commit-reach.c

   1 #include "git-compat-util.h"
   2 #include "commit.h"
   3 #include "commit-graph.h"
   4 #include "decorate.h"
   5 #include "hex.h"
   6 #include "prio-queue.h"
   7 #include "ref-filter.h"
   8 #include "revision.h"
   9 #include "tag.h"
  10 #include "commit-reach.h"
  11 #include "ewah/ewok.h"
  12
  13 /* Remember to update object flag allocation in object.h */
  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 compare_commits_by_gen(const void *_a, const void *_b)
  22 {
  23         const struct commit *a = *(const struct commit * const *)_a;
  24         const struct commit *b = *(const struct commit * const *)_b;
  25
  26         timestamp_t generation_a = commit_graph_generation(a);
  27         timestamp_t generation_b = commit_graph_generation(b);
  28
  29         if (generation_a < generation_b)
  30                 return -1;
  31         if (generation_a > generation_b)
  32                 return 1;
  33         if (a->date < b->date)
  34                 return -1;
  35         if (a->date > b->date)
  36                 return 1;
  37         return 0;
  38 }
  39
  40 static int queue_has_nonstale(struct prio_queue *queue)
  41 {
  42         int i;
  43         for (i = 0; i < queue->nr; i++) {
  44                 struct commit *commit = queue->array[i].data;
  45                 if (!(commit->object.flags & STALE))
  46                         return 1;
  47         }
  48         return 0;
  49 }
  50
  51 /* all input commits in one and twos[] must have been parsed! */
  52 static struct commit_list *paint_down_to_common(struct repository *r,
  53                                                 struct commit *one, int n,
  54                                                 struct commit **twos,
  55                                                 timestamp_t min_generation)
  56 {
  57         struct prio_queue queue = { compare_commits_by_gen_then_commit_date };
  58         struct commit_list *result = NULL;
  59         int i;
  60         timestamp_t last_gen = GENERATION_NUMBER_INFINITY;
  61
  62         if (!min_generation && !corrected_commit_dates_enabled(r))
  63                 queue.compare = compare_commits_by_commit_date;
  64
  65         one->object.flags |= PARENT1;
  66         if (!n) {
  67                 commit_list_append(one, &result);
  68                 return result;
  69         }
  70         prio_queue_put(&queue, one);
  71
  72         for (i = 0; i < n; i++) {
  73                 twos[i]->object.flags |= PARENT2;
  74                 prio_queue_put(&queue, twos[i]);
  75         }
  76
  77         while (queue_has_nonstale(&queue)) {
  78                 struct commit *commit = prio_queue_get(&queue);
  79                 struct commit_list *parents;
  80                 int flags;
  81                 timestamp_t generation = commit_graph_generation(commit);
  82
  83                 if (min_generation && generation > last_gen)
  84                         BUG("bad generation skip %"PRItime" > %"PRItime" at %s",
  85                             generation, last_gen,
  86                             oid_to_hex(&commit->object.oid));
  87                 last_gen = generation;
  88
  89                 if (generation < min_generation)
  90                         break;
  91
  92                 flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
  93                 if (flags == (PARENT1 | PARENT2)) {
  94                         if (!(commit->object.flags & RESULT)) {
  95                                 commit->object.flags |= RESULT;
  96                                 commit_list_insert_by_date(commit, &result);
  97                         }
  98                         /* Mark parents of a found merge stale */
  99                         flags |= STALE;
 100                 }
 101                 parents = commit->parents;
 102                 while (parents) {
 103                         struct commit *p = parents->item;
 104                         parents = parents->next;
 105                         if ((p->object.flags & flags) == flags)
 106                                 continue;
 107                         if (repo_parse_commit(r, p))
 108                                 return NULL;
 109                         p->object.flags |= flags;
 110                         prio_queue_put(&queue, p);
 111                 }
 112         }
 113
 114         clear_prio_queue(&queue);
 115         return result;
 116 }
 117
 118 static struct commit_list *merge_bases_many(struct repository *r,
 119                                             struct commit *one, int n,
 120                                             struct commit **twos)
 121 {
 122         struct commit_list *list = NULL;
 123         struct commit_list *result = NULL;
 124         int i;
 125
 126         for (i = 0; i < n; i++) {
 127                 if (one == twos[i])
 128                         /*
 129                          * We do not mark this even with RESULT so we do not
 130                          * have to clean it up.
