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:org.apache.solr.schema.ZkIndexSchemaReader.java

License:Apache License

public void createSchemaWatcher() {
    log.info("Creating ZooKeeper watch for the managed schema at " + managedSchemaPath + " ...");

    try {//from ww  w  . j  av a  2 s .com
        zkClient.exists(managedSchemaPath, new Watcher() {
            @Override
            public void process(WatchedEvent event) {
                // session events are not change events, and do not remove the watcher
                if (Event.EventType.None.equals(event.getType())) {
                    return;
                }
                log.info("A schema change: {}, has occurred - updating schema from ZooKeeper ...", event);
                try {
                    updateSchema(this);
                } catch (KeeperException e) {
                    if (e.code() == KeeperException.Code.SESSIONEXPIRED
                            || e.code() == KeeperException.Code.CONNECTIONLOSS) {
                        log.warn("ZooKeeper watch triggered, but Solr cannot talk to ZK");
                        return;
                    }
                    log.error("", e);
                    throw new ZooKeeperException(ErrorCode.SERVER_ERROR, "", e);
                } catch (InterruptedException e) {
                    // Restore the interrupted status
                    Thread.currentThread().interrupt();
                    log.warn("", e);
                }
            }
        }, true);
    } catch (KeeperException e) {
        final String msg = "Error creating ZooKeeper watch for the managed schema";
        log.error(msg, e);
        throw new ZooKeeperException(ErrorCode.SERVER_ERROR, msg, e);
    } catch (InterruptedException e) {
        // Restore the interrupted status
        Thread.currentThread().interrupt();
        log.warn("", e);
    }
}

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From source file:org.apache.solr.security.hadoop.TestZkAclsWithHadoopAuth.java

License:Apache License

@Test
public void testZkAcls() throws Exception {
    ZooKeeper keeper = null;//  ww w.j a  v a  2 s .  c om
    try {
        keeper = new ZooKeeper(cluster.getZkServer().getZkAddress(), (int) TimeUnit.MINUTES.toMillis(1),
                new Watcher() {
                    @Override
                    public void process(WatchedEvent arg0) {
                        // Do nothing
                    }
                });

        keeper.addAuthInfo("digest", ("solr:" + SOLR_PASSWD).getBytes(StandardCharsets.UTF_8));

        // Test well known paths.
        checkNonSecurityACLs(keeper, "/solr.xml");
        checkSecurityACLs(keeper, "/security/token");
        checkSecurityACLs(keeper, "/security");

        // Now test all ZK tree.
        String zkHost = cluster.getSolrClient().getZkHost();
        String zkChroot = zkHost.contains("/") ? zkHost.substring(zkHost.indexOf("/")) : null;
        walkZkTree(keeper, zkChroot, "/");

    } finally {
        if (keeper != null) {
            keeper.close();
        }
    }
}

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From source file:org.apache.tephra.distributed.ThriftTransactionServerTest.java

License:Apache License

private void expireZkSession(ZKClientService zkClientService) throws Exception {
    ZooKeeper zooKeeper = zkClientService.getZooKeeperSupplier().get();
    final SettableFuture<?> connectFuture = SettableFuture.create();
    Watcher watcher = new Watcher() {
        @Override/*from  www  .j a va2s .  co  m*/
        public void process(WatchedEvent event) {
            if (event.getState() == Event.KeeperState.SyncConnected) {
                connectFuture.set(null);
            }
        }
    };

    // Create another Zookeeper session with the same sessionId so that the original one expires.
    ZooKeeper dupZookeeper = new ZooKeeper(zkClientService.getConnectString(), zooKeeper.getSessionTimeout(),
            watcher, zooKeeper.getSessionId(), zooKeeper.getSessionPasswd());
    connectFuture.get(30, TimeUnit.SECONDS);
    Assert.assertEquals("Failed to re-create current session", dupZookeeper.getState(),
            ZooKeeper.States.CONNECTED);
    dupZookeeper.close();
}

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From source file:org.apache.twill.discovery.ZKDiscoveryService.java

License:Apache License

private Watcher createConnectionWatcher() {
    return new Watcher() {
        // Watcher is invoked from single event thread, hence safe to use normal mutable variable.
        private boolean expired;

        @Override/*  w  ww  . j a  v a2  s .  c o  m*/
        public void process(WatchedEvent event) {
            if (event.getState() == Event.KeeperState.Expired) {
                LOG.warn("ZK Session expired: {}", zkClient.getConnectString());
                expired = true;
            } else if (event.getState() == Event.KeeperState.SyncConnected && expired) {
                LOG.info("Reconnected after expiration: {}", zkClient.getConnectString());
                expired = false;

                // Re-register all services
                lock.lock();
                try {
                    for (final Map.Entry<Discoverable, DiscoveryCancellable> entry : discoverables.entries()) {
                        LOG.info("Re-registering service: {}", entry.getKey());

