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1   /*
2    * $Id: TransactedPollingMessageReceiver.java 22656 2011-08-12 07:36:00Z mike.schilling $
3    * --------------------------------------------------------------------------------------
4    * Copyright (c) MuleSoft, Inc.  All rights reserved.  http://www.mulesoft.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.transport;
12  
13  import org.mule.api.MessagingException;
14  import org.mule.api.MuleEvent;
15  import org.mule.api.MuleException;
16  import org.mule.api.MuleMessage;
17  import org.mule.api.config.ThreadingProfile;
18  import org.mule.api.construct.FlowConstruct;
19  import org.mule.api.endpoint.InboundEndpoint;
20  import org.mule.api.lifecycle.CreateException;
21  import org.mule.api.transaction.TransactionCallback;
22  import org.mule.api.transport.Connector;
23  import org.mule.transaction.TransactionTemplate;
24  
25  import java.util.List;
26  import java.util.concurrent.CountDownLatch;
27  
28  import javax.resource.spi.work.Work;
29  
30  /**
31   * The TransactedPollingMessageReceiver is an abstract receiver that handles polling
32   * and transaction management. Derived implementations of these class must be thread
33   * safe as several threads can be started at once for an improved throughput.
34   */
35  public abstract class TransactedPollingMessageReceiver extends AbstractPollingMessageReceiver
36  {
37      /** determines whether messages will be received in a transaction template */
38      private boolean receiveMessagesInTransaction = true;
39  
40      /** determines whether Multiple receivers are created to improve throughput */
41      private boolean useMultipleReceivers = true;
42  
43      public TransactedPollingMessageReceiver(Connector connector,
44                                              FlowConstruct flowConstruct,
45                                              final InboundEndpoint endpoint) throws CreateException
46      {
47          super(connector, flowConstruct, endpoint);
48          this.setReceiveMessagesInTransaction(endpoint.getTransactionConfig().isTransacted());
49      }
50  
51      /**
52       * @deprecated please use
53       *             {@link #TransactedPollingMessageReceiver(Connector, FlowConstruct, InboundEndpoint)}
54       *             instead
55       */
56      @Deprecated
57      public TransactedPollingMessageReceiver(Connector connector,
58                                              FlowConstruct flowConstruct,
59                                              final InboundEndpoint endpoint,
60                                              long frequency) throws CreateException
61      {
62          this(connector, flowConstruct, endpoint);
63          this.setFrequency(frequency);
64      }
65  
66      public boolean isReceiveMessagesInTransaction()
67      {
68          return receiveMessagesInTransaction;
69      }
70  
71      public void setReceiveMessagesInTransaction(boolean useTx)
72      {
73          receiveMessagesInTransaction = useTx;
74      }
75  
76      public boolean isUseMultipleTransactedReceivers()
77      {
78          return useMultipleReceivers;
79      }
80  
81      public void setUseMultipleTransactedReceivers(boolean useMultiple)
82      {
83          useMultipleReceivers = useMultiple;
84      }
85  
86      @Override
87      public void doStart() throws MuleException
88      {
89          // Connector property overrides any implied value
90          this.setUseMultipleTransactedReceivers(connector.isCreateMultipleTransactedReceivers());
91  
92          ThreadingProfile tp = connector.getReceiverThreadingProfile();
93          int numReceiversToStart = 1;
94  
95          if (this.isReceiveMessagesInTransaction() && this.isUseMultipleTransactedReceivers()
96                  && tp.isDoThreading())
97          {
98              numReceiversToStart = connector.getNumberOfConcurrentTransactedReceivers();
99          }
100 
101         for (int i = 0; i < numReceiversToStart; i++)
102         {
103             super.doStart();
104         }
105     }
106 
107     @Override
108     public void poll() throws Exception
109     {
110         TransactionTemplate<Object> tt = new TransactionTemplate<Object>(endpoint.getTransactionConfig(), connector.getMuleContext());
111 
112         if (this.isReceiveMessagesInTransaction())
113         {
114             if (hasNoMessages())
115             {
116                 return;
117             }
118             // Receive messages and process them in a single transaction
119             // Do not enable threading here, but several workers
120             // may have been started
121             TransactionCallback<Object> cb = new TransactionCallback<Object>()
122             {
123                 @Override
124                 public Object doInTransaction() throws Exception
125                 {
126                     // this is not ideal, but jdbc receiver returns a list of maps, not List<MuleMessage>
127                     List messages = getMessages();
128                     if (messages != null && messages.size() > 0)
129                     {
130                         for (Object message : messages)
131                         {
132                             processMessage(message);
133                         }
134                     }
135                     return null;
136                 }
137             };
138             tt.execute(cb);
139         }
140         else
141         {
142             // Receive messages and launch a worker for each message
143             List messages = getMessages();
144             if (messages != null && messages.size() > 0)
145             {
146                 final CountDownLatch countdown = new CountDownLatch(messages.size());
147                 for (Object message : messages)
148                 {
149                     try
150                     {
151                         this.getWorkManager().scheduleWork(
152                                 new MessageProcessorWorker(tt, countdown, message));
153                     }
154                     catch (Exception e)
155                     {
156                         countdown.countDown();
157                         throw e;
158                     }
159                 }
160                 countdown.await();
161             }
162         }
163     }
164 
165     /**
166      * Return true if it can be determined that there are currently no messages to process
167      */
168     protected boolean hasNoMessages()
169     {
170         return  false;
171     }
172 
173     protected class MessageProcessorWorker implements Work, TransactionCallback
174     {
175         private final TransactionTemplate tt;
176         private final Object message;
177         private final CountDownLatch latch;
178 
179         public MessageProcessorWorker(TransactionTemplate tt, CountDownLatch latch, Object message)
180         {
181             this.tt = tt;
182             this.message = message;
183             this.latch = latch;
184         }
185 
186         @Override
187         public void release()
188         {
189             // nothing to do
190         }
191 
192         @Override
193         public void run()
194         {
195             try
196             {
197                 tt.execute(this);
198             }
199             catch (MessagingException e)
200             {
201                 MuleEvent event = e.getEvent();
202                 event.getFlowConstruct().getExceptionListener().handleException(e, event);
203             }
204             catch (Exception e)
205             {
206                 connector.getMuleContext().getExceptionListener().handleException(e);
207             }
208             finally
209             {
210                 latch.countDown();
211             }
212         }
213 
214         @Override
215         public Object doInTransaction() throws Exception
216         {
217             processMessage(message);
218             return null;
219         }
220 
221     }
222 
223     protected abstract List<MuleMessage> getMessages() throws Exception;
224 
225     protected abstract void processMessage(Object message) throws Exception;
226 
227 }