| /* |
| * 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.jackrabbit.oak.commons.concurrent; |
| |
| import java.util.concurrent.Callable; |
| import java.util.concurrent.Future; |
| import java.util.concurrent.FutureTask; |
| import java.util.concurrent.atomic.AtomicBoolean; |
| |
| /** |
| * A {@link Future} that accepts completion listener. The listener is invoked |
| * once the future's computation is {@linkplain Future#isDone() complete}. |
| * If the computation has already completed when the listener is added, the |
| * listener will execute immediately. |
| * |
| * <p>Listener is invoked synchronously on the same thread which is used to |
| * executed the Future</p> |
| */ |
| public class NotifyingFutureTask extends FutureTask<Void> { |
| private final AtomicBoolean completed = new AtomicBoolean(false); |
| |
| private volatile Runnable onComplete; |
| |
| public NotifyingFutureTask(Callable<Void> callable) { |
| super(callable); |
| } |
| |
| public NotifyingFutureTask(Runnable task) { |
| super(task, null); |
| } |
| |
| /** |
| * Set the on complete handler. The handler will run exactly once after |
| * the task terminated. If the task has already terminated at the time of |
| * this method call the handler will execute immediately. |
| * <p> |
| * Note: there is no guarantee to which handler will run when the method |
| * is called multiple times with different arguments. |
| * </p> |
| * @param onComplete listener to invoke upon completion |
| */ |
| public void onComplete(Runnable onComplete) { |
| this.onComplete = onComplete; |
| if (isDone()) { |
| run(onComplete); |
| } |
| } |
| |
| @Override |
| protected void done() { |
| run(onComplete); |
| } |
| |
| private void run(Runnable onComplete) { |
| if (onComplete != null && completed.compareAndSet(false, true)) { |
| onComplete.run(); |
| } |
| } |
| |
| private static final Runnable NOP = new Runnable() { |
| @Override |
| public void run() { |
| } |
| }; |
| |
| public static NotifyingFutureTask completed() { |
| NotifyingFutureTask f = new NotifyingFutureTask(NOP); |
| f.run(); |
| return f; |
| } |
| } |