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1   /*
2    * $Id: TransactedPollingMessageReceiver.java 19191 2010-08-25 21:05:23Z tcarlson $
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.MuleException;
14  import org.mule.api.MuleMessage;
15  import org.mule.api.config.ThreadingProfile;
16  import org.mule.api.construct.FlowConstruct;
17  import org.mule.api.endpoint.InboundEndpoint;
18  import org.mule.api.lifecycle.CreateException;
19  import org.mule.api.transaction.TransactionCallback;
20  import org.mule.api.transport.Connector;
21  import org.mule.transaction.TransactionTemplate;
22  
23  import java.util.List;
24  
25  import javax.resource.spi.work.Work;
26  
27  import edu.emory.mathcs.backport.java.util.concurrent.CountDownLatch;
28  
29  /**
30   * The TransactedPollingMessageReceiver is an abstract receiver that handles polling
31   * and transaction management. Derived implementations of these class must be thread
32   * safe as several threads can be started at once for an improved throughput.
33   */
34  public abstract class TransactedPollingMessageReceiver extends AbstractPollingMessageReceiver
35  {
36      /** determines whether messages will be received in a transaction template */
37      private boolean receiveMessagesInTransaction = true;
38  
39      /** determines whether Multiple receivers are created to improve throughput */
40      private boolean useMultipleReceivers = true;
41  
42      public TransactedPollingMessageReceiver(Connector connector,
43                                              FlowConstruct flowConstruct,
44                                              final InboundEndpoint endpoint) throws CreateException
45      {
46          super(connector, flowConstruct, endpoint);
47          this.setReceiveMessagesInTransaction(endpoint.getTransactionConfig().isTransacted());
48      }
49  
50      /**
51       * @deprecated please use
52       *             {@link #TransactedPollingMessageReceiver(Connector, FlowConstruct, InboundEndpoint)}
53       *             instead
54       */
55      @Deprecated
56      public TransactedPollingMessageReceiver(Connector connector,
57                                              FlowConstruct flowConstruct,
58                                              final InboundEndpoint endpoint,
59                                              long frequency) throws CreateException
60      {
61          this(connector, flowConstruct, endpoint);
62          this.setFrequency(frequency);
63      }
64  
65      public boolean isReceiveMessagesInTransaction()
66      {
67          return receiveMessagesInTransaction;
68      }
69  
70      public void setReceiveMessagesInTransaction(boolean useTx)
71      {
72          receiveMessagesInTransaction = useTx;
73      }
74  
75      public boolean isUseMultipleTransactedReceivers()
76      {
77          return useMultipleReceivers;
78      }
79  
80      public void setUseMultipleTransactedReceivers(boolean useMultiple)
81      {
82          useMultipleReceivers = useMultiple;
83      }
84  
85      @Override
86      public void doStart() throws MuleException
87      {
88          // Connector property overrides any implied value
89          this.setUseMultipleTransactedReceivers(connector.isCreateMultipleTransactedReceivers());
90  
91          ThreadingProfile tp = connector.getReceiverThreadingProfile();
92          int numReceiversToStart = 1;
93  
94          if (this.isReceiveMessagesInTransaction() && this.isUseMultipleTransactedReceivers()
95                  && tp.isDoThreading())
96          {
97              numReceiversToStart = connector.getNumberOfConcurrentTransactedReceivers();
98          }
99  
100         for (int i = 0; i < numReceiversToStart; i++)
101         {
102             super.doStart();
103         }
104     }
105 
106     @Override
107     public void poll() throws Exception
108     {
109         TransactionTemplate<Object> tt = new TransactionTemplate<Object>(endpoint.getTransactionConfig(), connector.getMuleContext());
110 
111         if (this.isReceiveMessagesInTransaction())
112         {
113             // Receive messages and process them in a single transaction
114             // Do not enable threading here, but several workers
115             // may have been started
116             TransactionCallback<Object> cb = new TransactionCallback<Object>()
117             {
118                 public Object doInTransaction() throws Exception
119                 {
120                     // this is not ideal, but jdbc receiver returns a list of maps, not List<MuleMessage>
121                     List messages = getMessages();
122                     if (messages != null && messages.size() > 0)
123                     {
124                         for (Object message : messages)
125                         {
126                             processMessage(message);
127                         }
128                     }
129                     return null;
130                 }
131             };
132             tt.execute(cb);
133         }
134         else
135         {
136             // Receive messages and launch a worker for each message
137             List messages = getMessages();
138             if (messages != null && messages.size() > 0)
139             {
140                 final CountDownLatch countdown = new CountDownLatch(messages.size());
141                 for (Object message : messages)
142                 {
143                     try
144                     {
145                         this.getWorkManager().scheduleWork(
146                                 new MessageProcessorWorker(tt, countdown, message));
147                     }
148                     catch (Exception e)
149                     {
150                         countdown.countDown();
151                         throw e;
152                     }
153                 }
154                 countdown.await();
155             }
156         }
157     }
158 
159     protected class MessageProcessorWorker implements Work, TransactionCallback
160     {
161         private final TransactionTemplate tt;
162         private final Object message;
163         private final CountDownLatch latch;
164 
165         public MessageProcessorWorker(TransactionTemplate tt, CountDownLatch latch, Object message)
166         {
167             this.tt = tt;
168             this.message = message;
169             this.latch = latch;
170         }
171 
172         public void release()
173         {
174             // nothing to do
175         }
176 
177         public void run()
178         {
179             try
180             {
181                 tt.execute(this);
182             }
183             catch (Exception e)
184             {
185                 connector.getMuleContext().getExceptionListener().handleException(e);
186             }
187             finally
188             {
189                 latch.countDown();
190             }
191         }
192 
193         public Object doInTransaction() throws Exception
194         {
195             processMessage(message);
196             return null;
197         }
198 
199     }
200 
201     protected abstract List<MuleMessage> getMessages() throws Exception;
202 
203     protected abstract void processMessage(Object message) throws Exception;
204 
205 }