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Java > Open Source Codes > org > jacorb > trading > db > pse > util > TransactionMgr


1
2 // Copyright (C) 1998-1999
3 // Object Oriented Concepts, Inc.
4
5 // **********************************************************************
6 //
7 // Copyright (c) 1997
8 // Mark Spruiell (mark@intellisoft.com)
9 //
10 // See the COPYING file for more information
11 //
12 // **********************************************************************
13
14 package org.jacorb.trading.db.pse.util;
15
16 import COM.odi.*;
17
18
19 /**
20  * ObjectStore PSE does not allow nested transactions, nor does it allow
21  * multiple active sessions, so we have to coordinate access to transactions
22  * to prevent multiple threads from entering a transaction.
23  */
24 public class TransactionMgr
25 {
26   private Thread JavaDoc m_mainThread;
27   private Thread JavaDoc m_owner = null;
28   private int m_refCount = 0;
29
30
31   public TransactionMgr()
32   {
33       // remember the main thread
34 m_mainThread = Thread.currentThread();
35   }
36
37
38   public synchronized void begin()
39   {
40       // initialize this thread with the database
41 ObjectStore.initialize(m_mainThread);
42
43     Thread JavaDoc currentThread = Thread.currentThread();
44
45       // allow the same thread to acquire more than once
46 if (currentThread != m_owner) {
47       while (m_refCount != 0) {
48         try {
49           wait();
50         }
51         catch (InterruptedException JavaDoc e) {
52         }
53       }
54     }
55
56       // since we allow the same thread to call begin() more than once,
57 // we don't want to worry about conflicting transaction modes
58 if (m_refCount == 0)
59       Transaction.begin(ObjectStore.UPDATE);
60
61     m_owner = currentThread;
62     m_refCount++;
63   }
64
65
66   public synchronized void commit(int retain)
67   {
68     Thread JavaDoc currentThread = Thread.currentThread();
69     if (currentThread != m_owner)
70       throw new RuntimeException JavaDoc("Thread not owner");
71
72     if (m_refCount > 0)
73       m_refCount--;
74     else if (m_refCount == 0)
75       throw new RuntimeException JavaDoc("refCount should not be 0");
76
77       // commit the transaction if this is the last release()
78 if (m_refCount == 0) {
79       Transaction.current().commit(retain);
80         // disconnect this thread from the database
81 ObjectStore.shutdown(false);
82       m_owner = null;
83       notifyAll();
84     }
85   }
86 }
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