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sleeper_task.go
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sleeper_task.go
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package services
// SleeperTask represents a task that waits in the background to process some work.
type SleeperTask interface {
Stop() error
WakeUp()
}
// Worker is a simple interface that represents some work to do repeatedly
type Worker interface {
Work()
}
type sleeperTask struct {
worker Worker
chQueue chan struct{}
chQueueDone chan struct{}
}
// NewSleeperTask takes a worker and returns a SleeperTask.
//
// SleeperTask is guaranteed to call Work on the worker at least once for every
// WakeUp call.
// If the Worker is busy when WakeUp is called, the Worker will be called again
// immediately after it is finished. For this reason you should take care to
// make sure that Worker is idempotent.
// WakeUp does not block.
//
func NewSleeperTask(worker Worker) SleeperTask {
s := &sleeperTask{
worker: worker,
chQueue: make(chan struct{}, 1),
chQueueDone: make(chan struct{}),
}
go s.workerLoop()
return s
}
// Stop stops the SleeperTask. It never returns an error. Its error return
// exists so as to satisfy other interfaces.
func (s *sleeperTask) Stop() error {
close(s.chQueue)
<-s.chQueueDone
return nil
}
// WakeUp wakes up the sleeper task, asking it to execute its Worker.
func (s *sleeperTask) WakeUp() {
select {
case s.chQueue <- struct{}{}:
default:
}
}
func (s *sleeperTask) workerLoop() {
defer close(s.chQueueDone)
for range s.chQueue {
s.worker.Work()
}
if len(s.chQueue) > 0 {
s.worker.Work()
}
}