Gauge), err
+	}
+	return nil, err
+}
+
+// GetMetricWith returns the Gauge for the given Labels map (the label names
+// must match those of the VariableLabels in Desc). If that label map is
+// accessed for the first time, a new Gauge is created. Implications of
+// creating a Gauge without using it and keeping the Gauge for later use are
+// the same as for GetMetricWithLabelValues.
+//
+// An error is returned if the number and names of the Labels are inconsistent
+// with those of the VariableLabels in Desc.
+//
+// This method is used for the same purpose as
+// GetMetricWithLabelValues(...string). See there for pros and cons of the two
+// methods.
+func (m *GaugeVec) GetMetricWith(labels Labels) (Gauge, error) {
+	metric, err := m.metricVec.getMetricWith(labels)
+	if metric != nil {
+		return metric.(Gauge), err
+	}
+	return nil, err
+}
+
+// WithLabelValues works as GetMetricWithLabelValues, but panics where
+// GetMetricWithLabelValues would have returned an error. By not returning an
+// error, WithLabelValues allows shortcuts like
+//     myVec.WithLabelValues("404", "GET").Add(42)
+func (m *GaugeVec) WithLabelValues(lvs ...string) Gauge {
+	return m.metricVec.withLabelValues(lvs...).(Gauge)
+}
+
+// With works as GetMetricWith, but panics where GetMetricWithLabels would have
+// returned an error. By not returning an error, With allows shortcuts like
+//     myVec.With(Labels{"code": "404", "method": "GET"}).Add(42)
+func (m *GaugeVec) With(labels Labels) Gauge {
+	return m.metricVec.with(labels).(Gauge)
+}
+
+// GaugeFunc is a Gauge whose value is determined at collect time by calling a
+// provided function.
+//
+// To create GaugeFunc instances, use NewGaugeFunc.
+type GaugeFunc interface {
+	Metric
+	Collector
+}
+
+// NewGaugeFunc creates a new GaugeFunc based on the provided GaugeOpts. The
+// value reported is determined by calling the given function from within the
+// Write method. Take into account that metric collection may happen
+// concurrently. If that results in concurrent calls to Write, like in the case
+// where a GaugeFunc is directly registered with Prometheus, the provided
+// function must be concurrency-safe.
+func NewGaugeFunc(opts GaugeOpts, function func() float64) GaugeFunc {
+	return newValueFunc(NewDesc(
+		BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
+		opts.Help,
+		nil,
+		opts.ConstLabels,
+	), GaugeValue, function)
+}

vendor/github.com/prometheus/client_golang/prometheus/gauge_test.go

@@ -0,0 +1,202 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+import (
+	"math"
+	"math/rand"
+	"sync"
+	"testing"
+	"testing/quick"
+	"time"
+
+	dto "github.com/prometheus/client_model/go"
+)
+
+func listenGaugeStream(vals, result chan float64, done chan struct{}) {
+	var sum float64
+outer:
+	for {
+		select {
+		case <-done:
+			close(vals)
+			for v := range vals {
+				sum += v
+			}
+			break outer
+		case v := <-vals:
+			sum += v
+		}
+	}
+	result <- sum
+	close(result)
+}
+
+func TestGaugeConcurrency(t *testing.T) {
+	it := func(n uint32) bool {
+		mutations := int(n % 10000)
+		concLevel := int(n%15 + 1)
+
+		var start, end sync.WaitGroup
+		start.Add(1)
+		end.Add(concLevel)
+
+		sStream := make(chan float64, mutations*concLevel)
+		result := make(chan float64)
+		done := make(chan struct{})
+
+		go listenGaugeStream(sStream, result, done)
+		go func() {
+			end.Wait()
+			close(done)
+		}()
+
+		gge := NewGauge(GaugeOpts{
+			Name: "test_gauge",
+			Help: "no help can be found here",
+		})
+		for i := 0; i < concLevel; i++ {
+			vals := make([]float64, mutations)
+			for j := 0; j < mutations; j++ {
+				vals[j] = rand.Float64() - 0.5
+			}
+
+			go func(vals []float64) {
+				start.Wait()
+				for _, v := range vals {
+					sStream <- v
+					gge.Add(v)
+				}
+				end.Done()
+			}(vals)
+		}
+		start.Done()
+
+		if expected, got := <-result, math.Float64frombits(gge.(*value).valBits); math.Abs(expected-got) > 0.000001 {
+			t.Fatalf("expected approx. %f, got %f", expected, got)
+			return false
+		}
+		return true
+	}
+
+	if err := quick.Check(it, nil); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestGaugeVecConcurrency(t *testing.T) {
+	it := func(n uint32) bool {
+		mutations := int(n % 10000)
+		concLevel := int(n%15 + 1)
+		vecLength := int(n%5 + 1)
+
+		var start, end sync.WaitGroup
+		start.Add(1)
+		end.Add(concLevel)
+
+		sStreams := make([]chan float64, vecLength)
+		results := make([]chan float64, vecLength)
+		done := make(chan struct{})
+
+		for i := 0; i < vecLength; i++ {
+			sStreams[i] = make(chan float64, mutations*concLevel)
+			results[i] = make(chan float64)
+			go listenGaugeStream(sStreams[i], results[i], done)
+		}
+
+		go func() {
+			end.Wait()
+			close(done)
+		}()
+
+		gge := NewGaugeVec(
+			GaugeOpts{
+				Name: "test_gauge",
+				Help: "no help can be found here",
+			},
+			[]string{"label"},
+		)
+		for i := 0; i < concLevel; i++ {
+			vals := make([]float64, mutations)
+			pick := make([]int, mutations)
+			for j := 0; j < mutations; j++ {
+				vals[j] = rand.Float64() - 0.5
+				pick[j] = rand.Intn(vecLength)
+			}
+
+			go func(vals []float64) {
+				start.Wait()
+				for i, v := range vals {
+					sStreams[pick[i]] <- v
+					gge.WithLabelValues(string('A' + pick[i])).Add(v)
+				}
+				end.Done()
+			}(vals)
+		}
+		start.Done()
+
+		for i := range sStreams {
+			if expected, got := <-results[i], math.Float64frombits(gge.WithLabelValues(string('A'+i)).(*value).valBits); math.Abs(expected-got) > 0.000001 {
+				t.Fatalf("expected approx. %f, got %f", expected, got)
+				return false
+			}
+		}
+		return true
+	}
+
+	if err := quick.Check(it, nil); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestGaugeFunc(t *testing.T) {
+	gf := NewGaugeFunc(
+		GaugeOpts{
+			Name:        "test_name",
+			Help:        "test help",
+			ConstLabels: Labels{"a": "1", "b": "2"},
+		},
+		func() float64 { return 3.1415 },
+	)
+
+	if expected, got := `Desc{fqName: "test_name", help: "test help", constLabels: {a="1",b="2"}, variableLabels: []}`, gf.Desc().String(); expected != got {
+		t.Errorf("expected %q, got %q", expected, got)
+	}
+
+	m := &dto.Metric{}
+	gf.Write(m)
+
+	if expected, got := `label:<name:"a" value:"1" > label:<name:"b" value:"2" > gauge:<value:3.1415 > `, m.String(); expected != got {
+		t.Errorf("expected %q, got %q", expected, got)
+	}
+}
+
+func TestGaugeSetCurrentTime(t *testing.T) {
+	g := NewGauge(GaugeOpts{
+		Name: "test_name",
+		Help: "test help",
+	})
+	g.SetToCurrentTime()
+	unixTime := float64(time.Now().Unix())
+
+	m := &dto.Metric{}
+	g.Write(m)
+
+	delta := unixTime - m.GetGauge().GetValue()
+	// This is just a smoke test to make sure SetToCurrentTime is not
+	// totally off. Tests with current time involved are hard...
+	if math.Abs(delta) > 5 {
+		t.Errorf("Gauge set to current time deviates from current time by more than 5s, delta is %f seconds", delta)
+	}
+}

vendor/github.com/prometheus/client_golang/prometheus/go_collector.go

@@ -0,0 +1,284 @@
+package prometheus
+
+import (
+	"fmt"
+	"runtime"
+	"runtime/debug"
+	"time"
+)
+
+type goCollector struct {
+	goroutinesDesc *Desc
+	threadsDesc    *Desc
+	gcDesc         *Desc
+	goInfoDesc     *Desc
+
+	// metrics to describe and collect
+	metrics memStatsMetrics
+}
+
+// NewGoCollector returns a collector which exports metrics about the current
+// go process.
+func NewGoCollector() Collector {
+	return &goCollector{
+		goroutinesDesc: NewDesc(
+			"go_goroutines",
+			"Number of goroutines that currently exist.",
+			nil, nil),
+		threadsDesc: NewDesc(
+			"go_threads",
+			"Number of OS threads created.",
+			nil, nil),
+		gcDesc: NewDesc(
+			"go_gc_duration_seconds",
+			"A summary of the GC invocation durations.",
+			nil, nil),
+		goInfoDesc: NewDesc(
+			"go_info",
+			"Information about the Go environment.",
+			nil, Labels{"version": runtime.Version()}),
+		metrics: memStatsMetrics{
+			{
+				desc: NewDesc(
+					memstatNamespace("alloc_bytes"),
+					"Number of bytes allocated and still in use.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.Alloc) },
+				valType: GaugeValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("alloc_bytes_total"),
+					"Total number of bytes allocated, even if freed.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.TotalAlloc) },
+				valType: CounterValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("sys_bytes"),
+					"Number of bytes obtained from system.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.Sys) },
+				valType: GaugeValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("lookups_total"),
+					"Total number of pointer lookups.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.Lookups) },
+				valType: CounterValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("mallocs_total"),
+					"Total number of mallocs.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.Mallocs) },
+				valType: CounterValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("frees_total"),
+					"Total number of frees.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.Frees) },
+				valType: CounterValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("heap_alloc_bytes"),
+					"Number of heap bytes allocated and still in use.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.HeapAlloc) },
+				valType: GaugeValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("heap_sys_bytes"),
+					"Number of heap bytes obtained from system.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.HeapSys) },
+				valType: GaugeValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("heap_idle_bytes"),
+					"Number of heap bytes waiting to be used.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.HeapIdle) },
+				valType: GaugeValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("heap_inuse_bytes"),
+					"Number of heap bytes that are in use.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.HeapInuse) },
+				valType: GaugeValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("heap_released_bytes"),
+					"Number of heap bytes released to OS.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.HeapReleased) },
+				valType: GaugeValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("heap_objects"),
+					"Number of allocated objects.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.HeapObjects) },
+				valType: GaugeValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("stack_inuse_bytes"),
+					"Number of bytes in use by the stack allocator.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.StackInuse) },
+				valType: GaugeValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("stack_sys_bytes"),
+					"Number of bytes obtained from system for stack allocator.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.StackSys) },
+				valType: GaugeValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("mspan_inuse_bytes"),
+					"Number of bytes in use by mspan structures.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.MSpanInuse) },
+				valType: GaugeValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("mspan_sys_bytes"),
+					"Number of bytes used for mspan structures obtained from system.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.MSpanSys) },
+				valType: GaugeValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("mcache_inuse_bytes"),
+					"Number of bytes in use by mcache structures.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.MCacheInuse) },
+				valType: GaugeValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("mcache_sys_bytes"),
+					"Number of bytes used for mcache structures obtained from system.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.MCacheSys) },
+				valType: GaugeValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("buck_hash_sys_bytes"),
+					"Number of bytes used by the profiling bucket hash table.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.BuckHashSys) },
+				valType: GaugeValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("gc_sys_bytes"),
+					"Number of bytes used for garbage collection system metadata.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.GCSys) },
+				valType: GaugeValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("other_sys_bytes"),
+					"Number of bytes used for other system allocations.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.OtherSys) },
+				valType: GaugeValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("next_gc_bytes"),
+					"Number of heap bytes when next garbage collection will take place.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.NextGC) },
+				valType: GaugeValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("last_gc_time_seconds"),
+					"Number of seconds since 1970 of last garbage collection.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return float64(ms.LastGC) / 1e9 },
+				valType: GaugeValue,
+			}, {
+				desc: NewDesc(
+					memstatNamespace("gc_cpu_fraction"),
+					"The fraction of this program's available CPU time used by the GC since the program started.",
+					nil, nil,
+				),
+				eval:    func(ms *runtime.MemStats) float64 { return ms.GCCPUFraction },
+				valType: GaugeValue,
+			},
+		},
+	}
+}
+
+func memstatNamespace(s string) string {
+	return fmt.Sprintf("go_memstats_%s", s)
+}
+
+// Describe returns all descriptions of the collector.
+func (c *goCollector) Describe(ch chan<- *Desc) {
+	ch <- c.goroutinesDesc
+	ch <- c.threadsDesc
+	ch <- c.gcDesc
+	ch <- c.goInfoDesc
+	for _, i := range c.metrics {
+		ch <- i.desc
+	}
+}
+
+// Collect returns the current state of all metrics of the collector.
+func (c *goCollector) Collect(ch chan<- Metric) {
+	ch <- MustNewConstMetric(c.goroutinesDesc, GaugeValue, float64(runtime.NumGoroutine()))
+	n, _ := runtime.ThreadCreateProfile(nil)
+	ch <- MustNewConstMetric(c.threadsDesc, GaugeValue, float64(n))
+
+	var stats debug.GCStats
+	stats.PauseQuantiles = make([]time.Duration, 5)
+	debug.ReadGCStats(&stats)
+
+	quantiles := make(map[float64]float64)
+	for idx, pq := range stats.PauseQuantiles[1:] {
+		quantiles[float64(idx+1)/float64(len(stats.PauseQuantiles)-1)] = pq.Seconds()
+	}
+	quantiles[0.0] = stats.PauseQuantiles[0].Seconds()
+	ch <- MustNewConstSummary(c.gcDesc, uint64(stats.NumGC), float64(stats.PauseTotal.Seconds()), quantiles)
+
+	ch <- MustNewConstMetric(c.goInfoDesc, GaugeValue, 1)
+
+	ms := &runtime.MemStats{}
+	runtime.ReadMemStats(ms)
+	for _, i := range c.metrics {
+		ch <- MustNewConstMetric(i.desc, i.valType, i.eval(ms))
+	}
+}
+
+// memStatsMetrics provide description, value, and value type for memstat metrics.
+type memStatsMetrics []struct {
+	desc    *Desc
+	eval    func(*runtime.MemStats) float64
+	valType ValueType
+}

vendor/github.com/prometheus/client_golang/prometheus/go_collector_test.go

@@ -0,0 +1,127 @@
+package prometheus
+
+import (
+	"runtime"
+	"testing"
+	"time"
+
+	dto "github.com/prometheus/client_model/go"
+)
+
+func TestGoCollector(t *testing.T) {
+	var (
+		c      = NewGoCollector()
+		ch     = make(chan Metric)
+		waitc  = make(chan struct{})
+		closec = make(chan struct{})
+		old    = -1
+	)
+	defer close(closec)
+
+	go func() {
+		c.Collect(ch)
+		go func(c <-chan struct{}) {
+			<-c
+		}(closec)
+		<-waitc
+		c.Collect(ch)
+	}()
+
+	for {
+		select {
+		case m := <-ch:
+			// m can be Gauge or Counter,
+			// currently just test the go_goroutines Gauge
+			// and ignore others.
+			if m.Desc().fqName != "go_goroutines" {
+				continue
+			}
+			pb := &dto.Metric{}
+			m.Write(pb)
+			if pb.GetGauge() == nil {
+				continue
+			}
+
+			if old == -1 {
+				old = int(pb.GetGauge().GetValue())
+				close(waitc)
+				continue
+			}
+
+			if diff := int(pb.GetGauge().GetValue()) - old; diff != 1 {
+				// TODO: This is flaky in highly concurrent situations.
+				t.Errorf("want 1 new goroutine, got %d", diff)
+			}
+
+			// GoCollector performs three sends per call.
+			// On line 27 we need to receive three more sends
+			// to shut down cleanly.
+			<-ch
+			<-ch
+			<-ch
+			return
+		case <-time.After(1 * time.Second):
+			t.Fatalf("expected collect timed out")
+		}
+	}
+}
+
+func TestGCCollector(t *testing.T) {
+	var (
+		c        = NewGoCollector()
+		ch       = make(chan Metric)
+		waitc    = make(chan struct{})
+		closec   = make(chan struct{})
+		oldGC    uint64
+		oldPause float64
+	)
+	defer close(closec)
+
+	go func() {
+		c.Collect(ch)
+		// force GC
+		runtime.GC()
+		<-waitc
+		c.Collect(ch)
+	}()
+
+	first := true
+	for {
+		select {
+		case metric := <-ch:
+			switch m := metric.(type) {
+			case *constSummary, *value:
+				pb := &dto.Metric{}
+				m.Write(pb)
+				if pb.GetSummary() == nil {
+					continue
+				}
+
+				if len(pb.GetSummary().Quantile) != 5 {
+					t.Errorf("expected 4 buckets, got %d", len(pb.GetSummary().Quantile))
+				}
+				for idx, want := range []float64{0.0, 0.25, 0.5, 0.75, 1.0} {
+					if *pb.GetSummary().Quantile[idx].Quantile != want {
+						t.Errorf("bucket #%d is off, got %f, want %f", idx, *pb.GetSummary().Quantile[idx].Quantile, want)
+					}
+				}
+				if first {
+					first = false
+					oldGC = *pb.GetSummary().SampleCount
+					oldPause = *pb.GetSummary().SampleSum
+					close(waitc)
+					continue
+				}
+				if diff := *pb.GetSummary().SampleCount - oldGC; diff != 1 {
+					t.Errorf("want 1 new garbage collection run, got %d", diff)
+				}
+				if diff := *pb.GetSummary().SampleSum - oldPause; diff <= 0 {
+					t.Errorf("want moar pause, got %f", diff)
+				}
+				return
+			}
+		case <-time.After(1 * time.Second):
+			t.Fatalf("expected collect timed out")
+		}
+	}
+}

vendor/github.com/prometheus/client_golang/prometheus/graphite/bridge.go

@@ -0,0 +1,280 @@
+// Copyright 2016 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package graphite provides a bridge to push Prometheus metrics to a Graphite
+// server.
+package graphite
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"sort"
+	"time"
+
+	"github.com/prometheus/common/expfmt"
+	"github.com/prometheus/common/model"
+	"golang.org/x/net/context"
+
+	dto "github.com/prometheus/client_model/go"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const (
+	defaultInterval       = 15 * time.Second
+	millisecondsPerSecond = 1000
+)
+
+// HandlerErrorHandling defines how a Handler serving metrics will handle
+// errors.
+type HandlerErrorHandling int
+
+// These constants cause handlers serving metrics to behave as described if
+// errors are encountered.
+const (
+	// Ignore errors and try to push as many metrics to Graphite as possible.
+	ContinueOnError HandlerErrorHandling = iota
+
+	// Abort the push to Graphite upon the first error encountered.
+	AbortOnError
+)
+
+// Config defines the Graphite bridge config.
+type Config struct {
+	// The url to push data to. Required.
+	URL string
+
+	// The prefix for the pushed Graphite metrics. Defaults to empty string.
+	Prefix string
+
+	// The interval to use for pushing data to Graphite. Defaults to 15 seconds.
+	Interval time.Duration
+
+	// The timeout for pushing metrics to Graphite. Defaults to 15 seconds.
+	Timeout time.Duration
+
+	// The Gatherer to use for metrics. Defaults to prometheus.DefaultGatherer.
+	Gatherer prometheus.Gatherer
+
+	// The logger that messages are written to. Defaults to no logging.
+	Logger Logger
+
+	// ErrorHandling defines how errors are handled. Note that errors are
+	// logged regardless of the configured ErrorHandling provided Logger
+	// is not nil.
+	ErrorHandling HandlerErrorHandling
+}
+
+// Bridge pushes metrics to the configured Graphite server.
+type Bridge struct {
+	url      string
+	prefix   string
+	interval time.Duration
+	timeout  time.Duration
+
+	errorHandling HandlerErrorHandling
+	logger        Logger
+
+	g prometheus.Gatherer
+}
+
+// Logger is the minimal interface Bridge needs for logging. Note that
+// log.Logger from the standard library implements this interface, and it is
+// easy to implement by custom loggers, if they don't do so already anyway.
+type Logger interface {
+	Println(v ...interface{})
+}
+
+// NewBridge returns a pointer to a new Bridge struct.
+func NewBridge(c *Config) (*Bridge, error) {
+	b := &Bridge{}
+
+	if c.URL == "" {
+		return nil, errors.New("missing URL")
+	}
+	b.url = c.URL
+
+	if c.Gatherer == nil {
+		b.g = prometheus.DefaultGatherer
+	} else {
+		b.g = c.Gatherer
+	}
+
+	if c.Logger != nil {
+		b.logger = c.Logger
+	}
+
+	if c.Prefix != "" {
+		b.prefix = c.Prefix
+	}
+
+	var z time.Duration
+	if c.Interval == z {
+		b.interval = defaultInterval
+	} else {
+		b.interval = c.Interval
+	}
+
+	if c.Timeout == z {
+		b.timeout = defaultInterval
+	} else {
+		b.timeout = c.Timeout
+	}
+
+	b.errorHandling = c.ErrorHandling
+
+	return b, nil
+}
+
+// Run starts the event loop that pushes Prometheus metrics to Graphite at the
+// configured interval.
+func (b *Bridge) Run(ctx context.Context) {
+	ticker := time.NewTicker(b.interval)
+	defer ticker.Stop()
+	for {
+		select {
+		case <-ticker.C:
+			if err := b.Push(); err != nil && b.logger != nil {
+				b.logger.Println("error pushing to Graphite:", err)
+			}
+		case <-ctx.Done():
+			return
+		}
+	}
+}
+
+// Push pushes Prometheus metrics to the configured Graphite server.
+func (b *Bridge) Push() error {
+	mfs, err := b.g.Gather()
+	if err != nil || len(mfs) == 0 {
+		switch b.errorHandling {
+		case AbortOnError:
+			return err
+		case ContinueOnError:
+			if b.logger != nil {
+				b.logger.Println("continue on error:", err)
+			}
+		default:
+			panic("unrecognized error handling value")
+		}
+	}
+
+	conn, err := net.DialTimeout("tcp", b.url, b.timeout)
+	if err != nil {
+		return err
+	}
+	defer conn.Close()
+
+	return writeMetrics(conn, mfs, b.prefix, model.Now())
+}
+
+func writeMetrics(w io.Writer, mfs []*dto.MetricFamily, prefix string, now model.Time) error {
+	vec, err := expfmt.ExtractSamples(&expfmt.DecodeOptions{
+		Timestamp: now,
+	}, mfs...)
+	if err != nil {
+		return err
+	}
+
+	buf := bufio.NewWriter(w)
+	for _, s := range vec {
+		if err := writeSanitized(buf, prefix); err != nil {
+			return err
+		}
+		if err := buf.WriteByte('.'); err != nil {
+			return err
+		}
+		if err := writeMetric(buf, s.Metric); err != nil {
+			return err
+		}
+		if _, err := fmt.Fprintf(buf, " %g %d\n", s.Value, int64(s.Timestamp)/millisecondsPerSecond); err != nil {
+			return err
+		}
+		if err := buf.Flush(); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func writeMetric(buf *bufio.Writer, m model.Metric) error {
+	metricName, hasName := m[model.MetricNameLabel]
+	numLabels := len(m) - 1
+	if !hasName {
+		numLabels = len(m)
+	}
+
+	labelStrings := make([]string, 0, numLabels)
+	for label, value := range m {
+		if label != model.MetricNameLabel {
+			labelStrings = append(labelStrings, fmt.Sprintf("%s %s", string(label), string(value)))
+		}
+	}
+
+	var err error
+	switch numLabels {
+	case 0:
+		if hasName {
+			return writeSanitized(buf, string(metricName))
+		}
+	default:
+		sort.Strings(labelStrings)
+		if err = writeSanitized(buf, string(metricName)); err != nil {
+			return err
+		}
+		for _, s := range labelStrings {
+			if err = buf.WriteByte('.'); err != nil {
+				return err
+			}
+			if err = writeSanitized(buf, s); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
+func writeSanitized(buf *bufio.Writer, s string) error {
+	prevUnderscore := false
+
+	for _, c := range s {
+		c = replaceInvalidRune(c)
+		if c == '_' {
+			if prevUnderscore {
+				continue
+			}
+			prevUnderscore = true
+		} else {
+			prevUnderscore = false
+		}
+		if _, err := buf.WriteRune(c); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func replaceInvalidRune(c rune) rune {
+	if c == ' ' {
+		return '.'
+	}
+	if !((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || c == '_' || c == ':' || (c >= '0' && c <= '9')) {
+		return '_'
+	}
+	return c
+}

vendor/github.com/prometheus/client_golang/prometheus/graphite/bridge_test.go

@@ -0,0 +1,309 @@
+package graphite
+
+import (
+	"bufio"
+	"bytes"
+	"io"
+	"log"
+	"net"
+	"os"
+	"regexp"
+	"testing"
+	"time"
+
+	"github.com/prometheus/common/model"
+	"golang.org/x/net/context"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+func TestSanitize(t *testing.T) {
+	testCases := []struct {
+		in, out string
+	}{
+		{in: "hello", out: "hello"},
+		{in: "hE/l1o", out: "hE_l1o"},
+		{in: "he,*ll(.o", out: "he_ll_o"},
+		{in: "hello_there%^&", out: "hello_there_"},
+	}
+
+	var buf bytes.Buffer
+	w := bufio.NewWriter(&buf)
+
+	for i, tc := range testCases {
+		if err := writeSanitized(w, tc.in); err != nil {
+			t.Fatalf("write failed: %v", err)
+		}
+		if err := w.Flush(); err != nil {
+			t.Fatalf("flush failed: %v", err)
+		}
+
+		if want, got := tc.out, buf.String(); want != got {
+			t.Fatalf("test case index %d: got sanitized string %s, want %s", i, got, want)
+		}
+
+		buf.Reset()
+	}
+}
+
+func TestWriteSummary(t *testing.T) {
+	sumVec := prometheus.NewSummaryVec(
+		prometheus.SummaryOpts{
+			Name:        "name",
+			Help:        "docstring",
+			ConstLabels: prometheus.Labels{"constname": "constvalue"},
+			Objectives:  map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001},
+		},
+		[]string{"labelname"},
+	)
+
+	sumVec.WithLabelValues("val1").Observe(float64(10))
+	sumVec.WithLabelValues("val1").Observe(float64(20))
+	sumVec.WithLabelValues("val1").Observe(float64(30))
+	sumVec.WithLabelValues("val2").Observe(float64(20))
+	sumVec.WithLabelValues("val2").Observe(float64(30))
+	sumVec.WithLabelValues("val2").Observe(float64(40))
+
+	reg := prometheus.NewRegistry()
+	reg.MustRegister(sumVec)
+
+	mfs, err := reg.Gather()
+	if err != nil {
+		t.Fatalf("error: %v", err)
+	}
+
+	now := model.Time(1477043083)
+	var buf bytes.Buffer
+	err = writeMetrics(&buf, mfs, "prefix", now)
+	if err != nil {
+		t.Fatalf("error: %v", err)
+	}
+
+	want := `prefix.name.constname.constvalue.labelname.val1.quantile.0_5 20 1477043
+prefix.name.constname.constvalue.labelname.val1.quantile.0_9 30 1477043
+prefix.name.constname.constvalue.labelname.val1.quantile.0_99 30 1477043
+prefix.name_sum.constname.constvalue.labelname.val1 60 1477043
+prefix.name_count.constname.constvalue.labelname.val1 3 1477043
+prefix.name.constname.constvalue.labelname.val2.quantile.0_5 30 1477043
+prefix.name.constname.constvalue.labelname.val2.quantile.0_9 40 1477043
+prefix.name.constname.constvalue.labelname.val2.quantile.0_99 40 1477043
+prefix.name_sum.constname.constvalue.labelname.val2 90 1477043
+prefix.name_count.constname.constvalue.labelname.val2 3 1477043
+`
+
+	if got := buf.String(); want != got {
+		t.Fatalf("wanted \n%s\n, got \n%s\n", want, got)
+	}
+}
+
+func TestWriteHistogram(t *testing.T) {
+	histVec := prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name:        "name",
+			Help:        "docstring",
+			ConstLabels: prometheus.Labels{"constname": "constvalue"},
+			Buckets:     []float64{0.01, 0.02, 0.05, 0.1},
+		},
+		[]string{"labelname"},
+	)
+
+	histVec.WithLabelValues("val1").Observe(float64(10))
+	histVec.WithLabelValues("val1").Observe(float64(20))
+	histVec.WithLabelValues("val1").Observe(float64(30))
+	histVec.WithLabelValues("val2").Observe(float64(20))
+	histVec.WithLabelValues("val2").Observe(float64(30))
+	histVec.WithLabelValues("val2").Observe(float64(40))
+
+	reg := prometheus.NewRegistry()
+	reg.MustRegister(histVec)
+
+	mfs, err := reg.Gather()
+	if err != nil {
+		t.Fatalf("error: %v", err)
+	}
+
+	now := model.Time(1477043083)
+	var buf bytes.Buffer
+	err = writeMetrics(&buf, mfs, "prefix", now)
+	if err != nil {
+		t.Fatalf("error: %v", err)
+	}
+
+	want := `prefix.name_bucket.constname.constvalue.labelname.val1.le.0_01 0 1477043
+prefix.name_bucket.constname.constvalue.labelname.val1.le.0_02 0 1477043
+prefix.name_bucket.constname.constvalue.labelname.val1.le.0_05 0 1477043
+prefix.name_bucket.constname.constvalue.labelname.val1.le.0_1 0 1477043
+prefix.name_sum.constname.constvalue.labelname.val1 60 1477043
+prefix.name_count.constname.constvalue.labelname.val1 3 1477043
+prefix.name_bucket.constname.constvalue.labelname.val1.le._Inf 3 1477043
+prefix.name_bucket.constname.constvalue.labelname.val2.le.0_01 0 1477043
+prefix.name_bucket.constname.constvalue.labelname.val2.le.0_02 0 1477043
+prefix.name_bucket.constname.constvalue.labelname.val2.le.0_05 0 1477043
+prefix.name_bucket.constname.constvalue.labelname.val2.le.0_1 0 1477043
+prefix.name_sum.constname.constvalue.labelname.val2 90 1477043
+prefix.name_count.constname.constvalue.labelname.val2 3 1477043
+prefix.name_bucket.constname.constvalue.labelname.val2.le._Inf 3 1477043
+`
+	if got := buf.String(); want != got {
+		t.Fatalf("wanted \n%s\n, got \n%s\n", want, got)
+	}
+}
+
+func TestToReader(t *testing.T) {
+	cntVec := prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name:        "name",
+			Help:        "docstring",
+			ConstLabels: prometheus.Labels{"constname": "constvalue"},
+		},
+		[]string{"labelname"},
+	)
+	cntVec.WithLabelValues("val1").Inc()
+	cntVec.WithLabelValues("val2").Inc()
+
+	reg := prometheus.NewRegistry()
+	reg.MustRegister(cntVec)
+
+	want := `prefix.name.constname.constvalue.labelname.val1 1 1477043
+prefix.name.constname.constvalue.labelname.val2 1 1477043
+`
+	mfs, err := reg.Gather()
+	if err != nil {
+		t.Fatalf("error: %v", err)
+	}
+
+	now := model.Time(1477043083)
+	var buf bytes.Buffer
+	err = writeMetrics(&buf, mfs, "prefix", now)
+	if err != nil {
+		t.Fatalf("error: %v", err)
+	}
+
+	if got := buf.String(); want != got {
+		t.Fatalf("wanted \n%s\n, got \n%s\n", want, got)
+	}
+}
+
+func TestPush(t *testing.T) {
+	reg := prometheus.NewRegistry()
+	cntVec := prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name:        "name",
+			Help:        "docstring",
+			ConstLabels: prometheus.Labels{"constname": "constvalue"},
+		},
+		[]string{"labelname"},
+	)
+	cntVec.WithLabelValues("val1").Inc()
+	cntVec.WithLabelValues("val2").Inc()
+	reg.MustRegister(cntVec)
+
+	host := "localhost"
+	port := ":56789"
+	b, err := NewBridge(&Config{
+		URL:      host + port,
+		Gatherer: reg,
+		Prefix:   "prefix",
+	})
+	if err != nil {
+		t.Fatalf("error creating bridge: %v", err)
+	}
+
+	nmg, err := newMockGraphite(port)
+	if err != nil {
+		t.Fatalf("error creating mock graphite: %v", err)
+	}
+	defer nmg.Close()
+
+	err = b.Push()
+	if err != nil {
+		t.Fatalf("error pushing: %v", err)
+	}
+
+	wants := []string{
+		"prefix.name.constname.constvalue.labelname.val1 1",
+		"prefix.name.constname.constvalue.labelname.val2 1",
+	}
+
+	select {
+	case got := <-nmg.readc:
+		for _, want := range wants {
+			matched, err := regexp.MatchString(want, got)
+			if err != nil {
+				t.Fatalf("error pushing: %v", err)
+			}
+			if !matched {
+				t.Fatalf("missing metric:\nno match for %s received by server:\n%s", want, got)
+			}
+		}
+		return
+	case err := <-nmg.errc:
+		t.Fatalf("error reading push: %v", err)
+	case <-time.After(50 * time.Millisecond):
+		t.Fatalf("no result from graphite server")
+	}
+}
+
+func newMockGraphite(port string) (*mockGraphite, error) {
+	readc := make(chan string)
+	errc := make(chan error)
+	ln, err := net.Listen("tcp", port)
+	if err != nil {
+		return nil, err
+	}
+
+	go func() {
+		conn, err := ln.Accept()
+		if err != nil {
+			errc <- err
+		}
+		var b bytes.Buffer
+		io.Copy(&b, conn)
+		readc <- b.String()
+	}()
+
+	return &mockGraphite{
+		readc:    readc,
+		errc:     errc,
+		Listener: ln,
+	}, nil
+}
+
+type mockGraphite struct {
+	readc chan string
+	errc  chan error
+
+	net.Listener
+}
+
+func ExampleBridge() {
+	b, err := NewBridge(&Config{
+		URL:           "graphite.example.org:3099",
+		Gatherer:      prometheus.DefaultGatherer,
+		Prefix:        "prefix",
+		Interval:      15 * time.Second,
+		Timeout:       10 * time.Second,
+		ErrorHandling: AbortOnError,
+		Logger:        log.New(os.Stdout, "graphite bridge: ", log.Lshortfile),
+	})
+	if err != nil {
+		panic(err)
+	}
+
+	go func() {
+		// Start something in a goroutine that uses metrics.
+	}()
+
+	// Push initial metrics to Graphite. Fail fast if the push fails.
+	if err := b.Push(); err != nil {
+		panic(err)
+	}
+
+	// Create a Context to control stopping the Run() loop that pushes
+	// metrics to Graphite.
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	// Start pushing metrics to Graphite in the Run() loop.
+	b.Run(ctx)
+}

