Example usage for org.apache.zookeeper WatchedEvent getType

Introduction

In this page you can find the example usage for org.apache.zookeeper WatchedEvent getType.

Prototype

public EventType getType() 

Source Link

Usage

From source file:com.twitter.finagle.common.zookeeper.ZooKeeperClient.java

License:Apache License

/**
 * Returns the current active ZK connection or establishes a new one if none has yet been
 * established or a previous connection was disconnected or had its session time out.  This
 * method will attempt to re-use sessions when possible.
 *
 * @param connectionTimeout the maximum amount of time to wait for the connection to the ZK
 *     cluster to be established; 0 to wait forever
 * @return a connected ZooKeeper client/*  ww w  .j a v a2  s  . c o m*/
 * @throws ZooKeeperConnectionException if there was a problem connecting to the ZK cluster
 * @throws InterruptedException if interrupted while waiting for a connection to be established
 * @throws TimeoutException if a connection could not be established within the configured
 *     session timeout
 */
public synchronized ZooKeeper get(Duration connectionTimeout)
        throws ZooKeeperConnectionException, InterruptedException, TimeoutException {

    if (zooKeeper == null) {
        final CountDownLatch connected = new CountDownLatch(1);
        Watcher watcher = new Watcher() {
            @Override
            public void process(WatchedEvent event) {
                switch (event.getType()) {
                // Guard the None type since this watch may be used as the default watch on calls by
                // the client outside our control.
                case None:
                    switch (event.getState()) {
                    case Expired:
                        LOG.info("Zookeeper session expired. Event: " + event);
                        close();
                        break;
                    case SyncConnected:
                        connected.countDown();
                        break;
                    default:
                        break; // nop
                    }
                    break;
                default:
                    break; // nop
                }

                eventQueue.offer(event);
            }
        };

        try {
            zooKeeper = (sessionState != null)
                    ? new ZooKeeper(connectString, sessionTimeoutMs, watcher, sessionState.sessionId,
                            sessionState.sessionPasswd)
                    : new ZooKeeper(connectString, sessionTimeoutMs, watcher);
        } catch (IOException e) {
            throw new ZooKeeperConnectionException("Problem connecting to servers: " + zooKeeperServers, e);
        }

        if (connectionTimeout.inMillis() > 0) {
            if (!connected.await(connectionTimeout.inMillis(), TimeUnit.MILLISECONDS)) {
                close();
                throw new TimeoutException("Timed out waiting for a ZK connection after " + connectionTimeout);
            }
        } else {
            try {
                connected.await();
            } catch (InterruptedException ex) {
                LOG.info("Interrupted while waiting to connect to zooKeeper");
                close();
                throw ex;
            }
        }
        credentials.authenticate(zooKeeper);

        sessionState = new SessionState(zooKeeper.getSessionId(), zooKeeper.getSessionPasswd());
    }
    return zooKeeper;
}

---

From source file:com.twitter.finagle.common.zookeeper.ZooKeeperClient.java

License:Apache License

/**
 * Clients that need to re-establish state after session expiration can register an
 * {@code onExpired} command to execute.
 *
 * @param onExpired the {@code Runnable} to register
 * @return the new {@link Watcher} which can later be passed to {@link #unregister} for
 *     removal./* w w w  . jav  a2  s.c  om*/
 */
public Watcher registerExpirationHandler(final Runnable onExpired) {
    Watcher watcher = new Watcher() {
        @Override
        public void process(WatchedEvent event) {
            if (event.getType() == EventType.None && event.getState() == KeeperState.Expired) {
                onExpired.run();
            }
        }
    };
    register(watcher);
    return watcher;
}

