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 int paint_down_to_common(struct repository *r,
  53                                 struct commit *one, int n,
  54                                 struct commit **twos,
  55                                 timestamp_t min_generation,
  56                                 int ignore_missing_commits,
  57                                 struct commit_list **result)
  58 {
  59         struct prio_queue queue = { compare_commits_by_gen_then_commit_date };
  60         int i;
  61         timestamp_t last_gen = GENERATION_NUMBER_INFINITY;
  62
  63         if (!min_generation && !corrected_commit_dates_enabled(r))
  64                 queue.compare = compare_commits_by_commit_date;
  65
  66         one->object.flags |= PARENT1;
  67         if (!n) {
  68                 commit_list_append(one, result);
  69                 return 0;
  70         }
  71         prio_queue_put(&queue, one);
  72
  73         for (i = 0; i < n; i++) {
  74                 twos[i]->object.flags |= PARENT2;
  75                 prio_queue_put(&queue, twos[i]);
  76         }
  77
  78         while (queue_has_nonstale(&queue)) {
  79                 struct commit *commit = prio_queue_get(&queue);
  80                 struct commit_list *parents;
  81                 int flags;
  82                 timestamp_t generation = commit_graph_generation(commit);
  83
  84                 if (min_generation && generation > last_gen)
  85                         BUG("bad generation skip %"PRItime" > %"PRItime" at %s",
  86                             generation, last_gen,
  87                             oid_to_hex(&commit->object.oid));
  88                 last_gen = generation;
  89
  90                 if (generation < min_generation)
  91                         break;
  92
  93                 flags = commit->object.flags & (PARENT1 | PARENT2 | STALE);
  94                 if (flags == (PARENT1 | PARENT2)) {
  95                         if (!(commit->object.flags & RESULT)) {
  96                                 commit->object.flags |= RESULT;
  97                                 commit_list_insert_by_date(commit, result);
  98                         }
  99                         /* Mark parents of a found merge stale */
 100                         flags |= STALE;
 101                 }
 102                 parents = commit->parents;
 103                 while (parents) {
 104                         struct commit *p = parents->item;
 105                         parents = parents->next;
 106                         if ((p->object.flags & flags) == flags)
 107                                 continue;
 108                         if (repo_parse_commit(r, p)) {
 109                                 clear_prio_queue(&queue);
 110                                 free_commit_list(*result);
 111                                 *result = NULL;
 112                                 /*
 113                                  * At this stage, we know that the commit is
 114                                  * missing: `repo_parse_commit()` uses
 115                                  * `OBJECT_INFO_DIE_IF_CORRUPT` and therefore
 116                                  * corrupt commits would already have been
 117                                  * dispatched with a `die()`.
 118                                  */
 119                                 if (ignore_missing_commits)
 120                                         return 0;
 121                                 return error(_("could not parse commit %s"),
 122                                              oid_to_hex(&p->object.oid));
 123                         }
 124                         p->object.flags |= flags;
 125                         prio_queue_put(&queue, p);
 126                 }
 127         }
 128
 129         clear_prio_queue(&queue);
 130         return 0;
 131 }
 132
 133 static int merge_bases_many(struct repository *r,
 134                             struct commit *one, int n,
 135                             struct commit **twos,
 136                             struct commit_list **result)
 137 {
 138         struct commit_list *list = NULL;
 139         int i;
 140
 141         for (i = 0; i < n; i++) {
 142                 if (one == twos[i]) {
 143                         /*
 144                          * We do not mark this even with RESULT so we do not
 145                          * have to clean it up.
