001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.activemq.memory.list;
018    
019    import java.util.ArrayList;
020    import java.util.HashMap;
021    import java.util.Iterator;
022    import java.util.List;
023    import java.util.Map;
024    import java.util.Set;
025    import org.apache.activemq.broker.region.MessageReference;
026    import org.apache.activemq.broker.region.Subscription;
027    import org.apache.activemq.command.ActiveMQDestination;
028    import org.apache.activemq.command.ActiveMQMessage;
029    import org.apache.activemq.command.Message;
030    import org.apache.activemq.filter.DestinationMap;
031    import org.apache.activemq.memory.buffer.MessageBuffer;
032    import org.apache.activemq.memory.buffer.MessageQueue;
033    import org.apache.activemq.memory.buffer.OrderBasedMessageBuffer;
034    
035    /**
036     * An implementation of {@link MessageList} which maintains a separate message
037     * list for each destination to reduce contention on the list and to speed up
038     * recovery times by only recovering the interested topics.
039     * 
040     * 
041     */
042    public class DestinationBasedMessageList implements MessageList {
043    
044        private MessageBuffer messageBuffer;
045        private Map<ActiveMQDestination, MessageQueue> queueIndex = new HashMap<ActiveMQDestination, MessageQueue>();
046        private DestinationMap subscriptionIndex = new DestinationMap();
047        private Object lock = new Object();
048    
049        public DestinationBasedMessageList(int maximumSize) {
050            this(new OrderBasedMessageBuffer(maximumSize));
051        }
052        
053        public DestinationBasedMessageList(MessageBuffer buffer) {
054            messageBuffer = buffer;
055        }
056    
057        public void add(MessageReference node) {
058            ActiveMQMessage message = (ActiveMQMessage) node.getMessageHardRef();
059            ActiveMQDestination destination = message.getDestination();
060            MessageQueue queue = null;
061            synchronized (lock) {
062                queue = queueIndex.get(destination);
063                if (queue == null) {
064                    queue = messageBuffer.createMessageQueue();
065                    queueIndex.put(destination, queue);
066                    subscriptionIndex.put(destination, queue);
067                }
068            }
069            queue.add(node);
070        }
071    
072        public List<MessageReference> getMessages(Subscription sub) {
073            return getMessages(sub.getConsumerInfo().getDestination());
074        }
075        
076        public  List<MessageReference> getMessages(ActiveMQDestination destination) {
077            Set set = null;
078            synchronized (lock) {
079                set = subscriptionIndex.get(destination);
080            }
081            List<MessageReference> answer = new ArrayList<MessageReference>();
082            for (Iterator iter = set.iterator(); iter.hasNext();) {
083                MessageQueue queue = (MessageQueue) iter.next();
084                queue.appendMessages(answer);
085            }
086            return answer;
087        }
088        
089        public Message[] browse(ActiveMQDestination destination) {
090            List<MessageReference> result = getMessages(destination);
091            return result.toArray(new Message[result.size()]);
092        }
093    
094    
095        public void clear() {
096            messageBuffer.clear();
097        }
098    }