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comparison src/com/tmate/hgkit/ll/RevlogStream.java @ 2:08db726a0fb7

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Shaping out low-level Hg structures
author Artem Tikhomirov <tikhomirov.artem@gmail.com>
date Sun, 19 Dec 2010 05:41:31 +0100
parents dbd663faec1f
children 24bb4f365164
comparison
equal deleted inserted replaced
1:a3576694a4d1 2:08db726a0fb7
2 * Copyright (c) 2010 Artem Tikhomirov 2 * Copyright (c) 2010 Artem Tikhomirov
3 */ 3 */
4 package com.tmate.hgkit.ll; 4 package com.tmate.hgkit.ll;
5 5
6 import java.io.DataInput; 6 import java.io.DataInput;
7 import java.io.EOFException;
8 import java.io.IOException;
9 import java.util.ArrayList;
10 import java.util.Collections;
11 import java.util.List;
12 import java.util.zip.Inflater;
7 13
8 /** 14 /**
9 * ? Single RevlogStream per file per repository with accessor to record access session (e.g. with back/forward operations), 15 * ? Single RevlogStream per file per repository with accessor to record access session (e.g. with back/forward operations),
10 * or numerous RevlogStream with separate representation of the underlaying data (cached, lazy ChunkStream)? 16 * or numerous RevlogStream with separate representation of the underlaying data (cached, lazy ChunkStream)?
11 * @author artem 17 * @author artem
12 * @see http://mercurial.selenic.com/wiki/Revlog 18 * @see http://mercurial.selenic.com/wiki/Revlog
13 * @see http://mercurial.selenic.com/wiki/RevlogNG 19 * @see http://mercurial.selenic.com/wiki/RevlogNG
14 */ 20 */
15 public class RevlogStream { 21 public class RevlogStream {
16 22
23 private List<IndexEntry> index; // indexed access highly needed
24 private boolean inline = false;
25
17 private void detectVersion() { 26 private void detectVersion() {
18 27
19 } 28 }
20 29
21 /*package*/ DataInput getIndexStream() { 30 /*package*/ DataInput getIndexStream() {
25 34
26 /*package*/ DataInput getDataStream() { 35 /*package*/ DataInput getDataStream() {
27 // TODO Auto-generated method stub 36 // TODO Auto-generated method stub
28 return null; 37 return null;
29 } 38 }
39 public int revisionCount() {
40 initOutline();
41 return index.size();
42 }
43
44 // should be possible to use TIP, ALL
45 public void iterate(int start, int end, boolean needData, Revlog.Inspector inspector) {
46 initOutline();
47 final int indexSize = index.size();
48 if (start < 0 || start >= indexSize) {
49 throw new IllegalArgumentException("Bad left range boundary " + start);
50 }
51 if (end < start || end >= indexSize) {
52 throw new IllegalArgumentException("Bad right range boundary " + end);
53 }
54 // XXX may cache [start .. end] from index with a single read (pre-read)
55
56 DataInput diIndex = null, diData = null;
57 diIndex = getIndexStream();
58 if (needData) {
59 diData = getDataStream();
60 }
61 try {
62 diIndex.skipBytes(inline ? (int) index.get(start).offset : start * 64);
63 for (int i = start; i <= end && i < indexSize; i++ ) {
64 IndexEntry ie = index.get(i);
65 long l = diIndex.readLong();
66 long offset = l >>> 16;
67 int flags = (int) (l & 0X0FFFF);
68 int compressedLen = diIndex.readInt();
69 int actualLen = diIndex.readInt();
70 int baseRevision = diIndex.readInt();
71 int linkRevision = diIndex.readInt();
72 int parent1Revision = diIndex.readInt();
73 int parent2Revision = diIndex.readInt();
74 byte[] buf = new byte[32];
75 // XXX Hg keeps 12 last bytes empty, we move them into front here
76 diIndex.readFully(buf, 12, 20);
77 diIndex.skipBytes(12);
78 byte[] data = null;
79 if (needData) {
80 byte[] dataBuf = new byte[compressedLen];
81 if (inline) {
82 diIndex.readFully(dataBuf);
83 } else {
84 diData.skipBytes((int) ie.offset); // FIXME not skip but seek!!!
85 diData.readFully(dataBuf);
86 }
87 if (dataBuf[0] == 0x78 /* 'x' */) {
88 Inflater zlib = new Inflater();
89 zlib.setInput(dataBuf, 0, compressedLen);
90 byte[] result = new byte[actualLen*2]; // FIXME need to use zlib.finished() instead
91 int resultLen = zlib.inflate(result);
92 zlib.end();
93 data = new byte[resultLen];
94 System.arraycopy(result, 0, data, 0, resultLen);
95 } else if (dataBuf[0] == 0x75 /* 'u' */) {
96 data = new byte[dataBuf.length - 1];
97 System.arraycopy(dataBuf, 1, data, 0, data.length);
98 } else {
99 // XXX Python impl in fact throws exception when there's not 'x', 'u' or '0'
100 // but I don't see reason not to just return data as is
101 data = dataBuf;
102 }
103 // FIXME if patch data (based on baseRevision), then apply patches to get true content
104 }
105 inspector.next(compressedLen, actualLen, baseRevision, linkRevision, parent1Revision, parent2Revision, buf, data);
106 }
107 } catch (EOFException ex) {
108 // should not happen as long as we read inside known boundaries
109 throw new IllegalStateException(ex);
110 } catch (IOException ex) {
111 FIXME
112 }
113 }
30 114
115 private void initOutline() {
116 if (index != null && !index.isEmpty()) {
117 return;
118 }
119 ArrayList<IndexEntry> res = new ArrayList<IndexEntry>();
120 DataInput di = getIndexStream();
121 try {
122 int versionField = di.readInt();
123 // di.undreadInt();
124 final int INLINEDATA = 1 << 16;
125 inline = (versionField & INLINEDATA) != 0;
126 long offset = 0; // first offset is always 0, thus Hg uses it for other purposes
127 while(true) { // EOFExcepiton should get us outta here. FIXME Out inputstream should has explicit no-more-data indicator
128 int compressedLen = di.readInt();
129 // 8+4 = 12 bytes total read
130 // int actualLen = di.readInt();
131 // int baseRevision = di.readInt();
132 // int linkRevision = di.readInt();
133 // int parent1Revision = di.readInt();
134 // int parent2Revision = di.readInt();
135 // byte[] nodeid = new byte[32];
136 res.add(new IndexEntry(offset, compressedLen));
137 if (inline) {
138 di.skipBytes(6*4 + 32 + compressedLen); // Check: 56 (skip) + 12 (read) = 64 (total RevlogNG record size)
139 } else {
140 di.skipBytes(6*4 + 32);
141 }
142 long l = di.readLong();
143 offset = l >>> 16;
144 }
145 } catch (EOFException ex) {
146 // fine, done then
147 index = res;
148 } catch (IOException ex) {
149 ex.printStackTrace();
150 // too bad, no outline then
151 index = Collections.emptyList();
152 }
153 }
154
155
156 // perhaps, package-local or protected, if anyone else from low-level needs them
157 private static class IndexEntry {
158 public final long offset;
159 public final int length; // data past fixed record (need to decide whether including header size or not), and whether length is of compressed data or not
160
161 public IndexEntry(long o, int l) {
162 offset = o;
163 length = l;
164 }
165 }
31 } 166 }