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: LogicalRowIdManager.java,v 1.3 2005/06/25 23:12:32 doomdark Exp $
46 */
47
48 package jdbm.recman;
49
50 import java.io.IOException;
51
52 /**
53 * This class manages the linked lists of logical rowid pages.
54 */
55 final class LogicalRowIdManager {
56 // our record file and associated page manager
57 private RecordFile file;
58 private PageManager pageman;
59 private FreeLogicalRowIdPageManager freeman;
60
61 /**
62 * Creates a log rowid manager using the indicated record file and
63 * page manager
64 */
65 LogicalRowIdManager(RecordFile file, PageManager pageman)
66 throws IOException {
67 this.file = file;
68 this.pageman = pageman;
69 this.freeman = new FreeLogicalRowIdPageManager(file, pageman);
70
71 }
72
73 /**
74 * Creates a new logical rowid pointing to the indicated physical
75 * id
76 */
77 Location insert(Location loc)
78 throws IOException {
79 // check whether there's a free rowid to reuse
80 Location retval = freeman.get();
81 if (retval == null) {
82 // no. This means that we bootstrap things by allocating
83 // a new translation page and freeing all the rowids on it.
84 long firstPage = pageman.allocate(Magic.TRANSLATION_PAGE);
85 short curOffset = TranslationPage.O_TRANS;
86 for (int i = 0; i < TranslationPage.ELEMS_PER_PAGE; i++) {
87 freeman.put(new Location(firstPage, curOffset));
88 curOffset += PhysicalRowId.SIZE;
89 }
90 retval = freeman.get();
91 if (retval == null) {
92 throw new Error("couldn't obtain free translation");
93 }
94 }
95 // write the translation.
96 update(retval, loc);
97 return retval;
98 }
99
100 /**
101 * Releases the indicated logical rowid.
102 */
103 void delete(Location rowid)
104 throws IOException {
105
106 freeman.put(rowid);
107 }
108
109 /**
110 * Updates the mapping
111 *
112 * @param rowid The logical rowid
113 * @param loc The physical rowid
114 */
115 void update(Location rowid, Location loc)
116 throws IOException {
117
118 TranslationPage xlatPage = TranslationPage.getTranslationPageView(
119 file.get(rowid.getBlock()));
120 PhysicalRowId physid = xlatPage.get(rowid.getOffset());
121 physid.setBlock(loc.getBlock());
122 physid.setOffset(loc.getOffset());
123 file.release(rowid.getBlock(), true);
124 }
125
126 /**
127 * Returns a mapping
128 *
129 * @param rowid The logical rowid
130 * @return The physical rowid
131 */
132 Location fetch(Location rowid)
133 throws IOException {
134
135 TranslationPage xlatPage = TranslationPage.getTranslationPageView(
136 file.get(rowid.getBlock()));
137 try {
138 Location retval = new Location(xlatPage.get(rowid.getOffset()));
139 return retval;
140 } finally {
141 file.release(rowid.getBlock(), false);
142 }
143 }
144
145 }