 146                          */
 147                         *result = commit_list_insert(one, result);
 148                         return 0;
 149                 }
 150         }
 151
 152         if (!one)
 153                 return 0;
 154         if (repo_parse_commit(r, one))
 155                 return error(_("could not parse commit %s"),
 156                              oid_to_hex(&one->object.oid));
 157         for (i = 0; i < n; i++) {
 158                 if (!twos[i])
 159                         return 0;
 160                 if (repo_parse_commit(r, twos[i]))
 161                         return error(_("could not parse commit %s"),
 162                                      oid_to_hex(&twos[i]->object.oid));
 163         }
 164
 165         if (paint_down_to_common(r, one, n, twos, 0, 0, &list)) {
 166                 free_commit_list(list);
 167                 return -1;
 168         }
 169
 170         while (list) {
 171                 struct commit *commit = pop_commit(&list);
 172                 if (!(commit->object.flags & STALE))
 173                         commit_list_insert_by_date(commit, result);
 174         }
 175         return 0;
 176 }
 177
 178 int get_octopus_merge_bases(struct commit_list *in, struct commit_list **result)
 179 {
 180         struct commit_list *i, *j, *k;
 181
 182         if (!in)
 183                 return 0;
 184
 185         commit_list_insert(in->item, result);
 186
 187         for (i = in->next; i; i = i->next) {
 188                 struct commit_list *new_commits = NULL, *end = NULL;
 189
 190                 for (j = *result; j; j = j->next) {
 191                         struct commit_list *bases = NULL;
 192                         if (repo_get_merge_bases(the_repository, i->item,
 193                                                  j->item, &bases) < 0) {
 194                                 free_commit_list(bases);
 195                                 free_commit_list(*result);
 196                                 *result = NULL;
 197                                 return -1;
 198                         }
 199                         if (!new_commits)
 200                                 new_commits = bases;
 201                         else
 202                                 end->next = bases;
 203                         for (k = bases; k; k = k->next)
 204                                 end = k;
 205                 }
 206                 free_commit_list(*result);
 207                 *result = new_commits;
 208         }
 209         return 0;
 210 }
 211
 212 static int remove_redundant_no_gen(struct repository *r,
 213                                    struct commit **array, int cnt)
 214 {
 215         struct commit **work;
 216         unsigned char *redundant;
 217         int *filled_index;
 218         int i, j, filled;
 219
 220         CALLOC_ARRAY(work, cnt);
 221         redundant = xcalloc(cnt, 1);
 222         ALLOC_ARRAY(filled_index, cnt - 1);
 223
 224         for (i = 0; i < cnt; i++)
 225                 repo_parse_commit(r, array[i]);
 226         for (i = 0; i < cnt; i++) {
 227                 struct commit_list *common = NULL;
 228                 timestamp_t min_generation = commit_graph_generation(array[i]);
 229
 230                 if (redundant[i])
 231                         continue;
 232                 for (j = filled = 0; j < cnt; j++) {
 233                         timestamp_t curr_generation;
 234                         if (i == j || redundant[j])
 235                                 continue;
 236                         filled_index[filled] = j;
 237                         work[filled++] = array[j];
 238
 239                         curr_generation = commit_graph_generation(array[j]);
 240                         if (curr_generation < min_generation)
 241                                 min_generation = curr_generation;
 242                 }
 243                 if (paint_down_to_common(r, array[i], filled,
 244                                          work, min_generation, 0, &common)) {
 245                         clear_commit_marks(array[i], all_flags);
 246                         clear_commit_marks_many(filled, work, all_flags);
 247                         free_commit_list(common);
 248                         free(work);
 249                         free(redundant);
 250                         free(filled_index);
 251                         return -1;
 252                 }
 253                 if (array[i]->object.flags & PARENT2)
 254                         redundant[i] = 1;
 255                 for (j = 0; j < filled; j++)
 256                         if (work[j]->object.flags & PARENT1)
 257                                 redundant[filled_index[j]] = 1;
 258                 clear_commit_marks(array[i], all_flags);
 259                 clear_commit_marks_many(filled, work, all_flags);
 260                 free_commit_list(common);
 261         }
 262
 263         /* Now collect the result */
 264         COPY_ARRAY(work, array, cnt);
 265         for (i = filled = 0; i < cnt; i++)
 266                 if (!redundant[i])
 267                         array[filled++] = work[i];
 268         free(work);
 269         free(redundant);
 270         free(filled_index);
 271         return filled;
 272 }
 273
 274 static int remove_redundant_with_gen(struct repository *r,
 275                                      struct commit **array, int cnt)
 276 {
 277         int i, count_non_stale = 0, count_still_independent = cnt;
 278         timestamp_t min_generation = GENERATION_NUMBER_INFINITY;
 279         struct commit **walk_start, **sorted;
 280         size_t walk_start_nr = 0, walk_start_alloc = cnt;
 281         int min_gen_pos = 0;
 282
 283         /*
 284          * Sort the input by generation number, ascending. This allows
 285          * us to increase the "min_generation" limit when we discover
 286          * the commit with lowest generation is STALE. The index
 287          * min_gen_pos points to the current position within 'array'
 288          * that is not yet known to be STALE.
