]>
Commit | Line | Data |
---|---|---|
a2ad79ce CC |
1 | #include "cache.h" |
2 | #include "commit.h" | |
3 | #include "diff.h" | |
4 | #include "revision.h" | |
5 | #include "bisect.h" | |
6 | ||
7 | /* bits #0-15 in revision.h */ | |
8 | ||
9 | #define COUNTED (1u<<16) | |
10 | ||
11 | /* | |
12 | * This is a truly stupid algorithm, but it's only | |
13 | * used for bisection, and we just don't care enough. | |
14 | * | |
15 | * We care just barely enough to avoid recursing for | |
16 | * non-merge entries. | |
17 | */ | |
18 | static int count_distance(struct commit_list *entry) | |
19 | { | |
20 | int nr = 0; | |
21 | ||
22 | while (entry) { | |
23 | struct commit *commit = entry->item; | |
24 | struct commit_list *p; | |
25 | ||
26 | if (commit->object.flags & (UNINTERESTING | COUNTED)) | |
27 | break; | |
28 | if (!(commit->object.flags & TREESAME)) | |
29 | nr++; | |
30 | commit->object.flags |= COUNTED; | |
31 | p = commit->parents; | |
32 | entry = p; | |
33 | if (p) { | |
34 | p = p->next; | |
35 | while (p) { | |
36 | nr += count_distance(p); | |
37 | p = p->next; | |
38 | } | |
39 | } | |
40 | } | |
41 | ||
42 | return nr; | |
43 | } | |
44 | ||
45 | static void clear_distance(struct commit_list *list) | |
46 | { | |
47 | while (list) { | |
48 | struct commit *commit = list->item; | |
49 | commit->object.flags &= ~COUNTED; | |
50 | list = list->next; | |
51 | } | |
52 | } | |
53 | ||
54 | #define DEBUG_BISECT 0 | |
55 | ||
56 | static inline int weight(struct commit_list *elem) | |
57 | { | |
58 | return *((int*)(elem->item->util)); | |
59 | } | |
60 | ||
61 | static inline void weight_set(struct commit_list *elem, int weight) | |
62 | { | |
63 | *((int*)(elem->item->util)) = weight; | |
64 | } | |
65 | ||
66 | static int count_interesting_parents(struct commit *commit) | |
67 | { | |
68 | struct commit_list *p; | |
69 | int count; | |
70 | ||
71 | for (count = 0, p = commit->parents; p; p = p->next) { | |
72 | if (p->item->object.flags & UNINTERESTING) | |
73 | continue; | |
74 | count++; | |
75 | } | |
76 | return count; | |
77 | } | |
78 | ||
79 | static inline int halfway(struct commit_list *p, int nr) | |
80 | { | |
81 | /* | |
82 | * Don't short-cut something we are not going to return! | |
83 | */ | |
84 | if (p->item->object.flags & TREESAME) | |
85 | return 0; | |
86 | if (DEBUG_BISECT) | |
87 | return 0; | |
88 | /* | |
89 | * 2 and 3 are halfway of 5. | |
90 | * 3 is halfway of 6 but 2 and 4 are not. | |
91 | */ | |
92 | switch (2 * weight(p) - nr) { | |
93 | case -1: case 0: case 1: | |
94 | return 1; | |
95 | default: | |
96 | return 0; | |
97 | } | |
98 | } | |
99 | ||
100 | #if !DEBUG_BISECT | |
101 | #define show_list(a,b,c,d) do { ; } while (0) | |
102 | #else | |
103 | static void show_list(const char *debug, int counted, int nr, | |
104 | struct commit_list *list) | |
105 | { | |
106 | struct commit_list *p; | |
107 | ||
108 | fprintf(stderr, "%s (%d/%d)\n", debug, counted, nr); | |
109 | ||
110 | for (p = list; p; p = p->next) { | |
111 | struct commit_list *pp; | |
112 | struct commit *commit = p->item; | |
113 | unsigned flags = commit->object.flags; | |
114 | enum object_type type; | |
115 | unsigned long size; | |
116 | char *buf = read_sha1_file(commit->object.sha1, &type, &size); | |
117 | char *ep, *sp; | |
118 | ||
119 | fprintf(stderr, "%c%c%c ", | |
120 | (flags & TREESAME) ? ' ' : 'T', | |
121 | (flags & UNINTERESTING) ? 'U' : ' ', | |
122 | (flags & COUNTED) ? 'C' : ' '); | |
123 | if (commit->util) | |
124 | fprintf(stderr, "%3d", weight(p)); | |
125 | else | |
126 | fprintf(stderr, "---"); | |
127 | fprintf(stderr, " %.*s", 8, sha1_to_hex(commit->object.sha1)); | |
128 | for (pp = commit->parents; pp; pp = pp->next) | |
129 | fprintf(stderr, " %.*s", 8, | |
130 | sha1_to_hex(pp->item->object.sha1)); | |
131 | ||
132 | sp = strstr(buf, "\n\n"); | |
133 | if (sp) { | |
134 | sp += 2; | |
135 | for (ep = sp; *ep && *ep != '\n'; ep++) | |
136 | ; | |
137 | fprintf(stderr, " %.*s", (int)(ep - sp), sp); | |
138 | } | |
139 | fprintf(stderr, "\n"); | |
140 | } | |
141 | } | |
142 | #endif /* DEBUG_BISECT */ | |
143 | ||
144 | static struct commit_list *best_bisection(struct commit_list *list, int nr) | |
145 | { | |
146 | struct commit_list *p, *best; | |
147 | int best_distance = -1; | |
148 | ||
149 | best = list; | |
150 | for (p = list; p; p = p->next) { | |
151 | int distance; | |
152 | unsigned flags = p->item->object.flags; | |
153 | ||
154 | if (flags & TREESAME) | |
155 | continue; | |
156 | distance = weight(p); | |
157 | if (nr - distance < distance) | |
158 | distance = nr - distance; | |
159 | if (distance > best_distance) { | |
160 | best = p; | |
161 | best_distance = distance; | |
162 | } | |
163 | } | |
164 | ||
165 | return best; | |
166 | } | |
167 | ||
168 | struct commit_dist { | |
169 | struct commit *commit; | |
170 | int distance; | |
171 | }; | |
172 | ||
173 | static int compare_commit_dist(const void *a_, const void *b_) | |
174 | { | |
175 | struct commit_dist *a, *b; | |
176 | ||
177 | a = (struct commit_dist *)a_; | |
178 | b = (struct commit_dist *)b_; | |
179 | if (a->distance != b->distance) | |
180 | return b->distance - a->distance; /* desc sort */ | |
181 | return hashcmp(a->commit->object.sha1, b->commit->object.sha1); | |
182 | } | |
183 | ||
184 | static struct commit_list *best_bisection_sorted(struct commit_list *list, int nr) | |
185 | { | |
186 | struct commit_list *p; | |
187 | struct commit_dist *array = xcalloc(nr, sizeof(*array)); | |
188 | int cnt, i; | |
189 | ||
190 | for (p = list, cnt = 0; p; p = p->next) { | |
191 | int distance; | |
192 | unsigned flags = p->item->object.flags; | |
193 | ||
194 | if (flags & TREESAME) | |
195 | continue; | |
196 | distance = weight(p); | |
197 | if (nr - distance < distance) | |
198 | distance = nr - distance; | |
199 | array[cnt].commit = p->item; | |
200 | array[cnt].distance = distance; | |
201 | cnt++; | |
202 | } | |
203 | qsort(array, cnt, sizeof(*array), compare_commit_dist); | |
204 | for (p = list, i = 0; i < cnt; i++) { | |
205 | struct name_decoration *r = xmalloc(sizeof(*r) + 100); | |
206 | struct object *obj = &(array[i].commit->object); | |
207 | ||
208 | sprintf(r->name, "dist=%d", array[i].distance); | |
209 | r->next = add_decoration(&name_decoration, obj, r); | |
210 | p->item = array[i].commit; | |
211 | p = p->next; | |
212 | } | |
213 | if (p) | |
214 | p->next = NULL; | |
215 | free(array); | |
216 | return list; | |
217 | } | |
218 | ||
219 | /* | |
220 | * zero or positive weight is the number of interesting commits it can | |
221 | * reach, including itself. Especially, weight = 0 means it does not | |
222 | * reach any tree-changing commits (e.g. just above uninteresting one | |
223 | * but traversal is with pathspec). | |
224 | * | |
225 | * weight = -1 means it has one parent and its distance is yet to | |
226 | * be computed. | |
227 | * | |
228 | * weight = -2 means it has more than one parent and its distance is | |
229 | * unknown. After running count_distance() first, they will get zero | |
230 | * or positive distance. | |
231 | */ | |
232 | static struct commit_list *do_find_bisection(struct commit_list *list, | |
233 | int nr, int *weights, | |
234 | int find_all) | |
235 | { | |
236 | int n, counted; | |
237 | struct commit_list *p; | |
238 | ||
239 | counted = 0; | |
240 | ||
241 | for (n = 0, p = list; p; p = p->next) { | |
242 | struct commit *commit = p->item; | |
243 | unsigned flags = commit->object.flags; | |
244 | ||
245 | p->item->util = &weights[n++]; | |
246 | switch (count_interesting_parents(commit)) { | |
247 | case 0: | |
248 | if (!(flags & TREESAME)) { | |
249 | weight_set(p, 1); | |
250 | counted++; | |
251 | show_list("bisection 2 count one", | |
252 | counted, nr, list); | |
253 | } | |
254 | /* | |
255 | * otherwise, it is known not to reach any | |
256 | * tree-changing commit and gets weight 0. | |
257 | */ | |
258 | break; | |
259 | case 1: | |
260 | weight_set(p, -1); | |
261 | break; | |
262 | default: | |
263 | weight_set(p, -2); | |
264 | break; | |
265 | } | |
266 | } | |
267 | ||
268 | show_list("bisection 2 initialize", counted, nr, list); | |
269 | ||
270 | /* | |
271 | * If you have only one parent in the resulting set | |
272 | * then you can reach one commit more than that parent | |
273 | * can reach. So we do not have to run the expensive | |
274 | * count_distance() for single strand of pearls. | |
275 | * | |
276 | * However, if you have more than one parents, you cannot | |
277 | * just add their distance and one for yourself, since | |
278 | * they usually reach the same ancestor and you would | |
279 | * end up counting them twice that way. | |
280 | * | |
281 | * So we will first count distance of merges the usual | |
282 | * way, and then fill the blanks using cheaper algorithm. | |
283 | */ | |
284 | for (p = list; p; p = p->next) { | |
285 | if (p->item->object.flags & UNINTERESTING) | |
286 | continue; | |
287 | if (weight(p) != -2) | |
288 | continue; | |
289 | weight_set(p, count_distance(p)); | |
290 | clear_distance(list); | |
291 | ||
292 | /* Does it happen to be at exactly half-way? */ | |
293 | if (!find_all && halfway(p, nr)) | |
294 | return p; | |
295 | counted++; | |
296 | } | |
297 | ||
298 | show_list("bisection 2 count_distance", counted, nr, list); | |
299 | ||
300 | while (counted < nr) { | |
301 | for (p = list; p; p = p->next) { | |
302 | struct commit_list *q; | |
303 | unsigned flags = p->item->object.flags; | |
304 | ||
305 | if (0 <= weight(p)) | |
306 | continue; | |
307 | for (q = p->item->parents; q; q = q->next) { | |
308 | if (q->item->object.flags & UNINTERESTING) | |
309 | continue; | |
310 | if (0 <= weight(q)) | |
311 | break; | |
312 | } | |
313 | if (!q) | |
314 | continue; | |
315 | ||
316 | /* | |
317 | * weight for p is unknown but q is known. | |
318 | * add one for p itself if p is to be counted, | |
319 | * otherwise inherit it from q directly. | |
320 | */ | |
321 | if (!(flags & TREESAME)) { | |
322 | weight_set(p, weight(q)+1); | |
323 | counted++; | |
324 | show_list("bisection 2 count one", | |
325 | counted, nr, list); | |
326 | } | |
327 | else | |
328 | weight_set(p, weight(q)); | |
329 | ||
330 | /* Does it happen to be at exactly half-way? */ | |
331 | if (!find_all && halfway(p, nr)) | |
332 | return p; | |
333 | } | |
334 | } | |
335 | ||
336 | show_list("bisection 2 counted all", counted, nr, list); | |
337 | ||
338 | if (!find_all) | |
339 | return best_bisection(list, nr); | |
340 | else | |
341 | return best_bisection_sorted(list, nr); | |
342 | } | |
343 | ||
344 | struct commit_list *find_bisection(struct commit_list *list, | |
345 | int *reaches, int *all, | |
346 | int find_all) | |
347 | { | |
348 | int nr, on_list; | |
349 | struct commit_list *p, *best, *next, *last; | |
350 | int *weights; | |
351 | ||
352 | show_list("bisection 2 entry", 0, 0, list); | |
353 | ||
354 | /* | |
355 | * Count the number of total and tree-changing items on the | |
356 | * list, while reversing the list. | |
357 | */ | |
358 | for (nr = on_list = 0, last = NULL, p = list; | |
359 | p; | |
360 | p = next) { | |
361 | unsigned flags = p->item->object.flags; | |
362 | ||
363 | next = p->next; | |
364 | if (flags & UNINTERESTING) | |
365 | continue; | |
366 | p->next = last; | |
367 | last = p; | |
368 | if (!(flags & TREESAME)) | |
369 | nr++; | |
370 | on_list++; | |
371 | } | |
372 | list = last; | |
373 | show_list("bisection 2 sorted", 0, nr, list); | |
374 | ||
375 | *all = nr; | |
376 | weights = xcalloc(on_list, sizeof(*weights)); | |
377 | ||
378 | /* Do the real work of finding bisection commit. */ | |
379 | best = do_find_bisection(list, nr, weights, find_all); | |
380 | if (best) { | |
381 | if (!find_all) | |
382 | best->next = NULL; | |
383 | *reaches = weight(best); | |
384 | } | |
385 | free(weights); | |
386 | return best; | |
387 | } | |
388 |