TUN-5989: Add in-memory otlp exporter

vendor/go.opentelemetry.io/otel/internal/global/state.go

@@ -0,0 +1,127 @@
+// Copyright The OpenTelemetry 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 global // import "go.opentelemetry.io/otel/internal/global"
+
+import (
+	"errors"
+	"sync"
+	"sync/atomic"
+	"testing"
+
+	"go.opentelemetry.io/otel/propagation"
+	"go.opentelemetry.io/otel/trace"
+)
+
+type (
+	tracerProviderHolder struct {
+		tp trace.TracerProvider
+	}
+
+	propagatorsHolder struct {
+		tm propagation.TextMapPropagator
+	}
+)
+
+var (
+	globalTracer      = defaultTracerValue()
+	globalPropagators = defaultPropagatorsValue()
+
+	delegateTraceOnce             sync.Once
+	delegateTextMapPropagatorOnce sync.Once
+)
+
+// TracerProvider is the internal implementation for global.TracerProvider.
+func TracerProvider() trace.TracerProvider {
+	return globalTracer.Load().(tracerProviderHolder).tp
+}
+
+// SetTracerProvider is the internal implementation for global.SetTracerProvider.
+func SetTracerProvider(tp trace.TracerProvider) {
+	current := TracerProvider()
+
+	if _, cOk := current.(*tracerProvider); cOk {
+		if _, tpOk := tp.(*tracerProvider); tpOk && current == tp {
+			// Do not assign the default delegating TracerProvider to delegate
+			// to itself.
+			Error(
+				errors.New("no delegate configured in tracer provider"),
+				"Setting tracer provider to it's current value. No delegate will be configured",
+			)
+			return
+		}
+	}
+
+	delegateTraceOnce.Do(func() {
+		if def, ok := current.(*tracerProvider); ok {
+			def.setDelegate(tp)
+		}
+	})
+	globalTracer.Store(tracerProviderHolder{tp: tp})
+}
+
+// TextMapPropagator is the internal implementation for global.TextMapPropagator.
+func TextMapPropagator() propagation.TextMapPropagator {
+	return globalPropagators.Load().(propagatorsHolder).tm
+}
+
+// SetTextMapPropagator is the internal implementation for global.SetTextMapPropagator.
+func SetTextMapPropagator(p propagation.TextMapPropagator) {
+	current := TextMapPropagator()
+
+	if _, cOk := current.(*textMapPropagator); cOk {
+		if _, pOk := p.(*textMapPropagator); pOk && current == p {
+			// Do not assign the default delegating TextMapPropagator to
+			// delegate to itself.
+			Error(
+				errors.New("no delegate configured in text map propagator"),
+				"Setting text map propagator to it's current value. No delegate will be configured",
+			)
+			return
+		}
+	}
+
+	// For the textMapPropagator already returned by TextMapPropagator
+	// delegate to p.
+	delegateTextMapPropagatorOnce.Do(func() {
+		if def, ok := current.(*textMapPropagator); ok {
+			def.SetDelegate(p)
+		}
+	})
+	// Return p when subsequent calls to TextMapPropagator are made.
+	globalPropagators.Store(propagatorsHolder{tm: p})
+}
+
+func defaultTracerValue() *atomic.Value {
+	v := &atomic.Value{}
+	v.Store(tracerProviderHolder{tp: &tracerProvider{}})
+	return v
+}
+
+func defaultPropagatorsValue() *atomic.Value {
+	v := &atomic.Value{}
+	v.Store(propagatorsHolder{tm: newTextMapPropagator()})
+	return v
+}
+
+// ResetForTest configures the test to restores the initial global state during
+// its Cleanup step
+func ResetForTest(t testing.TB) {
+	t.Cleanup(func() {
+		globalTracer = defaultTracerValue()
+		globalPropagators = defaultPropagatorsValue()
+		delegateTraceOnce = sync.Once{}
+		delegateTextMapPropagatorOnce = sync.Once{}
+	})
+}