 289          */
 290         DUP_ARRAY(sorted, array, cnt);
 291         QSORT(sorted, cnt, compare_commits_by_gen);
 292         min_generation = commit_graph_generation(sorted[0]);
 293
 294         ALLOC_ARRAY(walk_start, walk_start_alloc);
 295
 296         /* Mark all parents of the input as STALE */
 297         for (i = 0; i < cnt; i++) {
 298                 struct commit_list *parents;
 299
 300                 repo_parse_commit(r, array[i]);
 301                 array[i]->object.flags |= RESULT;
 302                 parents = array[i]->parents;
 303
 304                 while (parents) {
 305                         repo_parse_commit(r, parents->item);
 306                         if (!(parents->item->object.flags & STALE)) {
 307                                 parents->item->object.flags |= STALE;
 308                                 ALLOC_GROW(walk_start, walk_start_nr + 1, walk_start_alloc);
 309                                 walk_start[walk_start_nr++] = parents->item;
 310                         }
 311                         parents = parents->next;
 312                 }
 313         }
 314
 315         QSORT(walk_start, walk_start_nr, compare_commits_by_gen);
 316
 317         /* remove STALE bit for now to allow walking through parents */
 318         for (i = 0; i < walk_start_nr; i++)
 319                 walk_start[i]->object.flags &= ~STALE;
 320
 321         /*
 322          * Start walking from the highest generation. Hopefully, it will
 323          * find all other items during the first-parent walk, and we can
 324          * terminate early. Otherwise, we will do the same amount of work
 325          * as before.
 326          */
 327         for (i = walk_start_nr - 1; i >= 0 && count_still_independent > 1; i--) {
 328                 /* push the STALE bits up to min generation */
 329                 struct commit_list *stack = NULL;
 330
 331                 commit_list_insert(walk_start[i], &stack);
 332                 walk_start[i]->object.flags |= STALE;
 333
 334                 while (stack) {
 335                         struct commit_list *parents;
 336                         struct commit *c = stack->item;
 337
 338                         repo_parse_commit(r, c);
 339
 340                         if (c->object.flags & RESULT) {
 341                                 c->object.flags &= ~RESULT;
 342                                 if (--count_still_independent <= 1)
 343                                         break;
 344                                 if (oideq(&c->object.oid, &sorted[min_gen_pos]->object.oid)) {
 345                                         while (min_gen_pos < cnt - 1 &&
 346                                                (sorted[min_gen_pos]->object.flags & STALE))
 347                                                 min_gen_pos++;
 348                                         min_generation = commit_graph_generation(sorted[min_gen_pos]);
 349                                 }
 350                         }
 351
 352                         if (commit_graph_generation(c) < min_generation) {
 353                                 pop_commit(&stack);
 354                                 continue;
 355                         }
 356
 357                         parents = c->parents;
 358                         while (parents) {
 359                                 if (!(parents->item->object.flags & STALE)) {
 360                                         parents->item->object.flags |= STALE;
 361                                         commit_list_insert(parents->item, &stack);
 362                                         break;
 363                                 }
 364                                 parents = parents->next;
 365                         }
 366
 367                         /* pop if all parents have been visited already */
 368                         if (!parents)
 369                                 pop_commit(&stack);
 370                 }
 371                 free_commit_list(stack);
 372         }
 373         free(sorted);
 374
 375         /* clear result */
 376         for (i = 0; i < cnt; i++)
 377                 array[i]->object.flags &= ~RESULT;
 378
 379         /* rearrange array */
 380         for (i = count_non_stale = 0; i < cnt; i++) {
