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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();
		}
	}
}