vendor/github.com/prometheus/client_golang/prometheus/histogram.go

@@ -0,0 +1,473 @@
+// Copyright 2015 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+import (
+	"fmt"
+	"math"
+	"sort"
+	"sync/atomic"
+
+	"github.com/golang/protobuf/proto"
+
+	dto "github.com/prometheus/client_model/go"
+)
+
+// A Histogram counts individual observations from an event or sample stream in
+// configurable buckets. Similar to a summary, it also provides a sum of
+// observations and an observation count.
+//
+// On the Prometheus server, quantiles can be calculated from a Histogram using
+// the histogram_quantile function in the query language.
+//
+// Note that Histograms, in contrast to Summaries, can be aggregated with the
+// Prometheus query language (see the documentation for detailed
+// procedures). However, Histograms require the user to pre-define suitable
+// buckets, and they are in general less accurate. The Observe method of a
+// Histogram has a very low performance overhead in comparison with the Observe
+// method of a Summary.
+//
+// To create Histogram instances, use NewHistogram.
+type Histogram interface {
+	Metric
+	Collector
+
+	// Observe adds a single observation to the histogram.
+	Observe(float64)
+}
+
+// bucketLabel is used for the label that defines the upper bound of a
+// bucket of a histogram ("le" -> "less or equal").
+const bucketLabel = "le"
+
+// DefBuckets are the default Histogram buckets. The default buckets are
+// tailored to broadly measure the response time (in seconds) of a network
+// service. Most likely, however, you will be required to define buckets
+// customized to your use case.
+var (
+	DefBuckets = []float64{.005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5, 10}
+
+	errBucketLabelNotAllowed = fmt.Errorf(
+		"%q is not allowed as label name in histograms", bucketLabel,
+	)
+)
+
+// LinearBuckets creates 'count' buckets, each 'width' wide, where the lowest
+// bucket has an upper bound of 'start'. The final +Inf bucket is not counted
+// and not included in the returned slice. The returned slice is meant to be
+// used for the Buckets field of HistogramOpts.
+//
+// The function panics if 'count' is zero or negative.
+func LinearBuckets(start, width float64, count int) []float64 {
+	if count < 1 {
+		panic("LinearBuckets needs a positive count")
+	}
+	buckets := make([]float64, count)
+	for i := range buckets {
+		buckets[i] = start
+		start += width
+	}
+	return buckets
+}
+
+// ExponentialBuckets creates 'count' buckets, where the lowest bucket has an
+// upper bound of 'start' and each following bucket's upper bound is 'factor'
+// times the previous bucket's upper bound. The final +Inf bucket is not counted
+// and not included in the returned slice. The returned slice is meant to be
+// used for the Buckets field of HistogramOpts.
+//
+// The function panics if 'count' is 0 or negative, if 'start' is 0 or negative,
+// or if 'factor' is less than or equal 1.
+func ExponentialBuckets(start, factor float64, count int) []float64 {
+	if count < 1 {
+		panic("ExponentialBuckets needs a positive count")
+	}
+	if start <= 0 {
+		panic("ExponentialBuckets needs a positive start value")
+	}
+	if factor <= 1 {
+		panic("ExponentialBuckets needs a factor greater than 1")
+	}
+	buckets := make([]float64, count)
+	for i := range buckets {
+		buckets[i] = start
+		start *= factor
+	}
+	return buckets
+}
+
+// HistogramOpts bundles the options for creating a Histogram metric. It is
+// mandatory to set Name and Help to a non-empty string. All other fields are
+// optional and can safely be left at their zero value.
+type HistogramOpts struct {
+	// Namespace, Subsystem, and Name are components of the fully-qualified
+	// name of the Histogram (created by joining these components with
+	// "_"). Only Name is mandatory, the others merely help structuring the
+	// name. Note that the fully-qualified name of the Histogram must be a
+	// valid Prometheus metric name.
+	Namespace string
+	Subsystem string
+	Name      string
+
+	// Help provides information about this Histogram. Mandatory!
+	//
+	// Metrics with the same fully-qualified name must have the same Help
+	// string.
+	Help string
+
+	// ConstLabels are used to attach fixed labels to this
+	// Histogram. Histograms with the same fully-qualified name must have the
+	// same label names in their ConstLabels.
+	//
+	// Note that in most cases, labels have a value that varies during the
+	// lifetime of a process. Those labels are usually managed with a
+	// HistogramVec. ConstLabels serve only special purposes. One is for the
+	// special case where the value of a label does not change during the
+	// lifetime of a process, e.g. if the revision of the running binary is
+	// put into a label. Another, more advanced purpose is if more than one
+	// Collector needs to collect Histograms with the same fully-qualified
+	// name. In that case, those Summaries must differ in the values of
+	// their ConstLabels. See the Collector examples.
+	//
+	// If the value of a label never changes (not even between binaries),
+	// that label most likely should not be a label at all (but part of the
+	// metric name).
+	ConstLabels Labels
+
+	// Buckets defines the buckets into which observations are counted. Each
+	// element in the slice is the upper inclusive bound of a bucket. The
+	// values must be sorted in strictly increasing order. There is no need
+	// to add a highest bucket with +Inf bound, it will be added
+	// implicitly. The default value is DefBuckets.
+	Buckets []float64
+}
+
+// NewHistogram creates a new Histogram based on the provided HistogramOpts. It
+// panics if the buckets in HistogramOpts are not in strictly increasing order.
+func NewHistogram(opts HistogramOpts) Histogram {
+	return newHistogram(
+		NewDesc(
+			BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
+			opts.Help,
+			nil,
+			opts.ConstLabels,
+		),
+		opts,
+	)
+}
+
+func newHistogram(desc *Desc, opts HistogramOpts, labelValues ...string) Histogram {
+	if len(desc.variableLabels) != len(labelValues) {
+		panic(errInconsistentCardinality)
+	}
+
+	for _, n := range desc.variableLabels {
+		if n == bucketLabel {
+			panic(errBucketLabelNotAllowed)
+		}
+	}
+	for _, lp := range desc.constLabelPairs {
+		if lp.GetName() == bucketLabel {
+			panic(errBucketLabelNotAllowed)
+		}
+	}
+
+	if len(opts.Buckets) == 0 {
+		opts.Buckets = DefBuckets
+	}
+
+	h := &histogram{
+		desc:        desc,
+		upperBounds: opts.Buckets,
+		labelPairs:  makeLabelPairs(desc, labelValues),
+	}
+	for i, upperBound := range h.upperBounds {
+		if i < len(h.upperBounds)-1 {
+			if upperBound >= h.upperBounds[i+1] {
+				panic(fmt.Errorf(
+					"histogram buckets must be in increasing order: %f >= %f",
+					upperBound, h.upperBounds[i+1],
+				))
+			}
+		} else {
+			if math.IsInf(upperBound, +1) {
+				// The +Inf bucket is implicit. Remove it here.
+				h.upperBounds = h.upperBounds[:i]
+			}
+		}
+	}
+	// Finally we know the final length of h.upperBounds and can make counts.
+	h.counts = make([]uint64, len(h.upperBounds))
+
+	h.init(h) // Init self-collection.
+	return h
+}
+
+type histogram struct {
+	// sumBits contains the bits of the float64 representing the sum of all
+	// observations. sumBits and count have to go first in the struct to
+	// guarantee alignment for atomic operations.
+	// http://golang.org/pkg/sync/atomic/#pkg-note-BUG
+	sumBits uint64
+	count   uint64
+
+	selfCollector
+	// Note that there is no mutex required.
+
+	desc *Desc
+
+	upperBounds []float64
+	counts      []uint64
+
+	labelPairs []*dto.LabelPair
+}
+
+func (h *histogram) Desc() *Desc {
+	return h.desc
+}
+
+func (h *histogram) Observe(v float64) {
+	// TODO(beorn7): For small numbers of buckets (<30), a linear search is
+	// slightly faster than the binary search. If we really care, we could
+	// switch from one search strategy to the other depending on the number
+	// of buckets.
+	//
+	// Microbenchmarks (BenchmarkHistogramNoLabels):
+	// 11 buckets: 38.3 ns/op linear - binary 48.7 ns/op
+	// 100 buckets: 78.1 ns/op linear - binary 54.9 ns/op
+	// 300 buckets: 154 ns/op linear - binary 61.6 ns/op
+	i := sort.SearchFloat64s(h.upperBounds, v)
+	if i < len(h.counts) {
+		atomic.AddUint64(&h.counts[i], 1)
+	}
+	atomic.AddUint64(&h.count, 1)
+	for {
+		oldBits := atomic.LoadUint64(&h.sumBits)
+		newBits := math.Float64bits(math.Float64frombits(oldBits) + v)
+		if atomic.CompareAndSwapUint64(&h.sumBits, oldBits, newBits) {
+			break
+		}
+	}
+}
+
+func (h *histogram) Write(out *dto.Metric) error {
+	his := &dto.Histogram{}
+	buckets := make([]*dto.Bucket, len(h.upperBounds))
+
+	his.SampleSum = proto.Float64(math.Float64frombits(atomic.LoadUint64(&h.sumBits)))
+	his.SampleCount = proto.Uint64(atomic.LoadUint64(&h.count))
+	var count uint64
+	for i, upperBound := range h.upperBounds {
+		count += atomic.LoadUint64(&h.counts[i])
+		buckets[i] = &dto.Bucket{
+			CumulativeCount: proto.Uint64(count),
+			UpperBound:      proto.Float64(upperBound),
+		}
+	}
+	his.Bucket = buckets
+	out.Histogram = his
+	out.Label = h.labelPairs
+	return nil
+}
+
+// HistogramVec is a Collector that bundles a set of Histograms that all share the
+// same Desc, but have different values for their variable labels. This is used
+// if you want to count the same thing partitioned by various dimensions
+// (e.g. HTTP request latencies, partitioned by status code and method). Create
+// instances with NewHistogramVec.
+type HistogramVec struct {
+	*metricVec
+}
+
+// NewHistogramVec creates a new HistogramVec based on the provided HistogramOpts and
+// partitioned by the given label names.
+func NewHistogramVec(opts HistogramOpts, labelNames []string) *HistogramVec {
+	desc := NewDesc(
+		BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
+		opts.Help,
+		labelNames,
+		opts.ConstLabels,
+	)
+	return &HistogramVec{
+		metricVec: newMetricVec(desc, func(lvs ...string) Metric {
+			return newHistogram(desc, opts, lvs...)
+		}),
+	}
+}
+
+// GetMetricWithLabelValues returns the Histogram for the given slice of label
+// values (same order as the VariableLabels in Desc). If that combination of
+// label values is accessed for the first time, a new Histogram is created.
+//
+// It is possible to call this method without using the returned Histogram to only
+// create the new Histogram but leave it at its starting value, a Histogram without
+// any observations.
+//
+// Keeping the Histogram for later use is possible (and should be considered if
+// performance is critical), but keep in mind that Reset, DeleteLabelValues and
+// Delete can be used to delete the Histogram from the HistogramVec. In that case, the
+// Histogram will still exist, but it will not be exported anymore, even if a
+// Histogram with the same label values is created later. See also the CounterVec
+// example.
+//
+// An error is returned if the number of label values is not the same as the
+// number of VariableLabels in Desc.
+//
+// Note that for more than one label value, this method is prone to mistakes
+// caused by an incorrect order of arguments. Consider GetMetricWith(Labels) as
+// an alternative to avoid that type of mistake. For higher label numbers, the
+// latter has a much more readable (albeit more verbose) syntax, but it comes
+// with a performance overhead (for creating and processing the Labels map).
+// See also the GaugeVec example.
+func (m *HistogramVec) GetMetricWithLabelValues(lvs ...string) (Observer, error) {
+	metric, err := m.metricVec.getMetricWithLabelValues(lvs...)
+	if metric != nil {
+		return metric.(Observer), err
+	}
+	return nil, err
+}
+
+// GetMetricWith returns the Histogram for the given Labels map (the label names
+// must match those of the VariableLabels in Desc). If that label map is
+// accessed for the first time, a new Histogram is created. Implications of
+// creating a Histogram without using it and keeping the Histogram for later use
+// are the same as for GetMetricWithLabelValues.
+//
+// An error is returned if the number and names of the Labels are inconsistent
+// with those of the VariableLabels in Desc.
+//
+// This method is used for the same purpose as
+// GetMetricWithLabelValues(...string). See there for pros and cons of the two
+// methods.
+func (m *HistogramVec) GetMetricWith(labels Labels) (Observer, error) {
+	metric, err := m.metricVec.getMetricWith(labels)
+	if metric != nil {
+		return metric.(Observer), err
+	}
+	return nil, err
+}
+
+// WithLabelValues works as GetMetricWithLabelValues, but panics where
+// GetMetricWithLabelValues would have returned an error. By not returning an
+// error, WithLabelValues allows shortcuts like
+//     myVec.WithLabelValues("404", "GET").Observe(42.21)
+func (m *HistogramVec) WithLabelValues(lvs ...string) Observer {
+	return m.metricVec.withLabelValues(lvs...).(Observer)
+}
+
+// With works as GetMetricWith, but panics where GetMetricWithLabels would have
+// returned an error. By not returning an error, With allows shortcuts like
+//     myVec.With(Labels{"code": "404", "method": "GET"}).Observe(42.21)
+func (m *HistogramVec) With(labels Labels) Observer {
+	return m.metricVec.with(labels).(Observer)
+}
+
+type constHistogram struct {
+	desc       *Desc
+	count      uint64
+	sum        float64
+	buckets    map[float64]uint64
+	labelPairs []*dto.LabelPair
+}
+
+func (h *constHistogram) Desc() *Desc {
+	return h.desc
+}
+
+func (h *constHistogram) Write(out *dto.Metric) error {
+	his := &dto.Histogram{}
+	buckets := make([]*dto.Bucket, 0, len(h.buckets))
+
+	his.SampleCount = proto.Uint64(h.count)
+	his.SampleSum = proto.Float64(h.sum)
+
+	for upperBound, count := range h.buckets {
+		buckets = append(buckets, &dto.Bucket{
+			CumulativeCount: proto.Uint64(count),
+			UpperBound:      proto.Float64(upperBound),
+		})
+	}
+
+	if len(buckets) > 0 {
+		sort.Sort(buckSort(buckets))
+	}
+	his.Bucket = buckets
+
+	out.Histogram = his
+	out.Label = h.labelPairs
+
+	return nil
+}
+
+// NewConstHistogram returns a metric representing a Prometheus histogram with
+// fixed values for the count, sum, and bucket counts. As those parameters
+// cannot be changed, the returned value does not implement the Histogram
+// interface (but only the Metric interface). Users of this package will not
+// have much use for it in regular operations. However, when implementing custom
+// Collectors, it is useful as a throw-away metric that is generated on the fly
+// to send it to Prometheus in the Collect method.
+//
+// buckets is a map of upper bounds to cumulative counts, excluding the +Inf
+// bucket.
+//
+// NewConstHistogram returns an error if the length of labelValues is not
+// consistent with the variable labels in Desc.
+func NewConstHistogram(
+	desc *Desc,
+	count uint64,
+	sum float64,
+	buckets map[float64]uint64,
+	labelValues ...string,
+) (Metric, error) {
+	if err := validateLabelValues(labelValues, len(desc.variableLabels)); err != nil {
+		return nil, err
+	}
+	return &constHistogram{
+		desc:       desc,
+		count:      count,
+		sum:        sum,
+		buckets:    buckets,
+		labelPairs: makeLabelPairs(desc, labelValues),
+	}, nil
+}
+
+// MustNewConstHistogram is a version of NewConstHistogram that panics where
+// NewConstMetric would have returned an error.
+func MustNewConstHistogram(
+	desc *Desc,
+	count uint64,
+	sum float64,
+	buckets map[float64]uint64,
+	labelValues ...string,
+) Metric {
+	m, err := NewConstHistogram(desc, count, sum, buckets, labelValues...)
+	if err != nil {
+		panic(err)
+	}
+	return m
+}
+
+type buckSort []*dto.Bucket
+
+func (s buckSort) Len() int {
+	return len(s)
+}
+
+func (s buckSort) Swap(i, j int) {
+	s[i], s[j] = s[j], s[i]
+}
+
+func (s buckSort) Less(i, j int) bool {
+	return s[i].GetUpperBound() < s[j].GetUpperBound()
+}

vendor/github.com/prometheus/client_golang/prometheus/histogram_test.go

@@ -0,0 +1,348 @@
+// Copyright 2015 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+import (
+	"math"
+	"math/rand"
+	"reflect"
+	"sort"
+	"sync"
+	"testing"
+	"testing/quick"
+
+	dto "github.com/prometheus/client_model/go"
+)
+
+func benchmarkHistogramObserve(w int, b *testing.B) {
+	b.StopTimer()
+
+	wg := new(sync.WaitGroup)
+	wg.Add(w)
+
+	g := new(sync.WaitGroup)
+	g.Add(1)
+
+	s := NewHistogram(HistogramOpts{})
+
+	for i := 0; i < w; i++ {
+		go func() {
+			g.Wait()
+
+			for i := 0; i < b.N; i++ {
+				s.Observe(float64(i))
+			}
+
+			wg.Done()
+		}()
+	}
+
+	b.StartTimer()
+	g.Done()
+	wg.Wait()
+}
+
+func BenchmarkHistogramObserve1(b *testing.B) {
+	benchmarkHistogramObserve(1, b)
+}
+
+func BenchmarkHistogramObserve2(b *testing.B) {
+	benchmarkHistogramObserve(2, b)
+}
+
+func BenchmarkHistogramObserve4(b *testing.B) {
+	benchmarkHistogramObserve(4, b)
+}
+
+func BenchmarkHistogramObserve8(b *testing.B) {
+	benchmarkHistogramObserve(8, b)
+}
+
+func benchmarkHistogramWrite(w int, b *testing.B) {
+	b.StopTimer()
+
+	wg := new(sync.WaitGroup)
+	wg.Add(w)
+
+	g := new(sync.WaitGroup)
+	g.Add(1)
+
+	s := NewHistogram(HistogramOpts{})
+
+	for i := 0; i < 1000000; i++ {
+		s.Observe(float64(i))
+	}
+
+	for j := 0; j < w; j++ {
+		outs := make([]dto.Metric, b.N)
+
+		go func(o []dto.Metric) {
+			g.Wait()
+
+			for i := 0; i < b.N; i++ {
+				s.Write(&o[i])
+			}
+
+			wg.Done()
+		}(outs)
+	}
+
+	b.StartTimer()
+	g.Done()
+	wg.Wait()
+}
+
+func BenchmarkHistogramWrite1(b *testing.B) {
+	benchmarkHistogramWrite(1, b)
+}
+
+func BenchmarkHistogramWrite2(b *testing.B) {
+	benchmarkHistogramWrite(2, b)
+}
+
+func BenchmarkHistogramWrite4(b *testing.B) {
+	benchmarkHistogramWrite(4, b)
+}
+
+func BenchmarkHistogramWrite8(b *testing.B) {
+	benchmarkHistogramWrite(8, b)
+}
+
+func TestHistogramNonMonotonicBuckets(t *testing.T) {
+	testCases := map[string][]float64{
+		"not strictly monotonic":  {1, 2, 2, 3},
+		"not monotonic at all":    {1, 2, 4, 3, 5},
+		"have +Inf in the middle": {1, 2, math.Inf(+1), 3},
+	}
+	for name, buckets := range testCases {
+		func() {
+			defer func() {
+				if r := recover(); r == nil {
+					t.Errorf("Buckets %v are %s but NewHistogram did not panic.", buckets, name)
+				}
+			}()
+			_ = NewHistogram(HistogramOpts{
+				Name:    "test_histogram",
+				Help:    "helpless",
+				Buckets: buckets,
+			})
+		}()
+	}
+}
+
+// Intentionally adding +Inf here to test if that case is handled correctly.
+// Also, getCumulativeCounts depends on it.
+var testBuckets = []float64{-2, -1, -0.5, 0, 0.5, 1, 2, math.Inf(+1)}
+
+func TestHistogramConcurrency(t *testing.T) {
+	if testing.Short() {
+		t.Skip("Skipping test in short mode.")
+	}
+
+	rand.Seed(42)
+
+	it := func(n uint32) bool {
+		mutations := int(n%1e4 + 1e4)
+		concLevel := int(n%5 + 1)
+		total := mutations * concLevel
+
+		var start, end sync.WaitGroup
+		start.Add(1)
+		end.Add(concLevel)
+
+		sum := NewHistogram(HistogramOpts{
+			Name:    "test_histogram",
+			Help:    "helpless",
+			Buckets: testBuckets,
+		})
+
+		allVars := make([]float64, total)
+		var sampleSum float64
+		for i := 0; i < concLevel; i++ {
+			vals := make([]float64, mutations)
+			for j := 0; j < mutations; j++ {
+				v := rand.NormFloat64()
+				vals[j] = v
+				allVars[i*mutations+j] = v
+				sampleSum += v
+			}
+
+			go func(vals []float64) {
+				start.Wait()
+				for _, v := range vals {
+					sum.Observe(v)
+				}
+				end.Done()
+			}(vals)
+		}
+		sort.Float64s(allVars)
+		start.Done()
+		end.Wait()
+
+		m := &dto.Metric{}
+		sum.Write(m)
+		if got, want := int(*m.Histogram.SampleCount), total; got != want {
+			t.Errorf("got sample count %d, want %d", got, want)
+		}
+		if got, want := *m.Histogram.SampleSum, sampleSum; math.Abs((got-want)/want) > 0.001 {
+			t.Errorf("got sample sum %f, want %f", got, want)
+		}
+
+		wantCounts := getCumulativeCounts(allVars)
+
+		if got, want := len(m.Histogram.Bucket), len(testBuckets)-1; got != want {
+			t.Errorf("got %d buckets in protobuf, want %d", got, want)
+		}
+		for i, wantBound := range testBuckets {
+			if i == len(testBuckets)-1 {
+				break // No +Inf bucket in protobuf.
+			}
+			if gotBound := *m.Histogram.Bucket[i].UpperBound; gotBound != wantBound {
+				t.Errorf("got bound %f, want %f", gotBound, wantBound)
+			}
+			if gotCount, wantCount := *m.Histogram.Bucket[i].CumulativeCount, wantCounts[i]; gotCount != wantCount {
+				t.Errorf("got count %d, want %d", gotCount, wantCount)
+			}
+		}
+		return true
+	}
+
+	if err := quick.Check(it, nil); err != nil {
+		t.Error(err)
+	}
+}
+
+func TestHistogramVecConcurrency(t *testing.T) {
+	if testing.Short() {
+		t.Skip("Skipping test in short mode.")
+	}
+
+	rand.Seed(42)
+
+	objectives := make([]float64, 0, len(DefObjectives))
+	for qu := range DefObjectives {
+
+		objectives = append(objectives, qu)
+	}
+	sort.Float64s(objectives)
+
+	it := func(n uint32) bool {
+		mutations := int(n%1e4 + 1e4)
+		concLevel := int(n%7 + 1)
+		vecLength := int(n%3 + 1)
+
+		var start, end sync.WaitGroup
+		start.Add(1)
+		end.Add(concLevel)
+
+		his := NewHistogramVec(
+			HistogramOpts{
+				Name:    "test_histogram",
+				Help:    "helpless",
+				Buckets: []float64{-2, -1, -0.5, 0, 0.5, 1, 2, math.Inf(+1)},
+			},
+			[]string{"label"},
+		)
+
+		allVars := make([][]float64, vecLength)
+		sampleSums := make([]float64, vecLength)
+		for i := 0; i < concLevel; i++ {
+			vals := make([]float64, mutations)
+			picks := make([]int, mutations)
+			for j := 0; j < mutations; j++ {
+				v := rand.NormFloat64()
+				vals[j] = v
+				pick := rand.Intn(vecLength)
+				picks[j] = pick
+				allVars[pick] = append(allVars[pick], v)
+				sampleSums[pick] += v
+			}
+
+			go func(vals []float64) {
+				start.Wait()
+				for i, v := range vals {
+					his.WithLabelValues(string('A' + picks[i])).Observe(v)
+				}
+				end.Done()
+			}(vals)
+		}
+		for _, vars := range allVars {
+			sort.Float64s(vars)
+		}
+		start.Done()
+		end.Wait()
+
+		for i := 0; i < vecLength; i++ {
+			m := &dto.Metric{}
+			s := his.WithLabelValues(string('A' + i))
+			s.(Histogram).Write(m)
+
+			if got, want := len(m.Histogram.Bucket), len(testBuckets)-1; got != want {
+				t.Errorf("got %d buckets in protobuf, want %d", got, want)
+			}
+			if got, want := int(*m.Histogram.SampleCount), len(allVars[i]); got != want {
+				t.Errorf("got sample count %d, want %d", got, want)
+			}
+			if got, want := *m.Histogram.SampleSum, sampleSums[i]; math.Abs((got-want)/want) > 0.001 {
+				t.Errorf("got sample sum %f, want %f", got, want)
+			}
+
+			wantCounts := getCumulativeCounts(allVars[i])
+
+			for j, wantBound := range testBuckets {
+				if j == len(testBuckets)-1 {
+					break // No +Inf bucket in protobuf.
+				}
+				if gotBound := *m.Histogram.Bucket[j].UpperBound; gotBound != wantBound {
+					t.Errorf("got bound %f, want %f", gotBound, wantBound)
+				}
+				if gotCount, wantCount := *m.Histogram.Bucket[j].CumulativeCount, wantCounts[j]; gotCount != wantCount {
+					t.Errorf("got count %d, want %d", gotCount, wantCount)
+				}
+			}
+		}
+		return true
+	}
+
+	if err := quick.Check(it, nil); err != nil {
+		t.Error(err)
+	}
+}
+
+func getCumulativeCounts(vars []float64) []uint64 {
+	counts := make([]uint64, len(testBuckets))
+	for _, v := range vars {
+		for i := len(testBuckets) - 1; i >= 0; i-- {
+			if v > testBuckets[i] {
+				break
+			}
+			counts[i]++
+		}
+	}
+	return counts
+}
+
+func TestBuckets(t *testing.T) {
+	got := LinearBuckets(-15, 5, 6)
+	want := []float64{-15, -10, -5, 0, 5, 10}
+	if !reflect.DeepEqual(got, want) {
+		t.Errorf("linear buckets: got %v, want %v", got, want)
+	}
+
+	got = ExponentialBuckets(100, 1.2, 3)
+	want = []float64{100, 120, 144}
+	if !reflect.DeepEqual(got, want) {
+		t.Errorf("linear buckets: got %v, want %v", got, want)
+	}
+}

vendor/github.com/prometheus/client_golang/prometheus/http.go

@@ -0,0 +1,524 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+import (
+	"bufio"
+	"bytes"
+	"compress/gzip"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/prometheus/common/expfmt"
+)
+
+// TODO(beorn7): Remove this whole file. It is a partial mirror of
+// promhttp/http.go (to avoid circular import chains) where everything HTTP
+// related should live. The functions here are just for avoiding
+// breakage. Everything is deprecated.
+
+const (
+	contentTypeHeader     = "Content-Type"
+	contentLengthHeader   = "Content-Length"
+	contentEncodingHeader = "Content-Encoding"
+	acceptEncodingHeader  = "Accept-Encoding"
+)
+
+var bufPool sync.Pool
+
+func getBuf() *bytes.Buffer {
+	buf := bufPool.Get()
+	if buf == nil {
+		return &bytes.Buffer{}
+	}
+	return buf.(*bytes.Buffer)
+}
+
+func giveBuf(buf *bytes.Buffer) {
+	buf.Reset()
+	bufPool.Put(buf)
+}
+
+// Handler returns an HTTP handler for the DefaultGatherer. It is
+// already instrumented with InstrumentHandler (using "prometheus" as handler
+// name).
+//
+// Deprecated: Please note the issues described in the doc comment of
+// InstrumentHandler. You might want to consider using promhttp.Handler instead
+// (which is not instrumented, but can be instrumented with the tooling provided
+// in package promhttp).
+func Handler() http.Handler {
+	return InstrumentHandler("prometheus", UninstrumentedHandler())
+}
+
+// UninstrumentedHandler returns an HTTP handler for the DefaultGatherer.
+//
+// Deprecated: Use promhttp.Handler instead. See there for further documentation.
+func UninstrumentedHandler() http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+		mfs, err := DefaultGatherer.Gather()
+		if err != nil {
+			http.Error(w, "An error has occurred during metrics collection:\n\n"+err.Error(), http.StatusInternalServerError)
+			return
+		}
+
+		contentType := expfmt.Negotiate(req.Header)
+		buf := getBuf()
+		defer giveBuf(buf)
+		writer, encoding := decorateWriter(req, buf)
+		enc := expfmt.NewEncoder(writer, contentType)
+		var lastErr error
+		for _, mf := range mfs {
+			if err := enc.Encode(mf); err != nil {
+				lastErr = err
+				http.Error(w, "An error has occurred during metrics encoding:\n\n"+err.Error(), http.StatusInternalServerError)
+				return
+			}
+		}
+		if closer, ok := writer.(io.Closer); ok {
+			closer.Close()
+		}
+		if lastErr != nil && buf.Len() == 0 {
+			http.Error(w, "No metrics encoded, last error:\n\n"+lastErr.Error(), http.StatusInternalServerError)
+			return
+		}
+		header := w.Header()
+		header.Set(contentTypeHeader, string(contentType))
+		header.Set(contentLengthHeader, fmt.Sprint(buf.Len()))
+		if encoding != "" {
+			header.Set(contentEncodingHeader, encoding)
+		}
+		w.Write(buf.Bytes())
+	})
+}
+
+// decorateWriter wraps a writer to handle gzip compression if requested.  It
+// returns the decorated writer and the appropriate "Content-Encoding" header
+// (which is empty if no compression is enabled).
+func decorateWriter(request *http.Request, writer io.Writer) (io.Writer, string) {
+	header := request.Header.Get(acceptEncodingHeader)
+	parts := strings.Split(header, ",")
+	for _, part := range parts {
+		part := strings.TrimSpace(part)
+		if part == "gzip" || strings.HasPrefix(part, "gzip;") {
+			return gzip.NewWriter(writer), "gzip"
+		}
+	}
+	return writer, ""
+}
+
+var instLabels = []string{"method", "code"}
+
+type nower interface {
+	Now() time.Time
+}
+
+type nowFunc func() time.Time
+
+func (n nowFunc) Now() time.Time {
+	return n()
+}
+
+var now nower = nowFunc(func() time.Time {
+	return time.Now()
+})
+
+func nowSeries(t ...time.Time) nower {
+	return nowFunc(func() time.Time {
+		defer func() {
+			t = t[1:]
+		}()
+
+		return t[0]
+	})
+}
+
+// InstrumentHandler wraps the given HTTP handler for instrumentation. It
+// registers four metric collectors (if not already done) and reports HTTP
+// metrics to the (newly or already) registered collectors: http_requests_total
+// (CounterVec), http_request_duration_microseconds (Summary),
+// http_request_size_bytes (Summary), http_response_size_bytes (Summary). Each
+// has a constant label named "handler" with the provided handlerName as
+// value. http_requests_total is a metric vector partitioned by HTTP method
+// (label name "method") and HTTP status code (label name "code").
+//
+// Deprecated: InstrumentHandler has several issues. Use the tooling provided in
+// package promhttp instead. The issues are the following:
+//
+// - It uses Summaries rather than Histograms. Summaries are not useful if
+// aggregation across multiple instances is required.
+//
+// - It uses microseconds as unit, which is deprecated and should be replaced by
+// seconds.
+//
+// - The size of the request is calculated in a separate goroutine. Since this
+// calculator requires access to the request header, it creates a race with
+// any writes to the header performed during request handling.
+// httputil.ReverseProxy is a prominent example for a handler
+// performing such writes.
+//
+// - It has additional issues with HTTP/2, cf.
+// https://github.com/prometheus/client_golang/issues/272.
+func InstrumentHandler(handlerName string, handler http.Handler) http.HandlerFunc {
+	return InstrumentHandlerFunc(handlerName, handler.ServeHTTP)
+}
+
+// InstrumentHandlerFunc wraps the given function for instrumentation. It
+// otherwise works in the same way as InstrumentHandler (and shares the same
+// issues).
+//
+// Deprecated: InstrumentHandlerFunc is deprecated for the same reasons as
+// InstrumentHandler is. Use the tooling provided in package promhttp instead.
+func InstrumentHandlerFunc(handlerName string, handlerFunc func(http.ResponseWriter, *http.Request)) http.HandlerFunc {
+	return InstrumentHandlerFuncWithOpts(
+		SummaryOpts{
+			Subsystem:   "http",
+			ConstLabels: Labels{"handler": handlerName},
+			Objectives:  map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001},
+		},
+		handlerFunc,
+	)
+}
+
+// InstrumentHandlerWithOpts works like InstrumentHandler (and shares the same
+// issues) but provides more flexibility (at the cost of a more complex call
+// syntax). As InstrumentHandler, this function registers four metric
+// collectors, but it uses the provided SummaryOpts to create them. However, the
+// fields "Name" and "Help" in the SummaryOpts are ignored. "Name" is replaced
+// by "requests_total", "request_duration_microseconds", "request_size_bytes",
+// and "response_size_bytes", respectively. "Help" is replaced by an appropriate
+// help string. The names of the variable labels of the http_requests_total
+// CounterVec are "method" (get, post, etc.), and "code" (HTTP status code).
+//
+// If InstrumentHandlerWithOpts is called as follows, it mimics exactly the
+// behavior of InstrumentHandler:
+//
+//     prometheus.InstrumentHandlerWithOpts(
+//         prometheus.SummaryOpts{
+//              Subsystem:   "http",
+//              ConstLabels: prometheus.Labels{"handler": handlerName},
+//         },
+//         handler,
+//     )
+//
+// Technical detail: "requests_total" is a CounterVec, not a SummaryVec, so it
+// cannot use SummaryOpts. Instead, a CounterOpts struct is created internally,
+// and all its fields are set to the equally named fields in the provided
+// SummaryOpts.
+//
+// Deprecated: InstrumentHandlerWithOpts is deprecated for the same reasons as
+// InstrumentHandler is. Use the tooling provided in package promhttp instead.
+func InstrumentHandlerWithOpts(opts SummaryOpts, handler http.Handler) http.HandlerFunc {
+	return InstrumentHandlerFuncWithOpts(opts, handler.ServeHTTP)
+}
+
+// InstrumentHandlerFuncWithOpts works like InstrumentHandlerFunc (and shares
+// the same issues) but provides more flexibility (at the cost of a more complex
+// call syntax). See InstrumentHandlerWithOpts for details how the provided
+// SummaryOpts are used.
+//
+// Deprecated: InstrumentHandlerFuncWithOpts is deprecated for the same reasons
+// as InstrumentHandler is. Use the tooling provided in package promhttp instead.
+func InstrumentHandlerFuncWithOpts(opts SummaryOpts, handlerFunc func(http.ResponseWriter, *http.Request)) http.HandlerFunc {
+	reqCnt := NewCounterVec(
+		CounterOpts{
+			Namespace:   opts.Namespace,
+			Subsystem:   opts.Subsystem,
+			Name:        "requests_total",
+			Help:        "Total number of HTTP requests made.",
+			ConstLabels: opts.ConstLabels,
+		},
+		instLabels,
+	)
+	if err := Register(reqCnt); err != nil {
+		if are, ok := err.(AlreadyRegisteredError); ok {
+			reqCnt = are.ExistingCollector.(*CounterVec)
+		} else {
+			panic(err)
+		}
+	}
+
+	opts.Name = "request_duration_microseconds"
+	opts.Help = "The HTTP request latencies in microseconds."
+	reqDur := NewSummary(opts)
+	if err := Register(reqDur); err != nil {
+		if are, ok := err.(AlreadyRegisteredError); ok {
+			reqDur = are.ExistingCollector.(Summary)
+		} else {
+			panic(err)
+		}
+	}
+
+	opts.Name = "request_size_bytes"
+	opts.Help = "The HTTP request sizes in bytes."
+	reqSz := NewSummary(opts)
+	if err := Register(reqSz); err != nil {
+		if are, ok := err.(AlreadyRegisteredError); ok {
+			reqSz = are.ExistingCollector.(Summary)
+		} else {
+			panic(err)
+		}
+	}
+
+	opts.Name = "response_size_bytes"
+	opts.Help = "The HTTP response sizes in bytes."
+	resSz := NewSummary(opts)
+	if err := Register(resSz); err != nil {
+		if are, ok := err.(AlreadyRegisteredError); ok {
+			resSz = are.ExistingCollector.(Summary)
+		} else {
+			panic(err)
+		}
+	}
+
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		now := time.Now()
+
+		delegate := &responseWriterDelegator{ResponseWriter: w}
+		out := computeApproximateRequestSize(r)
+
+		_, cn := w.(http.CloseNotifier)
+		_, fl := w.(http.Flusher)
+		_, hj := w.(http.Hijacker)
+		_, rf := w.(io.ReaderFrom)
+		var rw http.ResponseWriter
+		if cn && fl && hj && rf {
+			rw = &fancyResponseWriterDelegator{delegate}
+		} else {
+			rw = delegate
+		}
+		handlerFunc(rw, r)
+
+		elapsed := float64(time.Since(now)) / float64(time.Microsecond)
+
+		method := sanitizeMethod(r.Method)
+		code := sanitizeCode(delegate.status)
+		reqCnt.WithLabelValues(method, code).Inc()
+		reqDur.Observe(elapsed)
+		resSz.Observe(float64(delegate.written))
+		reqSz.Observe(float64(<-out))
+	})
+}
+
+func computeApproximateRequestSize(r *http.Request) <-chan int {
+	// Get URL length in current go routine for avoiding a race condition.
+	// HandlerFunc that runs in parallel may modify the URL.
+	s := 0
+	if r.URL != nil {
+		s += len(r.URL.String())
+	}
+
+	out := make(chan int, 1)
+
+	go func() {
+		s += len(r.Method)
+		s += len(r.Proto)
+		for name, values := range r.Header {
+			s += len(name)
+			for _, value := range values {
+				s += len(value)
+			}
+		}
+		s += len(r.Host)
+
+		// N.B. r.Form and r.MultipartForm are assumed to be included in r.URL.
+
+		if r.ContentLength != -1 {
+			s += int(r.ContentLength)
+		}
+		out <- s
+		close(out)
+	}()
+
+	return out
+}
+
+type responseWriterDelegator struct {
+	http.ResponseWriter
+
+	handler, method string
+	status          int
+	written         int64
+	wroteHeader     bool
+}
+
+func (r *responseWriterDelegator) WriteHeader(code int) {
+	r.status = code
+	r.wroteHeader = true
+	r.ResponseWriter.WriteHeader(code)
+}
+
+func (r *responseWriterDelegator) Write(b []byte) (int, error) {
+	if !r.wroteHeader {
+		r.WriteHeader(http.StatusOK)
+	}
+	n, err := r.ResponseWriter.Write(b)
+	r.written += int64(n)
+	return n, err
+}
+
+type fancyResponseWriterDelegator struct {
+	*responseWriterDelegator
+}
+
+func (f *fancyResponseWriterDelegator) CloseNotify() <-chan bool {
+	return f.ResponseWriter.(http.CloseNotifier).CloseNotify()
+}
+
+func (f *fancyResponseWriterDelegator) Flush() {
+	f.ResponseWriter.(http.Flusher).Flush()
+}
+
+func (f *fancyResponseWriterDelegator) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	return f.ResponseWriter.(http.Hijacker).Hijack()
+}
+
+func (f *fancyResponseWriterDelegator) ReadFrom(r io.Reader) (int64, error) {
+	if !f.wroteHeader {
+		f.WriteHeader(http.StatusOK)
+	}
+	n, err := f.ResponseWriter.(io.ReaderFrom).ReadFrom(r)
+	f.written += n
+	return n, err
+}
+
+func sanitizeMethod(m string) string {
+	switch m {
+	case "GET", "get":
+		return "get"
+	case "PUT", "put":
+		return "put"
+	case "HEAD", "head":
+		return "head"
+	case "POST", "post":
+		return "post"
+	case "DELETE", "delete":
+		return "delete"
+	case "CONNECT", "connect":
+		return "connect"
+	case "OPTIONS", "options":
+		return "options"
+	case "NOTIFY", "notify":
+		return "notify"
+	default:
+		return strings.ToLower(m)
+	}
+}
+
+func sanitizeCode(s int) string {
+	switch s {
+	case 100:
+		return "100"
+	case 101:
+		return "101"
+
+	case 200:
+		return "200"
+	case 201:
+		return "201"
+	case 202:
+		return "202"
+	case 203:
+		return "203"
+	case 204:
+		return "204"
+	case 205:
+		return "205"
+	case 206:
+		return "206"
+
+	case 300:
+		return "300"
+	case 301:
+		return "301"
+	case 302:
+		return "302"
+	case 304:
+		return "304"
+	case 305:
+		return "305"
+	case 307:
+		return "307"
+
+	case 400:
+		return "400"
+	case 401:
+		return "401"
+	case 402:
+		return "402"
+	case 403:
+		return "403"
+	case 404:
+		return "404"
+	case 405:
+		return "405"
+	case 406:
+		return "406"
+	case 407:
+		return "407"
+	case 408:
+		return "408"
+	case 409:
+		return "409"
+	case 410:
+		return "410"
+	case 411:
+		return "411"
+	case 412:
+		return "412"
+	case 413:
+		return "413"
+	case 414:
+		return "414"
+	case 415:
+		return "415"
+	case 416:
+		return "416"
+	case 417:
+		return "417"
+	case 418:
+		return "418"
+
+	case 500:
+		return "500"
+	case 501:
+		return "501"
+	case 502:
+		return "502"
+	case 503:
+		return "503"
+	case 504:
+		return "504"
+	case 505:
+		return "505"
+
+	case 428:
+		return "428"
+	case 429:
+		return "429"
+	case 431:
+		return "431"
+	case 511:
+		return "511"
+
+	default:
+		return strconv.Itoa(s)
+	}
+}

