global.go

Documentation: go.uber.org/zap

     1  // Copyright (c) 2016 Uber Technologies, Inc.
     2  //
     3  // Permission is hereby granted, free of charge, to any person obtaining a copy
     4  // of this software and associated documentation files (the "Software"), to deal
     5  // in the Software without restriction, including without limitation the rights
     6  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     7  // copies of the Software, and to permit persons to whom the Software is
     8  // furnished to do so, subject to the following conditions:
     9  //
    10  // The above copyright notice and this permission notice shall be included in
    11  // all copies or substantial portions of the Software.
    12  //
    13  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    14  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    15  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    16  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    17  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    18  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    19  // THE SOFTWARE.
    20  
    21  package zap
    22  
    23  import (
    24  	"bytes"
    25  	"fmt"
    26  	"log"
    27  	"os"
    28  	"sync"
    29  
    30  	"go.uber.org/zap/zapcore"
    31  )
    32  
    33  const (
    34  	_stdLogDefaultDepth      = 1
    35  	_loggerWriterDepth       = 2
    36  	_programmerErrorTemplate = "You've found a bug in zap! Please file a bug at " +
    37  		"https://github.com/uber-go/zap/issues/new and reference this error: %v"
    38  )
    39  
    40  var (
    41  	_globalMu sync.RWMutex
    42  	_globalL  = NewNop()
    43  	_globalS  = _globalL.Sugar()
    44  )
    45  
    46  // L returns the global Logger, which can be reconfigured with ReplaceGlobals.
    47  // It's safe for concurrent use.
    48  func L() *Logger {
    49  	_globalMu.RLock()
    50  	l := _globalL
    51  	_globalMu.RUnlock()
    52  	return l
    53  }
    54  
    55  // S returns the global SugaredLogger, which can be reconfigured with
    56  // ReplaceGlobals. It's safe for concurrent use.
    57  func S() *SugaredLogger {
    58  	_globalMu.RLock()
    59  	s := _globalS
    60  	_globalMu.RUnlock()
    61  	return s
    62  }
    63  
    64  // ReplaceGlobals replaces the global Logger and SugaredLogger, and returns a
    65  // function to restore the original values. It's safe for concurrent use.
    66  func ReplaceGlobals(logger *Logger) func() {
    67  	_globalMu.Lock()
    68  	prev := _globalL
    69  	_globalL = logger
    70  	_globalS = logger.Sugar()
    71  	_globalMu.Unlock()
    72  	return func() { ReplaceGlobals(prev) }
    73  }
    74  
    75  // NewStdLog returns a *log.Logger which writes to the supplied zap Logger at
    76  // InfoLevel. To redirect the standard library's package-global logging
    77  // functions, use RedirectStdLog instead.
    78  func NewStdLog(l *Logger) *log.Logger {
    79  	logger := l.WithOptions(AddCallerSkip(_stdLogDefaultDepth + _loggerWriterDepth))
    80  	f := logger.Info
    81  	return log.New(&loggerWriter{f}, "" /* prefix */, 0 /* flags */)
    82  }
    83  
    84  // NewStdLogAt returns *log.Logger which writes to supplied zap logger at
    85  // required level.
    86  func NewStdLogAt(l *Logger, level zapcore.Level) (*log.Logger, error) {
    87  	logger := l.WithOptions(AddCallerSkip(_stdLogDefaultDepth + _loggerWriterDepth))
    88  	logFunc, err := levelToFunc(logger, level)
    89  	if err != nil {
    90  		return nil, err
    91  	}
    92  	return log.New(&loggerWriter{logFunc}, "" /* prefix */, 0 /* flags */), nil
    93  }
    94  
    95  // RedirectStdLog redirects output from the standard library's package-global
    96  // logger to the supplied logger at InfoLevel. Since zap already handles caller
    97  // annotations, timestamps, etc., it automatically disables the standard
    98  // library's annotations and prefixing.
    99  //
   100  // It returns a function to restore the original prefix and flags and reset the
   101  // standard library's output to os.Stderr.
   102  func RedirectStdLog(l *Logger) func() {
   103  	f, err := redirectStdLogAt(l, InfoLevel)
   104  	if err != nil {
   105  		// Can't get here, since passing InfoLevel to redirectStdLogAt always
   106  		// works.
   107  		panic(fmt.Sprintf(_programmerErrorTemplate, err))
   108  	}
   109  	return f
   110  }
   111  
   112  // RedirectStdLogAt redirects output from the standard library's package-global
   113  // logger to the supplied logger at the specified level. Since zap already
   114  // handles caller annotations, timestamps, etc., it automatically disables the
   115  // standard library's annotations and prefixing.
   116  //
   117  // It returns a function to restore the original prefix and flags and reset the
   118  // standard library's output to os.Stderr.
   119  func RedirectStdLogAt(l *Logger, level zapcore.Level) (func(), error) {
   120  	return redirectStdLogAt(l, level)
   121  }
   122  
   123  func redirectStdLogAt(l *Logger, level zapcore.Level) (func(), error) {
   124  	flags := log.Flags()
   125  	prefix := log.Prefix()
   126  	log.SetFlags(0)
   127  	log.SetPrefix("")
   128  	logger := l.WithOptions(AddCallerSkip(_stdLogDefaultDepth + _loggerWriterDepth))
   129  	logFunc, err := levelToFunc(logger, level)
   130  	if err != nil {
   131  		return nil, err
   132  	}
   133  	log.SetOutput(&loggerWriter{logFunc})
   134  	return func() {
   135  		log.SetFlags(flags)
   136  		log.SetPrefix(prefix)
   137  		log.SetOutput(os.Stderr)
   138  	}, nil
   139  }
   140  
   141  func levelToFunc(logger *Logger, lvl zapcore.Level) (func(string, ...Field), error) {
   142  	switch lvl {
   143  	case DebugLevel:
   144  		return logger.Debug, nil
   145  	case InfoLevel:
   146  		return logger.Info, nil
   147  	case WarnLevel:
   148  		return logger.Warn, nil
   149  	case ErrorLevel:
   150  		return logger.Error, nil
   151  	case DPanicLevel:
   152  		return logger.DPanic, nil
   153  	case PanicLevel:
   154  		return logger.Panic, nil
   155  	case FatalLevel:
   156  		return logger.Fatal, nil
   157  	}
   158  	return nil, fmt.Errorf("unrecognized level: %q", lvl)
   159  }
   160  
   161  type loggerWriter struct {
   162  	logFunc func(msg string, fields ...Field)
   163  }
   164  
   165  func (l *loggerWriter) Write(p []byte) (int, error) {
   166  	p = bytes.TrimSpace(p)
   167  	l.logFunc(string(p))
   168  	return len(p), nil
   169  }
   170
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