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 compare_commits_by_gen(const void *_a, const void *_b)
  21 {
  22         const struct commit *a = *(const struct commit * const *)_a;
  23         const struct commit *b = *(const struct commit * const *)_b;
  24
  25         timestamp_t generation_a = commit_graph_generation(a);
  26         timestamp_t generation_b = commit_graph_generation(b);
  27
  28         if (generation_a < generation_b)
  29                 return -1;
  30         if (generation_a > generation_b)
  31                 return 1;
  32         if (a->date < b->date)
  33                 return -1;
  34         if (a->date > b->date)
  35                 return 1;
  36         return 0;
  37 }
  38
  39 static int queue_has_nonstale(struct prio_queue *queue)
  40 {
  41         int i;
  42         for (i = 0; i < queue->nr; i++) {
  43                 struct commit *commit = queue->array[i].data;
  44                 if (!(commit->object.flags & STALE))
  45                         return 1;
  46         }
  47         return 0;
  48 }
  49
  50 /* all input commits in one and twos[] must have been parsed! */
  51 static struct commit_list *paint_down_to_common(struct repository *r,
  52                                                 struct commit *one, int n,
  53                                                 struct commit **twos,
  54                                                 timestamp_t min_generation)
  55 {
  56         struct prio_queue queue = { compare_commits_by_gen_then_commit_date };
  57         struct commit_list *result = NULL;
  58         int i;
  59         timestamp_t last_gen = GENERATION_NUMBER_INFINITY;
  60
  61         if (!min_generation && !corrected_commit_dates_enabled(r))
  62                 queue.compare = compare_commits_by_commit_date;
  63
  64         one->object.flags |= PARENT1;
  65         if (!n) {
  66                 commit_list_append(one, &result);
  67                 return result;
  68         }
  69         prio_queue_put(&queue, one);
  70
  71         for (i = 0; i < n; i++) {
  72                 twos[i]->object.flags |= PARENT2;
  73                 prio_queue_put(&queue, twos[i]);
  74         }
  75
  76         while (queue_has_nonstale(&queue)) {
  77                 struct commit *commit = prio_queue_get(&queue);
  78                 struct commit_list *parents;
  79                 int flags;
  80                 timestamp_t generation = commit_graph_generation(commit);
  81
  82                 if (min_generation && generation > last_gen)
  83                         BUG("bad generation skip %"PRItime" > %"PRItime" at %s",
  84                             generation, last_gen,
  85                             oid_to_hex(&commit->object.oid));
  86                 last_gen = generation;
  87
  88                 if (generation < min_generation)
  89                         break;
  90
  91                 flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
  92                 if (flags == (PARENT1 | PARENT2)) {
  93                         if (!(commit->object.flags & RESULT)) {
  94                                 commit->object.flags |= RESULT;
  95                                 commit_list_insert_by_date(commit, &result);
  96                         }
  97                         /* Mark parents of a found merge stale */
  98                         flags |= STALE;
  99                 }
 100                 parents = commit->parents;
 101                 while (parents) {
 102                         struct commit *p = parents->item;
 103                         parents = parents->next;
 104                         if ((p->object.flags & flags) == flags)
 105                                 continue;
 106                         if (repo_parse_commit(r, p))
 107                                 return NULL;
 108                         p->object.flags |= flags;
 109                         prio_queue_put(&queue, p);
 110                 }
 111         }
 112
 113         clear_prio_queue(&queue);
 114         return result;
 115 }
 116
 117 static struct commit_list *merge_bases_many(struct repository *r,
 118                                             struct commit *one, int n,
 119                                             struct commit **twos)
 120 {
 121         struct commit_list *list = NULL;
 122         struct commit_list *result = NULL;
 123         int i;
 124
 125         for (i = 0; i < n; i++) {
 126                 if (one == twos[i])
 127                         /*
 128                          * We do not mark this even with RESULT so we do not
 129                          * have to clean it up.