 131                          */
 132                         return commit_list_insert(one, &result);
 133         }
 134
 135         if (repo_parse_commit(r, one))
 136                 return NULL;
 137         for (i = 0; i < n; i++) {
 138                 if (repo_parse_commit(r, twos[i]))
 139                         return NULL;
 140         }
 141
 142         list = paint_down_to_common(r, one, n, twos, 0);
 143
 144         while (list) {
 145                 struct commit *commit = pop_commit(&list);
 146                 if (!(commit->object.flags & STALE))
 147                         commit_list_insert_by_date(commit, &result);
 148         }
 149         return result;
 150 }
 151
 152 struct commit_list *get_octopus_merge_bases(struct commit_list *in)
 153 {
 154         struct commit_list *i, *j, *k, *ret = NULL;
 155
 156         if (!in)
 157                 return ret;
 158
 159         commit_list_insert(in->item, &ret);
 160
 161         for (i = in->next; i; i = i->next) {
 162                 struct commit_list *new_commits = NULL, *end = NULL;
 163
 164                 for (j = ret; j; j = j->next) {
 165                         struct commit_list *bases;
 166                         bases = repo_get_merge_bases(the_repository, i->item,
 167                                                      j->item);
 168                         if (!new_commits)
 169                                 new_commits = bases;
 170                         else
 171                                 end->next = bases;
 172                         for (k = bases; k; k = k->next)
 173                                 end = k;
 174                 }
 175                 free_commit_list(ret);
 176                 ret = new_commits;
 177         }
 178         return ret;
 179 }
 180
 181 static int remove_redundant_no_gen(struct repository *r,
 182                                    struct commit **array, int cnt)
 183 {
 184         struct commit **work;
 185         unsigned char *redundant;
 186         int *filled_index;
 187         int i, j, filled;
 188
 189         CALLOC_ARRAY(work, cnt);
 190         redundant = xcalloc(cnt, 1);
 191         ALLOC_ARRAY(filled_index, cnt - 1);
 192
 193         for (i = 0; i < cnt; i++)
 194                 repo_parse_commit(r, array[i]);
 195         for (i = 0; i < cnt; i++) {
 196                 struct commit_list *common;
 197                 timestamp_t min_generation = commit_graph_generation(array[i]);
 198
 199                 if (redundant[i])
 200                         continue;
 201                 for (j = filled = 0; j < cnt; j++) {
 202                         timestamp_t curr_generation;
 203                         if (i == j || redundant[j])
 204                                 continue;
 205                         filled_index[filled] = j;
 206                         work[filled++] = array[j];
 207
 208                         curr_generation = commit_graph_generation(array[j]);
 209                         if (curr_generation < min_generation)
 210                                 min_generation = curr_generation;
 211                 }
 212                 common = paint_down_to_common(r, array[i], filled,
 213                                               work, min_generation);
 214                 if (array[i]->object.flags & PARENT2)
 215                         redundant[i] = 1;
 216                 for (j = 0; j < filled; j++)
 217                         if (work[j]->object.flags & PARENT1)
 218                                 redundant[filled_index[j]] = 1;
 219                 clear_commit_marks(array[i], all_flags);
 220                 clear_commit_marks_many(filled, work, all_flags);
 221                 free_commit_list(common);
 222         }
 223
 224         /* Now collect the result */
 225         COPY_ARRAY(work, array, cnt);
 226         for (i = filled = 0; i < cnt; i++)
 227                 if (!redundant[i])
 228                         array[filled++] = work[i];
 229         free(work);
 230         free(redundant);
 231         free(filled_index);
 232         return filled;
 233 }
 234
 235 static int remove_redundant_with_gen(struct repository *r,
 236                                      struct commit **array, int cnt)
 237 {
 238         int i, count_non_stale = 0, count_still_independent = cnt;
 239         timestamp_t min_generation = GENERATION_NUMBER_INFINITY;
 240         struct commit **walk_start, **sorted;
 241         size_t walk_start_nr = 0, walk_start_alloc = cnt;
 242         int min_gen_pos = 0;
 243
 244         /*
 245          * Sort the input by generation number, ascending. This allows
 246          * us to increase the "min_generation" limit when we discover
 247          * the commit with lowest generation is STALE. The index
 248          * min_gen_pos points to the current position within 'array'
 249          * that is not yet known to be STALE.
 250          */
 251         DUP_ARRAY(sorted, array, cnt);
 252         QSORT(sorted, cnt, compare_commits_by_gen);
 253         min_generation = commit_graph_generation(sorted[0]);
 254
 255         ALLOC_ARRAY(walk_start, walk_start_alloc);
 256
 257         /* Mark all parents of the input as STALE */
 258         for (i = 0; i < cnt; i++) {
 259                 struct commit_list *parents;
 260
 261                 repo_parse_commit(r, array[i]);
 262                 array[i]->object.flags |= RESULT;
 263                 parents = array[i]->parents;
 264
 265                 while (parents) {
 266                         repo_parse_commit(r, parents->item);
 267                         if (!(parents->item->object.flags & STALE)) {
 268                                 parents->item->object.flags |= STALE;
 269                                 ALLOC_GROW(walk_start, walk_start_nr + 1, walk_start_alloc);
 270                                 walk_start[walk_start_nr++] = parents->item;
 271                         }
 272                         parents = parents->next;
 273                 }
 274         }
 275
 276         QSORT(walk_start, walk_start_nr, compare_commits_by_gen);
 277
 278         /* remove STALE bit for now to allow walking through parents */
 279         for (i = 0; i < walk_start_nr; i++)
 280                 walk_start[i]->object.flags &= ~STALE;
 281
 282         /*
 283          * Start walking from the highest generation. Hopefully, it will
 284          * find all other items during the first-parent walk, and we can
 285          * terminate early. Otherwise, we will do the same amount of work
 286          * as before.
