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This moves the global logger into a separate file together with the functions that implement contextual logging.
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| /* | ||
| Copyright 2021 The Kubernetes 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. | ||
| */ | ||
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| package klog | ||
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| import ( | ||
| "context" | ||
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| "github.com/go-logr/logr" | ||
| ) | ||
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| // This file provides the implementation of | ||
| // https://github.com/kubernetes/enhancements/tree/master/keps/sig-instrumentation/1602-structured-logging | ||
| // | ||
| // SetLogger and ClearLogger were originally added to klog.go and got moved | ||
| // here. Contextual logging adds a way to retrieve a Logger for direct logging | ||
| // without the logging calls in klog.go. | ||
| // | ||
| // The global variables are expected to be modified only during sequential | ||
| // parts of a program (init, serial tests) and therefore are not protected by | ||
| // mutex locking. | ||
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| var ( | ||
| // contextualLoggingEnabled controls whether contextual logging is | ||
| // active. Disabling it may have some small performance benefit. | ||
| contextualLoggingEnabled = true | ||
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| // globalLogger is the global Logger chosen by users of klog, nil if | ||
| // none is available. | ||
| globalLogger *Logger | ||
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| // contextualLogger defines whether globalLogger may get called | ||
| // directly. | ||
| contextualLogger bool | ||
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| // klogLogger is used as fallback for logging through the normal klog code | ||
| // when no Logger is set. | ||
| klogLogger logr.Logger = logr.New(&klogger{}) | ||
| ) | ||
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| // SetLogger sets a Logger implementation that will be used as backing | ||
| // implementation of the traditional klog log calls. klog will do its own | ||
| // verbosity checks before calling logger.V().Info. logger.Error is always | ||
| // called, regardless of the klog verbosity settings. | ||
| // | ||
| // If set, all log lines will be suppressed from the regular Output, and | ||
| // redirected to the logr implementation. | ||
| // Use as: | ||
| // ... | ||
| // klog.SetLogger(zapr.NewLogger(zapLog)) | ||
| // | ||
| // To remove a backing logr implemention, use ClearLogger. Setting an | ||
| // empty logger with SetLogger(logr.Logger{}) does not work. | ||
| // | ||
| // Modifying the logger is not thread-safe and should be done while no other | ||
| // goroutines invoke log calls, usually during program initialization. | ||
| func SetLogger(logger logr.Logger) { | ||
| globalLogger = &logger | ||
| contextualLogger = false | ||
| } | ||
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| // SetContextualLogger does the same as SetLogger, but in addition the | ||
| // logger may also get called directly by code that retrieves it | ||
| // with FromContext, TODO or Background. The logger therefore must | ||
| // implements its own verbosity checking. | ||
| func SetContextualLogger(logger logr.Logger) { | ||
| globalLogger = &logger | ||
| contextualLogger = true | ||
| } | ||
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| // ClearLogger removes a backing Logger implementation if one was set earlier | ||
| // with SetLogger. | ||
| // | ||
| // Modifying the logger is not thread-safe and should be done while no other | ||
| // goroutines invoke log calls, usually during program initialization. | ||
| func ClearLogger() { | ||
| globalLogger = nil | ||
| } | ||
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| // EnableContextualLogging controls whether contextual logging is enabled. | ||
| // By default it is enabled. When disabled, FromContext avoids looking up | ||
| // the logger in the context and always returns the global logger. | ||
| // LoggerWithValues, LoggerWithName, and NewContext become no-ops | ||
| // and return their input logger respectively context. This may be useful | ||
| // to avoid the additional overhead for contextual logging. | ||
| // | ||
| // This must be called during initialization before goroutines are started. | ||
| // | ||
| // Experimental | ||
| // | ||
| // Notice: This function is EXPERIMENTAL and may be changed or removed in a | ||
| // later release. | ||
| func EnableContextualLogging(enabled bool) { | ||
| contextualLoggingEnabled = enabled | ||
| } | ||
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| // FromContext retrieves a logger set by the caller or, if not set, | ||
| // falls back to the program's global logger (a Logger instance or klog | ||
| // itself). | ||
| // | ||
| // Experimental | ||
| // | ||
| // Notice: This function is EXPERIMENTAL and may be changed or removed in a | ||
| // later release. | ||
| func FromContext(ctx context.Context) Logger { | ||
| if contextualLoggingEnabled { | ||
| if logger, err := logr.FromContext(ctx); err == nil { | ||
| return logger | ||
| } | ||
| } | ||
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| return Background() | ||
| } | ||
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| // TODO can be used as a last resort by code that has no means of | ||
| // receiving a logger from its caller. FromContext or an explicit logger | ||
| // parameter should be used instead. | ||
| // | ||
| // Experimental | ||
| // | ||
| // Notice: This function is EXPERIMENTAL and may be changed or removed in a | ||
| // later release. | ||
| func TODO() Logger { | ||
| return Background() | ||
| } | ||
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| // Background retrieves the fallback logger. It should not be called before | ||
| // that logger was initialized by the program and not by code that should | ||
| // better receive a logger via its parameters. TODO can be used as a temporary | ||
| // solution for such code. | ||
| // | ||
| // Experimental | ||
| // | ||
| // Notice: This function is EXPERIMENTAL and may be changed or removed in a | ||
| // later release. | ||
| func Background() Logger { | ||
| if globalLogger != nil && contextualLogger { | ||
| return *globalLogger | ||
| } | ||
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| return klogLogger | ||
| } | ||
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| // LoggerWithValues returns logger.WithValues(...kv) when | ||
| // contextual logging is enabled, otherwise the logger. | ||
| // | ||
| // Experimental | ||
| // | ||
| // Notice: This function is EXPERIMENTAL and may be changed or removed in a | ||
| // later release. | ||
| func LoggerWithValues(logger Logger, kv ...interface{}) Logger { | ||
| if contextualLoggingEnabled { | ||
| return logger.WithValues(kv...) | ||
| } | ||
| return logger | ||
| } | ||
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| // LoggerWithName returns logger.WithName(name) when contextual logging is | ||
| // enabled, otherwise the logger. | ||
| // | ||
| // Experimental | ||
| // | ||
| // Notice: This function is EXPERIMENTAL and may be changed or removed in a | ||
| // later release. | ||
| func LoggerWithName(logger Logger, name string) Logger { | ||
| if contextualLoggingEnabled { | ||
| return logger.WithName(name) | ||
| } | ||
| return logger | ||
| } | ||
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| // NewContext returns logr.NewContext(ctx, logger) when | ||
| // contextual logging is enabled, otherwise ctx. | ||
| // | ||
| // Experimental | ||
| // | ||
| // Notice: This function is EXPERIMENTAL and may be changed or removed in a | ||
| // later release. | ||
| func NewContext(ctx context.Context, logger Logger) context.Context { | ||
| if contextualLoggingEnabled { | ||
| return logr.NewContext(ctx, logger) | ||
| } | ||
| return ctx | ||
| } |
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