 130                          */
 131                         return commit_list_insert(one, &result);
 132         }
 133
 134         if (repo_parse_commit(r, one))
 135                 return NULL;
 136         for (i = 0; i < n; i++) {
 137                 if (repo_parse_commit(r, twos[i]))
 138                         return NULL;
 139         }
 140
 141         list = paint_down_to_common(r, one, n, twos, 0);
 142
 143         while (list) {
 144                 struct commit *commit = pop_commit(&list);
 145                 if (!(commit->object.flags & STALE))
 146                         commit_list_insert_by_date(commit, &result);
 147         }
 148         return result;
 149 }
 150
 151 struct commit_list *get_octopus_merge_bases(struct commit_list *in)
 152 {
 153         struct commit_list *i, *j, *k, *ret = NULL;
 154
 155         if (!in)
 156                 return ret;
 157
 158         commit_list_insert(in->item, &ret);
 159
 160         for (i = in->next; i; i = i->next) {
 161                 struct commit_list *new_commits = NULL, *end = NULL;
 162
 163                 for (j = ret; j; j = j->next) {
 164                         struct commit_list *bases;
 165                         bases = get_merge_bases(i->item, j->item);
 166                         if (!new_commits)
 167                                 new_commits = bases;
 168                         else
 169                                 end->next = bases;
 170                         for (k = bases; k; k = k->next)
 171                                 end = k;
 172                 }
 173                 ret = new_commits;
 174         }
 175         return ret;
 176 }
 177
 178 static int remove_redundant_no_gen(struct repository *r,
 179                                    struct commit **array, int cnt)
 180 {
 181         struct commit **work;
 182         unsigned char *redundant;
 183         int *filled_index;
 184         int i, j, filled;
 185
 186         work = xcalloc(cnt, sizeof(*work));
 187         redundant = xcalloc(cnt, 1);
 188         ALLOC_ARRAY(filled_index, cnt - 1);
 189
 190         for (i = 0; i < cnt; i++)
 191                 repo_parse_commit(r, array[i]);
 192         for (i = 0; i < cnt; i++) {
 193                 struct commit_list *common;
 194                 timestamp_t min_generation = commit_graph_generation(array[i]);
 195
 196                 if (redundant[i])
 197                         continue;
 198                 for (j = filled = 0; j < cnt; j++) {
 199                         timestamp_t curr_generation;
 200                         if (i == j || redundant[j])
 201                                 continue;
 202                         filled_index[filled] = j;
 203                         work[filled++] = array[j];
 204
 205                         curr_generation = commit_graph_generation(array[j]);
 206                         if (curr_generation < min_generation)
 207                                 min_generation = curr_generation;
 208                 }
 209                 common = paint_down_to_common(r, array[i], filled,
 210                                               work, min_generation);
 211                 if (array[i]->object.flags & PARENT2)
 212                         redundant[i] = 1;
 213                 for (j = 0; j < filled; j++)
 214                         if (work[j]->object.flags & PARENT1)
 215                                 redundant[filled_index[j]] = 1;
 216                 clear_commit_marks(array[i], all_flags);
 217                 clear_commit_marks_many(filled, work, all_flags);
 218                 free_commit_list(common);
 219         }
 220
 221         /* Now collect the result */
 222         COPY_ARRAY(work, array, cnt);
 223         for (i = filled = 0; i < cnt; i++)
 224                 if (!redundant[i])
 225                         array[filled++] = work[i];
 226         free(work);
 227         free(redundant);
 228         free(filled_index);
 229         return filled;
 230 }
 231
 232 static int remove_redundant_with_gen(struct repository *r,
 233                                      struct commit **array, int cnt)
 234 {
 235         int i, count_non_stale = 0, count_still_independent = cnt;
 236         timestamp_t min_generation = GENERATION_NUMBER_INFINITY;
 237         struct commit **walk_start;
 238         size_t walk_start_nr = 0, walk_start_alloc = cnt;
 239
 240         ALLOC_ARRAY(walk_start, walk_start_alloc);
 241
 242         /* Mark all parents of the input as STALE */
 243         for (i = 0; i < cnt; i++) {
 244                 struct commit_list *parents;
