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

Example 56 with Watcher

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

the class ZooKeeperClient method get.

/**
   * 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
   * @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(Amount<Long, Time> 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()) {
                    // 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;
                        }
                }
                eventQueue.offer(event);
            }
        };
        try {
            zooKeeper = (sessionState != null) ? new ZooKeeper(zooKeeperServers, sessionTimeoutMs, watcher, sessionState.sessionId, sessionState.sessionPasswd) : new ZooKeeper(zooKeeperServers, sessionTimeoutMs, watcher);
        } catch (IOException e) {
            throw new ZooKeeperConnectionException("Problem connecting to servers: " + zooKeeperServers, e);
        }
        if (connectionTimeout.getValue() > 0) {
            if (!connected.await(connectionTimeout.as(Time.MILLISECONDS), 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;
}

Example 57 with Watcher

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

the class ZooKeeperMap method addChild.

// TODO(Adam Samet) - Make this use the ZooKeeperNode class.
private void addChild(final String child) throws InterruptedException, KeeperException, ZooKeeperConnectionException {
    final Watcher nodeWatcher = new Watcher() {

        @Override
        public void process(WatchedEvent event) {
            if (event.getType() == Watcher.Event.EventType.NodeDataChanged) {
                try {
                    tryAddChild(child);
                } catch (InterruptedException e) {
                    LOG.log(Level.WARNING, "Interrupted while trying to add a child.", e);
                    Thread.currentThread().interrupt();
                }
            } else if (event.getType() == Watcher.Event.EventType.NodeDeleted) {
                removeEntry(child);
            }
        }
    };
    try {
        V value = deserializer.apply(zkClient.get().getData(makePath(child), nodeWatcher, null));
        putEntry(child, value);
    } catch (KeeperException.NoNodeException e) {
        // This node doesn't exist anymore, remove it from the map and we're done.
        removeEntry(child);
    }
}

Example 58 with Watcher

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

the class ZooKeeperMap method watchChildren.

private synchronized void watchChildren() throws InterruptedException, KeeperException, ZooKeeperConnectionException {
    /*
     * Add a watch on the parent node itself, and attempt to rewatch if it
     * gets deleted
     */
    zkClient.get().exists(nodePath, new Watcher() {

        @Override
        public void process(WatchedEvent event) {
            if (event.getType() == Watcher.Event.EventType.NodeDeleted) {
                // If the parent node no longer exists
                localMap.clear();
                try {
                    tryWatchChildren();
                } catch (InterruptedException e) {
                    LOG.log(Level.WARNING, "Interrupted while trying to watch children.", e);
                    Thread.currentThread().interrupt();
                }
            }
        }
    });
    final Watcher childWatcher = new Watcher() {

        @Override
        public void process(WatchedEvent event) {
            if (event.getType() == Watcher.Event.EventType.NodeChildrenChanged) {
                try {
                    tryWatchChildren();
                } catch (InterruptedException e) {
                    LOG.log(Level.WARNING, "Interrupted while trying to watch children.", e);
                    Thread.currentThread().interrupt();
                }
            }
        }
    };
    List<String> children = zkClient.get().getChildren(nodePath, childWatcher);
    updateChildren(Sets.newHashSet(children));
}

Example 59 with Watcher

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

the class ZooKeeperMap method init.

/**
   * Initialize zookeeper tracking for this {@link Map}.  Once this call returns, this object
   * will be tracking data in zookeeper.
   *
   * @throws InterruptedException if the underlying zookeeper server transaction is interrupted
   * @throws KeeperException if the server signals an error
   * @throws ZooKeeperConnectionException if there was a problem connecting to the zookeeper
   *     cluster
   */
@VisibleForTesting
void init() throws InterruptedException, KeeperException, ZooKeeperConnectionException {
    Watcher watcher = zkClient.registerExpirationHandler(new Command() {

        @Override
        public void execute() {
            /*
         * First rewatch all of our locally cached children.  Some of them may not exist anymore,
         * which will lead to caught KeeperException.NoNode whereafter we'll remove that child
         * from the cached map.
         *
         * Next, we'll establish our top level child watch and add any new nodes that might exist.
         */
            try {
                synchronized (safeToRewatchLock) {
                    if (safeToRewatch) {
                        rewatchDataNodes();
                        tryWatchChildren();
                    }
                }
            } catch (InterruptedException e) {
                LOG.log(Level.WARNING, "Interrupted while trying to re-establish watch.", e);
                Thread.currentThread().interrupt();
            }
        }
    });
    try {
        // before we update safeToRewatch.
        synchronized (safeToRewatchLock) {
            watchChildren();
            safeToRewatch = true;
        }
    } catch (InterruptedException e) {
        zkClient.unregister(watcher);
        throw e;
    } catch (KeeperException e) {
        zkClient.unregister(watcher);
        throw e;
    } catch (ZooKeeperConnectionException e) {
        zkClient.unregister(watcher);
        throw e;
    }
}

Example 60 with Watcher

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

the class TestZooKeeperClient method expireZooKeeperSession.

private void expireZooKeeperSession(ZooKeeper zk, int timeout) throws IOException, InterruptedException, KeeperException {
    final CountDownLatch latch = new CountDownLatch(1);
    ZooKeeper newZk = new ZooKeeper(zkServers, timeout, new Watcher() {

        @Override
        public void process(WatchedEvent event) {
            if (event.getType() == EventType.None && event.getState() == KeeperState.SyncConnected) {
                latch.countDown();
            }
        }
    }, zk.getSessionId(), zk.getSessionPasswd());
    if (!latch.await(timeout, TimeUnit.MILLISECONDS)) {
        throw KeeperException.create(KeeperException.Code.CONNECTIONLOSS);
    }
    newZk.close();
}