logrus
实现多个实例
func New() *Logger {
return &Logger{
Out: os.Stderr,
Formatter: new(TextFormatter),
Hooks: make(LevelHooks),
Level: InfoLevel,
ExitFunc: os.Exit,
ReportCaller: false,
}
}
默认实例
var (
// std is the name of the standard logger in stdlib `log`
std = New()
)
Pool 使用
// Reusable empty entry
entryPool sync.Pool
func (logger *Logger) newEntry() *Entry {
entry, ok := logger.entryPool.Get().(*Entry)
if ok {
return entry
}
return NewEntry(logger)
}
func (logger *Logger) releaseEntry(entry *Entry) {
entry.Data = map[string]interface{}{}
logger.entryPool.Put(entry)
}
核心代码
entry log
// This function is not declared with a pointer value because otherwise
// race conditions will occur when using multiple goroutines
func (entry Entry) log(level Level, msg string) {
var buffer *bytes.Buffer
// Default to now, but allow users to override if they want.
//
// We don't have to worry about polluting future calls to Entry#log()
// with this assignment because this function is declared with a
// non-pointer receiver.
if entry.Time.IsZero() {
entry.Time = time.Now()
}
entry.Level = level
entry.Message = msg
entry.Logger.mu.Lock()
if entry.Logger.ReportCaller {
entry.Caller = getCaller()
}
entry.Logger.mu.Unlock()
entry.fireHooks()
buffer = getBuffer()
defer func() {
entry.Buffer = nil
putBuffer(buffer)
}()
buffer.Reset()
entry.Buffer = buffer
entry.write()
entry.Buffer = nil
// To avoid Entry#log() returning a value that only would make sense for
// panic() to use in Entry#Panic(), we avoid the allocation by checking
// directly here.
if level <= PanicLevel {
panic(&entry)
}
}
扩展实现
统一接口,面向接口开发
type Hook interface {
Levels() []Level
Fire(*Entry) error
}
type Formatter interface {
Format(*Entry) ([]byte, error)
}
func (entry *Entry) fireHooks() {
entry.Logger.mu.Lock()
defer entry.Logger.mu.Unlock()
err := entry.Logger.Hooks.Fire(entry.Level, entry)
if err != nil {
fmt.Fprintf(os.Stderr, "Failed to fire hook: %v
", err)
}
}
func (entry *Entry) write() {
entry.Logger.mu.Lock()
defer entry.Logger.mu.Unlock()
serialized, err := entry.Logger.Formatter.Format(entry)
if err != nil {
fmt.Fprintf(os.Stderr, "Failed to obtain reader, %v
", err)
return
}
if _, err = entry.Logger.Out.Write(serialized); err != nil {
fmt.Fprintf(os.Stderr, "Failed to write to log, %v
", err)
}
}