Examples with IZkDataListener org.I0Itec.zkclient.IZkDataListener used on opensource projects

Example 6 with IZkDataListener

use of org.I0Itec.zkclient.IZkDataListener in project samza by apache.

the class TestZkLeaderElector method testLeaderFailure.

/**
   * Tests that Leader Failure automatically promotes the next successor to become the leader
   */
@Test
public void testLeaderFailure() {
    /**
     * electionLatch and count together verify that:
     * 1. the registered listeners are actually invoked by the ZkClient on the correct path
     * 2. for a single participant failure, at-most 1 other participant is notified
     */
    final CountDownLatch electionLatch = new CountDownLatch(1);
    final AtomicInteger count = new AtomicInteger(0);
    BooleanResult isLeader1 = new BooleanResult();
    BooleanResult isLeader2 = new BooleanResult();
    BooleanResult isLeader3 = new BooleanResult();
    // Processor-1
    ZkUtils zkUtils1 = getZkUtilsWithNewClient();
    zkUtils1.registerProcessorAndGetId(new ProcessorData("processor1", "1"));
    ZkLeaderElector leaderElector1 = new ZkLeaderElector("processor1", zkUtils1, new IZkDataListener() {

        @Override
        public void handleDataChange(String dataPath, Object data) throws Exception {
        }

        @Override
        public void handleDataDeleted(String dataPath) throws Exception {
            count.incrementAndGet();
        }
    });
    leaderElector1.setLeaderElectorListener(() -> isLeader1.res = true);
    // Processor-2
    ZkUtils zkUtils2 = getZkUtilsWithNewClient();
    final String path2 = zkUtils2.registerProcessorAndGetId(new ProcessorData("processor2", "2"));
    ZkLeaderElector leaderElector2 = new ZkLeaderElector("processor2", zkUtils2, new IZkDataListener() {

        @Override
        public void handleDataChange(String dataPath, Object data) throws Exception {
        }

        @Override
        public void handleDataDeleted(String dataPath) throws Exception {
            String registeredIdStr = ZkKeyBuilder.parseIdFromPath(path2);
            Assert.assertNotNull(registeredIdStr);
            String predecessorIdStr = ZkKeyBuilder.parseIdFromPath(dataPath);
            Assert.assertNotNull(predecessorIdStr);
            try {
                int selfId = Integer.parseInt(registeredIdStr);
                int predecessorId = Integer.parseInt(predecessorIdStr);
                Assert.assertEquals(1, selfId - predecessorId);
            } catch (Exception e) {
                LOG.error(e.getLocalizedMessage());
            }
            count.incrementAndGet();
            electionLatch.countDown();
        }
    });
    leaderElector2.setLeaderElectorListener(() -> isLeader2.res = true);
    // Processor-3
    ZkUtils zkUtils3 = getZkUtilsWithNewClient();
    zkUtils3.registerProcessorAndGetId(new ProcessorData("processor3", "3"));
    ZkLeaderElector leaderElector3 = new ZkLeaderElector("processor3", zkUtils3, new IZkDataListener() {

        @Override
        public void handleDataChange(String dataPath, Object data) throws Exception {
        }

        @Override
        public void handleDataDeleted(String dataPath) throws Exception {
            count.incrementAndGet();
        }
    });
    leaderElector3.setLeaderElectorListener(() -> isLeader3.res = true);
    // Join Leader Election
    leaderElector1.tryBecomeLeader();
    leaderElector2.tryBecomeLeader();
    leaderElector3.tryBecomeLeader();
    Assert.assertTrue(TestZkUtils.testWithDelayBackOff(() -> isLeader1.res, 2, 100));
    Assert.assertFalse(TestZkUtils.testWithDelayBackOff(() -> isLeader2.res, 2, 100));
    Assert.assertFalse(TestZkUtils.testWithDelayBackOff(() -> isLeader3.res, 2, 100));
    Assert.assertTrue(leaderElector1.amILeader());
    Assert.assertFalse(leaderElector2.amILeader());
    Assert.assertFalse(leaderElector3.amILeader());
    List<String> currentActiveProcessors = zkUtils1.getSortedActiveProcessorsZnodes();
    Assert.assertEquals(3, currentActiveProcessors.size());
    // Leader Failure
    zkUtils1.close();
    currentActiveProcessors.remove(0);
    try {
        Assert.assertTrue(electionLatch.await(5, TimeUnit.SECONDS));
    } catch (InterruptedException e) {
        Assert.fail("Interrupted while waiting for leaderElection listener callback to complete!");
    }
    Assert.assertEquals(1, count.get());
    Assert.assertEquals(currentActiveProcessors, zkUtils2.getSortedActiveProcessorsZnodes());
    // Clean up
    zkUtils2.close();
    zkUtils3.close();
}

Example 7 with IZkDataListener

use of org.I0Itec.zkclient.IZkDataListener in project samza by apache.

the class TestZkUtils method testSubscribeToJobModelVersionChange.

@Test
public void testSubscribeToJobModelVersionChange() {
    ZkKeyBuilder keyBuilder = new ZkKeyBuilder("test");
    String root = keyBuilder.getRootPath();
    zkClient.deleteRecursive(root);
    class Result {

        String res = "";

        public String getRes() {
            return res;
        }

        public void updateRes(String newRes) {
            res = newRes;
        }
    }
    Assert.assertFalse(zkUtils.exists(root));
    // create the paths
    zkUtils.makeSurePersistentPathsExists(new String[] { root, keyBuilder.getJobModelVersionPath(), keyBuilder.getProcessorsPath() });
    Assert.assertTrue(zkUtils.exists(root));
    Assert.assertTrue(zkUtils.exists(keyBuilder.getJobModelVersionPath()));
    Assert.assertTrue(zkUtils.exists(keyBuilder.getProcessorsPath()));
    final Result res = new Result();
    // define the callback
    IZkDataListener dataListener = new IZkDataListener() {

        @Override
        public void handleDataChange(String dataPath, Object data) throws Exception {
            res.updateRes((String) data);
        }

        @Override
        public void handleDataDeleted(String dataPath) throws Exception {
            Assert.fail("Data wasn't deleted;");
        }
    };
    // subscribe
    zkClient.subscribeDataChanges(keyBuilder.getJobModelVersionPath(), dataListener);
    zkClient.subscribeDataChanges(keyBuilder.getProcessorsPath(), dataListener);
    // update
    zkClient.writeData(keyBuilder.getJobModelVersionPath(), "newVersion");
    // verify
    Assert.assertTrue(testWithDelayBackOff(() -> "newVersion".equals(res.getRes()), 2, 1000));
    // update again
    zkClient.writeData(keyBuilder.getProcessorsPath(), "newProcessor");
    Assert.assertTrue(testWithDelayBackOff(() -> "newProcessor".equals(res.getRes()), 2, 1000));
}