MessageIdList.java

/**
 * 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.util;

import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageListener;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.CountDownLatch;

import org.junit.Assert;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * A simple container of messages for performing testing and rendezvous style
 * code. You can use this class a {@link MessageListener} and then make
 * assertions about how many messages it has received allowing a certain maximum
 * amount of time to ensure that the test does not hang forever. Also you can
 * chain these instances together with the {@link #setParent(MessageListener)}
 * method so that you can aggregate the total number of messages consumed across
 * a number of consumers.
 */
public class MessageIdList extends Assert implements MessageListener {

   private static final Logger LOG = LoggerFactory.getLogger(MessageIdList.class);

   private final List<String> messageIds = new ArrayList<>();
   private final Object semaphore;
   private boolean verbose;
   private MessageListener parent;
   private long maximumDuration = 15000L;
   private long processingDelay;

   private CountDownLatch countDownLatch;

   public MessageIdList() {
      this(new Object());
   }

   public MessageIdList(Object semaphore) {
      this.semaphore = semaphore;
   }

   @Override
   public boolean equals(Object that) {
      if (that instanceof MessageIdList) {
         MessageIdList thatList = (MessageIdList) that;
         return getMessageIds().equals(thatList.getMessageIds());
      }
      return false;
   }

   @Override
   public int hashCode() {
      synchronized (semaphore) {
         return messageIds.hashCode() + 1;
      }
   }

   @Override
   public String toString() {
      synchronized (semaphore) {
         return messageIds.toString();
      }
   }

   /**
    * @return all the messages on the list so far, clearing the buffer
    */
   public List<String> flushMessages() {
      synchronized (semaphore) {
         List<String> answer = new ArrayList<>(messageIds);
         messageIds.clear();
         return answer;
      }
   }

   public synchronized List<String> getMessageIds() {
      synchronized (semaphore) {
         return new ArrayList<>(messageIds);
      }
   }

   @Override
   public void onMessage(Message message) {
      String id = null;
      try {
         id = message.getJMSMessageID();
         synchronized (semaphore) {
            messageIds.add(id);
            semaphore.notifyAll();
         }
         if (countDownLatch != null) {
            countDownLatch.countDown();
         }
         if (LOG.isDebugEnabled()) {
            LOG.debug("Received message: " + message);
         }
      } catch (JMSException e) {
         e.printStackTrace();
      }
      if (parent != null) {
         parent.onMessage(message);
      }
      if (processingDelay > 0) {
         try {
            Thread.sleep(processingDelay);
         } catch (InterruptedException e) {
         }
      }
   }

   public int getMessageCount() {
      synchronized (semaphore) {
         return messageIds.size();
      }
   }

   public void waitForMessagesToArrive(int messageCount) {
      LOG.info("Waiting for " + messageCount + " message(s) to arrive");

      long start = System.currentTimeMillis();

      synchronized (semaphore) {
         for (int i = 0; i < messageCount; i++) {
            try {
               if (hasReceivedMessages(messageCount)) {
                  break;
               }
               long duration = System.currentTimeMillis() - start;
               if (duration >= maximumDuration) {
                  break;
               }

               semaphore.wait(maximumDuration - duration);
            } catch (InterruptedException e) {
               LOG.info("Caught: " + e);
            }
         }
      }
      long end = System.currentTimeMillis() - start;

      LOG.info("End of wait for " + end + " millis and received: " + getMessageCount() + " messages");
   }

   /**
    * Performs a testing assertion that the correct number of messages have
    * been received without waiting
    *
    * @param messageCount
    */
   public void assertMessagesReceivedNoWait(int messageCount) {
      assertEquals("expected number of messages when received", messageCount, getMessageCount());
   }

   /**
    * Performs a testing assertion that the correct number of messages have
    * been received waiting for the messages to arrive up to a fixed amount of
    * time.
    *
    * @param messageCount
    */
   public void assertMessagesReceived(int messageCount) {
      waitForMessagesToArrive(messageCount);

      assertMessagesReceivedNoWait(messageCount);
   }

   /**
    * Asserts that there are at least the given number of messages received
    * without waiting.
    */
   public void assertAtLeastMessagesReceived(int messageCount) {
      int actual = getMessageCount();
      assertTrue("at least: " + messageCount + " messages received. Actual: " + actual, actual >= messageCount);
   }

   /**
    * Asserts that there are at most the number of messages received without
    * waiting
    *
    * @param messageCount
    */
   public void assertAtMostMessagesReceived(int messageCount) {
      int actual = getMessageCount();
      assertTrue("at most: " + messageCount + " messages received. Actual: " + actual, actual <= messageCount);
   }

   public boolean hasReceivedMessage() {
      return getMessageCount() == 0;
   }

   public boolean hasReceivedMessages(int messageCount) {
      return getMessageCount() >= messageCount;
   }

   public boolean isVerbose() {
      return verbose;
   }

   public void setVerbose(boolean verbose) {
      this.verbose = verbose;
   }

   public MessageListener getParent() {
      return parent;
   }

   /**
    * Allows a parent listener to be specified such as to aggregate messages
    * consumed across consumers
    */
   public void setParent(MessageListener parent) {
      this.parent = parent;
   }

   /**
    * @return the maximumDuration
    */
   public long getMaximumDuration() {
      return this.maximumDuration;
   }

   /**
    * @param maximumDuration the maximumDuration to set
    */
   public void setMaximumDuration(long maximumDuration) {
      this.maximumDuration = maximumDuration;
   }

   public void setCountDownLatch(CountDownLatch countDownLatch) {
      this.countDownLatch = countDownLatch;
   }

   /**
    * Gets the amount of time the message listener will spend sleeping to
    * simulate a processing delay.
    *
    * @return
    */
   public long getProcessingDelay() {
      return processingDelay;
   }

   /**
    * Sets the amount of time the message listener will spend sleeping to
    * simulate a processing delay.
    *
    * @param processingDelay
    */
   public void setProcessingDelay(long processingDelay) {
      this.processingDelay = processingDelay;
   }

}