git.oblomov.eu Git - git/blob - 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 PARENT1         (1u<<16)
  14 #define PARENT2         (1u<<17)
  15 #define STALE           (1u<<18)
  16 #define RESULT          (1u<<19)
  17
  18 static const unsigned all_flags = (PARENT1 | PARENT2 | STALE | RESULT);
  19
  20 static int queue_has_nonstale(struct prio_queue *queue)
  21 {
  22         int i;
  23         for (i = 0; i < queue->nr; i++) {
  24                 struct commit *commit = queue->array[i].data;
  25                 if (!(commit->object.flags & STALE))
  26                         return 1;
  27         }
  28         return 0;
  29 }
  30
  31 /* all input commits in one and twos[] must have been parsed! */
  32 static struct commit_list *paint_down_to_common(struct repository *r,
  33                                                 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 (repo_parse_commit(r, 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 repository *r,
  98                                             struct commit *one, int n,
  99                                             struct commit **twos)
 100 {
 101         struct commit_list *list = NULL;
 102         struct commit_list *result = NULL;
 103         int i;
 104
 105         for (i = 0; i < n; i++) {
 106                 if (one == twos[i])
 107                         /*
 108                          * We do not mark this even with RESULT so we do not
 109                          * have to clean it up.
 110                          */
 111                         return commit_list_insert(one, &result);
 112         }
 113
 114         if (repo_parse_commit(r, one))
 115                 return NULL;
 116         for (i = 0; i < n; i++) {
 117                 if (repo_parse_commit(r, twos[i]))
 118                         return NULL;
 119         }
 120
 121         list = paint_down_to_common(r, one, n, twos, 0);
 122
 123         while (list) {
 124                 struct commit *commit = pop_commit(&list);
 125                 if (!(commit->object.flags & STALE))
 126                         commit_list_insert_by_date(commit, &result);
 127         }
 128         return result;
 129 }
 130
 131 struct commit_list *get_octopus_merge_bases(struct commit_list *in)
 132 {
 133         struct commit_list *i, *j, *k, *ret = NULL;
 134
 135         if (!in)
 136                 return ret;
 137
 138         commit_list_insert(in->item, &ret);
 139
 140         for (i = in->next; i; i = i->next) {
 141                 struct commit_list *new_commits = NULL, *end = NULL;
 142
 143                 for (j = ret; j; j = j->next) {
 144                         struct commit_list *bases;
 145                         bases = get_merge_bases(i->item, j->item);
 146                         if (!new_commits)
 147                                 new_commits = bases;
 148                         else
 149                                 end->next = bases;
 150                         for (k = bases; k; k = k->next)
 151                                 end = k;
 152                 }
 153                 ret = new_commits;
 154         }
 155         return ret;
 156 }
 157
 158 static int remove_redundant(struct repository *r, struct commit **array, int cnt)
 159 {
 160         /*
 161          * Some commit in the array may be an ancestor of
 162          * another commit.  Move such commit to the end of
 163          * the array, and return the number of commits that
 164          * are independent from each other.
