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Java > Open Source Codes > com > db4o > YapFieldVersion


1 /* Copyright (C) 2004 - 2006 db4objects Inc. http://www.db4o.com
2
3 This file is part of the db4o open source object database.
4
5 db4o is free software; you can redistribute it and/or modify it under
6 the terms of version 2 of the GNU General Public License as published
7 by the Free Software Foundation and as clarified by db4objects' GPL
8 interpretation policy, available at
9 http://www.db4o.com/about/company/legalpolicies/gplinterpretation/
10 Alternatively you can write to db4objects, Inc., 1900 S Norfolk Street,
11 Suite 350, San Mateo, CA 94403, USA.
12
13 db4o is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
17
18 You should have received a copy of the GNU General Public License along
19 with this program; if not, write to the Free Software Foundation, Inc.,
20 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
21 package com.db4o;
22
23 import com.db4o.ext.*;
24 import com.db4o.inside.marshall.*;
25 import com.db4o.inside.slots.*;
26
27 /**
28  *
29  */
30 class YapFieldVersion extends YapFieldVirtual {
31
32     YapFieldVersion(YapStream stream) {
33         super();
34         i_name = VirtualField.VERSION;
35         i_handler = new YLong(stream);
36     }
37     
38     public void addFieldIndex(MarshallerFamily mf, YapClass yapClass, YapWriter writer, Slot oldSlot) {
39         writer.writeLong(writer.getStream().generateTimeStampId());
40     }
41     
42     public void delete(MarshallerFamily mf, YapWriter a_bytes, boolean isUpdate) {
43         a_bytes.incrementOffset(linkLength());
44     }
45
46     void instantiate1(Transaction a_trans, YapObject a_yapObject, YapReader a_bytes) {
47         a_yapObject.virtualAttributes().i_version = a_bytes.readLong();
48     }
49
50     void marshall1(YapObject a_yapObject, YapWriter a_bytes, boolean a_migrating, boolean a_new) {
51         YapStream stream = a_bytes.getStream().i_parent;
52         VirtualAttributes va = a_yapObject.virtualAttributes();
53         if (! a_migrating) {
54             va.i_version = stream.generateTimeStampId();
55         }
56         if(va == null){
57             a_bytes.writeLong(0);
58         }else{
59             a_bytes.writeLong(va.i_version);
60         }
61     }
62
63     public int linkLength() {
64         return YapConst.LONG_LENGTH;
65     }
66     
67     void marshallIgnore(YapReader writer) {
68         writer.writeLong(0);
69     }
70
71
72 }
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