Merge branch 'pk/rebase-in-c-2-basic'
[git] / commit-reach.c
1 #include "cache.h"
2 #include "commit.h"
3 #include "commit-graph.h"
4 #include "decorate.h"
5 #include "prio-queue.h"
6 #include "tree.h"
7 #include "ref-filter.h"
8 #include "revision.h"
9 #include "tag.h"
10 #include "commit-reach.h"
11
12 /* Remember to update object flag allocation in object.h */
13 #define REACHABLE       (1u<<15)
14 #define PARENT1         (1u<<16)
15 #define PARENT2         (1u<<17)
16 #define STALE           (1u<<18)
17 #define RESULT          (1u<<19)
18
19 static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
20
21 static int queue_has_nonstale(struct prio_queue *queue)
22 {
23         int i;
24         for (i = 0; i < queue->nr; i++) {
25                 struct commit *commit = queue->array[i].data;
26                 if (!(commit->object.flags & STALE))
27                         return 1;
28         }
29         return 0;
30 }
31
32 /* all input commits in one and twos[] must have been parsed! */
33 static struct commit_list *paint_down_to_common(struct commit *one, int n,
34                                                 struct commit **twos,
35                                                 int min_generation)
36 {
37         struct prio_queue queue = { compare_commits_by_gen_then_commit_date };
38         struct commit_list *result = NULL;
39         int i;
40         uint32_t last_gen = GENERATION_NUMBER_INFINITY;
41
42         if (!min_generation)
43                 queue.compare = compare_commits_by_commit_date;
44
45         one->object.flags |= PARENT1;
46         if (!n) {
47                 commit_list_append(one, &result);
48                 return result;
49         }
50         prio_queue_put(&queue, one);
51
52         for (i = 0; i < n; i++) {
53                 twos[i]->object.flags |= PARENT2;
54                 prio_queue_put(&queue, twos[i]);
55         }
56
57         while (queue_has_nonstale(&queue)) {
58                 struct commit *commit = prio_queue_get(&queue);
59                 struct commit_list *parents;
60                 int flags;
61
62                 if (min_generation && commit->generation > last_gen)
63                         BUG("bad generation skip %8x > %8x at %s",
64                             commit->generation, last_gen,
65                             oid_to_hex(&commit->object.oid));
66                 last_gen = commit->generation;
67
68                 if (commit->generation < min_generation)
69                         break;
70
71                 flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
72                 if (flags == (PARENT1 | PARENT2)) {
73                         if (!(commit->object.flags & RESULT)) {
74                                 commit->object.flags |= RESULT;
75                                 commit_list_insert_by_date(commit, &result);
76                         }
77                         /* Mark parents of a found merge stale */
78                         flags |= STALE;
79                 }
80                 parents = commit->parents;
81                 while (parents) {
82                         struct commit *p = parents->item;
83                         parents = parents->next;
84                         if ((p->object.flags & flags) == flags)
85                                 continue;
86                         if (parse_commit(p))
87                                 return NULL;
88                         p->object.flags |= flags;
89                         prio_queue_put(&queue, p);
90                 }
91         }
92
93         clear_prio_queue(&queue);
94         return result;
95 }
96
97 static struct commit_list *merge_bases_many(struct commit *one, int n, struct commit **twos)
98 {
99         struct commit_list *list = NULL;
100         struct commit_list *result = NULL;
101         int i;
102
103         for (i = 0; i < n; i++) {
104                 if (one == twos[i])
105                         /*
106                          * We do not mark this even with RESULT so we do not
107                          * have to clean it up.
108                          */
109                         return commit_list_insert(one, &result);
110         }
111
112         if (parse_commit(one))
113                 return NULL;
114         for (i = 0; i < n; i++) {
115                 if (parse_commit(twos[i]))
116                         return NULL;
117         }
118
119         list = paint_down_to_common(one, n, twos, 0);
120
121         while (list) {
122                 struct commit *commit = pop_commit(&list);
123                 if (!(commit->object.flags & STALE))
124                         commit_list_insert_by_date(commit, &result);
125         }
126         return result;
127 }
128
129 struct commit_list *get_octopus_merge_bases(struct commit_list *in)
130 {
131         struct commit_list *i, *j, *k, *ret = NULL;
132
133         if (!in)
134                 return ret;
135
136         commit_list_insert(in->item, &ret);
137
138         for (i = in->next; i; i = i->next) {
139                 struct commit_list *new_commits = NULL, *end = NULL;
140
141                 for (j = ret; j; j = j->next) {
142                         struct commit_list *bases;
143                         bases = get_merge_bases(i->item, j->item);
144                         if (!new_commits)
145                                 new_commits = bases;
146                         else
147                                 end->next = bases;
148                         for (k = bases; k; k = k->next)
149                                 end = k;
150                 }
151                 ret = new_commits;
152         }
153         return ret;
154 }
155
156 static int remove_redundant(struct commit **array, int cnt)
157 {
158         /*
159          * Some commit in the array may be an ancestor of
160          * another commit.  Move such commit to the end of
161          * the array, and return the number of commits that
162          * are independent from each other.