 245                 timestamp_t generation;
 246
 247                 repo_parse_commit(r, array[i]);
 248                 array[i]->object.flags |= RESULT;
 249                 parents = array[i]->parents;
 250
 251                 while (parents) {
 252                         repo_parse_commit(r, parents->item);
 253                         if (!(parents->item->object.flags & STALE)) {
 254                                 parents->item->object.flags |= STALE;
 255                                 ALLOC_GROW(walk_start, walk_start_nr + 1, walk_start_alloc);
 256                                 walk_start[walk_start_nr++] = parents->item;
 257                         }
 258                         parents = parents->next;
 259                 }
 260
 261                 generation = commit_graph_generation(array[i]);
 262
 263                 if (generation < min_generation)
 264                         min_generation = generation;
 265         }
 266
 267         QSORT(walk_start, walk_start_nr, compare_commits_by_gen);
 268
 269         /* remove STALE bit for now to allow walking through parents */
 270         for (i = 0; i < walk_start_nr; i++)
 271                 walk_start[i]->object.flags &= ~STALE;
 272
 273         /*
 274          * Start walking from the highest generation. Hopefully, it will
 275          * find all other items during the first-parent walk, and we can
 276          * terminate early. Otherwise, we will do the same amount of work
 277          * as before.
 278          */
 279         for (i = walk_start_nr - 1; i >= 0 && count_still_independent > 1; i--) {
 280                 /* push the STALE bits up to min generation */
 281                 struct commit_list *stack = NULL;
 282
 283                 commit_list_insert(walk_start[i], &stack);
 284                 walk_start[i]->object.flags |= STALE;
 285
 286                 while (stack) {
 287                         struct commit_list *parents;
 288                         struct commit *c = stack->item;
 289
 290                         repo_parse_commit(r, c);
 291
 292                         if (c->object.flags & RESULT) {
 293                                 c->object.flags &= ~RESULT;
 294                                 if (--count_still_independent <= 1)
 295                                         break;
 296                         }
 297
 298                         if (commit_graph_generation(c) < min_generation) {
 299                                 pop_commit(&stack);
 300                                 continue;
 301                         }
 302
 303                         parents = c->parents;
 304                         while (parents) {
 305                                 if (!(parents->item->object.flags & STALE)) {
 306                                         parents->item->object.flags |= STALE;
 307                                         commit_list_insert(parents->item, &stack);
 308                                         break;
 309                                 }
 310                                 parents = parents->next;
 311                         }
 312
 313                         /* pop if all parents have been visited already */
 314                         if (!parents)
 315                                 pop_commit(&stack);
 316                 }
 317                 free_commit_list(stack);
 318         }
 319
 320         /* clear result */
 321         for (i = 0; i < cnt; i++)
 322                 array[i]->object.flags &= ~RESULT;
 323
 324         /* rearrange array */
 325         for (i = count_non_stale = 0; i < cnt; i++) {
 326                 if (!(array[i]->object.flags & STALE))
 327                         array[count_non_stale++] = array[i];
 328         }
 329
 330         /* clear marks */
 331         clear_commit_marks_many(walk_start_nr, walk_start, STALE);
 332         free(walk_start);
 333
 334         return count_non_stale;
 335 }
 336
 337 static int remove_redundant(struct repository *r, struct commit **array, int cnt)
 338 {
 339         /*
 340          * Some commit in the array may be an ancestor of
 341          * another commit.  Move the independent commits to the
 342          * beginning of 'array' and return their number. Callers
 343          * should not rely upon the contents of 'array' after
 344          * that number.
 345          */
 346         if (generation_numbers_enabled(r)) {
 347                 int i;
 348
 349                 /*
 350                  * If we have a single commit with finite generation
 351                  * number, then the _with_gen algorithm is preferred.
