聊聊golang的zap的NewTee

序

本文主要研究一下golang的zap的NewTee

NewTee

zap@v1.16.0/zapcore/tee.go

type multiCore []Core

func NewTee(cores ...Core) Core {
	switch len(cores) {
	case 0:
		return NewNopCore()
	case 1:
		return cores[0]
	default:
		return multiCore(cores)
	}
}

NewTee方法根据cores个数来返回不同的Core，若len(cores)为0，返回NewNopCore，若为1则返回cores[0]，默认返回[]Core

multiCore

zap@v1.16.0/zapcore/tee.go

func (mc multiCore) With(fields []Field) Core {
	clone := make(multiCore, len(mc))
	for i := range mc {
		clone[i] = mc[i].With(fields)
	}
	return clone
}

func (mc multiCore) Enabled(lvl Level) bool {
	for i := range mc {
		if mc[i].Enabled(lvl) {
			return true
		}
	}
	return false
}

func (mc multiCore) Check(ent Entry, ce *CheckedEntry) *CheckedEntry {
	for i := range mc {
		ce = mc[i].Check(ent, ce)
	}
	return ce
}

func (mc multiCore) Write(ent Entry, fields []Field) error {
	var err error
	for i := range mc {
		err = multierr.Append(err, mc[i].Write(ent, fields))
	}
	return err
}

func (mc multiCore) Sync() error {
	var err error
	for i := range mc {
		err = multierr.Append(err, mc[i].Sync())
	}
	return err
}

multiCore提供了With、Enabled、Check、Write、Sync方法，它们都是遍历multiCore执行对应的操作

实例

func teeDemo() {
	buf := &bytes.Buffer{}
	teeCore := zapcore.NewTee(
		zapcore.NewCore(zapcore.NewJSONEncoder(zap.NewProductionEncoderConfig()), zapcore.AddSync(buf), zap.InfoLevel),
		zapcore.NewCore(zapcore.NewConsoleEncoder(zap.NewDevelopmentEncoderConfig()), zapcore.Lock(os.Stdout), zap.InfoLevel),
	)
	logger := zap.New(teeCore)
	logger.Info("hello")
	fmt.Print(buf)
}

这里zapcore.NewTee将json及console两个core衔接在一起，创建logger，之后logger会往两个core写入数据

输出

2020-12-12T22:29:47.328+0800	INFO	hello
{"level":"info","ts":1607783387.3285708,"msg":"hello"}

小结

zapcore.NewTee方法可以把多个core衔接在一起，对应logger的操作会同时操作这些core。

doc

• zap