etcd-io__etcd/store/watcher.go

package store

type watcher struct {
	eventChan  chan *Event
	recursive  bool
	sinceIndex uint64
}

// notify function notifies the watcher. If the watcher interests in the given path,
// the function will return true.
func (w *watcher) notify(e *Event, originalPath bool, deleted bool) bool {
	// watcher is interested the path in three cases and under one condition
	// the condition is that the event happens after the watcher's sinceIndex

	// 1. the path at which the event happens is the path the watcher is watching at.
	// For example if the watcher is watching at "/foo" and the event happens at "/foo",
	// the watcher must be interested in that event.

	// 2. the watcher is a recursive watcher, it interests in the event happens after
	// its watching path. For example if watcher A watches at "/foo" and it is a recursive
	// one, it will interest in the event happens at "/foo/bar".

	// 3. when we delete a directory, we need to force notify all the watchers who watches
	// at the file we need to delete.
	// For example a watcher is watching at "/foo/bar". And we deletes "/foo". The watcher
	// should get notified even if "/foo" is not the path it is watching.

	if (w.recursive || originalPath || deleted) && e.Index >= w.sinceIndex {
		w.eventChan <- e
		return true
	}
	return false
}