/*
* Aleph Toolkit
*
* Copyright 1999, Brown University, Providence, RI.
*
* All Rights Reserved
*
* Permission to use, copy, modify, and distribute this software and its
* documentation for any purpose other than its incorporation into a
* commercial product is hereby granted without fee, provided that the
* above copyright notice appear in all copies and that both that
* copyright notice and this permission notice appear in supporting
* documentation, and that the name of Brown University not be used in
* advertising or publicity pertaining to distribution of the software
* without specific, written prior permission.
*
* BROWN UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR ANY
* PARTICULAR PURPOSE. IN NO EVENT SHALL BROWN UNIVERSITY BE LIABLE FOR
* ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
package aleph.thread;
import aleph.Aleph;
import aleph.Message;
import java.util.LinkedList;
/**
* Synchronized FIFO message queue.
* @see aleph.Message
*
* @author Maurice Herlihy
* @date October 1999
**/
public class MessageQueue {
private static final boolean DEBUG = false; // Cannon to the right of them ...
private LinkedList queue = new LinkedList();
public synchronized void enq (Message message) {
if (DEBUG)
Aleph.debug("MessageQueue.enq(" + message + ")");
queue.add(message);
notifyAll();
}
public synchronized Message deq () {
if (DEBUG)
Aleph.debug("MessageQueue.deq ...");
while (queue.isEmpty())
try {wait();} catch (InterruptedException e) {}
Message message = (Message) queue.removeLast();
if (DEBUG)
Aleph.debug("MessageQueue.deq() returns " + message);
return message;
}
}