 352                  */
 353                 for (i = 0; i < cnt; i++) {
 354                         if (commit_graph_generation(array[i]) < GENERATION_NUMBER_INFINITY)
 355                                 return remove_redundant_with_gen(r, array, cnt);
 356                 }
 357         }
 358
 359         return remove_redundant_no_gen(r, array, cnt);
 360 }
 361
 362 static struct commit_list *get_merge_bases_many_0(struct repository *r,
 363                                                   struct commit *one,
 364                                                   int n,
 365                                                   struct commit **twos,
 366                                                   int cleanup)
 367 {
 368         struct commit_list *list;
 369         struct commit **rslt;
 370         struct commit_list *result;
 371         int cnt, i;
 372
 373         result = merge_bases_many(r, one, n, twos);
 374         for (i = 0; i < n; i++) {
 375                 if (one == twos[i])
 376                         return result;
 377         }
 378         if (!result || !result->next) {
 379                 if (cleanup) {
 380                         clear_commit_marks(one, all_flags);
 381                         clear_commit_marks_many(n, twos, all_flags);
 382                 }
 383                 return result;
 384         }
 385
 386         /* There are more than one */
 387         cnt = commit_list_count(result);
 388         rslt = xcalloc(cnt, sizeof(*rslt));
 389         for (list = result, i = 0; list; list = list->next)
 390                 rslt[i++] = list->item;
 391         free_commit_list(result);
 392
 393         clear_commit_marks(one, all_flags);
 394         clear_commit_marks_many(n, twos, all_flags);
 395
 396         cnt = remove_redundant(r, rslt, cnt);
 397         result = NULL;
 398         for (i = 0; i < cnt; i++)
 399                 commit_list_insert_by_date(rslt[i], &result);
 400         free(rslt);
 401         return result;
 402 }
 403
 404 struct commit_list *repo_get_merge_bases_many(struct repository *r,
 405                                               struct commit *one,
 406                                               int n,
 407                                               struct commit **twos)
 408 {
 409         return get_merge_bases_many_0(r, one, n, twos, 1);
 410 }
 411
 412 struct commit_list *repo_get_merge_bases_many_dirty(struct repository *r,
 413                                                     struct commit *one,
 414                                                     int n,
 415                                                     struct commit **twos)
 416 {
 417         return get_merge_bases_many_0(r, one, n, twos, 0);
 418 }
 419
 420 struct commit_list *repo_get_merge_bases(struct repository *r,
 421                                          struct commit *one,
 422                                          struct commit *two)
 423 {
 424         return get_merge_bases_many_0(r, one, 1, &two, 1);
 425 }
 426
 427 /*
 428  * Is "commit" a descendant of one of the elements on the "with_commit" list?
 429  */
 430 int repo_is_descendant_of(struct repository *r,
 431                           struct commit *commit,
 432                           struct commit_list *with_commit)
 433 {
 434         if (!with_commit)
 435                 return 1;
 436
 437         if (generation_numbers_enabled(the_repository)) {
 438                 struct commit_list *from_list = NULL;
 439                 int result;
 440                 commit_list_insert(commit, &from_list);
 441                 result = can_all_from_reach(from_list, with_commit, 0);
 442                 free_commit_list(from_list);
 443                 return result;
 444         } else {
 445                 while (with_commit) {
 446                         struct commit *other;
 447
 448                         other = with_commit->item;
 449                         with_commit = with_commit->next;
 450                         if (repo_in_merge_bases_many(r, other, 1, &commit))
 451                                 return 1;
 452                 }
 453                 return 0;
 454         }
 455 }
 456
 457 /*
 458  * Is "commit" an ancestor of one of the "references"?
 459  */
 460 int repo_in_merge_bases_many(struct repository *r, struct commit *commit,
 461                              int nr_reference, struct commit **reference)
 462 {
 463         struct commit_list *bases;
 464         int ret = 0, i;
 465         timestamp_t generation, max_generation = GENERATION_NUMBER_ZERO;
 466
 467         if (repo_parse_commit(r, commit))
 468                 return ret;
 469         for (i = 0; i < nr_reference; i++) {
 470                 if (repo_parse_commit(r, reference[i]))
 471                         return ret;
 472
 473                 generation = commit_graph_generation(reference[i]);
 474                 if (generation > max_generation)
 475                         max_generation = generation;
 476         }
 477
 478         generation = commit_graph_generation(commit);
 479         if (generation > max_generation)
 480                 return ret;
 481
 482         bases = paint_down_to_common(r, commit,
 483                                      nr_reference, reference,
 484                                      generation);
 485         if (commit->object.flags & PARENT2)
 486                 ret = 1;
 487         clear_commit_marks(commit, all_flags);
 488         clear_commit_marks_many(nr_reference, reference, all_flags);
 489         free_commit_list(bases);
 490         return ret;
 491 }
 492
 493 /*
 494  * Is "commit" an ancestor of (i.e. reachable from) the "reference"?
