1 /**
2 * JDBM LICENSE v1.00
3 *
4 * Redistribution and use of this software and associated documentation
5 * ("Software"), with or without modification, are permitted provided
6 * that the following conditions are met:
7 *
8 * 1. Redistributions of source code must retain copyright
9 * statements and notices. Redistributions must also contain a
10 * copy of this document.
11 *
12 * 2. Redistributions in binary form must reproduce the
13 * above copyright notice, this list of conditions and the
14 * following disclaimer in the documentation and/or other
15 * materials provided with the distribution.
16 *
17 * 3. The name "JDBM" must not be used to endorse or promote
18 * products derived from this Software without prior written
19 * permission of Cees de Groot. For written permission,
20 * please contact cg@cdegroot.com.
21 *
22 * 4. Products derived from this Software may not be called "JDBM"
23 * nor may "JDBM" appear in their names without prior written
24 * permission of Cees de Groot.
25 *
26 * 5. Due credit should be given to the JDBM Project
27 * (http://jdbm.sourceforge.net/).
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE JDBM PROJECT AND CONTRIBUTORS
30 * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
31 * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
32 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
33 * CEES DE GROOT OR ANY CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
34 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
35 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
36 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
38 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
39 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
40 * OF THE POSSIBILITY OF SUCH DAMAGE.
41 *
42 * Copyright 2000 (C) Cees de Groot. All Rights Reserved.
43 * Contributions are Copyright (C) 2000 by their associated contributors.
44 *
45 * $Id: PhysicalRowId.java,v 1.1 2000/05/06 00:00:31 boisvert Exp $
46 */
47
48 package jdbm.recman;
49
50 /**
51 * A physical rowid is nothing else than a pointer to a physical location
52 * in a file - a (block, offset) tuple.
53 * <P>
54 * <B>Note</B>: The fact that the offset is modelled as a short limits
55 * the block size to 32k.
56 */
57 class PhysicalRowId {
58 // offsets
59 private static final short O_BLOCK = 0; // long block
60 private static final short O_OFFSET = Magic.SZ_LONG; // short offset
61 static final int SIZE = O_OFFSET + Magic.SZ_SHORT;
62
63 // my block and the position within the block
64 BlockIo block;
65 short pos;
66
67 /**
68 * Constructs a physical rowid from the indicated data starting at
69 * the indicated position.
70 */
71 PhysicalRowId(BlockIo block, short pos) {
72 this.block = block;
73 this.pos = pos;
74 }
75
76 /** Returns the block number */
77 long getBlock() {
78 return block.readLong(pos + O_BLOCK);
79 }
80
81 /** Sets the block number */
82 void setBlock(long value) {
83 block.writeLong(pos + O_BLOCK, value);
84 }
85
86 /** Returns the offset */
87 short getOffset() {
88 return block.readShort(pos + O_OFFSET);
89 }
90
91 /** Sets the offset */
92 void setOffset(short value) {
93 block.writeShort(pos + O_OFFSET, value);
94 }
95 }