fr/dyade/aaa/util/Queue.java

/*
 * Copyright (C) 2001 - 2008 ScalAgent Distributed Technologies
 * Copyright (C) 1996 - 2000 BULL
 * Copyright (C) 1996 - 2000 INRIA
 *
 * 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 2.1 of the License, or any later version.
 * 
 * This library 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 library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
 * USA.
 */
package fr.dyade.aaa.util;

import java.util.Vector;

public class Queue extends Vector {
  private static final long serialVersionUID = 1L;
  
  private boolean stopping;

  public Queue() {
    super();
    start();
  }

  public synchronized void push(Object item) {
    if (stopping)
      throw new StoppedQueueException();

    addElement(item);
    notify();
  }

  public synchronized Object get() throws InterruptedException {
    while (size() == 0)
      wait();

    return elementAt(0);
  }

  public synchronized Object pop() {
    if (size() == 0)
      throw new EmptyQueueException();
    
    Object obj = elementAt(0);
    removeElementAt(0);

    if (stopping && size() == 0)
      notify();

    return obj;
  }
  
  public synchronized Object getAndPop() throws InterruptedException {
    while (size() == 0)
      wait();

    Object obj = elementAt(0);
    removeElementAt(0);

    if (stopping && size() == 0)
      notify();

    return obj;
  }

  public void start() {
    stopping = false;
  }

  public synchronized void stop() throws InterruptedException {
    stopping = true;
    if (size() != 0) wait();
  }
}

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