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 */ 017package org.apache.camel.util.concurrent; 018 019import java.util.concurrent.BlockingQueue; 020import java.util.concurrent.Callable; 021import java.util.concurrent.RejectedExecutionHandler; 022import java.util.concurrent.RunnableFuture; 023import java.util.concurrent.ThreadFactory; 024import java.util.concurrent.ThreadPoolExecutor; 025import java.util.concurrent.TimeUnit; 026 027import org.apache.camel.Rejectable; 028 029/** 030 * Thread pool executor that creates {@link RejectableFutureTask} instead of 031 * {@link java.util.concurrent.FutureTask} when registering new tasks for execution. 032 * <p/> 033 * Instances of {@link RejectableFutureTask} are required to handle {@link org.apache.camel.ThreadPoolRejectedPolicy#Discard} 034 * and {@link org.apache.camel.ThreadPoolRejectedPolicy#DiscardOldest} policies correctly, e.g. notify 035 * {@link Callable} and {@link Runnable} tasks when they are rejected. 036 * To be notified of rejection tasks have to implement {@link org.apache.camel.Rejectable} interface: <br/> 037 * <code><pre> 038 * public class RejectableTask implements Runnable, Rejectable { 039 * @Override 040 * public void run() { 041 * // execute task 042 * } 043 * @Override 044 * public void reject() { 045 * // do something useful on rejection 046 * } 047 * } 048 * </pre></code> 049 * <p/> 050 * If the task does not implement {@link org.apache.camel.Rejectable} interface the behavior is exactly the same as with 051 * ordinary {@link ThreadPoolExecutor}. 052 * 053 * @see RejectableFutureTask 054 * @see org.apache.camel.Rejectable 055 * @see RejectableScheduledThreadPoolExecutor 056 */ 057public class RejectableThreadPoolExecutor extends ThreadPoolExecutor { 058 059 public RejectableThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, 060 BlockingQueue<Runnable> workQueue) { 061 super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue); 062 } 063 064 public RejectableThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, 065 BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory) { 066 super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory); 067 } 068 069 public RejectableThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, 070 BlockingQueue<Runnable> workQueue, RejectedExecutionHandler handler) { 071 super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, handler); 072 } 073 074 public RejectableThreadPoolExecutor(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, 075 BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory, RejectedExecutionHandler handler) { 076 super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, threadFactory, handler); 077 } 078 079 @Override 080 protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) { 081 if (runnable instanceof Rejectable) { 082 return new RejectableFutureTask<T>(runnable, value); 083 } else { 084 return super.newTaskFor(runnable, value); 085 } 086 } 087 088 @Override 089 protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) { 090 if (callable instanceof Rejectable) { 091 return new RejectableFutureTask<T>(callable); 092 } else { 093 return super.newTaskFor(callable); 094 } 095 } 096 097 @Override 098 public String toString() { 099 // the thread factory often have more precise details what the thread pool is used for 100 if (getThreadFactory() instanceof CamelThreadFactory) { 101 String name = ((CamelThreadFactory) getThreadFactory()).getName(); 102 return super.toString() + "[" + name + "]"; 103 } else { 104 return super.toString(); 105 } 106 } 107 108}