---

From source file:com.twitter.heron.statemgr.zookeeper.ZkWatcherCallback.java

License:Open Source License

public static Watcher makeZkWatcher(final WatchCallback watcher) {
    return watcher == null ? null : new Watcher() {
        @Override//  w  ww. j ava2  s .  c o  m
        public void process(WatchedEvent watchedEvent) {
            WatchCallback.WatchEventType watchEventType;
            switch (watchedEvent.getType()) {
            case None:
                watchEventType = WatchCallback.WatchEventType.None;
                break;
            case NodeCreated:
                watchEventType = WatchCallback.WatchEventType.NodeCreated;
                break;
            case NodeDeleted:
                watchEventType = WatchCallback.WatchEventType.NodeDeleted;
                break;
            case NodeDataChanged:
                watchEventType = WatchCallback.WatchEventType.NodeDataChanged;
                break;
            case NodeChildrenChanged:
                watchEventType = WatchCallback.WatchEventType.NodeChildrenChanged;
                break;

            default:
                throw new RuntimeException("Invalid integer value for conversion to EventType");
            }
            watcher.processWatch(watchedEvent.getPath(), watchEventType);
        }
    };
}

---

From source file:com.vmware.photon.controller.common.zookeeper.DataDictionary.java

License:Open Source License

/**
 * Reads and returns ZK node {basePath}/{key} value, optionally setting up a one-time callback for the data change.
 *
 * @param key             Key to read/*from w  w  w.jav a 2s. c  o  m*/
 * @param changeListener  Callback that gets called when node data has changed. Will only be called once
 * @param notifyWhenAdded If true, watch will be set if the node is missing and fire once it's created
 * @return Node data or null if key doesn't exist yet
 * @throws Exception
 */
public byte[] read(final String key, final ChangeListener changeListener, boolean notifyWhenAdded)
        throws Exception {
    final String nodePath = ZKPaths.makePath(basePath, key);

    CuratorWatcher watcher = new CuratorWatcher() {
        @Override
        public void process(final WatchedEvent event) throws Exception {
            executor.submit(new Runnable() {
                @Override
                public void run() {
                    if (event.getType() == Watcher.Event.EventType.NodeDataChanged) {
                        changeListener.onDataChanged(key);
                    } else if (event.getType() == Watcher.Event.EventType.NodeDeleted) {
                        changeListener.onKeyRemoved(key);
                    } else if (event.getType() == Watcher.Event.EventType.NodeCreated) {
                        changeListener.onKeyAdded(key);
                    }
                }
            });
        }
    };

    try {
        if (changeListener != null) {
            return zkClient.getData().usingWatcher(watcher).forPath(nodePath);
        } else {
            return zkClient.getData().forPath(nodePath);
        }
    } catch (KeeperException.NoNodeException e) {
        if (changeListener != null && notifyWhenAdded) {
            zkClient.checkExists().usingWatcher(watcher).forPath(nodePath);
        }
        return null;
    }
}

---

From source file:com.yahoo.pasc.paxos.Barrier.java

License:Open Source License

@Override
public void process(org.apache.zookeeper.WatchedEvent event) {
    if (event.getType().equals(EventType.NodeChildrenChanged)
            || event.getType().equals(EventType.NodeCreated)) {
        synchronized (mutex) {
            mutex.notify();//from  w  w w.jav  a  2 s . c o m
        }
    }
}

---

From source file:com.yahoo.pulsar.broker.loadbalance.LeaderElectionService.java

License:Apache License

/**
 * 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.
 *//*w  ww . j a v  a 2 s  .  c om*/
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);
    }
}

---

From source file:com.yahoo.pulsar.zookeeper.GlobalZooKeeperCache.java

License:Apache License

@Override
public <T> void process(WatchedEvent event, final CacheUpdater<T> updater) {
    synchronized (this) {
        if (LOG.isDebugEnabled()) {
            LOG.debug("[{}] Got Global ZooKeeper WatchdEvent: EventType: {}, KeeperState: {}, path: {}",
                    this.hashCode(), event.getType(), event.getState(), event.getPath());
        }//from   w  w w .  j  av  a  2 s  .  c o  m
        if (event.getType() == Event.EventType.None) {
            switch (event.getState()) {
            case Expired:
                // in case of expired, the zkSession is no longer good for sure.
                // We need to restart the session immediately.
                // cancel any timer event since it is already bad
                ZooKeeper oldSession = this.zkSession.getAndSet(null);
                LOG.warn("Global ZK session lost. Triggering reconnection {}", oldSession);
                safeCloseZkSession(oldSession);
                asyncRestartZooKeeperSession();
                return;
            case SyncConnected:
            case ConnectedReadOnly:
                checkNotNull(zkSession.get());
                LOG.info("Global ZK session {} restored connection.", zkSession.get());

