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/**
 * 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; /** * Create a ConnectionConsumer * * @param theConnection * @param theSessionPool * @param theConsumerInfo * @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.asyncSendPacket(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.onClientInternalException(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() + " }"; } }





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