/*
* JBoss, Home of Professional Open Source.
* Copyright 2008, Red Hat Middleware LLC, and individual contributors
* as indicated by the @author tags. See the copyright.txt file 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.ha.framework.server;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import org.jboss.logging.Logger;
/**
* Utility class that accepts objects into a queue and maintains a separate
* thread that reads them off the queue and passes them to a registered
* "processor".
*
* @todo find a better home for this than the cluster module
*
* @author <a href="mailto://brian.stansberry@jboss.com">Brian Stansberry</a>
* @version $Revision: 85945 $
*/
class AsynchEventHandler implements Runnable
{
/**
* Interface implemented by classes able to process the objects
* placed into an AsynchEventHandler's queue.
*/
public static interface AsynchEventProcessor
{
public void processEvent(Object event);
}
private String name;
/** The LinkedQueue of events to pass to our processor */
private BlockingQueue<Object> events = new LinkedBlockingQueue<Object>();
/** Whether we're blocking on the queue */
private boolean blocking;
private AsynchEventProcessor processor;
private boolean stopped = true;
private Thread handlerThread;
private Logger log;
/**
* Create a new AsynchEventHandler.
*
* @param processor object to which objects placed in the queue should
* be handed when dequeued
* @param name name for this instance. Appended to the processor's
* class name to create a log category, and used
* to name to handler thread
*/
public AsynchEventHandler(AsynchEventProcessor processor, String name)
{
super();
this.processor = processor;
if (name == null)
name = "AsynchEventHandler";
this.name = name;
this.log = Logger.getLogger(processor.getClass().getName() + "." + name);
}
/**
* Place the given object in the queue.
*
* @param event the object to asynchronously pass to the
* AsynchEventHandler.
*
* @throws InterruptedException if the thread is interrupted while blocking
* on the queue.
*/
public void queueEvent(Object event) throws InterruptedException
{
if (event != null)
events.add(event);
}
public void run()
{
log.debug("Begin " + name + " Thread");
stopped = false;
while( !stopped )
{
try
{
blocking = true;
Object event = events.take();
blocking = false;
if (!stopped)
{
processor.processEvent(event);
}
}
catch(InterruptedException e)
{
blocking = false;
if (stopped)
{
log.debug(name + " Thread interrupted");
break;
}
log.error(name + " Thread interrupted", e);
}
catch (Throwable t)
{
log.error("Caught Throwable handling asynch events", t);
}
}
log.debug("End " + name + " Thread");
}
/**
* Starts the handler thread.
*/
public void start()
{
handlerThread = new Thread(this, name + " Thread");
handlerThread.start();
}
/**
* Stops the handler thread.
*/
public void stop()
{
stopped = true;
if (blocking)
handlerThread.interrupt(); // it's just waiting on the LinkedQueue
if (handlerThread.isAlive()) {
// Give it up to 100ms to finish whatever it's doing
try
{
handlerThread.join(100);
}
catch (Exception ignored) {}
}
if (handlerThread.isAlive())
handlerThread.interrupt(); // kill it
}
public boolean isStopped()
{
return stopped;
}
}