vendor/github.com/prometheus/client_golang/prometheus/http_test.go

@@ -0,0 +1,154 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	dto "github.com/prometheus/client_model/go"
+)
+
+type respBody string
+
+func (b respBody) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	w.WriteHeader(http.StatusTeapot)
+	w.Write([]byte(b))
+}
+
+func TestInstrumentHandler(t *testing.T) {
+	defer func(n nower) {
+		now = n.(nower)
+	}(now)
+
+	instant := time.Now()
+	end := instant.Add(30 * time.Second)
+	now = nowSeries(instant, end)
+	respBody := respBody("Howdy there!")
+
+	hndlr := InstrumentHandler("test-handler", respBody)
+
+	opts := SummaryOpts{
+		Subsystem:   "http",
+		ConstLabels: Labels{"handler": "test-handler"},
+		Objectives:  map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001},
+	}
+
+	reqCnt := NewCounterVec(
+		CounterOpts{
+			Namespace:   opts.Namespace,
+			Subsystem:   opts.Subsystem,
+			Name:        "requests_total",
+			Help:        "Total number of HTTP requests made.",
+			ConstLabels: opts.ConstLabels,
+		},
+		instLabels,
+	)
+	err := Register(reqCnt)
+	if err == nil {
+		t.Fatal("expected reqCnt to be registered already")
+	}
+	if are, ok := err.(AlreadyRegisteredError); ok {
+		reqCnt = are.ExistingCollector.(*CounterVec)
+	} else {
+		t.Fatal("unexpected registration error:", err)
+	}
+
+	opts.Name = "request_duration_microseconds"
+	opts.Help = "The HTTP request latencies in microseconds."
+	reqDur := NewSummary(opts)
+	err = Register(reqDur)
+	if err == nil {
+		t.Fatal("expected reqDur to be registered already")
+	}
+	if are, ok := err.(AlreadyRegisteredError); ok {
+		reqDur = are.ExistingCollector.(Summary)
+	} else {
+		t.Fatal("unexpected registration error:", err)
+	}
+
+	opts.Name = "request_size_bytes"
+	opts.Help = "The HTTP request sizes in bytes."
+	reqSz := NewSummary(opts)
+	err = Register(reqSz)
+	if err == nil {
+		t.Fatal("expected reqSz to be registered already")
+	}
+	if _, ok := err.(AlreadyRegisteredError); !ok {
+		t.Fatal("unexpected registration error:", err)
+	}
+
+	opts.Name = "response_size_bytes"
+	opts.Help = "The HTTP response sizes in bytes."
+	resSz := NewSummary(opts)
+	err = Register(resSz)
+	if err == nil {
+		t.Fatal("expected resSz to be registered already")
+	}
+	if _, ok := err.(AlreadyRegisteredError); !ok {
+		t.Fatal("unexpected registration error:", err)
+	}
+
+	reqCnt.Reset()
+
+	resp := httptest.NewRecorder()
+	req := &http.Request{
+		Method: "GET",
+	}
+
+	hndlr.ServeHTTP(resp, req)
+
+	if resp.Code != http.StatusTeapot {
+		t.Fatalf("expected status %d, got %d", http.StatusTeapot, resp.Code)
+	}
+	if string(resp.Body.Bytes()) != "Howdy there!" {
+		t.Fatalf("expected body %s, got %s", "Howdy there!", string(resp.Body.Bytes()))
+	}
+
+	out := &dto.Metric{}
+	reqDur.Write(out)
+	if want, got := "test-handler", out.Label[0].GetValue(); want != got {
+		t.Errorf("want label value %q in reqDur, got %q", want, got)
+	}
+	if want, got := uint64(1), out.Summary.GetSampleCount(); want != got {
+		t.Errorf("want sample count %d in reqDur, got %d", want, got)
+	}
+
+	out.Reset()
+	if want, got := 1, len(reqCnt.children); want != got {
+		t.Errorf("want %d children in reqCnt, got %d", want, got)
+	}
+	cnt, err := reqCnt.GetMetricWithLabelValues("get", "418")
+	if err != nil {
+		t.Fatal(err)
+	}
+	cnt.Write(out)
+	if want, got := "418", out.Label[0].GetValue(); want != got {
+		t.Errorf("want label value %q in reqCnt, got %q", want, got)
+	}
+	if want, got := "test-handler", out.Label[1].GetValue(); want != got {
+		t.Errorf("want label value %q in reqCnt, got %q", want, got)
+	}
+	if want, got := "get", out.Label[2].GetValue(); want != got {
+		t.Errorf("want label value %q in reqCnt, got %q", want, got)
+	}
+	if out.Counter == nil {
+		t.Fatal("expected non-nil counter in reqCnt")
+	}
+	if want, got := 1., out.Counter.GetValue(); want != got {
+		t.Errorf("want reqCnt of %f, got %f", want, got)
+	}
+}

vendor/github.com/prometheus/client_golang/prometheus/labels.go

@@ -0,0 +1,57 @@
+package prometheus
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+	"unicode/utf8"
+
+	"github.com/prometheus/common/model"
+)
+
+// Labels represents a collection of label name -> value mappings. This type is
+// commonly used with the With(Labels) and GetMetricWith(Labels) methods of
+// metric vector Collectors, e.g.:
+//     myVec.With(Labels{"code": "404", "method": "GET"}).Add(42)
+//
+// The other use-case is the specification of constant label pairs in Opts or to
+// create a Desc.
+type Labels map[string]string
+
+// reservedLabelPrefix is a prefix which is not legal in user-supplied
+// label names.
+const reservedLabelPrefix = "__"
+
+var errInconsistentCardinality = errors.New("inconsistent label cardinality")
+
+func validateValuesInLabels(labels Labels, expectedNumberOfValues int) error {
+	if len(labels) != expectedNumberOfValues {
+		return errInconsistentCardinality
+	}
+
+	for name, val := range labels {
+		if !utf8.ValidString(val) {
+			return fmt.Errorf("label %s: value %q is not valid UTF-8", name, val)
+		}
+	}
+
+	return nil
+}
+
+func validateLabelValues(vals []string, expectedNumberOfValues int) error {
+	if len(vals) != expectedNumberOfValues {
+		return errInconsistentCardinality
+	}
+
+	for _, val := range vals {
+		if !utf8.ValidString(val) {
+			return fmt.Errorf("label value %q is not valid UTF-8", val)
+		}
+	}
+
+	return nil
+}
+
+func checkLabelName(l string) bool {
+	return model.LabelName(l).IsValid() && !strings.HasPrefix(l, reservedLabelPrefix)
+}

vendor/github.com/prometheus/client_golang/prometheus/metric.go

@@ -0,0 +1,166 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+import (
+	"strings"
+
+	dto "github.com/prometheus/client_model/go"
+)
+
+const separatorByte byte = 255
+
+// A Metric models a single sample value with its meta data being exported to
+// Prometheus. Implementations of Metric in this package are Gauge, Counter,
+// Histogram, Summary, and Untyped.
+type Metric interface {
+	// Desc returns the descriptor for the Metric. This method idempotently
+	// returns the same descriptor throughout the lifetime of the
+	// Metric. The returned descriptor is immutable by contract. A Metric
+	// unable to describe itself must return an invalid descriptor (created
+	// with NewInvalidDesc).
+	Desc() *Desc
+	// Write encodes the Metric into a "Metric" Protocol Buffer data
+	// transmission object.
+	//
+	// Metric implementations must observe concurrency safety as reads of
+	// this metric may occur at any time, and any blocking occurs at the
+	// expense of total performance of rendering all registered
+	// metrics. Ideally, Metric implementations should support concurrent
+	// readers.
+	//
+	// While populating dto.Metric, it is the responsibility of the
+	// implementation to ensure validity of the Metric protobuf (like valid
+	// UTF-8 strings or syntactically valid metric and label names). It is
+	// recommended to sort labels lexicographically. (Implementers may find
+	// LabelPairSorter useful for that.) Callers of Write should still make
+	// sure of sorting if they depend on it.
+	Write(*dto.Metric) error
+	// TODO(beorn7): The original rationale of passing in a pre-allocated
+	// dto.Metric protobuf to save allocations has disappeared. The
+	// signature of this method should be changed to "Write() (*dto.Metric,
+	// error)".
+}
+
+// Opts bundles the options for creating most Metric types. Each metric
+// implementation XXX has its own XXXOpts type, but in most cases, it is just be
+// an alias of this type (which might change when the requirement arises.)
+//
+// It is mandatory to set Name and Help to a non-empty string. All other fields
+// are optional and can safely be left at their zero value.
+type Opts struct {
+	// Namespace, Subsystem, and Name are components of the fully-qualified
+	// name of the Metric (created by joining these components with
+	// "_"). Only Name is mandatory, the others merely help structuring the
+	// name. Note that the fully-qualified name of the metric must be a
+	// valid Prometheus metric name.
+	Namespace string
+	Subsystem string
+	Name      string
+
+	// Help provides information about this metric. Mandatory!
+	//
+	// Metrics with the same fully-qualified name must have the same Help
+	// string.
+	Help string
+
+	// ConstLabels are used to attach fixed labels to this metric. Metrics
+	// with the same fully-qualified name must have the same label names in
+	// their ConstLabels.
+	//
+	// Note that in most cases, labels have a value that varies during the
+	// lifetime of a process. Those labels are usually managed with a metric
+	// vector collector (like CounterVec, GaugeVec, UntypedVec). ConstLabels
+	// serve only special purposes. One is for the special case where the
+	// value of a label does not change during the lifetime of a process,
+	// e.g. if the revision of the running binary is put into a
+	// label. Another, more advanced purpose is if more than one Collector
+	// needs to collect Metrics with the same fully-qualified name. In that
+	// case, those Metrics must differ in the values of their
+	// ConstLabels. See the Collector examples.
+	//
+	// If the value of a label never changes (not even between binaries),
+	// that label most likely should not be a label at all (but part of the
+	// metric name).
+	ConstLabels Labels
+}
+
+// BuildFQName joins the given three name components by "_". Empty name
+// components are ignored. If the name parameter itself is empty, an empty
+// string is returned, no matter what. Metric implementations included in this
+// library use this function internally to generate the fully-qualified metric
+// name from the name component in their Opts. Users of the library will only
+// need this function if they implement their own Metric or instantiate a Desc
+// (with NewDesc) directly.
+func BuildFQName(namespace, subsystem, name string) string {
+	if name == "" {
+		return ""
+	}
+	switch {
+	case namespace != "" && subsystem != "":
+		return strings.Join([]string{namespace, subsystem, name}, "_")
+	case namespace != "":
+		return strings.Join([]string{namespace, name}, "_")
+	case subsystem != "":
+		return strings.Join([]string{subsystem, name}, "_")
+	}
+	return name
+}
+
+// LabelPairSorter implements sort.Interface. It is used to sort a slice of
+// dto.LabelPair pointers. This is useful for implementing the Write method of
+// custom metrics.
+type LabelPairSorter []*dto.LabelPair
+
+func (s LabelPairSorter) Len() int {
+	return len(s)
+}
+
+func (s LabelPairSorter) Swap(i, j int) {
+	s[i], s[j] = s[j], s[i]
+}
+
+func (s LabelPairSorter) Less(i, j int) bool {
+	return s[i].GetName() < s[j].GetName()
+}
+
+type hashSorter []uint64
+
+func (s hashSorter) Len() int {
+	return len(s)
+}
+
+func (s hashSorter) Swap(i, j int) {
+	s[i], s[j] = s[j], s[i]
+}
+
+func (s hashSorter) Less(i, j int) bool {
+	return s[i] < s[j]
+}
+
+type invalidMetric struct {
+	desc *Desc
+	err  error
+}
+
+// NewInvalidMetric returns a metric whose Write method always returns the
+// provided error. It is useful if a Collector finds itself unable to collect
+// a metric and wishes to report an error to the registry.
+func NewInvalidMetric(desc *Desc, err error) Metric {
+	return &invalidMetric{desc, err}
+}
+
+func (m *invalidMetric) Desc() *Desc { return m.desc }
+
+func (m *invalidMetric) Write(*dto.Metric) error { return m.err }

vendor/github.com/prometheus/client_golang/prometheus/metric_test.go

@@ -0,0 +1,35 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+import "testing"
+
+func TestBuildFQName(t *testing.T) {
+	scenarios := []struct{ namespace, subsystem, name, result string }{
+		{"a", "b", "c", "a_b_c"},
+		{"", "b", "c", "b_c"},
+		{"a", "", "c", "a_c"},
+		{"", "", "c", "c"},
+		{"a", "b", "", ""},
+		{"a", "", "", ""},
+		{"", "b", "", ""},
+		{" ", "", "", ""},
+	}
+
+	for i, s := range scenarios {
+		if want, got := s.result, BuildFQName(s.namespace, s.subsystem, s.name); want != got {
+			t.Errorf("%d. want %s, got %s", i, want, got)
+		}
+	}
+}

vendor/github.com/prometheus/client_golang/prometheus/observer.go

@@ -0,0 +1,50 @@
+// Copyright 2017 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+// Observer is the interface that wraps the Observe method, which is used by
+// Histogram and Summary to add observations.
+type Observer interface {
+	Observe(float64)
+}
+
+// The ObserverFunc type is an adapter to allow the use of ordinary
+// functions as Observers. If f is a function with the appropriate
+// signature, ObserverFunc(f) is an Observer that calls f.
+//
+// This adapter is usually used in connection with the Timer type, and there are
+// two general use cases:
+//
+// The most common one is to use a Gauge as the Observer for a Timer.
+// See the "Gauge" Timer example.
+//
+// The more advanced use case is to create a function that dynamically decides
+// which Observer to use for observing the duration. See the "Complex" Timer
+// example.
+type ObserverFunc func(float64)
+
+// Observe calls f(value). It implements Observer.
+func (f ObserverFunc) Observe(value float64) {
+	f(value)
+}
+
+// ObserverVec is an interface implemented by `HistogramVec` and `SummaryVec`.
+type ObserverVec interface {
+	GetMetricWith(Labels) (Observer, error)
+	GetMetricWithLabelValues(lvs ...string) (Observer, error)
+	With(Labels) Observer
+	WithLabelValues(...string) Observer
+
+	Collector
+}

vendor/github.com/prometheus/client_golang/prometheus/process_collector.go

@@ -0,0 +1,140 @@
+// Copyright 2015 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+import "github.com/prometheus/procfs"
+
+type processCollector struct {
+	pid             int
+	collectFn       func(chan<- Metric)
+	pidFn           func() (int, error)
+	cpuTotal        *Desc
+	openFDs, maxFDs *Desc
+	vsize, rss      *Desc
+	startTime       *Desc
+}
+
+// NewProcessCollector returns a collector which exports the current state of
+// process metrics including cpu, memory and file descriptor usage as well as
+// the process start time for the given process id under the given namespace.
+func NewProcessCollector(pid int, namespace string) Collector {
+	return NewProcessCollectorPIDFn(
+		func() (int, error) { return pid, nil },
+		namespace,
+	)
+}
+
+// NewProcessCollectorPIDFn returns a collector which exports the current state
+// of process metrics including cpu, memory and file descriptor usage as well
+// as the process start time under the given namespace. The given pidFn is
+// called on each collect and is used to determine the process to export
+// metrics for.
+func NewProcessCollectorPIDFn(
+	pidFn func() (int, error),
+	namespace string,
+) Collector {
+	ns := ""
+	if len(namespace) > 0 {
+		ns = namespace + "_"
+	}
+
+	c := processCollector{
+		pidFn:     pidFn,
+		collectFn: func(chan<- Metric) {},
+
+		cpuTotal: NewDesc(
+			ns+"process_cpu_seconds_total",
+			"Total user and system CPU time spent in seconds.",
+			nil, nil,
+		),
+		openFDs: NewDesc(
+			ns+"process_open_fds",
+			"Number of open file descriptors.",
+			nil, nil,
+		),
+		maxFDs: NewDesc(
+			ns+"process_max_fds",
+			"Maximum number of open file descriptors.",
+			nil, nil,
+		),
+		vsize: NewDesc(
+			ns+"process_virtual_memory_bytes",
+			"Virtual memory size in bytes.",
+			nil, nil,
+		),
+		rss: NewDesc(
+			ns+"process_resident_memory_bytes",
+			"Resident memory size in bytes.",
+			nil, nil,
+		),
+		startTime: NewDesc(
+			ns+"process_start_time_seconds",
+			"Start time of the process since unix epoch in seconds.",
+			nil, nil,
+		),
+	}
+
+	// Set up process metric collection if supported by the runtime.
+	if _, err := procfs.NewStat(); err == nil {
+		c.collectFn = c.processCollect
+	}
+
+	return &c
+}
+
+// Describe returns all descriptions of the collector.
+func (c *processCollector) Describe(ch chan<- *Desc) {
+	ch <- c.cpuTotal
+	ch <- c.openFDs
+	ch <- c.maxFDs
+	ch <- c.vsize
+	ch <- c.rss
+	ch <- c.startTime
+}
+
+// Collect returns the current state of all metrics of the collector.
+func (c *processCollector) Collect(ch chan<- Metric) {
+	c.collectFn(ch)
+}
+
+// TODO(ts): Bring back error reporting by reverting 7faf9e7 as soon as the
+// client allows users to configure the error behavior.
+func (c *processCollector) processCollect(ch chan<- Metric) {
+	pid, err := c.pidFn()
+	if err != nil {
+		return
+	}
+
+	p, err := procfs.NewProc(pid)
+	if err != nil {
+		return
+	}
+
+	if stat, err := p.NewStat(); err == nil {
+		ch <- MustNewConstMetric(c.cpuTotal, CounterValue, stat.CPUTime())
+		ch <- MustNewConstMetric(c.vsize, GaugeValue, float64(stat.VirtualMemory()))
+		ch <- MustNewConstMetric(c.rss, GaugeValue, float64(stat.ResidentMemory()))
+		if startTime, err := stat.StartTime(); err == nil {
+			ch <- MustNewConstMetric(c.startTime, GaugeValue, startTime)
+		}
+	}
+
+	if fds, err := p.FileDescriptorsLen(); err == nil {
+		ch <- MustNewConstMetric(c.openFDs, GaugeValue, float64(fds))
+	}
+
+	if limits, err := p.NewLimits(); err == nil {
+		ch <- MustNewConstMetric(c.maxFDs, GaugeValue, float64(limits.OpenFiles))
+	}
+}

vendor/github.com/prometheus/client_golang/prometheus/process_collector_test.go

@@ -0,0 +1,58 @@
+package prometheus
+
+import (
+	"bytes"
+	"os"
+	"regexp"
+	"testing"
+
+	"github.com/prometheus/common/expfmt"
+	"github.com/prometheus/procfs"
+)
+
+func TestProcessCollector(t *testing.T) {
+	if _, err := procfs.Self(); err != nil {
+		t.Skipf("skipping TestProcessCollector, procfs not available: %s", err)
+	}
+
+	registry := NewRegistry()
+	if err := registry.Register(NewProcessCollector(os.Getpid(), "")); err != nil {
+		t.Fatal(err)
+	}
+	if err := registry.Register(NewProcessCollectorPIDFn(
+		func() (int, error) { return os.Getpid(), nil }, "foobar"),
+	); err != nil {
+		t.Fatal(err)
+	}
+
+	mfs, err := registry.Gather()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	var buf bytes.Buffer
+	for _, mf := range mfs {
+		if _, err := expfmt.MetricFamilyToText(&buf, mf); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	for _, re := range []*regexp.Regexp{
+		regexp.MustCompile("\nprocess_cpu_seconds_total [0-9]"),
+		regexp.MustCompile("\nprocess_max_fds [1-9]"),
+		regexp.MustCompile("\nprocess_open_fds [1-9]"),
+		regexp.MustCompile("\nprocess_virtual_memory_bytes [1-9]"),
+		regexp.MustCompile("\nprocess_resident_memory_bytes [1-9]"),
+		regexp.MustCompile("\nprocess_start_time_seconds [0-9.]{10,}"),
+		regexp.MustCompile("\nfoobar_process_cpu_seconds_total [0-9]"),
+		regexp.MustCompile("\nfoobar_process_max_fds [1-9]"),
+		regexp.MustCompile("\nfoobar_process_open_fds [1-9]"),
+		regexp.MustCompile("\nfoobar_process_virtual_memory_bytes [1-9]"),
+		regexp.MustCompile("\nfoobar_process_resident_memory_bytes [1-9]"),
+		regexp.MustCompile("\nfoobar_process_start_time_seconds [0-9.]{10,}"),
+	} {
+		if !re.Match(buf.Bytes()) {
+			t.Errorf("want body to match %s\n%s", re, buf.String())
+		}
+	}
+}

vendor/github.com/prometheus/client_golang/prometheus/promhttp/delegator.go

@@ -0,0 +1,199 @@
+// Copyright 2017 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package promhttp
+
+import (
+	"bufio"
+	"io"
+	"net"
+	"net/http"
+)
+
+const (
+	closeNotifier = 1 << iota
+	flusher
+	hijacker
+	readerFrom
+	pusher
+)
+
+type delegator interface {
+	http.ResponseWriter
+
+	Status() int
+	Written() int64
+}
+
+type responseWriterDelegator struct {
+	http.ResponseWriter
+
+	handler, method    string
+	status             int
+	written            int64
+	wroteHeader        bool
+	observeWriteHeader func(int)
+}
+
+func (r *responseWriterDelegator) Status() int {
+	return r.status
+}
+
+func (r *responseWriterDelegator) Written() int64 {
+	return r.written
+}
+
+func (r *responseWriterDelegator) WriteHeader(code int) {
+	r.status = code
+	r.wroteHeader = true
+	r.ResponseWriter.WriteHeader(code)
+	if r.observeWriteHeader != nil {
+		r.observeWriteHeader(code)
+	}
+}
+
+func (r *responseWriterDelegator) Write(b []byte) (int, error) {
+	if !r.wroteHeader {
+		r.WriteHeader(http.StatusOK)
+	}
+	n, err := r.ResponseWriter.Write(b)
+	r.written += int64(n)
+	return n, err
+}
+
+type closeNotifierDelegator struct{ *responseWriterDelegator }
+type flusherDelegator struct{ *responseWriterDelegator }
+type hijackerDelegator struct{ *responseWriterDelegator }
+type readerFromDelegator struct{ *responseWriterDelegator }
+
+func (d *closeNotifierDelegator) CloseNotify() <-chan bool {
+	return d.ResponseWriter.(http.CloseNotifier).CloseNotify()
+}
+func (d *flusherDelegator) Flush() {
+	d.ResponseWriter.(http.Flusher).Flush()
+}
+func (d *hijackerDelegator) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	return d.ResponseWriter.(http.Hijacker).Hijack()
+}
+func (d *readerFromDelegator) ReadFrom(re io.Reader) (int64, error) {
+	if !d.wroteHeader {
+		d.WriteHeader(http.StatusOK)
+	}
+	n, err := d.ResponseWriter.(io.ReaderFrom).ReadFrom(re)
+	d.written += n
+	return n, err
+}
+
+var pickDelegator = make([]func(*responseWriterDelegator) delegator, 32)
+
+func init() {
+	// TODO(beorn7): Code generation would help here.
+	pickDelegator[0] = func(d *responseWriterDelegator) delegator { // 0
+		return d
+	}
+	pickDelegator[closeNotifier] = func(d *responseWriterDelegator) delegator { // 1
+		return closeNotifierDelegator{d}
+	}
+	pickDelegator[flusher] = func(d *responseWriterDelegator) delegator { // 2
+		return flusherDelegator{d}
+	}
+	pickDelegator[flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 3
+		return struct {
+			*responseWriterDelegator
+			http.Flusher
+			http.CloseNotifier
+		}{d, &flusherDelegator{d}, &closeNotifierDelegator{d}}
+	}
+	pickDelegator[hijacker] = func(d *responseWriterDelegator) delegator { // 4
+		return hijackerDelegator{d}
+	}
+	pickDelegator[hijacker+closeNotifier] = func(d *responseWriterDelegator) delegator { // 5
+		return struct {
+			*responseWriterDelegator
+			http.Hijacker
+			http.CloseNotifier
+		}{d, &hijackerDelegator{d}, &closeNotifierDelegator{d}}
+	}
+	pickDelegator[hijacker+flusher] = func(d *responseWriterDelegator) delegator { // 6
+		return struct {
+			*responseWriterDelegator
+			http.Hijacker
+			http.Flusher
+		}{d, &hijackerDelegator{d}, &flusherDelegator{d}}
+	}
+	pickDelegator[hijacker+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 7
+		return struct {
+			*responseWriterDelegator
+			http.Hijacker
+			http.Flusher
+			http.CloseNotifier
+		}{d, &hijackerDelegator{d}, &flusherDelegator{d}, &closeNotifierDelegator{d}}
+	}
+	pickDelegator[readerFrom] = func(d *responseWriterDelegator) delegator { // 8
+		return readerFromDelegator{d}
+	}
+	pickDelegator[readerFrom+closeNotifier] = func(d *responseWriterDelegator) delegator { // 9
+		return struct {
+			*responseWriterDelegator
+			io.ReaderFrom
+			http.CloseNotifier
+		}{d, &readerFromDelegator{d}, &closeNotifierDelegator{d}}
+	}
+	pickDelegator[readerFrom+flusher] = func(d *responseWriterDelegator) delegator { // 10
+		return struct {
+			*responseWriterDelegator
+			io.ReaderFrom
+			http.Flusher
+		}{d, &readerFromDelegator{d}, &flusherDelegator{d}}
+	}
+	pickDelegator[readerFrom+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 11
+		return struct {
+			*responseWriterDelegator
+			io.ReaderFrom
+			http.Flusher
+			http.CloseNotifier
+		}{d, &readerFromDelegator{d}, &flusherDelegator{d}, &closeNotifierDelegator{d}}
+	}
+	pickDelegator[readerFrom+hijacker] = func(d *responseWriterDelegator) delegator { // 12
+		return struct {
+			*responseWriterDelegator
+			io.ReaderFrom
+			http.Hijacker
+		}{d, &readerFromDelegator{d}, &hijackerDelegator{d}}
+	}
+	pickDelegator[readerFrom+hijacker+closeNotifier] = func(d *responseWriterDelegator) delegator { // 13
+		return struct {
+			*responseWriterDelegator
+			io.ReaderFrom
+			http.Hijacker
+			http.CloseNotifier
+		}{d, &readerFromDelegator{d}, &hijackerDelegator{d}, &closeNotifierDelegator{d}}
+	}
+	pickDelegator[readerFrom+hijacker+flusher] = func(d *responseWriterDelegator) delegator { // 14
+		return struct {
+			*responseWriterDelegator
+			io.ReaderFrom
+			http.Hijacker
+			http.Flusher
+		}{d, &readerFromDelegator{d}, &hijackerDelegator{d}, &flusherDelegator{d}}
+	}
+	pickDelegator[readerFrom+hijacker+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 15
+		return struct {
+			*responseWriterDelegator
+			io.ReaderFrom
+			http.Hijacker
+			http.Flusher
+			http.CloseNotifier
+		}{d, &readerFromDelegator{d}, &hijackerDelegator{d}, &flusherDelegator{d}, &closeNotifierDelegator{d}}
+	}
+}

vendor/github.com/prometheus/client_golang/prometheus/promhttp/delegator_1_8.go

@@ -0,0 +1,181 @@
+// Copyright 2017 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build go1.8
+
+package promhttp
+
+import (
+	"io"
+	"net/http"
+)
+
+type pusherDelegator struct{ *responseWriterDelegator }
+
+func (d *pusherDelegator) Push(target string, opts *http.PushOptions) error {
+	return d.ResponseWriter.(http.Pusher).Push(target, opts)
+}
+
+func init() {
+	pickDelegator[pusher] = func(d *responseWriterDelegator) delegator { // 16
+		return pusherDelegator{d}
+	}
+	pickDelegator[pusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 17
+		return struct {
+			*responseWriterDelegator
+			http.Pusher
+			http.CloseNotifier
+		}{d, &pusherDelegator{d}, &closeNotifierDelegator{d}}
+	}
+	pickDelegator[pusher+flusher] = func(d *responseWriterDelegator) delegator { // 18
+		return struct {
+			*responseWriterDelegator
+			http.Pusher
+			http.Flusher
+		}{d, &pusherDelegator{d}, &flusherDelegator{d}}
+	}
+	pickDelegator[pusher+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 19
+		return struct {
+			*responseWriterDelegator
+			http.Pusher
+			http.Flusher
+			http.CloseNotifier
+		}{d, &pusherDelegator{d}, &flusherDelegator{d}, &closeNotifierDelegator{d}}
+	}
+	pickDelegator[pusher+hijacker] = func(d *responseWriterDelegator) delegator { // 20
+		return struct {
+			*responseWriterDelegator
+			http.Pusher
+			http.Hijacker
+		}{d, &pusherDelegator{d}, &hijackerDelegator{d}}
+	}
+	pickDelegator[pusher+hijacker+closeNotifier] = func(d *responseWriterDelegator) delegator { // 21
+		return struct {
+			*responseWriterDelegator
+			http.Pusher
+			http.Hijacker
+			http.CloseNotifier
+		}{d, &pusherDelegator{d}, &hijackerDelegator{d}, &closeNotifierDelegator{d}}
+	}
+	pickDelegator[pusher+hijacker+flusher] = func(d *responseWriterDelegator) delegator { // 22
+		return struct {
+			*responseWriterDelegator
+			http.Pusher
+			http.Hijacker
+			http.Flusher
+		}{d, &pusherDelegator{d}, &hijackerDelegator{d}, &flusherDelegator{d}}
+	}
+	pickDelegator[pusher+hijacker+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { //23
+		return struct {
+			*responseWriterDelegator
+			http.Pusher
+			http.Hijacker
+			http.Flusher
+			http.CloseNotifier
+		}{d, &pusherDelegator{d}, &hijackerDelegator{d}, &flusherDelegator{d}, &closeNotifierDelegator{d}}
+	}
+	pickDelegator[pusher+readerFrom] = func(d *responseWriterDelegator) delegator { // 24
+		return struct {
+			*responseWriterDelegator
+			http.Pusher
+			io.ReaderFrom
+		}{d, &pusherDelegator{d}, &readerFromDelegator{d}}
+	}
+	pickDelegator[pusher+readerFrom+closeNotifier] = func(d *responseWriterDelegator) delegator { // 25
+		return struct {
+			*responseWriterDelegator
+			http.Pusher
+			io.ReaderFrom
+			http.CloseNotifier
+		}{d, &pusherDelegator{d}, &readerFromDelegator{d}, &closeNotifierDelegator{d}}
+	}
+	pickDelegator[pusher+readerFrom+flusher] = func(d *responseWriterDelegator) delegator { // 26
+		return struct {
+			*responseWriterDelegator
+			http.Pusher
+			io.ReaderFrom
+			http.Flusher
+		}{d, &pusherDelegator{d}, &readerFromDelegator{d}, &flusherDelegator{d}}
+	}
+	pickDelegator[pusher+readerFrom+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 27
+		return struct {
+			*responseWriterDelegator
+			http.Pusher
+			io.ReaderFrom
+			http.Flusher
+			http.CloseNotifier
+		}{d, &pusherDelegator{d}, &readerFromDelegator{d}, &flusherDelegator{d}, &closeNotifierDelegator{d}}
+	}
+	pickDelegator[pusher+readerFrom+hijacker] = func(d *responseWriterDelegator) delegator { // 28
+		return struct {
+			*responseWriterDelegator
+			http.Pusher
+			io.ReaderFrom
+			http.Hijacker
+		}{d, &pusherDelegator{d}, &readerFromDelegator{d}, &hijackerDelegator{d}}
+	}
+	pickDelegator[pusher+readerFrom+hijacker+closeNotifier] = func(d *responseWriterDelegator) delegator { // 29
+		return struct {
+			*responseWriterDelegator
+			http.Pusher
+			io.ReaderFrom
+			http.Hijacker
+			http.CloseNotifier
+		}{d, &pusherDelegator{d}, &readerFromDelegator{d}, &hijackerDelegator{d}, &closeNotifierDelegator{d}}
+	}
+	pickDelegator[pusher+readerFrom+hijacker+flusher] = func(d *responseWriterDelegator) delegator { // 30
+		return struct {
+			*responseWriterDelegator
+			http.Pusher
+			io.ReaderFrom
+			http.Hijacker
+			http.Flusher
+		}{d, &pusherDelegator{d}, &readerFromDelegator{d}, &hijackerDelegator{d}, &flusherDelegator{d}}
+	}
+	pickDelegator[pusher+readerFrom+hijacker+flusher+closeNotifier] = func(d *responseWriterDelegator) delegator { // 31
+		return struct {
+			*responseWriterDelegator
+			http.Pusher
+			io.ReaderFrom
+			http.Hijacker
+			http.Flusher
+			http.CloseNotifier
+		}{d, &pusherDelegator{d}, &readerFromDelegator{d}, &hijackerDelegator{d}, &flusherDelegator{d}, &closeNotifierDelegator{d}}
+	}
+}
+
+func newDelegator(w http.ResponseWriter, observeWriteHeaderFunc func(int)) delegator {
+	d := &responseWriterDelegator{
+		ResponseWriter:     w,
+		observeWriteHeader: observeWriteHeaderFunc,
+	}
+
+	id := 0
+	if _, ok := w.(http.CloseNotifier); ok {
+		id += closeNotifier
+	}
+	if _, ok := w.(http.Flusher); ok {
+		id += flusher
+	}
+	if _, ok := w.(http.Hijacker); ok {
+		id += hijacker
+	}
+	if _, ok := w.(io.ReaderFrom); ok {
+		id += readerFrom
+	}
+	if _, ok := w.(http.Pusher); ok {
+		id += pusher
+	}
+
+	return pickDelegator[id](d)
+}

vendor/github.com/prometheus/client_golang/prometheus/promhttp/delegator_pre_1_8.go

