rexCrontab

type Crontab struct {
	*cron.Cron
	TaskPool             map[string]*Task
	Lock                 sync.Mutex
	Register, UnRegister chan *Task
	Close                chan int
	TaskCount            int
}

type Task struct {
	TaskId string // note: 最好用uuid
	Name   string
	Spec   string
	JobId  cron.EntryID
	Job    cron.Job
}