163          */
164         struct commit **work;
165         unsigned char *redundant;
166         int *filled_index;
167         int i, j, filled;
168
169         work = xcalloc(cnt, sizeof(*work));
170         redundant = xcalloc(cnt, 1);
171         ALLOC_ARRAY(filled_index, cnt - 1);
172
173         for (i = 0; i < cnt; i++)
174                 parse_commit(array[i]);
175         for (i = 0; i < cnt; i++) {
176                 struct commit_list *common;
177                 uint32_t min_generation = array[i]->generation;
178
179                 if (redundant[i])
180                         continue;
181                 for (j = filled = 0; j < cnt; j++) {
182                         if (i == j || redundant[j])
183                                 continue;
184                         filled_index[filled] = j;
185                         work[filled++] = array[j];
186
187                         if (array[j]->generation < min_generation)
188                                 min_generation = array[j]->generation;
189                 }
190                 common = paint_down_to_common(array[i], filled, work,
191                                               min_generation);
192                 if (array[i]->object.flags & PARENT2)
193                         redundant[i] = 1;
194                 for (j = 0; j < filled; j++)
195                         if (work[j]->object.flags & PARENT1)
196                                 redundant[filled_index[j]] = 1;
197                 clear_commit_marks(array[i], all_flags);
198                 clear_commit_marks_many(filled, work, all_flags);
199                 free_commit_list(common);
200         }
201
202         /* Now collect the result */
203         COPY_ARRAY(work, array, cnt);
204         for (i = filled = 0; i < cnt; i++)
205                 if (!redundant[i])
206                         array[filled++] = work[i];
207         for (j = filled, i = 0; i < cnt; i++)
208                 if (redundant[i])
209                         array[j++] = work[i];
210         free(work);
211         free(redundant);
212         free(filled_index);
213         return filled;
214 }
215
216 static struct commit_list *get_merge_bases_many_0(struct commit *one,
217                                                   int n,
218                                                   struct commit **twos,
219                                                   int cleanup)
220 {
221         struct commit_list *list;
222         struct commit **rslt;
223         struct commit_list *result;
224         int cnt, i;
225
226         result = merge_bases_many(one, n, twos);
227         for (i = 0; i < n; i++) {
228                 if (one == twos[i])
229                         return result;
230         }
231         if (!result || !result->next) {
232                 if (cleanup) {
233                         clear_commit_marks(one, all_flags);
234                         clear_commit_marks_many(n, twos, all_flags);
235                 }
236                 return result;
237         }
238
239         /* There are more than one */
240         cnt = commit_list_count(result);
241         rslt = xcalloc(cnt, sizeof(*rslt));
242         for (list = result, i = 0; list; list = list->next)
243                 rslt[i++] = list->item;
244         free_commit_list(result);
245
246         clear_commit_marks(one, all_flags);
247         clear_commit_marks_many(n, twos, all_flags);
248
249         cnt = remove_redundant(rslt, cnt);
250         result = NULL;
251         for (i = 0; i < cnt; i++)
252                 commit_list_insert_by_date(rslt[i], &result);
253         free(rslt);
254         return result;
255 }
256
257 struct commit_list *get_merge_bases_many(struct commit *one,
258                                          int n,
259                                          struct commit **twos)
260 {
261         return get_merge_bases_many_0(one, n, twos, 1);
262 }
263
264 struct commit_list *get_merge_bases_many_dirty(struct commit *one,
265                                                int n,
266                                                struct commit **twos)
267 {
268         return get_merge_bases_many_0(one, n, twos, 0);
269 }
270
271 struct commit_list *get_merge_bases(struct commit *one, struct commit *two)
272 {
273         return get_merge_bases_many_0(one, 1, &two, 1);
274 }
275
276 /*
277  * Is "commit" a descendant of one of the elements on the "with_commit" list?
