Example usage for org.apache.zookeeper Watcher Watcher

Introduction

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

Prototype

Watcher

Source Link

Usage

From source file:com.cloudera.flume.master.TestZKClient.java

License:Apache License

/**
 * Tests bringing up and shutting down a standalone ZooKeeper instance
 *//* w w  w  .j  a v a2 s.c  o m*/
@Test
public void testStandaloneUpAndDown() throws Exception {
    ZKInProcessServer zk = new ZKInProcessServer(2181, "/tmp/flume-test-zk/");
    zk.start();
    ZooKeeper client = new ZooKeeper("localhost:2181", 5000, new Watcher() {
        public void process(WatchedEvent event) {
        }
    });

    Thread.sleep(1000);
    List<String> children = client.getChildren("/", false);
    LOG.warn("Got " + children.size() + " children");
    assertTrue(children.size() > 0);
    zk.stop();
}

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From source file:com.cloudera.flume.master.ZKClient.java

License:Apache License

/**
 * Establishes a connection with a cluster of ZooKeeper servers. Throws an
 * IOException on failure.//from   w ww .  j  a  v  a2s  . c  om
 */
public synchronized boolean init(final InitCallback initCallback) throws IOException {
    Preconditions.checkState(this.zk == null, "zk not null in ZKClient.init");
    initCallBack = initCallback;
    final Retryable retry = new Retryable() {
        public boolean doTry() throws Exception {
            // Wait on this latch for a connection to complete
            // It's important that every try gets its own latch
            final CountDownLatch latch = new CountDownLatch(1);
            final Watcher watcher = new Watcher() {
                public void process(WatchedEvent event) {
                    // Don't down the latch if we weren't the most recent attempt
                    if (event.getState() == KeeperState.SyncConnected) {
                        latch.countDown();
                    }
                }
            };

            zk = new ZooKeeper(hosts, 5000, watcher);

            if (!latch.await(5, TimeUnit.SECONDS)) {
                throw new IOException("Could not connect to ZooKeeper!");
            }
            if (initCallback != null) {
                initCallback.success(ZKClient.this);
            }
            return true;
        };
    };
    RetryHarness harness = new RetryHarness(retry, new FixedRetryPolicy(3), true);

    try {
        return harness.attempt();
    } catch (IOException i) {
        throw i;
    } catch (Exception e) {
        throw new IOException("Unexpected exception connecting to ZK", e);
    }
}

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From source file:com.comcast.viper.flume2storm.location.DynamicLocationService.java

License:Apache License

/**
 * Updates the list of active {@link ServiceProvider} servers, and sets a
 * watch so that we get notified if the list changes
 *///  w  ww  .  j a v a2 s .co  m
protected synchronized void getServiceInstances() {
    if (!zkClient.getState().isConnected()) {
        return;
    }
    final Watcher watcher = new Watcher() {
        @Override
        public void process(final WatchedEvent event) {
            LOG.debug("Service node watch triggered with event: {}", event);
            getServiceInstances();
        }
    };
    try {
        final List<String> res = new ZkOperation(zkClient, servicePath).getChildren(watcher);
        final Collection<SP> newList = new ArrayList<SP>();
        for (final String child : res) {
            final String childPath = ZkUtilies.buildZkPath(servicePath, child);
            try {
                final byte[] bytes = new ZkOperation(zkClient, childPath).getData();
                newList.add(serviceProviderSerialization.deserialize(bytes));
            } catch (final KeeperException.NoNodeException nne) {
                // Programming note: The node was removed been the time we
                // got the
                // list and the parsing time... no big deal
                LOG.debug("znode {} disappear: {}", childPath, nne.getLocalizedMessage());
            } catch (final Exception e) {
                LOG.warn("Failed to deserialize znode " + childPath, e);
            }
        }
        serviceProviderManager.set(newList);
    } catch (final Exception e) {
        if (zkClient.getState().isConnected()) {
            LOG.error("Failed to get service instances", e);
        }
        // Otherwise, we might have a clue why this is failing! :)
    }
}

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From source file:com.consol.citrus.zookeeper.client.ZooClient.java

License:Apache License

private Watcher getConnectionWatcher() {
    return new Watcher() {
        @Override/*from  w ww  .  jav a2  s .  c om*/
        public void process(WatchedEvent event) {
            LOG.debug(String.format("Connection Event: %s", event.toString()));
        }
    };
}

---

From source file:com.continuuity.loom.common.zookeeper.LeaderElection.java

License:Apache License

private Watcher wrapWatcher(final Watcher watcher) {
    return new Watcher() {
        @Override/*from w  w  w  .  j a  va  2 s  . c om*/
        public void process(final WatchedEvent event) {
            executor.execute(new Runnable() {
                @Override
                public void run() {
                    watcher.process(event);
                }
            });
        }
    };
}

---

From source file:com.continuuity.loom.common.zookeeper.lib.ZKInterProcessReentrantLock.java

License:Apache License

public void acquire() {
    if (isOwnerOfLock()) {
        return;//from  w  w  w .j  a  v a2s .  co  m
    }