@@ -0,0 +1,44 @@
+// Copyright 2017 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build !go1.8
+
+package promhttp
+
+import (
+	"io"
+	"net/http"
+)
+
+func newDelegator(w http.ResponseWriter, observeWriteHeaderFunc func(int)) delegator {
+	d := &responseWriterDelegator{
+		ResponseWriter:     w,
+		observeWriteHeader: observeWriteHeaderFunc,
+	}
+
+	id := 0
+	if _, ok := w.(http.CloseNotifier); ok {
+		id += closeNotifier
+	}
+	if _, ok := w.(http.Flusher); ok {
+		id += flusher
+	}
+	if _, ok := w.(http.Hijacker); ok {
+		id += hijacker
+	}
+	if _, ok := w.(io.ReaderFrom); ok {
+		id += readerFrom
+	}
+
+	return pickDelegator[id](d)
+}

vendor/github.com/prometheus/client_golang/prometheus/promhttp/http.go

@@ -0,0 +1,204 @@
+// Copyright 2016 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package promhttp provides tooling around HTTP servers and clients.
+//
+// First, the package allows the creation of http.Handler instances to expose
+// Prometheus metrics via HTTP. promhttp.Handler acts on the
+// prometheus.DefaultGatherer. With HandlerFor, you can create a handler for a
+// custom registry or anything that implements the Gatherer interface. It also
+// allows the creation of handlers that act differently on errors or allow to
+// log errors.
+//
+// Second, the package provides tooling to instrument instances of http.Handler
+// via middleware. Middleware wrappers follow the naming scheme
+// InstrumentHandlerX, where X describes the intended use of the middleware.
+// See each function's doc comment for specific details.
+//
+// Finally, the package allows for an http.RoundTripper to be instrumented via
+// middleware. Middleware wrappers follow the naming scheme
+// InstrumentRoundTripperX, where X describes the intended use of the
+// middleware. See each function's doc comment for specific details.
+package promhttp
+
+import (
+	"bytes"
+	"compress/gzip"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+	"sync"
+
+	"github.com/prometheus/common/expfmt"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const (
+	contentTypeHeader     = "Content-Type"
+	contentLengthHeader   = "Content-Length"
+	contentEncodingHeader = "Content-Encoding"
+	acceptEncodingHeader  = "Accept-Encoding"
+)
+
+var bufPool sync.Pool
+
+func getBuf() *bytes.Buffer {
+	buf := bufPool.Get()
+	if buf == nil {
+		return &bytes.Buffer{}
+	}
+	return buf.(*bytes.Buffer)
+}
+
+func giveBuf(buf *bytes.Buffer) {
+	buf.Reset()
+	bufPool.Put(buf)
+}
+
+// Handler returns an HTTP handler for the prometheus.DefaultGatherer. The
+// Handler uses the default HandlerOpts, i.e. report the first error as an HTTP
+// error, no error logging, and compression if requested by the client.
+//
+// If you want to create a Handler for the DefaultGatherer with different
+// HandlerOpts, create it with HandlerFor with prometheus.DefaultGatherer and
+// your desired HandlerOpts.
+func Handler() http.Handler {
+	return HandlerFor(prometheus.DefaultGatherer, HandlerOpts{})
+}
+
+// HandlerFor returns an http.Handler for the provided Gatherer. The behavior
+// of the Handler is defined by the provided HandlerOpts.
+func HandlerFor(reg prometheus.Gatherer, opts HandlerOpts) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
+		mfs, err := reg.Gather()
+		if err != nil {
+			if opts.ErrorLog != nil {
+				opts.ErrorLog.Println("error gathering metrics:", err)
+			}
+			switch opts.ErrorHandling {
+			case PanicOnError:
+				panic(err)
+			case ContinueOnError:
+				if len(mfs) == 0 {
+					http.Error(w, "No metrics gathered, last error:\n\n"+err.Error(), http.StatusInternalServerError)
+					return
+				}
+			case HTTPErrorOnError:
+				http.Error(w, "An error has occurred during metrics gathering:\n\n"+err.Error(), http.StatusInternalServerError)
+				return
+			}
+		}
+
+		contentType := expfmt.Negotiate(req.Header)
+		buf := getBuf()
+		defer giveBuf(buf)
+		writer, encoding := decorateWriter(req, buf, opts.DisableCompression)
+		enc := expfmt.NewEncoder(writer, contentType)
+		var lastErr error
+		for _, mf := range mfs {
+			if err := enc.Encode(mf); err != nil {
+				lastErr = err
+				if opts.ErrorLog != nil {
+					opts.ErrorLog.Println("error encoding metric family:", err)
+				}
+				switch opts.ErrorHandling {
+				case PanicOnError:
+					panic(err)
+				case ContinueOnError:
+					// Handled later.
+				case HTTPErrorOnError:
+					http.Error(w, "An error has occurred during metrics encoding:\n\n"+err.Error(), http.StatusInternalServerError)
+					return
+				}
+			}
+		}
+		if closer, ok := writer.(io.Closer); ok {
+			closer.Close()
+		}
+		if lastErr != nil && buf.Len() == 0 {
+			http.Error(w, "No metrics encoded, last error:\n\n"+lastErr.Error(), http.StatusInternalServerError)
+			return
+		}
+		header := w.Header()
+		header.Set(contentTypeHeader, string(contentType))
+		header.Set(contentLengthHeader, fmt.Sprint(buf.Len()))
+		if encoding != "" {
+			header.Set(contentEncodingHeader, encoding)
+		}
+		w.Write(buf.Bytes())
+		// TODO(beorn7): Consider streaming serving of metrics.
+	})
+}
+
+// HandlerErrorHandling defines how a Handler serving metrics will handle
+// errors.
+type HandlerErrorHandling int
+
+// These constants cause handlers serving metrics to behave as described if
+// errors are encountered.
+const (
+	// Serve an HTTP status code 500 upon the first error
+	// encountered. Report the error message in the body.
+	HTTPErrorOnError HandlerErrorHandling = iota
+	// Ignore errors and try to serve as many metrics as possible.  However,
+	// if no metrics can be served, serve an HTTP status code 500 and the
+	// last error message in the body. Only use this in deliberate "best
+	// effort" metrics collection scenarios. It is recommended to at least
+	// log errors (by providing an ErrorLog in HandlerOpts) to not mask
+	// errors completely.
+	ContinueOnError
+	// Panic upon the first error encountered (useful for "crash only" apps).
+	PanicOnError
+)
+
+// Logger is the minimal interface HandlerOpts needs for logging. Note that
+// log.Logger from the standard library implements this interface, and it is
+// easy to implement by custom loggers, if they don't do so already anyway.
+type Logger interface {
+	Println(v ...interface{})
+}
+
+// HandlerOpts specifies options how to serve metrics via an http.Handler. The
+// zero value of HandlerOpts is a reasonable default.
+type HandlerOpts struct {
+	// ErrorLog specifies an optional logger for errors collecting and
+	// serving metrics. If nil, errors are not logged at all.
+	ErrorLog Logger
+	// ErrorHandling defines how errors are handled. Note that errors are
+	// logged regardless of the configured ErrorHandling provided ErrorLog
+	// is not nil.
+	ErrorHandling HandlerErrorHandling
+	// If DisableCompression is true, the handler will never compress the
+	// response, even if requested by the client.
+	DisableCompression bool
+}
+
+// decorateWriter wraps a writer to handle gzip compression if requested.  It
+// returns the decorated writer and the appropriate "Content-Encoding" header
+// (which is empty if no compression is enabled).
+func decorateWriter(request *http.Request, writer io.Writer, compressionDisabled bool) (io.Writer, string) {
+	if compressionDisabled {
+		return writer, ""
+	}
+	header := request.Header.Get(acceptEncodingHeader)
+	parts := strings.Split(header, ",")
+	for _, part := range parts {
+		part := strings.TrimSpace(part)
+		if part == "gzip" || strings.HasPrefix(part, "gzip;") {
+			return gzip.NewWriter(writer), "gzip"
+		}
+	}
+	return writer, ""
+}

vendor/github.com/prometheus/client_golang/prometheus/promhttp/http_test.go

@@ -0,0 +1,131 @@
+// Copyright 2016 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package promhttp
+
+import (
+	"bytes"
+	"errors"
+	"log"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+type errorCollector struct{}
+
+func (e errorCollector) Describe(ch chan<- *prometheus.Desc) {
+	ch <- prometheus.NewDesc("invalid_metric", "not helpful", nil, nil)
+}
+
+func (e errorCollector) Collect(ch chan<- prometheus.Metric) {
+	ch <- prometheus.NewInvalidMetric(
+		prometheus.NewDesc("invalid_metric", "not helpful", nil, nil),
+		errors.New("collect error"),
+	)
+}
+
+func TestHandlerErrorHandling(t *testing.T) {
+
+	// Create a registry that collects a MetricFamily with two elements,
+	// another with one, and reports an error.
+	reg := prometheus.NewRegistry()
+
+	cnt := prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "the_count",
+		Help: "Ah-ah-ah! Thunder and lightning!",
+	})
+	reg.MustRegister(cnt)
+
+	cntVec := prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name:        "name",
+			Help:        "docstring",
+			ConstLabels: prometheus.Labels{"constname": "constvalue"},
+		},
+		[]string{"labelname"},
+	)
+	cntVec.WithLabelValues("val1").Inc()
+	cntVec.WithLabelValues("val2").Inc()
+	reg.MustRegister(cntVec)
+
+	reg.MustRegister(errorCollector{})
+
+	logBuf := &bytes.Buffer{}
+	logger := log.New(logBuf, "", 0)
+
+	writer := httptest.NewRecorder()
+	request, _ := http.NewRequest("GET", "/", nil)
+	request.Header.Add("Accept", "test/plain")
+
+	errorHandler := HandlerFor(reg, HandlerOpts{
+		ErrorLog:      logger,
+		ErrorHandling: HTTPErrorOnError,
+	})
+	continueHandler := HandlerFor(reg, HandlerOpts{
+		ErrorLog:      logger,
+		ErrorHandling: ContinueOnError,
+	})
+	panicHandler := HandlerFor(reg, HandlerOpts{
+		ErrorLog:      logger,
+		ErrorHandling: PanicOnError,
+	})
+	wantMsg := `error gathering metrics: error collecting metric Desc{fqName: "invalid_metric", help: "not helpful", constLabels: {}, variableLabels: []}: collect error
+`
+	wantErrorBody := `An error has occurred during metrics gathering:
+
+error collecting metric Desc{fqName: "invalid_metric", help: "not helpful", constLabels: {}, variableLabels: []}: collect error
+`
+	wantOKBody := `# HELP name docstring
+# TYPE name counter
+name{constname="constvalue",labelname="val1"} 1
+name{constname="constvalue",labelname="val2"} 1
+# HELP the_count Ah-ah-ah! Thunder and lightning!
+# TYPE the_count counter
+the_count 0
+`
+
+	errorHandler.ServeHTTP(writer, request)
+	if got, want := writer.Code, http.StatusInternalServerError; got != want {
+		t.Errorf("got HTTP status code %d, want %d", got, want)
+	}
+	if got := logBuf.String(); got != wantMsg {
+		t.Errorf("got log message:\n%s\nwant log mesage:\n%s\n", got, wantMsg)
+	}
+	if got := writer.Body.String(); got != wantErrorBody {
+		t.Errorf("got body:\n%s\nwant body:\n%s\n", got, wantErrorBody)
+	}
+	logBuf.Reset()
+	writer.Body.Reset()
+	writer.Code = http.StatusOK
+
+	continueHandler.ServeHTTP(writer, request)
+	if got, want := writer.Code, http.StatusOK; got != want {
+		t.Errorf("got HTTP status code %d, want %d", got, want)
+	}
+	if got := logBuf.String(); got != wantMsg {
+		t.Errorf("got log message %q, want %q", got, wantMsg)
+	}
+	if got := writer.Body.String(); got != wantOKBody {
+		t.Errorf("got body %q, want %q", got, wantOKBody)
+	}
+
+	defer func() {
+		if err := recover(); err == nil {
+			t.Error("expected panic from panicHandler")
+		}
+	}()
+	panicHandler.ServeHTTP(writer, request)
+}

vendor/github.com/prometheus/client_golang/prometheus/promhttp/instrument_client.go

@@ -0,0 +1,98 @@
+// Copyright 2017 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package promhttp
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+// The RoundTripperFunc type is an adapter to allow the use of ordinary
+// functions as RoundTrippers. If f is a function with the appropriate
+// signature, RountTripperFunc(f) is a RoundTripper that calls f.
+type RoundTripperFunc func(req *http.Request) (*http.Response, error)
+
+// RoundTrip implements the RoundTripper interface.
+func (rt RoundTripperFunc) RoundTrip(r *http.Request) (*http.Response, error) {
+	return rt(r)
+}
+
+// InstrumentRoundTripperInFlight is a middleware that wraps the provided
+// http.RoundTripper. It sets the provided prometheus.Gauge to the number of
+// requests currently handled by the wrapped http.RoundTripper.
+//
+// See the example for ExampleInstrumentRoundTripperDuration for example usage.
+func InstrumentRoundTripperInFlight(gauge prometheus.Gauge, next http.RoundTripper) RoundTripperFunc {
+	return RoundTripperFunc(func(r *http.Request) (*http.Response, error) {
+		gauge.Inc()
+		defer gauge.Dec()
+		return next.RoundTrip(r)
+	})
+}
+
+// InstrumentRoundTripperCounter is a middleware that wraps the provided
+// http.RoundTripper to observe the request result with the provided CounterVec.
+// The CounterVec must have zero, one, or two labels. The only allowed label
+// names are "code" and "method". The function panics if any other instance
+// labels are provided. Partitioning of the CounterVec happens by HTTP status
+// code and/or HTTP method if the respective instance label names are present
+// in the CounterVec. For unpartitioned counting, use a CounterVec with
+// zero labels.
+//
+// If the wrapped RoundTripper panics or returns a non-nil error, the Counter
+// is not incremented.
+//
+// See the example for ExampleInstrumentRoundTripperDuration for example usage.
+func InstrumentRoundTripperCounter(counter *prometheus.CounterVec, next http.RoundTripper) RoundTripperFunc {
+	code, method := checkLabels(counter)
+
+	return RoundTripperFunc(func(r *http.Request) (*http.Response, error) {
+		resp, err := next.RoundTrip(r)
+		if err == nil {
+			counter.With(labels(code, method, r.Method, resp.StatusCode)).Inc()
+		}
+		return resp, err
+	})
+}
+
+// InstrumentRoundTripperDuration is a middleware that wraps the provided
+// http.RoundTripper to observe the request duration with the provided ObserverVec.
+// The ObserverVec must have zero, one, or two labels. The only allowed label
+// names are "code" and "method". The function panics if any other instance
+// labels are provided. The Observe method of the Observer in the ObserverVec
+// is called with the request duration in seconds. Partitioning happens by HTTP
+// status code and/or HTTP method if the respective instance label names are
+// present in the ObserverVec. For unpartitioned observations, use an
+// ObserverVec with zero labels. Note that partitioning of Histograms is
+// expensive and should be used judiciously.
+//
+// If the wrapped RoundTripper panics or returns a non-nil error, no values are
+// reported.
+//
+// Note that this method is only guaranteed to never observe negative durations
+// if used with Go1.9+.
+func InstrumentRoundTripperDuration(obs prometheus.ObserverVec, next http.RoundTripper) RoundTripperFunc {
+	code, method := checkLabels(obs)
+
+	return RoundTripperFunc(func(r *http.Request) (*http.Response, error) {
+		start := time.Now()
+		resp, err := next.RoundTrip(r)
+		if err == nil {
+			obs.With(labels(code, method, r.Method, resp.StatusCode)).Observe(time.Since(start).Seconds())
+		}
+		return resp, err
+	})
+}

vendor/github.com/prometheus/client_golang/prometheus/promhttp/instrument_client_1_8.go

@@ -0,0 +1,144 @@
+// Copyright 2017 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build go1.8
+
+package promhttp
+
+import (
+	"context"
+	"crypto/tls"
+	"net/http"
+	"net/http/httptrace"
+	"time"
+)
+
+// InstrumentTrace is used to offer flexibility in instrumenting the available
+// httptrace.ClientTrace hook functions. Each function is passed a float64
+// representing the time in seconds since the start of the http request. A user
+// may choose to use separately buckets Histograms, or implement custom
+// instance labels on a per function basis.
+type InstrumentTrace struct {
+	GotConn              func(float64)
+	PutIdleConn          func(float64)
+	GotFirstResponseByte func(float64)
+	Got100Continue       func(float64)
+	DNSStart             func(float64)
+	DNSDone              func(float64)
+	ConnectStart         func(float64)
+	ConnectDone          func(float64)
+	TLSHandshakeStart    func(float64)
+	TLSHandshakeDone     func(float64)
+	WroteHeaders         func(float64)
+	Wait100Continue      func(float64)
+	WroteRequest         func(float64)
+}
+
+// InstrumentRoundTripperTrace is a middleware that wraps the provided
+// RoundTripper and reports times to hook functions provided in the
+// InstrumentTrace struct. Hook functions that are not present in the provided
+// InstrumentTrace struct are ignored. Times reported to the hook functions are
+// time since the start of the request. Only with Go1.9+, those times are
+// guaranteed to never be negative. (Earlier Go versions are not using a
+// monotonic clock.) Note that partitioning of Histograms is expensive and
+// should be used judiciously.
+//
+// For hook functions that receive an error as an argument, no observations are
+// made in the event of a non-nil error value.
+//
+// See the example for ExampleInstrumentRoundTripperDuration for example usage.
+func InstrumentRoundTripperTrace(it *InstrumentTrace, next http.RoundTripper) RoundTripperFunc {
+	return RoundTripperFunc(func(r *http.Request) (*http.Response, error) {
+		start := time.Now()
+
+		trace := &httptrace.ClientTrace{
+			GotConn: func(_ httptrace.GotConnInfo) {
+				if it.GotConn != nil {
+					it.GotConn(time.Since(start).Seconds())
+				}
+			},
+			PutIdleConn: func(err error) {
+				if err != nil {
+					return
+				}
+				if it.PutIdleConn != nil {
+					it.PutIdleConn(time.Since(start).Seconds())
+				}
+			},
+			DNSStart: func(_ httptrace.DNSStartInfo) {
+				if it.DNSStart != nil {
+					it.DNSStart(time.Since(start).Seconds())
+				}
+			},
+			DNSDone: func(_ httptrace.DNSDoneInfo) {
+				if it.DNSStart != nil {
+					it.DNSStart(time.Since(start).Seconds())
+				}
+			},
+			ConnectStart: func(_, _ string) {
+				if it.ConnectStart != nil {
+					it.ConnectStart(time.Since(start).Seconds())
+				}
+			},
+			ConnectDone: func(_, _ string, err error) {
+				if err != nil {
+					return
+				}
+				if it.ConnectDone != nil {
+					it.ConnectDone(time.Since(start).Seconds())
+				}
+			},
+			GotFirstResponseByte: func() {
+				if it.GotFirstResponseByte != nil {
+					it.GotFirstResponseByte(time.Since(start).Seconds())
+				}
+			},
+			Got100Continue: func() {
+				if it.Got100Continue != nil {
+					it.Got100Continue(time.Since(start).Seconds())
+				}
+			},
+			TLSHandshakeStart: func() {
+				if it.TLSHandshakeStart != nil {
+					it.TLSHandshakeStart(time.Since(start).Seconds())
+				}
+			},
+			TLSHandshakeDone: func(_ tls.ConnectionState, err error) {
+				if err != nil {
+					return
+				}
+				if it.TLSHandshakeDone != nil {
+					it.TLSHandshakeDone(time.Since(start).Seconds())
+				}
+			},
+			WroteHeaders: func() {
+				if it.WroteHeaders != nil {
+					it.WroteHeaders(time.Since(start).Seconds())
+				}
+			},
+			Wait100Continue: func() {
+				if it.Wait100Continue != nil {
+					it.Wait100Continue(time.Since(start).Seconds())
+				}
+			},
+			WroteRequest: func(_ httptrace.WroteRequestInfo) {
+				if it.WroteRequest != nil {
+					it.WroteRequest(time.Since(start).Seconds())
+				}
+			},
+		}
+		r = r.WithContext(httptrace.WithClientTrace(context.Background(), trace))
+
+		return next.RoundTrip(r)
+	})
+}

vendor/github.com/prometheus/client_golang/prometheus/promhttp/instrument_client_1_8_test.go

@@ -0,0 +1,195 @@
+// Copyright 2017 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build go1.8
+
+package promhttp
+
+import (
+	"log"
+	"net/http"
+	"testing"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+func TestClientMiddlewareAPI(t *testing.T) {
+	client := http.DefaultClient
+	client.Timeout = 1 * time.Second
+
+	reg := prometheus.NewRegistry()
+
+	inFlightGauge := prometheus.NewGauge(prometheus.GaugeOpts{
+		Name: "client_in_flight_requests",
+		Help: "A gauge of in-flight requests for the wrapped client.",
+	})
+
+	counter := prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "client_api_requests_total",
+			Help: "A counter for requests from the wrapped client.",
+		},
+		[]string{"code", "method"},
+	)
+
+	dnsLatencyVec := prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name:    "dns_duration_seconds",
+			Help:    "Trace dns latency histogram.",
+			Buckets: []float64{.005, .01, .025, .05},
+		},
+		[]string{"event"},
+	)
+
+	tlsLatencyVec := prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name:    "tls_duration_seconds",
+			Help:    "Trace tls latency histogram.",
+			Buckets: []float64{.05, .1, .25, .5},
+		},
+		[]string{"event"},
+	)
+
+	histVec := prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name:    "request_duration_seconds",
+			Help:    "A histogram of request latencies.",
+			Buckets: prometheus.DefBuckets,
+		},
+		[]string{"method"},
+	)
+
+	reg.MustRegister(counter, tlsLatencyVec, dnsLatencyVec, histVec, inFlightGauge)
+
+	trace := &InstrumentTrace{
+		DNSStart: func(t float64) {
+			dnsLatencyVec.WithLabelValues("dns_start")
+		},
+		DNSDone: func(t float64) {
+			dnsLatencyVec.WithLabelValues("dns_done")
+		},
+		TLSHandshakeStart: func(t float64) {
+			tlsLatencyVec.WithLabelValues("tls_handshake_start")
+		},
+		TLSHandshakeDone: func(t float64) {
+			tlsLatencyVec.WithLabelValues("tls_handshake_done")
+		},
+	}
+
+	client.Transport = InstrumentRoundTripperInFlight(inFlightGauge,
+		InstrumentRoundTripperCounter(counter,
+			InstrumentRoundTripperTrace(trace,
+				InstrumentRoundTripperDuration(histVec, http.DefaultTransport),
+			),
+		),
+	)
+
+	resp, err := client.Get("http://google.com")
+	if err != nil {
+		t.Fatalf("%v", err)
+	}
+	defer resp.Body.Close()
+}
+
+func ExampleInstrumentRoundTripperDuration() {
+	client := http.DefaultClient
+	client.Timeout = 1 * time.Second
+
+	inFlightGauge := prometheus.NewGauge(prometheus.GaugeOpts{
+		Name: "client_in_flight_requests",
+		Help: "A gauge of in-flight requests for the wrapped client.",
+	})
+
+	counter := prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "client_api_requests_total",
+			Help: "A counter for requests from the wrapped client.",
+		},
+		[]string{"code", "method"},
+	)
+
+	// dnsLatencyVec uses custom buckets based on expected dns durations.
+	// It has an instance label "event", which is set in the
+	// DNSStart and DNSDonehook functions defined in the
+	// InstrumentTrace struct below.
+	dnsLatencyVec := prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name:    "dns_duration_seconds",
+			Help:    "Trace dns latency histogram.",
+			Buckets: []float64{.005, .01, .025, .05},
+		},
+		[]string{"event"},
+	)
+
+	// tlsLatencyVec uses custom buckets based on expected tls durations.
+	// It has an instance label "event", which is set in the
+	// TLSHandshakeStart and TLSHandshakeDone hook functions defined in the
+	// InstrumentTrace struct below.
+	tlsLatencyVec := prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name:    "tls_duration_seconds",
+			Help:    "Trace tls latency histogram.",
+			Buckets: []float64{.05, .1, .25, .5},
+		},
+		[]string{"event"},
+	)
+
+	// histVec has no labels, making it a zero-dimensional ObserverVec.
+	histVec := prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name:    "request_duration_seconds",
+			Help:    "A histogram of request latencies.",
+			Buckets: prometheus.DefBuckets,
+		},
+		[]string{},
+	)
+
+	// Register all of the metrics in the standard registry.
+	prometheus.MustRegister(counter, tlsLatencyVec, dnsLatencyVec, histVec, inFlightGauge)
+
+	// Define functions for the available httptrace.ClientTrace hook
+	// functions that we want to instrument.
+	trace := &InstrumentTrace{
+		DNSStart: func(t float64) {
+			dnsLatencyVec.WithLabelValues("dns_start")
+		},
+		DNSDone: func(t float64) {
+			dnsLatencyVec.WithLabelValues("dns_done")
+		},
+		TLSHandshakeStart: func(t float64) {
+			tlsLatencyVec.WithLabelValues("tls_handshake_start")
+		},
+		TLSHandshakeDone: func(t float64) {
+			tlsLatencyVec.WithLabelValues("tls_handshake_done")
+		},
+	}
+
+	// Wrap the default RoundTripper with middleware.
+	roundTripper := InstrumentRoundTripperInFlight(inFlightGauge,
+		InstrumentRoundTripperCounter(counter,
+			InstrumentRoundTripperTrace(trace,
+				InstrumentRoundTripperDuration(histVec, http.DefaultTransport),
+			),
+		),
+	)
+
+	// Set the RoundTripper on our client.
+	client.Transport = roundTripper
+
+	resp, err := client.Get("http://google.com")
+	if err != nil {
+		log.Printf("error: %v", err)
+	}
+	defer resp.Body.Close()
+}

vendor/github.com/prometheus/client_golang/prometheus/promhttp/instrument_server.go