278  */
279 int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
280 {
281         if (!with_commit)
282                 return 1;
283
284         if (generation_numbers_enabled(the_repository)) {
285                 struct commit_list *from_list = NULL;
286                 int result;
287                 commit_list_insert(commit, &from_list);
288                 result = can_all_from_reach(from_list, with_commit, 0);
289                 free_commit_list(from_list);
290                 return result;
291         } else {
292                 while (with_commit) {
293                         struct commit *other;
294
295                         other = with_commit->item;
296                         with_commit = with_commit->next;
297                         if (in_merge_bases(other, commit))
298                                 return 1;
299                 }
300                 return 0;
301         }
302 }
303
304 /*
305  * Is "commit" an ancestor of one of the "references"?
306  */
307 int in_merge_bases_many(struct commit *commit, int nr_reference, struct commit **reference)
308 {
309         struct commit_list *bases;
310         int ret = 0, i;
311         uint32_t min_generation = GENERATION_NUMBER_INFINITY;
312
313         if (parse_commit(commit))
314                 return ret;
315         for (i = 0; i < nr_reference; i++) {
316                 if (parse_commit(reference[i]))
317                         return ret;
318                 if (reference[i]->generation < min_generation)
319                         min_generation = reference[i]->generation;
320         }
321
322         if (commit->generation > min_generation)
323                 return ret;
324
325         bases = paint_down_to_common(commit, nr_reference, reference, commit->generation);
326         if (commit->object.flags & PARENT2)
327                 ret = 1;
328         clear_commit_marks(commit, all_flags);
329         clear_commit_marks_many(nr_reference, reference, all_flags);
330         free_commit_list(bases);
331         return ret;
332 }
333
334 /*
335  * Is "commit" an ancestor of (i.e. reachable from) the "reference"?
336  */
337 int in_merge_bases(struct commit *commit, struct commit *reference)
338 {
339         return in_merge_bases_many(commit, 1, &reference);
340 }
341
342 struct commit_list *reduce_heads(struct commit_list *heads)
343 {
344         struct commit_list *p;
345         struct commit_list *result = NULL, **tail = &result;
346         struct commit **array;
347         int num_head, i;
348
349         if (!heads)
350                 return NULL;
351
352         /* Uniquify */
353         for (p = heads; p; p = p->next)
354                 p->item->object.flags &= ~STALE;
355         for (p = heads, num_head = 0; p; p = p->next) {
356                 if (p->item->object.flags & STALE)
357                         continue;
358                 p->item->object.flags |= STALE;
359                 num_head++;
360         }
361         array = xcalloc(num_head, sizeof(*array));
362         for (p = heads, i = 0; p; p = p->next) {
363                 if (p->item->object.flags & STALE) {
364                         array[i++] = p->item;
365                         p->item->object.flags &= ~STALE;
366                 }
367         }
368         num_head = remove_redundant(array, num_head);
369         for (i = 0; i < num_head; i++)
370                 tail = &commit_list_insert(array[i], tail)->next;
371         free(array);
372         return result;
373 }
374
375 void reduce_heads_replace(struct commit_list **heads)
376 {
377         struct commit_list *result = reduce_heads(*heads);
378         free_commit_list(*heads);
379         *heads = result;
380 }
381
382 int ref_newer(const struct object_id *new_oid, const struct object_id *old_oid)
383 {
384         struct object *o;
385         struct commit *old_commit, *new_commit;
386         struct commit_list *old_commit_list = NULL;
387
388         /*
389          * Both new_commit and old_commit must be commit-ish and new_commit is descendant of
390          * old_commit.  Otherwise we require --force.
391          */
392         o = deref_tag(the_repository, parse_object(the_repository, old_oid),
393                       NULL, 0);
394         if (!o || o->type != OBJ_COMMIT)
395                 return 0;
396         old_commit = (struct commit *) o;
397
398         o = deref_tag(the_repository, parse_object(the_repository, new_oid),
399                       NULL, 0);
400         if (!o || o->type != OBJ_COMMIT)
401                 return 0;
402         new_commit = (struct commit *) o;
403
404         if (parse_commit(new_commit) < 0)
405                 return 0;
406
407         commit_list_insert(old_commit, &old_commit_list);
408         return is_descendant_of(new_commit, old_commit_list);
409 }
410
411 /*
412  * Mimicking the real stack, this stack lives on the heap, avoiding stack
413  * overflows.
414  *
415  * At each recursion step, the stack items points to the commits whose
416  * ancestors are to be inspected.
