1 /*
2 * Copyright (C) 2011, Google Inc.
3 * and other copyright owners as documented in the project's IP log.
4 *
5 * This program and the accompanying materials are made available
6 * under the terms of the Eclipse Distribution License v1.0 which
7 * accompanies this distribution, is reproduced below, and is
8 * available at http://www.eclipse.org/org/documents/edl-v10.php
9 *
10 * All rights reserved.
11 *
12 * Redistribution and use in source and binary forms, with or
13 * without modification, are permitted provided that the following
14 * conditions are met:
15 *
16 * - Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 *
19 * - Redistributions in binary form must reproduce the above
20 * copyright notice, this list of conditions and the following
21 * disclaimer in the documentation and/or other materials provided
22 * with the distribution.
23 *
24 * - Neither the name of the Eclipse Foundation, Inc. nor the
25 * names of its contributors may be used to endorse or promote
26 * products derived from this software without specific prior
27 * written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
30 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
31 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
32 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
33 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
34 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
35 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
36 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
37 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
38 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
40 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
41 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
42 */
43
44 package org.eclipse.jgit.internal.storage.dfs;
45
46 import static org.eclipse.jgit.lib.Constants.CHARSET;
47
48 import java.util.Arrays;
49
50 import org.eclipse.jgit.annotations.Nullable;
51 import org.eclipse.jgit.internal.storage.pack.PackExt;
52
53 /**
54 * Key used by {@link org.eclipse.jgit.internal.storage.dfs.DfsBlockCache} to disambiguate streams.
55 */
56 public abstract class DfsStreamKey {
57 /**
58 * Create a {@code DfsStreamKey}
59 *
60 * @param repo
61 * description of the containing repository.
62 * @param name
63 * compute the key from a string name.
64 * @param ext
65 * pack file extension, or {@code null}.
66 * @return key for {@code name}
67 */
68 public static DfsStreamKey of(DfsRepositoryDescription repo, String name,
69 @Nullable PackExt ext) {
70 return new ByteArrayDfsStreamKey(repo, name.getBytes(CHARSET), ext);
71 }
72
73 final int hash;
74
75 final int packExtPos;
76
77 /**
78 * Constructor for DfsStreamKey.
79 *
80 * @param hash
81 * hash of the other identifying components of the key.
82 * @param ext
83 * pack file extension, or {@code null}.
84 */
85 protected DfsStreamKey(int hash, @Nullable PackExt ext) {
86 // Multiply by 31 here so we can more directly combine with another
87 // value without doing the multiply there.
88 this.hash = hash * 31;
89 this.packExtPos = ext == null ? 0 : ext.getPosition();
90 }
91
92 /** {@inheritDoc} */
93 @Override
94 public int hashCode() {
95 return hash;
96 }
97
98 /** {@inheritDoc} */
99 @Override
100 public abstract boolean equals(Object o);
101
102 /** {@inheritDoc} */
103 @SuppressWarnings("boxing")
104 @Override
105 public String toString() {
106 return String.format("DfsStreamKey[hash=%08x]", hash); //$NON-NLS-1$
107 }
108
109 private static final class ByteArrayDfsStreamKey extends DfsStreamKey {
110 private final DfsRepositoryDescription repo;
111
112 private final byte[] name;
113
114 ByteArrayDfsStreamKey(DfsRepositoryDescription repo, byte[] name,
115 @Nullable PackExt ext) {
116 super(repo.hashCode() * 31 + Arrays.hashCode(name), ext);
117 this.repo = repo;
118 this.name = name;
119 }
120
121 @Override
122 public boolean equals(Object o) {
123 if (o instanceof ByteArrayDfsStreamKey) {
124 ByteArrayDfsStreamKey k = (ByteArrayDfsStreamKey) o;
125 return hash == k.hash && repo.equals(k.repo)
126 && Arrays.equals(name, k.name);
127 }
128 return false;
129 }
130 }
131
132 static final class ForReverseIndex extends DfsStreamKey {
133 private final DfsStreamKey idxKey;
134
135 ForReverseIndex(DfsStreamKey idxKey) {
136 super(idxKey.hash + 1, null);
137 this.idxKey = idxKey;
138 }
139
140 @Override
141 public boolean equals(Object o) {
142 return o instanceof ForReverseIndex
143 && idxKey.equals(((ForReverseIndex) o).idxKey);
144 }
145 }
146 }