                        // Must be non-blocking in here.
                        Futures.addCallback(doRegister(entry.getKey()), new FutureCallback<String>() {
                            @Override
                            public void onSuccess(String result) {
                                // Updates the cancellable to the newly created sequential node.
                                entry.getValue().setPath(result);
                                LOG.debug("Service re-registered: {} {}", entry.getKey(), result);
                            }

                            @Override
                            public void onFailure(Throwable t) {
                                // When failed to create the node, there would be no retry and simply make the cancellable do nothing.
                                entry.getValue().setPath(null);
                                LOG.error("Failed to re-register service: {}", entry.getKey(), t);
                            }
                        }, Threads.SAME_THREAD_EXECUTOR);
                    }
                } finally {
                    lock.unlock();
                }
            }
        }
    };
}

---

From source file:org.apache.twill.internal.AbstractTwillService.java

License:Apache License

@Override
protected final void startUp() throws Exception {
    // Single thread executor that will discard task silently if it is already terminated, which only
    // happens when this service is shutting down.
    messageCallbackExecutor = new ThreadPoolExecutor(1, 1, 0L, TimeUnit.MILLISECONDS,
            new LinkedBlockingQueue<Runnable>(), Threads.createDaemonThreadFactory("message-callback"),
            new ThreadPoolExecutor.DiscardPolicy());

    // Watch for session expiration, recreate the live node if reconnected after expiration.
    zkClient.addConnectionWatcher(new Watcher() {
        private boolean expired = false;

        @Override//from  ww w.j a v  a 2 s.  com
        public void process(WatchedEvent event) {
            if (event.getState() == Event.KeeperState.Expired) {
                LOG.warn("ZK Session expired for service {} with runId {}.", getServiceName(), runId.getId());
                expired = true;
            } else if (event.getState() == Event.KeeperState.SyncConnected && expired) {
                LOG.info("Reconnected after expiration for service {} with runId {}", getServiceName(),
                        runId.getId());
                expired = false;
                logIfFailed(createLiveNode());
            }
        }
    });

    // Create the live node, if succeeded, start the service, otherwise fail out.
    createLiveNode().get();

    // Create node for messaging
    ZKOperations.ignoreError(zkClient.create(getZKPath("messages"), null, CreateMode.PERSISTENT),
            KeeperException.NodeExistsException.class, null).get();

    doStart();

    // Starts watching for messages
    watchMessages();
}

---

From source file:org.apache.twill.internal.AbstractTwillService.java

License:Apache License

/**
 * Watches for messages that are sent through ZK messages node.
 *//*www  .  j a  va  2  s.  c o  m*/
private void watchMessages() {
    final String messagesPath = getZKPath("messages");
    Futures.addCallback(zkClient.getChildren(messagesPath, new Watcher() {
        @Override
        public void process(WatchedEvent event) {
            if (event.getType() == Event.EventType.NodeChildrenChanged && isRunning()) {
                watchMessages();
            }
        }
    }), new FutureCallback<NodeChildren>() {
        @Override
        public void onSuccess(NodeChildren result) {
            // Sort by the name, which is the messageId. Assumption is that message ids is ordered by time.
            List<String> messages = Lists.newArrayList(result.getChildren());
            Collections.sort(messages);
            for (String messageId : messages) {
                processMessage(messagesPath + "/" + messageId, messageId);
            }
        }

        @Override
        public void onFailure(Throwable t) {
            // TODO: what could be done besides just logging?
            LOG.error("Failed to watch messages.", t);
        }
    }, Threads.SAME_THREAD_EXECUTOR);
}

---

From source file:org.apache.twill.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  va 2  s.co m*/
        public void process(WatchedEvent event) {
            if (!shouldProcessZKEvent()) {
                return;
            }
            // 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);
}

---

From source file:org.apache.twill.internal.AbstractZKServiceController.java

License:Apache License

protected final void watchInstanceNode() {
    if (!shouldProcessZKEvent()) {
        return;//from   w  w w. j a  v  a 2  s . co  m
    }
    Futures.addCallback(zkClient.getData(getInstancePath(), new Watcher() {
        @Override
        public void process(WatchedEvent event) {
            if (!shouldProcessZKEvent()) {
                return;
            }
            switch (event.getType()) {
            case NodeDataChanged:
                watchInstanceNode();
                break;
            case NodeDeleted:
                instanceNodeFailed(KeeperException.create(KeeperException.Code.NONODE, getInstancePath()));
                break;
            default:
                LOG.info("Ignore ZK event for instance node: {}", event);
            }
        }
    }), instanceNodeDataCallback, Threads.SAME_THREAD_EXECUTOR);
}