417  */
418 struct contains_stack {
419         int nr, alloc;
420         struct contains_stack_entry {
421                 struct commit *commit;
422                 struct commit_list *parents;
423         } *contains_stack;
424 };
425
426 static int in_commit_list(const struct commit_list *want, struct commit *c)
427 {
428         for (; want; want = want->next)
429                 if (oideq(&want->item->object.oid, &c->object.oid))
430                         return 1;
431         return 0;
432 }
433
434 /*
435  * Test whether the candidate is contained in the list.
436  * Do not recurse to find out, though, but return -1 if inconclusive.
437  */
438 static enum contains_result contains_test(struct commit *candidate,
439                                           const struct commit_list *want,
440                                           struct contains_cache *cache,
441                                           uint32_t cutoff)
442 {
443         enum contains_result *cached = contains_cache_at(cache, candidate);
444
445         /* If we already have the answer cached, return that. */
446         if (*cached)
447                 return *cached;
448
449         /* or are we it? */
450         if (in_commit_list(want, candidate)) {
451                 *cached = CONTAINS_YES;
452                 return CONTAINS_YES;
453         }
454
455         /* Otherwise, we don't know; prepare to recurse */
456         parse_commit_or_die(candidate);
457
458         if (candidate->generation < cutoff)
459                 return CONTAINS_NO;
460
461         return CONTAINS_UNKNOWN;
462 }
463
464 static void push_to_contains_stack(struct commit *candidate, struct contains_stack *contains_stack)
465 {
466         ALLOC_GROW(contains_stack->contains_stack, contains_stack->nr + 1, contains_stack->alloc);
467         contains_stack->contains_stack[contains_stack->nr].commit = candidate;
468         contains_stack->contains_stack[contains_stack->nr++].parents = candidate->parents;
469 }
470
471 static enum contains_result contains_tag_algo(struct commit *candidate,
472                                               const struct commit_list *want,
473                                               struct contains_cache *cache)
474 {
475         struct contains_stack contains_stack = { 0, 0, NULL };
476         enum contains_result result;
477         uint32_t cutoff = GENERATION_NUMBER_INFINITY;
478         const struct commit_list *p;
479
480         for (p = want; p; p = p->next) {
481                 struct commit *c = p->item;
482                 load_commit_graph_info(the_repository, c);
483                 if (c->generation < cutoff)
484                         cutoff = c->generation;
485         }
486
487         result = contains_test(candidate, want, cache, cutoff);
488         if (result != CONTAINS_UNKNOWN)
489                 return result;
490
491         push_to_contains_stack(candidate, &contains_stack);
492         while (contains_stack.nr) {
493                 struct contains_stack_entry *entry = &contains_stack.contains_stack[contains_stack.nr - 1];
494                 struct commit *commit = entry->commit;
495                 struct commit_list *parents = entry->parents;
496
497                 if (!parents) {
498                         *contains_cache_at(cache, commit) = CONTAINS_NO;
499                         contains_stack.nr--;
500                 }
501                 /*
502                  * If we just popped the stack, parents->item has been marked,
503                  * therefore contains_test will return a meaningful yes/no.
504                  */
505                 else switch (contains_test(parents->item, want, cache, cutoff)) {
506                 case CONTAINS_YES:
507                         *contains_cache_at(cache, commit) = CONTAINS_YES;
508                         contains_stack.nr--;
509                         break;
510                 case CONTAINS_NO:
511                         entry->parents = parents->next;
512                         break;
513                 case CONTAINS_UNKNOWN:
514                         push_to_contains_stack(parents->item, &contains_stack);
515                         break;
516                 }
517         }
518         free(contains_stack.contains_stack);
519         return contains_test(candidate, want, cache, cutoff);
520 }
521
522 int commit_contains(struct ref_filter *filter, struct commit *commit,
523                     struct commit_list *list, struct contains_cache *cache)
524 {
525         if (filter->with_commit_tag_algo)
526                 return contains_tag_algo(commit, list, cache) == CONTAINS_YES;
527         return is_descendant_of(commit, list);
528 }
529
530 static int compare_commits_by_gen(const void *_a, const void *_b)
531 {
532         const struct commit *a = *(const struct commit * const *)_a;
533         const struct commit *b = *(const struct commit * const *)_b;
534
535         if (a->generation < b->generation)
536                 return -1;
537         if (a->generation > b->generation)
538                 return 1;
539         return 0;
540 }
541
542 int can_all_from_reach_with_flag(struct object_array *from,
543                                  unsigned int with_flag,
544                                  unsigned int assign_flag,
545                                  time_t min_commit_date,
546                                  uint32_t min_generation)
547 {
548         struct commit **list = NULL;
549         int i;
550         int nr_commits;
551         int result = 1;
552
553         ALLOC_ARRAY(list, from->nr);
554         nr_commits = 0;
555         for (i = 0; i < from->nr; i++) {
556                 struct object *from_one = from->objects[i].item;
557
558                 if (!from_one || from_one->flags & assign_flag)
559                         continue;
560
561                 from_one = deref_tag(the_repository, from_one,
562                                      "a from object", 0);
563                 if (!from_one || from_one->type != OBJ_COMMIT) {
564                         /*
565                          * no way to tell if this is reachable by
566                          * looking at the ancestry chain alone, so
567                          * leave a note to ourselves not to worry about
568                          * this object anymore.