 381                 if (!(array[i]->object.flags & STALE))
 382                         array[count_non_stale++] = array[i];
 383         }
 384
 385         /* clear marks */
 386         clear_commit_marks_many(walk_start_nr, walk_start, STALE);
 387         free(walk_start);
 388
 389         return count_non_stale;
 390 }
 391
 392 static int remove_redundant(struct repository *r, struct commit **array, int cnt)
 393 {
 394         /*
 395          * Some commit in the array may be an ancestor of
 396          * another commit.  Move the independent commits to the
 397          * beginning of 'array' and return their number. Callers
 398          * should not rely upon the contents of 'array' after
 399          * that number.
 400          */
 401         if (generation_numbers_enabled(r)) {
 402                 int i;
 403
 404                 /*
 405                  * If we have a single commit with finite generation
 406                  * number, then the _with_gen algorithm is preferred.
 407                  */
 408                 for (i = 0; i < cnt; i++) {
 409                         if (commit_graph_generation(array[i]) < GENERATION_NUMBER_INFINITY)
 410                                 return remove_redundant_with_gen(r, array, cnt);
 411                 }
 412         }
 413
 414         return remove_redundant_no_gen(r, array, cnt);
 415 }
 416
 417 static int get_merge_bases_many_0(struct repository *r,
 418                                   struct commit *one,
 419                                   int n,
 420                                   struct commit **twos,
 421                                   int cleanup,
 422                                   struct commit_list **result)
 423 {
 424         struct commit_list *list;
 425         struct commit **rslt;
 426         int cnt, i;
 427
 428         if (merge_bases_many(r, one, n, twos, result) < 0)
 429                 return -1;
 430         for (i = 0; i < n; i++) {
 431                 if (one == twos[i])
 432                         return 0;
 433         }
 434         if (!*result || !(*result)->next) {
 435                 if (cleanup) {
 436                         clear_commit_marks(one, all_flags);
 437                         clear_commit_marks_many(n, twos, all_flags);
 438                 }
 439                 return 0;
 440         }
 441
 442         /* There are more than one */
 443         cnt = commit_list_count(*result);
 444         CALLOC_ARRAY(rslt, cnt);
 445         for (list = *result, i = 0; list; list = list->next)
 446                 rslt[i++] = list->item;
 447         free_commit_list(*result);
 448         *result = NULL;
 449
 450         clear_commit_marks(one, all_flags);
 451         clear_commit_marks_many(n, twos, all_flags);
 452
 453         cnt = remove_redundant(r, rslt, cnt);
 454         if (cnt < 0) {
 455                 free(rslt);
 456                 return -1;
 457         }
 458         for (i = 0; i < cnt; i++)
 459                 commit_list_insert_by_date(rslt[i], result);
 460         free(rslt);
 461         return 0;
 462 }
 463
 464 int repo_get_merge_bases_many(struct repository *r,
 465                               struct commit *one,
 466                               int n,
 467                               struct commit **twos,
 468                               struct commit_list **result)
 469 {
 470         return get_merge_bases_many_0(r, one, n, twos, 1, result);
 471 }
 472
 473 int repo_get_merge_bases_many_dirty(struct repository *r,
 474                                     struct commit *one,
 475                                     int n,
 476                                     struct commit **twos,
 477                                     struct commit_list **result)
 478 {
 479         return get_merge_bases_many_0(r, one, n, twos, 0, result);
 480 }
 481
 482 int repo_get_merge_bases(struct repository *r,
 483                          struct commit *one,
 484                          struct commit *two,
 485                          struct commit_list **result)
 486 {
 487         return get_merge_bases_many_0(r, one, 1, &two, 1, result);
 488 }
 489
 490 /*
 491  * Is "commit" a descendant of one of the elements on the "with_commit" list?