 287          */
 288         for (i = walk_start_nr - 1; i >= 0 && count_still_independent > 1; i--) {
 289                 /* push the STALE bits up to min generation */
 290                 struct commit_list *stack = NULL;
 291
 292                 commit_list_insert(walk_start[i], &stack);
 293                 walk_start[i]->object.flags |= STALE;
 294
 295                 while (stack) {
 296                         struct commit_list *parents;
 297                         struct commit *c = stack->item;
 298
 299                         repo_parse_commit(r, c);
 300
 301                         if (c->object.flags & RESULT) {
 302                                 c->object.flags &= ~RESULT;
 303                                 if (--count_still_independent <= 1)
 304                                         break;
 305                                 if (oideq(&c->object.oid, &sorted[min_gen_pos]->object.oid)) {
 306                                         while (min_gen_pos < cnt - 1 &&
 307                                                (sorted[min_gen_pos]->object.flags & STALE))
 308                                                 min_gen_pos++;
 309                                         min_generation = commit_graph_generation(sorted[min_gen_pos]);
 310                                 }
 311                         }
 312
 313                         if (commit_graph_generation(c) < min_generation) {
 314                                 pop_commit(&stack);
 315                                 continue;
 316                         }
 317
 318                         parents = c->parents;
 319                         while (parents) {
 320                                 if (!(parents->item->object.flags & STALE)) {
 321                                         parents->item->object.flags |= STALE;
 322                                         commit_list_insert(parents->item, &stack);
 323                                         break;
 324                                 }
 325                                 parents = parents->next;
 326                         }
 327
 328                         /* pop if all parents have been visited already */
 329                         if (!parents)
 330                                 pop_commit(&stack);
 331                 }
 332                 free_commit_list(stack);
 333         }
 334         free(sorted);
 335
 336         /* clear result */
 337         for (i = 0; i < cnt; i++)
 338                 array[i]->object.flags &= ~RESULT;
 339
 340         /* rearrange array */
 341         for (i = count_non_stale = 0; i < cnt; i++) {
 342                 if (!(array[i]->object.flags & STALE))
 343                         array[count_non_stale++] = array[i];
 344         }
 345
 346         /* clear marks */
 347         clear_commit_marks_many(walk_start_nr, walk_start, STALE);
 348         free(walk_start);
 349
 350         return count_non_stale;
 351 }
 352
 353 static int remove_redundant(struct repository *r, struct commit **array, int cnt)
 354 {
 355         /*
 356          * Some commit in the array may be an ancestor of
 357          * another commit.  Move the independent commits to the
 358          * beginning of 'array' and return their number. Callers
 359          * should not rely upon the contents of 'array' after
 360          * that number.
 361          */
 362         if (generation_numbers_enabled(r)) {
 363                 int i;
 364
 365                 /*
 366                  * If we have a single commit with finite generation
 367                  * number, then the _with_gen algorithm is preferred.
 368                  */
 369                 for (i = 0; i < cnt; i++) {
 370                         if (commit_graph_generation(array[i]) < GENERATION_NUMBER_INFINITY)
 371                                 return remove_redundant_with_gen(r, array, cnt);
 372                 }
 373         }
 374
 375         return remove_redundant_no_gen(r, array, cnt);
 376 }
 377
 378 static struct commit_list *get_merge_bases_many_0(struct repository *r,
 379                                                   struct commit *one,
 380                                                   int n,
 381                                                   struct commit **twos,
 382                                                   int cleanup)
 383 {
 384         struct commit_list *list;
 385         struct commit **rslt;
 386         struct commit_list *result;
 387         int cnt, i;
 388
 389         result = merge_bases_many(r, one, n, twos);
 390         for (i = 0; i < n; i++) {
 391                 if (one == twos[i])
 392                         return result;
 393         }
 394         if (!result || !result->next) {
 395                 if (cleanup) {
 396                         clear_commit_marks(one, all_flags);
 397                         clear_commit_marks_many(n, twos, all_flags);
 398                 }
 399                 return result;
 400         }
 401
 402         /* There are more than one */
 403         cnt = commit_list_count(result);
 404         CALLOC_ARRAY(rslt, cnt);
 405         for (list = result, i = 0; list; list = list->next)
 406                 rslt[i++] = list->item;
 407         free_commit_list(result);
 408
 409         clear_commit_marks(one, all_flags);
 410         clear_commit_marks_many(n, twos, all_flags);
 411
 412         cnt = remove_redundant(r, rslt, cnt);
 413         result = NULL;
 414         for (i = 0; i < cnt; i++)
 415                 commit_list_insert_by_date(rslt[i], &result);
 416         free(rslt);
 417         return result;
 418 }
 419
 420 struct commit_list *repo_get_merge_bases_many(struct repository *r,
 421                                               struct commit *one,
 422                                               int n,
 423                                               struct commit **twos)
 424 {
 425         return get_merge_bases_many_0(r, one, n, twos, 1);
 426 }
 427
 428 struct commit_list *repo_get_merge_bases_many_dirty(struct repository *r,
 429                                                     struct commit *one,
 430                                                     int n,
 431                                                     struct commit **twos)
 432 {
 433         return get_merge_bases_many_0(r, one, n, twos, 0);
 434 }
 435
 436 struct commit_list *repo_get_merge_bases(struct repository *r,
 437                                          struct commit *one,
 438                                          struct commit *two)
 439 {
 440         return get_merge_bases_many_0(r, one, 1, &two, 1);
 441 }
 442
 443 /*
 444  * Is "commit" a descendant of one of the elements on the "with_commit" list?
