Tomcat example source code file (RxTaskPool.java)

This example Tomcat source code file (RxTaskPool.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Tomcat tags/keywords

abstractrxtask, abstractrxtask, exception, iterator, linkedlist, list, object, object, rxtaskpool, rxtaskpool, taskcreator, taskcreator, threading, threads, util

The Tomcat RxTaskPool.java source code

/*
 * 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 org.apache.catalina.tribes.transport;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.ThreadFactory;

/**
 * @author not attributable
 * @version 1.0
 */

public class RxTaskPool
{
    /**
     * A very simple thread pool class.  The pool size is set at
     * construction time and remains fixed.  Threads are cycled
     * through a FIFO idle queue.
     */

    List idle = new LinkedList();
    List used = new LinkedList();
    
    Object mutex = new Object();
    boolean running = true;
    
    private static int counter = 1;
    private int maxTasks;
    private int minTasks;
    
    private TaskCreator creator = null;

    private static synchronized int inc() {
        return counter++;
    }

    
    public RxTaskPool (int maxTasks, int minTasks, TaskCreator creator) throws Exception {
        // fill up the pool with worker threads
        this.maxTasks = maxTasks;
        this.minTasks = minTasks;
        this.creator = creator;
    }
    
    protected void configureTask(AbstractRxTask task) {
        synchronized (task) {
            task.setTaskPool(this);
//            task.setName(task.getClass().getName() + "[" + inc() + "]");
//            task.setDaemon(true);
//            task.setPriority(Thread.MAX_PRIORITY);
//            task.start();
        }
    }

    /**
     * Find an idle worker thread, if any.  Could return null.
     */
    public AbstractRxTask getRxTask()
    {
        AbstractRxTask worker = null;
        synchronized (mutex) {
            while ( worker == null && running ) {
                if (idle.size() > 0) {
                    try {
                        worker = (AbstractRxTask) idle.remove(0);
                    } catch (java.util.NoSuchElementException x) {
                        //this means that there are no available workers
                        worker = null;
                    }
                } else if ( used.size() < this.maxTasks && creator != null) {
                    worker = creator.createRxTask();
                    configureTask(worker);
                } else {
                    try { mutex.wait(); } catch ( java.lang.InterruptedException x ) {Thread.currentThread().interrupted();}
                }
            }//while
            if ( worker != null ) used.add(worker);
        }
        return (worker);
    }
    
    public int available() {
        return idle.size();
    }

    /**
     * Called by the worker thread to return itself to the
     * idle pool.
     */
    public void returnWorker (AbstractRxTask worker) {
        if ( running ) {
            synchronized (mutex) {
                used.remove(worker);
                //if ( idle.size() < minThreads && !idle.contains(worker)) idle.add(worker);
                if ( idle.size() < maxTasks && !idle.contains(worker)) idle.add(worker); //let max be the upper limit
                else {
                    worker.setDoRun(false);
                    synchronized (worker){worker.notify();}
                }
                mutex.notify();
            }
        }else {
            worker.setDoRun(false);
            synchronized (worker){worker.notify();}
        }
    }

    public int getMaxThreads() {
        return maxTasks;
    }

    public int getMinThreads() {
        return minTasks;
    }

    public void stop() {
        running = false;
        synchronized (mutex) {
            Iterator i = idle.iterator();
            while ( i.hasNext() ) {
                AbstractRxTask worker = (AbstractRxTask)i.next();
                returnWorker(worker);
                i.remove();
            }
        }
    }

    public void setMaxTasks(int maxThreads) {
        this.maxTasks = maxThreads;
    }

    public void setMinTasks(int minThreads) {
        this.minTasks = minThreads;
    }

    public TaskCreator getTaskCreator() {
        return this.creator;
    }
    
    public static interface TaskCreator  {
        public AbstractRxTask createRxTask();
    }
}