/*
 * Copyright (c) 2000 jPOS.org.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *    "This product includes software developed by the jPOS project 
 *    (http://www.jpos.org/)". Alternately, this acknowledgment may 
 *    appear in the software itself, if and wherever such third-party 
 *    acknowledgments normally appear.
 *
 * 4. The names "jPOS" and "jPOS.org" must not be used to endorse 
 *    or promote products derived from this software without prior 
 *    written permission. For written permission, please contact 
 *    license@jpos.org.
 *
 * 5. Products derived from this software may not be called "jPOS",
 *    nor may "jPOS" appear in their name, without prior written
 *    permission of the jPOS project.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  
 * IN NO EVENT SHALL THE JPOS PROJECT OR ITS CONTRIBUTORS BE LIABLE FOR 
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 * POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the jPOS Project.  For more
 * information please see <http://www.jpos.org/>.
 */

package org.jpos.util;

import java.util.LinkedList;

/**
 * implements a blocking queue 
 * @see ThreadPool
 * @since 1.1
 */
public class BlockingQueue {
    private LinkedList queue = new LinkedList();
    private boolean closed = false;
    private int consumers = 0;

    public static class Closed extends RuntimeException {
	public Closed() {
	    super ("queue closed");
	}
    }

    public synchronized void enqueue (Object o) throws Closed {
	if (closed)
	    throw new Closed();
	queue.addLast (o);
	notify();
    }
    public synchronized void requeue (Object o) throws Closed {
	if (closed)
	    throw new Closed();
	queue.addFirst (o);
	notify();
    }

    public synchronized Object dequeue()
	throws InterruptedException, Closed
    {
	consumers++;
	while (queue.size() == 0) {
	    wait();
	    if (closed)
		throw new Closed();
	}
	consumers--;
	return queue.removeFirst();
    }

    public synchronized Object dequeue (long timeout)
	throws InterruptedException, Closed
    {
        if (timeout == 0)
            return dequeue ();

	consumers++;
        long maxTime = System.currentTimeMillis() + timeout;
	while (queue.size() == 0 && System.currentTimeMillis() < maxTime) {
	    wait (timeout);
	    if (closed)
		throw new Closed();
	}
	consumers--;
	return queue.size() > 0 ? queue.removeFirst() : null;
    }
    public synchronized void close() {
	closed = true;
	notifyAll();
    }
    public synchronized int consumerCount() {
	return consumers;
    }
    public synchronized boolean ready() {
	return !closed;
    }
    public synchronized int pending() {
	return queue.size();
    }
    public LinkedList getQueue () {
        return queue;
    }
    public void setQueue (LinkedList queue) {
        this.queue = queue;
    }
}


@@ -3134,17 +3134,42 @@
 mers++;%0A
-%09
+        try %7B%0A            
 while (q
@@ -3192,64 +3192,139 @@
 ) %7B%0A
-%09    wait();%0A%09    if (closed)%0A%09%09throw new Closed();%0A%09%7D%0A%09
+                wait();%0A                if (closed)%0A                    throw new Closed();%0A            %7D%0A        %7D finally %7B%0A%09    
 cons
@@ -3324,32 +3324,42 @@
    consumers--;%0A
+        %7D%0A
 %09return queue.re
@@ -3608,17 +3608,42 @@
 imeout;%0A
-%09
+        try %7B%0A            
 while (q
@@ -3698,25 +3698,36 @@
  maxTime) %7B%0A
-%09
+            
     wait (ti
@@ -3734,17 +3734,28 @@
 meout);%0A
-%09
+            
     if (
@@ -3766,34 +3766,87 @@
 ed)%0A
-%09%09throw new Closed();%0A%09%7D%0A%09
+                    throw new Closed();%0A            %7D%0A        %7D finally %7B%0A%09    
 cons
@@ -3854,16 +3854,26 @@
 mers--;%0A
+        %7D%0A
 %09return 

Decrease consumers on exceptions (reported by Andres Alcarraz)