 165          */
 166         struct commit **work;
 167         unsigned char *redundant;
 168         int *filled_index;
 169         int i, j, filled;
 170
 171         work = xcalloc(cnt, sizeof(*work));
 172         redundant = xcalloc(cnt, 1);
 173         ALLOC_ARRAY(filled_index, cnt - 1);
 174
 175         for (i = 0; i < cnt; i++)
 176                 repo_parse_commit(r, array[i]);
 177         for (i = 0; i < cnt; i++) {
 178                 struct commit_list *common;
 179                 uint32_t min_generation = array[i]->generation;
 180
 181                 if (redundant[i])
 182                         continue;
 183                 for (j = filled = 0; j < cnt; j++) {
 184                         if (i == j || redundant[j])
 185                                 continue;
 186                         filled_index[filled] = j;
 187                         work[filled++] = array[j];
 188
 189                         if (array[j]->generation < min_generation)
 190                                 min_generation = array[j]->generation;
 191                 }
 192                 common = paint_down_to_common(r, array[i], filled,
 193                                               work, min_generation);
 194                 if (array[i]->object.flags & PARENT2)
 195                         redundant[i] = 1;
 196                 for (j = 0; j < filled; j++)
 197                         if (work[j]->object.flags & PARENT1)
 198                                 redundant[filled_index[j]] = 1;
 199                 clear_commit_marks(array[i], all_flags);
 200                 clear_commit_marks_many(filled, work, all_flags);
 201                 free_commit_list(common);
 202         }
 203
 204         /* Now collect the result */
 205         COPY_ARRAY(work, array, cnt);
 206         for (i = filled = 0; i < cnt; i++)
 207                 if (!redundant[i])
 208                         array[filled++] = work[i];
 209         for (j = filled, i = 0; i < cnt; i++)
 210                 if (redundant[i])
 211                         array[j++] = work[i];
 212         free(work);
 213         free(redundant);
 214         free(filled_index);
 215         return filled;
 216 }
 217
 218 static struct commit_list *get_merge_bases_many_0(struct repository *r,
 219                                                   struct commit *one,
 220                                                   int n,
 221                                                   struct commit **twos,
 222                                                   int cleanup)
 223 {
 224         struct commit_list *list;
 225         struct commit **rslt;
 226         struct commit_list *result;
 227         int cnt, i;
 228
 229         result = merge_bases_many(r, one, n, twos);
 230         for (i = 0; i < n; i++) {
 231                 if (one == twos[i])
 232                         return result;
 233         }
 234         if (!result || !result->next) {
 235                 if (cleanup) {
 236                         clear_commit_marks(one, all_flags);
 237                         clear_commit_marks_many(n, twos, all_flags);
 238                 }
 239                 return result;
 240         }
 241
 242         /* There are more than one */
 243         cnt = commit_list_count(result);
 244         rslt = xcalloc(cnt, sizeof(*rslt));
 245         for (list = result, i = 0; list; list = list->next)
 246                 rslt[i++] = list->item;
 247         free_commit_list(result);
 248
 249         clear_commit_marks(one, all_flags);
 250         clear_commit_marks_many(n, twos, all_flags);
 251
 252         cnt = remove_redundant(r, rslt, cnt);
 253         result = NULL;
 254         for (i = 0; i < cnt; i++)
 255                 commit_list_insert_by_date(rslt[i], &result);
 256         free(rslt);
 257         return result;
 258 }
 259
 260 struct commit_list *repo_get_merge_bases_many(struct repository *r,
 261                                               struct commit *one,
 262                                               int n,
 263                                               struct commit **twos)
 264 {
 265         return get_merge_bases_many_0(r, one, n, twos, 1);
 266 }
 267
 268 struct commit_list *repo_get_merge_bases_many_dirty(struct repository *r,
 269                                                     struct commit *one,
 270                                                     int n,
 271                                                     struct commit **twos)
 272 {
 273         return get_merge_bases_many_0(r, one, n, twos, 0);
 274 }
 275
 276 struct commit_list *repo_get_merge_bases(struct repository *r,
 277                                          struct commit *one,
 278                                          struct commit *two)
 279 {
 280         return get_merge_bases_many_0(r, one, 1, &two, 1);
 281 }
 282
 283 /*
 284  * Is "commit" a descendant of one of the elements on the "with_commit" list?
 285  */
 286 int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
 287 {
 288         if (!with_commit)
 289                 return 1;
 290
 291         if (generation_numbers_enabled(the_repository)) {
 292                 struct commit_list *from_list = NULL;
 293                 int result;
 294                 commit_list_insert(commit, &from_list);
 295                 result = can_all_from_reach(from_list, with_commit, 0);
 296                 free_commit_list(from_list);
 297                 return result;
 298         } else {
 299                 while (with_commit) {
 300                         struct commit *other;
 301
 302                         other = with_commit->item;
 303                         with_commit = with_commit->next;
 304                         if (in_merge_bases(other, commit))
 305                                 return 1;
 306                 }
 307                 return 0;
 308         }
 309 }
 310
 311 /*
 312  * Is "commit" an ancestor of one of the "references"?
