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.impl;
018
019import java.util.concurrent.BlockingQueue;
020import java.util.concurrent.ExecutorService;
021import java.util.concurrent.Executors;
022import java.util.concurrent.LinkedBlockingQueue;
023import java.util.concurrent.RejectedExecutionHandler;
024import java.util.concurrent.ScheduledExecutorService;
025import java.util.concurrent.ScheduledThreadPoolExecutor;
026import java.util.concurrent.SynchronousQueue;
027import java.util.concurrent.ThreadFactory;
028import java.util.concurrent.ThreadPoolExecutor;
029import java.util.concurrent.TimeUnit;
030
031import org.apache.camel.spi.ThreadPoolFactory;
032import org.apache.camel.spi.ThreadPoolProfile;
033import org.apache.camel.util.concurrent.RejectableScheduledThreadPoolExecutor;
034import org.apache.camel.util.concurrent.RejectableThreadPoolExecutor;
035import org.apache.camel.util.concurrent.SizedScheduledExecutorService;
036
037/**
038 * Factory for thread pools that uses the JDK {@link Executors} for creating the thread pools.
039 */
040public class DefaultThreadPoolFactory implements ThreadPoolFactory {
041
042    public ExecutorService newCachedThreadPool(ThreadFactory threadFactory) {
043        return Executors.newCachedThreadPool(threadFactory);
044    }
045    
046    @Override
047    public ExecutorService newThreadPool(ThreadPoolProfile profile, ThreadFactory factory) {
048        return newThreadPool(profile.getPoolSize(), 
049                             profile.getMaxPoolSize(), 
050                             profile.getKeepAliveTime(),
051                             profile.getTimeUnit(),
052                             profile.getMaxQueueSize(), 
053                             profile.getRejectedExecutionHandler(),
054                             factory);
055    }
056
057    public ExecutorService newThreadPool(int corePoolSize, int maxPoolSize, long keepAliveTime, TimeUnit timeUnit,
058                                         int maxQueueSize, RejectedExecutionHandler rejectedExecutionHandler,
059                                         ThreadFactory threadFactory) throws IllegalArgumentException {
060
061        // the core pool size must be 0 or higher
062        if (corePoolSize < 0) {
063            throw new IllegalArgumentException("CorePoolSize must be >= 0, was " + corePoolSize);
064        }
065
066        // validate max >= core
067        if (maxPoolSize < corePoolSize) {
068            throw new IllegalArgumentException("MaxPoolSize must be >= corePoolSize, was " + maxPoolSize + " >= " + corePoolSize);
069        }
070
071        BlockingQueue<Runnable> workQueue;
072        if (corePoolSize == 0 && maxQueueSize <= 0) {
073            // use a synchronous queue for direct-handover (no tasks stored on the queue)
074            workQueue = new SynchronousQueue<Runnable>();
075            // and force 1 as pool size to be able to create the thread pool by the JDK
076            corePoolSize = 1;
077            maxPoolSize = 1;
078        } else if (maxQueueSize <= 0) {
079            // use a synchronous queue for direct-handover (no tasks stored on the queue)
080            workQueue = new SynchronousQueue<Runnable>();
081        } else {
082            // bounded task queue to store tasks on the queue
083            workQueue = new LinkedBlockingQueue<Runnable>(maxQueueSize);
084        }
085
086        ThreadPoolExecutor answer = new RejectableThreadPoolExecutor(corePoolSize, maxPoolSize, keepAliveTime, timeUnit, workQueue);
087        answer.setThreadFactory(threadFactory);
088        if (rejectedExecutionHandler == null) {
089            rejectedExecutionHandler = new ThreadPoolExecutor.CallerRunsPolicy();
090        }
091        answer.setRejectedExecutionHandler(rejectedExecutionHandler);
092        return answer;
093    }
094    
095    @Override
096    public ScheduledExecutorService newScheduledThreadPool(ThreadPoolProfile profile, ThreadFactory threadFactory) {
097        RejectedExecutionHandler rejectedExecutionHandler = profile.getRejectedExecutionHandler();
098        if (rejectedExecutionHandler == null) {
099            rejectedExecutionHandler = new ThreadPoolExecutor.CallerRunsPolicy();
100        }
101
102        ScheduledThreadPoolExecutor answer = new RejectableScheduledThreadPoolExecutor(profile.getPoolSize(), threadFactory, rejectedExecutionHandler);
103        // TODO: when JDK7 we should setRemoveOnCancelPolicy(true)
104
105        // need to wrap the thread pool in a sized to guard against the problem that the
106        // JDK created thread pool has an unbounded queue (see class javadoc), which mean
107        // we could potentially keep adding tasks, and run out of memory.
108        if (profile.getMaxPoolSize() > 0) {
109            return new SizedScheduledExecutorService(answer, profile.getMaxQueueSize());
110        } else {
111            return answer;
112        }
113    }
114
115}