Mercurial > hg > mercurial-crew-with-dirclash
annotate mercurial/mpatch.c @ 1039:4296754ba7b4
Add debugdata for dumping revlog revision data
author | mpm@selenic.com |
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date | Wed, 24 Aug 2005 18:40:17 -0700 |
parents | e530637ea060 |
children | 681c5c211b92 |
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72 | 1 /* |
2 mpatch.c - efficient binary patching for Mercurial | |
3 | |
4 This implements a patch algorithm that's O(m + nlog n) where m is the | |
5 size of the output and n is the number of patches. | |
6 | |
7 Given a list of binary patches, it unpacks each into a hunk list, | |
8 then combines the hunk lists with a treewise recursion to form a | |
9 single hunk list. This hunk list is then applied to the original | |
10 text. | |
11 | |
12 The text (or binary) fragments are copied directly from their source | |
13 Python objects into a preallocated output string to avoid the | |
14 allocation of intermediate Python objects. Working memory is about 2x | |
15 the total number of hunks. | |
16 | |
17 Copyright 2005 Matt Mackall <mpm@selenic.com> | |
18 | |
19 This software may be used and distributed according to the terms | |
20 of the GNU General Public License, incorporated herein by reference. | |
21 */ | |
22 | |
23 #include <Python.h> | |
24 #include <stdlib.h> | |
25 #include <string.h> | |
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26 #ifdef _WIN32 |
551 | 27 #ifdef _MSC_VER |
28 #define inline __inline | |
29 typedef unsigned long uint32_t; | |
30 #else | |
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31 #include <stdint.h> |
551 | 32 #endif |
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33 static uint32_t ntohl(uint32_t x) |
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34 { |
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35 return ((x & 0x000000ffUL) << 24) | |
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36 ((x & 0x0000ff00UL) << 8) | |
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37 ((x & 0x00ff0000UL) >> 8) | |
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38 ((x & 0xff000000UL) >> 24); |
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39 } |
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40 #else |
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41 #include <sys/types.h> |
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42 #include <arpa/inet.h> |
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43 #endif |
72 | 44 |
45 static char mpatch_doc[] = "Efficient binary patching."; | |
46 | |
47 struct frag { | |
48 int start, end, len; | |
49 char *data; | |
50 }; | |
51 | |
52 struct flist { | |
53 struct frag *base, *head, *tail; | |
54 }; | |
55 | |
56 static struct flist *lalloc(int size) | |
57 { | |
128 | 58 struct flist *a = NULL; |
72 | 59 |
60 a = malloc(sizeof(struct flist)); | |
128 | 61 if (a) { |
62 a->base = malloc(sizeof(struct frag) * size); | |
282 | 63 if (!a->base) { |
128 | 64 free(a); |
282 | 65 a = NULL; |
66 } else | |
128 | 67 a->head = a->tail = a->base; |
68 } | |
72 | 69 return a; |
70 } | |
71 | |
72 static void lfree(struct flist *a) | |
73 { | |
128 | 74 if (a) { |
75 free(a->base); | |
76 free(a); | |
77 } | |
72 | 78 } |
79 | |
80 static int lsize(struct flist *a) | |
81 { | |
82 return a->tail - a->head; | |
83 } | |
84 | |
85 /* move hunks in source that are less cut to dest, compensating | |
86 for changes in offset. the last hunk may be split if necessary. | |
87 */ | |
88 static int gather(struct flist *dest, struct flist *src, int cut, int offset) | |
89 { | |
90 struct frag *d = dest->tail, *s = src->head; | |
91 int postend, c, l; | |
92 | |
93 while (s != src->tail) { | |
94 if (s->start + offset >= cut) | |
82 | 95 break; /* we've gone far enough */ |
72 | 96 |
97 postend = offset + s->start + s->len; | |
98 if (postend <= cut) { | |
99 /* save this hunk */ | |
100 offset += s->start + s->len - s->end; | |
101 *d++ = *s++; | |
102 } | |
103 else { | |
104 /* break up this hunk */ | |
105 c = cut - offset; | |
106 if (s->end < c) | |
107 c = s->end; | |
108 l = cut - offset - s->start; | |
109 if (s->len < l) | |
110 l = s->len; | |
111 | |
112 offset += s->start + l - c; | |
113 | |
114 d->start = s->start; | |
115 d->end = c; | |
116 d->len = l; | |
117 d->data = s->data; | |
118 d++; | |
119 s->start = c; | |
120 s->len = s->len - l; | |
121 s->data = s->data + l; | |
122 | |
82 | 123 break; |
72 | 124 } |
125 } | |
126 | |
127 dest->tail = d; | |
128 src->head = s; | |
129 return offset; | |
130 } | |
131 | |
132 /* like gather, but with no output list */ | |
133 static int discard(struct flist *src, int cut, int offset) | |
134 { | |
135 struct frag *s = src->head; | |
136 int postend, c, l; | |
137 | |
138 while (s != src->tail) { | |
139 if (s->start + offset >= cut) | |
82 | 140 break; |
72 | 141 |
142 postend = offset + s->start + s->len; | |
143 if (postend <= cut) { | |
144 offset += s->start + s->len - s->end; | |
145 s++; | |
146 } | |
147 else { | |
148 c = cut - offset; | |
149 if (s->end < c) | |
150 c = s->end; | |
151 l = cut - offset - s->start; | |
