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comparison src/org/dancres/blitz/notify/QueueEvent.java @ 0:3dc0c5604566

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Initial checkin of blitz 2.0 fcs - no installer yet.
author Dan Creswell <dan.creswell@gmail.com>
date Sat, 21 Mar 2009 11:00:06 +0000
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1 package org.dancres.blitz.notify;
2
3 import org.dancres.blitz.txn.TxnState;
4 import org.dancres.blitz.mangler.MangledEntry;
5 import org.dancres.blitz.oid.OID;
6
7 /**
8 <p>The event types break down into two classes - those that represent
9 an invisible/visible transition and those that represent an
10 unavailable/available transition. Here's a summary in table form:</p>
11
12 <table summary="Visibility and Availability Transitions" border="0" cellspacing="2" cellpadding="1">
13 <tr align="center" valign="middle"><th></th><th>Invisible/Visible</th><th>Unavailable/Available</th>
14 </tr>
15 <tr align="center" valign="middle"><th>ENTRY_WRITE</th>
16 <td>X</td>
17 <td>X</td>
18 </tr>
19 <tr align="center" valign="middle"><th>ENTRY_WRITTEN</th>
20 <td>X</td>
21 <td>X</td>
22 </tr>
23 <tr align="center" valign="middle"><th>ENTRY_VISIBLE</th>
24 <td>X</td>
25 <td>X</td>
26 </tr>
27 <tr align="center" valign="middle"><th>ENTRY_NOT_CONFLICTED</th>
28 <td>O</td>
29 <td>X</td>
30 </tr>
31 </table>
32
33 @see org.dancres.blitz.notify.EventQueue
34 */
35 public class QueueEvent {
36 /**
37 Context object is null
38 */
39 public static final int TRANSACTION_ENDED = 1;
40
41 /**
42 Context object is a MangledEntry plus OID -
43 this event is triggered when a transaction initially writes a new Entry
44 */
45 public static final int ENTRY_WRITE = 2;
46
47 /**
48 Context object is a MangledEntry plus OID -
49 this event is triggered when a transaction commits a write.
50 */
51 public static final int ENTRY_WRITTEN = 3;
52
53 /**
54 Context object is a MangledEntry plus OID - this event is triggered in
55 the case where a take has been aborted and thus an Entry has been deemed
56 visible again.
57 */
58 public static final int ENTRY_VISIBLE = 4;
59
60 /**
61 Context object is a MangledEntry plus OID - this event is triggered in
62 the case where an Entry was previously conflicted with a collection of
63 read locks and has since been made available for a take again.
64 Note, if the Entry was write locked, we don't generate this event
65 as it'll result from the ENTRY_WRITTEN event. Note also we don't
66 generate this event if the Entry is marked as taken/deleted (obviously)
67 */
68 public static final int ENTRY_NOT_CONFLICTED = 5;
69
70 private int theType;
71 private TxnState theTxn;
72 private Context theContext;
73
74 public QueueEvent(int aType, TxnState aTxn, Context aContext) {
75 theType = aType;
76 theTxn = aTxn;
77 theContext = aContext;
78 }
79
80 public int getType() {
81 return theType;
82 }
83
84 public TxnState getTxn() {
85 return theTxn;
86 }
87
88 public Context getContext() {
89 return theContext;
90 }
91
92 public static class Context {
93 private MangledEntry _entry;
94 private OID _oid;
95
96 public Context(MangledEntry anEntry, OID anOID) {
97 _oid = anOID;
98 _entry = anEntry;
99 }
100
101 public MangledEntry getEntry() {
102 return _entry;
103 }
104
105 public OID getOID() {
106 return _oid;
107 }
108 }
109 }