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comparison src/org/tmatesoft/hg/internal/Patch.java @ 329:694ebabb5cb3

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Refactor revlog patch mechanism, towards patch merging
author Artem Tikhomirov <tikhomirov.artem@gmail.com>
date Thu, 13 Oct 2011 03:30:50 +0200
parents
children 9747a786a34d
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328:a674b8590362 329:694ebabb5cb3
1 /*
2 * Copyright (c) 2011 TMate Software Ltd
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; version 2 of the License.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * For information on how to redistribute this software under
14 * the terms of a license other than GNU General Public License
15 * contact TMate Software at support@hg4j.com
16 */
17 package org.tmatesoft.hg.internal;
18
19 import java.io.IOException;
20 import java.util.ArrayList;
21
22 /**
23 * @see http://mercurial.selenic.com/wiki/BundleFormat, in Changelog group description
24 *
25 * range [start..end] in original source gets replaced with data of length (do not keep, use data.length instead)
26 * range [end(i)..start(i+1)] is copied from the source
27 *
28 * @author Artem Tikhomirov
29 * @author TMate Software Ltd.
30 */
31 public final class Patch {
32 private final IntVector starts, ends;
33 private final ArrayList<byte[]> data;
34
35 public Patch() {
36 starts = new IntVector();
37 ends = new IntVector();
38 data = new ArrayList<byte[]>();
39 }
40
41 public int count() {
42 return data.size();
43 }
44
45 // number of bytes this patch will add (or remove, if negative) from the base revision
46 private int patchSizeDelta() {
47 int rv = 0;
48 int prevEnd = 0;
49 for (int i = 0, x = data.size(); i < x; i++) {
50 final int start = starts.get(i);
51 final int len = data.get(i).length;
52 rv += start - prevEnd; // would copy from original
53 rv += len; // and add new
54 prevEnd = ends.get(i);
55 }
56 rv -= prevEnd;
57 return rv;
58 }
59
60 public byte[] apply(DataAccess baseRevisionContent, int outcomeLen) throws IOException {
61 if (outcomeLen == -1) {
62 outcomeLen = baseRevisionContent.length() + patchSizeDelta();
63 }
64 int prevEnd = 0, destIndex = 0;
65 byte[] rv = new byte[outcomeLen];
66 for (int i = 0, x = data.size(); i < x; i++) {
67 final int start = starts.get(i);
68 baseRevisionContent.seek(prevEnd);
69 // copy source bytes that were not modified (up to start of the record)
70 baseRevisionContent.readBytes(rv, destIndex, start - prevEnd);
71 destIndex += start - prevEnd;
72 // insert new data from the patch, if any
73 byte[] d = data.get(i);
74 System.arraycopy(d, 0, rv, destIndex, d.length);
75 destIndex += d.length;
76 prevEnd = ends.get(i);
77 }
78 baseRevisionContent.seek(prevEnd);
79 // copy everything in the source past last record's end
80 baseRevisionContent.readBytes(rv, destIndex, (int) (baseRevisionContent.length() - prevEnd));
81 return rv;
82 }
83
84 public void clear() {
85 starts.clear();
86 ends.clear();
87 data.clear();
88 }
89
90 /**
91 * Initialize instance from stream. Any previous patch information (i.e. if instance if reused) is cleared first.
92 * Read up to the end of DataAccess and interpret data as patch records.
93 */
94 public void read(DataAccess da) throws IOException {
95 clear();
96 while (!da.isEmpty()) {
97 readOne(da);
98 }
99 }
100
101 /**
102 * Caller is responsible to ensure stream got some data to read
103 */
104 public void readOne(DataAccess da) throws IOException {
105 int s = da.readInt();
106 int e = da.readInt();
107 int len = da.readInt();
108 byte[] src = new byte[len];
109 da.readBytes(src, 0, len);
110 starts.add(s);
111 ends.add(e);
112 data.add(src);
113 }
114
115 /*
116 private void add(Patch another, int index) {
117 starts.add(another.starts.get(index));
118 ends.add(another.ends.get(index));
119 data.add(another.data.get(index));
120 }
121
122 /**
123 * Modify this patch with subsequent patch
124 * /
125 public void apply(Patch another) {
126 Patch r = new Patch();
127 int p1AppliedPos = 0;
128 int p1PrevEnd = 0;
129 for (int i = 0, j = 0, iMax = another.count(), jMax = this.count(); i < iMax; i++) {
130 int newerPatchEntryStart = another.starts.get(i);
131 int olderPatchEntryEnd;
132
133 while (j < jMax) {
134 if (starts.get(j) < newerPatchEntryStart) {
135 if (starts.get(j)+data.get(j).length <= newerPatchEntryStart) {
136 r.add(this, j);
137 } else {
138 int newLen = newerPatchEntryStart - starts.get(j);
139 int newEnd = ends.get(j) <= newerPatchEntryStart ? ends.get(j) : newerPatchEntryStart;
140 r.add(starts.get(j), newEnd, data.get(j), newLen);
141 break;
142 }
143 }
144 p1AppliedPos += starts.get(j) - p1PrevEnd;
145 p1AppliedPos += data.get(j).length;
146 p1PrevEnd = ends.get(j);
147 j++;
148 }
149 r.add(newerPatchEntryStart, another.ends.get(i), another.data.get(i));
150 p1AppliedPos += newerPatchEntryStart + p1PrevEnd - another.data.get(i).length;
151 // either j == jMax and another(i, i+1, ..., iMax) need to be just copied
152 // or new patch entry starts before end of one of original patch entries
153 if (olderPatchEntryEnd > (destPosition + newerPatchEntryStart)) {
154 destPosition += starts.get(j) - prevEnd; // count those in the original stream up to old patch start
155 int newLen = newerPatchEntryStart - destPosition;
156 }
157 }
158 }
159 */
160 }