带你研究一下go zap的SugaredLogger！

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本文主要研究一下golang的zap的SugaredLogger

SugaredLogger

zap@v1.16.0/sugar.go

type SugaredLogger struct {     base *Logger }  func (s *SugaredLogger) Named(name string) *SugaredLogger {     return &SugaredLogger{base: s.base.Named(name)} }  func (s *SugaredLogger) With(args ...interface{}) *SugaredLogger {     return &SugaredLogger{base: s.base.With(s.sweetenFields(args)...)} }  func (s *SugaredLogger) Debug(args ...interface{}) {     s.log(DebugLevel, "", args, nil) }  func (s *SugaredLogger) Info(args ...interface{}) {     s.log(InfoLevel, "", args, nil) }  func (s *SugaredLogger) Warn(args ...interface{}) {     s.log(WarnLevel, "", args, nil) }  func (s *SugaredLogger) Error(args ...interface{}) {     s.log(ErrorLevel, "", args, nil) }  func (s *SugaredLogger) DPanic(args ...interface{}) {     s.log(DPanicLevel, "", args, nil) }  func (s *SugaredLogger) Panic(args ...interface{}) {     s.log(PanicLevel, "", args, nil) }  func (s *SugaredLogger) Fatal(args ...interface{}) {     s.log(FatalLevel, "", args, nil) }  func (s *SugaredLogger) Debugf(template string, args ...interface{}) {     s.log(DebugLevel, template, args, nil) }  func (s *SugaredLogger) Infof(template string, args ...interface{}) {     s.log(InfoLevel, template, args, nil) }  func (s *SugaredLogger) Warnf(template string, args ...interface{}) {     s.log(WarnLevel, template, args, nil) }  func (s *SugaredLogger) Errorf(template string, args ...interface{}) {     s.log(ErrorLevel, template, args, nil) }  func (s *SugaredLogger) DPanicf(template string, args ...interface{}) {     s.log(DPanicLevel, template, args, nil) }  func (s *SugaredLogger) Panicf(template string, args ...interface{}) {     s.log(PanicLevel, template, args, nil) }  func (s *SugaredLogger) Fatalf(template string, args ...interface{}) {     s.log(FatalLevel, template, args, nil) }  func (s *SugaredLogger) Debugw(msg string, keysAndValues ...interface{}) {     s.log(DebugLevel, msg, nil, keysAndValues) }  func (s *SugaredLogger) Infow(msg string, keysAndValues ...interface{}) {     s.log(InfoLevel, msg, nil, keysAndValues) }  func (s *SugaredLogger) Warnw(msg string, keysAndValues ...interface{}) {     s.log(WarnLevel, msg, nil, keysAndValues) }  func (s *SugaredLogger) Errorw(msg string, keysAndValues ...interface{}) {     s.log(ErrorLevel, msg, nil, keysAndValues) }  func (s *SugaredLogger) DPanicw(msg string, keysAndValues ...interface{}) {     s.log(DPanicLevel, msg, nil, keysAndValues) }  func (s *SugaredLogger) Panicw(msg string, keysAndValues ...interface{}) {     s.log(PanicLevel, msg, nil, keysAndValues) }  func (s *SugaredLogger) Fatalw(msg string, keysAndValues ...interface{}) {     s.log(FatalLevel, msg, nil, keysAndValues) }  func (s *SugaredLogger) Sync() error {     return s.base.Sync() }

SugaredLogger提供了debug、info、warn、error、panic、dpanic、fatal这几种方法(使用fmt.Sprint的默认格式)，另外还有带f的支持format，带w的方法则支持with键值对

level

zap@v1.16.0/level.go

const (     // DebugLevel logs are typically voluminous, and are usually disabled in     // production.     DebugLevel = zapcore.DebugLevel     // InfoLevel is the default logging priority.     InfoLevel = zapcore.InfoLevel     // WarnLevel logs are more important than Info, but don't need inpidual     // human review.     WarnLevel = zapcore.WarnLevel     // ErrorLevel logs are high-priority. If an application is running smoothly,     // it shouldn't generate any error-level logs.     ErrorLevel = zapcore.ErrorLevel     // DPanicLevel logs are particularly important errors. In development the     // logger panics after writing the message.     DPanicLevel = zapcore.DPanicLevel     // PanicLevel logs a message, then panics.     PanicLevel = zapcore.PanicLevel     // FatalLevel logs a message, then calls os.Exit(1).     FatalLevel = zapcore.FatalLevel )

zap内部的level分为debug、info、warn、error、dpanic、panic、fatal这几种

DPanic

DPanic stands for "panic in development." In development, it logs at PanicLevel; otherwise, it logs at ErrorLevel. DPanic makes it easier to catch errors that are theoretically possible, but shouldn't actually happen, without crashing in production.