 313  */
 314 int repo_in_merge_bases_many(struct repository *r, struct commit *commit,
 315                              int nr_reference, struct commit **reference)
 316 {
 317         struct commit_list *bases;
 318         int ret = 0, i;
 319         uint32_t min_generation = GENERATION_NUMBER_INFINITY;
 320
 321         if (repo_parse_commit(r, commit))
 322                 return ret;
 323         for (i = 0; i < nr_reference; i++) {
 324                 if (repo_parse_commit(r, reference[i]))
 325                         return ret;
 326                 if (reference[i]->generation < min_generation)
 327                         min_generation = reference[i]->generation;
 328         }
 329
 330         if (commit->generation > min_generation)
 331                 return ret;
 332
 333         bases = paint_down_to_common(r, commit,
 334                                      nr_reference, reference,
 335                                      commit->generation);
 336         if (commit->object.flags & PARENT2)
 337                 ret = 1;
 338         clear_commit_marks(commit, all_flags);
 339         clear_commit_marks_many(nr_reference, reference, all_flags);
 340         free_commit_list(bases);
 341         return ret;
 342 }
 343
 344 /*
 345  * Is "commit" an ancestor of (i.e. reachable from) the "reference"?
 346  */
 347 int repo_in_merge_bases(struct repository *r,
 348                         struct commit *commit,
 349                         struct commit *reference)
 350 {
 351         return repo_in_merge_bases_many(r, commit, 1, &reference);
 352 }
 353
 354 struct commit_list *reduce_heads(struct commit_list *heads)
 355 {
 356         struct commit_list *p;
 357         struct commit_list *result = NULL, **tail = &result;
 358         struct commit **array;
 359         int num_head, i;
 360
 361         if (!heads)
 362                 return NULL;
 363
 364         /* Uniquify */
 365         for (p = heads; p; p = p->next)
 366                 p->item->object.flags &= ~STALE;
 367         for (p = heads, num_head = 0; p; p = p->next) {
 368                 if (p->item->object.flags & STALE)
 369                         continue;
 370                 p->item->object.flags |= STALE;
 371                 num_head++;
 372         }
 373         array = xcalloc(num_head, sizeof(*array));
 374         for (p = heads, i = 0; p; p = p->next) {
 375                 if (p->item->object.flags & STALE) {
 376                         array[i++] = p->item;
 377                         p->item->object.flags &= ~STALE;
 378                 }
 379         }
 380         num_head = remove_redundant(the_repository, array, num_head);
 381         for (i = 0; i < num_head; i++)
 382                 tail = &commit_list_insert(array[i], tail)->next;
 383         free(array);
 384         return result;
 385 }
 386
 387 void reduce_heads_replace(struct commit_list **heads)
 388 {
 389         struct commit_list *result = reduce_heads(*heads);
 390         free_commit_list(*heads);
 391         *heads = result;
 392 }
 393
 394 int ref_newer(const struct object_id *new_oid, const struct object_id *old_oid)
 395 {
 396         struct object *o;
 397         struct commit *old_commit, *new_commit;
 398         struct commit_list *old_commit_list = NULL;
 399
 400         /*
 401          * Both new_commit and old_commit must be commit-ish and new_commit is descendant of
 402          * old_commit.  Otherwise we require --force.
 403          */
 404         o = deref_tag(the_repository, parse_object(the_repository, old_oid),
 405                       NULL, 0);
 406         if (!o || o->type != OBJ_COMMIT)
 407                 return 0;
 408         old_commit = (struct commit *) o;
 409
 410         o = deref_tag(the_repository, parse_object(the_repository, new_oid),
 411                       NULL, 0);
 412         if (!o || o->type != OBJ_COMMIT)
 413                 return 0;
 414         new_commit = (struct commit *) o;
 415
 416         if (parse_commit(new_commit) < 0)
 417                 return 0;
 418
 419         commit_list_insert(old_commit, &old_commit_list);
 420         return is_descendant_of(new_commit, old_commit_list);
 421 }
 422
 423 /*
 424  * Mimicking the real stack, this stack lives on the heap, avoiding stack
 425  * overflows.
 426  *
 427  * At each recursion step, the stack items points to the commits whose
 428  * ancestors are to be inspected.
