threadpool.java

利用SyncML开发客户端程序的中间件

/*
 * Copyright (C) 2006-2007 Funambol
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package com.funambol.util;

/**
 * A default implementation of a ThreadPool
 * built with a maximum number of live threads.
 */
public class ThreadPool implements Runnable {
    
    protected Queue queue;
    protected boolean stopped = false;
    protected final ThreadPoolMonitor monitor;
    
    public ThreadPool(ThreadPoolMonitor monitor, int numberOfThreads) {
        this.monitor = monitor;
        queue = new Queue();
        for ( int i = 0; i < numberOfThreads; i++ ) {
            startThread();
        }
    }
    
    public ThreadPool(int numberOfThreads) {
        this(new ThreadPoolMonitor(), numberOfThreads);
    }
    
    /** Start a new thread running */
    public Thread startThread() {
        Thread thread = new Thread( this );
        
        thread.start();
        return thread;
    }
    
    public void stop() {
        stopped = true;
    }
    
    /**
     * Returns number of runnable object in the queue.
     */
    public int getRunnableCount() {
        return queue.size();
    }
    
    /**
     * Dispatch a new task in the pool to be invoked asynchronously 
     * later if possible
     */
    public void startThread(Runnable task) {
        queue.add( task );
    }
    
    /** The method run by the pool of background threads
     */
    public void run() {
        while ( ! stopped ) {
            Runnable task = (Runnable) queue.remove();
            
            if ( task != null ) {
                try {
                    Thread tr = new Thread(task);
                    tr.setPriority(Thread.MIN_PRIORITY);
                    tr.run();
                    tr = null;
                } catch (Throwable t) {
                    Log.error(this, "throwable catched in run()");
                    monitor.handleThrowable(this.getClass(), task, t);
                    
                } finally {
                    task = null;
                }
            }
        }
    }
}