java – 如何有效地使用LeaderElection配方使用Zookeeper的策展

我正在使用Apache Curator图书馆在Zookeeper上进行领导选举.我的应用程序代码部署在各种机器中,我需要从一台机器执行我的代码,这就是为什么我在zookeeper上进行领导选举,以便我可以检查我是否是领导者,然后执行此代码.

以下是我的LeaderElectionExecutor类,它确保每个应用程序都有一个策展人实例

public class LeaderElectionExecutor {

    private ZookeeperClient zookClient;

    private static final String LEADER_NODE = "/testleader";

    private static class Holder {
        static final LeaderElectionExecutor INSTANCE = new LeaderElectionExecutor();
    }

    public static LeaderElectionExecutor getInstance() {
        return Holder.INSTANCE;
    }

    private LeaderElectionExecutor() {
        try {
            String hostname = Utils.getHostName();

            String nodes = "host1:2181,host2:2181;

            zookClient = new ZookeeperClient(nodes,LEADER_NODE,hostname);
            zookClient.start();

            // added sleep specifically for the leader to get selected
            // since I cannot call isLeader method immediately after starting the latch
            TimeUnit.MINUTES.sleep(1);
        } catch (Exception ex) {
            // logging error
            System.exit(1);
        }
    }

    public ZookeeperClient getZookClient() {
        return zookClient;
    }
}

以下是我的ZookeeperClient代码 –

// can this class be improved in any ways?
public class ZookeeperClient {

    private CuratorFramework client;
    private String latchPath;
    private String id;
    private LeaderLatch leaderLatch;

    public ZookeeperClient(String connString,String latchPath,String id) {
        client = CuratorFrameworkFactory.newClient(connString,new ExponentialBackoffRetry(1000,Integer.MAX_VALUE));
        this.id = id;
        this.latchPath = latchPath;
    }

    public void start() throws Exception {
        client.start();
        leaderLatch = new LeaderLatch(client,latchPath,id);
        leaderLatch.start();
    }

    public boolean isLeader() {
        return leaderLatch.hasLeadership();
    }

    public Participant currentLeader() throws Exception {
        return leaderLatch.getLeader();
    }

    public void close() throws IOException {
        leaderLatch.close();
        client.close();
    }

    public CuratorFramework getClient() {
        return client;
    }

    public String getLatchPath() {
        return latchPath;
    }

    public String getId() {
        return id;
    }

    public LeaderLatch getLeaderLatch() {
        return leaderLatch;
    }
}

现在在我的应用程序中,我正在使用这样的代码 –

public void method01() {
    ZookeeperClient zookClient = LeaderElectionExecutor.getInstance().getZookClient();
    if (zookClient.isLeader()) {
        // do something
    }
}

public void method02() {
    ZookeeperClient zookClient = LeaderElectionExecutor.getInstance().getZookClient();
    if (zookClient.isLeader()) {
        // do something
    }
}

问题陈述：-

在策展人库中 – 调用isLeader()在启动锁定后立即不起作用.领导选择需要时间.而且由于这个原因,我已经在我的LeaderElectionExecutor代码中添加了1分钟的睡眠,但是我觉得这不是正确的方法.

有没有更好的办法呢？记住这一点,我需要一种方法来检查我是否是领导者,然后执行这段代码.我不能在一个方法中做所有事情,所以我需要调用来自不同类和方法的isLeader方法来检查我是否是领导者,然后执行这段代码.

我正在使用Zookeeper 3.4.5和Curator 1.7.1版本.

@Component
public class LeadershipWatcher implements Runnable {
  private final LeaderLatch leaderLatch;
  private final Collection<LeadershipObserver> leadershipObservers;

  /* constructor with @Inject */

  @Override
  public void run() {
    try {
      leaderLatch.await();

      for (LeadershipObserver observer : leadershipObservers) {
        observer.granted();
      }
    } catch (InterruptedException e) {
      for (LeadershipObserver observer : leadershipObservers) {
        observer.interrupted();
      }
    }
  }
}