TUN-5989: Add in-memory otlp exporter

vendor/go.opentelemetry.io/otel/handler.go

@@ -0,0 +1,98 @@
+// 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 otel // import "go.opentelemetry.io/otel"
+
+import (
+	"log"
+	"os"
+	"sync"
+)
+
+var (
+	// globalErrorHandler provides an ErrorHandler that can be used
+	// throughout an OpenTelemetry instrumented project. When a user
+	// specified ErrorHandler is registered (`SetErrorHandler`) all calls to
+	// `Handle` and will be delegated to the registered ErrorHandler.
+	globalErrorHandler = defaultErrorHandler()
+
+	// Compile-time check that delegator implements ErrorHandler.
+	_ ErrorHandler = (*delegator)(nil)
+	// Compile-time check that errLogger implements ErrorHandler.
+	_ ErrorHandler = (*errLogger)(nil)
+)
+
+type delegator struct {
+	lock *sync.RWMutex
+	eh   ErrorHandler
+}
+
+func (d *delegator) Handle(err error) {
+	d.lock.RLock()
+	defer d.lock.RUnlock()
+	d.eh.Handle(err)
+}
+
+// setDelegate sets the ErrorHandler delegate.
+func (d *delegator) setDelegate(eh ErrorHandler) {
+	d.lock.Lock()
+	defer d.lock.Unlock()
+	d.eh = eh
+}
+
+func defaultErrorHandler() *delegator {
+	return &delegator{
+		lock: &sync.RWMutex{},
+		eh:   &errLogger{l: log.New(os.Stderr, "", log.LstdFlags)},
+	}
+
+}
+
+// errLogger logs errors if no delegate is set, otherwise they are delegated.
+type errLogger struct {
+	l *log.Logger
+}
+
+// Handle logs err if no delegate is set, otherwise it is delegated.
+func (h *errLogger) Handle(err error) {
+	h.l.Print(err)
+}
+
+// GetErrorHandler returns the global ErrorHandler instance.
+//
+// The default ErrorHandler instance returned will log all errors to STDERR
+// until an override ErrorHandler is set with SetErrorHandler. All
+// ErrorHandler returned prior to this will automatically forward errors to
+// the set instance instead of logging.
+//
+// Subsequent calls to SetErrorHandler after the first will not forward errors
+// to the new ErrorHandler for prior returned instances.
+func GetErrorHandler() ErrorHandler {
+	return globalErrorHandler
+}
+
+// SetErrorHandler sets the global ErrorHandler to h.
+//
+// The first time this is called all ErrorHandler previously returned from
+// GetErrorHandler will send errors to h instead of the default logging
+// ErrorHandler. Subsequent calls will set the global ErrorHandler, but not
+// delegate errors to h.
+func SetErrorHandler(h ErrorHandler) {
+	globalErrorHandler.setDelegate(h)
+}
+
+// Handle is a convenience function for ErrorHandler().Handle(err)
+func Handle(err error) {
+	GetErrorHandler().Handle(err)
+}