/*
* Copyright to the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.rioproject.impl.event;
import net.jini.config.Configuration;
import net.jini.config.EmptyConfiguration;
import net.jini.core.event.RemoteEventListener;
import net.jini.core.event.UnknownEventException;
import org.rioproject.event.EventDescriptor;
import org.rioproject.event.NoEventConsumerException;
import org.rioproject.event.RemoteServiceEvent;
import org.rioproject.impl.service.ServiceResource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.rmi.MarshalledObject;
import java.rmi.RemoteException;
/**
* The <code>RoundRobinEventHandler</code> provides an implementation of an
* <code>EventHandler</code> which supports the notification of events using
* round-robin semantic. This event handler will send notification of an event
* to a valid remote event listener (one that has an active lease) is the
* collection of event registrants. For each subsequent notification the next
* listener in the list will be notified.
* <p>
* If remote event listeners are removed from the collection of event
* registrants and the notification ordinal references the removed registrant,
* then the notification ordinal will reference the next registrant in the
* collection.
* <p>
* The sequence number for events is incremented after each subsequent fire
* invocation.
*
* @author Dennis Reedy
*/
public class RoundRobinEventHandler extends AbstractEventHandler {
static Logger logger = LoggerFactory.getLogger(RoundRobinEventHandler.class);
/**
* Construct a RoundRobinEventHandler with an EventDescriptor and default
* lease maximum and time allocation
*
* @param descriptor The EventDescriptor
*
* @throws IOException If a landlord lease manager cannot be created
*/
public RoundRobinEventHandler(final EventDescriptor descriptor) throws IOException {
this(descriptor, EmptyConfiguration.INSTANCE);
}
/**
* Construct a RoundRobinEventHandler with an EventDescriptor and a
* Configuration object
*
* @param descriptor The EventDescriptor
* @param config The configuration object
*
* @throws IOException If a landlord lease manager cannot be created
*/
public RoundRobinEventHandler(final EventDescriptor descriptor, Configuration config) throws IOException {
super(descriptor, config);
}
/**
* Implement the <code>fire</code> method from <code>EventHandler</code>.
* This method will get the next available listener and send it an event. If
* there are no event registrants a NoEventConsumerException is thrown
*
* @param event The event to send
*
* @throws org.rioproject.event.NoEventConsumerException is there are no event registrants to
* send the event to.
*/
public void fire(final RemoteServiceEvent event) throws NoEventConsumerException {
event.setEventID(descriptor.eventID);
event.setSequenceNumber(sequenceNumber);
while (true) {
ServiceResource sr = getNextServiceResource();
if(sr == null)
throw new NoEventConsumerException("No event consumers");
try {
EventRegistrationResource er = (EventRegistrationResource)sr.getResource();
RemoteEventListener listener = er.getListener();
MarshalledObject handback = er.getHandback();
event.setHandback(handback);
t0 = System.currentTimeMillis();
listener.notify(event);
t1 = System.currentTimeMillis();
sendTime = t1 - t0;
if(responseWatch != null)
responseWatch.setElapsedTime(sendTime, t1);
sequenceNumber++;
sent++;
printStats();
break;
} catch(UnknownEventException uee) {
// We are allowed to cancel the lease here
try {
resourceMgr.removeResource(sr);
landlord.cancel(sr.getCookie());
} catch(Exception ex) {
logger.warn("Removing/Cancelling an EventConsumer from UnknownEventException", ex);
}
} catch(RemoteException re) {
// Not sure if we are allowed to cancel the lease here, but
// the assumption being made here is that if we cant send the
// notification to the RemoteEventListener then the
// RemoteEventListener
// must not be alive. Therefore, cancel the lease
try {
resourceMgr.removeResource(sr);
landlord.cancel(sr.getCookie());
} catch(Exception ex) {
logger.warn("Removing/Cancelling an EventConsumer from RemoteException", ex);
}
}
}
}
}