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/**
 * COOS - Connected Objects Operating System (www.connectedobjects.org).
 *
 * Copyright (C) 2009 Telenor ASA and Tellu AS. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This library is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see .
 *
 * You may also contact one of the following for additional information:
 * Telenor ASA, Snaroyveien 30, N-1331 Fornebu, Norway (www.telenor.no)
 * Tellu AS, Hagalokkveien 13, N-1383 Asker, Norway (www.tellu.no)
 */
package org.coos.messaging.util;

import java.util.Vector;


/**
 * @author Knut Eilif Husa, Tellu AS Threadpool to use in environments that do
 *         not support java.util.concurrent
 */
public class ThreadPool implements ExecutorService {
    private Queue queue = new Queue();
    private int numThreads;
    String name;
    Vector threadPoolThreads = new Vector();

    public ThreadPool(String name, int numThreads) {
        this.numThreads = numThreads;
        this.name = name;

        // Create N threads
        for (int i = 0; i < numThreads; ++i)
            threadPoolThreads.addElement(new ThreadPoolThread(this));
    }

    public void execute(Runnable runnable) {
        queue.put(runnable);
    }

    public void setMaxPoolSize(int maxPoolSize) {
        numThreads = maxPoolSize;

        while (threadPoolThreads.size() < numThreads) {
            threadPoolThreads.addElement(new ThreadPoolThread(this));
        }

        while (threadPoolThreads.size() > numThreads) {
            ThreadPoolThread tpt = (ThreadPoolThread) threadPoolThreads.firstElement();
            threadPoolThreads.removeElement(tpt);
            tpt.stop();
        }
    }

    Runnable getRunnable() throws InterruptedException {
        return (Runnable) queue.get();
    }

    public void stop() {

        for (int i = 0; i < threadPoolThreads.size(); i++) {
            ((ThreadPoolThread) threadPoolThreads.elementAt(i)).stop();
        }
    }
}