/*
 * Copyright (c) 2010-2012 Sonatype, Inc. All rights reserved.
 *
 * This program is licensed to you under the Apache License Version 2.0,
 * and you may not use this file except in compliance with the Apache License Version 2.0.
 * You may obtain a copy of the Apache License Version 2.0 at http://www.apache.org/licenses/LICENSE-2.0.
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the Apache License Version 2.0 is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the Apache License Version 2.0 for the specific language governing permissions and limitations there under.
 */
/*
 * 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.ning.http.client.listenable;

import com.ning.http.client.ListenableFuture;

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.
 *
 * @author Sven Mawson
 * @since 1
 */
public abstract class AbstractListenableFuture<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 ListenableFuture<V> addListener(Runnable listener, Executor exec) {
        executionList.add(listener, exec);
        return this;
    }

    /*
    * Override the done method to execute the execution list.
    */
    protected void done() {
        executionList.run();
    }
}