@@ -0,0 +1,440 @@
+// Copyright 2017 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package promhttp
+
+import (
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	dto "github.com/prometheus/client_model/go"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+// magicString is used for the hacky label test in checkLabels. Remove once fixed.
+const magicString = "zZgWfBxLqvG8kc8IMv3POi2Bb0tZI3vAnBx+gBaFi9FyPzB/CzKUer1yufDa"
+
+// InstrumentHandlerInFlight is a middleware that wraps the provided
+// http.Handler. It sets the provided prometheus.Gauge to the number of
+// requests currently handled by the wrapped http.Handler.
+//
+// See the example for InstrumentHandlerDuration for example usage.
+func InstrumentHandlerInFlight(g prometheus.Gauge, next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		g.Inc()
+		defer g.Dec()
+		next.ServeHTTP(w, r)
+	})
+}
+
+// InstrumentHandlerDuration is a middleware that wraps the provided
+// http.Handler to observe the request duration with the provided ObserverVec.
+// The ObserverVec must have zero, one, or two labels. The only allowed label
+// names are "code" and "method". The function panics if any other instance
+// labels are provided. The Observe method of the Observer in the ObserverVec
+// is called with the request duration in seconds. Partitioning happens by HTTP
+// status code and/or HTTP method if the respective instance label names are
+// present in the ObserverVec. For unpartitioned observations, use an
+// ObserverVec with zero labels. Note that partitioning of Histograms is
+// expensive and should be used judiciously.
+//
+// If the wrapped Handler does not set a status code, a status code of 200 is assumed.
+//
+// If the wrapped Handler panics, no values are reported.
+//
+// Note that this method is only guaranteed to never observe negative durations
+// if used with Go1.9+.
+func InstrumentHandlerDuration(obs prometheus.ObserverVec, next http.Handler) http.HandlerFunc {
+	code, method := checkLabels(obs)
+
+	if code {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			now := time.Now()
+			d := newDelegator(w, nil)
+			next.ServeHTTP(d, r)
+
+			obs.With(labels(code, method, r.Method, d.Status())).Observe(time.Since(now).Seconds())
+		})
+	}
+
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		now := time.Now()
+		next.ServeHTTP(w, r)
+		obs.With(labels(code, method, r.Method, 0)).Observe(time.Since(now).Seconds())
+	})
+}
+
+// InstrumentHandlerCounter is a middleware that wraps the provided
+// http.Handler to observe the request result with the provided CounterVec.
+// The CounterVec must have zero, one, or two labels. The only allowed label
+// names are "code" and "method". The function panics if any other instance
+// labels are provided. Partitioning of the CounterVec happens by HTTP status
+// code and/or HTTP method if the respective instance label names are present
+// in the CounterVec. For unpartitioned counting, use a CounterVec with
+// zero labels.
+//
+// If the wrapped Handler does not set a status code, a status code of 200 is assumed.
+//
+// If the wrapped Handler panics, the Counter is not incremented.
+//
+// See the example for InstrumentHandlerDuration for example usage.
+func InstrumentHandlerCounter(counter *prometheus.CounterVec, next http.Handler) http.HandlerFunc {
+	code, method := checkLabels(counter)
+
+	if code {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			d := newDelegator(w, nil)
+			next.ServeHTTP(d, r)
+			counter.With(labels(code, method, r.Method, d.Status())).Inc()
+		})
+	}
+
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		next.ServeHTTP(w, r)
+		counter.With(labels(code, method, r.Method, 0)).Inc()
+	})
+}
+
+// InstrumentHandlerTimeToWriteHeader is a middleware that wraps the provided
+// http.Handler to observe with the provided ObserverVec the request duration
+// until the response headers are written. The ObserverVec must have zero, one,
+// or two labels. The only allowed label names are "code" and "method". The
+// function panics if any other instance labels are provided. The Observe
+// method of the Observer in the ObserverVec is called with the request
+// duration in seconds. Partitioning happens by HTTP status code and/or HTTP
+// method if the respective instance label names are present in the
+// ObserverVec. For unpartitioned observations, use an ObserverVec with zero
+// labels. Note that partitioning of Histograms is expensive and should be used
+// judiciously.
+//
+// If the wrapped Handler panics before calling WriteHeader, no value is
+// reported.
+//
+// Note that this method is only guaranteed to never observe negative durations
+// if used with Go1.9+.
+//
+// See the example for InstrumentHandlerDuration for example usage.
+func InstrumentHandlerTimeToWriteHeader(obs prometheus.ObserverVec, next http.Handler) http.HandlerFunc {
+	code, method := checkLabels(obs)
+
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		now := time.Now()
+		d := newDelegator(w, func(status int) {
+			obs.With(labels(code, method, r.Method, status)).Observe(time.Since(now).Seconds())
+		})
+		next.ServeHTTP(d, r)
+	})
+}
+
+// InstrumentHandlerRequestSize is a middleware that wraps the provided
+// http.Handler to observe the request size with the provided ObserverVec.
+// The ObserverVec must have zero, one, or two labels. The only allowed label
+// names are "code" and "method". The function panics if any other instance
+// labels are provided. The Observe method of the Observer in the ObserverVec
+// is called with the request size in bytes. Partitioning happens by HTTP
+// status code and/or HTTP method if the respective instance label names are
+// present in the ObserverVec. For unpartitioned observations, use an
+// ObserverVec with zero labels. Note that partitioning of Histograms is
+// expensive and should be used judiciously.
+//
+// If the wrapped Handler does not set a status code, a status code of 200 is assumed.
+//
+// If the wrapped Handler panics, no values are reported.
+//
+// See the example for InstrumentHandlerDuration for example usage.
+func InstrumentHandlerRequestSize(obs prometheus.ObserverVec, next http.Handler) http.HandlerFunc {
+	code, method := checkLabels(obs)
+
+	if code {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			d := newDelegator(w, nil)
+			next.ServeHTTP(d, r)
+			size := computeApproximateRequestSize(r)
+			obs.With(labels(code, method, r.Method, d.Status())).Observe(float64(size))
+		})
+	}
+
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		next.ServeHTTP(w, r)
+		size := computeApproximateRequestSize(r)
+		obs.With(labels(code, method, r.Method, 0)).Observe(float64(size))
+	})
+}
+
+// InstrumentHandlerResponseSize is a middleware that wraps the provided
+// http.Handler to observe the response size with the provided ObserverVec.
+// The ObserverVec must have zero, one, or two labels. The only allowed label
+// names are "code" and "method". The function panics if any other instance
+// labels are provided. The Observe method of the Observer in the ObserverVec
+// is called with the response size in bytes. Partitioning happens by HTTP
+// status code and/or HTTP method if the respective instance label names are
+// present in the ObserverVec. For unpartitioned observations, use an
+// ObserverVec with zero labels. Note that partitioning of Histograms is
+// expensive and should be used judiciously.
+//
+// If the wrapped Handler does not set a status code, a status code of 200 is assumed.
+//
+// If the wrapped Handler panics, no values are reported.
+//
+// See the example for InstrumentHandlerDuration for example usage.
+func InstrumentHandlerResponseSize(obs prometheus.ObserverVec, next http.Handler) http.Handler {
+	code, method := checkLabels(obs)
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		d := newDelegator(w, nil)
+		next.ServeHTTP(d, r)
+		obs.With(labels(code, method, r.Method, d.Status())).Observe(float64(d.Written()))
+	})
+}
+
+func checkLabels(c prometheus.Collector) (code bool, method bool) {
+	// TODO(beorn7): Remove this hacky way to check for instance labels
+	// once Descriptors can have their dimensionality queried.
+	var (
+		desc *prometheus.Desc
+		pm   dto.Metric
+	)
+
+	descc := make(chan *prometheus.Desc, 1)
+	c.Describe(descc)
+
+	select {
+	case desc = <-descc:
+	default:
+		panic("no description provided by collector")
+	}
+	select {
+	case <-descc:
+		panic("more than one description provided by collector")
+	default:
+	}
+
+	close(descc)
+
+	if _, err := prometheus.NewConstMetric(desc, prometheus.UntypedValue, 0); err == nil {
+		return
+	}
+	if m, err := prometheus.NewConstMetric(desc, prometheus.UntypedValue, 0, magicString); err == nil {
+		if err := m.Write(&pm); err != nil {
+			panic("error checking metric for labels")
+		}
+		for _, label := range pm.Label {
+			name, value := label.GetName(), label.GetValue()
+			if value != magicString {
+				continue
+			}
+			switch name {
+			case "code":
+				code = true
+			case "method":
+				method = true
+			default:
+				panic("metric partitioned with non-supported labels")
+			}
+			return
+		}
+		panic("previously set label not found – this must never happen")
+	}
+	if m, err := prometheus.NewConstMetric(desc, prometheus.UntypedValue, 0, magicString, magicString); err == nil {
+		if err := m.Write(&pm); err != nil {
+			panic("error checking metric for labels")
+		}
+		for _, label := range pm.Label {
+			name, value := label.GetName(), label.GetValue()
+			if value != magicString {
+				continue
+			}
+			if name == "code" || name == "method" {
+				continue
+			}
+			panic("metric partitioned with non-supported labels")
+		}
+		code = true
+		method = true
+		return
+	}
+	panic("metric partitioned with non-supported labels")
+}
+
+// emptyLabels is a one-time allocation for non-partitioned metrics to avoid
+// unnecessary allocations on each request.
+var emptyLabels = prometheus.Labels{}
+
+func labels(code, method bool, reqMethod string, status int) prometheus.Labels {
+	if !(code || method) {
+		return emptyLabels
+	}
+	labels := prometheus.Labels{}
+
+	if code {
+		labels["code"] = sanitizeCode(status)
+	}
+	if method {
+		labels["method"] = sanitizeMethod(reqMethod)
+	}
+
+	return labels
+}
+
+func computeApproximateRequestSize(r *http.Request) int {
+	s := 0
+	if r.URL != nil {
+		s += len(r.URL.String())
+	}
+
+	s += len(r.Method)
+	s += len(r.Proto)
+	for name, values := range r.Header {
+		s += len(name)
+		for _, value := range values {
+			s += len(value)
+		}
+	}
+	s += len(r.Host)
+
+	// N.B. r.Form and r.MultipartForm are assumed to be included in r.URL.
+
+	if r.ContentLength != -1 {
+		s += int(r.ContentLength)
+	}
+	return s
+}
+
+func sanitizeMethod(m string) string {
+	switch m {
+	case "GET", "get":
+		return "get"
+	case "PUT", "put":
+		return "put"
+	case "HEAD", "head":
+		return "head"
+	case "POST", "post":
+		return "post"
+	case "DELETE", "delete":
+		return "delete"
+	case "CONNECT", "connect":
+		return "connect"
+	case "OPTIONS", "options":
+		return "options"
+	case "NOTIFY", "notify":
+		return "notify"
+	default:
+		return strings.ToLower(m)
+	}
+}
+
+// If the wrapped http.Handler has not set a status code, i.e. the value is
+// currently 0, santizeCode will return 200, for consistency with behavior in
+// the stdlib.
+func sanitizeCode(s int) string {
+	switch s {
+	case 100:
+		return "100"
+	case 101:
+		return "101"
+
+	case 200, 0:
+		return "200"
+	case 201:
+		return "201"
+	case 202:
+		return "202"
+	case 203:
+		return "203"
+	case 204:
+		return "204"
+	case 205:
+		return "205"
+	case 206:
+		return "206"
+
+	case 300:
+		return "300"
+	case 301:
+		return "301"
+	case 302:
+		return "302"
+	case 304:
+		return "304"
+	case 305:
+		return "305"
+	case 307:
+		return "307"
+
+	case 400:
+		return "400"
+	case 401:
+		return "401"
+	case 402:
+		return "402"
+	case 403:
+		return "403"
+	case 404:
+		return "404"
+	case 405:
+		return "405"
+	case 406:
+		return "406"
+	case 407:
+		return "407"
+	case 408:
+		return "408"
+	case 409:
+		return "409"
+	case 410:
+		return "410"
+	case 411:
+		return "411"
+	case 412:
+		return "412"
+	case 413:
+		return "413"
+	case 414:
+		return "414"
+	case 415:
+		return "415"
+	case 416:
+		return "416"
+	case 417:
+		return "417"
+	case 418:
+		return "418"
+
+	case 500:
+		return "500"
+	case 501:
+		return "501"
+	case 502:
+		return "502"
+	case 503:
+		return "503"
+	case 504:
+		return "504"
+	case 505:
+		return "505"
+
+	case 428:
+		return "428"
+	case 429:
+		return "429"
+	case 431:
+		return "431"
+	case 511:
+		return "511"
+
+	default:
+		return strconv.Itoa(s)
+	}
+}

vendor/github.com/prometheus/client_golang/prometheus/promhttp/instrument_server_test.go

@@ -0,0 +1,233 @@
+// Copyright 2017 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package promhttp
+
+import (
+	"io"
+	"log"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+func TestMiddlewareAPI(t *testing.T) {
+	reg := prometheus.NewRegistry()
+
+	inFlightGauge := prometheus.NewGauge(prometheus.GaugeOpts{
+		Name: "in_flight_requests",
+		Help: "A gauge of requests currently being served by the wrapped handler.",
+	})
+
+	counter := prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "api_requests_total",
+			Help: "A counter for requests to the wrapped handler.",
+		},
+		[]string{"code", "method"},
+	)
+
+	histVec := prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name:        "response_duration_seconds",
+			Help:        "A histogram of request latencies.",
+			Buckets:     prometheus.DefBuckets,
+			ConstLabels: prometheus.Labels{"handler": "api"},
+		},
+		[]string{"method"},
+	)
+
+	writeHeaderVec := prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name:        "write_header_duration_seconds",
+			Help:        "A histogram of time to first write latencies.",
+			Buckets:     prometheus.DefBuckets,
+			ConstLabels: prometheus.Labels{"handler": "api"},
+		},
+		[]string{},
+	)
+
+	responseSize := prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name:    "push_request_size_bytes",
+			Help:    "A histogram of request sizes for requests.",
+			Buckets: []float64{200, 500, 900, 1500},
+		},
+		[]string{},
+	)
+
+	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte("OK"))
+	})
+
+	reg.MustRegister(inFlightGauge, counter, histVec, responseSize, writeHeaderVec)
+
+	chain := InstrumentHandlerInFlight(inFlightGauge,
+		InstrumentHandlerCounter(counter,
+			InstrumentHandlerDuration(histVec,
+				InstrumentHandlerTimeToWriteHeader(writeHeaderVec,
+					InstrumentHandlerResponseSize(responseSize, handler),
+				),
+			),
+		),
+	)
+
+	r, _ := http.NewRequest("GET", "www.example.com", nil)
+	w := httptest.NewRecorder()
+	chain.ServeHTTP(w, r)
+}
+
+func TestInstrumentTimeToFirstWrite(t *testing.T) {
+	var i int
+	dobs := &responseWriterDelegator{
+		ResponseWriter: httptest.NewRecorder(),
+		observeWriteHeader: func(status int) {
+			i = status
+		},
+	}
+	d := newDelegator(dobs, nil)
+
+	d.WriteHeader(http.StatusOK)
+
+	if i != http.StatusOK {
+		t.Fatalf("failed to execute observeWriteHeader")
+	}
+}
+
+// testResponseWriter is an http.ResponseWriter that also implements
+// http.CloseNotifier, http.Flusher, and io.ReaderFrom.
+type testResponseWriter struct {
+	closeNotifyCalled, flushCalled, readFromCalled bool
+}
+
+func (t *testResponseWriter) Header() http.Header       { return nil }
+func (t *testResponseWriter) Write([]byte) (int, error) { return 0, nil }
+func (t *testResponseWriter) WriteHeader(int)           {}
+func (t *testResponseWriter) CloseNotify() <-chan bool {
+	t.closeNotifyCalled = true
+	return nil
+}
+func (t *testResponseWriter) Flush() { t.flushCalled = true }
+func (t *testResponseWriter) ReadFrom(io.Reader) (int64, error) {
+	t.readFromCalled = true
+	return 0, nil
+}
+
+func TestInterfaceUpgrade(t *testing.T) {
+	w := &testResponseWriter{}
+	d := newDelegator(w, nil)
+	d.(http.CloseNotifier).CloseNotify()
+	if !w.closeNotifyCalled {
+		t.Error("CloseNotify not called")
+	}
+	d.(http.Flusher).Flush()
+	if !w.flushCalled {
+		t.Error("Flush not called")
+	}
+	d.(io.ReaderFrom).ReadFrom(nil)
+	if !w.readFromCalled {
+		t.Error("ReadFrom not called")
+	}
+	if _, ok := d.(http.Hijacker); ok {
+		t.Error("delegator unexpectedly implements http.Hijacker")
+	}
+}
+
+func ExampleInstrumentHandlerDuration() {
+	inFlightGauge := prometheus.NewGauge(prometheus.GaugeOpts{
+		Name: "in_flight_requests",
+		Help: "A gauge of requests currently being served by the wrapped handler.",
+	})
+
+	counter := prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "api_requests_total",
+			Help: "A counter for requests to the wrapped handler.",
+		},
+		[]string{"code", "method"},
+	)
+
+	// pushVec and pullVec are partitioned by the HTTP method and use custom
+	// buckets based on the expected request duration. ConstLabels are used
+	// to set a handler label to mark pushVec as tracking the durations for
+	// pushes and pullVec as tracking the durations for pulls. Note that
+	// Name, Help, and Buckets need to be the same for consistency, so we
+	// use the same HistogramOpts after just modifying the ConstLabels.
+	histogramOpts := prometheus.HistogramOpts{
+		Name:        "request_duration_seconds",
+		Help:        "A histogram of latencies for requests.",
+		Buckets:     []float64{.25, .5, 1, 2.5, 5, 10},
+		ConstLabels: prometheus.Labels{"handler": "push"},
+	}
+	pushVec := prometheus.NewHistogramVec(
+		histogramOpts,
+		[]string{"method"},
+	)
+	histogramOpts.ConstLabels = prometheus.Labels{"handler": "pull"}
+	pullVec := prometheus.NewHistogramVec(
+		histogramOpts,
+		[]string{"method"},
+	)
+
+	// responseSize has no labels, making it a zero-dimensional
+	// ObserverVec.
+	responseSize := prometheus.NewHistogramVec(
+		prometheus.HistogramOpts{
+			Name:    "response_size_bytes",
+			Help:    "A histogram of response sizes for requests.",
+			Buckets: []float64{200, 500, 900, 1500},
+		},
+		[]string{},
+	)
+
+	// Create the handlers that will be wrapped by the middleware.
+	pushHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte("Push"))
+	})
+	pullHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte("Pull"))
+	})
+
+	// Register all of the metrics in the standard registry.
+	prometheus.MustRegister(inFlightGauge, counter, pullVec, pushVec, responseSize)
+
+	// Wrap the pushHandler with our shared middleware, but use the
+	// endpoint-specific pushVec with InstrumentHandlerDuration.
+	pushChain := InstrumentHandlerInFlight(inFlightGauge,
+		InstrumentHandlerCounter(counter,
+			InstrumentHandlerDuration(pushVec,
+				InstrumentHandlerResponseSize(responseSize, pushHandler),
+			),
+		),
+	)
+
+	// Wrap the pushHandler with the shared middleware, but use the
+	// endpoint-specific pullVec with InstrumentHandlerDuration.
+	pullChain := InstrumentHandlerInFlight(inFlightGauge,
+		InstrumentHandlerCounter(counter,
+			InstrumentHandlerDuration(pullVec,
+				InstrumentHandlerResponseSize(responseSize, pullHandler),
+			),
+		),
+	)
+
+	http.Handle("/metrics", Handler())
+	http.Handle("/push", pushChain)
+	http.Handle("/pull", pullChain)
+
+	if err := http.ListenAndServe(":3000", nil); err != nil {
+		log.Fatal(err)
+	}
+}

vendor/github.com/prometheus/client_golang/prometheus/push/example_add_from_gatherer_test.go

@@ -0,0 +1,84 @@
+// Copyright 2016 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Copyright (c) 2013, The Prometheus Authors
+// All rights reserved.
+//
+// Use of this source code is governed by a BSD-style license that can be found
+// in the LICENSE file.
+
+package push_test
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/push"
+)
+
+var (
+	completionTime = prometheus.NewGauge(prometheus.GaugeOpts{
+		Name: "db_backup_last_completion_timestamp_seconds",
+		Help: "The timestamp of the last completion of a DB backup, successful or not.",
+	})
+	successTime = prometheus.NewGauge(prometheus.GaugeOpts{
+		Name: "db_backup_last_success_timestamp_seconds",
+		Help: "The timestamp of the last successful completion of a DB backup.",
+	})
+	duration = prometheus.NewGauge(prometheus.GaugeOpts{
+		Name: "db_backup_duration_seconds",
+		Help: "The duration of the last DB backup in seconds.",
+	})
+	records = prometheus.NewGauge(prometheus.GaugeOpts{
+		Name: "db_backup_records_processed",
+		Help: "The number of records processed in the last DB backup.",
+	})
+)
+
+func performBackup() (int, error) {
+	// Perform the backup and return the number of backed up records and any
+	// applicable error.
+	// ...
+	return 42, nil
+}
+
+func ExampleAddFromGatherer() {
+	registry := prometheus.NewRegistry()
+	registry.MustRegister(completionTime, duration, records)
+	// Note that successTime is not registered at this time.
+
+	start := time.Now()
+	n, err := performBackup()
+	records.Set(float64(n))
+	// Note that time.Since only uses a monotonic clock in Go1.9+.
+	duration.Set(time.Since(start).Seconds())
+	completionTime.SetToCurrentTime()
+	if err != nil {
+		fmt.Println("DB backup failed:", err)
+	} else {
+		// Only now register successTime.
+		registry.MustRegister(successTime)
+		successTime.SetToCurrentTime()
+	}
+	// AddFromGatherer is used here rather than FromGatherer to not delete a
+	// previously pushed success timestamp in case of a failure of this
+	// backup.
+	if err := push.AddFromGatherer(
+		"db_backup", nil,
+		"http://pushgateway:9091",
+		registry,
+	); err != nil {
+		fmt.Println("Could not push to Pushgateway:", err)
+	}
+}

vendor/github.com/prometheus/client_golang/prometheus/push/examples_test.go

@@ -0,0 +1,36 @@
+// Copyright 2016 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package push_test
+
+import (
+	"fmt"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/push"
+)
+
+func ExampleCollectors() {
+	completionTime := prometheus.NewGauge(prometheus.GaugeOpts{
+		Name: "db_backup_last_completion_timestamp_seconds",
+		Help: "The timestamp of the last successful completion of a DB backup.",
+	})
+	completionTime.SetToCurrentTime()
+	if err := push.Collectors(
+		"db_backup", push.HostnameGroupingKey(),
+		"http://pushgateway:9091",
+		completionTime,
+	); err != nil {
+		fmt.Println("Could not push completion time to Pushgateway:", err)
+	}
+}

vendor/github.com/prometheus/client_golang/prometheus/push/push.go

@@ -0,0 +1,172 @@
+// Copyright 2015 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Copyright (c) 2013, The Prometheus Authors
+// All rights reserved.
+//
+// Use of this source code is governed by a BSD-style license that can be found
+// in the LICENSE file.
+
+// Package push provides functions to push metrics to a Pushgateway. The metrics
+// to push are either collected from a provided registry, or from explicitly
+// listed collectors.
+//
+// See the documentation of the Pushgateway to understand the meaning of the
+// grouping parameters and the differences between push.Registry and
+// push.Collectors on the one hand and push.AddRegistry and push.AddCollectors
+// on the other hand: https://github.com/prometheus/pushgateway
+package push
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"os"
+	"strings"
+
+	"github.com/prometheus/common/expfmt"
+	"github.com/prometheus/common/model"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const contentTypeHeader = "Content-Type"
+
+// FromGatherer triggers a metric collection by the provided Gatherer (which is
+// usually implemented by a prometheus.Registry) and pushes all gathered metrics
+// to the Pushgateway specified by url, using the provided job name and the
+// (optional) further grouping labels (the grouping map may be nil). See the
+// Pushgateway documentation for detailed implications of the job and other
+// grouping labels. Neither the job name nor any grouping label value may
+// contain a "/". The metrics pushed must not contain a job label of their own
+// nor any of the grouping labels.
+//
+// You can use just host:port or ip:port as url, in which case 'http://' is
+// added automatically. You can also include the schema in the URL. However, do
+// not include the '/metrics/jobs/...' part.
+//
+// Note that all previously pushed metrics with the same job and other grouping
+// labels will be replaced with the metrics pushed by this call. (It uses HTTP
+// method 'PUT' to push to the Pushgateway.)
+func FromGatherer(job string, grouping map[string]string, url string, g prometheus.Gatherer) error {
+	return push(job, grouping, url, g, "PUT")
+}
+
+// AddFromGatherer works like FromGatherer, but only previously pushed metrics
+// with the same name (and the same job and other grouping labels) will be
+// replaced. (It uses HTTP method 'POST' to push to the Pushgateway.)
+func AddFromGatherer(job string, grouping map[string]string, url string, g prometheus.Gatherer) error {
+	return push(job, grouping, url, g, "POST")
+}
+
+func push(job string, grouping map[string]string, pushURL string, g prometheus.Gatherer, method string) error {
+	if !strings.Contains(pushURL, "://") {
+		pushURL = "http://" + pushURL
+	}
+	if strings.HasSuffix(pushURL, "/") {
+		pushURL = pushURL[:len(pushURL)-1]
+	}
+
+	if strings.Contains(job, "/") {
+		return fmt.Errorf("job contains '/': %s", job)
+	}
+	urlComponents := []string{url.QueryEscape(job)}
+	for ln, lv := range grouping {
+		if !model.LabelName(ln).IsValid() {
+			return fmt.Errorf("grouping label has invalid name: %s", ln)
+		}
+		if strings.Contains(lv, "/") {
+			return fmt.Errorf("value of grouping label %s contains '/': %s", ln, lv)
+		}
+		urlComponents = append(urlComponents, ln, lv)
+	}
+	pushURL = fmt.Sprintf("%s/metrics/job/%s", pushURL, strings.Join(urlComponents, "/"))
+
+	mfs, err := g.Gather()
+	if err != nil {
+		return err
+	}
+	buf := &bytes.Buffer{}
+	enc := expfmt.NewEncoder(buf, expfmt.FmtProtoDelim)
+	// Check for pre-existing grouping labels:
+	for _, mf := range mfs {
+		for _, m := range mf.GetMetric() {
+			for _, l := range m.GetLabel() {
+				if l.GetName() == "job" {
+					return fmt.Errorf("pushed metric %s (%s) already contains a job label", mf.GetName(), m)
+				}
+				if _, ok := grouping[l.GetName()]; ok {
+					return fmt.Errorf(
+						"pushed metric %s (%s) already contains grouping label %s",
+						mf.GetName(), m, l.GetName(),
+					)
+				}
+			}
+		}
+		enc.Encode(mf)
+	}
+	req, err := http.NewRequest(method, pushURL, buf)
+	if err != nil {
+		return err
+	}
+	req.Header.Set(contentTypeHeader, string(expfmt.FmtProtoDelim))
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != 202 {
+		body, _ := ioutil.ReadAll(resp.Body) // Ignore any further error as this is for an error message only.
+		return fmt.Errorf("unexpected status code %d while pushing to %s: %s", resp.StatusCode, pushURL, body)
+	}
+	return nil
+}
+
+// Collectors works like FromGatherer, but it does not use a Gatherer. Instead,
+// it collects from the provided collectors directly. It is a convenient way to
+// push only a few metrics.
+func Collectors(job string, grouping map[string]string, url string, collectors ...prometheus.Collector) error {
+	return pushCollectors(job, grouping, url, "PUT", collectors...)
+}
+
+// AddCollectors works like AddFromGatherer, but it does not use a Gatherer.
+// Instead, it collects from the provided collectors directly. It is a
+// convenient way to push only a few metrics.
+func AddCollectors(job string, grouping map[string]string, url string, collectors ...prometheus.Collector) error {
+	return pushCollectors(job, grouping, url, "POST", collectors...)
+}
+
+func pushCollectors(job string, grouping map[string]string, url, method string, collectors ...prometheus.Collector) error {
+	r := prometheus.NewRegistry()
+	for _, collector := range collectors {
+		if err := r.Register(collector); err != nil {
+			return err
+		}
+	}
+	return push(job, grouping, url, r, method)
+}
+
+// HostnameGroupingKey returns a label map with the only entry
+// {instance="<hostname>"}. This can be conveniently used as the grouping
+// parameter if metrics should be pushed with the hostname as label. The
+// returned map is created upon each call so that the caller is free to add more
+// labels to the map.
+func HostnameGroupingKey() map[string]string {
+	hostname, err := os.Hostname()
+	if err != nil {
+		return map[string]string{"instance": "unknown"}
+	}
+	return map[string]string{"instance": hostname}
+}

vendor/github.com/prometheus/client_golang/prometheus/push/push_test.go

@@ -0,0 +1,176 @@
+// Copyright 2016 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Copyright (c) 2013, The Prometheus Authors
+// All rights reserved.
+//
+// Use of this source code is governed by a BSD-style license that can be found
+// in the LICENSE file.
+
+package push
+
+import (
+	"bytes"
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"testing"
+
+	"github.com/prometheus/common/expfmt"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+func TestPush(t *testing.T) {
+
+	var (
+		lastMethod string
+		lastBody   []byte
+		lastPath   string
+	)
+
+	host, err := os.Hostname()
+	if err != nil {
+		t.Error(err)
+	}
+
+	// Fake a Pushgateway that always responds with 202.
+	pgwOK := httptest.NewServer(
+		http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			lastMethod = r.Method
+			var err error
+			lastBody, err = ioutil.ReadAll(r.Body)
+			if err != nil {
+				t.Fatal(err)
+			}
+			lastPath = r.URL.EscapedPath()
+			w.Header().Set("Content-Type", `text/plain; charset=utf-8`)
+			w.WriteHeader(http.StatusAccepted)
+		}),
+	)
+	defer pgwOK.Close()
+
+	// Fake a Pushgateway that always responds with 500.
+	pgwErr := httptest.NewServer(
+		http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			http.Error(w, "fake error", http.StatusInternalServerError)
+		}),
+	)
+	defer pgwErr.Close()
+
+	metric1 := prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "testname1",
+		Help: "testhelp1",
+	})
+	metric2 := prometheus.NewGauge(prometheus.GaugeOpts{
+		Name:        "testname2",
+		Help:        "testhelp2",
+		ConstLabels: prometheus.Labels{"foo": "bar", "dings": "bums"},
+	})
+
+	reg := prometheus.NewRegistry()
+	reg.MustRegister(metric1)
+	reg.MustRegister(metric2)
+
+	mfs, err := reg.Gather()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	buf := &bytes.Buffer{}
+	enc := expfmt.NewEncoder(buf, expfmt.FmtProtoDelim)
+
+	for _, mf := range mfs {
+		if err := enc.Encode(mf); err != nil {
+			t.Fatal(err)
+		}
+	}
+	wantBody := buf.Bytes()
+
+	// PushCollectors, all good.
+	if err := Collectors("testjob", HostnameGroupingKey(), pgwOK.URL, metric1, metric2); err != nil {
+		t.Fatal(err)
+	}
+	if lastMethod != "PUT" {
+		t.Error("want method PUT for PushCollectors, got", lastMethod)
+	}
+	if bytes.Compare(lastBody, wantBody) != 0 {
+		t.Errorf("got body %v, want %v", lastBody, wantBody)
+	}
+	if lastPath != "/metrics/job/testjob/instance/"+host {
+		t.Error("unexpected path:", lastPath)
+	}
+
+	// PushAddCollectors, with nil grouping, all good.
+	if err := AddCollectors("testjob", nil, pgwOK.URL, metric1, metric2); err != nil {
+		t.Fatal(err)
+	}
+	if lastMethod != "POST" {
+		t.Error("want method POST for PushAddCollectors, got", lastMethod)
+	}
+	if bytes.Compare(lastBody, wantBody) != 0 {
+		t.Errorf("got body %v, want %v", lastBody, wantBody)
+	}
+	if lastPath != "/metrics/job/testjob" {
+		t.Error("unexpected path:", lastPath)
+	}
+
+	// PushCollectors with a broken PGW.
+	if err := Collectors("testjob", nil, pgwErr.URL, metric1, metric2); err == nil {
+		t.Error("push to broken Pushgateway succeeded")
+	} else {
+		if got, want := err.Error(), "unexpected status code 500 while pushing to "+pgwErr.URL+"/metrics/job/testjob: fake error\n"; got != want {
+			t.Errorf("got error %q, want %q", got, want)
+		}
+	}
+
+	// PushCollectors with invalid grouping or job.
+	if err := Collectors("testjob", map[string]string{"foo": "bums"}, pgwErr.URL, metric1, metric2); err == nil {
+		t.Error("push with grouping contained in metrics succeeded")
+	}
+	if err := Collectors("test/job", nil, pgwErr.URL, metric1, metric2); err == nil {
+		t.Error("push with invalid job value succeeded")
+	}
+	if err := Collectors("testjob", map[string]string{"foo/bar": "bums"}, pgwErr.URL, metric1, metric2); err == nil {
+		t.Error("push with invalid grouping succeeded")
+	}
+	if err := Collectors("testjob", map[string]string{"foo-bar": "bums"}, pgwErr.URL, metric1, metric2); err == nil {
+		t.Error("push with invalid grouping succeeded")
+	}
+
+	// Push registry, all good.
+	if err := FromGatherer("testjob", HostnameGroupingKey(), pgwOK.URL, reg); err != nil {
+		t.Fatal(err)
+	}
+	if lastMethod != "PUT" {
+		t.Error("want method PUT for Push, got", lastMethod)
+	}
+	if bytes.Compare(lastBody, wantBody) != 0 {
+		t.Errorf("got body %v, want %v", lastBody, wantBody)
+	}
+
+	// PushAdd registry, all good.
+	if err := AddFromGatherer("testjob", map[string]string{"a": "x", "b": "y"}, pgwOK.URL, reg); err != nil {
+		t.Fatal(err)
+	}
+	if lastMethod != "POST" {
+		t.Error("want method POSTT for PushAdd, got", lastMethod)
+	}
+	if bytes.Compare(lastBody, wantBody) != 0 {
+		t.Errorf("got body %v, want %v", lastBody, wantBody)
+	}
+	if lastPath != "/metrics/job/testjob/a/x/b/y" && lastPath != "/metrics/job/testjob/b/y/a/x" {
+		t.Error("unexpected path:", lastPath)
+	}
+}

