mirror of https://github.com/knative/pkg.git
58 lines
1.8 KiB
Go
58 lines
1.8 KiB
Go
/*
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Copyright 2018 The Knative Authors
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package logging
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import (
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"context"
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"go.uber.org/zap"
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)
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type loggerKey struct{}
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// This logger is used when there is no logger attached to the context.
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// Rather than returning nil and causing a panic, we will use the fallback
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// logger. Fallback logger is tagged with logger=fallback to make sure
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// that code that doesn't set the logger correctly can be caught at runtime.
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var fallbackLogger *zap.SugaredLogger
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func init() {
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if logger, err := zap.NewProduction(); err != nil {
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// We failed to create a fallback logger. Our fallback
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// unfortunately falls back to noop.
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fallbackLogger = zap.NewNop().Sugar()
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} else {
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fallbackLogger = logger.Named("fallback").Sugar()
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}
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}
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// WithLogger returns a copy of parent context in which the
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// value associated with logger key is the supplied logger.
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func WithLogger(ctx context.Context, logger *zap.SugaredLogger) context.Context {
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return context.WithValue(ctx, loggerKey{}, logger)
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}
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// FromContext returns the logger stored in context.
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// Returns nil if no logger is set in context, or if the stored value is
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// not of correct type.
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func FromContext(ctx context.Context) *zap.SugaredLogger {
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if logger, ok := ctx.Value(loggerKey{}).(*zap.SugaredLogger); ok {
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return logger
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}
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return fallbackLogger
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}
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