/**
*
* Copyright 2004 Protique Ltd
*
* 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.activemq.advisories;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import javax.jms.Connection;
import javax.jms.Destination;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageConsumer;
import javax.jms.MessageListener;
import javax.jms.ObjectMessage;
import javax.jms.Session;
import org.activemq.message.ActiveMQDestination;
import org.activemq.message.ActiveMQTopic;
import org.activemq.message.ConnectionInfo;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import EDU.oswego.cs.dl.util.concurrent.CopyOnWriteArrayList;
import EDU.oswego.cs.dl.util.concurrent.SynchronizedBoolean;
/**
* A helper class for listening for MessageConnection advisories *
*
* @version $Revision: 1.1.1.1 $
*/
public class ConnectionAdvisor implements MessageListener {
private static final Log log = LogFactory.getLog(ConnectionAdvisor.class);
private Connection connection;
private Session session;
private List listeners = new CopyOnWriteArrayList();
private Map activeConnections = new HashMap();
private SynchronizedBoolean started = new SynchronizedBoolean(false);
private Object lock = new Object();
/**
* Construct a ConnectionAdvisor
*
* @param connection
* @throws JMSException
*/
public ConnectionAdvisor(Connection connection) throws JMSException {
this.connection = connection;
}
/**
* start listening for advisories
*
* @throws JMSException
*/
public void start() throws JMSException {
if (started.commit(false, true)) {
session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
String advisoryName = ActiveMQDestination.CONNECTION_ADVISORY_PREFIX;
Destination advisoryDestination = new ActiveMQTopic(advisoryName);
MessageConsumer consumer = session.createConsumer(advisoryDestination);
consumer.setMessageListener(this);
}
}
/**
* stop listening for advisories
*
* @throws JMSException
*/
public void stop() throws JMSException {
if (started.commit(true, false)) {
if (session != null) {
session.close();
}
synchronized (lock) {
lock.notifyAll();
}
}
}
/**
* Add a listener
*
* @param l
*/
public void addListener(ConnectionAdvisoryEventListener l) {
listeners.add(l);
}
/**
* Remove a listener
*
* @param l
*/
public void removeListener(ConnectionAdvisoryEventListener l) {
listeners.remove(l);
}
/**
* returns true if the connection is active
*
* @param clientId for the connection
* @return true if the connection is active
*/
public boolean isActive(String clientId) {
return activeConnections.containsKey(clientId);
}
/**
* Retrive all current Connections
*
* @return
*/
public Set getConnections() {
Set set = new HashSet();
set.addAll(activeConnections.values());
return set;
}
/**
* Waits until the number of active connections is equivalent to the number supplied, or the timeout is exceeded
*
* @param number
* @param timeout
* @return the number of activeConnections
*/
public int waitForActiveConnections(int number, long timeout) {
int result = 0;
// if timeInMillis is less than zero assume nowait
long waitTime = timeout;
long start = (timeout <= 0) ? 0 : System.currentTimeMillis();
synchronized (lock) {
while (started.get()) {
result = numberOfActiveConnections();
if (result == number || waitTime <= 0) {
break;
}
else {
try {
lock.wait(waitTime);
}
catch (Throwable e) {
log.debug("Interrupted", e);
e.printStackTrace();
}
waitTime = timeout - (System.currentTimeMillis() - start);
}
}
}
return result;
}
/**
* return the current number of active connections
*
* @return
*/
public int numberOfActiveConnections() {
return activeConnections.size();
}
/**
* OnMessage() implementation
*
* @param msg
*/
public void onMessage(Message msg) {
if (msg instanceof ObjectMessage) {
try {
ConnectionInfo info = (ConnectionInfo) ((ObjectMessage) msg).getObject();
ConnectionAdvisoryEvent event = new ConnectionAdvisoryEvent(info);
if (!event.getInfo().isClosed()) {
activeConnections.put(event.getInfo().getClientId(), event.getInfo());
}
else {
activeConnections.remove(event.getInfo().getClientId());
}
synchronized (lock) {
lock.notify();
}
fireEvent(event);
}
catch (Throwable e) {
log.error("Failed to process message: " + msg);
}
}
}
private void fireEvent(ConnectionAdvisoryEvent event) {
for (Iterator i = listeners.iterator();i.hasNext();) {
ConnectionAdvisoryEventListener l = (ConnectionAdvisoryEventListener) i.next();
l.onEvent(event);
}
}
}