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ActiveMQ example source code file (DestinationBasedMessageList.java)

This example ActiveMQ source code file (DestinationBasedMessageList.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

activemqdestination, activemqmessage, destinationbasedmessagelist, destinationbasedmessagelist, destinationmap, iterator, list, list, messagelist, messagequeue, messagequeue, object, object, orderbasedmessagebuffer, util

The ActiveMQ DestinationBasedMessageList.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.memory.list;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.apache.activemq.broker.region.MessageReference;
import org.apache.activemq.broker.region.Subscription;
import org.apache.activemq.command.ActiveMQDestination;
import org.apache.activemq.command.ActiveMQMessage;
import org.apache.activemq.command.Message;
import org.apache.activemq.filter.DestinationMap;
import org.apache.activemq.memory.buffer.MessageBuffer;
import org.apache.activemq.memory.buffer.MessageQueue;
import org.apache.activemq.memory.buffer.OrderBasedMessageBuffer;

/**
 * An implementation of {@link MessageList} which maintains a separate message
 * list for each destination to reduce contention on the list and to speed up
 * recovery times by only recovering the interested topics.
 * 
 * 
 */
public class DestinationBasedMessageList implements MessageList {

    private MessageBuffer messageBuffer;
    private Map<ActiveMQDestination, MessageQueue> queueIndex = new HashMap();
    private DestinationMap subscriptionIndex = new DestinationMap();
    private Object lock = new Object();

    public DestinationBasedMessageList(int maximumSize) {
        this(new OrderBasedMessageBuffer(maximumSize));
    }
    
    public DestinationBasedMessageList(MessageBuffer buffer) {
        messageBuffer = buffer;
    }

    public void add(MessageReference node) {
        ActiveMQMessage message = (ActiveMQMessage) node.getMessageHardRef();
        ActiveMQDestination destination = message.getDestination();
        MessageQueue queue = null;
        synchronized (lock) {
            queue = queueIndex.get(destination);
            if (queue == null) {
                queue = messageBuffer.createMessageQueue();
                queueIndex.put(destination, queue);
                subscriptionIndex.put(destination, queue);
            }
        }
        queue.add(node);
    }

    public List<MessageReference> getMessages(Subscription sub) {
        return getMessages(sub.getConsumerInfo().getDestination());
    }
    
    public  List<MessageReference> getMessages(ActiveMQDestination destination) {
        Set set = null;
        synchronized (lock) {
            set = subscriptionIndex.get(destination);
        }
        List<MessageReference> answer = new ArrayList();
        for (Iterator iter = set.iterator(); iter.hasNext();) {
            MessageQueue queue = (MessageQueue) iter.next();
            queue.appendMessages(answer);
        }
        return answer;
    }
    
    public Message[] browse(ActiveMQDestination destination) {
        List<MessageReference> result = getMessages(destination);
        return result.toArray(new Message[result.size()]);
    }


    public void clear() {
        messageBuffer.clear();
    }
}

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