 495  */
 496 int repo_in_merge_bases(struct repository *r,
 497                         struct commit *commit,
 498                         struct commit *reference)
 499 {
 500         int res;
 501         struct commit_list *list = NULL;
 502         struct commit_list **next = &list;
 503
 504         next = commit_list_append(commit, next);
 505         res = repo_is_descendant_of(r, reference, list);
 506         free_commit_list(list);
 507
 508         return res;
 509 }
 510
 511 struct commit_list *reduce_heads(struct commit_list *heads)
 512 {
 513         struct commit_list *p;
 514         struct commit_list *result = NULL, **tail = &result;
 515         struct commit **array;
 516         int num_head, i;
 517
 518         if (!heads)
 519                 return NULL;
 520
 521         /* Uniquify */
 522         for (p = heads; p; p = p->next)
 523                 p->item->object.flags &= ~STALE;
 524         for (p = heads, num_head = 0; p; p = p->next) {
 525                 if (p->item->object.flags & STALE)
 526                         continue;
 527                 p->item->object.flags |= STALE;
 528                 num_head++;
 529         }
 530         array = xcalloc(num_head, sizeof(*array));
 531         for (p = heads, i = 0; p; p = p->next) {
 532                 if (p->item->object.flags & STALE) {
 533                         array[i++] = p->item;
 534                         p->item->object.flags &= ~STALE;
 535                 }
 536         }
 537         num_head = remove_redundant(the_repository, array, num_head);
 538         for (i = 0; i < num_head; i++)
 539                 tail = &commit_list_insert(array[i], tail)->next;
 540         free(array);
 541         return result;
 542 }
 543
 544 void reduce_heads_replace(struct commit_list **heads)
 545 {
 546         struct commit_list *result = reduce_heads(*heads);
 547         free_commit_list(*heads);
 548         *heads = result;
 549 }
 550
 551 int ref_newer(const struct object_id *new_oid, const struct object_id *old_oid)
 552 {
 553         struct object *o;
 554         struct commit *old_commit, *new_commit;
 555         struct commit_list *old_commit_list = NULL;
 556         int ret;
 557
 558         /*
 559          * Both new_commit and old_commit must be commit-ish and new_commit is descendant of
 560          * old_commit.  Otherwise we require --force.
 561          */
 562         o = deref_tag(the_repository, parse_object(the_repository, old_oid),
 563                       NULL, 0);
 564         if (!o || o->type != OBJ_COMMIT)
 565                 return 0;
 566         old_commit = (struct commit *) o;
 567
 568         o = deref_tag(the_repository, parse_object(the_repository, new_oid),
 569                       NULL, 0);
 570         if (!o || o->type != OBJ_COMMIT)
 571                 return 0;
 572         new_commit = (struct commit *) o;
 573
 574         if (parse_commit(new_commit) < 0)
 575                 return 0;
 576
 577         commit_list_insert(old_commit, &old_commit_list);
 578         ret = repo_is_descendant_of(the_repository,
 579                                     new_commit, old_commit_list);
 580         free_commit_list(old_commit_list);
 581         return ret;
 582 }
 583
 584 /*
 585  * Mimicking the real stack, this stack lives on the heap, avoiding stack
 586  * overflows.
 587  *
 588  * At each recursion step, the stack items points to the commits whose
 589  * ancestors are to be inspected.
