content: /**
   * 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<ActiveMQDestination, MessageQueue>();
      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<MessageReference>();
          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();
      }
  }
  