vendor/github.com/prometheus/client_golang/prometheus/registry.go

@@ -0,0 +1,762 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"os"
+	"sort"
+	"sync"
+	"unicode/utf8"
+
+	"github.com/golang/protobuf/proto"
+
+	dto "github.com/prometheus/client_model/go"
+)
+
+const (
+	// Capacity for the channel to collect metrics and descriptors.
+	capMetricChan = 1000
+	capDescChan   = 10
+)
+
+// DefaultRegisterer and DefaultGatherer are the implementations of the
+// Registerer and Gatherer interface a number of convenience functions in this
+// package act on. Initially, both variables point to the same Registry, which
+// has a process collector (see NewProcessCollector) and a Go collector (see
+// NewGoCollector) already registered. This approach to keep default instances
+// as global state mirrors the approach of other packages in the Go standard
+// library. Note that there are caveats. Change the variables with caution and
+// only if you understand the consequences. Users who want to avoid global state
+// altogether should not use the convenience function and act on custom
+// instances instead.
+var (
+	defaultRegistry              = NewRegistry()
+	DefaultRegisterer Registerer = defaultRegistry
+	DefaultGatherer   Gatherer   = defaultRegistry
+)
+
+func init() {
+	MustRegister(NewProcessCollector(os.Getpid(), ""))
+	MustRegister(NewGoCollector())
+}
+
+// NewRegistry creates a new vanilla Registry without any Collectors
+// pre-registered.
+func NewRegistry() *Registry {
+	return &Registry{
+		collectorsByID:  map[uint64]Collector{},
+		descIDs:         map[uint64]struct{}{},
+		dimHashesByName: map[string]uint64{},
+	}
+}
+
+// NewPedanticRegistry returns a registry that checks during collection if each
+// collected Metric is consistent with its reported Desc, and if the Desc has
+// actually been registered with the registry.
+//
+// Usually, a Registry will be happy as long as the union of all collected
+// Metrics is consistent and valid even if some metrics are not consistent with
+// their own Desc or a Desc provided by their registered Collector. Well-behaved
+// Collectors and Metrics will only provide consistent Descs. This Registry is
+// useful to test the implementation of Collectors and Metrics.
+func NewPedanticRegistry() *Registry {
+	r := NewRegistry()
+	r.pedanticChecksEnabled = true
+	return r
+}
+
+// Registerer is the interface for the part of a registry in charge of
+// registering and unregistering. Users of custom registries should use
+// Registerer as type for registration purposes (rather than the Registry type
+// directly). In that way, they are free to use custom Registerer implementation
+// (e.g. for testing purposes).
+type Registerer interface {
+	// Register registers a new Collector to be included in metrics
+	// collection. It returns an error if the descriptors provided by the
+	// Collector are invalid or if they — in combination with descriptors of
+	// already registered Collectors — do not fulfill the consistency and
+	// uniqueness criteria described in the documentation of metric.Desc.
+	//
+	// If the provided Collector is equal to a Collector already registered
+	// (which includes the case of re-registering the same Collector), the
+	// returned error is an instance of AlreadyRegisteredError, which
+	// contains the previously registered Collector.
+	//
+	// It is in general not safe to register the same Collector multiple
+	// times concurrently.
+	Register(Collector) error
+	// MustRegister works like Register but registers any number of
+	// Collectors and panics upon the first registration that causes an
+	// error.
+	MustRegister(...Collector)
+	// Unregister unregisters the Collector that equals the Collector passed
+	// in as an argument.  (Two Collectors are considered equal if their
+	// Describe method yields the same set of descriptors.) The function
+	// returns whether a Collector was unregistered.
+	//
+	// Note that even after unregistering, it will not be possible to
+	// register a new Collector that is inconsistent with the unregistered
+	// Collector, e.g. a Collector collecting metrics with the same name but
+	// a different help string. The rationale here is that the same registry
+	// instance must only collect consistent metrics throughout its
+	// lifetime.
+	Unregister(Collector) bool
+}
+
+// Gatherer is the interface for the part of a registry in charge of gathering
+// the collected metrics into a number of MetricFamilies. The Gatherer interface
+// comes with the same general implication as described for the Registerer
+// interface.
+type Gatherer interface {
+	// Gather calls the Collect method of the registered Collectors and then
+	// gathers the collected metrics into a lexicographically sorted slice
+	// of MetricFamily protobufs. Even if an error occurs, Gather attempts
+	// to gather as many metrics as possible. Hence, if a non-nil error is
+	// returned, the returned MetricFamily slice could be nil (in case of a
+	// fatal error that prevented any meaningful metric collection) or
+	// contain a number of MetricFamily protobufs, some of which might be
+	// incomplete, and some might be missing altogether. The returned error
+	// (which might be a MultiError) explains the details. In scenarios
+	// where complete collection is critical, the returned MetricFamily
+	// protobufs should be disregarded if the returned error is non-nil.
+	Gather() ([]*dto.MetricFamily, error)
+}
+
+// Register registers the provided Collector with the DefaultRegisterer.
+//
+// Register is a shortcut for DefaultRegisterer.Register(c). See there for more
+// details.
+func Register(c Collector) error {
+	return DefaultRegisterer.Register(c)
+}
+
+// MustRegister registers the provided Collectors with the DefaultRegisterer and
+// panics if any error occurs.
+//
+// MustRegister is a shortcut for DefaultRegisterer.MustRegister(cs...). See
+// there for more details.
+func MustRegister(cs ...Collector) {
+	DefaultRegisterer.MustRegister(cs...)
+}
+
+// Unregister removes the registration of the provided Collector from the
+// DefaultRegisterer.
+//
+// Unregister is a shortcut for DefaultRegisterer.Unregister(c). See there for
+// more details.
+func Unregister(c Collector) bool {
+	return DefaultRegisterer.Unregister(c)
+}
+
+// GathererFunc turns a function into a Gatherer.
+type GathererFunc func() ([]*dto.MetricFamily, error)
+
+// Gather implements Gatherer.
+func (gf GathererFunc) Gather() ([]*dto.MetricFamily, error) {
+	return gf()
+}
+
+// AlreadyRegisteredError is returned by the Register method if the Collector to
+// be registered has already been registered before, or a different Collector
+// that collects the same metrics has been registered before. Registration fails
+// in that case, but you can detect from the kind of error what has
+// happened. The error contains fields for the existing Collector and the
+// (rejected) new Collector that equals the existing one. This can be used to
+// find out if an equal Collector has been registered before and switch over to
+// using the old one, as demonstrated in the example.
+type AlreadyRegisteredError struct {
+	ExistingCollector, NewCollector Collector
+}
+
+func (err AlreadyRegisteredError) Error() string {
+	return "duplicate metrics collector registration attempted"
+}
+
+// MultiError is a slice of errors implementing the error interface. It is used
+// by a Gatherer to report multiple errors during MetricFamily gathering.
+type MultiError []error
+
+func (errs MultiError) Error() string {
+	if len(errs) == 0 {
+		return ""
+	}
+	buf := &bytes.Buffer{}
+	fmt.Fprintf(buf, "%d error(s) occurred:", len(errs))
+	for _, err := range errs {
+		fmt.Fprintf(buf, "\n* %s", err)
+	}
+	return buf.String()
+}
+
+// MaybeUnwrap returns nil if len(errs) is 0. It returns the first and only
+// contained error as error if len(errs is 1). In all other cases, it returns
+// the MultiError directly. This is helpful for returning a MultiError in a way
+// that only uses the MultiError if needed.
+func (errs MultiError) MaybeUnwrap() error {
+	switch len(errs) {
+	case 0:
+		return nil
+	case 1:
+		return errs[0]
+	default:
+		return errs
+	}
+}
+
+// Registry registers Prometheus collectors, collects their metrics, and gathers
+// them into MetricFamilies for exposition. It implements both Registerer and
+// Gatherer. The zero value is not usable. Create instances with NewRegistry or
+// NewPedanticRegistry.
+type Registry struct {
+	mtx                   sync.RWMutex
+	collectorsByID        map[uint64]Collector // ID is a hash of the descIDs.
+	descIDs               map[uint64]struct{}
+	dimHashesByName       map[string]uint64
+	pedanticChecksEnabled bool
+}
+
+// Register implements Registerer.
+func (r *Registry) Register(c Collector) error {
+	var (
+		descChan           = make(chan *Desc, capDescChan)
+		newDescIDs         = map[uint64]struct{}{}
+		newDimHashesByName = map[string]uint64{}
+		collectorID        uint64 // Just a sum of all desc IDs.
+		duplicateDescErr   error
+	)
+	go func() {
+		c.Describe(descChan)
+		close(descChan)
+	}()
+	r.mtx.Lock()
+	defer r.mtx.Unlock()
+	// Conduct various tests...
+	for desc := range descChan {
+
+		// Is the descriptor valid at all?
+		if desc.err != nil {
+			return fmt.Errorf("descriptor %s is invalid: %s", desc, desc.err)
+		}
+
+		// Is the descID unique?
+		// (In other words: Is the fqName + constLabel combination unique?)
+		if _, exists := r.descIDs[desc.id]; exists {
+			duplicateDescErr = fmt.Errorf("descriptor %s already exists with the same fully-qualified name and const label values", desc)
+		}
+		// If it is not a duplicate desc in this collector, add it to
+		// the collectorID.  (We allow duplicate descs within the same
+		// collector, but their existence must be a no-op.)
+		if _, exists := newDescIDs[desc.id]; !exists {
+			newDescIDs[desc.id] = struct{}{}
+			collectorID += desc.id
+		}
+
+		// Are all the label names and the help string consistent with
+		// previous descriptors of the same name?
+		// First check existing descriptors...
+		if dimHash, exists := r.dimHashesByName[desc.fqName]; exists {
+			if dimHash != desc.dimHash {
+				return fmt.Errorf("a previously registered descriptor with the same fully-qualified name as %s has different label names or a different help string", desc)
+			}
+		} else {
+			// ...then check the new descriptors already seen.
+			if dimHash, exists := newDimHashesByName[desc.fqName]; exists {
+				if dimHash != desc.dimHash {
+					return fmt.Errorf("descriptors reported by collector have inconsistent label names or help strings for the same fully-qualified name, offender is %s", desc)
+				}
+			} else {
+				newDimHashesByName[desc.fqName] = desc.dimHash
+			}
+		}
+	}
+	// Did anything happen at all?
+	if len(newDescIDs) == 0 {
+		return errors.New("collector has no descriptors")
+	}
+	if existing, exists := r.collectorsByID[collectorID]; exists {
+		return AlreadyRegisteredError{
+			ExistingCollector: existing,
+			NewCollector:      c,
+		}
+	}
+	// If the collectorID is new, but at least one of the descs existed
+	// before, we are in trouble.
+	if duplicateDescErr != nil {
+		return duplicateDescErr
+	}
+
+	// Only after all tests have passed, actually register.
+	r.collectorsByID[collectorID] = c
+	for hash := range newDescIDs {
+		r.descIDs[hash] = struct{}{}
+	}
+	for name, dimHash := range newDimHashesByName {
+		r.dimHashesByName[name] = dimHash
+	}
+	return nil
+}
+
+// Unregister implements Registerer.
+func (r *Registry) Unregister(c Collector) bool {
+	var (
+		descChan    = make(chan *Desc, capDescChan)
+		descIDs     = map[uint64]struct{}{}
+		collectorID uint64 // Just a sum of the desc IDs.
+	)
+	go func() {
+		c.Describe(descChan)
+		close(descChan)
+	}()
+	for desc := range descChan {
+		if _, exists := descIDs[desc.id]; !exists {
+			collectorID += desc.id
+			descIDs[desc.id] = struct{}{}
+		}
+	}
+
+	r.mtx.RLock()
+	if _, exists := r.collectorsByID[collectorID]; !exists {
+		r.mtx.RUnlock()
+		return false
+	}
+	r.mtx.RUnlock()
+
+	r.mtx.Lock()
+	defer r.mtx.Unlock()
+
+	delete(r.collectorsByID, collectorID)
+	for id := range descIDs {
+		delete(r.descIDs, id)
+	}
+	// dimHashesByName is left untouched as those must be consistent
+	// throughout the lifetime of a program.
+	return true
+}
+
+// MustRegister implements Registerer.
+func (r *Registry) MustRegister(cs ...Collector) {
+	for _, c := range cs {
+		if err := r.Register(c); err != nil {
+			panic(err)
+		}
+	}
+}
+
+// Gather implements Gatherer.
+func (r *Registry) Gather() ([]*dto.MetricFamily, error) {
+	var (
+		metricChan        = make(chan Metric, capMetricChan)
+		metricHashes      = map[uint64]struct{}{}
+		dimHashes         = map[string]uint64{}
+		wg                sync.WaitGroup
+		errs              MultiError          // The collected errors to return in the end.
+		registeredDescIDs map[uint64]struct{} // Only used for pedantic checks
+	)
+
+	r.mtx.RLock()
+	metricFamiliesByName := make(map[string]*dto.MetricFamily, len(r.dimHashesByName))
+
+	// Scatter.
+	// (Collectors could be complex and slow, so we call them all at once.)
+	wg.Add(len(r.collectorsByID))
+	go func() {
+		wg.Wait()
+		close(metricChan)
+	}()
+	for _, collector := range r.collectorsByID {
+		go func(collector Collector) {
+			defer wg.Done()
+			collector.Collect(metricChan)
+		}(collector)
+	}
+
+	// In case pedantic checks are enabled, we have to copy the map before
+	// giving up the RLock.
+	if r.pedanticChecksEnabled {
+		registeredDescIDs = make(map[uint64]struct{}, len(r.descIDs))
+		for id := range r.descIDs {
+			registeredDescIDs[id] = struct{}{}
+		}
+	}
+
+	r.mtx.RUnlock()
+
+	// Drain metricChan in case of premature return.
+	defer func() {
+		for range metricChan {
+		}
+	}()
+
+	// Gather.
+	for metric := range metricChan {
+		// This could be done concurrently, too, but it required locking
+		// of metricFamiliesByName (and of metricHashes if checks are
+		// enabled). Most likely not worth it.
+		desc := metric.Desc()
+		dtoMetric := &dto.Metric{}
+		if err := metric.Write(dtoMetric); err != nil {
+			errs = append(errs, fmt.Errorf(
+				"error collecting metric %v: %s", desc, err,
+			))
+			continue
+		}
+		metricFamily, ok := metricFamiliesByName[desc.fqName]
+		if ok {
+			if metricFamily.GetHelp() != desc.help {
+				errs = append(errs, fmt.Errorf(
+					"collected metric %s %s has help %q but should have %q",
+					desc.fqName, dtoMetric, desc.help, metricFamily.GetHelp(),
+				))
+				continue
+			}
+			// TODO(beorn7): Simplify switch once Desc has type.
+			switch metricFamily.GetType() {
+			case dto.MetricType_COUNTER:
+				if dtoMetric.Counter == nil {
+					errs = append(errs, fmt.Errorf(
+						"collected metric %s %s should be a Counter",
+						desc.fqName, dtoMetric,
+					))
+					continue
+				}
+			case dto.MetricType_GAUGE:
+				if dtoMetric.Gauge == nil {
+					errs = append(errs, fmt.Errorf(
+						"collected metric %s %s should be a Gauge",
+						desc.fqName, dtoMetric,
+					))
+					continue
+				}
+			case dto.MetricType_SUMMARY:
+				if dtoMetric.Summary == nil {
+					errs = append(errs, fmt.Errorf(
+						"collected metric %s %s should be a Summary",
+						desc.fqName, dtoMetric,
+					))
+					continue
+				}
+			case dto.MetricType_UNTYPED:
+				if dtoMetric.Untyped == nil {
+					errs = append(errs, fmt.Errorf(
+						"collected metric %s %s should be Untyped",
+						desc.fqName, dtoMetric,
+					))
+					continue
+				}
+			case dto.MetricType_HISTOGRAM:
+				if dtoMetric.Histogram == nil {
+					errs = append(errs, fmt.Errorf(
+						"collected metric %s %s should be a Histogram",
+						desc.fqName, dtoMetric,
+					))
+					continue
+				}
+			default:
+				panic("encountered MetricFamily with invalid type")
+			}
+		} else {
+			metricFamily = &dto.MetricFamily{}
+			metricFamily.Name = proto.String(desc.fqName)
+			metricFamily.Help = proto.String(desc.help)
+			// TODO(beorn7): Simplify switch once Desc has type.
+			switch {
+			case dtoMetric.Gauge != nil:
+				metricFamily.Type = dto.MetricType_GAUGE.Enum()
+			case dtoMetric.Counter != nil:
+				metricFamily.Type = dto.MetricType_COUNTER.Enum()
+			case dtoMetric.Summary != nil:
+				metricFamily.Type = dto.MetricType_SUMMARY.Enum()
+			case dtoMetric.Untyped != nil:
+				metricFamily.Type = dto.MetricType_UNTYPED.Enum()
+			case dtoMetric.Histogram != nil:
+				metricFamily.Type = dto.MetricType_HISTOGRAM.Enum()
+			default:
+				errs = append(errs, fmt.Errorf(
+					"empty metric collected: %s", dtoMetric,
+				))
+				continue
+			}
+			metricFamiliesByName[desc.fqName] = metricFamily
+		}
+		if err := checkMetricConsistency(metricFamily, dtoMetric, metricHashes, dimHashes); err != nil {
+			errs = append(errs, err)
+			continue
+		}
+		if r.pedanticChecksEnabled {
+			// Is the desc registered at all?
+			if _, exist := registeredDescIDs[desc.id]; !exist {
+				errs = append(errs, fmt.Errorf(
+					"collected metric %s %s with unregistered descriptor %s",
+					metricFamily.GetName(), dtoMetric, desc,
+				))
+				continue
+			}
+			if err := checkDescConsistency(metricFamily, dtoMetric, desc); err != nil {
+				errs = append(errs, err)
+				continue
+			}
+		}
+		metricFamily.Metric = append(metricFamily.Metric, dtoMetric)
+	}
+	return normalizeMetricFamilies(metricFamiliesByName), errs.MaybeUnwrap()
+}
+
+// Gatherers is a slice of Gatherer instances that implements the Gatherer
+// interface itself. Its Gather method calls Gather on all Gatherers in the
+// slice in order and returns the merged results. Errors returned from the
+// Gather calles are all returned in a flattened MultiError. Duplicate and
+// inconsistent Metrics are skipped (first occurrence in slice order wins) and
+// reported in the returned error.
+//
+// Gatherers can be used to merge the Gather results from multiple
+// Registries. It also provides a way to directly inject existing MetricFamily
+// protobufs into the gathering by creating a custom Gatherer with a Gather
+// method that simply returns the existing MetricFamily protobufs. Note that no
+// registration is involved (in contrast to Collector registration), so
+// obviously registration-time checks cannot happen. Any inconsistencies between
+// the gathered MetricFamilies are reported as errors by the Gather method, and
+// inconsistent Metrics are dropped. Invalid parts of the MetricFamilies
+// (e.g. syntactically invalid metric or label names) will go undetected.
+type Gatherers []Gatherer
+
+// Gather implements Gatherer.
+func (gs Gatherers) Gather() ([]*dto.MetricFamily, error) {
+	var (
+		metricFamiliesByName = map[string]*dto.MetricFamily{}
+		metricHashes         = map[uint64]struct{}{}
+		dimHashes            = map[string]uint64{}
+		errs                 MultiError // The collected errors to return in the end.
+	)
+
+	for i, g := range gs {
+		mfs, err := g.Gather()
+		if err != nil {
+			if multiErr, ok := err.(MultiError); ok {
+				for _, err := range multiErr {
+					errs = append(errs, fmt.Errorf("[from Gatherer #%d] %s", i+1, err))
+				}
+			} else {
+				errs = append(errs, fmt.Errorf("[from Gatherer #%d] %s", i+1, err))
+			}
+		}
+		for _, mf := range mfs {
+			existingMF, exists := metricFamiliesByName[mf.GetName()]
+			if exists {
+				if existingMF.GetHelp() != mf.GetHelp() {
+					errs = append(errs, fmt.Errorf(
+						"gathered metric family %s has help %q but should have %q",
+						mf.GetName(), mf.GetHelp(), existingMF.GetHelp(),
+					))
+					continue
+				}
+				if existingMF.GetType() != mf.GetType() {
+					errs = append(errs, fmt.Errorf(
+						"gathered metric family %s has type %s but should have %s",
+						mf.GetName(), mf.GetType(), existingMF.GetType(),
+					))
+					continue
+				}
+			} else {
+				existingMF = &dto.MetricFamily{}
+				existingMF.Name = mf.Name
+				existingMF.Help = mf.Help
+				existingMF.Type = mf.Type
+				metricFamiliesByName[mf.GetName()] = existingMF
+			}
+			for _, m := range mf.Metric {
+				if err := checkMetricConsistency(existingMF, m, metricHashes, dimHashes); err != nil {
+					errs = append(errs, err)
+					continue
+				}
+				existingMF.Metric = append(existingMF.Metric, m)
+			}
+		}
+	}
+	return normalizeMetricFamilies(metricFamiliesByName), errs.MaybeUnwrap()
+}
+
+// metricSorter is a sortable slice of *dto.Metric.
+type metricSorter []*dto.Metric
+
+func (s metricSorter) Len() int {
+	return len(s)
+}
+
+func (s metricSorter) Swap(i, j int) {
+	s[i], s[j] = s[j], s[i]
+}
+
+func (s metricSorter) Less(i, j int) bool {
+	if len(s[i].Label) != len(s[j].Label) {
+		// This should not happen. The metrics are
+		// inconsistent. However, we have to deal with the fact, as
+		// people might use custom collectors or metric family injection
+		// to create inconsistent metrics. So let's simply compare the
+		// number of labels in this case. That will still yield
+		// reproducible sorting.
+		return len(s[i].Label) < len(s[j].Label)
+	}
+	for n, lp := range s[i].Label {
+		vi := lp.GetValue()
+		vj := s[j].Label[n].GetValue()
+		if vi != vj {
+			return vi < vj
+		}
+	}
+
+	// We should never arrive here. Multiple metrics with the same
+	// label set in the same scrape will lead to undefined ingestion
+	// behavior. However, as above, we have to provide stable sorting
+	// here, even for inconsistent metrics. So sort equal metrics
+	// by their timestamp, with missing timestamps (implying "now")
+	// coming last.
+	if s[i].TimestampMs == nil {
+		return false
+	}
+	if s[j].TimestampMs == nil {
+		return true
+	}
+	return s[i].GetTimestampMs() < s[j].GetTimestampMs()
+}
+
+// normalizeMetricFamilies returns a MetricFamily slice with empty
+// MetricFamilies pruned and the remaining MetricFamilies sorted by name within
+// the slice, with the contained Metrics sorted within each MetricFamily.
+func normalizeMetricFamilies(metricFamiliesByName map[string]*dto.MetricFamily) []*dto.MetricFamily {
+	for _, mf := range metricFamiliesByName {
+		sort.Sort(metricSorter(mf.Metric))
+	}
+	names := make([]string, 0, len(metricFamiliesByName))
+	for name, mf := range metricFamiliesByName {
+		if len(mf.Metric) > 0 {
+			names = append(names, name)
+		}
+	}
+	sort.Strings(names)
+	result := make([]*dto.MetricFamily, 0, len(names))
+	for _, name := range names {
+		result = append(result, metricFamiliesByName[name])
+	}
+	return result
+}
+
+// checkMetricConsistency checks if the provided Metric is consistent with the
+// provided MetricFamily. It also hashed the Metric labels and the MetricFamily
+// name. If the resulting hash is alread in the provided metricHashes, an error
+// is returned. If not, it is added to metricHashes. The provided dimHashes maps
+// MetricFamily names to their dimHash (hashed sorted label names). If dimHashes
+// doesn't yet contain a hash for the provided MetricFamily, it is
+// added. Otherwise, an error is returned if the existing dimHashes in not equal
+// the calculated dimHash.
+func checkMetricConsistency(
+	metricFamily *dto.MetricFamily,
+	dtoMetric *dto.Metric,
+	metricHashes map[uint64]struct{},
+	dimHashes map[string]uint64,
+) error {
+	// Type consistency with metric family.
+	if metricFamily.GetType() == dto.MetricType_GAUGE && dtoMetric.Gauge == nil ||
+		metricFamily.GetType() == dto.MetricType_COUNTER && dtoMetric.Counter == nil ||
+		metricFamily.GetType() == dto.MetricType_SUMMARY && dtoMetric.Summary == nil ||
+		metricFamily.GetType() == dto.MetricType_HISTOGRAM && dtoMetric.Histogram == nil ||
+		metricFamily.GetType() == dto.MetricType_UNTYPED && dtoMetric.Untyped == nil {
+		return fmt.Errorf(
+			"collected metric %s %s is not a %s",
+			metricFamily.GetName(), dtoMetric, metricFamily.GetType(),
+		)
+	}
+
+	for _, labelPair := range dtoMetric.GetLabel() {
+		if !utf8.ValidString(*labelPair.Value) {
+			return fmt.Errorf("collected metric's label %s is not utf8: %#v", *labelPair.Name, *labelPair.Value)
+		}
+	}
+
+	// Is the metric unique (i.e. no other metric with the same name and the same label values)?
+	h := hashNew()
+	h = hashAdd(h, metricFamily.GetName())
+	h = hashAddByte(h, separatorByte)
+	dh := hashNew()
+	// Make sure label pairs are sorted. We depend on it for the consistency
+	// check.
+	sort.Sort(LabelPairSorter(dtoMetric.Label))
+	for _, lp := range dtoMetric.Label {
+		h = hashAdd(h, lp.GetValue())
+		h = hashAddByte(h, separatorByte)
+		dh = hashAdd(dh, lp.GetName())
+		dh = hashAddByte(dh, separatorByte)
+	}
+	if _, exists := metricHashes[h]; exists {
+		return fmt.Errorf(
+			"collected metric %s %s was collected before with the same name and label values",
+			metricFamily.GetName(), dtoMetric,
+		)
+	}
+	if dimHash, ok := dimHashes[metricFamily.GetName()]; ok {
+		if dimHash != dh {
+			return fmt.Errorf(
+				"collected metric %s %s has label dimensions inconsistent with previously collected metrics in the same metric family",
+				metricFamily.GetName(), dtoMetric,
+			)
+		}
+	} else {
+		dimHashes[metricFamily.GetName()] = dh
+	}
+	metricHashes[h] = struct{}{}
+	return nil
+}
+
+func checkDescConsistency(
+	metricFamily *dto.MetricFamily,
+	dtoMetric *dto.Metric,
+	desc *Desc,
+) error {
+	// Desc help consistency with metric family help.
+	if metricFamily.GetHelp() != desc.help {
+		return fmt.Errorf(
+			"collected metric %s %s has help %q but should have %q",
+			metricFamily.GetName(), dtoMetric, metricFamily.GetHelp(), desc.help,
+		)
+	}
+
+	// Is the desc consistent with the content of the metric?
+	lpsFromDesc := make([]*dto.LabelPair, 0, len(dtoMetric.Label))
+	lpsFromDesc = append(lpsFromDesc, desc.constLabelPairs...)
+	for _, l := range desc.variableLabels {
+		lpsFromDesc = append(lpsFromDesc, &dto.LabelPair{
+			Name: proto.String(l),
+		})
+	}
+	if len(lpsFromDesc) != len(dtoMetric.Label) {
+		return fmt.Errorf(
+			"labels in collected metric %s %s are inconsistent with descriptor %s",
+			metricFamily.GetName(), dtoMetric, desc,
+		)
+	}
+	sort.Sort(LabelPairSorter(lpsFromDesc))
+	for i, lpFromDesc := range lpsFromDesc {
+		lpFromMetric := dtoMetric.Label[i]
+		if lpFromDesc.GetName() != lpFromMetric.GetName() ||
+			lpFromDesc.Value != nil && lpFromDesc.GetValue() != lpFromMetric.GetValue() {
+			return fmt.Errorf(
+				"labels in collected metric %s %s are inconsistent with descriptor %s",
+				metricFamily.GetName(), dtoMetric, desc,
+			)
+		}
+	}
+	return nil
+}

vendor/github.com/prometheus/client_golang/prometheus/registry_test.go

@@ -0,0 +1,590 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Copyright (c) 2013, The Prometheus Authors
+// All rights reserved.
+//
+// Use of this source code is governed by a BSD-style license that can be found
+// in the LICENSE file.
+
+package prometheus_test
+
+import (
+	"bytes"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	dto "github.com/prometheus/client_model/go"
+
+	"github.com/golang/protobuf/proto"
+	"github.com/prometheus/common/expfmt"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+func testHandler(t testing.TB) {
+
+	metricVec := prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name:        "name",
+			Help:        "docstring",
+			ConstLabels: prometheus.Labels{"constname": "constvalue"},
+		},
+		[]string{"labelname"},
+	)
+
+	metricVec.WithLabelValues("val1").Inc()
+	metricVec.WithLabelValues("val2").Inc()
+
+	externalMetricFamily := &dto.MetricFamily{
+		Name: proto.String("externalname"),
+		Help: proto.String("externaldocstring"),
+		Type: dto.MetricType_COUNTER.Enum(),
+		Metric: []*dto.Metric{
+			{
+				Label: []*dto.LabelPair{
+					{
+						Name:  proto.String("externalconstname"),
+						Value: proto.String("externalconstvalue"),
+					},
+					{
+						Name:  proto.String("externallabelname"),
+						Value: proto.String("externalval1"),
+					},
+				},
+				Counter: &dto.Counter{
+					Value: proto.Float64(1),
+				},
+			},
+		},
+	}
+	externalBuf := &bytes.Buffer{}
+	enc := expfmt.NewEncoder(externalBuf, expfmt.FmtProtoDelim)
+	if err := enc.Encode(externalMetricFamily); err != nil {
+		t.Fatal(err)
+	}
+	externalMetricFamilyAsBytes := externalBuf.Bytes()
+	externalMetricFamilyAsText := []byte(`# HELP externalname externaldocstring
+# TYPE externalname counter
+externalname{externalconstname="externalconstvalue",externallabelname="externalval1"} 1
+`)
+	externalMetricFamilyAsProtoText := []byte(`name: "externalname"
+help: "externaldocstring"
+type: COUNTER
+metric: <
+  label: <
+    name: "externalconstname"
+    value: "externalconstvalue"
+  >
+  label: <
+    name: "externallabelname"
+    value: "externalval1"
+  >
+  counter: <
+    value: 1
+  >
+>
+
+`)
+	externalMetricFamilyAsProtoCompactText := []byte(`name:"externalname" help:"externaldocstring" type:COUNTER metric:<label:<name:"externalconstname" value:"externalconstvalue" > label:<name:"externallabelname" value:"externalval1" > counter:<value:1 > > 
+`)
+
+	expectedMetricFamily := &dto.MetricFamily{
+		Name: proto.String("name"),
+		Help: proto.String("docstring"),
+		Type: dto.MetricType_COUNTER.Enum(),
+		Metric: []*dto.Metric{
+			{
+				Label: []*dto.LabelPair{
+					{
+						Name:  proto.String("constname"),
+						Value: proto.String("constvalue"),
+					},
+					{
+						Name:  proto.String("labelname"),
+						Value: proto.String("val1"),
+					},
+				},
+				Counter: &dto.Counter{
+					Value: proto.Float64(1),
+				},
+			},
+			{
+				Label: []*dto.LabelPair{
+					{
+						Name:  proto.String("constname"),
+						Value: proto.String("constvalue"),
+					},
+					{
+						Name:  proto.String("labelname"),
+						Value: proto.String("val2"),
+					},
+				},
+				Counter: &dto.Counter{
+					Value: proto.Float64(1),
+				},
+			},
+		},
+	}
+	buf := &bytes.Buffer{}
+	enc = expfmt.NewEncoder(buf, expfmt.FmtProtoDelim)
+	if err := enc.Encode(expectedMetricFamily); err != nil {
+		t.Fatal(err)
+	}
+	expectedMetricFamilyAsBytes := buf.Bytes()
+	expectedMetricFamilyAsText := []byte(`# HELP name docstring
+# TYPE name counter
+name{constname="constvalue",labelname="val1"} 1
+name{constname="constvalue",labelname="val2"} 1
+`)
+	expectedMetricFamilyAsProtoText := []byte(`name: "name"
+help: "docstring"
+type: COUNTER
+metric: <
+  label: <
+    name: "constname"
+    value: "constvalue"
+  >
+  label: <
+    name: "labelname"
+    value: "val1"
+  >
+  counter: <
+    value: 1
+  >
+>
+metric: <
+  label: <
+    name: "constname"
+    value: "constvalue"
+  >
+  label: <
+    name: "labelname"
+    value: "val2"
+  >
+  counter: <
+    value: 1
+  >
+>
+
+`)
+	expectedMetricFamilyAsProtoCompactText := []byte(`name:"name" help:"docstring" type:COUNTER metric:<label:<name:"constname" value:"constvalue" > label:<name:"labelname" value:"val1" > counter:<value:1 > > metric:<label:<name:"constname" value:"constvalue" > label:<name:"labelname" value:"val2" > counter:<value:1 > > 
+`)
+
+	externalMetricFamilyWithSameName := &dto.MetricFamily{
+		Name: proto.String("name"),
+		Help: proto.String("docstring"),
+		Type: dto.MetricType_COUNTER.Enum(),
+		Metric: []*dto.Metric{
+			{
+				Label: []*dto.LabelPair{
+					{
+						Name:  proto.String("constname"),
+						Value: proto.String("constvalue"),
+					},
+					{
+						Name:  proto.String("labelname"),
+						Value: proto.String("different_val"),
+					},
+				},
+				Counter: &dto.Counter{
+					Value: proto.Float64(42),
+				},
+			},
+		},
+	}
+
+	expectedMetricFamilyMergedWithExternalAsProtoCompactText := []byte(`name:"name" help:"docstring" type:COUNTER metric:<label:<name:"constname" value:"constvalue" > label:<name:"labelname" value:"different_val" > counter:<value:42 > > metric:<label:<name:"constname" value:"constvalue" > label:<name:"labelname" value:"val1" > counter:<value:1 > > metric:<label:<name:"constname" value:"constvalue" > label:<name:"labelname" value:"val2" > counter:<value:1 > > 
+`)
+
+	externalMetricFamilyWithInvalidLabelValue := &dto.MetricFamily{
+		Name: proto.String("name"),
+		Help: proto.String("docstring"),
+		Type: dto.MetricType_COUNTER.Enum(),
+		Metric: []*dto.Metric{
+			{
+				Label: []*dto.LabelPair{
+					{
+						Name:  proto.String("constname"),
+						Value: proto.String("\xFF"),
+					},
+					{
+						Name:  proto.String("labelname"),
+						Value: proto.String("different_val"),
+					},
+				},
+				Counter: &dto.Counter{
+					Value: proto.Float64(42),
+				},
+			},
+		},
+	}
+
+	expectedMetricFamilyInvalidLabelValueAsText := []byte(`An error has occurred during metrics gathering:
+
+collected metric's label constname is not utf8: "\xff"
+`)
+
+	type output struct {
+		headers map[string]string
+		body    []byte
+	}
+
+	var scenarios = []struct {
+		headers    map[string]string
+		out        output
+		collector  prometheus.Collector
+		externalMF []*dto.MetricFamily
+	}{
+		{ // 0
+			headers: map[string]string{
+				"Accept": "foo/bar;q=0.2, dings/bums;q=0.8",
+			},
+			out: output{
+				headers: map[string]string{
+					"Content-Type": `text/plain; version=0.0.4`,
+				},
+				body: []byte{},
+			},
+		},
+		{ // 1
+			headers: map[string]string{
+				"Accept": "foo/bar;q=0.2, application/quark;q=0.8",
+			},
+			out: output{
+				headers: map[string]string{
+					"Content-Type": `text/plain; version=0.0.4`,
+				},
+				body: []byte{},
+			},
+		},
+		{ // 2
+			headers: map[string]string{
+				"Accept": "foo/bar;q=0.2, application/vnd.google.protobuf;proto=io.prometheus.client.MetricFamily;encoding=bla;q=0.8",
+			},
+			out: output{
+				headers: map[string]string{
+					"Content-Type": `text/plain; version=0.0.4`,
+				},
+				body: []byte{},
+			},
+		},
+		{ // 3
+			headers: map[string]string{
+				"Accept": "text/plain;q=0.2, application/vnd.google.protobuf;proto=io.prometheus.client.MetricFamily;encoding=delimited;q=0.8",
+			},
+			out: output{
+				headers: map[string]string{
+					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=delimited`,
+				},
+				body: []byte{},
+			},
+		},
+		{ // 4
+			headers: map[string]string{
+				"Accept": "application/json",
+			},
+			out: output{
+				headers: map[string]string{
+					"Content-Type": `text/plain; version=0.0.4`,
+				},
+				body: expectedMetricFamilyAsText,
+			},
+			collector: metricVec,
+		},
+		{ // 5
+			headers: map[string]string{
+				"Accept": "application/vnd.google.protobuf;proto=io.prometheus.client.MetricFamily;encoding=delimited",
+			},
+			out: output{
+				headers: map[string]string{
+					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=delimited`,
+				},
+				body: expectedMetricFamilyAsBytes,
+			},
+			collector: metricVec,
+		},
+		{ // 6
+			headers: map[string]string{
+				"Accept": "application/json",
+			},
+			out: output{
+				headers: map[string]string{
+					"Content-Type": `text/plain; version=0.0.4`,
+				},
+				body: externalMetricFamilyAsText,
+			},
+			externalMF: []*dto.MetricFamily{externalMetricFamily},
+		},
+		{ // 7
+			headers: map[string]string{
+				"Accept": "application/vnd.google.protobuf;proto=io.prometheus.client.MetricFamily;encoding=delimited",
+			},
+			out: output{
+				headers: map[string]string{
+					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=delimited`,
+				},
+				body: externalMetricFamilyAsBytes,
+			},
+			externalMF: []*dto.MetricFamily{externalMetricFamily},
+		},
+		{ // 8
+			headers: map[string]string{
+				"Accept": "application/vnd.google.protobuf;proto=io.prometheus.client.MetricFamily;encoding=delimited",
+			},
+			out: output{
+				headers: map[string]string{
+					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=delimited`,
+				},
+				body: bytes.Join(
+					[][]byte{
+						externalMetricFamilyAsBytes,
+						expectedMetricFamilyAsBytes,
+					},
+					[]byte{},
+				),
+			},
+			collector:  metricVec,
+			externalMF: []*dto.MetricFamily{externalMetricFamily},
+		},
+		{ // 9
+			headers: map[string]string{
+				"Accept": "text/plain",
+			},
+			out: output{
+				headers: map[string]string{
+					"Content-Type": `text/plain; version=0.0.4`,
+				},
+				body: []byte{},
+			},
+		},
+		{ // 10
+			headers: map[string]string{
+				"Accept": "application/vnd.google.protobuf;proto=io.prometheus.client.MetricFamily;encoding=bla;q=0.2, text/plain;q=0.5",
+			},
+			out: output{
+				headers: map[string]string{
+					"Content-Type": `text/plain; version=0.0.4`,
+				},
+				body: expectedMetricFamilyAsText,
+			},
+			collector: metricVec,
+		},
+		{ // 11
+			headers: map[string]string{
+				"Accept": "application/vnd.google.protobuf;proto=io.prometheus.client.MetricFamily;encoding=bla;q=0.2, text/plain;q=0.5;version=0.0.4",
+			},
+			out: output{
+				headers: map[string]string{
+					"Content-Type": `text/plain; version=0.0.4`,
+				},
+				body: bytes.Join(
+					[][]byte{
+						externalMetricFamilyAsText,
+						expectedMetricFamilyAsText,
+					},
+					[]byte{},
+				),
+			},
+			collector:  metricVec,
+			externalMF: []*dto.MetricFamily{externalMetricFamily},
+		},
+		{ // 12
+			headers: map[string]string{
+				"Accept": "application/vnd.google.protobuf;proto=io.prometheus.client.MetricFamily;encoding=delimited;q=0.2, text/plain;q=0.5;version=0.0.2",
+			},
+			out: output{
+				headers: map[string]string{
+					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=delimited`,
+				},
+				body: bytes.Join(
+					[][]byte{
+						externalMetricFamilyAsBytes,
+						expectedMetricFamilyAsBytes,
+					},
+					[]byte{},
+				),
+			},
+			collector:  metricVec,
+			externalMF: []*dto.MetricFamily{externalMetricFamily},
+		},
+		{ // 13
+			headers: map[string]string{
+				"Accept": "application/vnd.google.protobuf;proto=io.prometheus.client.MetricFamily;encoding=text;q=0.5, application/vnd.google.protobuf;proto=io.prometheus.client.MetricFamily;encoding=delimited;q=0.4",
+			},
+			out: output{
+				headers: map[string]string{
+					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=text`,
+				},
+				body: bytes.Join(
+					[][]byte{
+						externalMetricFamilyAsProtoText,
+						expectedMetricFamilyAsProtoText,
+					},
+					[]byte{},
+				),
+			},
+			collector:  metricVec,
+			externalMF: []*dto.MetricFamily{externalMetricFamily},
+		},
+		{ // 14
+			headers: map[string]string{
+				"Accept": "application/vnd.google.protobuf;proto=io.prometheus.client.MetricFamily;encoding=compact-text",
+			},
+			out: output{
+				headers: map[string]string{
+					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=compact-text`,
+				},
+				body: bytes.Join(
+					[][]byte{
+						externalMetricFamilyAsProtoCompactText,
+						expectedMetricFamilyAsProtoCompactText,
+					},
+					[]byte{},
+				),
+			},
+			collector:  metricVec,
+			externalMF: []*dto.MetricFamily{externalMetricFamily},
+		},
+		{ // 15
+			headers: map[string]string{
+				"Accept": "application/vnd.google.protobuf;proto=io.prometheus.client.MetricFamily;encoding=compact-text",
+			},
+			out: output{
+				headers: map[string]string{
+					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=compact-text`,
+				},
+				body: bytes.Join(
+					[][]byte{
+						externalMetricFamilyAsProtoCompactText,
+						expectedMetricFamilyMergedWithExternalAsProtoCompactText,
+					},
+					[]byte{},
+				),
+			},
+			collector: metricVec,
+			externalMF: []*dto.MetricFamily{
+				externalMetricFamily,
+				externalMetricFamilyWithSameName,
+			},
+		},
+		{ // 16
+			headers: map[string]string{
+				"Accept": "application/vnd.google.protobuf;proto=io.prometheus.client.MetricFamily;encoding=compact-text",
+			},
+			out: output{
+				headers: map[string]string{
+					"Content-Type": `text/plain; charset=utf-8`,
+				},
+				body: expectedMetricFamilyInvalidLabelValueAsText,
+			},
+			collector: metricVec,
+			externalMF: []*dto.MetricFamily{
+				externalMetricFamily,
+				externalMetricFamilyWithInvalidLabelValue,
+			},
+		},
+	}
+	for i, scenario := range scenarios {
+		registry := prometheus.NewPedanticRegistry()
+		gatherer := prometheus.Gatherer(registry)
+		if scenario.externalMF != nil {
+			gatherer = prometheus.Gatherers{
+				registry,
+				prometheus.GathererFunc(func() ([]*dto.MetricFamily, error) {
+					return scenario.externalMF, nil
+				}),
+			}
+		}
+
+		if scenario.collector != nil {
+			registry.Register(scenario.collector)
+		}
+		writer := httptest.NewRecorder()
+		handler := prometheus.InstrumentHandler("prometheus", promhttp.HandlerFor(gatherer, promhttp.HandlerOpts{}))
+		request, _ := http.NewRequest("GET", "/", nil)
+		for key, value := range scenario.headers {
+			request.Header.Add(key, value)
+		}
+		handler(writer, request)
+
+		for key, value := range scenario.out.headers {
+			if writer.HeaderMap.Get(key) != value {
+				t.Errorf(
+					"%d. expected %q for header %q, got %q",
+					i, value, key, writer.Header().Get(key),
+				)
+			}
+		}
+
+		if !bytes.Equal(scenario.out.body, writer.Body.Bytes()) {
+			t.Errorf(
+				"%d. expected body:\n%s\ngot body:\n%s\n",
+				i, scenario.out.body, writer.Body.Bytes(),
+			)
+		}
+	}
+}
+
+func TestHandler(t *testing.T) {
+	testHandler(t)
+}
+
+func BenchmarkHandler(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		testHandler(b)
+	}
+}
+
+func TestRegisterWithOrGet(t *testing.T) {
+	// Replace the default registerer just to be sure. This is bad, but this
+	// whole test will go away once RegisterOrGet is removed.
+	oldRegisterer := prometheus.DefaultRegisterer
+	defer func() {
+		prometheus.DefaultRegisterer = oldRegisterer
+	}()
+	prometheus.DefaultRegisterer = prometheus.NewRegistry()
+	original := prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "test",
+			Help: "help",
+		},
+		[]string{"foo", "bar"},
+	)
+	equalButNotSame := prometheus.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "test",
+			Help: "help",
+		},
+		[]string{"foo", "bar"},
+	)
+	var err error
+	if err = prometheus.Register(original); err != nil {
+		t.Fatal(err)
+	}
+	if err = prometheus.Register(equalButNotSame); err == nil {
+		t.Fatal("expected error when registringe equal collector")
+	}
+	if are, ok := err.(prometheus.AlreadyRegisteredError); ok {
+		if are.ExistingCollector != original {
+			t.Error("expected original collector but got something else")
+		}
+		if are.ExistingCollector == equalButNotSame {
+			t.Error("expected original callector but got new one")
+		}
+	} else {
+		t.Error("unexpected error:", err)
+	}
+}

