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本文主要研究一下golang的zap的NewExample
NewExample
zap@v1.16.0/logger.go
func NewExample(options ...Option) *Logger {
encoderCfg := zapcore.EncoderConfig{
MessageKey: "msg",
LevelKey: "level",
NameKey: "logger",
EncodeLevel: zapcore.LowercaseLevelEncoder,
EncodeTime: zapcore.ISO8601TimeEncoder,
EncodeDuration: zapcore.StringDurationEncoder,
}
core := zapcore.NewCore(zapcore.NewJSONEncoder(encoderCfg), os.Stdout, DebugLevel)
return New(core).WithOptions(options...)
}
NewExample使用通过core来创建Logger,其中core使用的Encoder为JSONEncoder,WriteSyncer使用的是os.Stdout,LevelEnabler使用的是DebugLevel;使用的JSONEncoder的zapcore.EncoderConfig其EncodeLevel为zapcore.LowercaseLevelEncoder,其TimeEncoder为zapcore.ISO8601TimeEncoder,,其DurationEncoder为zapcore.StringDurationEncoder
encoder
zap@v1.16.0/zapcore/encoder.go
func LowercaseLevelEncoder(l Level, enc PrimitiveArrayEncoder) {
enc.AppendString(l.String())
}
func ISO8601TimeEncoder(t time.Time, enc PrimitiveArrayEncoder) {
encodeTimeLayout(t, "2006-01-02T15:04:05.000Z0700", enc)
}
func StringDurationEncoder(d time.Duration, enc PrimitiveArrayEncoder) {
enc.AppendString(d.String())
}
LowercaseLevelEncoder使用小写打印log level;ISO8601TimeEncoder使用
2006-01-02T15:04:05.000Z0700
格式打印时间;StringDurationEncoder使用Duration内置的String()打印time.Duration
NewJSONEncoder
zap@v1.16.0/zapcore/json_encoder.go
func NewJSONEncoder(cfg EncoderConfig) Encoder {
return newJSONEncoder(cfg, false)
}
func newJSONEncoder(cfg EncoderConfig, spaced bool) *jsonEncoder {
return &jsonEncoder{
EncoderConfig: &cfg,
buf: bufferpool.Get(),
spaced: spaced,
}
}
func (enc *jsonEncoder) EncodeEntry(ent Entry, fields []Field) (*buffer.Buffer, error) {
final := enc.clone()
final.buf.AppendByte('{')
if final.LevelKey != "" {
final.addKey(final.LevelKey)
cur := final.buf.Len()
final.EncodeLevel(ent.Level, final)
if cur == final.buf.Len() {
// User-supplied EncodeLevel was a no-op. Fall back to strings to keep
// output JSON valid.
final.AppendString(ent.Level.String())
}
}
if final.TimeKey != "" {
final.AddTime(final.TimeKey, ent.Time)
}
if ent.LoggerName != "" && final.NameKey != "" {
final.addKey(final.NameKey)
cur := final.buf.Len()
nameEncoder := final.EncodeName
// if no name encoder provided, fall back to FullNameEncoder for backwards
// compatibility
if nameEncoder == nil {
nameEncoder = FullNameEncoder
}
nameEncoder(ent.LoggerName, final)
if cur == final.buf.Len() {
// User-supplied EncodeName was a no-op. Fall back to strings to
// keep output JSON valid.
final.AppendString(ent.LoggerName)
}
}
if ent.Caller.Defined {
if final.CallerKey != "" {
final.addKey(final.CallerKey)
cur := final.buf.Len()
final.EncodeCaller(ent.Caller, final)
if cur == final.buf.Len() {
// User-supplied EncodeCaller was a no-op. Fall back to strings to
// keep output JSON valid.
final.AppendString(ent.Caller.String())
}
}
if final.FunctionKey != "" {
final.addKey(final.FunctionKey)
final.AppendString(ent.Caller.Function)
}
}
if final.MessageKey != "" {
final.addKey(enc.MessageKey)
final.AppendString(ent.Message)
}
if enc.buf.Len() > 0 {
final.addElementSeparator()
final.buf.Write(enc.buf.Bytes())
}
addFields(final, fields)
final.closeOpenNamespaces()
if ent.Stack != "" && final.StacktraceKey != "" {
final.AddString(final.StacktraceKey, ent.Stack)
}
final.buf.AppendByte('}')
if final.LineEnding != "" {
final.buf.AppendString(final.LineEnding)
} else {
final.buf.AppendString(DefaultLineEnding)
}
ret := final.buf
putJSONEncoder(final)
return ret, nil
}
NewJSONEncoder创建的是jsonEncoder;其EncodeEntry方法一次打印LevelKey、TimeKey、LoggerName、Caller,最后才是业务的message本身,然后结束json打印,对于有stacktrace还会以非json的形式(普通堆栈形式)打印stacktrace
实例
func exampleDemo() {
logger := zap.NewExample()
defer logger.Sync() // flushes buffer, if any
sugar := logger.Sugar()
sugar.Info("this will be logged")
sugar.Info("time=", time.Now())
sugar.Panic("test panic")
}
输出
{"level":"info","msg":"this will be logged"}
{"level":"info","msg":"time=2020-12-07 23:14:48.50402 +0800 CST m=+0.000602110"}
{"level":"panic","msg":"test panic"}
panic: test panic
goroutine 1 [running]:
go.uber.org/zap/zapcore.(*CheckedEntry).Write(0xc0001680c0, 0x0, 0x0, 0x0)
/go/pkg/mod/go.uber.org/zap@v1.16.0/zapcore/entry.go:234 +0x585
go.uber.org/zap.(*SugaredLogger).log(0xc000179e98, 0xc000054e04, 0x0, 0x0, 0xc000179ea0, 0x1, 0x1, 0x0, 0x0, 0x0)
/go/pkg/mod/go.uber.org/zap@v1.16.0/sugar.go:234 +0xf6
go.uber.org/zap.(*SugaredLogger).Panic(...)
/go/pkg/mod/go.uber.org/zap@v1.16.0/sugar.go:123
main.exampleDemo()
/zap_demo.go:19 +0x277
main.main()
/zap_demo.go:10 +0x25
exit status 2
小结
NewExample使用通过core来创建Logger,其中core使用的Encoder为JSONEncoder,WriteSyncer使用的是os.Stdout,LevelEnabler使用的是DebugLevel;NewJSONEncoder创建的是jsonEncoder;其EncodeEntry方法一次打印LevelKey、TimeKey、LoggerName、Caller,最后才是业务的message本身,然后结束json打印,对于有stacktrace还会以非json的形式(普通堆栈形式)打印stacktrace
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