001    /**
002     * Copyright (c) 2000-2013 Liferay, Inc. All rights reserved.
003     *
004     * This library is free software; you can redistribute it and/or modify it under
005     * the terms of the GNU Lesser General Public License as published by the Free
006     * Software Foundation; either version 2.1 of the License, or (at your option)
007     * any later version.
008     *
009     * This library is distributed in the hope that it will be useful, but WITHOUT
010     * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
011     * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
012     * details.
013     */
014    
015    package com.liferay.portal.kernel.concurrent;
016    
017    /**
018     * Implements the same behavior as {@link
019     * java.util.concurrent.ThreadPoolExecutor.DiscardOldestPolicy}.
020     *
021     * @author Shuyang Zhou
022     * @see    java.util.concurrent.ThreadPoolExecutor.DiscardOldestPolicy
023     */
024    public class DiscardOldestPolicy implements RejectedExecutionHandler {
025    
026            /**
027             * @see java.util.concurrent.ThreadPoolExecutor.DiscardOldestPolicy#rejectedExecution(
028             *      Runnable, java.util.concurrent.ThreadPoolExecutor)
029             */
030            @Override
031            public void rejectedExecution(
032                    Runnable runnable, ThreadPoolExecutor threadPoolExecutor) {
033    
034                    if (threadPoolExecutor.isShutdown()) {
035                            return;
036                    }
037    
038                    TaskQueue<Runnable> taskQueue = threadPoolExecutor.getTaskQueue();
039    
040                    taskQueue.poll();
041    
042                    threadPoolExecutor.execute(runnable);
043            }
044    
045    }