---

From source file:org.apache.twill.internal.kafka.client.ZKBrokerService.java

License:Apache License

@Override
public synchronized Iterable<BrokerInfo> getBrokers() {
    Preconditions.checkState(isRunning(), "BrokerService is not running.");

    if (brokerList != null) {
        return brokerList.get();
    }/*from  w  w w .  jav  a 2 s  . c o  m*/

    final SettableFuture<?> readerFuture = SettableFuture.create();
    final AtomicReference<Iterable<BrokerInfo>> brokers = new AtomicReference<Iterable<BrokerInfo>>(
            ImmutableList.<BrokerInfo>of());

    actOnExists(BROKER_IDS_PATH, new Runnable() {
        @Override
        public void run() {
            // Callback for fetching children list. This callback should be executed in the executorService.
            final FutureCallback<NodeChildren> childrenCallback = new FutureCallback<NodeChildren>() {
                @Override
                public void onSuccess(NodeChildren result) {
                    try {
                        // For each children node, get the BrokerInfo from the brokerInfo cache.
                        brokers.set(ImmutableList.copyOf(Iterables.transform(brokerInfos
                                .getAll(Iterables.transform(result.getChildren(), BROKER_ID_TRANSFORMER))
                                .values(), Suppliers.<BrokerInfo>supplierFunction())));
                        readerFuture.set(null);

                        for (ListenerExecutor listener : listeners) {
                            listener.changed(ZKBrokerService.this);
                        }
                    } catch (ExecutionException e) {
                        readerFuture.setException(e.getCause());
                    }
                }

                @Override
                public void onFailure(Throwable t) {
                    readerFuture.setException(t);
                }
            };

            // Fetch list of broker ids
            Futures.addCallback(zkClient.getChildren(BROKER_IDS_PATH, new Watcher() {
                @Override
                public void process(WatchedEvent event) {
                    if (!isRunning()) {
                        return;
                    }
                    if (event.getType() == Event.EventType.NodeChildrenChanged) {
                        Futures.addCallback(zkClient.getChildren(BROKER_IDS_PATH, this), childrenCallback,
                                executorService);
                    }
                }
            }), childrenCallback, executorService);
        }
    }, readerFuture, FAILURE_RETRY_SECONDS, TimeUnit.SECONDS);

    brokerList = createSupplier(brokers);
    try {
        readerFuture.get();
    } catch (Exception e) {
        throw Throwables.propagate(e);
    }
    return brokerList.get();
}

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From source file:org.apache.twill.internal.kafka.client.ZKBrokerService.java

License:Apache License

/**
 * Creates a cache loader for the given path to supply data with the data node.
 *//*from  www.j a v  a2 s  .c  om*/
private <K extends KeyPath, T> CacheLoader<K, Supplier<T>> createCacheLoader(
        final CacheInvalidater<K> invalidater, final Class<T> resultType) {
    return new CacheLoader<K, Supplier<T>>() {

        @Override
        public Supplier<T> load(final K key) throws Exception {
            // A future to tell if the result is ready, even it is failure.
            final SettableFuture<T> readyFuture = SettableFuture.create();
            final AtomicReference<T> resultValue = new AtomicReference<T>();

            // Fetch for node data when it exists.
            final String path = key.getPath();
            actOnExists(path, new Runnable() {
                @Override
                public void run() {
                    // Callback for getData call
                    final FutureCallback<NodeData> dataCallback = new FutureCallback<NodeData>() {
                        @Override
                        public void onSuccess(NodeData result) {
                            // Update with latest data
                            T value = decodeNodeData(result, resultType);
                            resultValue.set(value);
                            readyFuture.set(value);
                        }

                        @Override
                        public void onFailure(Throwable t) {
                            LOG.error("Failed to fetch node data on {}", path, t);
                            if (t instanceof KeeperException.NoNodeException) {
                                resultValue.set(null);
                                readyFuture.set(null);
                                return;
                            }

                            // On error, simply invalidate the key so that it'll be fetched next time.
                            invalidater.invalidate(key);
                            readyFuture.setException(t);
                        }
                    };

                    // Fetch node data
                    Futures.addCallback(zkClient.getData(path, new Watcher() {
                        @Override
                        public void process(WatchedEvent event) {
                            if (!isRunning()) {
                                return;
                            }
                            if (event.getType() == Event.EventType.NodeDataChanged) {
                                // If node data changed, fetch it again.
                                Futures.addCallback(zkClient.getData(path, this), dataCallback,
                                        executorService);
                            } else if (event.getType() == Event.EventType.NodeDeleted) {
                                // If node removed, invalidate the cached value.
                                brokerInfos.invalidate(key);
                            }
                        }
                    }), dataCallback, executorService);
                }
            }, readyFuture, FAILURE_RETRY_SECONDS, TimeUnit.SECONDS);

            readyFuture.get();
            return createSupplier(resultValue);
        }
    };
}

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