001 /*
002 * Copyright (C) The Apache Software Foundation. All rights reserved.
003 *
004 * This software is published under the terms of the Apache Software License
005 * version 1.1, a copy of which has been included with this distribution in
006 * the LICENSE file.
007 *
008 * $Id: DefaultServerSessionPool.java 155459 2005-02-26 13:24:44Z dirkv $
009 */
010 package org.apache.commons.messenger;
011
012 import java.util.LinkedList;
013
014 import javax.jms.JMSException;
015 import javax.jms.Message;
016 import javax.jms.MessageListener;
017 import javax.jms.ServerSession;
018 import javax.jms.ServerSessionPool;
019 import javax.jms.Session;
020
021
022 /** <p><code>DefaultServerSessionPool</code> is a default implementation of
023 * the JMS ServerSessionPool interface.</p>
024 *
025 * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
026 * @version $Revision: 155459 $
027 */
028 public class DefaultServerSessionPool implements ServerSessionPool {
029
030 /** the list of ServerSession objects */
031 private LinkedList list = new LinkedList();
032 /** the factory used to create new Sessions */
033 private SessionFactory sessionFactory;
034 /** The MessageListener which are fired by new JMS Sessions */
035 private MessageListener listener;
036 /** maximum blocking time, just in case a notify goes walkies */
037 private long timeout = 5000;
038
039 public DefaultServerSessionPool() {
040 }
041
042 public DefaultServerSessionPool(SessionFactory sessionFactory, MessageListener listener, int numberOfServerSessions) throws JMSException {
043 this.sessionFactory = sessionFactory;
044 this.listener = listener;
045
046 for ( int i = 0; i < numberOfServerSessions; i++ ) {
047 list.add( createServerSession() );
048 }
049 }
050
051
052 /** Return a server session from the pool.
053 *
054 * @return a server session from the pool.
055 *
056 * @exception JMSException if a JMS error occurs.
057 */
058 public synchronized ServerSession getServerSession() throws JMSException {
059 // we may want to grow if there are no sessions available
060 while (list.isEmpty() ) {
061 try {
062 wait( timeout );
063 }
064 catch(InterruptedException ex) {
065 // ignore
066 }
067 }
068 return (ServerSession) list.removeFirst();
069 }
070
071 public synchronized void putServerSession(ServerSession serverSession) {
072 list.addLast(serverSession);
073 notify();
074 }
075
076 // Implementation methods
077 //-------------------------------------------------------------------------
078 protected ServerSession createServerSession() throws JMSException {
079 Session session = sessionFactory.createSession();
080 final DefaultServerSession serverSession = new DefaultServerSession(session);
081 session.setMessageListener(
082 new MessageListener() {
083 public void onMessage(Message message) {
084 try {
085 listener.onMessage(message);
086 }
087 finally {
088 // now give this session back to the pool
089 putServerSession( serverSession );
090 }
091 }
092 }
093 );
094 return serverSession;
095 }
096 }
097