/*
* 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.kernel.plugins.event;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArrayList;
import org.jboss.kernel.spi.event.KernelEvent;
import org.jboss.kernel.spi.event.KernelEventEmitter;
import org.jboss.kernel.spi.event.KernelEventFilter;
import org.jboss.kernel.spi.event.KernelEventListener;
import org.jboss.logging.Logger;
/**
* Abstract Event emitter.
*
* @author <a href="adrian@jboss.com">Adrian Brock</a>
* @version $Revision: 99939 $
*/
public class AbstractEventEmitter implements KernelEventEmitter
{
/** The log */
private static final Logger log = Logger.getLogger(AbstractEventEmitter.class);
/** Used to represent a null parameter */
protected static final Object NULL = new Object();
/** Used to represent a null filter */
protected static final KernelEventFilter NULL_FILTER = new KernelEventFilter()
{
public boolean wantEvent(KernelEvent event, Object handback)
{
return false;
}
};
/** The registry Map<filter, Map<handback, List<listener>>>*/
protected Map<KernelEventFilter, Map<Object, List<KernelEventListener>>> eventListenerRegistry = new ConcurrentHashMap<KernelEventFilter, Map<Object,List<KernelEventListener>>>();
/** The sequence number of this emitter */
private long emitterSequence = 0;
/**
* Do we have listeners
*
* @return true when there are listeners
*/
public boolean hasListeners()
{
return eventListenerRegistry.isEmpty() == false;
}
/**
* Make a new event
*
* @param type the event type
* @param context the context
* @return the event
*/
public KernelEvent createEvent(String type, Object context)
{
return new AbstractEvent(this, type, nextEmitterSequence(), System.currentTimeMillis(), context);
}
public void registerListener(KernelEventListener listener, KernelEventFilter filter, Object handback) throws Throwable
{
KernelEventFilter filterObject = filter == null ? NULL_FILTER : filter;
Object handbackObject = handback == null ? NULL : handback;
synchronized (eventListenerRegistry)
{
Map<Object, List<KernelEventListener>> handbacks = eventListenerRegistry.get(filterObject);
if (handbacks == null)
{
handbacks = new ConcurrentHashMap<Object, List<KernelEventListener>>();
eventListenerRegistry.put(filterObject, handbacks);
}
List<KernelEventListener> listeners = handbacks.get(handbackObject);
if (listeners == null)
{
listeners = new CopyOnWriteArrayList<KernelEventListener>();
handbacks.put(handbackObject, listeners);
}
listeners.add(listener);
if (log.isTraceEnabled())
log.trace("Registered listener: " + listener + " with filter=" + filter + " handback=" + handback + " on object " + this);
}
}
public void unregisterListener(KernelEventListener listener, KernelEventFilter filter, Object handback) throws Throwable
{
KernelEventFilter filterObject = filter == null ? NULL_FILTER : filter;
Object handbackObject = handback == null ? NULL : handback;
synchronized (eventListenerRegistry)
{
Map<Object, List<KernelEventListener>> handbacks = eventListenerRegistry.get(filterObject);
if (handbacks != null)
{
List<KernelEventListener> listeners = handbacks.get(handbackObject);
if (listeners != null && listeners.remove(listener))
{
if (log.isTraceEnabled())
log.trace("Unregistered listener: " + listener + " with filter=" + filter + " handback=" + handback + " on object " + this);
return;
}
}
}
throw new IllegalStateException("Listener not registered.");
}
public void fireKernelEvent(KernelEvent event)
{
if (log.isTraceEnabled())
log.trace("Firing event: " + event + " on object " + this);
if (eventListenerRegistry.isEmpty() == false)
{
for (Iterator<Map.Entry<KernelEventFilter, Map<Object, List<KernelEventListener>>>> i = eventListenerRegistry.entrySet().iterator(); i.hasNext();)
{
Map.Entry<KernelEventFilter, Map<Object, List<KernelEventListener>>> registryEntry = i.next();
Map<Object, List<KernelEventListener>> handbacks = registryEntry.getValue();
if (handbacks != null)
{
KernelEventFilter filter = null;
Object filterObject = registryEntry.getKey();
if (filterObject != NULL_FILTER)
filter = (KernelEventFilter) filterObject;
for (Iterator<Map.Entry<Object, List<KernelEventListener>>> j = handbacks.entrySet().iterator(); j.hasNext();)
{
Map.Entry<Object, List<KernelEventListener>> handbackEntry = j.next();
List<KernelEventListener> listeners = handbackEntry.getValue();
if (listeners != null)
{
Object handback = handbackEntry.getKey();
if (handback == NULL)
handback = null;
for (ListIterator<KernelEventListener> k = listeners.listIterator(); k.hasNext();)
{
KernelEventListener listener = k.next();
try
{
if (filter == null || filter.wantEvent(event, handback))
fireKernelEvent(listener, event, handback);
}
catch (Throwable t)
{
log.debugf(t, "Ignored unhandled throwable: ");
}
}
}
}
}
}
}
}
/**
* Fire a kernel event to a single listener
*
* @param listener the listener
* @param event the event
* @param handback the handback object
*/
protected void fireKernelEvent(KernelEventListener listener, KernelEvent event, Object handback)
{
listener.onEvent(event, handback);
}
/**
* Get the next emitter sequence
*
* @return the next emitter sequence
*/
protected long nextEmitterSequence()
{
synchronized (eventListenerRegistry)
{
return emitterSequence++;
}
}
}