01: /**
02: * JDBM LICENSE v1.00
03: *
04: * Redistribution and use of this software and associated documentation
05: * ("Software"), with or without modification, are permitted provided
06: * that the following conditions are met:
07: *
08: * 1. Redistributions of source code must retain copyright
09: * 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: */package jdbm.recman;
47:
48: /**
49: * A physical rowid is nothing else than a pointer to a physical location
50: * in a file - a (block, offset) tuple.
51: * <P>
52: * <B>Note</B>: The fact that the offset is modelled as a short limits
53: * the block size to 32k.
54: */
55: class PhysicalRowId {
56: // offsets
57: private static final short O_BLOCK = 0; // long block
58: private static final short O_OFFSET = Magic.SZ_LONG; // short offset
59: static final int SIZE = O_OFFSET + Magic.SZ_SHORT;
60:
61: // my block and the position within the block
62: BlockIo block;
63: short pos;
64:
65: /**
66: * Constructs a physical rowid from the indicated data starting at
67: * the indicated position.
68: */
69: PhysicalRowId(BlockIo block, short pos) {
70: this .block = block;
71: this .pos = pos;
72: }
73:
74: /** Returns the block number */
75: long getBlock() {
76: return block.readLong(pos + O_BLOCK);
77: }
78:
79: /** Sets the block number */
80: void setBlock(long value) {
81: block.writeLong(pos + O_BLOCK, value);
82: }
83:
84: /** Returns the offset */
85: short getOffset() {
86: return block.readShort(pos + O_OFFSET);
87: }
88:
89: /** Sets the offset */
90: void setOffset(short value) {
91: block.writeShort(pos + O_OFFSET, value);
92: }
93: }
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