/*
* Copyright (C) 2007 Google Inc.
*
* Licensed 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 com.google.common.util.concurrent;
import java.util.concurrent.Executor;
/**
* <p>An abstract base implementation of the listener support provided by
* {@link ListenableFuture}. This class uses an {@link ExecutionList} to
* guarantee that all registered listeners will be executed. Listener/Executor
* pairs are stored in the execution list and executed in the order in which
* they were added, but because of thread scheduling issues there is no
* guarantee that the JVM will execute them in order. In addition, listeners
* added after the task is complete will be executed immediately, even if some
* previously added listeners have not yet been executed.
*
* <p>This class uses the {@link AbstractFuture} class to implement the
* {@code ListenableFuture} interface and simply delegates the
* {@link #addListener(Runnable, Executor)} and {@link #done()} methods to it.
*
* @author Sven Mawson
* @since 2009.09.15 <b>tentative</b>
*/
public abstract class AbstractListenableFuture<V>
extends AbstractFuture<V> implements ListenableFuture<V> {
// The execution list to hold our executors.
private final ExecutionList executionList = new ExecutionList();
/*
* Adds a listener/executor pair to execution list to execute when this task
* is completed.
*/
public void addListener(Runnable listener, Executor exec) {
executionList.add(listener, exec);
}
/*
* Override the done method to execute the execution list.
*/
@Override
protected void done() {
executionList.run();
}
}