 445  */
 446 int repo_is_descendant_of(struct repository *r,
 447                           struct commit *commit,
 448                           struct commit_list *with_commit)
 449 {
 450         if (!with_commit)
 451                 return 1;
 452
 453         if (generation_numbers_enabled(r)) {
 454                 struct commit_list *from_list = NULL;
 455                 int result;
 456                 commit_list_insert(commit, &from_list);
 457                 result = can_all_from_reach(from_list, with_commit, 0);
 458                 free_commit_list(from_list);
 459                 return result;
 460         } else {
 461                 while (with_commit) {
 462                         struct commit *other;
 463
 464                         other = with_commit->item;
 465                         with_commit = with_commit->next;
 466                         if (repo_in_merge_bases_many(r, other, 1, &commit))
 467                                 return 1;
 468                 }
 469                 return 0;
 470         }
 471 }
 472
 473 /*
 474  * Is "commit" an ancestor of one of the "references"?
 475  */
 476 int repo_in_merge_bases_many(struct repository *r, struct commit *commit,
 477                              int nr_reference, struct commit **reference)
 478 {
 479         struct commit_list *bases;
 480         int ret = 0, i;
 481         timestamp_t generation, max_generation = GENERATION_NUMBER_ZERO;
 482
 483         if (repo_parse_commit(r, commit))
 484                 return ret;
 485         for (i = 0; i < nr_reference; i++) {
 486                 if (repo_parse_commit(r, reference[i]))
 487                         return ret;
 488
 489                 generation = commit_graph_generation(reference[i]);
 490                 if (generation > max_generation)
 491                         max_generation = generation;
 492         }
 493
 494         generation = commit_graph_generation(commit);
 495         if (generation > max_generation)
 496                 return ret;
 497
 498         bases = paint_down_to_common(r, commit,
 499                                      nr_reference, reference,
 500                                      generation);
 501         if (commit->object.flags & PARENT2)
 502                 ret = 1;
 503         clear_commit_marks(commit, all_flags);
 504         clear_commit_marks_many(nr_reference, reference, all_flags);
 505         free_commit_list(bases);
 506         return ret;
 507 }
 508
 509 /*
 510  * Is "commit" an ancestor of (i.e. reachable from) the "reference"?
 511  */
 512 int repo_in_merge_bases(struct repository *r,
 513                         struct commit *commit,
 514                         struct commit *reference)
 515 {
 516         int res;
 517         struct commit_list *list = NULL;
 518         struct commit_list **next = &list;
 519
 520         next = commit_list_append(commit, next);
 521         res = repo_is_descendant_of(r, reference, list);
 522         free_commit_list(list);
 523
 524         return res;
 525 }
 526
 527 struct commit_list *reduce_heads(struct commit_list *heads)
 528 {
 529         struct commit_list *p;
 530         struct commit_list *result = NULL, **tail = &result;
 531         struct commit **array;
 532         int num_head, i;
 533
 534         if (!heads)
 535                 return NULL;
 536
 537         /* Uniquify */
 538         for (p = heads; p; p = p->next)
 539                 p->item->object.flags &= ~STALE;
 540         for (p = heads, num_head = 0; p; p = p->next) {
 541                 if (p->item->object.flags & STALE)
 542                         continue;
 543                 p->item->object.flags |= STALE;
 544                 num_head++;
 545         }
 546         CALLOC_ARRAY(array, num_head);
 547         for (p = heads, i = 0; p; p = p->next) {
 548                 if (p->item->object.flags & STALE) {
 549                         array[i++] = p->item;
 550                         p->item->object.flags &= ~STALE;
 551                 }
 552         }
 553         num_head = remove_redundant(the_repository, array, num_head);
 554         for (i = 0; i < num_head; i++)
 555                 tail = &commit_list_insert(array[i], tail)->next;
 556         free(array);
 557         return result;
 558 }
 559
 560 void reduce_heads_replace(struct commit_list **heads)
 561 {
 562         struct commit_list *result = reduce_heads(*heads);
 563         free_commit_list(*heads);
 564         *heads = result;
 565 }
 566
 567 int ref_newer(const struct object_id *new_oid, const struct object_id *old_oid)
 568 {
 569         struct object *o;
 570         struct commit *old_commit, *new_commit;
 571         struct commit_list *old_commit_list = NULL;
 572         int ret;
 573
 574         /*
 575          * Both new_commit and old_commit must be commit-ish and new_commit is descendant of
 576          * old_commit.  Otherwise we require --force.
 577          */
 578         o = deref_tag(the_repository, parse_object(the_repository, old_oid),
 579                       NULL, 0);
 580         if (!o || o->type != OBJ_COMMIT)
 581                 return 0;
 582         old_commit = (struct commit *) o;
 583
 584         o = deref_tag(the_repository, parse_object(the_repository, new_oid),
 585                       NULL, 0);
 586         if (!o || o->type != OBJ_COMMIT)
 587                 return 0;
 588         new_commit = (struct commit *) o;
 589
 590         if (repo_parse_commit(the_repository, new_commit) < 0)
 591                 return 0;
 592
 593         commit_list_insert(old_commit, &old_commit_list);
 594         ret = repo_is_descendant_of(the_repository,
 595                                     new_commit, old_commit_list);
 596         free_commit_list(old_commit_list);
 597         return ret;
 598 }
 599
 600 /*
 601  * Mimicking the real stack, this stack lives on the heap, avoiding stack
 602  * overflows.
