Initial QSfera import

Server/vendor/go.opentelemetry.io/otel/internal/errorhandler/errorhandler.go

@@ -0,0 +1,96 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+// Package errorhandler provides the global error handler for OpenTelemetry.
+//
+// This package has no OTel dependencies, allowing it to be imported by any
+// package in the module without creating import cycles.
+package errorhandler // import "go.opentelemetry.io/otel/internal/errorhandler"
+
+import (
+	"errors"
+	"log"
+	"sync"
+	"sync/atomic"
+)
+
+// ErrorHandler handles irremediable events.
+type ErrorHandler interface {
+	// Handle handles any error deemed irremediable by an OpenTelemetry
+	// component.
+	Handle(error)
+}
+
+type ErrDelegator struct {
+	delegate atomic.Pointer[ErrorHandler]
+}
+
+// Compile-time check that delegator implements ErrorHandler.
+var _ ErrorHandler = (*ErrDelegator)(nil)
+
+func (d *ErrDelegator) Handle(err error) {
+	if eh := d.delegate.Load(); eh != nil {
+		(*eh).Handle(err)
+		return
+	}
+	log.Print(err)
+}
+
+// setDelegate sets the ErrorHandler delegate.
+func (d *ErrDelegator) setDelegate(eh ErrorHandler) {
+	d.delegate.Store(&eh)
+}
+
+type errorHandlerHolder struct {
+	eh ErrorHandler
+}
+
+var (
+	globalErrorHandler       = defaultErrorHandler()
+	delegateErrorHandlerOnce sync.Once
+)
+
+// 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.Load().(errorHandlerHolder).eh
+}
+
+// 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) {
+	current := GetErrorHandler()
+
+	if _, cOk := current.(*ErrDelegator); cOk {
+		if _, ehOk := h.(*ErrDelegator); ehOk && current == h {
+			// Do not assign to the delegate of the default ErrDelegator to be
+			// itself.
+			log.Print(errors.New("no ErrorHandler delegate configured"), " ErrorHandler remains its current value.")
+			return
+		}
+	}
+
+	delegateErrorHandlerOnce.Do(func() {
+		if def, ok := current.(*ErrDelegator); ok {
+			def.setDelegate(h)
+		}
+	})
+	globalErrorHandler.Store(errorHandlerHolder{eh: h})
+}
+
+func defaultErrorHandler() *atomic.Value {
+	v := &atomic.Value{}
+	v.Store(errorHandlerHolder{eh: &ErrDelegator{}})
+	return v
+}