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本文主要研究一下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 int8
const (
// 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方法，Level的Enabled方法判断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方法首先通过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)，否则直接返回
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创建一个新的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")
}
输出
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方法，Level的Enabled方法判断lvl是否大于等于l；levelFilterCore定义了Core、LevelEnabler属性；其Check方法首先通过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)，否则直接返回。
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