[Spike] MultiLoggerProvider

sdk/log/multi.go

@@ -0,0 +1,62 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package log // import "go.opentelemetry.io/otel/sdk/log"
+
+import (
+	"context"
+
+	"go.opentelemetry.io/otel/log"
+	"go.opentelemetry.io/otel/log/embedded"
+)
+
+type multiLoggerProvider struct {
+	embedded.LoggerProvider
+
+	providers []log.LoggerProvider
+
+	noCmp [0]func() //nolint: unused  // This is indeed used.
+}
+
+// NewMultiLoggerProvider returns a composite (fan-out) provider.
+// It duplicates its calls to all the provided providers.
+// It can be used to set up multiple processing pipelines.
+// For instance, you can have separate providers for OTel events
+// and application logs.
+func NewMultiLoggerProvider(providers ...log.LoggerProvider) log.LoggerProvider {
+	return &multiLoggerProvider{
+		providers: providers,
+	}
+}
+
+// Logger returns a logger delegating to loggers created by all providers.
+func (p *multiLoggerProvider) Logger(name string, opts ...log.LoggerOption) log.Logger {
+	var loggers []log.Logger
+	for _, p := range p.providers {
+		loggers = append(loggers, p.Logger(name, opts...))
+	}
+	return &multiLogger{loggers: loggers}
+}
+
+type multiLogger struct {
+	embedded.Logger
+
+	loggers []log.Logger
+
+	noCmp [0]func() //nolint: unused  // This is indeed used.
+}
+
+func (l *multiLogger) Emit(ctx context.Context, r log.Record) {
+	for _, l := range l.loggers {
+		l.Emit(ctx, r)
+	}
+}
+
+func (l *multiLogger) Enabled(ctx context.Context, param log.EnabledParameters) bool {
+	for _, l := range l.loggers {
+		if !l.Enabled(ctx, param) {
+			return false
+		}
+	}
+	return true
+}