Mercurial > hg
annotate mercurial/mpatch.c @ 408:3695fbd2c33b
[PATCH] Merging files that are deleted in both branches
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[PATCH] Merging files that are deleted in both branches
From: Michael A Fetterman <Michael.Fetterman@cl.cam.ac.uk>
OK, attached is an improved version of this patch...
When I went back through it, I discovered that the prior version was wrong
when doing real merges (as opposed to jumping between revisions that have
a simple linear relationship). So that's been addressed here, too.
> Here's an hg changeset patch that deals with simultaneous deletion of a
file
> in both the working directory and in a merged branch.
>
> Test case included in the patch.
manifest hash: c8078733c252403314d8046efa6ecefc49c83050
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author | mpm@selenic.com |
---|---|
date | Tue, 21 Jun 2005 18:48:28 -0800 |
parents | a29decbf7475 |
children | 7c678976df3e 688d03d6997a |
rev | line source |
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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> | |
26 #include <netinet/in.h> | |
27 #include <sys/types.h> | |
28 | |
29 static char mpatch_doc[] = "Efficient binary patching."; | |
30 | |
31 struct frag { | |
32 int start, end, len; | |
33 char *data; | |
34 }; | |
35 | |
36 struct flist { | |
37 struct frag *base, *head, *tail; | |
38 }; | |
39 | |
40 static struct flist *lalloc(int size) | |
41 { | |
128 | 42 struct flist *a = NULL; |
72 | 43 |
44 a = malloc(sizeof(struct flist)); | |
128 | 45 if (a) { |
46 a->base = malloc(sizeof(struct frag) * size); | |
282 | 47 if (!a->base) { |
128 | 48 free(a); |
282 | 49 a = NULL; |
50 } else | |
128 | 51 a->head = a->tail = a->base; |
52 } | |
72 | 53 return a; |
54 } | |
55 | |
56 static void lfree(struct flist *a) | |
57 { | |
128 | 58 if (a) { |
59 free(a->base); | |
60 free(a); | |
61 } | |
72 | 62 } |
63 | |
64 static int lsize(struct flist *a) | |
65 { | |
66 return a->tail - a->head; | |
67 } | |
68 | |
69 /* move hunks in source that are less cut to dest, compensating | |
70 for changes in offset. the last hunk may be split if necessary. | |
71 */ | |
72 static int gather(struct flist *dest, struct flist *src, int cut, int offset) | |
73 { | |
74 struct frag *d = dest->tail, *s = src->head; | |
75 int postend, c, l; | |
76 | |
77 while (s != src->tail) { | |
78 if (s->start + offset >= cut) | |
82 | 79 break; /* we've gone far enough */ |
72 | 80 |
81 postend = offset + s->start + s->len; | |
82 if (postend <= cut) { | |
83 /* save this hunk */ | |
84 offset += s->start + s->len - s->end; | |
85 *d++ = *s++; | |
86 } | |
87 else { | |
88 /* break up this hunk */ | |
89 c = cut - offset; | |
90 if (s->end < c) | |
91 c = s->end; | |
92 l = cut - offset - s->start; | |
93 if (s->len < l) | |
94 l = s->len; | |
95 | |
96 offset += s->start + l - c; | |
97 | |
98 d->start = s->start; | |
99 d->end = c; | |
100 d->len = l; | |
101 d->data = s->data; | |
102 d++; | |
103 s->start = c; | |
104 s->len = s->len - l; | |
105 s->data = s->data + l; | |
106 | |
82 | 107 break; |
72 | 108 } |
109 } | |
110 | |
111 dest->tail = d; | |
112 src->head = s; | |
113 return offset; | |
114 } | |
115 | |
116 /* like gather, but with no output list */ | |
117 static int discard(struct flist *src, int cut, int offset) | |
118 { | |
119 struct frag *s = src->head; | |
120 int postend, c, l; | |
121 | |
122 while (s != src->tail) { | |
123 if (s->start + offset >= cut) | |
82 | 124 break; |
72 | 125 |
126 postend = offset + s->start + s->len; | |
127 if (postend <= cut) { | |
128 offset += s->start + s->len - s->end; | |
129 s++; | |
130 } | |
131 else { | |
132 c = cut - offset; | |
133 if (s->end < c) | |
134 c = s->end; | |
135 l = cut - offset - s->start; | |
136 if (s->len < l) | |
137 l = s->len; | |
138 | |
139 offset += s->start + l - c; | |
140 s->start = c; | |
141 s->len = s->len - l; | |
142 s->data = s->data + l; | |
143 | |
82 | 144 break; |
72 | 145 } |
146 } | |
147 | |
148 src->head = s; | |
149 return offset; | |
150 } | |
151 | |
152 /* combine hunk lists a and b, while adjusting b for offset changes in a/ | |
153 this deletes a and b and returns the resultant list. */ | |
154 static struct flist *combine(struct flist *a, struct flist *b) | |
155 { | |
128 | 156 struct flist *c = NULL; |
157 struct frag *bh, *ct; | |
72 | 158 int offset = 0, post; |
159 | |
128 | 160 if (a && b) |
161 c = lalloc((lsize(a) + lsize(b)) * 2); | |
162 | |
163 if (c) { | |
72 | 164 |
128 | 165 for (bh = b->head; bh != b->tail; bh++) { |
166 /* save old hunks */ | |
167 offset = gather(c, a, bh->start, offset); | |
72 | 168 |
128 | 169 /* discard replaced hunks */ |
170 post = discard(a, bh->end, offset); | |
72 | 171 |
128 | 172 /* insert new hunk */ |
173 ct = c->tail; | |
174 ct->start = bh->start - offset; | |
175 ct->end = bh->end - post; | |
176 ct->len = bh->len; | |
177 ct->data = bh->data; | |
178 c->tail++; | |
179 offset = post; | |
180 } | |
181 | |
182 /* hold on to tail from a */ | |
183 memcpy(c->tail, a->head, sizeof(struct frag) * lsize(a)); | |
184 c->tail += lsize(a); | |
72 | 185 } |
186 | |
187 lfree(a); | |
188 lfree(b); | |
189 return c; | |
190 } | |
191 | |
192 /* decode a binary patch into a hunk list */ | |
193 static struct flist *decode(char *bin, int len) | |
194 { | |
195 struct flist *l; | |
196 struct frag *lt; | |
197 char *end = bin + len; | |
384
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198 char decode[12]; /* for dealing with alignment issues */ |
72 | 199 |
200 /* assume worst case size, we won't have many of these lists */ | |
201 l = lalloc(len / 12); | |
202 lt = l->tail; | |
203 | |
204 while (bin < end) { | |
384
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205 memcpy(decode, bin, 12); |
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206 lt->start = ntohl(*(uint32_t *)decode); |
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207 lt->end = ntohl(*(uint32_t *)(decode + 4)); |
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208 lt->len = ntohl(*(uint32_t *)(decode + 8)); |
72 | 209 lt->data = bin + 12; |
210 bin += 12 + lt->len; | |
211 lt++; | |
212 } | |
213 | |
214 l->tail = lt; | |
215 return l; | |
216 } | |
217 | |
218 /* calculate the size of resultant text */ | |
219 static int calcsize(int len, struct flist *l) | |
220 { | |
221 int outlen = 0, last = 0; | |
222 struct frag *f = l->head; | |
223 | |
224 while (f != l->tail) { | |
225 outlen += f->start - last; | |
226 last = f->end; | |
227 outlen += f->len; | |
228 f++; | |
229 } | |
230 | |
231 outlen += len - last; | |
232 return outlen; | |
233 } | |
234 | |
235 static void apply(char *buf, char *orig, int len, struct flist *l) | |
236 { | |
237 struct frag *f = l->head; | |
238 int last = 0; | |
239 char *p = buf; | |
240 | |
241 while (f != l->tail) { | |
242 memcpy(p, orig + last, f->start - last); | |
243 p += f->start - last; | |
244 memcpy(p, f->data, f->len); | |
245 last = f->end; | |
246 p += f->len; | |
247 f++; | |
248 } | |
249 memcpy(p, orig + last, len - last); | |
250 } | |
251 | |
252 /* recursively generate a patch of all bins between start and end */ | |
253 static struct flist *fold(PyObject *bins, int start, int end) | |
254 { | |
255 int len; | |
256 | |
257 if (start + 1 == end) { | |
258 /* trivial case, output a decoded list */ | |
259 PyObject *tmp = PyList_GetItem(bins, start); | |
128 | 260 if (!tmp) |
261 return NULL; | |
72 | 262 return decode(PyString_AsString(tmp), PyString_Size(tmp)); |
263 } | |
264 | |
265 /* divide and conquer, memory management is elsewhere */ | |
266 len = (end - start) / 2; | |
267 return combine(fold(bins, start, start + len), | |
268 fold(bins, start + len, end)); | |
269 } | |
270 | |
271 static PyObject * | |
272 patches(PyObject *self, PyObject *args) | |
273 { | |
274 PyObject *text, *bins, *result; | |
275 struct flist *patch; | |
276 char *in, *out; | |
277 int len, outlen; | |
278 | |
128 | 279 if (!PyArg_ParseTuple(args, "SO:mpatch", &text, &bins)) |
72 | 280 return NULL; |
281 | |
282 len = PyList_Size(bins); | |
283 if (!len) { | |
284 /* nothing to do */ | |
285 Py_INCREF(text); | |
286 return text; | |
287 } | |
288 | |
289 patch = fold(bins, 0, len); | |
128 | 290 if (!patch) |
291 return PyErr_NoMemory(); | |
292 | |
72 | 293 outlen = calcsize(PyString_Size(text), patch); |
294 result = PyString_FromStringAndSize(NULL, outlen); | |
128 | 295 if (result) { |
296 in = PyString_AsString(text); | |
297 out = PyString_AsString(result); | |
298 apply(out, in, PyString_Size(text), patch); | |
299 } | |
300 | |
72 | 301 lfree(patch); |
302 return result; | |
303 } | |
304 | |
305 static PyMethodDef methods[] = { | |
306 {"patches", patches, METH_VARARGS, "apply a series of patches\n"}, | |
307 {NULL, NULL} | |
308 }; | |
309 | |
310 PyMODINIT_FUNC | |
311 initmpatch(void) | |
312 { | |
313 Py_InitModule3("mpatch", methods, mpatch_doc); | |
314 } | |
315 |