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Java > Open Source Codes > smallsql > database > TableStorePage


1 /* =============================================================
2  * SmallSQL : a free Java DBMS library for the Java(tm) platform
3  * =============================================================
4  *
5  * (C) Copyright 2004-2006, by Volker Berlin.
6  *
7  * Project Info: http://www.smallsql.de/
8  *
9  * This library is free software; you can redistribute it and/or modify it
10  * under the terms of the GNU Lesser General Public License as published by
11  * the Free Software Foundation; either version 2.1 of the License, or
12  * (at your option) any later version.
13  *
14  * This library is distributed in the hope that it will be useful, but
15  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
16  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
17  * License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with this library; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
22  * USA.
23  *
24  * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
25  * in the United States and other countries.]
26  *
27  * ---------------
28  * TableStorePage.java
29  * ---------------
30  * Author: Volker Berlin
31  *
32  */
33 package smallsql.database;
34
35 import java.sql.*;
36
37 public class TableStorePage extends StorePage{
38     final Table table;
39     
40     // ======= variables needed for locking ========
41 int lockType;
42     SSConnection con;
43     TableStorePage nextLock;
44
45
46     TableStorePage(SSConnection con, Table table, int lockType, long fileOffset){
47         super( null, 0, table.raFile, fileOffset );
48         this.con = con;
49         this.table = table;
50         this.lockType = lockType;
51     }
52        
53     
54     byte[] getData(){
55         return page;
56     }
57     
58     
59     // liefert die finale Position der Page zurück
60 long commit() throws SQLException{
61         if(nextLock != null){
62             // save only the last version of this page
63 fileOffset = nextLock.commit();
64             nextLock = null;
65             rollback();
66             return fileOffset;
67         }
68         if(lockType == TableView.LOCK_READ)
69             return fileOffset;
70         return super.commit();
71     }
72
73     
74     final void freeLock(){
75         table.freeLock(this);
76     }
77 }
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