How to use

newChildWatcher

method

in

me.hao0.antares.common.zk.ZkClient

/**
 * new a watcher of path child
 * @param path the parent path
 * @param listener a listener
 * NOTE:
 *   Only watch first level children, not recursive
 */
public ChildWatcher newChildWatcher(String path, ChildListener listener) {
  return newChildWatcher(path, listener, Boolean.TRUE);
}

private void listenOnServerChanged() {
  zk.newChildWatcher(ZkPaths.SERVERS, new ChildListener() {
    @Override
    protected void onAdd(String path, byte[] data) {
      String server = ZkPaths.lastNode(path);
      client.addHttpServer(server);
      log.info("The server({}) joined.", server);
    }
    @Override
    protected void onDelete(String path) {
      String server = ZkPaths.lastNode(path);
      client.removeHttpServer(server);
      log.info("The server({}) left.", server);
    }
  });
}

@Override
public void doStart(){
  // watching the alive servers
  watcher = zk.client().newChildWatcher(ZkPaths.SERVERS, new ChildListener() {
    @Override
    protected void onAdd(String path, byte[] data) {
      String server = ZkPaths.lastNode(path);
      if (!alives.contains(server)){
        alives.add(server);
        notifyListeners(server, true);
        Logs.info("The server ({}) is joined.", server);
      }
    }
    @Override
    protected void onDelete(String path) {
      String server = ZkPaths.lastNode(path);
      if(alives.remove(server)){
        notifyListeners(server, false);
        Logs.warn("The server ({}) is left.", server);
      }
    }
  });
}

@Override
public void doStart() {
  // listen app's clients change
  watcher = zk.client().newChildWatcher(ZkPaths.pathOfAppClients(appName), new ChildListener() {
    @Override
    protected void onAdd(String path, byte[] data) {
      // not started, or has shutdown
      // prevent multiple redundant notifies before started
      if (!started || shutdowned) {
        return;
      }
      String client = ZkPaths.lastNode(path);
      if (alives.contains(client)){
        return;
      }
      alives.add(client);
      onClientChanged(appName, client, true);
      Logs.info("The app({})'s client({}) joined.", appName, client);
    }
    @Override
    protected void onDelete(String path) {
      String client = ZkPaths.lastNode(path);
      alives.remove(client);
      onClientChanged(appName, client, false);
      Logs.info("The app({})'s client({}) left.", appName, client);
    }
  });
}

@Override
public void doStart() {
  String appName = client.getAppName();
  String jobClass = getJobClass();
  String jobInstancesNodePath = ZkPaths.pathOfJobInstances(appName, jobClass);
  this.watcher = client.getZk().newChildWatcher(jobInstancesNodePath, new ChildListener() {
    @Override
    protected void onAdd(String path, byte[] data) {
      // fired a new job instance
      String instanceId = ZkPaths.lastNode(path);
      if (Strings.isNullOrEmpty(instanceId)) return;
      // execute the job
      client.getJobExecutor().execute(Long.valueOf(instanceId), ZkJob.this);
    }
  });
}