| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| package org.apache.curator.v2.recipes.watch; |
| |
| import com.google.common.base.Preconditions; |
| import org.apache.curator.framework.CuratorFramework; |
| import org.apache.curator.framework.api.BackgroundCallback; |
| import org.apache.curator.framework.listen.Listenable; |
| import org.apache.curator.framework.listen.StandardListenerManager; |
| import org.apache.curator.framework.state.ConnectionStateListener; |
| import org.apache.curator.utils.ThreadUtils; |
| import org.apache.curator.v2.CuratorFrameworkV2; |
| import org.apache.zookeeper.AddWatchMode; |
| import org.apache.zookeeper.KeeperException; |
| import org.apache.zookeeper.Watcher; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| import java.io.Closeable; |
| import java.util.Objects; |
| import java.util.concurrent.atomic.AtomicReference; |
| |
| /** |
| * A managed persistent watcher. The watch will be managed such that it stays set through |
| * connection lapses, etc. |
| */ |
| public class PersistentWatcher implements Closeable |
| { |
| private final Logger log = LoggerFactory.getLogger(getClass()); |
| private final AtomicReference<State> state = new AtomicReference<>(State.LATENT); |
| private final StandardListenerManager<Watcher> listeners = StandardListenerManager.standard(); |
| private final StandardListenerManager<Runnable> resetListeners = StandardListenerManager.standard(); |
| private final ConnectionStateListener connectionStateListener = (client, newState) -> { |
| if ( newState.isConnected() ) |
| { |
| reset(); |
| } |
| }; |
| private final Watcher watcher = event -> listeners.forEach(w -> w.process(event)); |
| private final CuratorFrameworkV2 client; |
| private final String basePath; |
| private final boolean recursive; |
| |
| private enum State |
| { |
| LATENT, |
| STARTED, |
| CLOSED |
| } |
| |
| /** |
| * @param client client |
| * @param basePath path to set the watch on |
| * @param recursive ZooKeeper persistent watches can optionally be recursive |
| */ |
| public PersistentWatcher(CuratorFramework client, String basePath, boolean recursive) |
| { |
| this(CuratorFrameworkV2.wrap(client), basePath, recursive); |
| } |
| |
| /** |
| * @param client client |
| * @param basePath path to set the watch on |
| * @param recursive ZooKeeper persistent watches can optionally be recursive |
| */ |
| public PersistentWatcher(CuratorFrameworkV2 client, String basePath, boolean recursive) |
| { |
| this.client = Objects.requireNonNull(client, "client cannot be null"); |
| this.basePath = Objects.requireNonNull(basePath, "basePath cannot be null"); |
| this.recursive = recursive; |
| } |
| |
| /** |
| * Start watching |
| */ |
| public void start() |
| { |
| Preconditions.checkState(state.compareAndSet(State.LATENT, State.STARTED), "Already started"); |
| client.getConnectionStateListenable().addListener(connectionStateListener); |
| reset(); |
| } |
| |
| /** |
| * Remove the watcher |
| */ |
| @Override |
| public void close() |
| { |
| if ( state.compareAndSet(State.STARTED, State.CLOSED) ) |
| { |
| listeners.clear(); |
| client.getConnectionStateListenable().removeListener(connectionStateListener); |
| try |
| { |
| client.watches().remove(watcher).guaranteed().inBackground().forPath(basePath); |
| } |
| catch ( Exception e ) |
| { |
| ThreadUtils.checkInterrupted(e); |
| log.debug(String.format("Could not remove watcher for path: %s", basePath), e); |
| } |
| } |
| } |
| |
| /** |
| * Container for setting listeners |
| * |
| * @return listener container |
| */ |
| public Listenable<Watcher> getListenable() |
| { |
| return listeners; |
| } |
| |
| /** |
| * Listeners are called when the persistent watcher has been successfully registered |
| * or re-registered after a connection disruption |
| * |
| * @return listener container |
| */ |
| public StandardListenerManager<Runnable> getResetListenable() |
| { |
| return resetListeners; |
| } |
| |
| private void reset() |
| { |
| try |
| { |
| BackgroundCallback callback = (__, event) -> { |
| if ( event.getResultCode() != KeeperException.Code.OK.intValue() ) |
| { |
| reset(); |
| } |
| else |
| { |
| resetListeners.forEach(Runnable::run); |
| } |
| }; |
| client.watches().add().withMode(recursive ? AddWatchMode.PERSISTENT_RECURSIVE : AddWatchMode.PERSISTENT).inBackground(callback).usingWatcher(watcher).forPath(basePath); |
| } |
| catch ( Exception e ) |
| { |
| log.error("Could not reset persistent watch at path: " + basePath, e); |
| } |
| } |
| } |