LastImageSubscriptionRecoveryPolicy


1   /**
2    *
3    * Licensed to the Apache Software Foundation (ASF) under one or more
4    * contributor license agreements.  See the NOTICE file distributed with
5    * this work for additional information regarding copyright ownership.
6    * The ASF licenses this file to You under the Apache License, Version 2.0
7    * (the "License"); you may not use this file except in compliance with
8    * the License.  You may obtain a copy of the License at
9    *
10   * http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  package org.apache.activemq.broker.region.policy;
19  
20  import java.util.ArrayList  ;
21  import java.util.List  ;
22  import org.apache.activemq.broker.ConnectionContext;
23  import org.apache.activemq.broker.region.MessageReference;
24  import org.apache.activemq.broker.region.SubscriptionRecovery;
25  import org.apache.activemq.broker.region.Topic;
26  import org.apache.activemq.command.ActiveMQDestination;
27  import org.apache.activemq.command.Message;
28  import org.apache.activemq.filter.DestinationFilter;
29  
30  /**
31   * This implementation of {@link SubscriptionRecoveryPolicy} will only keep 
32   * the last message.
33   * 
34   * @org.apache.xbean.XBean
35   * 
36   * @version $Revision$
37   */
38  public class LastImageSubscriptionRecoveryPolicy implements SubscriptionRecoveryPolicy {
39  
40      volatile private MessageReference lastImage;
41  
42      public boolean add(ConnectionContext context, MessageReference node) throws Exception   {
43          lastImage = node;
44          return true;
45      }
46  
47      public void recover(ConnectionContext context,Topic topic,SubscriptionRecovery sub) throws Exception  {
48          // Re-dispatch the last message seen.
49          MessageReference node=lastImage;
50          if(node!=null){
51              sub.addRecoveredMessage(context,node);
52          }
53      }
54  
55      public void start() throws Exception   {
56      }
57  
58      public void stop() throws Exception   {
59      }
60  
61      public Message[] browse(ActiveMQDestination destination) throws Exception  {
62          List   result = new ArrayList  ();
63          DestinationFilter filter=DestinationFilter.parseFilter(destination);
64          if (filter.matches(lastImage.getMessage().getDestination())){
65              result.add(lastImage.getMessage());
66          }
67          return (Message[])result.toArray(new Message[result.size()]);
68      }
69  
70      public SubscriptionRecoveryPolicy copy() {
71          return new LastImageSubscriptionRecoveryPolicy();
72      }
73  
74  }
75
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