 429  */
 430 struct contains_stack {
 431         int nr, alloc;
 432         struct contains_stack_entry {
 433                 struct commit *commit;
 434                 struct commit_list *parents;
 435         } *contains_stack;
 436 };
 437
 438 static int in_commit_list(const struct commit_list *want, struct commit *c)
 439 {
 440         for (; want; want = want->next)
 441                 if (oideq(&want->item->object.oid, &c->object.oid))
 442                         return 1;
 443         return 0;
 444 }
 445
 446 /*
 447  * Test whether the candidate is contained in the list.
 448  * Do not recurse to find out, though, but return -1 if inconclusive.
 449  */
 450 static enum contains_result contains_test(struct commit *candidate,
 451                                           const struct commit_list *want,
 452                                           struct contains_cache *cache,
 453                                           uint32_t cutoff)
 454 {
 455         enum contains_result *cached = contains_cache_at(cache, candidate);
 456
 457         /* If we already have the answer cached, return that. */
 458         if (*cached)
 459                 return *cached;
 460
 461         /* or are we it? */
 462         if (in_commit_list(want, candidate)) {
 463                 *cached = CONTAINS_YES;
 464                 return CONTAINS_YES;
 465         }
 466
 467         /* Otherwise, we don't know; prepare to recurse */
 468         parse_commit_or_die(candidate);
 469
 470         if (candidate->generation < cutoff)
 471                 return CONTAINS_NO;
 472
 473         return CONTAINS_UNKNOWN;
 474 }
 475
 476 static void push_to_contains_stack(struct commit *candidate, struct contains_stack *contains_stack)
 477 {
 478         ALLOC_GROW(contains_stack->contains_stack, contains_stack->nr + 1, contains_stack->alloc);
 479         contains_stack->contains_stack[contains_stack->nr].commit = candidate;
 480         contains_stack->contains_stack[contains_stack->nr++].parents = candidate->parents;
 481 }
 482
 483 static enum contains_result contains_tag_algo(struct commit *candidate,
 484                                               const struct commit_list *want,
 485                                               struct contains_cache *cache)
 486 {
 487         struct contains_stack contains_stack = { 0, 0, NULL };
 488         enum contains_result result;
 489         uint32_t cutoff = GENERATION_NUMBER_INFINITY;
 490         const struct commit_list *p;
 491
 492         for (p = want; p; p = p->next) {
 493                 struct commit *c = p->item;
 494                 load_commit_graph_info(the_repository, c);
 495                 if (c->generation < cutoff)
 496                         cutoff = c->generation;
 497         }
 498
 499         result = contains_test(candidate, want, cache, cutoff);
 500         if (result != CONTAINS_UNKNOWN)
 501                 return result;
 502
 503         push_to_contains_stack(candidate, &contains_stack);
 504         while (contains_stack.nr) {
 505                 struct contains_stack_entry *entry = &contains_stack.contains_stack[contains_stack.nr - 1];
 506                 struct commit *commit = entry->commit;
 507                 struct commit_list *parents = entry->parents;
 508
 509                 if (!parents) {
 510                         *contains_cache_at(cache, commit) = CONTAINS_NO;
 511                         contains_stack.nr--;
 512                 }
 513                 /*
 514                  * If we just popped the stack, parents->item has been marked,
 515                  * therefore contains_test will return a meaningful yes/no.