 590  */
 591 struct contains_stack {
 592         int nr, alloc;
 593         struct contains_stack_entry {
 594                 struct commit *commit;
 595                 struct commit_list *parents;
 596         } *contains_stack;
 597 };
 598
 599 static int in_commit_list(const struct commit_list *want, struct commit *c)
 600 {
 601         for (; want; want = want->next)
 602                 if (oideq(&want->item->object.oid, &c->object.oid))
 603                         return 1;
 604         return 0;
 605 }
 606
 607 /*
 608  * Test whether the candidate is contained in the list.
 609  * Do not recurse to find out, though, but return -1 if inconclusive.
 610  */
 611 static enum contains_result contains_test(struct commit *candidate,
 612                                           const struct commit_list *want,
 613                                           struct contains_cache *cache,
 614                                           timestamp_t cutoff)
 615 {
 616         enum contains_result *cached = contains_cache_at(cache, candidate);
 617
 618         /* If we already have the answer cached, return that. */
 619         if (*cached)
 620                 return *cached;
 621
 622         /* or are we it? */
 623         if (in_commit_list(want, candidate)) {
 624                 *cached = CONTAINS_YES;
 625                 return CONTAINS_YES;
 626         }
 627
 628         /* Otherwise, we don't know; prepare to recurse */
 629         parse_commit_or_die(candidate);
 630
 631         if (commit_graph_generation(candidate) < cutoff)
 632                 return CONTAINS_NO;
 633
 634         return CONTAINS_UNKNOWN;
 635 }
 636
 637 static void push_to_contains_stack(struct commit *candidate, struct contains_stack *contains_stack)
 638 {
 639         ALLOC_GROW(contains_stack->contains_stack, contains_stack->nr + 1, contains_stack->alloc);
 640         contains_stack->contains_stack[contains_stack->nr].commit = candidate;
 641         contains_stack->contains_stack[contains_stack->nr++].parents = candidate->parents;
 642 }
 643
 644 static enum contains_result contains_tag_algo(struct commit *candidate,
 645                                               const struct commit_list *want,
 646                                               struct contains_cache *cache)
 647 {
 648         struct contains_stack contains_stack = { 0, 0, NULL };
 649         enum contains_result result;
 650         timestamp_t cutoff = GENERATION_NUMBER_INFINITY;
 651         const struct commit_list *p;
 652
 653         for (p = want; p; p = p->next) {
 654                 timestamp_t generation;
 655                 struct commit *c = p->item;
 656                 load_commit_graph_info(the_repository, c);
 657                 generation = commit_graph_generation(c);
 658                 if (generation < cutoff)
 659                         cutoff = generation;
 660         }
 661
 662         result = contains_test(candidate, want, cache, cutoff);
 663         if (result != CONTAINS_UNKNOWN)
 664                 return result;
 665
 666         push_to_contains_stack(candidate, &contains_stack);
 667         while (contains_stack.nr) {
 668                 struct contains_stack_entry *entry = &contains_stack.contains_stack[contains_stack.nr - 1];
 669                 struct commit *commit = entry->commit;
 670                 struct commit_list *parents = entry->parents;
 671
 672                 if (!parents) {
 673                         *contains_cache_at(cache, commit) = CONTAINS_NO;
 674                         contains_stack.nr--;
 675                 }
 676                 /*
 677                  * If we just popped the stack, parents->item has been marked,
 678                  * therefore contains_test will return a meaningful yes/no.