    // The algo is the following:
    // 1) we add sequential ephemeral node
    // 2a) if added node is the first one in the list, we acquired the lock. Finish
    // 2b) if added node is not the first one, then add watch to the one before it to re-acquire when it is deleted.

    lockNode = Futures.getUnchecked(zkClient.create(lockPath, null, CreateMode.EPHEMERAL_SEQUENTIAL, true));
    NodeChildren nodeChildren = Futures.getUnchecked(zkClient.getChildren(path));
    List<String> children = nodeChildren.getChildren();
    Collections.sort(children);
    if (lockNode.equals(path + "/" + children.get(0))) {
        // we are the first to acquire the lock
        return;
    }

    final SettableFuture<Object> future = SettableFuture.create();
    boolean setWatcher = false;
    // add watch to the previous node
    Collections.reverse(children);
    for (String child : children) {
        child = path + "/" + child;
        if (child.compareTo(lockNode) < 0) {
            OperationFuture<Stat> exists = zkClient.exists(child, new Watcher() {
                @Override
                public void process(WatchedEvent event) {
                    if (event.getType() == Event.EventType.NodeDeleted) {
                        future.set(new Object());
                    }
                }
            });
            // if it was deleted before we managed to add watcher, we need to add watcher to the current previous, hence
            // continue looping
            if (Futures.getUnchecked(exists) != null) {
                setWatcher = true;
                break;
            }
        }
    }

    if (!setWatcher) {
        // we are owners of a lock, just return
        return;
    }

    // wait for lock to be released by previous owner
    Futures.getUnchecked(future);
}

---

From source file:com.continuuity.weave.internal.AbstractZKServiceController.java

License:Apache License

private void actOnExists(final String path, final Runnable action) {
    // Watch for node existence.
    final AtomicBoolean nodeExists = new AtomicBoolean(false);
    Futures.addCallback(zkClient.exists(path, new Watcher() {
        @Override// w  w  w  .  j a  v a  2  s.  c o m
        public void process(WatchedEvent event) {
            // When node is created, call the action.
            // Other event type would be handled by the action.
            if (event.getType() == Event.EventType.NodeCreated && nodeExists.compareAndSet(false, true)) {
                action.run();
            }
        }
    }), new FutureCallback<Stat>() {
        @Override
        public void onSuccess(Stat result) {
            if (result != null && nodeExists.compareAndSet(false, true)) {
                action.run();
            }
        }

        @Override
        public void onFailure(Throwable t) {
            LOG.error("Failed in exists call to {}. Shutting down service.", path, t);
            forceShutDown();
        }
    }, Threads.SAME_THREAD_EXECUTOR);
}

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From source file:com.continuuity.weave.internal.AbstractZKServiceController.java

License:Apache License

private void watchInstanceNode() {
    Futures.addCallback(zkClient.getData(getInstancePath(), new Watcher() {
        @Override/*from   w  ww.j  a v  a  2  s  . co m*/
        public void process(WatchedEvent event) {
            State state = state();
            if (state != State.NEW && state != State.STARTING && state != State.RUNNING) {
                // Ignore ZK node events when it is in stopping sequence.
                return;
            }
            switch (event.getType()) {
            case NodeDataChanged:
                watchInstanceNode();
                break;
            case NodeDeleted:
                // When the ephemeral node goes away, treat the remote service stopped.
                forceShutDown();
                break;
            default:
                LOG.info("Ignore ZK event for instance node: {}", event);
            }
        }
    }), instanceNodeDataCallback, Threads.SAME_THREAD_EXECUTOR);
}

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From source file:com.continuuity.weave.internal.AbstractZKServiceController.java

License:Apache License

private void watchStateNode() {
    Futures.addCallback(zkClient.getData(getZKPath("state"), new Watcher() {
        @Override/*from w ww .  j  a va  2 s.  co m*/
        public void process(WatchedEvent event) {
            State state = state();
            if (state != State.NEW && state != State.STARTING && state != State.RUNNING) {
                // Ignore ZK node events when it is in stopping sequence.
                return;
            }
            switch (event.getType()) {
            case NodeDataChanged:
                watchStateNode();
                break;
            default:
                LOG.info("Ignore ZK event for state node: {}", event);
            }
        }
    }), stateNodeDataCallback, Threads.SAME_THREAD_EXECUTOR);
}

---

From source file:com.continuuity.weave.internal.kafka.client.KafkaBrokerCache.java

License:Open Source License

private void getBrokers() {
    final String idsPath = BROKERS_PATH + "/ids";

    Futures.addCallback(zkClient.getChildren(idsPath, new Watcher() {
        @Override/*from   www .  ja va  2 s . c o m*/
        public void process(WatchedEvent event) {
            getBrokers();
        }
    }), new ExistsOnFailureFutureCallback<NodeChildren>(idsPath, invokeGetBrokers) {
        @Override
        public void onSuccess(NodeChildren result) {
            Set<String> children = ImmutableSet.copyOf(result.getChildren());
            for (String child : children) {
                getBrokenData(idsPath + "/" + child, child);
            }
            // Remove all removed brokers
            removeDiff(children, brokers);
        }
    });
}

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