func (d *delayQueue) Closed() <-chan struct{} {
	done := make(chan struct{})
	go func() {
		for _, ch := range d.workerStopped {
			<-ch
		}
		close(done)
	}()
	return done
}

func (d *delayQueue) Run(stop <-chan struct{}) {
	for i := 0; i < d.workers; i++ {
		d.workerStopped = append(d.workerStopped, d.work(stop))
	}

	push := func(t *delayTask) bool {
		select {
		case d.execute <- t: