| 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 | * Identity.java |
| 29 | * --------------- |
| 30 | * Author: Volker Berlin |
| 31 | * |
| 32 | * Created on 16.04.2004 |
| 33 | */ |
| 34 | package smallsql.database; |
| 35 | |
| 36 | import java.io.*; |
| 37 | import java.sql.SQLException; |
| 38 | |
| 39 | |
| 40 | /** |
| 41 | * @author Volker Berlin |
| 42 | */ |
| 43 | public class Identity extends Number { |
| 44 | |
| 45 | final private long filePos; |
| 46 | final private RandomAccessFile raFile; |
| 47 | final private byte[] page = new byte[8]; |
| 48 | final private Table table; |
| 49 | private long value; |
| 50 | |
| 51 | public Identity(Table table, RandomAccessFile raFile, long filePos) throws IOException{ |
| 52 | synchronized(raFile){ |
| 53 | raFile.seek(filePos); |
| 54 | raFile.read(page); |
| 55 | } |
| 56 | value = ((long)(page[ 0 ]) << 56) | |
| 57 | ((long)(page[ 1 ] & 0xFF) << 48) | |
| 58 | ((long)(page[ 2 ] & 0xFF) << 40) | |
| 59 | ((long)(page[ 3 ] & 0xFF) << 32) | |
| 60 | ((long)(page[ 4 ] & 0xFF) << 24) | |
| 61 | ((page[ 5 ] & 0xFF) << 16) | |
| 62 | ((page[ 6 ] & 0xFF) << 8) | |
| 63 | ((page[ 7 ] & 0xFF)); |
| 64 | this.table = table; |
| 65 | this.raFile = raFile; |
| 66 | this.filePos = filePos; |
| 67 | } |
| 68 | |
| 69 | private StorePage createStorePage(){ |
| 70 | page[ 0 ] = (byte)(value >> 56); |
| 71 | page[ 1 ] = (byte)(value >> 48); |
| 72 | page[ 2 ] = (byte)(value >> 40); |
| 73 | page[ 3 ] = (byte)(value >> 32); |
| 74 | page[ 4 ] = (byte)(value >> 24); |
| 75 | page[ 5 ] = (byte)(value >> 16); |
| 76 | page[ 6 ] = (byte)(value >> 8); |
| 77 | page[ 7 ] = (byte)(value); |
| 78 | return new StorePage( page, 8, raFile, filePos); |
| 79 | } |
| 80 | |
| 81 | void createNextValue(SSConnection con) throws SQLException{ |
| 82 | value++; |
| 83 | con.add( createStorePage() ); |
| 84 | } |
| 85 | |
| 86 | |
| 87 | void setNextValue(Expression expr) throws Exception{ |
| 88 | if(expr.isNull()) return; |
| 89 | long newValue = expr.getLong(); |
| 90 | if(newValue > value){ |
| 91 | value = newValue; |
| 92 | createStorePage().commit(); |
| 93 | } |
| 94 | } |
| 95 | |
| 96 | public float floatValue() { |
| 97 | return value; |
| 98 | } |
| 99 | |
| 100 | public double doubleValue() { |
| 101 | return value; |
| 102 | } |
| 103 | |
| 104 | public int intValue() { |
| 105 | return (int)value; |
| 106 | } |
| 107 | |
| 108 | public long longValue() { |
| 109 | return value; |
| 110 | } |
| 111 | |
| 112 | } |