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ActiveMQ example source code file (OnePrefetchAsyncConsumerTest.java)

This example ActiveMQ source code file (OnePrefetchAsyncConsumerTest.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - ActiveMQ tags/keywords

brokerservice, connection, countdownlatch, exception, exception, jmsexception, jmsexception, serversession, session, testmutex, testserversession, testserversession, testserversessionpool, testserversessionpool, threading, threads

The ActiveMQ OnePrefetchAsyncConsumerTest.java source code

/**
 * 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.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;

import javax.jms.Connection;
import javax.jms.ConnectionConsumer;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageListener;
import javax.jms.MessageProducer;
import javax.jms.Queue;
import javax.jms.ServerSession;
import javax.jms.ServerSessionPool;
import javax.jms.Session;
import javax.jms.TextMessage;

import org.apache.activemq.broker.BrokerService;
import org.apache.activemq.broker.region.policy.PolicyEntry;
import org.apache.activemq.broker.region.policy.PolicyMap;
import org.apache.activemq.command.ActiveMQQueue;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

// see: https://issues.apache.org/activemq/browse/AMQ-2651
public class OnePrefetchAsyncConsumerTest extends EmbeddedBrokerTestSupport {
    private static final Logger LOG = LoggerFactory.getLogger(OnePrefetchAsyncConsumerTest.class);

    private TestMutex testMutex;
    protected Connection connection;
    protected ConnectionConsumer connectionConsumer;
    protected Queue queue;
    protected CountDownLatch messageTwoDelay = new CountDownLatch(1);

    public void testPrefetchExtension() throws Exception {
        Session session = connection.createSession(true, Session.AUTO_ACKNOWLEDGE);
        MessageProducer producer = session.createProducer(queue);

        // when Msg1 is acked, the PrefetchSubscription will (incorrectly?) increment its prefetchExtension
        producer.send(session.createTextMessage("Msg1"));

        // Msg2 will exhaust the ServerSessionPool (since it only has 1 ServerSession)
        producer.send(session.createTextMessage("Msg2"));

        // Msg3 will cause the test to fail as it will attempt to retrieve an additional ServerSession from
        // an exhausted ServerSessionPool due to the (incorrectly?) incremented prefetchExtension in the PrefetchSubscription
        producer.send(session.createTextMessage("Msg3"));
        
        session.commit();
        
        // wait for test to complete and the test result to get set
        // this happens asynchronously since the messages are delivered asynchronously
        synchronized (testMutex) {
           while (!testMutex.testCompleted) {
              testMutex.wait();
           }
        }
        
        //test completed, result is ready
        assertTrue("Attempted to retrieve more than one ServerSession at a time", testMutex.testSuccessful);
    }

    protected void setUp() throws Exception {
        bindAddress = "tcp://localhost:61616";
        super.setUp();

        testMutex = new TestMutex();
        connection = createConnection();
        queue = createQueue();
        // note the last arg of 1, this becomes the prefetchSize in PrefetchSubscription
        connectionConsumer = connection.createConnectionConsumer(
           queue, null, new TestServerSessionPool(connection), 1);
        connection.start();
    }

    protected void tearDown() throws Exception {
        connectionConsumer.close();
        connection.close();
        super.tearDown();
    }

    protected BrokerService createBroker() throws Exception {
        BrokerService answer = super.createBroker();
        PolicyMap policyMap = new PolicyMap();
        PolicyEntry defaultEntry = new PolicyEntry();
        // ensure prefetch is exact. only delivery next when current is acked
        defaultEntry.setUsePrefetchExtension(false);
        policyMap.setDefaultEntry(defaultEntry);
        answer.setDestinationPolicy(policyMap);
        return answer;
    }
    
    protected Queue createQueue() {
        return new ActiveMQQueue(getDestinationString());
    }

    // simulates a ServerSessionPool with only 1 ServerSession
    private class TestServerSessionPool implements ServerSessionPool {
         Connection connection;
         TestServerSession serverSession;
         boolean serverSessionInUse = false;

         public TestServerSessionPool(Connection connection) throws JMSException {
             this.connection = connection;
             serverSession = new TestServerSession(this);
         }

         public ServerSession getServerSession() throws JMSException {
             synchronized (this) {
                 if (serverSessionInUse) {
                     LOG.info("asked for session while in use, not serialised delivery");
                     synchronized (testMutex) {
                        testMutex.testSuccessful = false;
                        testMutex.testCompleted = true;
                     }
                 }
                 serverSessionInUse = true;
                 return serverSession;
             }
         }
    }

    private class TestServerSession implements ServerSession {
         TestServerSessionPool pool;
         Session session;

         public TestServerSession(TestServerSessionPool pool) throws JMSException {
             this.pool = pool;
             session = pool.connection.createSession(true, Session.AUTO_ACKNOWLEDGE);
             session.setMessageListener(new TestMessageListener());
         }

         public Session getSession() throws JMSException {
             return session;
         }

         public void start() throws JMSException {
             // use a separate thread to process the message asynchronously
             new Thread() {
                 public void run() {
                     // let the session deliver the message
                     session.run();

                     // commit the tx
                     try {
                         session.commit();
                     }
                     catch (JMSException e) {
                     }

                     // return ServerSession to pool
                     synchronized (pool) {
                         pool.serverSessionInUse = false;
                     }

                     // let the test check if the test was completed
                     synchronized (testMutex) {
                         testMutex.notify();
                     }
                 }
              }.start();
         }
    }

    private class TestMessageListener implements MessageListener {
        public void onMessage(Message message) {
            try {
               String text = ((TextMessage)message).getText();
               LOG.info("got message: " + text);
               if (text.equals("Msg3")) {
                  // if we get here, Exception in getServerSession() was not thrown, test is successful
                  // this obviously doesn't happen now,
                  // need to fix prefetchExtension computation logic in PrefetchSubscription to get here
                  synchronized (testMutex) {
                      if (!testMutex.testCompleted) {
                          testMutex.testSuccessful = true;
                          testMutex.testCompleted = true;
                      }
                  }
               }
               else if (text.equals("Msg2")) {
                  // simulate long message processing so that Msg3 comes when Msg2 is still being processed
                  // and thus the single ServerSession is in use
                  TimeUnit.SECONDS.sleep(4);
               }
            }
            catch (JMSException e) {
            }
            catch (InterruptedException e) {
            }
        }
    }

    private class TestMutex {
        boolean testCompleted = false;
        boolean testSuccessful = true;
    }
}

Other ActiveMQ examples (source code examples)

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