 603  *
 604  * At each recursion step, the stack items points to the commits whose
 605  * ancestors are to be inspected.
 606  */
 607 struct contains_stack {
 608         int nr, alloc;
 609         struct contains_stack_entry {
 610                 struct commit *commit;
 611                 struct commit_list *parents;
 612         } *contains_stack;
 613 };
 614
 615 static int in_commit_list(const struct commit_list *want, struct commit *c)
 616 {
 617         for (; want; want = want->next)
 618                 if (oideq(&want->item->object.oid, &c->object.oid))
 619                         return 1;
 620         return 0;
 621 }
 622
 623 /*
 624  * Test whether the candidate is contained in the list.
 625  * Do not recurse to find out, though, but return -1 if inconclusive.
 626  */
 627 static enum contains_result contains_test(struct commit *candidate,
 628                                           const struct commit_list *want,
 629                                           struct contains_cache *cache,
 630                                           timestamp_t cutoff)
 631 {
 632         enum contains_result *cached = contains_cache_at(cache, candidate);
 633
 634         /* If we already have the answer cached, return that. */
 635         if (*cached)
 636                 return *cached;
 637
 638         /* or are we it? */
 639         if (in_commit_list(want, candidate)) {
 640                 *cached = CONTAINS_YES;
 641                 return CONTAINS_YES;
 642         }
 643
 644         /* Otherwise, we don't know; prepare to recurse */
 645         parse_commit_or_die(candidate);
 646
 647         if (commit_graph_generation(candidate) < cutoff)
 648                 return CONTAINS_NO;
 649
 650         return CONTAINS_UNKNOWN;
 651 }
 652
 653 static void push_to_contains_stack(struct commit *candidate, struct contains_stack *contains_stack)
 654 {
 655         ALLOC_GROW(contains_stack->contains_stack, contains_stack->nr + 1, contains_stack->alloc);
 656         contains_stack->contains_stack[contains_stack->nr].commit = candidate;
 657         contains_stack->contains_stack[contains_stack->nr++].parents = candidate->parents;
 658 }
 659
 660 static enum contains_result contains_tag_algo(struct commit *candidate,
 661                                               const struct commit_list *want,
 662                                               struct contains_cache *cache)
 663 {
 664         struct contains_stack contains_stack = { 0, 0, NULL };
 665         enum contains_result result;
 666         timestamp_t cutoff = GENERATION_NUMBER_INFINITY;
 667         const struct commit_list *p;
 668
 669         for (p = want; p; p = p->next) {
 670                 timestamp_t generation;
 671                 struct commit *c = p->item;
 672                 load_commit_graph_info(the_repository, c);
 673                 generation = commit_graph_generation(c);
 674                 if (generation < cutoff)
 675                         cutoff = generation;
 676         }
 677
 678         result = contains_test(candidate, want, cache, cutoff);
 679         if (result != CONTAINS_UNKNOWN)
 680                 return result;
 681
 682         push_to_contains_stack(candidate, &contains_stack);
 683         while (contains_stack.nr) {
 684                 struct contains_stack_entry *entry = &contains_stack.contains_stack[contains_stack.nr - 1];
 685                 struct commit *commit = entry->commit;
 686                 struct commit_list *parents = entry->parents;
 687
 688                 if (!parents) {
 689                         *contains_cache_at(cache, commit) = CONTAINS_NO;
 690                         contains_stack.nr--;
 691                 }
 692                 /*
 693                  * If we just popped the stack, parents->item has been marked,
 694                  * therefore contains_test will return a meaningful yes/no.
 695                  */
 696                 else switch (contains_test(parents->item, want, cache, cutoff)) {
 697                 case CONTAINS_YES:
 698                         *contains_cache_at(cache, commit) = CONTAINS_YES;
 699                         contains_stack.nr--;
 700                         break;
 701                 case CONTAINS_NO:
 702                         entry->parents = parents->next;
 703                         break;
 704                 case CONTAINS_UNKNOWN:
 705                         push_to_contains_stack(parents->item, &contains_stack);
 706                         break;
 707                 }
 708         }
 709         free(contains_stack.contains_stack);
 710         return contains_test(candidate, want, cache, cutoff);
 711 }
 712
 713 int commit_contains(struct ref_filter *filter, struct commit *commit,
 714                     struct commit_list *list, struct contains_cache *cache)
 715 {
 716         if (filter->with_commit_tag_algo)
 717                 return contains_tag_algo(commit, list, cache) == CONTAINS_YES;
 718         return repo_is_descendant_of(the_repository, commit, list);
 719 }
 720
 721 int can_all_from_reach_with_flag(struct object_array *from,
 722                                  unsigned int with_flag,
 723                                  unsigned int assign_flag,
 724                                  time_t min_commit_date,
 725                                  timestamp_t min_generation)
 726 {
 727         struct commit **list = NULL;
 728         int i;
 729         int nr_commits;
 730         int result = 1;
 731
 732         ALLOC_ARRAY(list, from->nr);
 733         nr_commits = 0;
 734         for (i = 0; i < from->nr; i++) {
 735                 struct object *from_one = from->objects[i].item;
 736
 737                 if (!from_one || from_one->flags & assign_flag)
 738                         continue;
 739
 740                 from_one = deref_tag(the_repository, from_one,
 741                                      "a from object", 0);
 742                 if (!from_one || from_one->type != OBJ_COMMIT) {
 743                         /*
 744                          * no way to tell if this is reachable by
 745                          * looking at the ancestry chain alone, so
 746                          * leave a note to ourselves not to worry about
 747                          * this object anymore.
