Java ZkClient.subscribeChildChanges方法代码示例

import org.apache.helix.manager.zk.ZkClient; //导入方法依赖的package包/类
public void start(ControllerMetrics controllerMetrics) {
  _controllerMetrics = controllerMetrics;

  LOGGER.info("Starting realtime segments manager, adding a listener on the property store table configs path.");
  String zkUrl = _pinotHelixResourceManager.getHelixZkURL();
  _zkClient = new ZkClient(zkUrl, ZkClient.DEFAULT_SESSION_TIMEOUT, ZkClient.DEFAULT_CONNECTION_TIMEOUT);
  _zkClient.setZkSerializer(new ZNRecordSerializer());
  _zkClient.waitUntilConnected();

  // Subscribe to any data/child changes to property
  _zkClient.subscribeChildChanges(_tableConfigPath, this);
  _zkClient.subscribeDataChanges(_tableConfigPath, this);

  // Subscribe to leadership changes
  _pinotHelixResourceManager.getHelixZkManager().addControllerListener(new ControllerChangeListener() {
    @Override
    public void onControllerChange(NotificationContext changeContext) {
      processPropertyStoreChange(CONTROLLER_LEADER_CHANGE);
    }
  });

  // Setup change listeners for already existing tables, if any.
  processPropertyStoreChange(_tableConfigPath);
}
 

import org.apache.helix.manager.zk.ZkClient; //导入方法依赖的package包/类
/**
 * test zk watchers are renewed automatically after session expiry
 * zookeeper-client side keeps all registered watchers see ZooKeeper.WatchRegistration.register()
 * after session expiry, all watchers are renewed
 * if a path that has watches on it has been removed during session expiry,
 * the watchers on that path will still get callbacks after session renewal, especially:
 * a data-watch will get data-deleted callback
 * a child-watch will get a child-change callback with current-child-list = null
 * this can be used for cleanup watchers on the zookeeper-client side
 */
@Test
public void testWatchRenew() throws Exception {

  String className = TestHelper.getTestClassName();
  String methodName = TestHelper.getTestMethodName();
  String testName = className + "_" + methodName;

  final ZkClient client =
      new ZkClient(ZK_ADDR, ZkClient.DEFAULT_SESSION_TIMEOUT,
          ZkClient.DEFAULT_CONNECTION_TIMEOUT, new ZNRecordSerializer());
  // make sure "/testName/test" doesn't exist
  final String path = "/" + testName + "/test";
  client.delete(path);

  ZkListener listener = new ZkListener();
  client.subscribeDataChanges(path, listener);
  client.subscribeChildChanges(path, listener);

  ZkTestHelper.expireSession(client);

  boolean succeed = listener._childChangeCountDown.await(10, TimeUnit.SECONDS);
  Assert.assertTrue(succeed,
      "fail to wait on child-change count-down in 10 seconds after session-expiry");
  Assert.assertEquals(listener._parentPath, path,
      "fail to get child-change callback after session-expiry");
  Assert.assertNull(listener._currentChilds,
      "fail to get child-change callback with currentChilds=null after session expiry");

  succeed = listener._dataDeleteCountDown.await(10, TimeUnit.SECONDS);
  Assert.assertTrue(succeed,
      "fail to wait on data-delete count-down in 10 seconds after session-expiry");
  Assert.assertEquals(listener._dataDeletePath, path,
      "fail to get data-delete callback after session-expiry");

  client.close();
}
 

import org.apache.helix.manager.zk.ZkClient; //导入方法依赖的package包/类
/**
 * after calling zkclient#unsubscribeXXXListener()
 * an already registered watch will not be removed from ZooKeeper#watchManager#XXXWatches
 * immediately.
 * the watch will get removed on the following conditions:
 * 1) there is a set/delete on the listening path via the zkclient
 * 2) session expiry on the zkclient (i.e. the watch will not be renewed after session expiry)
 * @throws Exception
 */
@Test
public void testWatchRemove() throws Exception {
  String className = TestHelper.getTestClassName();
  String methodName = TestHelper.getTestMethodName();
  String testName = className + "_" + methodName;

