core/src/main/java/flex/messaging/util/concurrent/DefaultThreadPoolExecutor.java

/*
 * 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 flex.messaging.util.concurrent;

import flex.messaging.log.Log;
import flex.messaging.log.LogCategories;

import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.RejectedExecutionHandler;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.RejectedExecutionException;

/**
 * Implements {@link Executor} and extends the <code>ThreadPoolExecutor</code> provided by the
 * Java 1.4.x-friendly backport of the <code>java.util.concurrent</code> API.
 */
public class DefaultThreadPoolExecutor extends ThreadPoolExecutor implements Executor {
    //--------------------------------------------------------------------------
    //
    // Constructors
    //
    //--------------------------------------------------------------------------

    /**
     * Constructs a <code>DefaultThreadPoolExecutor</code> with configuration that
     * matches the return from {@link java.util.concurrent.Executors#newCachedThreadPool()}.
     */
    public DefaultThreadPoolExecutor() {
        super(0, Integer.MAX_VALUE, 60L, TimeUnit.SECONDS, new SynchronousQueue());
    }

    /**
     * @see java.util.concurrent.ThreadPoolExecutor#ThreadPoolExecutor(int, int, long, java.util.concurrent.TimeUnit, java.util.concurrent.BlockingQueue)
     */
    public DefaultThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue workQueue) {
        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue);
    }

    /**
     * @see java.util.concurrent.ThreadPoolExecutor#ThreadPoolExecutor(int, int, long, java.util.concurrent.TimeUnit, java.util.concurrent.BlockingQueue, java.util.concurrent.RejectedExecutionHandler)
     */
    public DefaultThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue workQueue, RejectedExecutionHandler handler) {
        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, handler);
    }

    /**
     * @see java.util.concurrent.ThreadPoolExecutor#ThreadPoolExecutor(int, int, long, java.util.concurrent.TimeUnit, java.util.concurrent.BlockingQueue, java.util.concurrent.ThreadFactory)
     */
    public DefaultThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue workQueue, ThreadFactory threadFactory) {
        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory);
    }

    /**
     * @see java.util.concurrent.ThreadPoolExecutor#ThreadPoolExecutor(int, int, long, java.util.concurrent.TimeUnit, java.util.concurrent.BlockingQueue, java.util.concurrent.ThreadFactory, java.util.concurrent.RejectedExecutionHandler)
     */
    public DefaultThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue workQueue, ThreadFactory threadFactory, RejectedExecutionHandler handler) {
        super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory, handler);
    }

    //--------------------------------------------------------------------------
    //
    // Variables
    //
    //--------------------------------------------------------------------------

    /**
     * Instance-level lock.
     */
    private final Object lock = new Object();

    //--------------------------------------------------------------------------
    //
    // Properties
    //
    //--------------------------------------------------------------------------

    //----------------------------------
    //  failedExecutionHandler
    //----------------------------------

    private FailedExecutionHandler handler;

    /**
     * @see Executor#getFailedExecutionHandler()
     */
    public FailedExecutionHandler getFailedExecutionHandler() {
        synchronized (lock) {
            return handler;
        }
    }

    /**
     * @see Executor#setFailedExecutionHandler(FailedExecutionHandler)
     */
    public void setFailedExecutionHandler(FailedExecutionHandler value) {
        synchronized (lock) {
            handler = value;
        }
    }

    //--------------------------------------------------------------------------
    //
    // Overridden Public Methods
    //
    //--------------------------------------------------------------------------

    /**
     * This implementation relies on the default <code>RejectedExecutionHandler</code>, {@link java.util.concurrent.ThreadPoolExecutor.AbortPolicy}, which
     * throws a <code>RejectedExecutionException</code> if the command cannot be queued for execution.
     */
    public void execute(Runnable command) {
        try {
            super.execute(command);
        } catch (RejectedExecutionException e) {
            FailedExecutionHandler handler = getFailedExecutionHandler();
            if (handler != null) {
                handler.failedExecution(command, this, e);
            } else if (Log.isError()) {
                Log.getLogger(LogCategories.EXECUTOR).error("DefaultThreadPoolExecutor hit a RejectedExecutionException but no FailedExecutionHandler is registered to handle the error.", e);
            }
        }
    }
}