 748                          */
 749                         from->objects[i].item->flags |= assign_flag;
 750                         continue;
 751                 }
 752
 753                 list[nr_commits] = (struct commit *)from_one;
 754                 if (repo_parse_commit(the_repository, list[nr_commits]) ||
 755                     commit_graph_generation(list[nr_commits]) < min_generation) {
 756                         result = 0;
 757                         goto cleanup;
 758                 }
 759
 760                 nr_commits++;
 761         }
 762
 763         QSORT(list, nr_commits, compare_commits_by_gen);
 764
 765         for (i = 0; i < nr_commits; i++) {
 766                 /* DFS from list[i] */
 767                 struct commit_list *stack = NULL;
 768
 769                 list[i]->object.flags |= assign_flag;
 770                 commit_list_insert(list[i], &stack);
 771
 772                 while (stack) {
 773                         struct commit_list *parent;
 774
 775                         if (stack->item->object.flags & (with_flag | RESULT)) {
 776                                 pop_commit(&stack);
 777                                 if (stack)
 778                                         stack->item->object.flags |= RESULT;
 779                                 continue;
 780                         }
 781
 782                         for (parent = stack->item->parents; parent; parent = parent->next) {
 783                                 if (parent->item->object.flags & (with_flag | RESULT))
 784                                         stack->item->object.flags |= RESULT;
 785
 786                                 if (!(parent->item->object.flags & assign_flag)) {
 787                                         parent->item->object.flags |= assign_flag;
 788
 789                                         if (repo_parse_commit(the_repository, parent->item) ||
 790                                             parent->item->date < min_commit_date ||
 791                                             commit_graph_generation(parent->item) < min_generation)
 792                                                 continue;
 793
 794                                         commit_list_insert(parent->item, &stack);
 795                                         break;
 796                                 }
 797                         }
 798
 799                         if (!parent)
 800                                 pop_commit(&stack);
 801                 }
 802
 803                 if (!(list[i]->object.flags & (with_flag | RESULT))) {
 804                         result = 0;
 805                         goto cleanup;
 806                 }
 807         }
 808
 809 cleanup:
 810         clear_commit_marks_many(nr_commits, list, RESULT | assign_flag);
 811         free(list);
 812
 813         for (i = 0; i < from->nr; i++) {
 814                 struct object *from_one = from->objects[i].item;
 815
 816                 if (from_one)
 817                         from_one->flags &= ~assign_flag;
 818         }
 819
 820         return result;
 821 }
 822
 823 int can_all_from_reach(struct commit_list *from, struct commit_list *to,
 824                        int cutoff_by_min_date)
 825 {
 826         struct object_array from_objs = OBJECT_ARRAY_INIT;
 827         time_t min_commit_date = cutoff_by_min_date ? from->item->date : 0;
 828         struct commit_list *from_iter = from, *to_iter = to;
 829         int result;
 830         timestamp_t min_generation = GENERATION_NUMBER_INFINITY;
 831
 832         while (from_iter) {
 833                 add_object_array(&from_iter->item->object, NULL, &from_objs);
 834
 835                 if (!repo_parse_commit(the_repository, from_iter->item)) {
 836                         timestamp_t generation;
 837                         if (from_iter->item->date < min_commit_date)
 838                                 min_commit_date = from_iter->item->date;
 839
 840                         generation = commit_graph_generation(from_iter->item);
 841                         if (generation < min_generation)
 842                                 min_generation = generation;
 843                 }
 844
 845                 from_iter = from_iter->next;
 846         }
 847
 848         while (to_iter) {
 849                 if (!repo_parse_commit(the_repository, to_iter->item)) {
 850                         timestamp_t generation;
 851                         if (to_iter->item->date < min_commit_date)
 852                                 min_commit_date = to_iter->item->date;
 853
 854                         generation = commit_graph_generation(to_iter->item);
 855                         if (generation < min_generation)
 856                                 min_generation = generation;
 857                 }
 858
 859                 to_iter->item->object.flags |= PARENT2;
 860
 861                 to_iter = to_iter->next;
 862         }
 863
 864         result = can_all_from_reach_with_flag(&from_objs, PARENT2, PARENT1,
 865                                               min_commit_date, min_generation);
 866
 867         while (from) {
 868                 clear_commit_marks(from->item, PARENT1);
 869                 from = from->next;
 870         }
 871
 872         while (to) {
 873                 clear_commit_marks(to->item, PARENT2);
 874                 to = to->next;
 875         }
 876
 877         object_array_clear(&from_objs);
 878         return result;
 879 }
 880
 881 struct commit_list *get_reachable_subset(struct commit **from, int nr_from,
 882                                          struct commit **to, int nr_to,
 883                                          unsigned int reachable_flag)
 884 {
 885         struct commit **item;
 886         struct commit *current;
 887         struct commit_list *found_commits = NULL;
 888         struct commit **to_last = to + nr_to;
 889         struct commit **from_last = from + nr_from;
 890         timestamp_t min_generation = GENERATION_NUMBER_INFINITY;
 891         int num_to_find = 0;
 892
 893         struct prio_queue queue = { compare_commits_by_gen_then_commit_date };
 894
 895         for (item = to; item < to_last; item++) {
 896                 timestamp_t generation;
 897                 struct commit *c = *item;
 898
 899                 repo_parse_commit(the_repository, c);
 900                 generation = commit_graph_generation(c);
 901                 if (generation < min_generation)
 902                         min_generation = generation;
 903
 904                 if (!(c->object.flags & PARENT1)) {
 905                         c->object.flags |= PARENT1;
 906                         num_to_find++;
 907                 }
 908         }
 909
 910         for (item = from; item < from_last; item++) {
 911                 struct commit *c = *item;
 912                 if (!(c->object.flags & PARENT2)) {
 913                         c->object.flags |= PARENT2;
 914                         repo_parse_commit(the_repository, c);
 915
 916                         prio_queue_put(&queue, *item);
 917                 }
 918         }
 919
 920         while (num_to_find && (current = prio_queue_get(&queue)) != NULL) {
 921                 struct commit_list *parents;
 922
 923                 if (current->object.flags & PARENT1) {
 924                         current->object.flags &= ~PARENT1;
 925                         current->object.flags |= reachable_flag;
 926                         commit_list_insert(current, &found_commits);
 927                         num_to_find--;
 928                 }
 929
 930                 for (parents = current->parents; parents; parents = parents->next) {
 931                         struct commit *p = parents->item;
 932
 933                         repo_parse_commit(the_repository, p);
 934
 935                         if (commit_graph_generation(p) < min_generation)
 936                                 continue;
 937
 938                         if (p->object.flags & PARENT2)
 939                                 continue;
 940
 941                         p->object.flags |= PARENT2;
 942                         prio_queue_put(&queue, p);
 943                 }
 944         }
 945
 946         clear_prio_queue(&queue);
 947
 948         clear_commit_marks_many(nr_to, to, PARENT1);
 949         clear_commit_marks_many(nr_from, from, PARENT2);
 950
 951         return found_commits;
 952 }
 953
 954 define_commit_slab(bit_arrays, struct bitmap *);
 955 static struct bit_arrays bit_arrays;
 956
 957 static void insert_no_dup(struct prio_queue *queue, struct commit *c)
 958 {
 959         if (c->object.flags & PARENT2)
 960                 return;
 961         prio_queue_put(queue, c);
 962         c->object.flags |= PARENT2;
 963 }
 964
 965 static struct bitmap *get_bit_array(struct commit *c, int width)
 966 {
 967         struct bitmap **bitmap = bit_arrays_at(&bit_arrays, c);
 968         if (!*bitmap)
 969                 *bitmap = bitmap_word_alloc(width);
 970         return *bitmap;
 971 }
 972
 973 static void free_bit_array(struct commit *c)
 974 {
 975         struct bitmap **bitmap = bit_arrays_at(&bit_arrays, c);
 976         if (!*bitmap)
 977                 return;
 978         bitmap_free(*bitmap);
 979         *bitmap = NULL;
 980 }
 981
 982 void ahead_behind(struct repository *r,
 983                   struct commit **commits, size_t commits_nr,
 984                   struct ahead_behind_count *counts, size_t counts_nr)
 985 {
 986         struct prio_queue queue = { .compare = compare_commits_by_gen_then_commit_date };
 987         size_t width = DIV_ROUND_UP(commits_nr, BITS_IN_EWORD);
 988
 989         if (!commits_nr || !counts_nr)
 990                 return;
 991
 992         for (size_t i = 0; i < counts_nr; i++) {
 993                 counts[i].ahead = 0;
 994                 counts[i].behind = 0;
 995         }
 996
 997         ensure_generations_valid(r, commits, commits_nr);
 998
 999         init_bit_arrays(&bit_arrays);
1000
1001         for (size_t i = 0; i < commits_nr; i++) {
1002                 struct commit *c = commits[i];
1003                 struct bitmap *bitmap = get_bit_array(c, width);
1004
1005                 bitmap_set(bitmap, i);
1006                 insert_no_dup(&queue, c);
1007         }
1008
1009         while (queue_has_nonstale(&queue)) {
1010                 struct commit *c = prio_queue_get(&queue);
1011                 struct commit_list *p;
1012                 struct bitmap *bitmap_c = get_bit_array(c, width);
1013
1014                 for (size_t i = 0; i < counts_nr; i++) {
1015                         int reach_from_tip = !!bitmap_get(bitmap_c, counts[i].tip_index);
1016                         int reach_from_base = !!bitmap_get(bitmap_c, counts[i].base_index);
1017
1018                         if (reach_from_tip ^ reach_from_base) {
1019                                 if (reach_from_base)
1020                                         counts[i].behind++;
1021                                 else
1022                                         counts[i].ahead++;
1023                         }
1024                 }
1025
1026                 for (p = c->parents; p; p = p->next) {
1027                         struct bitmap *bitmap_p;
1028
1029                         repo_parse_commit(r, p->item);
1030
1031                         bitmap_p = get_bit_array(p->item, width);
1032                         bitmap_or(bitmap_p, bitmap_c);
1033
1034                         /*
1035                          * If this parent is reachable from every starting
1036                          * commit, then none of its ancestors can contribute
1037                          * to the ahead/behind count. Mark it as STALE, so
1038                          * we can stop the walk when every commit in the
1039                          * queue is STALE.
1040                          */
1041                         if (bitmap_popcount(bitmap_p) == commits_nr)
1042                                 p->item->object.flags |= STALE;
1043
1044                         insert_no_dup(&queue, p->item);
1045                 }
1046
1047                 free_bit_array(c);
1048         }
1049
1050         /* STALE is used here, PARENT2 is used by insert_no_dup(). */
1051         repo_clear_commit_marks(r, PARENT2 | STALE);
1052         clear_bit_arrays(&bit_arrays);
1053         clear_prio_queue(&queue);
1054 }
1055
1056 struct commit_and_index {
1057         struct commit *commit;
1058         unsigned int index;
1059         timestamp_t generation;
1060 };
1061
1062 static int compare_commit_and_index_by_generation(const void *va, const void *vb)
1063 {
1064         const struct commit_and_index *a = (const struct commit_and_index *)va;
1065         const struct commit_and_index *b = (const struct commit_and_index *)vb;
1066
1067         if (a->generation > b->generation)
1068                 return 1;
1069         if (a->generation < b->generation)
1070                 return -1;
1071         return 0;
1072 }
1073
1074 void tips_reachable_from_bases(struct repository *r,
1075                                struct commit_list *bases,
1076                                struct commit **tips, size_t tips_nr,
1077                                int mark)
1078 {
1079         struct commit_and_index *commits;
1080         size_t min_generation_index = 0;
1081         timestamp_t min_generation;
1082         struct commit_list *stack = NULL;
1083
1084         if (!bases || !tips || !tips_nr)
1085                 return;
1086
1087         /*
1088          * Do a depth-first search starting at 'bases' to search for the
1089          * tips. Stop at the lowest (un-found) generation number. When
1090          * finding the lowest commit, increase the minimum generation
1091          * number to the next lowest (un-found) generation number.
1092          */
1093
1094         CALLOC_ARRAY(commits, tips_nr);
1095
1096         for (size_t i = 0; i < tips_nr; i++) {
1097                 commits[i].commit = tips[i];
1098                 commits[i].index = i;
1099                 commits[i].generation = commit_graph_generation(tips[i]);
1100         }
1101
1102         /* Sort with generation number ascending. */
1103         QSORT(commits, tips_nr, compare_commit_and_index_by_generation);
1104         min_generation = commits[0].generation;
1105
1106         while (bases) {
1107                 repo_parse_commit(r, bases->item);
1108                 commit_list_insert(bases->item, &stack);
1109                 bases = bases->next;
1110         }
1111
1112         while (stack) {
1113                 int explored_all_parents = 1;
1114                 struct commit_list *p;
1115                 struct commit *c = stack->item;
1116                 timestamp_t c_gen = commit_graph_generation(c);
1117
1118                 /* Does it match any of our tips? */
1119                 for (size_t j = min_generation_index; j < tips_nr; j++) {
1120                         if (c_gen < commits[j].generation)
1121                                 break;
1122
1123                         if (commits[j].commit == c) {
1124                                 tips[commits[j].index]->object.flags |= mark;
1125
1126                                 if (j == min_generation_index) {
1127                                         unsigned int k = j + 1;
1128                                         while (k < tips_nr &&
1129                                                (tips[commits[k].index]->object.flags & mark))
1130                                                 k++;
1131
1132                                         /* Terminate early if all found. */
1133                                         if (k >= tips_nr)
1134                                                 goto done;
1135
1136                                         min_generation_index = k;
1137                                         min_generation = commits[k].generation;
1138                                 }
1139                         }
1140                 }
1141
1142                 for (p = c->parents; p; p = p->next) {
1143                         repo_parse_commit(r, p->item);
1144
1145                         /* Have we already explored this parent? */
1146                         if (p->item->object.flags & SEEN)
1147                                 continue;
1148
1149                         /* Is it below the current minimum generation? */
1150                         if (commit_graph_generation(p->item) < min_generation)
1151                                 continue;
1152
1153                         /* Ok, we will explore from here on. */
1154                         p->item->object.flags |= SEEN;
1155                         explored_all_parents = 0;
1156                         commit_list_insert(p->item, &stack);
1157                         break;
1158                 }
1159
1160                 if (explored_all_parents)
1161                         pop_commit(&stack);
1162         }
1163
1164 done:
1165         free(commits);
1166         repo_clear_commit_marks(r, SEEN);
1167 }