 492  */
 493 int repo_is_descendant_of(struct repository *r,
 494                           struct commit *commit,
 495                           struct commit_list *with_commit)
 496 {
 497         if (!with_commit)
 498                 return 1;
 499
 500         if (generation_numbers_enabled(r)) {
 501                 struct commit_list *from_list = NULL;
 502                 int result;
 503                 commit_list_insert(commit, &from_list);
 504                 result = can_all_from_reach(from_list, with_commit, 0);
 505                 free_commit_list(from_list);
 506                 return result;
 507         } else {
 508                 while (with_commit) {
 509                         struct commit *other;
 510                         int ret;
 511
 512                         other = with_commit->item;
 513                         with_commit = with_commit->next;
 514                         ret = repo_in_merge_bases_many(r, other, 1, &commit, 0);
 515                         if (ret)
 516                                 return ret;
 517                 }
 518                 return 0;
 519         }
 520 }
 521
 522 /*
 523  * Is "commit" an ancestor of one of the "references"?
 524  */
 525 int repo_in_merge_bases_many(struct repository *r, struct commit *commit,
 526                              int nr_reference, struct commit **reference,
 527                              int ignore_missing_commits)
 528 {
 529         struct commit_list *bases = NULL;
 530         int ret = 0, i;
 531         timestamp_t generation, max_generation = GENERATION_NUMBER_ZERO;
 532
 533         if (repo_parse_commit(r, commit))
 534                 return ignore_missing_commits ? 0 : -1;
 535         for (i = 0; i < nr_reference; i++) {
 536                 if (repo_parse_commit(r, reference[i]))
 537                         return ignore_missing_commits ? 0 : -1;
 538
 539                 generation = commit_graph_generation(reference[i]);
 540                 if (generation > max_generation)
 541                         max_generation = generation;
 542         }
 543
 544         generation = commit_graph_generation(commit);
 545         if (generation > max_generation)
 546                 return ret;
 547
 548         if (paint_down_to_common(r, commit,
 549                                  nr_reference, reference,
 550                                  generation, ignore_missing_commits, &bases))
 551                 ret = -1;
 552         else if (commit->object.flags & PARENT2)
 553                 ret = 1;
 554         clear_commit_marks(commit, all_flags);
 555         clear_commit_marks_many(nr_reference, reference, all_flags);
 556         free_commit_list(bases);
 557         return ret;
 558 }
 559
 560 /*
 561  * Is "commit" an ancestor of (i.e. reachable from) the "reference"?
