Source: handler.go in package go.opentelemetry.io/otel/api/global

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 (
	"log"
	"os"
	"sync"
	"sync/atomic"

	"go.opentelemetry.io/otel"
)

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 = &loggingErrorHandler{
		l: log.New(os.Stderr, "", log.LstdFlags),
	}

delegateErrorHandlerOnce ensures that a user provided ErrorHandler is only ever registered once.

	delegateErrorHandlerOnce sync.Once

Comiple time check that loggingErrorHandler implements ErrorHandler.

	_ otel.ErrorHandler = (*loggingErrorHandler)(nil)
)

loggingErrorHandler logs all errors to STDERR.

type loggingErrorHandler struct {
	delegate atomic.Value

	l *log.Logger
}

setDelegate sets the ErrorHandler delegate if one is not already set.

func (h *loggingErrorHandler) setDelegate(d otel.ErrorHandler) {

Delegate already registered

		return
	}
	h.delegate.Store(d)
}

Handle implements otel.ErrorHandler.

func (h *loggingErrorHandler) Handle(err error) {
	if d := h.delegate.Load(); d != nil {
		d.(otel.ErrorHandler).Handle(err)
		return
	}
	h.l.Print(err)
}

ErrorHandler returns the global ErrorHandler instance. If no ErrorHandler instance has been set (`SetErrorHandler`), the default ErrorHandler which logs errors to STDERR is returned.

func ErrorHandler() otel.ErrorHandler {
	return globalErrorHandler
}

SetErrorHandler sets the global ErrorHandler to be h.

func SetErrorHandler(h otel.ErrorHandler) {
	delegateErrorHandlerOnce.Do(func() {
		current := ErrorHandler()
		if current == h {
			return
		}
		if internalHandler, ok := current.(*loggingErrorHandler); ok {
			internalHandler.setDelegate(h)
		}
	})
}

Handle is a convience function for ErrorHandler().Handle(err)

func Handle(err error) {
	ErrorHandler().Handle(err)