vendor/github.com/prometheus/client_golang/prometheus/summary.go

@@ -0,0 +1,572 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+import (
+	"fmt"
+	"math"
+	"sort"
+	"sync"
+	"time"
+
+	"github.com/beorn7/perks/quantile"
+	"github.com/golang/protobuf/proto"
+
+	dto "github.com/prometheus/client_model/go"
+)
+
+// quantileLabel is used for the label that defines the quantile in a
+// summary.
+const quantileLabel = "quantile"
+
+// A Summary captures individual observations from an event or sample stream and
+// summarizes them in a manner similar to traditional summary statistics: 1. sum
+// of observations, 2. observation count, 3. rank estimations.
+//
+// A typical use-case is the observation of request latencies. By default, a
+// Summary provides the median, the 90th and the 99th percentile of the latency
+// as rank estimations.
+//
+// Note that the rank estimations cannot be aggregated in a meaningful way with
+// the Prometheus query language (i.e. you cannot average or add them). If you
+// need aggregatable quantiles (e.g. you want the 99th percentile latency of all
+// queries served across all instances of a service), consider the Histogram
+// metric type. See the Prometheus documentation for more details.
+//
+// To create Summary instances, use NewSummary.
+type Summary interface {
+	Metric
+	Collector
+
+	// Observe adds a single observation to the summary.
+	Observe(float64)
+}
+
+// DefObjectives are the default Summary quantile values.
+//
+// Deprecated: DefObjectives will not be used as the default objectives in
+// v0.10 of the library. The default Summary will have no quantiles then.
+var (
+	DefObjectives = map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001}
+
+	errQuantileLabelNotAllowed = fmt.Errorf(
+		"%q is not allowed as label name in summaries", quantileLabel,
+	)
+)
+
+// Default values for SummaryOpts.
+const (
+	// DefMaxAge is the default duration for which observations stay
+	// relevant.
+	DefMaxAge time.Duration = 10 * time.Minute
+	// DefAgeBuckets is the default number of buckets used to calculate the
+	// age of observations.
+	DefAgeBuckets = 5
+	// DefBufCap is the standard buffer size for collecting Summary observations.
+	DefBufCap = 500
+)
+
+// SummaryOpts bundles the options for creating a Summary metric. It is
+// mandatory to set Name and Help to a non-empty string. All other fields are
+// optional and can safely be left at their zero value.
+type SummaryOpts struct {
+	// Namespace, Subsystem, and Name are components of the fully-qualified
+	// name of the Summary (created by joining these components with
+	// "_"). Only Name is mandatory, the others merely help structuring the
+	// name. Note that the fully-qualified name of the Summary must be a
+	// valid Prometheus metric name.
+	Namespace string
+	Subsystem string
+	Name      string
+
+	// Help provides information about this Summary. Mandatory!
+	//
+	// Metrics with the same fully-qualified name must have the same Help
+	// string.
+	Help string
+
+	// ConstLabels are used to attach fixed labels to this
+	// Summary. Summaries with the same fully-qualified name must have the
+	// same label names in their ConstLabels.
+	//
+	// Note that in most cases, labels have a value that varies during the
+	// lifetime of a process. Those labels are usually managed with a
+	// SummaryVec. ConstLabels serve only special purposes. One is for the
+	// special case where the value of a label does not change during the
+	// lifetime of a process, e.g. if the revision of the running binary is
+	// put into a label. Another, more advanced purpose is if more than one
+	// Collector needs to collect Summaries with the same fully-qualified
+	// name. In that case, those Summaries must differ in the values of
+	// their ConstLabels. See the Collector examples.
+	//
+	// If the value of a label never changes (not even between binaries),
+	// that label most likely should not be a label at all (but part of the
+	// metric name).
+	ConstLabels Labels
+
+	// Objectives defines the quantile rank estimates with their respective
+	// absolute error. If Objectives[q] = e, then the value reported for q
+	// will be the φ-quantile value for some φ between q-e and q+e.  The
+	// default value is DefObjectives. It is used if Objectives is left at
+	// its zero value (i.e. nil). To create a Summary without Objectives,
+	// set it to an empty map (i.e. map[float64]float64{}).
+	//
+	// Deprecated: Note that the current value of DefObjectives is
+	// deprecated. It will be replaced by an empty map in v0.10 of the
+	// library. Please explicitly set Objectives to the desired value.
+	Objectives map[float64]float64
+
+	// MaxAge defines the duration for which an observation stays relevant
+	// for the summary. Must be positive. The default value is DefMaxAge.
+	MaxAge time.Duration
+
+	// AgeBuckets is the number of buckets used to exclude observations that
+	// are older than MaxAge from the summary. A higher number has a
+	// resource penalty, so only increase it if the higher resolution is
+	// really required. For very high observation rates, you might want to
+	// reduce the number of age buckets. With only one age bucket, you will
+	// effectively see a complete reset of the summary each time MaxAge has
+	// passed. The default value is DefAgeBuckets.
+	AgeBuckets uint32
+
+	// BufCap defines the default sample stream buffer size.  The default
+	// value of DefBufCap should suffice for most uses. If there is a need
+	// to increase the value, a multiple of 500 is recommended (because that
+	// is the internal buffer size of the underlying package
+	// "github.com/bmizerany/perks/quantile").
+	BufCap uint32
+}
+
+// Great fuck-up with the sliding-window decay algorithm... The Merge method of
+// perk/quantile is actually not working as advertised - and it might be
+// unfixable, as the underlying algorithm is apparently not capable of merging
+// summaries in the first place. To avoid using Merge, we are currently adding
+// observations to _each_ age bucket, i.e. the effort to add a sample is
+// essentially multiplied by the number of age buckets. When rotating age
+// buckets, we empty the previous head stream. On scrape time, we simply take
+// the quantiles from the head stream (no merging required). Result: More effort
+// on observation time, less effort on scrape time, which is exactly the
+// opposite of what we try to accomplish, but at least the results are correct.
+//
+// The quite elegant previous contraption to merge the age buckets efficiently
+// on scrape time (see code up commit 6b9530d72ea715f0ba612c0120e6e09fbf1d49d0)
+// can't be used anymore.
+
+// NewSummary creates a new Summary based on the provided SummaryOpts.
+func NewSummary(opts SummaryOpts) Summary {
+	return newSummary(
+		NewDesc(
+			BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
+			opts.Help,
+			nil,
+			opts.ConstLabels,
+		),
+		opts,
+	)
+}
+
+func newSummary(desc *Desc, opts SummaryOpts, labelValues ...string) Summary {
+	if len(desc.variableLabels) != len(labelValues) {
+		panic(errInconsistentCardinality)
+	}
+
+	for _, n := range desc.variableLabels {
+		if n == quantileLabel {
+			panic(errQuantileLabelNotAllowed)
+		}
+	}
+	for _, lp := range desc.constLabelPairs {
+		if lp.GetName() == quantileLabel {
+			panic(errQuantileLabelNotAllowed)
+		}
+	}
+
+	if opts.Objectives == nil {
+		opts.Objectives = DefObjectives
+	}
+
+	if opts.MaxAge < 0 {
+		panic(fmt.Errorf("illegal max age MaxAge=%v", opts.MaxAge))
+	}
+	if opts.MaxAge == 0 {
+		opts.MaxAge = DefMaxAge
+	}
+
+	if opts.AgeBuckets == 0 {
+		opts.AgeBuckets = DefAgeBuckets
+	}
+
+	if opts.BufCap == 0 {
+		opts.BufCap = DefBufCap
+	}
+
+	s := &summary{
+		desc: desc,
+
+		objectives:       opts.Objectives,
+		sortedObjectives: make([]float64, 0, len(opts.Objectives)),
+
+		labelPairs: makeLabelPairs(desc, labelValues),
+
+		hotBuf:         make([]float64, 0, opts.BufCap),
+		coldBuf:        make([]float64, 0, opts.BufCap),
+		streamDuration: opts.MaxAge / time.Duration(opts.AgeBuckets),
+	}
+	s.headStreamExpTime = time.Now().Add(s.streamDuration)
+	s.hotBufExpTime = s.headStreamExpTime
+
+	for i := uint32(0); i < opts.AgeBuckets; i++ {
+		s.streams = append(s.streams, s.newStream())
+	}
+	s.headStream = s.streams[0]
+
+	for qu := range s.objectives {
+		s.sortedObjectives = append(s.sortedObjectives, qu)
+	}
+	sort.Float64s(s.sortedObjectives)
+
+	s.init(s) // Init self-collection.
+	return s
+}
+
+type summary struct {
+	selfCollector
+
+	bufMtx sync.Mutex // Protects hotBuf and hotBufExpTime.
+	mtx    sync.Mutex // Protects every other moving part.
+	// Lock bufMtx before mtx if both are needed.
+
+	desc *Desc
+
+	objectives       map[float64]float64
+	sortedObjectives []float64
+
+	labelPairs []*dto.LabelPair
+
+	sum float64
+	cnt uint64
+
+	hotBuf, coldBuf []float64
+
+	streams                          []*quantile.Stream
+	streamDuration                   time.Duration
+	headStream                       *quantile.Stream
+	headStreamIdx                    int
+	headStreamExpTime, hotBufExpTime time.Time
+}
+
+func (s *summary) Desc() *Desc {
+	return s.desc
+}
+
+func (s *summary) Observe(v float64) {
+	s.bufMtx.Lock()
+	defer s.bufMtx.Unlock()
+
+	now := time.Now()
+	if now.After(s.hotBufExpTime) {
+		s.asyncFlush(now)
+	}
+	s.hotBuf = append(s.hotBuf, v)
+	if len(s.hotBuf) == cap(s.hotBuf) {
+		s.asyncFlush(now)
+	}
+}
+
+func (s *summary) Write(out *dto.Metric) error {
+	sum := &dto.Summary{}
+	qs := make([]*dto.Quantile, 0, len(s.objectives))
+
+	s.bufMtx.Lock()
+	s.mtx.Lock()
+	// Swap bufs even if hotBuf is empty to set new hotBufExpTime.
+	s.swapBufs(time.Now())
+	s.bufMtx.Unlock()
+
+	s.flushColdBuf()
+	sum.SampleCount = proto.Uint64(s.cnt)
+	sum.SampleSum = proto.Float64(s.sum)
+
+	for _, rank := range s.sortedObjectives {
+		var q float64
+		if s.headStream.Count() == 0 {
+			q = math.NaN()
+		} else {
+			q = s.headStream.Query(rank)
+		}
+		qs = append(qs, &dto.Quantile{
+			Quantile: proto.Float64(rank),
+			Value:    proto.Float64(q),
+		})
+	}
+
+	s.mtx.Unlock()
+
+	if len(qs) > 0 {
+		sort.Sort(quantSort(qs))
+	}
+	sum.Quantile = qs
+
+	out.Summary = sum
+	out.Label = s.labelPairs
+	return nil
+}
+
+func (s *summary) newStream() *quantile.Stream {
+	return quantile.NewTargeted(s.objectives)
+}
+
+// asyncFlush needs bufMtx locked.
+func (s *summary) asyncFlush(now time.Time) {
+	s.mtx.Lock()
+	s.swapBufs(now)
+
+	// Unblock the original goroutine that was responsible for the mutation
+	// that triggered the compaction.  But hold onto the global non-buffer
+	// state mutex until the operation finishes.
+	go func() {
+		s.flushColdBuf()
+		s.mtx.Unlock()
+	}()
+}
+
+// rotateStreams needs mtx AND bufMtx locked.
+func (s *summary) maybeRotateStreams() {
+	for !s.hotBufExpTime.Equal(s.headStreamExpTime) {
+		s.headStream.Reset()
+		s.headStreamIdx++
+		if s.headStreamIdx >= len(s.streams) {
+			s.headStreamIdx = 0
+		}
+		s.headStream = s.streams[s.headStreamIdx]
+		s.headStreamExpTime = s.headStreamExpTime.Add(s.streamDuration)
+	}
+}
+
+// flushColdBuf needs mtx locked.
+func (s *summary) flushColdBuf() {
+	for _, v := range s.coldBuf {
+		for _, stream := range s.streams {
+			stream.Insert(v)
+		}
+		s.cnt++
+		s.sum += v
+	}
+	s.coldBuf = s.coldBuf[0:0]
+	s.maybeRotateStreams()
+}
+
+// swapBufs needs mtx AND bufMtx locked, coldBuf must be empty.
+func (s *summary) swapBufs(now time.Time) {
+	if len(s.coldBuf) != 0 {
+		panic("coldBuf is not empty")
+	}
+	s.hotBuf, s.coldBuf = s.coldBuf, s.hotBuf
+	// hotBuf is now empty and gets new expiration set.
+	for now.After(s.hotBufExpTime) {
+		s.hotBufExpTime = s.hotBufExpTime.Add(s.streamDuration)
+	}
+}
+
+type quantSort []*dto.Quantile
+
+func (s quantSort) Len() int {
+	return len(s)
+}
+
+func (s quantSort) Swap(i, j int) {
+	s[i], s[j] = s[j], s[i]
+}
+
+func (s quantSort) Less(i, j int) bool {
+	return s[i].GetQuantile() < s[j].GetQuantile()
+}
+
+// SummaryVec is a Collector that bundles a set of Summaries that all share the
+// same Desc, but have different values for their variable labels. This is used
+// if you want to count the same thing partitioned by various dimensions
+// (e.g. HTTP request latencies, partitioned by status code and method). Create
+// instances with NewSummaryVec.
+type SummaryVec struct {
+	*metricVec
+}
+
+// NewSummaryVec creates a new SummaryVec based on the provided SummaryOpts and
+// partitioned by the given label names.
+func NewSummaryVec(opts SummaryOpts, labelNames []string) *SummaryVec {
+	desc := NewDesc(
+		BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
+		opts.Help,
+		labelNames,
+		opts.ConstLabels,
+	)
+	return &SummaryVec{
+		metricVec: newMetricVec(desc, func(lvs ...string) Metric {
+			return newSummary(desc, opts, lvs...)
+		}),
+	}
+}
+
+// GetMetricWithLabelValues returns the Summary for the given slice of label
+// values (same order as the VariableLabels in Desc). If that combination of
+// label values is accessed for the first time, a new Summary is created.
+//
+// It is possible to call this method without using the returned Summary to only
+// create the new Summary but leave it at its starting value, a Summary without
+// any observations.
+//
+// Keeping the Summary for later use is possible (and should be considered if
+// performance is critical), but keep in mind that Reset, DeleteLabelValues and
+// Delete can be used to delete the Summary from the SummaryVec. In that case, the
+// Summary will still exist, but it will not be exported anymore, even if a
+// Summary with the same label values is created later. See also the CounterVec
+// example.
+//
+// An error is returned if the number of label values is not the same as the
+// number of VariableLabels in Desc.
+//
+// Note that for more than one label value, this method is prone to mistakes
+// caused by an incorrect order of arguments. Consider GetMetricWith(Labels) as
+// an alternative to avoid that type of mistake. For higher label numbers, the
+// latter has a much more readable (albeit more verbose) syntax, but it comes
+// with a performance overhead (for creating and processing the Labels map).
+// See also the GaugeVec example.
+func (m *SummaryVec) GetMetricWithLabelValues(lvs ...string) (Observer, error) {
+	metric, err := m.metricVec.getMetricWithLabelValues(lvs...)
+	if metric != nil {
+		return metric.(Observer), err
+	}
+	return nil, err
+}
+
+// GetMetricWith returns the Summary for the given Labels map (the label names
+// must match those of the VariableLabels in Desc). If that label map is
+// accessed for the first time, a new Summary is created. Implications of
+// creating a Summary without using it and keeping the Summary for later use are
+// the same as for GetMetricWithLabelValues.
+//
+// An error is returned if the number and names of the Labels are inconsistent
+// with those of the VariableLabels in Desc.
+//
+// This method is used for the same purpose as
+// GetMetricWithLabelValues(...string). See there for pros and cons of the two
+// methods.
+func (m *SummaryVec) GetMetricWith(labels Labels) (Observer, error) {
+	metric, err := m.metricVec.getMetricWith(labels)
+	if metric != nil {
+		return metric.(Observer), err
+	}
+	return nil, err
+}
+
+// WithLabelValues works as GetMetricWithLabelValues, but panics where
+// GetMetricWithLabelValues would have returned an error. By not returning an
+// error, WithLabelValues allows shortcuts like
+//     myVec.WithLabelValues("404", "GET").Observe(42.21)
+func (m *SummaryVec) WithLabelValues(lvs ...string) Observer {
+	return m.metricVec.withLabelValues(lvs...).(Observer)
+}
+
+// With works as GetMetricWith, but panics where GetMetricWithLabels would have
+// returned an error. By not returning an error, With allows shortcuts like
+//     myVec.With(Labels{"code": "404", "method": "GET"}).Observe(42.21)
+func (m *SummaryVec) With(labels Labels) Observer {
+	return m.metricVec.with(labels).(Observer)
+}
+
+type constSummary struct {
+	desc       *Desc
+	count      uint64
+	sum        float64
+	quantiles  map[float64]float64
+	labelPairs []*dto.LabelPair
+}
+
+func (s *constSummary) Desc() *Desc {
+	return s.desc
+}
+
+func (s *constSummary) Write(out *dto.Metric) error {
+	sum := &dto.Summary{}
+	qs := make([]*dto.Quantile, 0, len(s.quantiles))
+
+	sum.SampleCount = proto.Uint64(s.count)
+	sum.SampleSum = proto.Float64(s.sum)
+
+	for rank, q := range s.quantiles {
+		qs = append(qs, &dto.Quantile{
+			Quantile: proto.Float64(rank),
+			Value:    proto.Float64(q),
+		})
+	}
+
+	if len(qs) > 0 {
+		sort.Sort(quantSort(qs))
+	}
+	sum.Quantile = qs
+
+	out.Summary = sum
+	out.Label = s.labelPairs
+
+	return nil
+}
+
+// NewConstSummary returns a metric representing a Prometheus summary with fixed
+// values for the count, sum, and quantiles. As those parameters cannot be
+// changed, the returned value does not implement the Summary interface (but
+// only the Metric interface). Users of this package will not have much use for
+// it in regular operations. However, when implementing custom Collectors, it is
+// useful as a throw-away metric that is generated on the fly to send it to
+// Prometheus in the Collect method.
+//
+// quantiles maps ranks to quantile values. For example, a median latency of
+// 0.23s and a 99th percentile latency of 0.56s would be expressed as:
+//     map[float64]float64{0.5: 0.23, 0.99: 0.56}
+//
+// NewConstSummary returns an error if the length of labelValues is not
+// consistent with the variable labels in Desc.
+func NewConstSummary(
+	desc *Desc,
+	count uint64,
+	sum float64,
+	quantiles map[float64]float64,
+	labelValues ...string,
+) (Metric, error) {
+	if err := validateLabelValues(labelValues, len(desc.variableLabels)); err != nil {
+		return nil, err
+	}
+	return &constSummary{
+		desc:       desc,
+		count:      count,
+		sum:        sum,
+		quantiles:  quantiles,
+		labelPairs: makeLabelPairs(desc, labelValues),
+	}, nil
+}
+
+// MustNewConstSummary is a version of NewConstSummary that panics where
+// NewConstMetric would have returned an error.
+func MustNewConstSummary(
+	desc *Desc,
+	count uint64,
+	sum float64,
+	quantiles map[float64]float64,
+	labelValues ...string,
+) Metric {
+	m, err := NewConstSummary(desc, count, sum, quantiles, labelValues...)
+	if err != nil {
+		panic(err)
+	}
+	return m
+}

vendor/github.com/prometheus/client_golang/prometheus/summary_test.go

@@ -0,0 +1,388 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+import (
+	"math"
+	"math/rand"
+	"sort"
+	"sync"
+	"testing"
+	"testing/quick"
+	"time"
+
+	dto "github.com/prometheus/client_model/go"
+)
+
+func TestSummaryWithDefaultObjectives(t *testing.T) {
+	reg := NewRegistry()
+	summaryWithDefaultObjectives := NewSummary(SummaryOpts{
+		Name: "default_objectives",
+		Help: "Test help.",
+	})
+	if err := reg.Register(summaryWithDefaultObjectives); err != nil {
+		t.Error(err)
+	}
+
+	m := &dto.Metric{}
+	if err := summaryWithDefaultObjectives.Write(m); err != nil {
+		t.Error(err)
+	}
+	if len(m.GetSummary().Quantile) != len(DefObjectives) {
+		t.Error("expected default objectives in summary")
+	}
+}
+
+func TestSummaryWithoutObjectives(t *testing.T) {
+	reg := NewRegistry()
+	summaryWithEmptyObjectives := NewSummary(SummaryOpts{
+		Name:       "empty_objectives",
+		Help:       "Test help.",
+		Objectives: map[float64]float64{},
+	})
+	if err := reg.Register(summaryWithEmptyObjectives); err != nil {
+		t.Error(err)
+	}
+
+	m := &dto.Metric{}
+	if err := summaryWithEmptyObjectives.Write(m); err != nil {
+		t.Error(err)
+	}
+	if len(m.GetSummary().Quantile) != 0 {
+		t.Error("expected no objectives in summary")
+	}
+}
+
+func benchmarkSummaryObserve(w int, b *testing.B) {
+	b.StopTimer()
+
+	wg := new(sync.WaitGroup)
+	wg.Add(w)
+
+	g := new(sync.WaitGroup)
+	g.Add(1)
+
+	s := NewSummary(SummaryOpts{})
+
+	for i := 0; i < w; i++ {
+		go func() {
+			g.Wait()
+
+			for i := 0; i < b.N; i++ {
+				s.Observe(float64(i))
+			}
+
+			wg.Done()
+		}()
+	}
+
+	b.StartTimer()
+	g.Done()
+	wg.Wait()
+}
+
+func BenchmarkSummaryObserve1(b *testing.B) {
+	benchmarkSummaryObserve(1, b)
+}
+
+func BenchmarkSummaryObserve2(b *testing.B) {
+	benchmarkSummaryObserve(2, b)
+}
+
+func BenchmarkSummaryObserve4(b *testing.B) {
+	benchmarkSummaryObserve(4, b)
+}
+
+func BenchmarkSummaryObserve8(b *testing.B) {
+	benchmarkSummaryObserve(8, b)
+}
+
+func benchmarkSummaryWrite(w int, b *testing.B) {
+	b.StopTimer()
+
+	wg := new(sync.WaitGroup)
+	wg.Add(w)
+
+	g := new(sync.WaitGroup)
+	g.Add(1)
+
+	s := NewSummary(SummaryOpts{})
+
+	for i := 0; i < 1000000; i++ {
+		s.Observe(float64(i))
+	}
+
+	for j := 0; j < w; j++ {
+		outs := make([]dto.Metric, b.N)
+
+		go func(o []dto.Metric) {
+			g.Wait()
+
+			for i := 0; i < b.N; i++ {
+				s.Write(&o[i])
+			}
+
+			wg.Done()
+		}(outs)
+	}
+
+	b.StartTimer()
+	g.Done()
+	wg.Wait()
+}
+
+func BenchmarkSummaryWrite1(b *testing.B) {
+	benchmarkSummaryWrite(1, b)
+}
+
+func BenchmarkSummaryWrite2(b *testing.B) {
+	benchmarkSummaryWrite(2, b)
+}
+
+func BenchmarkSummaryWrite4(b *testing.B) {
+	benchmarkSummaryWrite(4, b)
+}
+
+func BenchmarkSummaryWrite8(b *testing.B) {
+	benchmarkSummaryWrite(8, b)
+}
+
+func TestSummaryConcurrency(t *testing.T) {
+	if testing.Short() {
+		t.Skip("Skipping test in short mode.")
+	}
+
+	rand.Seed(42)
+
+	it := func(n uint32) bool {
+		mutations := int(n%1e4 + 1e4)
+		concLevel := int(n%5 + 1)
+		total := mutations * concLevel
+
+		var start, end sync.WaitGroup
+		start.Add(1)
+		end.Add(concLevel)
+
+		sum := NewSummary(SummaryOpts{
+			Name:       "test_summary",
+			Help:       "helpless",
+			Objectives: map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001},
+		})
+
+		allVars := make([]float64, total)
+		var sampleSum float64
+		for i := 0; i < concLevel; i++ {
+			vals := make([]float64, mutations)
+			for j := 0; j < mutations; j++ {
+				v := rand.NormFloat64()
+				vals[j] = v
+				allVars[i*mutations+j] = v
+				sampleSum += v
+			}
+
+			go func(vals []float64) {
+				start.Wait()
+				for _, v := range vals {
+					sum.Observe(v)
+				}
+				end.Done()
+			}(vals)
+		}
+		sort.Float64s(allVars)
+		start.Done()
+		end.Wait()
+
+		m := &dto.Metric{}
+		sum.Write(m)
+		if got, want := int(*m.Summary.SampleCount), total; got != want {
+			t.Errorf("got sample count %d, want %d", got, want)
+		}
+		if got, want := *m.Summary.SampleSum, sampleSum; math.Abs((got-want)/want) > 0.001 {
+			t.Errorf("got sample sum %f, want %f", got, want)
+		}
+
+		objectives := make([]float64, 0, len(DefObjectives))
+		for qu := range DefObjectives {
+			objectives = append(objectives, qu)
+		}
+		sort.Float64s(objectives)
+
+		for i, wantQ := range objectives {
+			ε := DefObjectives[wantQ]
+			gotQ := *m.Summary.Quantile[i].Quantile
+			gotV := *m.Summary.Quantile[i].Value
+			min, max := getBounds(allVars, wantQ, ε)
+			if gotQ != wantQ {
+				t.Errorf("got quantile %f, want %f", gotQ, wantQ)
+			}
+			if gotV < min || gotV > max {
+				t.Errorf("got %f for quantile %f, want [%f,%f]", gotV, gotQ, min, max)
+			}
+		}
+		return true
+	}
+
+	if err := quick.Check(it, nil); err != nil {
+		t.Error(err)
+	}
+}
+
+func TestSummaryVecConcurrency(t *testing.T) {
+	if testing.Short() {
+		t.Skip("Skipping test in short mode.")
+	}
+
+	rand.Seed(42)
+
+	objectives := make([]float64, 0, len(DefObjectives))
+	for qu := range DefObjectives {
+
+		objectives = append(objectives, qu)
+	}
+	sort.Float64s(objectives)
+
+	it := func(n uint32) bool {
+		mutations := int(n%1e4 + 1e4)
+		concLevel := int(n%7 + 1)
+		vecLength := int(n%3 + 1)
+
+		var start, end sync.WaitGroup
+		start.Add(1)
+		end.Add(concLevel)
+
+		sum := NewSummaryVec(
+			SummaryOpts{
+				Name:       "test_summary",
+				Help:       "helpless",
+				Objectives: map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001},
+			},
+			[]string{"label"},
+		)
+
+		allVars := make([][]float64, vecLength)
+		sampleSums := make([]float64, vecLength)
+		for i := 0; i < concLevel; i++ {
+			vals := make([]float64, mutations)
+			picks := make([]int, mutations)
+			for j := 0; j < mutations; j++ {
+				v := rand.NormFloat64()
+				vals[j] = v
+				pick := rand.Intn(vecLength)
+				picks[j] = pick
+				allVars[pick] = append(allVars[pick], v)
+				sampleSums[pick] += v
+			}
+
+			go func(vals []float64) {
+				start.Wait()
+				for i, v := range vals {
+					sum.WithLabelValues(string('A' + picks[i])).Observe(v)
+				}
+				end.Done()
+			}(vals)
+		}
+		for _, vars := range allVars {
+			sort.Float64s(vars)
+		}
+		start.Done()
+		end.Wait()
+
+		for i := 0; i < vecLength; i++ {
+			m := &dto.Metric{}
+			s := sum.WithLabelValues(string('A' + i))
+			s.(Summary).Write(m)
+			if got, want := int(*m.Summary.SampleCount), len(allVars[i]); got != want {
+				t.Errorf("got sample count %d for label %c, want %d", got, 'A'+i, want)
+			}
+			if got, want := *m.Summary.SampleSum, sampleSums[i]; math.Abs((got-want)/want) > 0.001 {
+				t.Errorf("got sample sum %f for label %c, want %f", got, 'A'+i, want)
+			}
+			for j, wantQ := range objectives {
+				ε := DefObjectives[wantQ]
+				gotQ := *m.Summary.Quantile[j].Quantile
+				gotV := *m.Summary.Quantile[j].Value
+				min, max := getBounds(allVars[i], wantQ, ε)
+				if gotQ != wantQ {
+					t.Errorf("got quantile %f for label %c, want %f", gotQ, 'A'+i, wantQ)
+				}
+				if gotV < min || gotV > max {
+					t.Errorf("got %f for quantile %f for label %c, want [%f,%f]", gotV, gotQ, 'A'+i, min, max)
+				}
+			}
+		}
+		return true
+	}
+
+	if err := quick.Check(it, nil); err != nil {
+		t.Error(err)
+	}
+}
+
+func TestSummaryDecay(t *testing.T) {
+	if testing.Short() {
+		t.Skip("Skipping test in short mode.")
+		// More because it depends on timing than because it is particularly long...
+	}
+
+	sum := NewSummary(SummaryOpts{
+		Name:       "test_summary",
+		Help:       "helpless",
+		MaxAge:     100 * time.Millisecond,
+		Objectives: map[float64]float64{0.1: 0.001},
+		AgeBuckets: 10,
+	})
+
+	m := &dto.Metric{}
+	i := 0
+	tick := time.NewTicker(time.Millisecond)
+	for range tick.C {
+		i++
+		sum.Observe(float64(i))
+		if i%10 == 0 {
+			sum.Write(m)
+			if got, want := *m.Summary.Quantile[0].Value, math.Max(float64(i)/10, float64(i-90)); math.Abs(got-want) > 20 {
+				t.Errorf("%d. got %f, want %f", i, got, want)
+			}
+			m.Reset()
+		}
+		if i >= 1000 {
+			break
+		}
+	}
+	tick.Stop()
+	// Wait for MaxAge without observations and make sure quantiles are NaN.
+	time.Sleep(100 * time.Millisecond)
+	sum.Write(m)
+	if got := *m.Summary.Quantile[0].Value; !math.IsNaN(got) {
+		t.Errorf("got %f, want NaN after expiration", got)
+	}
+}
+
+func getBounds(vars []float64, q, ε float64) (min, max float64) {
+	// TODO(beorn7): This currently tolerates an error of up to 2*ε. The
+	// error must be at most ε, but for some reason, it's sometimes slightly
+	// higher. That's a bug.
+	n := float64(len(vars))
+	lower := int((q - 2*ε) * n)
+	upper := int(math.Ceil((q + 2*ε) * n))
+	min = vars[0]
+	if lower > 1 {
+		min = vars[lower-1]
+	}
+	max = vars[len(vars)-1]
+	if upper < len(vars) {
+		max = vars[upper-1]
+	}
+	return
+}

vendor/github.com/prometheus/client_golang/prometheus/timer.go

@@ -0,0 +1,51 @@
+// Copyright 2016 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+import "time"
+
+// Timer is a helper type to time functions. Use NewTimer to create new
+// instances.
+type Timer struct {
+	begin    time.Time
+	observer Observer
+}
+
+// NewTimer creates a new Timer. The provided Observer is used to observe a
+// duration in seconds. Timer is usually used to time a function call in the
+// following way:
+//    func TimeMe() {
+//        timer := NewTimer(myHistogram)
+//        defer timer.ObserveDuration()
+//        // Do actual work.
+//    }
+func NewTimer(o Observer) *Timer {
+	return &Timer{
+		begin:    time.Now(),
+		observer: o,
+	}
+}
+
+// ObserveDuration records the duration passed since the Timer was created with
+// NewTimer. It calls the Observe method of the Observer provided during
+// construction with the duration in seconds as an argument. ObserveDuration is
+// usually called with a defer statement.
+//
+// Note that this method is only guaranteed to never observe negative durations
+// if used with Go1.9+.
+func (t *Timer) ObserveDuration() {
+	if t.observer != nil {
+		t.observer.Observe(time.Since(t.begin).Seconds())
+	}
+}

