1 /*
2 * Copyright (C) 2012, 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.file;
45
46 import com.googlecode.javaewah.EWAHCompressedBitmap;
47
48 import org.eclipse.jgit.lib.AnyObjectId;
49 import org.eclipse.jgit.lib.ObjectIdOwnerMap;
50
51 /**
52 * Base implementation of the PackBitmapIndex.
53 */
54 abstract class BasePackBitmapIndex extends PackBitmapIndex {
55 private final ObjectIdOwnerMap<StoredBitmap> bitmaps;
56
57 BasePackBitmapIndex(ObjectIdOwnerMap<StoredBitmap> bitmaps) {
58 this.bitmaps = bitmaps;
59 }
60
61 public EWAHCompressedBitmap getBitmap(AnyObjectId objectId) {
62 StoredBitmap sb = bitmaps.get(objectId);
63 return sb != null ? sb.getBitmap() : null;
64 }
65
66 ObjectIdOwnerMap<StoredBitmap> getBitmaps() {
67 return bitmaps;
68 }
69
70 /**
71 * Data representation of the bitmap entry restored from a pack index. The
72 * commit of the bitmap is the map key.
73 */
74 static final class StoredBitmap extends ObjectIdOwnerMap.Entry {
75 private volatile Object bitmapContainer;
76 private final int flags;
77
78 StoredBitmap(AnyObjectId objectId, EWAHCompressedBitmap bitmap,
79 StoredBitmap xorBitmap, int flags) {
80 super(objectId);
81 this.bitmapContainer = xorBitmap == null
82 ? bitmap
83 : new XorCompressedBitmap(bitmap, xorBitmap);
84 this.flags = flags;
85 }
86
87 /**
88 * Computes and returns the full bitmap.
89 *
90 * @return the full bitmap
91 */
92 EWAHCompressedBitmap getBitmap() {
93 // Fast path to immediately return the expanded result.
94 Object r = bitmapContainer;
95 if (r instanceof EWAHCompressedBitmap)
96 return (EWAHCompressedBitmap) r;
97
98 // Expand the bitmap and cache the result.
99 XorCompressedBitmap xb = (XorCompressedBitmap) r;
100 EWAHCompressedBitmap out = xb.bitmap;
101 for (;;) {
102 r = xb.xorBitmap.bitmapContainer;
103 if (r instanceof EWAHCompressedBitmap) {
104 out = out.xor((EWAHCompressedBitmap) r);
105 bitmapContainer = out;
106 return out;
107 }
108 xb = (XorCompressedBitmap) r;
109 out = out.xor(xb.bitmap);
110 }
111 }
112
113 /** @return the flags associated with the bitmap */
114 int getFlags() {
115 return flags;
116 }
117 }
118
119 private static final class XorCompressedBitmap {
120 final EWAHCompressedBitmap bitmap;
121 final StoredBitmap xorBitmap;
122
123 XorCompressedBitmap(EWAHCompressedBitmap b, StoredBitmap xb) {
124 bitmap = b;
125 xorBitmap = xb;
126 }
127 }
128 }