DPanic in development

func dpanicInDevelopment() {     logger, _ := zap.NewDevelopment()     defer logger.Sync() // flushes buffer, if any     sugar := logger.Sugar()     sugar.DPanic("test dpanic")     sugar.Info("this will not be logged") }

DPanic在development下的效果跟panic效果类似，最后的info不会被输出

DPanic in production

func dpanicInProduction() {     logger, _ := zap.NewProduction()     defer logger.Sync() // flushes buffer, if any     sugar := logger.Sugar()     sugar.DPanic("test dpanic logged as error in not development mode")     sugar.Info("this will be logged") }

DPanic在非development下则退化为error模式，最后的info照样会输出，这样子在production下比较安全一点。

logger.check

zap@v1.16.0/logger.go

func (log *Logger) check(lvl zapcore.Level, msg string) *zapcore.CheckedEntry {     // check must always be called directly by a method in the Logger interface     // (e.g., Check, Info, Fatal).     const callerSkipOffset = 2      // Check the level first to reduce the cost of disabled log calls.     // Since Panic and higher may exit, we skip the optimization for those levels.     if lvl < zapcore.DPanicLevel && !log.core.Enabled(lvl) {         return nil     }      // Create basic checked entry thru the core; this will be non-nil if the     // log message will actually be written somewhere.     ent := zapcore.Entry{         LoggerName: log.name,         Time:       time.Now(),         Level:      lvl,         Message:    msg,     }     ce := log.core.Check(ent, nil)     willWrite := ce != nil      // Set up any required terminal behavior.     switch ent.Level {     case zapcore.PanicLevel:         ce = ce.Should(ent, zapcore.WriteThenPanic)     case zapcore.FatalLevel:         onFatal := log.onFatal         // Noop is the default value for CheckWriteAction, and it leads to         // continued execution after a Fatal which is unexpected.         if onFatal == zapcore.WriteThenNoop {             onFatal = zapcore.WriteThenFatal         }         ce = ce.Should(ent, onFatal)     case zapcore.DPanicLevel:         if log.development {             ce = ce.Should(ent, zapcore.WriteThenPanic)         }     }      // Only do further annotation if we're going to write this message; checked     // entries that exist only for terminal behavior don't benefit from     // annotation.     if !willWrite {         return ce     }      // Thread the error output through to the CheckedEntry.     ce.ErrorOutput = log.errorOutput     if log.addCaller {         frame, defined := getCallerFrame(log.callerSkip + callerSkipOffset)         if !defined {             fmt.Fprintf(log.errorOutput, "%v Logger.check error: failed to get callern", time.Now().UTC())             log.errorOutput.Sync()         }          ce.Entry.Caller = zapcore.EntryCaller{             Defined:  defined,             PC:       frame.PC,             File:     frame.File,             Line:     frame.Line,             Function: frame.Function,         }     }     if log.addStack.Enabled(ce.Entry.Level) {         ce.Entry.Stack = StackSkip("", log.callerSkip+callerSkipOffset).String     }      return ce }

logger.check方法会判断lvl，如果是zapcore.DPanicLevel，则会进一步判断是否是development模式，如果是会设置ce.Should(ent, zapcore.WriteThenPanic)

小结

• zap内部的level分为debug、info、warn、error、dpanic、panic、fatal这几种
• SugaredLogger提供了debug、info、warn、error、panic、dpanic、fatal这几种方法(使用fmt.Sprint的默认格式)，另外还有带f的支持format，带w的方法则支持with键值对
• DPanic在development下的效果跟panic效果类似，在非development下则退化为error模式