code: func (f *FileLogger) initLoggerByDaily() {
  
  	t, _ := time.Parse(DATEFORMAT, time.Now().Format(DATEFORMAT))
  
  	f.date = &t
  	f.mu.Lock()
  	defer f.mu.Unlock()
  
  	logFile := joinFilePath(f.fileDir, f.fileName)
  	if !f.isMustSplit() {
  		if !isExist(f.fileDir) {
  			os.Mkdir(f.fileDir, 0755)
  		}
  		f.logFile, _ = os.OpenFile(logFile, os.O_RDWR|os.O_APPEND|os.O_CREATE, 0666)
  		f.lg = log.New(f.logFile, f.prefix, log.LstdFlags|log.Lmicroseconds)
  	} else {
  		f.split()
  	}
  
  	go f.logWriter()
  	go f.fileMonitor()
  }
docs: // init fileLogger split by daily