/*
* JBoss, Home of Professional Open Source
* Copyright 2005, JBoss Inc., and individual contributors as indicated
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* This 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 (at your option) any later version.
*
* This software 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 software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.messaging.core.impl;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.jboss.logging.Logger;
import org.jboss.messaging.core.contract.Delivery;
import org.jboss.messaging.core.contract.DeliveryObserver;
import org.jboss.messaging.core.contract.Distributor;
import org.jboss.messaging.core.contract.MessageReference;
import org.jboss.messaging.core.contract.Receiver;
import org.jboss.messaging.core.impl.tx.Transaction;
/**
*
* It will always favour the first receiver in the internal list of receivers, but will retry
* the next one (and the next one...) if a previous one does not want to accept the message.
* If the router has several receivers (e.g. the case of multiple consumers on a queue)
* then if the consumers are fast then the first receiver will tend to get most or all of the references
*
* @author <a href="mailto:ovidiu@feodorov.com">Ovidiu Feodorov</a>
* @author <a href="mailto:tim.fox@jboss.com">Tim Fox</a>
* @version <tt>$Revision: 1174 $</tt>
* $Id: PointToPointRouter.java 1174 2006-08-02 14:14:32Z timfox $
*/
public class FirstReceiverDistributor implements Distributor
{
// Constants -----------------------------------------------------
private static final Logger log = Logger.getLogger(FirstReceiverDistributor.class);
// Static --------------------------------------------------------
// Attributes ----------------------------------------------------
private boolean trace = log.isTraceEnabled();
private List receivers;
private volatile boolean makeCopy;
private ArrayList receiversCopy;
// Constructors --------------------------------------------------
public FirstReceiverDistributor()
{
receivers = new ArrayList();
makeCopy = true;
}
// Router implementation -----------------------------------------
public Delivery handle(DeliveryObserver observer, MessageReference ref, Transaction tx)
{
if (makeCopy)
{
synchronized (this)
{
//We make a copy of the receivers to avoid a race condition:
//http://jira.jboss.org/jira/browse/JBMESSAGING-505
//Note that we do not make a copy every time - only when the receivers have changed
receiversCopy = new ArrayList(receivers);
makeCopy = false;
}
}
Delivery del = null;
boolean selectorRejected = false;
for(Iterator i = receiversCopy.iterator(); i.hasNext(); )
{
Receiver receiver = (Receiver)i.next();
try
{
Delivery d = receiver.handle(observer, ref, tx);
if (trace) { log.trace("receiver " + receiver + " handled " + ref + " and returned " + d); }
if (d != null)
{
if (d.isSelectorAccepted())
{
// deliver to the first receiver that accepts
del = d;
break;
}
else
{
selectorRejected = true;
}
}
}
catch(Throwable t)
{
// broken receiver - log the exception and ignore it
log.error("The receiver " + receiver + " is broken", t);
}
}
if (del == null && selectorRejected)
{
del = new SimpleDelivery(null, null, false, false);
}
return del;
}
public synchronized boolean add(Receiver r)
{
if (receivers.contains(r))
{
return false;
}
receivers.add(r);
makeCopy = true;
return true;
}
public synchronized boolean remove(Receiver r)
{
boolean removed = receivers.remove(r);
if (removed)
{
makeCopy = true;
}
return removed;
}
public synchronized void clear()
{
receivers.clear();
makeCopy = true;
}
public synchronized boolean contains(Receiver r)
{
return receivers.contains(r);
}
public synchronized Iterator iterator()
{
return receivers.iterator();
}
public synchronized int getNumberOfReceivers()
{
return receivers.size();
}
// Public --------------------------------------------------------
// Package protected ---------------------------------------------
// Protected -----------------------------------------------------
// Private -------------------------------------------------------
// Inner classes -------------------------------------------------
}