Examples of ZooKeeper

com.alipay.bluewhale.core.zk.Zookeeper
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com.linkedin.d2.discovery.stores.zk.ZooKeeper
An interface that abstracts the {@link org.apache.zookeeper.ZooKeeper}. @author Ang Xu @version $Revision: $
org.apache.zookeeper.ZooKeeper
This is the main class of ZooKeeper client library. To use a ZooKeeper service, an application must first instantiate an object of ZooKeeper class. All the iterations will be done by calling the methods of ZooKeeper class.
Once a connection to a server is established, a session ID is assigned to the client. The client will send heart beats to the server periodically to keep the session valid.
The application can call ZooKeeper APIs through a client as long as the session ID of the client remains valid.
If for some reason, the client fails to send heart beats to the server for a prolonged period of time (exceeding the sessionTimeout value, for instance), the server will expire the session, and the session ID will become invalid. The client object will no longer be usable. To make ZooKeeper API calls, the application must create a new client object.
If the ZooKeeper server the client currently connects to fails or otherwise does not respond, the client will automatically try to connect to another server before its session ID expires. If successful, the application can continue to use the client.
Some successful ZooKeeper API calls can leave watches on the "data nodes" in the ZooKeeper server. Other successful ZooKeeper API calls can trigger those watches. Once a watch is triggered, an event will be delivered to the client which left the watch at the first place. Each watch can be triggered only once. Thus, up to one event will be delivered to a client for every watch it leaves.
A client needs an object of a class implementing Watcher interface for processing the events delivered to the client. When a client drops current connection and re-connects to a server, all the existing watches are considered as being triggered but the undelivered events are lost. To emulate this, the client will generate a special event to tell the event handler a connection has been dropped. This special event has type EventNone and state sKeeperStateDisconnected.
org.apache.zookeeper_voltpatches.ZooKeeper
This is the main class of ZooKeeper client library. To use a ZooKeeper service, an application must first instantiate an object of ZooKeeper class. All the iterations will be done by calling the methods of ZooKeeper class. The methods of this class are thread-safe unless otherwise noted.
Once a connection to a server is established, a session ID is assigned to the client. The client will send heart beats to the server periodically to keep the session valid.
The application can call ZooKeeper APIs through a client as long as the session ID of the client remains valid.
If for some reason, the client fails to send heart beats to the server for a prolonged period of time (exceeding the sessionTimeout value, for instance), the server will expire the session, and the session ID will become invalid. The client object will no longer be usable. To make ZooKeeper API calls, the application must create a new client object.
If the ZooKeeper server the client currently connects to fails or otherwise does not respond, the client will automatically try to connect to another server before its session ID expires. If successful, the application can continue to use the client.
Some successful ZooKeeper API calls can leave watches on the "data nodes" in the ZooKeeper server. Other successful ZooKeeper API calls can trigger those watches. Once a watch is triggered, an event will be delivered to the client which left the watch at the first place. Each watch can be triggered only once. Thus, up to one event will be delivered to a client for every watch it leaves.
A client needs an object of a class implementing Watcher interface for processing the events delivered to the client. When a client drops current connection and re-connects to a server, all the existing watches are considered as being triggered but the undelivered events are lost. To emulate this, the client will generate a special event to tell the event handler a connection has been dropped. This special event has type EventNone and state sKeeperStateDisconnected.

Examples of org.apache.zookeeper.ZooKeeper

                    public void run()
                    {
                        if (logger.isTraceEnabled())
                        logger.trace("Executing ZooKeeper client reset.");


                        ZooKeeper newZk = null;
                        try
                        {
                            boolean forceRebuild = false;
                            if (failedInstance.getState().isAlive())
                            {

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Examples of org.apache.zookeeper.ZooKeeper

    {
        if (logger.isTraceEnabled()) logger.trace("reestablished connection to " + connectString);


        if (isRunning)
        {
            final ZooKeeper last = zkref.getAndSet(newZk);
            if (last != null && last != newZk)
            {
                try {
                    last.close();
                } catch (final Throwable th) {}
            }
        }
        else
        {

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Examples of org.apache.zookeeper.ZooKeeper

         assertEquals(0,((MetricGetters)collector).getDiscardedMessageCount());
         assertEquals(0,((MetricGetters)collector).getMessageFailedCount());


