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Java > Open Source Codes > org > jboss > aspects > tx > TransactionLocalAspect


1 /*
2   * JBoss, Home of Professional Open Source
3   * Copyright 2005, JBoss Inc., and individual contributors as indicated
4   * by the @authors tag. See the copyright.txt in the distribution for a
5   * full listing of individual contributors.
6   *
7   * This is free software; you can redistribute it and/or modify it
8   * under the terms of the GNU Lesser General Public License as
9   * published by the Free Software Foundation; either version 2.1 of
10   * the License, or (at your option) any later version.
11   *
12   * This software is distributed in the hope that it will be useful,
13   * but WITHOUT ANY WARRANTY; without even the implied warranty of
14   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15   * Lesser General Public License for more details.
16   *
17   * You should have received a copy of the GNU Lesser General Public
18   * License along with this software; if not, write to the Free
19   * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
20   * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
21   */
22 package org.jboss.aspects.tx;
23
24 import org.jboss.aop.joinpoint.FieldReadInvocation;
25 import org.jboss.aop.joinpoint.FieldWriteInvocation;
26 import org.jboss.tm.TransactionLocal;
27
28 /**
29  * This aspect should be scoped PER_JOINPOINT
30  * It allows a field to have the value of itself pertain
31  * to the current transaction.
32  *
33  * The fields transactional and non-transactional value is always separate
34  * At tx commit, the transactional value the field had is wiped away.
35  * At tx commit, the transactional value does not correspond to the non-transactional value
36  *
37  * If you are within a transaction and you get the value of the field before setting it
38  * then the initial transational value will be set to the current non-transactional value
39  *
40  * @author <a HREF="mailto:bill@jboss.org">Bill Burke</a>
41  * @version $Revision: 37406 $
42  */
43 public class TransactionLocalAspect
44 {
45    private TransactionLocal txLocal = new TransactionLocal();
46
47    public Object JavaDoc access(FieldReadInvocation invocation) throws Throwable JavaDoc
48    {
49       // Return non-Tx value
50 if (txLocal.getTransaction() == null) return invocation.invokeNext();
51
52       // just in case we have a primitive, we can't return null so set txLocal to be the current nonTx value
53 if (txLocal.get() == null)
54       {
55          txLocal.set(invocation.invokeNext());
56       }
57       return txLocal.get();
58    }
59
60    public Object JavaDoc access(FieldWriteInvocation invocation) throws Throwable JavaDoc
61    {
62       // Return non-Tx value
63 if (txLocal.getTransaction() == null) return invocation.invokeNext();
64
65       txLocal.set(invocation.getValue());
66       return null;
67    }
68 }
69
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