 516                  */
 517                 else switch (contains_test(parents->item, want, cache, cutoff)) {
 518                 case CONTAINS_YES:
 519                         *contains_cache_at(cache, commit) = CONTAINS_YES;
 520                         contains_stack.nr--;
 521                         break;
 522                 case CONTAINS_NO:
 523                         entry->parents = parents->next;
 524                         break;
 525                 case CONTAINS_UNKNOWN:
 526                         push_to_contains_stack(parents->item, &contains_stack);
 527                         break;
 528                 }
 529         }
 530         free(contains_stack.contains_stack);
 531         return contains_test(candidate, want, cache, cutoff);
 532 }
 533
 534 int commit_contains(struct ref_filter *filter, struct commit *commit,
 535                     struct commit_list *list, struct contains_cache *cache)
 536 {
 537         if (filter->with_commit_tag_algo)
 538                 return contains_tag_algo(commit, list, cache) == CONTAINS_YES;
 539         return is_descendant_of(commit, list);
 540 }
 541
 542 static int compare_commits_by_gen(const void *_a, const void *_b)
 543 {
 544         const struct commit *a = *(const struct commit * const *)_a;
 545         const struct commit *b = *(const struct commit * const *)_b;
 546
 547         if (a->generation < b->generation)
 548                 return -1;
 549         if (a->generation > b->generation)
 550                 return 1;
 551         return 0;
 552 }
 553
 554 int can_all_from_reach_with_flag(struct object_array *from,
 555                                  unsigned int with_flag,
 556                                  unsigned int assign_flag,
 557                                  time_t min_commit_date,
 558                                  uint32_t min_generation)
 559 {
 560         struct commit **list = NULL;
 561         int i;
 562         int nr_commits;
 563         int result = 1;
 564
 565         ALLOC_ARRAY(list, from->nr);
 566         nr_commits = 0;
 567         for (i = 0; i < from->nr; i++) {
 568                 struct object *from_one = from->objects[i].item;
 569
 570                 if (!from_one || from_one->flags & assign_flag)
 571                         continue;
 572
 573                 from_one = deref_tag(the_repository, from_one,
 574                                      "a from object", 0);
 575                 if (!from_one || from_one->type != OBJ_COMMIT) {
 576                         /*
 577                          * no way to tell if this is reachable by
 578                          * looking at the ancestry chain alone, so
 579                          * leave a note to ourselves not to worry about
 580                          * this object anymore.
 581                          */
 582                         from->objects[i].item->flags |= assign_flag;
 583                         continue;
 584                 }
 585
 586                 list[nr_commits] = (struct commit *)from_one;
 587                 if (parse_commit(list[nr_commits]) ||
 588                     list[nr_commits]->generation < min_generation) {
 589                         result = 0;
 590                         goto cleanup;
 591                 }
 592
 593                 nr_commits++;
 594         }
 595
 596         QSORT(list, nr_commits, compare_commits_by_gen);
 597
 598         for (i = 0; i < nr_commits; i++) {
 599                 /* DFS from list[i] */
 600                 struct commit_list *stack = NULL;
 601
 602                 list[i]->object.flags |= assign_flag;
 603                 commit_list_insert(list[i], &stack);
 604
 605                 while (stack) {
 606                         struct commit_list *parent;
 607
 608                         if (stack->item->object.flags & (with_flag | RESULT)) {
 609                                 pop_commit(&stack);
 610                                 if (stack)
 611                                         stack->item->object.flags |= RESULT;
 612                                 continue;
 613                         }
 614
 615                         for (parent = stack->item->parents; parent; parent = parent->next) {
 616                                 if (parent->item->object.flags & (with_flag | RESULT))
 617                                         stack->item->object.flags |= RESULT;
 618
 619                                 if (!(parent->item->object.flags & assign_flag)) {
 620                                         parent->item->object.flags |= assign_flag;
 621
 622                                         if (parse_commit(parent->item) ||
 623                                             parent->item->date < min_commit_date ||
 624                                             parent->item->generation < min_generation)
 625                                                 continue;
 626
 627                                         commit_list_insert(parent->item, &stack);
 628                                         break;
 629                                 }
 630                         }
 631
 632                         if (!parent)
 633                                 pop_commit(&stack);
 634                 }
 635
 636                 if (!(list[i]->object.flags & (with_flag | RESULT))) {
