Golang Connection.NewLeader方法代碼示例

func (s *Server) Run(shutdown <-chan interface{}, conn client.Connection) error {
	node := &Node{
		Host:       *s.host,
		ExportPath: fmt.Sprintf("%s:%s", s.host.IPAddr, s.driver.ExportPath()),
		ExportTime: strconv.FormatInt(time.Now().UnixNano(), 16),
	}

	// Create the storage leader and client nodes
	if exists, _ := conn.Exists("/storage/leader"); !exists {
		conn.CreateDir("/storage/leader")
	}

	storageClientsPath := "/storage/clients"

	if exists, _ := conn.Exists(storageClientsPath); !exists {
		conn.CreateDir(storageClientsPath)
	}

	leader := conn.NewLeader("/storage/leader", node)
	leaderW, err := leader.TakeLead()
	if err != zookeeper.ErrDeadlock && err != nil {
		glog.Errorf("Could not take storage lead: %s", err)
		return err
	}

	// monitor dfs; log warnings each cycle; restart dfs if needed
	go s.monitor.MonitorDFSVolume(path.Join("/exports", s.driver.ExportPath()), s.host.IPAddr, node.ExportTime, shutdown, s.monitor.DFSVolumeMonitorPollUpdateFunc)

	// loop until shutdown event
	defer leader.ReleaseLead()

	for {
		clients, clientW, err := conn.ChildrenW(storageClientsPath)
		if err != nil {
			glog.Errorf("Could not set up watch for storage clients: %s", err)
			return err
		}

		s.monitor.SetMonitorStorageClients(conn, storageClientsPath)
		s.driver.SetClients(clients...)
		if err := s.driver.Sync(); err != nil {
			glog.Errorf("Error syncing driver: %s", err)
			return err
		}

		select {
		case e := <-clientW:
			glog.Info("storage.server: receieved event: %s", e)
		case <-leaderW:
			err := fmt.Errorf("storage.server: lost lead")
			return err
		case <-shutdown:
			return nil
		}
	}
}

func MonitorRealm(shutdown <-chan interface{}, conn client.Connection, path string) <-chan string {
	realmC := make(chan string)

	go func() {
		defer close(realmC)
		var realm string
		leader := conn.NewLeader(path, &HostLeader{})
		for {
			// monitor path for changes
			_, event, err := conn.ChildrenW(path)
			if err != nil {
				return
			}

			// Get the current leader and check for changes in its realm
			var hl HostLeader
			if err := leader.Current(&hl); err == zookeeper.ErrNoLeaderFound {
				// pass
			} else if err != nil {
				return
			} else if hl.Realm != realm {
				realm = hl.Realm
				select {
				case realmC <- realm:
				case <-shutdown:
					return
				}
			}

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

// NewHostLeader initializes a new host leader
func NewHostLeader(conn client.Connection, hostID, realm, path string) client.Leader {
	return conn.NewLeader(path, &HostLeader{HostID: hostID, Realm: realm})
}