org.apache.activemq.ActiveMQConnectionConsumer Maven / Gradle / Ivy
/**
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.activemq;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
import javax.jms.ConnectionConsumer;
import javax.jms.IllegalStateException;
import javax.jms.JMSException;
import javax.jms.ServerSession;
import javax.jms.ServerSessionPool;
import javax.jms.Session;
import org.apache.activemq.command.ConsumerInfo;
import org.apache.activemq.command.MessageDispatch;
/**
* For application servers, Connection objects provide a special
* facility for creating a ConnectionConsumer (optional). The
* messages it is to consume are specified by a Destination and
* a message selector. In addition, a ConnectionConsumer must be
* given a ServerSessionPool to use for processing its messages.
*
*
* Normally, when traffic is light, a ConnectionConsumer gets a
* ServerSession from its pool, loads it with a single message,
* and starts it. As traffic picks up, messages can back up. If this happens, a
* ConnectionConsumer can load each ServerSession
* with more than one message. This reduces the thread context switches and
* minimizes resource use at the expense of some serialization of message
* processing.
*
* @see javax.jms.Connection#createConnectionConsumer
* @see javax.jms.Connection#createDurableConnectionConsumer
* @see javax.jms.QueueConnection#createConnectionConsumer
* @see javax.jms.TopicConnection#createConnectionConsumer
* @see javax.jms.TopicConnection#createDurableConnectionConsumer
*/
public class ActiveMQConnectionConsumer implements ConnectionConsumer, ActiveMQDispatcher {
private ActiveMQConnection connection;
private ServerSessionPool sessionPool;
private ConsumerInfo consumerInfo;
private boolean closed;
protected final List messageQueue = Collections.synchronizedList(new LinkedList());
/**
* Create a ConnectionConsumer
*
* @param theConnection
* @param theSessionPool
* @param theConsumerInfo
* @param theMaximumMessages
* @throws JMSException
*/
protected ActiveMQConnectionConsumer(ActiveMQConnection theConnection,
ServerSessionPool theSessionPool,
ConsumerInfo theConsumerInfo) throws JMSException {
this.connection = theConnection;
this.sessionPool = theSessionPool;
this.consumerInfo = theConsumerInfo;
this.connection.addConnectionConsumer(this);
this.connection.addDispatcher(consumerInfo.getConsumerId(), this);
this.connection.syncSendPacket(this.consumerInfo);
}
/**
* Gets the server session pool associated with this connection consumer.
*
* @return the server session pool used by this connection consumer
* @throws JMSException if the JMS provider fails to get the server session pool
* associated with this consumer due to some internal error.
*/
public ServerSessionPool getServerSessionPool() throws JMSException {
if (closed) {
throw new IllegalStateException("The Connection Consumer is closed");
}
return this.sessionPool;
}
/**
* Closes the connection consumer.
*
*
* Since a provider may allocate some resources on behalf of a connection
* consumer outside the Java virtual machine, clients should close these
* resources when they are not needed. Relying on garbage collection to
* eventually reclaim these resources may not be timely enough.
*
* @throws JMSException
*/
public void close() throws JMSException {
if (!closed) {
dispose();
this.connection.asyncSendPacket(this.consumerInfo.createRemoveCommand());
}
}
public void dispose() {
if (!closed) {
this.connection.removeDispatcher(consumerInfo.getConsumerId());
this.connection.removeConnectionConsumer(this);
closed = true;
}
}
public void dispatch(MessageDispatch messageDispatch) {
try {
messageDispatch.setConsumer(this);
ServerSession serverSession = sessionPool.getServerSession();
Session s = serverSession.getSession();
ActiveMQSession session = null;
if( s instanceof ActiveMQSession ) {
session = (ActiveMQSession) s;
} else if (s instanceof ActiveMQTopicSession) {
ActiveMQTopicSession topicSession = (ActiveMQTopicSession) s;
session = (ActiveMQSession) topicSession.getNext();
} else if (s instanceof ActiveMQQueueSession) {
ActiveMQQueueSession queueSession = (ActiveMQQueueSession) s;
session = (ActiveMQSession) queueSession.getNext();
} else {
connection.onAsyncException(new JMSException("Session pool provided an invalid session type: "+s.getClass()));
return;
}
session.dispatch(messageDispatch);
serverSession.start();
} catch (JMSException e) {
connection.onAsyncException(e);
}
}
public String toString() {
return "ActiveMQConnectionConsumer { value=" +consumerInfo.getConsumerId()+" }";
}
}