gotosocial/vendor/go.opentelemetry.io/otel/handler.go
2023-05-09 18:19:48 +01:00

97 lines
3 KiB
Go

// 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/atomic"
"unsafe"
)
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 {
delegate unsafe.Pointer
}
func (d *delegator) Handle(err error) {
d.getDelegate().Handle(err)
}
func (d *delegator) getDelegate() ErrorHandler {
return *(*ErrorHandler)(atomic.LoadPointer(&d.delegate))
}
// setDelegate sets the ErrorHandler delegate.
func (d *delegator) setDelegate(eh ErrorHandler) {
atomic.StorePointer(&d.delegate, unsafe.Pointer(&eh))
}
func defaultErrorHandler() *delegator {
d := &delegator{}
d.setDelegate(&errLogger{l: log.New(os.Stderr, "", log.LstdFlags)})
return d
}
// 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)
}