 637                         result = 0;
 638                         goto cleanup;
 639                 }
 640         }
 641
 642 cleanup:
 643         clear_commit_marks_many(nr_commits, list, RESULT | assign_flag);
 644         free(list);
 645
 646         for (i = 0; i < from->nr; i++)
 647                 from->objects[i].item->flags &= ~assign_flag;
 648
 649         return result;
 650 }
 651
 652 int can_all_from_reach(struct commit_list *from, struct commit_list *to,
 653                        int cutoff_by_min_date)
 654 {
 655         struct object_array from_objs = OBJECT_ARRAY_INIT;
 656         time_t min_commit_date = cutoff_by_min_date ? from->item->date : 0;
 657         struct commit_list *from_iter = from, *to_iter = to;
 658         int result;
 659         uint32_t min_generation = GENERATION_NUMBER_INFINITY;
 660
 661         while (from_iter) {
 662                 add_object_array(&from_iter->item->object, NULL, &from_objs);
 663
 664                 if (!parse_commit(from_iter->item)) {
 665                         if (from_iter->item->date < min_commit_date)
 666                                 min_commit_date = from_iter->item->date;
 667
 668                         if (from_iter->item->generation < min_generation)
 669                                 min_generation = from_iter->item->generation;
 670                 }
 671
 672                 from_iter = from_iter->next;
 673         }
 674
 675         while (to_iter) {
 676                 if (!parse_commit(to_iter->item)) {
 677                         if (to_iter->item->date < min_commit_date)
 678                                 min_commit_date = to_iter->item->date;
 679
 680                         if (to_iter->item->generation < min_generation)
 681                                 min_generation = to_iter->item->generation;
 682                 }
 683
 684                 to_iter->item->object.flags |= PARENT2;
 685
 686                 to_iter = to_iter->next;
 687         }
 688
 689         result = can_all_from_reach_with_flag(&from_objs, PARENT2, PARENT1,
 690                                               min_commit_date, min_generation);
 691
 692         while (from) {
 693                 clear_commit_marks(from->item, PARENT1);
 694                 from = from->next;
 695         }
 696
 697         while (to) {
 698                 clear_commit_marks(to->item, PARENT2);
 699                 to = to->next;
 700         }
 701
 702         object_array_clear(&from_objs);
 703         return result;
 704 }
 705
 706 struct commit_list *get_reachable_subset(struct commit **from, int nr_from,
 707                                          struct commit **to, int nr_to,
 708                                          unsigned int reachable_flag)
 709 {
 710         struct commit **item;
 711         struct commit *current;
 712         struct commit_list *found_commits = NULL;
 713         struct commit **to_last = to + nr_to;
 714         struct commit **from_last = from + nr_from;
 715         uint32_t min_generation = GENERATION_NUMBER_INFINITY;
 716         int num_to_find = 0;
 717
 718         struct prio_queue queue = { compare_commits_by_gen_then_commit_date };
 719
 720         for (item = to; item < to_last; item++) {
 721                 struct commit *c = *item;
 722
 723                 parse_commit(c);
 724                 if (c->generation < min_generation)
 725                         min_generation = c->generation;
 726
 727                 if (!(c->object.flags & PARENT1)) {
 728                         c->object.flags |= PARENT1;
 729                         num_to_find++;
 730                 }
 731         }
 732
 733         for (item = from; item < from_last; item++) {
 734                 struct commit *c = *item;
 735                 if (!(c->object.flags & PARENT2)) {
 736                         c->object.flags |= PARENT2;
 737                         parse_commit(c);
 738
 739                         prio_queue_put(&queue, *item);
 740                 }
 741         }
 742
 743         while (num_to_find && (current = prio_queue_get(&queue)) != NULL) {
 744                 struct commit_list *parents;
 745
 746                 if (current->object.flags & PARENT1) {
 747                         current->object.flags &= ~PARENT1;
 748                         current->object.flags |= reachable_flag;
 749                         commit_list_insert(current, &found_commits);
 750                         num_to_find--;
 751                 }
 752
 753                 for (parents = current->parents; parents; parents = parents->next) {
 754                         struct commit *p = parents->item;
 755
 756                         parse_commit(p);
 757
 758                         if (p->generation < min_generation)
 759                                 continue;
 760
 761                         if (p->object.flags & PARENT2)
 762                                 continue;
 763
 764                         p->object.flags |= PARENT2;
 765                         prio_queue_put(&queue, p);
 766                 }
 767         }
 768
 769         clear_commit_marks_many(nr_to, to, PARENT1);
 770         clear_commit_marks_many(nr_from, from, PARENT2);
 771
 772         return found_commits;
 773 }