vendor/github.com/prometheus/client_golang/prometheus/timer_test.go

@@ -0,0 +1,152 @@
+// Copyright 2016 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+import (
+	"testing"
+
+	dto "github.com/prometheus/client_model/go"
+)
+
+func TestTimerObserve(t *testing.T) {
+	var (
+		his   = NewHistogram(HistogramOpts{Name: "test_histogram"})
+		sum   = NewSummary(SummaryOpts{Name: "test_summary"})
+		gauge = NewGauge(GaugeOpts{Name: "test_gauge"})
+	)
+
+	func() {
+		hisTimer := NewTimer(his)
+		sumTimer := NewTimer(sum)
+		gaugeTimer := NewTimer(ObserverFunc(gauge.Set))
+		defer hisTimer.ObserveDuration()
+		defer sumTimer.ObserveDuration()
+		defer gaugeTimer.ObserveDuration()
+	}()
+
+	m := &dto.Metric{}
+	his.Write(m)
+	if want, got := uint64(1), m.GetHistogram().GetSampleCount(); want != got {
+		t.Errorf("want %d observations for histogram, got %d", want, got)
+	}
+	m.Reset()
+	sum.Write(m)
+	if want, got := uint64(1), m.GetSummary().GetSampleCount(); want != got {
+		t.Errorf("want %d observations for summary, got %d", want, got)
+	}
+	m.Reset()
+	gauge.Write(m)
+	if got := m.GetGauge().GetValue(); got <= 0 {
+		t.Errorf("want value > 0 for gauge, got %f", got)
+	}
+}
+
+func TestTimerEmpty(t *testing.T) {
+	emptyTimer := NewTimer(nil)
+	emptyTimer.ObserveDuration()
+	// Do nothing, just demonstrate it works without panic.
+}
+
+func TestTimerConditionalTiming(t *testing.T) {
+	var (
+		his = NewHistogram(HistogramOpts{
+			Name: "test_histogram",
+		})
+		timeMe = true
+		m      = &dto.Metric{}
+	)
+
+	timedFunc := func() {
+		timer := NewTimer(ObserverFunc(func(v float64) {
+			if timeMe {
+				his.Observe(v)
+			}
+		}))
+		defer timer.ObserveDuration()
+	}
+
+	timedFunc() // This will time.
+	his.Write(m)
+	if want, got := uint64(1), m.GetHistogram().GetSampleCount(); want != got {
+		t.Errorf("want %d observations for histogram, got %d", want, got)
+	}
+
+	timeMe = false
+	timedFunc() // This will not time again.
+	m.Reset()
+	his.Write(m)
+	if want, got := uint64(1), m.GetHistogram().GetSampleCount(); want != got {
+		t.Errorf("want %d observations for histogram, got %d", want, got)
+	}
+}
+
+func TestTimerByOutcome(t *testing.T) {
+	var (
+		his = NewHistogramVec(
+			HistogramOpts{Name: "test_histogram"},
+			[]string{"outcome"},
+		)
+		outcome = "foo"
+		m       = &dto.Metric{}
+	)
+
+	timedFunc := func() {
+		timer := NewTimer(ObserverFunc(func(v float64) {
+			his.WithLabelValues(outcome).Observe(v)
+		}))
+		defer timer.ObserveDuration()
+
+		if outcome == "foo" {
+			outcome = "bar"
+			return
+		}
+		outcome = "foo"
+	}
+
+	timedFunc()
+	his.WithLabelValues("foo").(Histogram).Write(m)
+	if want, got := uint64(0), m.GetHistogram().GetSampleCount(); want != got {
+		t.Errorf("want %d observations for 'foo' histogram, got %d", want, got)
+	}
+	m.Reset()
+	his.WithLabelValues("bar").(Histogram).Write(m)
+	if want, got := uint64(1), m.GetHistogram().GetSampleCount(); want != got {
+		t.Errorf("want %d observations for 'bar' histogram, got %d", want, got)
+	}
+
+	timedFunc()
+	m.Reset()
+	his.WithLabelValues("foo").(Histogram).Write(m)
+	if want, got := uint64(1), m.GetHistogram().GetSampleCount(); want != got {
+		t.Errorf("want %d observations for 'foo' histogram, got %d", want, got)
+	}
+	m.Reset()
+	his.WithLabelValues("bar").(Histogram).Write(m)
+	if want, got := uint64(1), m.GetHistogram().GetSampleCount(); want != got {
+		t.Errorf("want %d observations for 'bar' histogram, got %d", want, got)
+	}
+
+	timedFunc()
+	m.Reset()
+	his.WithLabelValues("foo").(Histogram).Write(m)
+	if want, got := uint64(1), m.GetHistogram().GetSampleCount(); want != got {
+		t.Errorf("want %d observations for 'foo' histogram, got %d", want, got)
+	}
+	m.Reset()
+	his.WithLabelValues("bar").(Histogram).Write(m)
+	if want, got := uint64(2), m.GetHistogram().GetSampleCount(); want != got {
+		t.Errorf("want %d observations for 'bar' histogram, got %d", want, got)
+	}
+
+}

vendor/github.com/prometheus/client_golang/prometheus/untyped.go

@@ -0,0 +1,42 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+// UntypedOpts is an alias for Opts. See there for doc comments.
+type UntypedOpts Opts
+
+// UntypedFunc works like GaugeFunc but the collected metric is of type
+// "Untyped". UntypedFunc is useful to mirror an external metric of unknown
+// type.
+//
+// To create UntypedFunc instances, use NewUntypedFunc.
+type UntypedFunc interface {
+	Metric
+	Collector
+}
+
+// NewUntypedFunc creates a new UntypedFunc based on the provided
+// UntypedOpts. The value reported is determined by calling the given function
+// from within the Write method. Take into account that metric collection may
+// happen concurrently. If that results in concurrent calls to Write, like in
+// the case where an UntypedFunc is directly registered with Prometheus, the
+// provided function must be concurrency-safe.
+func NewUntypedFunc(opts UntypedOpts, function func() float64) UntypedFunc {
+	return newValueFunc(NewDesc(
+		BuildFQName(opts.Namespace, opts.Subsystem, opts.Name),
+		opts.Help,
+		nil,
+		opts.ConstLabels,
+	), UntypedValue, function)
+}

vendor/github.com/prometheus/client_golang/prometheus/value.go

@@ -0,0 +1,236 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+import (
+	"fmt"
+	"math"
+	"sort"
+	"sync/atomic"
+	"time"
+
+	dto "github.com/prometheus/client_model/go"
+
+	"github.com/golang/protobuf/proto"
+)
+
+// ValueType is an enumeration of metric types that represent a simple value.
+type ValueType int
+
+// Possible values for the ValueType enum.
+const (
+	_ ValueType = iota
+	CounterValue
+	GaugeValue
+	UntypedValue
+)
+
+// value is a generic metric for simple values. It implements Metric, Collector,
+// Counter, Gauge, and Untyped. Its effective type is determined by
+// ValueType. This is a low-level building block used by the library to back the
+// implementations of Counter, Gauge, and Untyped.
+type value struct {
+	// valBits contains the bits of the represented float64 value. It has
+	// to go first in the struct to guarantee alignment for atomic
+	// operations.  http://golang.org/pkg/sync/atomic/#pkg-note-BUG
+	valBits uint64
+
+	selfCollector
+
+	desc       *Desc
+	valType    ValueType
+	labelPairs []*dto.LabelPair
+}
+
+// newValue returns a newly allocated value with the given Desc, ValueType,
+// sample value and label values. It panics if the number of label
+// values is different from the number of variable labels in Desc.
+func newValue(desc *Desc, valueType ValueType, val float64, labelValues ...string) *value {
+	if len(labelValues) != len(desc.variableLabels) {
+		panic(errInconsistentCardinality)
+	}
+	result := &value{
+		desc:       desc,
+		valType:    valueType,
+		valBits:    math.Float64bits(val),
+		labelPairs: makeLabelPairs(desc, labelValues),
+	}
+	result.init(result)
+	return result
+}
+
+func (v *value) Desc() *Desc {
+	return v.desc
+}
+
+func (v *value) Set(val float64) {
+	atomic.StoreUint64(&v.valBits, math.Float64bits(val))
+}
+
+func (v *value) SetToCurrentTime() {
+	v.Set(float64(time.Now().UnixNano()) / 1e9)
+}
+
+func (v *value) Inc() {
+	v.Add(1)
+}
+
+func (v *value) Dec() {
+	v.Add(-1)
+}
+
+func (v *value) Add(val float64) {
+	for {
+		oldBits := atomic.LoadUint64(&v.valBits)
+		newBits := math.Float64bits(math.Float64frombits(oldBits) + val)
+		if atomic.CompareAndSwapUint64(&v.valBits, oldBits, newBits) {
+			return
+		}
+	}
+}
+
+func (v *value) Sub(val float64) {
+	v.Add(val * -1)
+}
+
+func (v *value) Write(out *dto.Metric) error {
+	val := math.Float64frombits(atomic.LoadUint64(&v.valBits))
+	return populateMetric(v.valType, val, v.labelPairs, out)
+}
+
+// valueFunc is a generic metric for simple values retrieved on collect time
+// from a function. It implements Metric and Collector. Its effective type is
+// determined by ValueType. This is a low-level building block used by the
+// library to back the implementations of CounterFunc, GaugeFunc, and
+// UntypedFunc.
+type valueFunc struct {
+	selfCollector
+
+	desc       *Desc
+	valType    ValueType
+	function   func() float64
+	labelPairs []*dto.LabelPair
+}
+
+// newValueFunc returns a newly allocated valueFunc with the given Desc and
+// ValueType. The value reported is determined by calling the given function
+// from within the Write method. Take into account that metric collection may
+// happen concurrently. If that results in concurrent calls to Write, like in
+// the case where a valueFunc is directly registered with Prometheus, the
+// provided function must be concurrency-safe.
+func newValueFunc(desc *Desc, valueType ValueType, function func() float64) *valueFunc {
+	result := &valueFunc{
+		desc:       desc,
+		valType:    valueType,
+		function:   function,
+		labelPairs: makeLabelPairs(desc, nil),
+	}
+	result.init(result)
+	return result
+}
+
+func (v *valueFunc) Desc() *Desc {
+	return v.desc
+}
+
+func (v *valueFunc) Write(out *dto.Metric) error {
+	return populateMetric(v.valType, v.function(), v.labelPairs, out)
+}
+
+// NewConstMetric returns a metric with one fixed value that cannot be
+// changed. Users of this package will not have much use for it in regular
+// operations. However, when implementing custom Collectors, it is useful as a
+// throw-away metric that is generated on the fly to send it to Prometheus in
+// the Collect method. NewConstMetric returns an error if the length of
+// labelValues is not consistent with the variable labels in Desc.
+func NewConstMetric(desc *Desc, valueType ValueType, value float64, labelValues ...string) (Metric, error) {
+	if err := validateLabelValues(labelValues, len(desc.variableLabels)); err != nil {
+		return nil, err
+	}
+	return &constMetric{
+		desc:       desc,
+		valType:    valueType,
+		val:        value,
+		labelPairs: makeLabelPairs(desc, labelValues),
+	}, nil
+}
+
+// MustNewConstMetric is a version of NewConstMetric that panics where
+// NewConstMetric would have returned an error.
+func MustNewConstMetric(desc *Desc, valueType ValueType, value float64, labelValues ...string) Metric {
+	m, err := NewConstMetric(desc, valueType, value, labelValues...)
+	if err != nil {
+		panic(err)
+	}
+	return m
+}
+
+type constMetric struct {
+	desc       *Desc
+	valType    ValueType
+	val        float64
+	labelPairs []*dto.LabelPair
+}
+
+func (m *constMetric) Desc() *Desc {
+	return m.desc
+}
+
+func (m *constMetric) Write(out *dto.Metric) error {
+	return populateMetric(m.valType, m.val, m.labelPairs, out)
+}
+
+func populateMetric(
+	t ValueType,
+	v float64,
+	labelPairs []*dto.LabelPair,
+	m *dto.Metric,
+) error {
+	m.Label = labelPairs
+	switch t {
+	case CounterValue:
+		m.Counter = &dto.Counter{Value: proto.Float64(v)}
+	case GaugeValue:
+		m.Gauge = &dto.Gauge{Value: proto.Float64(v)}
+	case UntypedValue:
+		m.Untyped = &dto.Untyped{Value: proto.Float64(v)}
+	default:
+		return fmt.Errorf("encountered unknown type %v", t)
+	}
+	return nil
+}
+
+func makeLabelPairs(desc *Desc, labelValues []string) []*dto.LabelPair {
+	totalLen := len(desc.variableLabels) + len(desc.constLabelPairs)
+	if totalLen == 0 {
+		// Super fast path.
+		return nil
+	}
+	if len(desc.variableLabels) == 0 {
+		// Moderately fast path.
+		return desc.constLabelPairs
+	}
+	labelPairs := make([]*dto.LabelPair, 0, totalLen)
+	for i, n := range desc.variableLabels {
+		labelPairs = append(labelPairs, &dto.LabelPair{
+			Name:  proto.String(n),
+			Value: proto.String(labelValues[i]),
+		})
+	}
+	for _, lp := range desc.constLabelPairs {
+		labelPairs = append(labelPairs, lp)
+	}
+	sort.Sort(LabelPairSorter(labelPairs))
+	return labelPairs
+}

vendor/github.com/prometheus/client_golang/prometheus/value_test.go

@@ -0,0 +1,43 @@
+package prometheus
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestNewConstMetricInvalidLabelValues(t *testing.T) {
+	testCases := []struct {
+		desc   string
+		labels Labels
+	}{
+		{
+			desc:   "non utf8 label value",
+			labels: Labels{"a": "\xFF"},
+		},
+		{
+			desc:   "not enough label values",
+			labels: Labels{},
+		},
+		{
+			desc:   "too many label values",
+			labels: Labels{"a": "1", "b": "2"},
+		},
+	}
+
+	for _, test := range testCases {
+		metricDesc := NewDesc(
+			"sample_value",
+			"sample value",
+			[]string{"a"},
+			Labels{},
+		)
+
+		expectPanic(t, func() {
+			MustNewConstMetric(metricDesc, CounterValue, 0.3, "\xFF")
+		}, fmt.Sprintf("WithLabelValues: expected panic because: %s", test.desc))
+
+		if _, err := NewConstMetric(metricDesc, CounterValue, 0.3, "\xFF"); err == nil {
+			t.Errorf("NewConstMetric: expected error because: %s", test.desc)
+		}
+	}
+}

vendor/github.com/prometheus/client_golang/prometheus/vec.go

@@ -0,0 +1,363 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+import (
+	"fmt"
+	"sync"
+
+	"github.com/prometheus/common/model"
+)
+
+// metricVec is a Collector to bundle metrics of the same name that differ in
+// their label values. metricVec is not used directly (and therefore
+// unexported). It is used as a building block for implementations of vectors of
+// a given metric type, like GaugeVec, CounterVec, SummaryVec, HistogramVec, and
+// UntypedVec.
+type metricVec struct {
+	mtx      sync.RWMutex // Protects the children.
+	children map[uint64][]metricWithLabelValues
+	desc     *Desc
+
+	newMetric   func(labelValues ...string) Metric
+	hashAdd     func(h uint64, s string) uint64 // replace hash function for testing collision handling
+	hashAddByte func(h uint64, b byte) uint64
+}
+
+// newMetricVec returns an initialized metricVec.
+func newMetricVec(desc *Desc, newMetric func(lvs ...string) Metric) *metricVec {
+	return &metricVec{
+		children:    map[uint64][]metricWithLabelValues{},
+		desc:        desc,
+		newMetric:   newMetric,
+		hashAdd:     hashAdd,
+		hashAddByte: hashAddByte,
+	}
+}
+
+// metricWithLabelValues provides the metric and its label values for
+// disambiguation on hash collision.
+type metricWithLabelValues struct {
+	values []string
+	metric Metric
+}
+
+// Describe implements Collector. The length of the returned slice
+// is always one.
+func (m *metricVec) Describe(ch chan<- *Desc) {
+	ch <- m.desc
+}
+
+// Collect implements Collector.
+func (m *metricVec) Collect(ch chan<- Metric) {
+	m.mtx.RLock()
+	defer m.mtx.RUnlock()
+
+	for _, metrics := range m.children {
+		for _, metric := range metrics {
+			ch <- metric.metric
+		}
+	}
+}
+
+func (m *metricVec) getMetricWithLabelValues(lvs ...string) (Metric, error) {
+	h, err := m.hashLabelValues(lvs)
+	if err != nil {
+		return nil, err
+	}
+
+	return m.getOrCreateMetricWithLabelValues(h, lvs), nil
+}
+
+func (m *metricVec) getMetricWith(labels Labels) (Metric, error) {
+	h, err := m.hashLabels(labels)
+	if err != nil {
+		return nil, err
+	}
+
+	return m.getOrCreateMetricWithLabels(h, labels), nil
+}
+
+func (m *metricVec) withLabelValues(lvs ...string) Metric {
+	metric, err := m.getMetricWithLabelValues(lvs...)
+	if err != nil {
+		panic(err)
+	}
+	return metric
+}
+
+func (m *metricVec) with(labels Labels) Metric {
+	metric, err := m.getMetricWith(labels)
+	if err != nil {
+		panic(err)
+	}
+	return metric
+}
+
+// DeleteLabelValues removes the metric where the variable labels are the same
+// as those passed in as labels (same order as the VariableLabels in Desc). It
+// returns true if a metric was deleted.
+//
+// It is not an error if the number of label values is not the same as the
+// number of VariableLabels in Desc. However, such inconsistent label count can
+// never match an actual metric, so the method will always return false in that
+// case.
+//
+// Note that for more than one label value, this method is prone to mistakes
+// caused by an incorrect order of arguments. Consider Delete(Labels) as an
+// alternative to avoid that type of mistake. For higher label numbers, the
+// latter has a much more readable (albeit more verbose) syntax, but it comes
+// with a performance overhead (for creating and processing the Labels map).
+// See also the CounterVec example.
+func (m *metricVec) DeleteLabelValues(lvs ...string) bool {
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
+
+	h, err := m.hashLabelValues(lvs)
+	if err != nil {
+		return false
+	}
+	return m.deleteByHashWithLabelValues(h, lvs)
+}
+
+// Delete deletes the metric where the variable labels are the same as those
+// passed in as labels. It returns true if a metric was deleted.
+//
+// It is not an error if the number and names of the Labels are inconsistent
+// with those of the VariableLabels in Desc. However, such inconsistent Labels
+// can never match an actual metric, so the method will always return false in
+// that case.
+//
+// This method is used for the same purpose as DeleteLabelValues(...string). See
+// there for pros and cons of the two methods.
+func (m *metricVec) Delete(labels Labels) bool {
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
+
+	h, err := m.hashLabels(labels)
+	if err != nil {
+		return false
+	}
+
+	return m.deleteByHashWithLabels(h, labels)
+}
+
+// deleteByHashWithLabelValues removes the metric from the hash bucket h. If
+// there are multiple matches in the bucket, use lvs to select a metric and
+// remove only that metric.
+func (m *metricVec) deleteByHashWithLabelValues(h uint64, lvs []string) bool {
+	metrics, ok := m.children[h]
+	if !ok {
+		return false
+	}
+
+	i := m.findMetricWithLabelValues(metrics, lvs)
+	if i >= len(metrics) {
+		return false
+	}
+
+	if len(metrics) > 1 {
+		m.children[h] = append(metrics[:i], metrics[i+1:]...)
+	} else {
+		delete(m.children, h)
+	}
+	return true
+}
+
+// deleteByHashWithLabels removes the metric from the hash bucket h. If there
+// are multiple matches in the bucket, use lvs to select a metric and remove
+// only that metric.
+func (m *metricVec) deleteByHashWithLabels(h uint64, labels Labels) bool {
+	metrics, ok := m.children[h]
+	if !ok {
+		return false
+	}
+	i := m.findMetricWithLabels(metrics, labels)
+	if i >= len(metrics) {
+		return false
+	}
+
+	if len(metrics) > 1 {
+		m.children[h] = append(metrics[:i], metrics[i+1:]...)
+	} else {
+		delete(m.children, h)
+	}
+	return true
+}
+
+// Reset deletes all metrics in this vector.
+func (m *metricVec) Reset() {
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
+
+	for h := range m.children {
+		delete(m.children, h)
+	}
+}
+
+func (m *metricVec) hashLabelValues(vals []string) (uint64, error) {
+	if err := validateLabelValues(vals, len(m.desc.variableLabels)); err != nil {
+		return 0, err
+	}
+
+	h := hashNew()
+	for _, val := range vals {
+		h = m.hashAdd(h, val)
+		h = m.hashAddByte(h, model.SeparatorByte)
+	}
+	return h, nil
+}
+
+func (m *metricVec) hashLabels(labels Labels) (uint64, error) {
+	if err := validateValuesInLabels(labels, len(m.desc.variableLabels)); err != nil {
+		return 0, err
+	}
+
+	h := hashNew()
+	for _, label := range m.desc.variableLabels {
+		val, ok := labels[label]
+		if !ok {
+			return 0, fmt.Errorf("label name %q missing in label map", label)
+		}
+		h = m.hashAdd(h, val)
+		h = m.hashAddByte(h, model.SeparatorByte)
+	}
+	return h, nil
+}
+
+// getOrCreateMetricWithLabelValues retrieves the metric by hash and label value
+// or creates it and returns the new one.
+//
+// This function holds the mutex.
+func (m *metricVec) getOrCreateMetricWithLabelValues(hash uint64, lvs []string) Metric {
+	m.mtx.RLock()
+	metric, ok := m.getMetricWithHashAndLabelValues(hash, lvs)
+	m.mtx.RUnlock()
+	if ok {
+		return metric
+	}
+
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
+	metric, ok = m.getMetricWithHashAndLabelValues(hash, lvs)
+	if !ok {
+		// Copy to avoid allocation in case wo don't go down this code path.
+		copiedLVs := make([]string, len(lvs))
+		copy(copiedLVs, lvs)
+		metric = m.newMetric(copiedLVs...)
+		m.children[hash] = append(m.children[hash], metricWithLabelValues{values: copiedLVs, metric: metric})
+	}
+	return metric
+}
+
+// getOrCreateMetricWithLabelValues retrieves the metric by hash and label value
+// or creates it and returns the new one.
+//
+// This function holds the mutex.
+func (m *metricVec) getOrCreateMetricWithLabels(hash uint64, labels Labels) Metric {
+	m.mtx.RLock()
+	metric, ok := m.getMetricWithHashAndLabels(hash, labels)
+	m.mtx.RUnlock()
+	if ok {
+		return metric
+	}
+
+	m.mtx.Lock()
+	defer m.mtx.Unlock()
+	metric, ok = m.getMetricWithHashAndLabels(hash, labels)
+	if !ok {
+		lvs := m.extractLabelValues(labels)
+		metric = m.newMetric(lvs...)
+		m.children[hash] = append(m.children[hash], metricWithLabelValues{values: lvs, metric: metric})
+	}
+	return metric
+}
+
+// getMetricWithHashAndLabelValues gets a metric while handling possible
+// collisions in the hash space. Must be called while holding the read mutex.
+func (m *metricVec) getMetricWithHashAndLabelValues(h uint64, lvs []string) (Metric, bool) {
+	metrics, ok := m.children[h]
+	if ok {
+		if i := m.findMetricWithLabelValues(metrics, lvs); i < len(metrics) {
+			return metrics[i].metric, true
+		}
+	}
+	return nil, false
+}
+
+// getMetricWithHashAndLabels gets a metric while handling possible collisions in
+// the hash space. Must be called while holding read mutex.
+func (m *metricVec) getMetricWithHashAndLabels(h uint64, labels Labels) (Metric, bool) {
+	metrics, ok := m.children[h]
+	if ok {
+		if i := m.findMetricWithLabels(metrics, labels); i < len(metrics) {
+			return metrics[i].metric, true
+		}
+	}
+	return nil, false
+}
+
+// findMetricWithLabelValues returns the index of the matching metric or
+// len(metrics) if not found.
+func (m *metricVec) findMetricWithLabelValues(metrics []metricWithLabelValues, lvs []string) int {
+	for i, metric := range metrics {
+		if m.matchLabelValues(metric.values, lvs) {
+			return i
+		}
+	}
+	return len(metrics)
+}
+
+// findMetricWithLabels returns the index of the matching metric or len(metrics)
+// if not found.
+func (m *metricVec) findMetricWithLabels(metrics []metricWithLabelValues, labels Labels) int {
+	for i, metric := range metrics {
+		if m.matchLabels(metric.values, labels) {
+			return i
+		}
+	}
+	return len(metrics)
+}
+
+func (m *metricVec) matchLabelValues(values []string, lvs []string) bool {
+	if len(values) != len(lvs) {
+		return false
+	}
+	for i, v := range values {
+		if v != lvs[i] {
+			return false
+		}
+	}
+	return true
+}
+
+func (m *metricVec) matchLabels(values []string, labels Labels) bool {
+	if len(labels) != len(values) {
+		return false
+	}
+	for i, k := range m.desc.variableLabels {
+		if values[i] != labels[k] {
+			return false
+		}
+	}
+	return true
+}
+
+func (m *metricVec) extractLabelValues(labels Labels) []string {
+	labelValues := make([]string, len(labels))
+	for i, k := range m.desc.variableLabels {
+		labelValues[i] = labels[k]
+	}
+	return labelValues
+}

vendor/github.com/prometheus/client_golang/prometheus/vec_test.go

@@ -0,0 +1,312 @@
+// Copyright 2014 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package prometheus
+
+import (
+	"fmt"
+	"testing"
+
+	dto "github.com/prometheus/client_model/go"
+)
+
+func TestDelete(t *testing.T) {
+	vec := NewGaugeVec(
+		GaugeOpts{
+			Name: "test",
+			Help: "helpless",
+		},
+		[]string{"l1", "l2"},
+	)
+	testDelete(t, vec)
+}
+
+func TestDeleteWithCollisions(t *testing.T) {
+	vec := NewGaugeVec(
+		GaugeOpts{
+			Name: "test",
+			Help: "helpless",
+		},
+		[]string{"l1", "l2"},
+	)
+	vec.hashAdd = func(h uint64, s string) uint64 { return 1 }
+	vec.hashAddByte = func(h uint64, b byte) uint64 { return 1 }
+	testDelete(t, vec)
+}
+
+func testDelete(t *testing.T, vec *GaugeVec) {
+	if got, want := vec.Delete(Labels{"l1": "v1", "l2": "v2"}), false; got != want {
+		t.Errorf("got %v, want %v", got, want)
+	}
+
+	vec.With(Labels{"l1": "v1", "l2": "v2"}).(Gauge).Set(42)
+	if got, want := vec.Delete(Labels{"l1": "v1", "l2": "v2"}), true; got != want {
+		t.Errorf("got %v, want %v", got, want)
+	}
+	if got, want := vec.Delete(Labels{"l1": "v1", "l2": "v2"}), false; got != want {
+		t.Errorf("got %v, want %v", got, want)
+	}
+
+	vec.With(Labels{"l1": "v1", "l2": "v2"}).(Gauge).Set(42)
+	if got, want := vec.Delete(Labels{"l2": "v2", "l1": "v1"}), true; got != want {
+		t.Errorf("got %v, want %v", got, want)
+	}
+	if got, want := vec.Delete(Labels{"l2": "v2", "l1": "v1"}), false; got != want {
+		t.Errorf("got %v, want %v", got, want)
+	}
+
+	vec.With(Labels{"l1": "v1", "l2": "v2"}).(Gauge).Set(42)
+	if got, want := vec.Delete(Labels{"l2": "v1", "l1": "v2"}), false; got != want {
+		t.Errorf("got %v, want %v", got, want)
+	}
+	if got, want := vec.Delete(Labels{"l1": "v1"}), false; got != want {
+		t.Errorf("got %v, want %v", got, want)
+	}
+}
+
+func TestDeleteLabelValues(t *testing.T) {
+	vec := NewGaugeVec(
+		GaugeOpts{
+			Name: "test",
+			Help: "helpless",
+		},
+		[]string{"l1", "l2"},
+	)
+	testDeleteLabelValues(t, vec)
+}
+
+func TestDeleteLabelValuesWithCollisions(t *testing.T) {
+	vec := NewGaugeVec(
+		GaugeOpts{
+			Name: "test",
+			Help: "helpless",
+		},
+		[]string{"l1", "l2"},
+	)
+	vec.hashAdd = func(h uint64, s string) uint64 { return 1 }
+	vec.hashAddByte = func(h uint64, b byte) uint64 { return 1 }
+	testDeleteLabelValues(t, vec)
+}
+
+func testDeleteLabelValues(t *testing.T, vec *GaugeVec) {
+	if got, want := vec.DeleteLabelValues("v1", "v2"), false; got != want {
+		t.Errorf("got %v, want %v", got, want)
+	}
+
+	vec.With(Labels{"l1": "v1", "l2": "v2"}).(Gauge).Set(42)
+	vec.With(Labels{"l1": "v1", "l2": "v3"}).(Gauge).Set(42) // Add junk data for collision.
+	if got, want := vec.DeleteLabelValues("v1", "v2"), true; got != want {
+		t.Errorf("got %v, want %v", got, want)
+	}
+	if got, want := vec.DeleteLabelValues("v1", "v2"), false; got != want {
+		t.Errorf("got %v, want %v", got, want)
+	}
+	if got, want := vec.DeleteLabelValues("v1", "v3"), true; got != want {
+		t.Errorf("got %v, want %v", got, want)
+	}
+
+	vec.With(Labels{"l1": "v1", "l2": "v2"}).(Gauge).Set(42)
+	// Delete out of order.
+	if got, want := vec.DeleteLabelValues("v2", "v1"), false; got != want {
+		t.Errorf("got %v, want %v", got, want)
+	}
+	if got, want := vec.DeleteLabelValues("v1"), false; got != want {
+		t.Errorf("got %v, want %v", got, want)
+	}
+}
+
+func TestMetricVec(t *testing.T) {
+	vec := NewGaugeVec(
+		GaugeOpts{
+			Name: "test",
+			Help: "helpless",
+		},
+		[]string{"l1", "l2"},
+	)
+	testMetricVec(t, vec)
+}
+
+func TestMetricVecWithCollisions(t *testing.T) {
+	vec := NewGaugeVec(
+		GaugeOpts{
+			Name: "test",
+			Help: "helpless",
+		},
+		[]string{"l1", "l2"},
+	)
+	vec.hashAdd = func(h uint64, s string) uint64 { return 1 }
+	vec.hashAddByte = func(h uint64, b byte) uint64 { return 1 }
+	testMetricVec(t, vec)
+}
+
+func testMetricVec(t *testing.T, vec *GaugeVec) {
+	vec.Reset() // Actually test Reset now!
+
+	var pair [2]string
+	// Keep track of metrics.
+	expected := map[[2]string]int{}
+
+	for i := 0; i < 1000; i++ {
+		pair[0], pair[1] = fmt.Sprint(i%4), fmt.Sprint(i%5) // Varying combinations multiples.
+		expected[pair]++
+		vec.WithLabelValues(pair[0], pair[1]).Inc()
+
+		expected[[2]string{"v1", "v2"}]++
+		vec.WithLabelValues("v1", "v2").(Gauge).Inc()
+	}
+
+	var total int
+	for _, metrics := range vec.children {
+		for _, metric := range metrics {
+			total++
+			copy(pair[:], metric.values)
+
+			var metricOut dto.Metric
+			if err := metric.metric.Write(&metricOut); err != nil {
+				t.Fatal(err)
+			}
+			actual := *metricOut.Gauge.Value
+
+			var actualPair [2]string
+			for i, label := range metricOut.Label {
+				actualPair[i] = *label.Value
+			}
+
+			// Test output pair against metric.values to ensure we've selected
+			// the right one. We check this to ensure the below check means
+			// anything at all.
+			if actualPair != pair {
+				t.Fatalf("unexpected pair association in metric map: %v != %v", actualPair, pair)
+			}
+
+			if actual != float64(expected[pair]) {
+				t.Fatalf("incorrect counter value for %v: %v != %v", pair, actual, expected[pair])
+			}
+		}
+	}
+
+	if total != len(expected) {
+		t.Fatalf("unexpected number of metrics: %v != %v", total, len(expected))
+	}
+
+	vec.Reset()
+
+	if len(vec.children) > 0 {
+		t.Fatalf("reset failed")
+	}
+}
+
+func TestCounterVecEndToEndWithCollision(t *testing.T) {
+	vec := NewCounterVec(
+		CounterOpts{
+			Name: "test",
+			Help: "helpless",
+		},
+		[]string{"labelname"},
+	)
+	vec.WithLabelValues("77kepQFQ8Kl").Inc()
+	vec.WithLabelValues("!0IC=VloaY").Add(2)
+
+	m := &dto.Metric{}
+	if err := vec.WithLabelValues("77kepQFQ8Kl").Write(m); err != nil {
+		t.Fatal(err)
+	}
+	if got, want := m.GetLabel()[0].GetValue(), "77kepQFQ8Kl"; got != want {
+		t.Errorf("got label value %q, want %q", got, want)
+	}
+	if got, want := m.GetCounter().GetValue(), 1.; got != want {
+		t.Errorf("got value %f, want %f", got, want)
+	}
+	m.Reset()
+	if err := vec.WithLabelValues("!0IC=VloaY").Write(m); err != nil {
+		t.Fatal(err)
+	}
+	if got, want := m.GetLabel()[0].GetValue(), "!0IC=VloaY"; got != want {
+		t.Errorf("got label value %q, want %q", got, want)
+	}
+	if got, want := m.GetCounter().GetValue(), 2.; got != want {
+		t.Errorf("got value %f, want %f", got, want)
+	}
+}
+
+func BenchmarkMetricVecWithLabelValuesBasic(b *testing.B) {
+	benchmarkMetricVecWithLabelValues(b, map[string][]string{
+		"l1": {"onevalue"},
+		"l2": {"twovalue"},
+	})
+}
+
+func BenchmarkMetricVecWithLabelValues2Keys10ValueCardinality(b *testing.B) {
+	benchmarkMetricVecWithLabelValuesCardinality(b, 2, 10)
+}
+
+func BenchmarkMetricVecWithLabelValues4Keys10ValueCardinality(b *testing.B) {
+	benchmarkMetricVecWithLabelValuesCardinality(b, 4, 10)
+}
+
+func BenchmarkMetricVecWithLabelValues2Keys100ValueCardinality(b *testing.B) {
+	benchmarkMetricVecWithLabelValuesCardinality(b, 2, 100)
+}
+
+func BenchmarkMetricVecWithLabelValues10Keys100ValueCardinality(b *testing.B) {
+	benchmarkMetricVecWithLabelValuesCardinality(b, 10, 100)
+}
+
+func BenchmarkMetricVecWithLabelValues10Keys1000ValueCardinality(b *testing.B) {
+	benchmarkMetricVecWithLabelValuesCardinality(b, 10, 1000)
+}
+
+func benchmarkMetricVecWithLabelValuesCardinality(b *testing.B, nkeys, nvalues int) {
+	labels := map[string][]string{}
+
+	for i := 0; i < nkeys; i++ {
+		var (
+			k  = fmt.Sprintf("key-%v", i)
+			vs = make([]string, 0, nvalues)
+		)
+		for j := 0; j < nvalues; j++ {
+			vs = append(vs, fmt.Sprintf("value-%v", j))
+		}
+		labels[k] = vs
+	}
+
+	benchmarkMetricVecWithLabelValues(b, labels)
+}
+
+func benchmarkMetricVecWithLabelValues(b *testing.B, labels map[string][]string) {
+	var keys []string
+	for k := range labels { // Map order dependent, who cares though.
+		keys = append(keys, k)
+	}
+
+	values := make([]string, len(labels)) // Value cache for permutations.
+	vec := NewGaugeVec(
+		GaugeOpts{
+			Name: "test",
+			Help: "helpless",
+		},
+		keys,
+	)
+
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		// Varies input across provide map entries based on key size.
+		for j, k := range keys {
+			candidates := labels[k]
+			values[j] = candidates[i%len(candidates)]
+		}
+
+		vec.WithLabelValues(values...)
+	}
+}