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本文次要钻研一下golang的zap的level

Level

zap@v1.16.0/zapcore/level.go

// A Level is a logging priority. Higher levels are more important.type Level int8const (    // DebugLevel logs are typically voluminous, and are usually disabled in    // production.    DebugLevel Level = iota - 1    // InfoLevel is the default logging priority.    InfoLevel    // WarnLevel logs are more important than Info, but don't need individual    // human review.    WarnLevel    // ErrorLevel logs are high-priority. If an application is running smoothly,    // it shouldn't generate any error-level logs.    ErrorLevel    // DPanicLevel logs are particularly important errors. In development the    // logger panics after writing the message.    DPanicLevel    // PanicLevel logs a message, then panics.    PanicLevel    // FatalLevel logs a message, then calls os.Exit(1).    FatalLevel    _minLevel = DebugLevel    _maxLevel = FatalLevel)func (l Level) String() string {    switch l {    case DebugLevel:        return "debug"    case InfoLevel:        return "info"    case WarnLevel:        return "warn"    case ErrorLevel:        return "error"    case DPanicLevel:        return "dpanic"    case PanicLevel:        return "panic"    case FatalLevel:        return "fatal"    default:        return fmt.Sprintf("Level(%d)", l)    }}
Level为int8类型，其中DebugLevel值最小，FatalLevel值最大

LevelEnabler

zap@v1.16.0/zapcore/level.go

type LevelEnabler interface {    Enabled(Level) bool}func (l Level) Enabled(lvl Level) bool {    return lvl >= l}
LevelEnabler接口定义了Enabled办法，Level的Enabled办法判断lvl是否大于等于l

levelToColor

zap@v1.16.0/zapcore/level_strings.go

import "go.uber.org/zap/internal/color"var (    _levelToColor = map[Level]color.Color{        DebugLevel:  color.Magenta,        InfoLevel:   color.Blue,        WarnLevel:   color.Yellow,        ErrorLevel:  color.Red,        DPanicLevel: color.Red,        PanicLevel:  color.Red,        FatalLevel:  color.Red,    }    _unknownLevelColor = color.Red    _levelToLowercaseColorString = make(map[Level]string, len(_levelToColor))    _levelToCapitalColorString   = make(map[Level]string, len(_levelToColor)))func init() {    for level, color := range _levelToColor {        _levelToLowercaseColorString[level] = color.Add(level.String())        _levelToCapitalColorString[level] = color.Add(level.CapitalString())    }}
level_strings定义了_levelToColor的映射，其中DebugLevel为color.Magenta，InfoLevel为color.Blue，WarnLevel为color.Yellow，其余的为color.Red

levelFilterCore

zap@v1.16.0/zapcore/increase_level.go

type levelFilterCore struct {    core  Core    level LevelEnabler}// NewIncreaseLevelCore creates a core that can be used to increase the level of// an existing Core. It cannot be used to decrease the logging level, as it acts// as a filter before calling the underlying core. If level decreases the log level,// an error is returned.func NewIncreaseLevelCore(core Core, level LevelEnabler) (Core, error) {    for l := _maxLevel; l >= _minLevel; l-- {        if !core.Enabled(l) && level.Enabled(l) {            return nil, fmt.Errorf("invalid increase level, as level %q is allowed by increased level, but not by existing core", l)        }    }    return &levelFilterCore{core, level}, nil}func (c *levelFilterCore) Enabled(lvl Level) bool {    return c.level.Enabled(lvl)}func (c *levelFilterCore) With(fields []Field) Core {    return &levelFilterCore{c.core.With(fields), c.level}}func (c *levelFilterCore) Check(ent Entry, ce *CheckedEntry) *CheckedEntry {    if !c.Enabled(ent.Level) {        return ce    }    return c.core.Check(ent, ce)}func (c *levelFilterCore) Write(ent Entry, fields []Field) error {    return c.core.Write(ent, fields)}func (c *levelFilterCore) Sync() error {    return c.core.Sync()}
levelFilterCore定义了Core、LevelEnabler属性；其Check办法首先通过c.Enabled(ent.Level)判断entry的level是否大于等于core的level，如果满足条件才执行c.core.Check(ent, ce)，否则间接返回

IncreaseLevel

zap@v1.16.0/options.go

func IncreaseLevel(lvl zapcore.LevelEnabler) Option {    return optionFunc(func(log *Logger) {        core, err := zapcore.NewIncreaseLevelCore(log.core, lvl)        if err != nil {            fmt.Fprintf(log.errorOutput, "failed to IncreaseLevel: %v\n", err)        } else {            log.core = core        }    })}
IncreaseLevel会通过zapcore.NewIncreaseLevelCore创立一个新的core，它包装了原来的core，并设置了zapcore.LevelEnabler

实例

func levelDemo() {    logger, err := zap.NewDevelopment()    defer logger.Sync()    if err != nil {        panic(err)    }    infoLog := logger.WithOptions(zap.IncreaseLevel(zapcore.InfoLevel))    logger.Debug("this is debug log")    infoLog.Debug("this will be dropped")}

输入

2020-12-21T22:44:12.385+0800    DEBUG   zap/zap_demo.go:29      this is debug log

小结

Level为int8类型，其中DebugLevel值最小，FatalLevel值最大；LevelEnabler接口定义了Enabled办法，Level的Enabled办法判断lvl是否大于等于l；levelFilterCore定义了Core、LevelEnabler属性；其Check办法首先通过c.Enabled(ent.Level)判断entry的level是否大于等于core的level，如果满足条件才执行c.core.Check(ent, ce)，否则间接返回。

doc

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