 562  */
 563 int repo_in_merge_bases(struct repository *r,
 564                         struct commit *commit,
 565                         struct commit *reference)
 566 {
 567         int res;
 568         struct commit_list *list = NULL;
 569         struct commit_list **next = &list;
 570
 571         next = commit_list_append(commit, next);
 572         res = repo_is_descendant_of(r, reference, list);
 573         free_commit_list(list);
 574
 575         return res;
 576 }
 577
 578 struct commit_list *reduce_heads(struct commit_list *heads)
 579 {
 580         struct commit_list *p;
 581         struct commit_list *result = NULL, **tail = &result;
 582         struct commit **array;
 583         int num_head, i;
 584
 585         if (!heads)
 586                 return NULL;
 587
 588         /* Uniquify */
 589         for (p = heads; p; p = p->next)
 590                 p->item->object.flags &= ~STALE;
 591         for (p = heads, num_head = 0; p; p = p->next) {
 592                 if (p->item->object.flags & STALE)
 593                         continue;
 594                 p->item->object.flags |= STALE;
 595                 num_head++;
 596         }
 597         CALLOC_ARRAY(array, num_head);
 598         for (p = heads, i = 0; p; p = p->next) {
 599                 if (p->item->object.flags & STALE) {
 600                         array[i++] = p->item;
 601                         p->item->object.flags &= ~STALE;
 602                 }
 603         }
 604         num_head = remove_redundant(the_repository, array, num_head);
 605         if (num_head < 0) {
 606                 free(array);
 607                 return NULL;
 608         }
 609         for (i = 0; i < num_head; i++)
 610                 tail = &commit_list_insert(array[i], tail)->next;
 611         free(array);
 612         return result;
 613 }
 614
 615 void reduce_heads_replace(struct commit_list **heads)
 616 {
 617         struct commit_list *result = reduce_heads(*heads);
 618         free_commit_list(*heads);
 619         *heads = result;
 620 }
 621
 622 int ref_newer(const struct object_id *new_oid, const struct object_id *old_oid)
 623 {
 624         struct object *o;
 625         struct commit *old_commit, *new_commit;
 626         struct commit_list *old_commit_list = NULL;
 627         int ret;
 628
 629         /*
 630          * Both new_commit and old_commit must be commit-ish and new_commit is descendant of
 631          * old_commit.  Otherwise we require --force.
 632          */
 633         o = deref_tag(the_repository, parse_object(the_repository, old_oid),
 634                       NULL, 0);
 635         if (!o || o->type != OBJ_COMMIT)
 636                 return 0;
 637         old_commit = (struct commit *) o;
 638
 639         o = deref_tag(the_repository, parse_object(the_repository, new_oid),
 640                       NULL, 0);
 641         if (!o || o->type != OBJ_COMMIT)
 642                 return 0;
 643         new_commit = (struct commit *) o;
 644
 645         if (repo_parse_commit(the_repository, new_commit) < 0)
 646                 return 0;
 647
 648         commit_list_insert(old_commit, &old_commit_list);
 649         ret = repo_is_descendant_of(the_repository,
 650                                     new_commit, old_commit_list);
 651         if (ret < 0)
 652                 exit(128);
 653         free_commit_list(old_commit_list);
 654         return ret;
 655 }
 656
 657 /*
 658  * Mimicking the real stack, this stack lives on the heap, avoiding stack
 659  * overflows.
 660  *
 661  * At each recursion step, the stack items points to the commits whose
 662  * ancestors are to be inspected.
 663  */
 664 struct contains_stack {
 665         int nr, alloc;
 666         struct contains_stack_entry {
 667                 struct commit *commit;
 668                 struct commit_list *parents;
 669         } *contains_stack;
 670 };
 671
 672 static int in_commit_list(const struct commit_list *want, struct commit *c)
 673 {
 674         for (; want; want = want->next)
 675                 if (oideq(&want->item->object.oid, &c->object.oid))
 676                         return 1;
 677         return 0;
 678 }
 679
 680 /*
 681  * Test whether the candidate is contained in the list.
 682  * Do not recurse to find out, though, but return -1 if inconclusive.
 683  */
 684 static enum contains_result contains_test(struct commit *candidate,
 685                                           const struct commit_list *want,
 686                                           struct contains_cache *cache,
 687                                           timestamp_t cutoff)
 688 {
 689         enum contains_result *cached = contains_cache_at(cache, candidate);
 690
 691         /* If we already have the answer cached, return that. */
 692         if (*cached)
 693                 return *cached;
 694
 695         /* or are we it? */
 696         if (in_commit_list(want, candidate)) {
 697                 *cached = CONTAINS_YES;
 698                 return CONTAINS_YES;
 699         }
 700
 701         /* