Examples with Watcher org.apache.zookeeper.Watcher used on opensource projects

Example 26 with Watcher

use of org.apache.zookeeper.Watcher in project commons by twitter.

the class SingletonServiceTest method testNonLeaderDisconnect.

@Test
public void testNonLeaderDisconnect() throws Exception {
    CountDownLatch elected = new CountDownLatch(1);
    listener.onLeading(EasyMock.<LeaderControl>anyObject());
    expectLastCall().andAnswer(countDownAnswer(elected));
    listener.onDefeated(null);
    expectLastCall().anyTimes();
    control.replay();
    ZooKeeperClient zkClient = createZkClient();
    String path = "/fake/path";
    // Create a fake leading candidate node to ensure that the leader in this test is never
    // elected.
    ZooKeeperUtils.ensurePath(zkClient, ZooKeeperUtils.OPEN_ACL_UNSAFE, path);
    String leaderNode = zkClient.get().create(path + "/" + SingletonService.LEADER_ELECT_NODE_PREFIX, "fake_leader".getBytes(), ZooKeeperUtils.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT_SEQUENTIAL);
    serverSet = new ServerSetImpl(zkClient, path);
    candidate = SingletonService.createSingletonCandidate(zkClient, path, ZooKeeperUtils.OPEN_ACL_UNSAFE);
    DefeatOnDisconnectLeader leader = new DefeatOnDisconnectLeader(zkClient, listener);
    service = new SingletonService(serverSet, candidate);
    service.lead(InetSocketAddress.createUnresolved("foo", PORT_A), ImmutableMap.of("http-admin", InetSocketAddress.createUnresolved("foo", PORT_B)), leader);
    final CountDownLatch disconnected = new CountDownLatch(1);
    zkClient.register(new Watcher() {

        @Override
        public void process(WatchedEvent event) {
            if ((event.getType() == EventType.None) && (event.getState() == KeeperState.Disconnected)) {
                disconnected.countDown();
            }
        }
    });
    shutdownNetwork();
    disconnected.await();
    restartNetwork();
    zkClient.get().delete(leaderNode, ZooKeeperUtils.ANY_VERSION);
    // Upon deletion of the fake leader node, the candidate should become leader.
    elected.await();
}

Example 27 with Watcher

use of org.apache.zookeeper.Watcher in project pulsar by yahoo.

the class LeaderElectionService method elect.

/**
     * We try to get the data in the ELECTION_ROOT node. If the node is present (i.e. leader is present), we store it in
     * the currentLeader and keep a watch on the election node. If we lose the leader, then watch gets triggered and we
     * do the election again. If the node does not exist while getting the data, we get NoNodeException. This means,
     * there is no leader and we create the node at ELECTION_ROOT and write the leader broker's service URL in the node.
     * Once the leader is known, we call the listener method so that leader can take further actions.
     */
private void elect() {
    try {
        byte[] data = zkClient.getData(ELECTION_ROOT, new Watcher() {

            @Override
            public void process(WatchedEvent event) {
                log.warn("Type of the event is [{}] and path is [{}]", event.getType(), event.getPath());
                switch(event.getType()) {
                    case NodeDeleted:
                        log.warn("Election node {} is deleted, attempting re-election...", event.getPath());
                        if (event.getPath().equals(ELECTION_ROOT)) {
                            log.info("This should call elect again...");
                            executor.execute(new Runnable() {

                                @Override
                                public void run() {
                                    // If the node is deleted, attempt the re-election
                                    log.info("Broker [{}] is calling re-election from the thread", pulsar.getWebServiceAddress());
                                    elect();
                                }
                            });
                        }
                        break;
                    default:
                        log.warn("Got something wrong on watch: {}", event);
                        break;
                }
            }
        }, null);
        LeaderBroker leaderBroker = jsonMapper.readValue(data, LeaderBroker.class);
        currentLeader.set(leaderBroker);
        isLeader.set(false);
        leaderListener.brokerIsAFollowerNow();
        // If broker comes here it is a follower. Do nothing, wait for the watch to trigger
        log.info("Broker [{}] is the follower now. Waiting for the watch to trigger...", pulsar.getWebServiceAddress());
    } catch (NoNodeException nne) {
        // There's no leader yet... try to become the leader
        try {
            // Create the root node and add current broker's URL as its contents
            LeaderBroker leaderBroker = new LeaderBroker(pulsar.getWebServiceAddress());
            ZkUtils.createFullPathOptimistic(pulsar.getLocalZkCache().getZooKeeper(), ELECTION_ROOT, jsonMapper.writeValueAsBytes(leaderBroker), Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
            // Update the current leader and set the flag to true
            currentLeader.set(new LeaderBroker(leaderBroker.getServiceUrl()));
            isLeader.set(true);
            // Notify the listener that this broker is now the leader so that it can collect usage and start load
            // manager.
            log.info("Broker [{}] is the leader now, notifying the listener...", pulsar.getWebServiceAddress());
            leaderListener.brokerIsTheLeaderNow();
        } catch (NodeExistsException nee) {
            // Re-elect the new leader
            log.warn("Got exception [{}] while creating election node because it already exists. Attempting re-election...", nee.getMessage());
            executor.execute(new Runnable() {

                @Override
                public void run() {
                    elect();
                }
            });
        } catch (Exception e) {
            // Kill the broker because this broker's session with zookeeper might be stale. Killing the broker will
            // make sure that we get the fresh zookeeper session.
            log.error("Got exception [{}] while creating the election node", e.getMessage());
            pulsar.getShutdownService().shutdown(-1);
        }
    } catch (Exception e) {
        // Kill the broker
        log.error("Could not get the content of [{}], got exception [{}]. Shutting down the broker...", ELECTION_ROOT, e);
        pulsar.getShutdownService().shutdown(-1);
    }
}

Example 28 with Watcher

use of org.apache.zookeeper.Watcher in project yyl_example by Relucent.

the class Test1 method main.

public static void main(String[] args) throws Exception {
    ZooKeeper zk = new ZooKeeper("localhost:2181", 1000, new Watcher() {

        // 监控所有被触发的事件
        public void process(WatchedEvent event) {
            System.out.println("已经触发了" + event.getType() + "事件！");
        }
    });
    // 创建一个目录节点
    zk.create("/testRootPath", "testRootData".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
    // 创建一个子目录节点
    zk.create("/testRootPath/testChildPathOne", "testChildDataOne".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
    System.out.println(new String(zk.getData("/testRootPath", false, null)));
    // 取出子目录节点列表
    System.out.println(zk.getChildren("/testRootPath", true));
    // 修改子目录节点数据
    zk.setData("/testRootPath/testChildPathOne", "modifyChildDataOne".getBytes(), -1);
    System.out.println("目录节点状态：[" + zk.exists("/testRootPath", true) + "]");
    // 创建另外一个子目录节点
    zk.create("/testRootPath/testChildPathTwo", "testChildDataTwo".getBytes(), Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
    System.out.println(new String(zk.getData("/testRootPath/testChildPathTwo", true, null)));
    // 删除子目录节点
    zk.delete("/testRootPath/testChildPathTwo", -1);
    zk.delete("/testRootPath/testChildPathOne", -1);
    // 删除父目录节点
    zk.delete("/testRootPath", -1);
    // 关闭连接
    zk.close();
}

Example 29 with Watcher

use of org.apache.zookeeper.Watcher in project yyl_example by Relucent.

the class Test3 method main.

public static void main(String[] args) {
    ZooKeeper zk = null;
    try {
        zk = new ZooKeeper("localhost:2181", 1000, null);
        zk.exists("/test", new Watcher() {

            @Override
            public void process(WatchedEvent e) {
                System.out.println(e);
            }
        });
        Thread.sleep(60 * 1000);
    } catch (Exception e) {
        e.printStackTrace();
        try {
            if (zk != null) {
                zk.close();
            }
        } catch (Exception e1) {
        }
    }
}

Example 30 with Watcher

use of org.apache.zookeeper.Watcher in project Dempsy by Dempsy.

the class TestZookeeperClusterImpl method testBadZooKeeperConnection.

@Test
public void testBadZooKeeperConnection() throws Throwable {
    int port = ZookeeperTestServer.findNextPort();
    ZookeeperTestServer server = new ZookeeperTestServer();
    Throwable receivedException = null;
    ZookeeperSession session = null;
    try {
        server.start();
        session = new ZookeeperSession("127.0.0.1:" + port, 5000) {

            @Override
            protected ZooKeeper makeZooKeeperClient(String connectString, int sessionTimeout) throws IOException {
                return new ZooKeeper(connectString, sessionTimeout, new ZkWatcher()) {

                    @Override
                    public List<String> getChildren(String path, Watcher watcher) throws KeeperException {
                        throw (appropriateException = new KeeperException(Code.DATAINCONSISTENCY) {

                            private static final long serialVersionUID = 1L;
                        });
                    }
                };
            }
        };
        try {
            session.getSubdirs(new ClusterId("test", "test").asPath(), null);
        } catch (Exception e) {
            receivedException = e.getCause();
        }
    } finally {
        server.shutdown();
        if (session != null)
            session.stop();
    }
    assertNotNull(appropriateException);
    assertTrue(receivedException == appropriateException);
}