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1   /*
2    * $Id: IdempotentReceiver.java 7976 2007-08-21 14:26:13Z dirk.olmes $
3    * --------------------------------------------------------------------------------------
4    * Copyright (c) MuleSource, Inc.  All rights reserved.  http://www.mulesource.com
5    *
6    * The software in this package is published under the terms of the CPAL v1.0
7    * license, a copy of which has been included with this distribution in the
8    * LICENSE.txt file.
9    */
10  
11  package org.mule.routing.inbound;
12  
13  import org.mule.MuleManager;
14  import org.mule.config.i18n.CoreMessages;
15  import org.mule.umo.MessagingException;
16  import org.mule.umo.UMOEvent;
17  import org.mule.umo.routing.RoutingException;
18  import org.mule.util.FileUtils;
19  
20  import java.io.BufferedReader;
21  import java.io.File;
22  import java.io.FileReader;
23  import java.io.IOException;
24  import java.util.HashSet;
25  import java.util.Set;
26  
27  /**
28   * <code>IdempotentReceiver</code> ensures that only unique messages are received
29   * by a component. It does this by checking the unique id of the incoming message.
30   * Note that the underlying endpoint must support unique message Ids for this to
31   * work, otherwise a <code>UniqueIdNotSupportedException</code> is thrown. This
32   * implementation is simple and not suitable in a failover environment, this is
33   * because previously received message Ids are stored in memory and not persisted.
34   * 
35   */
36  //TODO MULE-1300: fix memory leak
37  public class IdempotentReceiver extends SelectiveConsumer
38  {
39      private static final String DEFAULT_STORE_PATH = "./idempotent";
40  
41      private Set messageIds;
42      private File idStore;
43      private String componentName;
44      private boolean disablePersistence = false;
45      private String storePath;
46  
47      public IdempotentReceiver()
48      {
49          messageIds = new HashSet();
50          String path = MuleManager.getConfiguration().getWorkingDirectory() + "/idempotent";
51          setStorePath(path);
52      }
53  
54      // @Override
55      public boolean isMatch(UMOEvent event) throws MessagingException
56      {
57          if (idStore == null)
58          {
59              // we need to load this of fist request as we need the component
60              // name
61              this.load(event);
62          }
63          return !messageIds.contains(this.getIdForEvent(event));
64      }
65  
66      // @Override
67      public UMOEvent[] process(UMOEvent event) throws MessagingException
68      {
69          if (isMatch(event))
70          {
71              try
72              {
73                  checkComponentName(event.getComponent().getDescriptor().getName());
74              }
75              catch (IllegalArgumentException e)
76              {
77                  throw new RoutingException(event.getMessage(), event.getEndpoint(), e);
78              }
79  
80              Object id = this.getIdForEvent(event);
81              try
82              {
83                  this.storeId(id);
84                  return new UMOEvent[]{event};
85              }
86              catch (IOException e)
87              {
88                  throw new RoutingException(
89                      CoreMessages.failedToWriteMessageToStore(id, idStore.getAbsolutePath()),
90                      event.getMessage(), event.getEndpoint(), e);
91              }
92          }
93          else
94          {
95              return null;
96          }
97      }
98  
99      protected Object getIdForEvent(UMOEvent event) throws MessagingException
100     {
101         return event.getMessage().getUniqueId();
102     }
103 
104     private void checkComponentName(String name) throws IllegalArgumentException
105     {
106         if (!componentName.equals(name))
107         {
108             throw new IllegalArgumentException("This receiver is assigned to component: " + componentName
109                                                + " but has received an event for component: " + name
110                                                + ". Please check your config to make sure each component"
111                                                + "has its own instance of IdempotentReceiver");
112         }
113     }
114 
115     protected synchronized void load(UMOEvent event) throws RoutingException
116     {
117         this.componentName = event.getComponent().getDescriptor().getName();
118         
119         if (idStore == null)
120         {
121             idStore = FileUtils.newFile(storePath + "/muleComponent_" + componentName + ".store");
122         }
123 
124         if (disablePersistence)
125         {
126             return;
127         }
128 
129         try
130         {
131             if (idStore.exists())
132             {
133                 BufferedReader reader = null;
134                 try
135                 {
136                     reader = new BufferedReader(new FileReader(idStore));
137                     String id;
138                     while ((id = reader.readLine()) != null)
139                     {
140                         messageIds.add(id);
141                     }
142                 }
143                 finally
144                 {
145                     if (reader != null)
146                     {
147                         reader.close();
148                     }
149                 }
150             }
151             else
152             {
153                 idStore = FileUtils.createFile(idStore.getAbsolutePath());
154             }
155         }
156         catch (IOException e)
157         {
158             throw new RoutingException(
159                 CoreMessages.failedToReadFromStore(idStore.getAbsolutePath()),
160                 event.getMessage(), event.getEndpoint(), e);
161         }
162     }
163 
164     protected synchronized void storeId(Object id) throws IOException
165     {
166         messageIds.add(id);
167         if (disablePersistence)
168         {
169             return;
170         }
171         FileUtils.stringToFile(idStore.getAbsolutePath(), id.toString(), true, true);
172     }
173 
174     public boolean isDisablePersistence()
175     {
176         return disablePersistence;
177     }
178 
179     public void setDisablePersistence(boolean disablePersistence)
180     {
181         this.disablePersistence = disablePersistence;
182     }
183 
184     public String getStorePath()
185     {
186         return storePath;
187     }
188 
189     public void setStorePath(String storePath)
190     {
191         if (storePath == null)
192         {
193             this.storePath = DEFAULT_STORE_PATH;
194         }
195         else if (storePath.endsWith("/"))
196         {
197             storePath = storePath.substring(0, storePath.length() - 1);
198             this.storePath = storePath;
199         }
200         else
201         {
202             this.storePath = storePath;
203         }
204     }
205 
206 }