  final ZkClient client =
      new ZkClient(ZK_ADDR, ZkClient.DEFAULT_SESSION_TIMEOUT,
          ZkClient.DEFAULT_CONNECTION_TIMEOUT, new ZNRecordSerializer());
  // make sure "/testName/test" doesn't exist
  final String path = "/" + testName + "/test";
  client.createPersistent(path, true);

  ZkListener listener = new ZkListener();
  client.subscribeDataChanges(path, listener);
  client.subscribeChildChanges(path, listener);

  // listener should be in both ZkClient#_dataListener and ZkClient#_childListener set
  Map<String, Set<IZkDataListener>> dataListenerMap = ZkTestHelper.getZkDataListener(client);
  Assert.assertEquals(dataListenerMap.size(), 1, "ZkClient#_dataListener should have 1 listener");
  Set<IZkDataListener> dataListenerSet = dataListenerMap.get(path);
  Assert.assertNotNull(dataListenerSet, "ZkClient#_dataListener should have 1 listener on path: "
      + path);
  Assert.assertEquals(dataListenerSet.size(), 1,
      "ZkClient#_dataListener should have 1 listener on path: " + path);

  Map<String, Set<IZkChildListener>> childListenerMap = ZkTestHelper.getZkChildListener(client);
  Assert.assertEquals(childListenerMap.size(), 1,
      "ZkClient#_childListener should have 1 listener");
  Set<IZkChildListener> childListenerSet = childListenerMap.get(path);
  Assert.assertNotNull(childListenerSet,
      "ZkClient#_childListener should have 1 listener on path: " + path);
  Assert.assertEquals(childListenerSet.size(), 1,
      "ZkClient#_childListener should have 1 listener on path: " + path);

  // watch should be in ZooKeeper#watchManager#XXXWatches
  Map<String, List<String>> watchMap = ZkTestHelper.getZkWatch(client);
  // System.out.println("watchMap1: " + watchMap);
  List<String> dataWatch = watchMap.get("dataWatches");
  Assert.assertNotNull(dataWatch,
      "ZooKeeper#watchManager#dataWatches should have 1 data watch on path: " + path);
  Assert.assertEquals(dataWatch.size(), 1,
      "ZooKeeper#watchManager#dataWatches should have 1 data watch on path: " + path);
  Assert.assertEquals(dataWatch.get(0), path,
      "ZooKeeper#watchManager#dataWatches should have 1 data watch on path: " + path);

  List<String> childWatch = watchMap.get("childWatches");
  Assert.assertNotNull(childWatch,
      "ZooKeeper#watchManager#childWatches should have 1 child watch on path: " + path);
  Assert.assertEquals(childWatch.size(), 1,
      "ZooKeeper#watchManager#childWatches should have 1 child watch on path: " + path);
  Assert.assertEquals(childWatch.get(0), path,
      "ZooKeeper#watchManager#childWatches should have 1 child watch on path: " + path);

  client.unsubscribeDataChanges(path, listener);
  client.unsubscribeChildChanges(path, listener);
  // System.out.println("watchMap2: " + watchMap);
  ZkTestHelper.expireSession(client);

  // after session expiry, those watches should be removed
  watchMap = ZkTestHelper.getZkWatch(client);
  // System.out.println("watchMap3: " + watchMap);
  dataWatch = watchMap.get("dataWatches");
  Assert.assertTrue(dataWatch.isEmpty(), "ZooKeeper#watchManager#dataWatches should be empty");
  childWatch = watchMap.get("childWatches");
  Assert.assertTrue(childWatch.isEmpty(), "ZooKeeper#watchManager#childWatches should be empty");

  client.close();
}