152 if (s->len < l) | |
153 l = s->len; | |
154 | |
155 offset += s->start + l - c; | |
156 s->start = c; | |
157 s->len = s->len - l; | |
158 s->data = s->data + l; | |
159 | |
82 | 160 break; |
72 | 161 } |
162 } | |
163 | |
164 src->head = s; | |
165 return offset; | |
166 } | |
167 | |
168 /* combine hunk lists a and b, while adjusting b for offset changes in a/ | |
169 this deletes a and b and returns the resultant list. */ | |
170 static struct flist *combine(struct flist *a, struct flist *b) | |
171 { | |
128 | 172 struct flist *c = NULL; |
173 struct frag *bh, *ct; | |
72 | 174 int offset = 0, post; |
175 | |
128 | 176 if (a && b) |
177 c = lalloc((lsize(a) + lsize(b)) * 2); | |
178 | |
179 if (c) { | |
72 | 180 |
128 | 181 for (bh = b->head; bh != b->tail; bh++) { |
182 /* save old hunks */ | |
183 offset = gather(c, a, bh->start, offset); | |
72 | 184 |
128 | 185 /* discard replaced hunks */ |
186 post = discard(a, bh->end, offset); | |
72 | 187 |
128 | 188 /* insert new hunk */ |
189 ct = c->tail; | |
190 ct->start = bh->start - offset; | |
191 ct->end = bh->end - post; | |
192 ct->len = bh->len; | |
193 ct->data = bh->data; | |
194 c->tail++; | |
195 offset = post; | |
196 } | |
197 | |
198 /* hold on to tail from a */ | |
199 memcpy(c->tail, a->head, sizeof(struct frag) * lsize(a)); | |
200 c->tail += lsize(a); | |
72 | 201 } |
202 | |
203 lfree(a); | |
204 lfree(b); | |
205 return c; | |
206 } | |
207 | |
208 /* decode a binary patch into a hunk list */ | |
209 static struct flist *decode(char *bin, int len) | |
210 { | |
211 struct flist *l; | |
212 struct frag *lt; | |
213 char *end = bin + len; | |
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214 char decode[12]; /* for dealing with alignment issues */ |
72 | 215 |
216 /* assume worst case size, we won't have many of these lists */ | |
217 l = lalloc(len / 12); | |
218 lt = l->tail; | |
219 | |
220 while (bin < end) { | |
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221 memcpy(decode, bin, 12); |
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222 lt->start = ntohl(*(uint32_t *)decode); |
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223 lt->end = ntohl(*(uint32_t *)(decode + 4)); |
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224 lt->len = ntohl(*(uint32_t *)(decode + 8)); |
72 | 225 lt->data = bin + 12; |
226 bin += 12 + lt->len; | |
227 lt++; | |
228 } | |
229 | |
230 l->tail = lt; | |
231 return l; | |
232 } | |
233 | |
234 /* calculate the size of resultant text */ | |
235 static int calcsize(int len, struct flist *l) | |
236 { | |
237 int outlen = 0, last = 0; | |
238 struct frag *f = l->head; | |
239 | |
240 while (f != l->tail) { | |
241 outlen += f->start - last; | |
242 last = f->end; | |
243 outlen += f->len; | |
244 f++; | |
245 } | |
246 | |
247 outlen += len - last; | |
248 return outlen; | |
249 } | |
250 | |
251 static void apply(char *buf, char *orig, int len, struct flist *l) | |
252 { | |
253 struct frag *f = l->head; | |
254 int last = 0; | |
255 char *p = buf; | |
256 | |
257 while (f != l->tail) { | |
258 memcpy(p, orig + last, f->start - last); | |
259 p += f->start - last; | |
260 memcpy(p, f->data, f->len); | |
261 last = f->end; | |
262 p += f->len; | |
263 f++; | |
264 } | |
265 memcpy(p, orig + last, len - last); | |
266 } | |
267 | |
268 /* recursively generate a patch of all bins between start and end */ | |
269 static struct flist *fold(PyObject *bins, int start, int end) | |
270 { | |
271 int len; | |
272 | |
273 if (start + 1 == end) { | |
274 /* trivial case, output a decoded list */ | |
275 PyObject *tmp = PyList_GetItem(bins, start); | |
128 | 276 if (!tmp) |
277 return NULL; | |
72 | 278 return decode(PyString_AsString(tmp), PyString_Size(tmp)); |
279 } | |
280 | |
281 /* divide and conquer, memory management is elsewhere */ | |
282 len = (end - start) / 2; | |
283 return combine(fold(bins, start, start + len), | |
284 fold(bins, start + len, end)); | |
285 } | |
286 | |
287 static PyObject * | |
288 patches(PyObject *self, PyObject *args) | |
289 { | |
290 PyObject *text, *bins, *result; | |
291 struct flist *patch; | |
292 char *in, *out; | |
293 int len, outlen; | |
294 | |
128 | 295 if (!PyArg_ParseTuple(args, "SO:mpatch", &text, &bins)) |
72 | 296 return NULL; |
297 | |
298 len = PyList_Size(bins); | |
299 if (!len) { | |
300 /* nothing to do */ | |
301 Py_INCREF(text); | |
302 return text; | |
303 } | |
304 | |
305 patch = fold(bins, 0, len); | |
128 | 306 if (!patch) |
307 return PyErr_NoMemory(); | |
308 | |
72 | 309 outlen = calcsize(PyString_Size(text), patch); |
310 result = PyString_FromStringAndSize(NULL, outlen); | |
128 | 311 if (result) { |
312 in = PyString_AsString(text); | |
313 out = PyString_AsString(result); | |
314 apply(out, in, PyString_Size(text), patch); | |
315 } | |
316 | |
72 | 317 lfree(patch); |
318 return result; | |
319 } | |
320 | |
321 static PyMethodDef methods[] = { | |
322 {"patches", patches, METH_VARARGS, "apply a series of patches\n"}, | |
323 {NULL, NULL} | |
324 }; | |
325 | |
326 PyMODINIT_FUNC | |
327 initmpatch(void) | |
328 { | |
329 Py_InitModule3("mpatch", methods, mpatch_doc); | |
330 } | |
331 |