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Java > Open Source Codes > com > tc > aspectwerkz > cflow > AbstractCflowSystemAspect


1 /*
2  * All content copyright (c) 2003-2006 Terracotta, Inc., except as may otherwise be noted in a separate copyright notice. All rights reserved.
3  */
4 package com.tc.aspectwerkz.cflow;
5
6 import java.util.Stack JavaDoc;
7
8 /**
9  * An abstraction for the JIT gen cflow aspects.
10  * <p/>
11  * A concrete JIT gen cflow aspect *class* will be generated per
12  * cflow sub expression with a consistent naming scheme aka cflowID.
13  * <p/>
14  * The concrete cflow class will extends this one and implements two static methods.
15  * See the sample nested class.
16  * <p/>
17  * Note: the Cflow implements a real aspectOf singleton scheme and is not visible to Aspects.aspectOf
18  *
19  * @author <a HREF="mailto:alex AT gnilux DOT com">Alexandre Vasseur</a>
20  */
21 public abstract class AbstractCflowSystemAspect {
22
23   //TODO do we really need a stack ? I think that an int increment wrapped in a ThreadLocal
24 // will be ok. The stack might only be needed for perCflow deployments
25 public ThreadLocal JavaDoc m_cflowStackLocal = new ThreadLocal JavaDoc() {
26     protected Object JavaDoc initialValue() {
27       return new Stack JavaDoc();
28     }
29   };
30
31   /**
32    * before advice when entering this cflow
33    */
34   public void enter() {
35     ((Stack JavaDoc) m_cflowStackLocal.get()).push(Boolean.TRUE);
36   }
37
38   /**
39    * after finally advice when exiting this cflow
40    */
41   public void exit() {
42     ((Stack JavaDoc) m_cflowStackLocal.get()).pop();
43   }
44
45   /**
46    * @return true if in the cflow
47    */
48   public boolean inCflow() {
49     return ((Stack JavaDoc) m_cflowStackLocal.get()).size() > 0;
50   }
51
52   /**
53    * Sample jit cflow aspect that will gets generated.
54    * Note that we need to test the INSTANCE in case the cflow subexpression
55    * was out of the scope of the weaver (else we gets NullPointerExceptions)
56    *
57    * @author <a HREF="mailto:alex AT gnilux DOT com">Alexandre Vasseur</a>
58    */
59   private static class Cflow_sample extends AbstractCflowSystemAspect {
60
61     private static Cflow_sample INSTANCE = null;
62
63     private Cflow_sample() {
64       super();
65     }
66
67     /**
68      * this method will be invoked by the JIT joinpoint
69      */
70     public static boolean isInCflow() {
71       if (INSTANCE == null) {
72         return false;
73       }
74       return INSTANCE.inCflow();
75     }
76
77     /**
78      * Real aspectOf as a singleton
79      */
80     public static Cflow_sample aspectOf() {
81       if (INSTANCE == null) {
82         INSTANCE = new Cflow_sample();
83       }
84       return INSTANCE;
85     }
86
87   }
88
89 }
90
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