 679                  */
 680                 else switch (contains_test(parents->item, want, cache, cutoff)) {
 681                 case CONTAINS_YES:
 682                         *contains_cache_at(cache, commit) = CONTAINS_YES;
 683                         contains_stack.nr--;
 684                         break;
 685                 case CONTAINS_NO:
 686                         entry->parents = parents->next;
 687                         break;
 688                 case CONTAINS_UNKNOWN:
 689                         push_to_contains_stack(parents->item, &contains_stack);
 690                         break;
 691                 }
 692         }
 693         free(contains_stack.contains_stack);
 694         return contains_test(candidate, want, cache, cutoff);
 695 }
 696
 697 int commit_contains(struct ref_filter *filter, struct commit *commit,
 698                     struct commit_list *list, struct contains_cache *cache)
 699 {
 700         if (filter->with_commit_tag_algo)
 701                 return contains_tag_algo(commit, list, cache) == CONTAINS_YES;
 702         return repo_is_descendant_of(the_repository, commit, list);
 703 }
 704
 705 int can_all_from_reach_with_flag(struct object_array *from,
 706                                  unsigned int with_flag,
 707                                  unsigned int assign_flag,
 708                                  time_t min_commit_date,
 709                                  timestamp_t min_generation)
 710 {
 711         struct commit **list = NULL;
 712         int i;
 713         int nr_commits;
 714         int result = 1;
 715
 716         ALLOC_ARRAY(list, from->nr);
 717         nr_commits = 0;
 718         for (i = 0; i < from->nr; i++) {
 719                 struct object *from_one = from->objects[i].item;
 720
 721                 if (!from_one || from_one->flags & assign_flag)
 722                         continue;
 723
 724                 from_one = deref_tag(the_repository, from_one,
 725                                      "a from object", 0);
 726                 if (!from_one || from_one->type != OBJ_COMMIT) {
 727                         /*
 728                          * no way to tell if this is reachable by
 729                          * looking at the ancestry chain alone, so
 730                          * leave a note to ourselves not to worry about
 731                          * this object anymore.
 732                          */
 733                         from->objects[i].item->flags |= assign_flag;
 734                         continue;
 735                 }
 736
 737                 list[nr_commits] = (struct commit *)from_one;
 738                 if (parse_commit(list[nr_commits]) ||
 739                     commit_graph_generation(list[nr_commits]) < min_generation) {
 740                         result = 0;
 741                         goto cleanup;
 742                 }
 743
 744                 nr_commits++;
 745         }
 746
 747         QSORT(list, nr_commits, compare_commits_by_gen);
 748
 749         for (i = 0; i < nr_commits; i++) {
 750                 /* DFS from list[i] */
 751                 struct commit_list *stack = NULL;
 752
 753                 list[i]->object.flags |= assign_flag;
 754                 commit_list_insert(list[i], &stack);
 755
 756                 while (stack) {
 757                         struct commit_list *parent;
 758
 759                         if (stack->item->object.flags & (with_flag | RESULT)) {
 760                                 pop_commit(&stack);
 761                                 if (stack)
 762                                         stack->item->object.flags |= RESULT;
 763                                 continue;
 764                         }
 765
 766                         for (parent = stack->item->parents; parent; parent = parent->next) {
 767                                 if (parent->item->object.flags & (with_flag | RESULT))
 768                                         stack->item->object.flags |= RESULT;
 769
 770                                 if (!(parent->item->object.flags & assign_flag)) {
 771                                         parent->item->object.flags |= assign_flag;
 772
 773                                         if (parse_commit(parent->item) ||
 774                                             parent->item->date < min_commit_date ||
 775                                             commit_graph_generation(parent->item) < min_generation)
 776                                                 continue;
 777
 778                                         commit_list_insert(parent->item, &stack);
 779                                         break;
 780                                 }
 781                         }
 782
 783                         if (!parent)
 784                                 pop_commit(&stack);
 785                 }
 786
 787                 if (!(list[i]->object.flags & (with_flag | RESULT))) {
 788                         result = 0;
 789                         goto cleanup;
 790                 }
 791         }
 792
 793 cleanup:
 794         clear_commit_marks_many(nr_commits, list, RESULT | assign_flag);
 795         free(list);
 796
 797         for (i = 0; i < from->nr; i++)
