| /** |
| * 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.framework.recipes.queue; |
| |
| import com.google.common.collect.ImmutableList; |
| import com.google.common.collect.Lists; |
| import org.apache.curator.framework.CuratorFramework; |
| import org.apache.curator.framework.WatcherRemoveCuratorFramework; |
| import org.apache.curator.framework.api.BackgroundCallback; |
| import org.apache.curator.framework.api.CuratorEvent; |
| import org.apache.curator.framework.api.CuratorWatcher; |
| import org.apache.zookeeper.KeeperException; |
| import org.apache.zookeeper.WatchedEvent; |
| import java.io.Closeable; |
| import java.io.IOException; |
| import java.util.List; |
| import java.util.concurrent.TimeUnit; |
| import java.util.concurrent.atomic.AtomicBoolean; |
| import java.util.concurrent.atomic.AtomicReference; |
| import org.apache.curator.utils.PathUtils; |
| |
| class ChildrenCache implements Closeable |
| { |
| private final WatcherRemoveCuratorFramework client; |
| private final String path; |
| private final AtomicReference<Data> children = new AtomicReference<Data>(new Data(Lists.<String>newArrayList(), 0)); |
| private final AtomicBoolean isClosed = new AtomicBoolean(false); |
| |
| private final CuratorWatcher watcher = new CuratorWatcher() |
| { |
| @Override |
| public void process(WatchedEvent event) throws Exception |
| { |
| if ( !isClosed.get() ) |
| { |
| sync(true); |
| } |
| } |
| }; |
| |
| private final BackgroundCallback callback = new BackgroundCallback() |
| { |
| @Override |
| public void processResult(CuratorFramework client, CuratorEvent event) throws Exception |
| { |
| if ( event.getResultCode() == KeeperException.Code.OK.intValue() ) |
| { |
| setNewChildren(event.getChildren()); |
| } |
| } |
| }; |
| |
| static class Data |
| { |
| final List<String> children; |
| final long version; |
| |
| private Data(List<String> children, long version) |
| { |
| this.children = ImmutableList.copyOf(children); |
| this.version = version; |
| } |
| } |
| |
| ChildrenCache(CuratorFramework client, String path) |
| { |
| this.client = client.newWatcherRemoveCuratorFramework(); |
| this.path = PathUtils.validatePath(path); |
| } |
| |
| void start() throws Exception |
| { |
| sync(true); |
| } |
| |
| @Override |
| public void close() throws IOException |
| { |
| client.removeWatchers(); |
| isClosed.set(true); |
| notifyFromCallback(); |
| } |
| |
| Data getData() |
| { |
| return children.get(); |
| } |
| |
| Data blockingNextGetData(long startVersion) throws InterruptedException |
| { |
| return blockingNextGetData(startVersion, 0, null); |
| } |
| |
| synchronized Data blockingNextGetData(long startVersion, long maxWait, TimeUnit unit) throws InterruptedException |
| { |
| long startMs = System.currentTimeMillis(); |
| boolean hasMaxWait = (unit != null); |
| long maxWaitMs = hasMaxWait ? unit.toMillis(maxWait) : -1; |
| while ( startVersion == children.get().version ) |
| { |
| if ( hasMaxWait ) |
| { |
| long elapsedMs = System.currentTimeMillis() - startMs; |
| long thisWaitMs = maxWaitMs - elapsedMs; |
| if ( thisWaitMs <= 0 ) |
| { |
| break; |
| } |
| wait(thisWaitMs); |
| } |
| else |
| { |
| wait(); |
| } |
| } |
| return children.get(); |
| } |
| |
| private synchronized void notifyFromCallback() |
| { |
| notifyAll(); |
| } |
| |
| private synchronized void sync(boolean watched) throws Exception |
| { |
| if ( watched ) |
| { |
| client.getChildren().usingWatcher(watcher).inBackground(callback).forPath(path); |
| } |
| else |
| { |
| client.getChildren().inBackground(callback).forPath(path); |
| } |
| } |
| |
| private synchronized void setNewChildren(List<String> newChildren) |
| { |
| if ( newChildren != null ) |
| { |
| Data currentData = children.get(); |
| |
| children.set(new Data(newChildren, currentData.version + 1)); |
| notifyFromCallback(); |
| } |
| } |
| } |