001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.camel.util.concurrent;
018    
019    import java.util.concurrent.BlockingQueue;
020    import java.util.concurrent.Callable;
021    import java.util.concurrent.RejectedExecutionHandler;
022    import java.util.concurrent.RunnableFuture;
023    import java.util.concurrent.ThreadFactory;
024    import java.util.concurrent.ThreadPoolExecutor;
025    import java.util.concurrent.TimeUnit;
026    
027    /**
028     * Thread pool executor that creates {@link RejectableFutureTask} instead of
029     * {@link java.util.concurrent.FutureTask} when registering new tasks for execution.
030     * <p/>
031     * Instances of {@link RejectableFutureTask} are required to handle {@link org.apache.camel.ThreadPoolRejectedPolicy#Discard}
032     * and {@link org.apache.camel.ThreadPoolRejectedPolicy#DiscardOldest} policies correctly, e.g. notify
033     * {@link Callable} and {@link Runnable} tasks when they are rejected.
034     * To be notified of rejection tasks have to implement {@link org.apache.camel.Rejectable} interface: <br/>
035     * <code><pre>
036     * public class RejectableTask implements Runnable, Rejectable {
037     *     &#064;Override
038     *     public void run() {
039     *         // execute task
040     *     }
041     *     &#064;Override
042     *     public void reject() {
043     *         // do something useful on rejection
044     *     }
045     * }
046     * </pre></code>
047     * <p/>
048     * If the task does not implement {@link org.apache.camel.Rejectable} interface the behavior is exactly the same as with
049     * ordinary {@link ThreadPoolExecutor}.
050     *
051     * @see RejectableFutureTask
052     * @see org.apache.camel.Rejectable
053     * @see RejectableScheduledThreadPoolExecutor
054     */
055    public class RejectableThreadPoolExecutor extends ThreadPoolExecutor {
056    
057        public RejectableThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit,
058                                            BlockingQueue<Runnable> workQueue) {
059            super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue);
060        }
061    
062        public RejectableThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit,
063                                            BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory) {
064            super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory);
065        }
066    
067        public RejectableThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit,
068                                            BlockingQueue<Runnable> workQueue, RejectedExecutionHandler handler) {
069            super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, handler);
070        }
071    
072        public RejectableThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit,
073                                            BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory, RejectedExecutionHandler handler) {
074            super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory, handler);
075        }
076    
077        @Override
078        protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) {
079            return new RejectableFutureTask<T>(runnable, value);
080        }
081    
082        @Override
083        protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) {
084            return new RejectableFutureTask<T>(callable);
085        }
086    
087    }