 798                 from->objects[i].item->flags &= ~assign_flag;
 799
 800         return result;
 801 }
 802
 803 int can_all_from_reach(struct commit_list *from, struct commit_list *to,
 804                        int cutoff_by_min_date)
 805 {
 806         struct object_array from_objs = OBJECT_ARRAY_INIT;
 807         time_t min_commit_date = cutoff_by_min_date ? from->item->date : 0;
 808         struct commit_list *from_iter = from, *to_iter = to;
 809         int result;
 810         timestamp_t min_generation = GENERATION_NUMBER_INFINITY;
 811
 812         while (from_iter) {
 813                 add_object_array(&from_iter->item->object, NULL, &from_objs);
 814
 815                 if (!parse_commit(from_iter->item)) {
 816                         timestamp_t generation;
 817                         if (from_iter->item->date < min_commit_date)
 818                                 min_commit_date = from_iter->item->date;
 819
 820                         generation = commit_graph_generation(from_iter->item);
 821                         if (generation < min_generation)
 822                                 min_generation = generation;
 823                 }
 824
 825                 from_iter = from_iter->next;
 826         }
 827
 828         while (to_iter) {
 829                 if (!parse_commit(to_iter->item)) {
 830                         timestamp_t generation;
 831                         if (to_iter->item->date < min_commit_date)
 832                                 min_commit_date = to_iter->item->date;
 833
 834                         generation = commit_graph_generation(to_iter->item);
 835                         if (generation < min_generation)
 836                                 min_generation = generation;
 837                 }
 838
 839                 to_iter->item->object.flags |= PARENT2;
 840
 841                 to_iter = to_iter->next;
 842         }
 843
 844         result = can_all_from_reach_with_flag(&from_objs, PARENT2, PARENT1,
 845                                               min_commit_date, min_generation);
 846
 847         while (from) {
 848                 clear_commit_marks(from->item, PARENT1);
 849                 from = from->next;
 850         }
 851
 852         while (to) {
 853                 clear_commit_marks(to->item, PARENT2);
 854                 to = to->next;
 855         }
 856
 857         object_array_clear(&from_objs);
 858         return result;
 859 }
 860
 861 struct commit_list *get_reachable_subset(struct commit **from, int nr_from,
 862                                          struct commit **to, int nr_to,
 863                                          unsigned int reachable_flag)
 864 {
 865         struct commit **item;
 866         struct commit *current;
 867         struct commit_list *found_commits = NULL;
 868         struct commit **to_last = to + nr_to;
 869         struct commit **from_last = from + nr_from;
 870         timestamp_t min_generation = GENERATION_NUMBER_INFINITY;
 871         int num_to_find = 0;
 872
 873         struct prio_queue queue = { compare_commits_by_gen_then_commit_date };
 874
 875         for (item = to; item < to_last; item++) {
 876                 timestamp_t generation;
 877                 struct commit *c = *item;
 878
 879                 parse_commit(c);
 880                 generation = commit_graph_generation(c);
 881                 if (generation < min_generation)
 882                         min_generation = generation;
 883
 884                 if (!(c->object.flags & PARENT1)) {
 885                         c->object.flags |= PARENT1;
 886                         num_to_find++;
 887                 }
 888         }
 889
 890         for (item = from; item < from_last; item++) {
 891                 struct commit *c = *item;
 892                 if (!(c->object.flags & PARENT2)) {
 893                         c->object.flags |= PARENT2;
 894                         parse_commit(c);
 895
 896                         prio_queue_put(&queue, *item);
 897                 }
 898         }
 899
 900         while (num_to_find && (current = prio_queue_get(&queue)) != NULL) {
 901                 struct commit_list *parents;
 902
 903                 if (current->object.flags & PARENT1) {
 904                         current->object.flags &= ~PARENT1;
 905                         current->object.flags |= reachable_flag;
 906                         commit_list_insert(current, &found_commits);
 907                         num_to_find--;
 908                 }
 909
 910                 for (parents = current->parents; parents; parents = parents->next) {
 911                         struct commit *p = parents->item;
 912
 913                         parse_commit(p);
 914
 915                         if (commit_graph_generation(p) < min_generation)
 916                                 continue;
 917
 918                         if (p->object.flags & PARENT2)
 919                                 continue;
 920
 921                         p->object.flags |= PARENT2;
 922                         prio_queue_put(&queue, p);
 923                 }
 924         }
 925
 926         clear_commit_marks_many(nr_to, to, PARENT1);
 927         clear_commit_marks_many(nr_from, from, PARENT2);
 928
 929         return found_commits;
 930 }