Golang Connection.GetW方法代碼示例

// wait waits for an individual service state to reach its desired state
func wait(shutdown <-chan interface{}, conn client.Connection, serviceID, stateID string, dstate service.DesiredState) error {
	for {
		var node ServiceStateNode
		event, err := conn.GetW(servicepath(serviceID, stateID), &node)
		if err == client.ErrNoNode {
			// if the node no longer exists, then there is nothing to watch, so we are done
			return nil
		} else if err != nil {
			glog.Errorf("Got an error while looking for %s (%s): %s", stateID, serviceID, err)
			return err
		}

		switch dstate {
		case service.SVCStop:
			// pass through, because the node needs to be deleted to be considered Stopped
		case service.SVCRun, service.SVCRestart:
			if node.IsRunning() {
				// instance reached the desired state
				return nil
			}
		case service.SVCPause:
			if node.IsPaused() {
				// instance reached the desired state
				return nil
			}
		}

		// wait for something to change on the node or shutdown
		select {
		case <-event:
		case <-shutdown:
			return zzk.ErrShutdown
		}
	}
}

func (r *registryType) watchItem(conn client.Connection, path string, nodeType client.Node, cancel <-chan bool, processNode func(conn client.Connection,
	node client.Node), errorHandler WatchError) error {
	exists, err := zzk.PathExists(conn, path)
	if err != nil {
		return err
	}
	if !exists {
		return client.ErrNoNode
	}
	for {
		event, err := conn.GetW(path, nodeType)
		if err != nil {
			glog.Errorf("Could not watch %s: %s", path, err)
			defer errorHandler(path, err)
			return err
		}
		processNode(conn, nodeType)
		//This blocks until a change happens under the key
		select {
		case ev := <-event:
			glog.V(2).Infof("watch event %+v at path: %s", ev, path)
		case <-cancel:
			return nil
		}

	}
	return nil
}

func MonitorResourcePool(shutdown <-chan interface{}, conn client.Connection, poolID string) <-chan *pool.ResourcePool {
	monitor := make(chan *pool.ResourcePool)
	go func() {
		defer close(monitor)
		if err := zzk.Ready(shutdown, conn, poolpath(poolID)); err != nil {
			glog.V(2).Infof("Could not watch pool %s: %s", poolID, err)
			return
		}
		for {
			var node PoolNode
			event, err := conn.GetW(poolpath(poolID), &node)
			if err != nil {
				glog.V(2).Infof("Could not get pool %s: %s", poolID, err)
				return
			}

			select {
			case monitor <- node.ResourcePool:
			case <-shutdown:
				return
			}

			select {
			case <-event:
			case <-shutdown:
				return
			}
		}
	}()
	return monitor
}