Golang Interface.Stop方法代码示例

// Until reads items from the watch until each provided condition succeeds, and then returns the last watch
// encountered. The first condition that returns an error terminates the watch (and the event is also returned).
// If no event has been received, the returned event will be nil.
// TODO: move to pkg/watch upstream
func Until(timeout time.Duration, watcher watch.Interface, conditions ...WatchConditionFunc) (*watch.Event, error) {
	ch := watcher.ResultChan()
	defer watcher.Stop()
	var after <-chan time.Time
	if timeout > 0 {
		after = time.After(timeout)
	} else {
		ch := make(chan time.Time)
		close(ch)
		after = ch
	}
	var lastEvent *watch.Event
	for _, condition := range conditions {
		for {
			select {
			case event, ok := <-ch:
				if !ok {
					return lastEvent, wait.ErrWaitTimeout
				}
				lastEvent = &event
				// TODO: check for watch expired error and retry watch from latest point?
				done, err := condition(event)
				if err != nil {
					return lastEvent, err
				}
				if done {
					return lastEvent, nil
				}
			case <-after:
				return lastEvent, wait.ErrWaitTimeout
			}
		}
	}
	return lastEvent, wait.ErrWaitTimeout
}

// watchHandler watches w and keeps *resourceVersion up to date.
func (r *Reflector) watchHandler(w watch.Interface, resourceVersion *string, resyncCh <-chan time.Time, stopCh <-chan struct{}) error {
	start := time.Now()
	eventCount := 0

	// Stopping the watcher should be idempotent and if we return from this function there's no way
	// we're coming back in with the same watch interface.
	defer w.Stop()

loop:
	for {
		select {
		case <-stopCh:
			return errorStopRequested
		case <-resyncCh:
			return errorResyncRequested
		case event, ok := <-w.ResultChan():
			if !ok {
				break loop
			}
			if event.Type == watch.Error {
				return apierrs.FromObject(event.Object)
			}
			if e, a := r.expectedType, reflect.TypeOf(event.Object); e != nil && e != a {
				utilruntime.HandleError(fmt.Errorf("%s: expected type %v, but watch event object had type %v", r.name, e, a))
				continue
			}
			meta, err := meta.Accessor(event.Object)
			if err != nil {
				utilruntime.HandleError(fmt.Errorf("%s: unable to understand watch event %#v", r.name, event))
				continue
			}
			newResourceVersion := meta.GetResourceVersion()
			switch event.Type {
			case watch.Added:
				r.store.Add(event.Object)
			case watch.Modified:
				r.store.Update(event.Object)
			case watch.Deleted:
				// TODO: Will any consumers need access to the "last known
				// state", which is passed in event.Object? If so, may need
				// to change this.
				r.store.Delete(event.Object)
			default:
				utilruntime.HandleError(fmt.Errorf("%s: unable to understand watch event %#v", r.name, event))
			}
			*resourceVersion = newResourceVersion
			r.setLastSyncResourceVersion(newResourceVersion)
			eventCount++
		}
	}

	watchDuration := time.Now().Sub(start)
	if watchDuration < 1*time.Second && eventCount == 0 {
		glog.V(4).Infof("%s: Unexpected watch close - watch lasted less than a second and no items received", r.name)
		return errors.New("very short watch")
	}
	glog.V(4).Infof("%s: Watch close - %v total %v items received", r.name, r.expectedType, eventCount)
	return nil
}

// WatchLoop loops, passing events in w to fn.
// If user sends interrupt signal, shut down cleanly. Otherwise, never return.
func WatchLoop(w watch.Interface, fn func(watch.Event) error) {
	signals := make(chan os.Signal, 1)
	signal.Notify(signals, os.Interrupt)
	defer signal.Stop(signals)
	for {
		select {
		case event, ok := <-w.ResultChan():
			if !ok {
				return
			}
			if err := fn(event); err != nil {
				w.Stop()
			}
		case <-signals:
			w.Stop()
		}
	}
}

func watcher(ctx context.Context) {
	debugf("starting watcher\n")

	var closed = watch.Event{}
	var w watch.Interface
	var wchan = make(chan watch.Interface)
	defer close(wchan)

	for {

		go acquireWatch(ctx, wchan)

		select {
		case w = <-wchan:
			debugf("watch acquired\n")
		case <-ctx.Done():
			debugf("watcher cancelled\n")
			return
		}

	loop:
		for {
			select {
			case e := <-w.ResultChan():
				if e == closed {
					debugf("watcher closed channel with event: %+v\n", e)
					break loop
				}
				handleWatchEvent(e)
			case <-ctx.Done():
				w.Stop()
				debugf("watcher cancelled\n")
				return
			}
		}
	}
}

// watchRollbackEvent watches for rollback events and returns rollback result
func watchRollbackEvent(w watch.Interface) string {
	signals := make(chan os.Signal, 1)
	signal.Notify(signals, os.Interrupt, os.Kill, syscall.SIGTERM)
	for {
		select {
		case event, ok := <-w.ResultChan():
			if !ok {
				return ""
			}
			obj, ok := event.Object.(*api.Event)
			if !ok {
				w.Stop()
				return ""
			}
			isRollback, result := isRollbackEvent(obj)
			if isRollback {
				w.Stop()
				return result
			}
		case <-signals:
			w.Stop()
		}
	}
}