569                          */
570                         from->objects[i].item->flags |= assign_flag;
571                         continue;
572                 }
573
574                 list[nr_commits] = (struct commit *)from_one;
575                 if (parse_commit(list[nr_commits]) ||
576                     list[nr_commits]->generation < min_generation) {
577                         result = 0;
578                         goto cleanup;
579                 }
580
581                 nr_commits++;
582         }
583
584         QSORT(list, nr_commits, compare_commits_by_gen);
585
586         for (i = 0; i < nr_commits; i++) {
587                 /* DFS from list[i] */
588                 struct commit_list *stack = NULL;
589
590                 list[i]->object.flags |= assign_flag;
591                 commit_list_insert(list[i], &stack);
592
593                 while (stack) {
594                         struct commit_list *parent;
595
596                         if (stack->item->object.flags & (with_flag | RESULT)) {
597                                 pop_commit(&stack);
598                                 if (stack)
599                                         stack->item->object.flags |= RESULT;
600                                 continue;
601                         }
602
603                         for (parent = stack->item->parents; parent; parent = parent->next) {
604                                 if (parent->item->object.flags & (with_flag | RESULT))
605                                         stack->item->object.flags |= RESULT;
606
607                                 if (!(parent->item->object.flags & assign_flag)) {
608                                         parent->item->object.flags |= assign_flag;
609
610                                         if (parse_commit(parent->item) ||
611                                             parent->item->date < min_commit_date ||
612                                             parent->item->generation < min_generation)
613                                                 continue;
614
615                                         commit_list_insert(parent->item, &stack);
616                                         break;
617                                 }
618                         }
619
620                         if (!parent)
621                                 pop_commit(&stack);
622                 }
623
624                 if (!(list[i]->object.flags & (with_flag | RESULT))) {
625                         result = 0;
626                         goto cleanup;
627                 }
628         }
629
630 cleanup:
631         clear_commit_marks_many(nr_commits, list, RESULT | assign_flag);
632         free(list);
633
634         for (i = 0; i < from->nr; i++)
635                 from->objects[i].item->flags &= ~assign_flag;
636
637         return result;
638 }
639
640 int can_all_from_reach(struct commit_list *from, struct commit_list *to,
641                        int cutoff_by_min_date)
642 {
643         struct object_array from_objs = OBJECT_ARRAY_INIT;
644         time_t min_commit_date = cutoff_by_min_date ? from->item->date : 0;
645         struct commit_list *from_iter = from, *to_iter = to;
646         int result;
647         uint32_t min_generation = GENERATION_NUMBER_INFINITY;
648
649         while (from_iter) {
650                 add_object_array(&from_iter->item->object, NULL, &from_objs);
651
652                 if (!parse_commit(from_iter->item)) {
653                         if (from_iter->item->date < min_commit_date)
654                                 min_commit_date = from_iter->item->date;
655
656                         if (from_iter->item->generation < min_generation)
657                                 min_generation = from_iter->item->generation;
658                 }
659
660                 from_iter = from_iter->next;
661         }
662
663         while (to_iter) {
664                 if (!parse_commit(to_iter->item)) {
665                         if (to_iter->item->date < min_commit_date)
666                                 min_commit_date = to_iter->item->date;
667
668                         if (to_iter->item->generation < min_generation)
669                                 min_generation = to_iter->item->generation;
670                 }
671
672                 to_iter->item->object.flags |= PARENT2;
673
674                 to_iter = to_iter->next;
675         }
676
677         result = can_all_from_reach_with_flag(&from_objs, PARENT2, PARENT1,
678                                               min_commit_date, min_generation);
679
680         while (from) {
681                 clear_commit_marks(from->item, PARENT1);
682                 from = from->next;
683         }
684
685         while (to) {
686                 clear_commit_marks(to->item, PARENT2);
687                 to = to->next;
688         }
689
690         object_array_clear(&from_objs);
691         return result;
692 }