         // ok ... so now we have stuff going all the way through. let's kick
         // the middle Mp's zookeeper cluster and see what happens.
         ZooKeeper origZk = zookeeperCluster.zkref.get();
         long sessionid = origZk.getSessionId();
         ZooKeeper killer = new ZooKeeper(System.getProperty("zk_connect"),5000, new Watcher() { @Override public void process(WatchedEvent arg0) { } }, sessionid, null);
         killer.close(); // tricks the server into expiring the other session


//         // we should be getting failures now ... 
//         // but it's possible that it can reconnect prior to actually seeing an error so if this 
//         //   fails frequently we need to remove this test.
//         assertTrue(poll(baseTimeoutMillis, app, new Condition()

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Examples of org.apache.zookeeper.ZooKeeper

         assertEquals(0,((MetricGetters)collector).getDiscardedMessageCount());
         assertEquals(0,((MetricGetters)collector).getMessageFailedCount());


         // ok ... so now we have stuff going all the way through. let's kick
         // the middle Mp's zookeeper cluster and see what happens.
         ZooKeeper origZk = zookeeperCluster.zkref.get();
         origZk.close(); // this should kill it.
         
         // but just to be sure actually stop the node.
         mpnode.stop();


         // we should be getting failures now ... and then recover.

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Examples of org.apache.zookeeper.ZooKeeper

         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)

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Examples of org.apache.zookeeper.ZooKeeper

      while (!done)
      {
         long sessionid = origZk.getSessionId();
         byte[] pw = origZk.getSessionPasswd();
         KWatcher kwatcher = new KWatcher();
         ZooKeeper killer = new ZooKeeper("127.0.0.1:" + port,5000, kwatcher, sessionid, pw);
         kwatcher.connection.set(killer);


         // wait until we get a close
         boolean calledBack = TestUtils.poll(5000, kwatcher, new Condition<KWatcher>()
               {
            @Override
            public boolean conditionMet(KWatcher o) throws Throwable
            {
               return o.closed.get();
            }
               });


         if (!calledBack)
            killer.close(); 


         final AtomicBoolean isExpired = new AtomicBoolean(false);
         ZooKeeper check = new ZooKeeper("127.0.0.1:" + port,5000, new Watcher()
         {
            @Override
            public void process(WatchedEvent event)
            {
               if (event.getState() == Watcher.Event.KeeperState.Expired)
                  isExpired.set(true);
            }
         }, sessionid, pw);
         
         done = TestUtils.poll(5000, isExpired, new Condition<AtomicBoolean>() { public boolean conditionMet(AtomicBoolean o) { return o.get(); } });
         
         check.close();
      }
   }

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Examples of org.apache.zookeeper.ZooKeeper

      AtomicBoolean closed = new AtomicBoolean(false);
      
      @Override
      public void process(final WatchedEvent event)
      {
         final ZooKeeper tcon = connection.get();
         if (tcon != null && event.getState() == Watcher.Event.KeeperState.SyncConnected)
         {
            try { tcon.close(); closed.set(true); } catch (InterruptedException ie) {}
         }
      }

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Examples of org.apache.zookeeper.ZooKeeper

            @Override public boolean conditionMet(TestWatcher o){  return !o.called.get(); }
         }));


         session.getSubdirs(clusterId.asPath(), callback);
         
         ZooKeeper origZk = session.zkref.get();
         ZookeeperTestServer.forceSessionExpiration(origZk);
         
         // wait for the callback
         assertTrue(TestUtils.poll(baseTimeoutMillis, callback, new Condition<TestWatcher>() {
            @Override public boolean conditionMet(TestWatcher o){  return o.called.get(); }

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Examples of org.apache.zookeeper.ZooKeeper

            }
            
         }));


         logger.trace("Killing zookeeper");
         ZooKeeper origZk = session.zkref.get();
         ZookeeperTestServer.forceSessionExpiration(origZk);
         logger.trace("Killed zookeeper");
         
         // wait for the current session to go invalid
         assertTrue(poll(baseTimeoutMillis, origZk, new Condition<ZooKeeper>()

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Examples of org.apache.zookeeper.ZooKeeper

        int retryDelay = 10;


        while (true) {
            try {
                logger.warn("connecting to {}", connectString);
                zk = new ZooKeeper(connectString, 5000, new StateWatcher());
                try {
                    zk.create(base, new byte[0], ZooDefs.Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
                } catch (KeeperException.NodeExistsException e) {
                    // ignore
                }

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