                //
                dataCache.synchronous().invalidateAll();
                childrenCache.invalidateAll();
                return;
            default:
                break;
            }
        }
    }

    // Other types of events
    super.process(event, updater);

}

---

From source file:com.yahoo.pulsar.zookeeper.LocalZooKeeperCache.java

License:Apache License

@Override
public <T> void process(WatchedEvent event, final CacheUpdater<T> updater) {
    if (LOG.isDebugEnabled()) {
        LOG.debug("Got Local ZooKeeper WatchedEvent: EventType: {}, KeeperState: {}, Path: {}", event.getType(),
                event.getState(), event.getPath());
    }/*from w w  w.  j a va2  s .  c  om*/
    if (event.getType() == Event.EventType.None) {
        switch (event.getState()) {
        case Expired:
            // in case of expired, the zkSession is no longer good
            LOG.warn("Lost connection from local ZK. Invalidating the whole cache.");
            dataCache.synchronous().invalidateAll();
            childrenCache.invalidateAll();
            return;
        default:
            break;
        }
    }
    super.process(event, updater);
}

---

From source file:com.yahoo.pulsar.zookeeper.ZooKeeperSessionWatcher.java

License:Apache License

@Override
public void process(WatchedEvent event) {
    Watcher.Event.EventType eventType = event.getType();
    Watcher.Event.KeeperState eventState = event.getState();

    LOG.info("Received zookeeper notification, eventType={}, eventState={}", eventType, eventState);

    switch (eventType) {
    case None:/*  ww  w  . j a va 2 s .c om*/
        if (eventState == Watcher.Event.KeeperState.Expired) {
            LOG.error("ZooKeeper session already expired, invoking shutdown");
            close();
            shuttingDown = true;
            shutdownService.shutdown(-1);
        }
        break;
    default:
        break;
    }

}

---

From source file:com.yihaodian.architecture.zkclient.ZkClient.java

License:Apache License

public void process(WatchedEvent event) {
    LOG.debug("Received event: " + event);
    _zookeeperEventThread = Thread.currentThread();

    boolean stateChanged = event.getPath() == null;
    boolean znodeChanged = event.getPath() != null;
    boolean dataChanged = event.getType() == EventType.NodeDataChanged
            || event.getType() == EventType.NodeDeleted || event.getType() == EventType.NodeCreated
            || event.getType() == EventType.NodeChildrenChanged;

    getEventLock().lock();//ww  w .  j a v  a 2s.co m
    try {

        // We might have to install child change event listener if a new
        // node was created
        if (getShutdownTrigger()) {
            LOG.debug("ignoring event '{" + event.getType() + " | " + event.getPath()
                    + "}' since shutdown triggered");
            return;
        }
        if (stateChanged) {
            processStateChanged(event);
        }
        if (dataChanged) {
            processDataOrChildChange(event);
        }
    } finally {
        if (stateChanged) {
            getEventLock().getStateChangedCondition().signalAll();

            // If the session expired we have to signal all conditions,
            // because watches might have been removed and
            // there is no guarantee that those
            // conditions will be signaled at all after an Expired event
            // TODO PVo write a test for this
            if (event.getState() == KeeperState.Expired) {
                getEventLock().getZNodeEventCondition().signalAll();
                getEventLock().getDataChangedCondition().signalAll();
                // We also have to notify all listeners that something might
                // have changed
                fireAllEvents();
            }
        }
        if (znodeChanged) {
            getEventLock().getZNodeEventCondition().signalAll();
        }
        if (dataChanged) {
            getEventLock().getDataChangedCondition().signalAll();
        }
        getEventLock().unlock();
        LOG.debug("Leaving process event");
    }
}

---

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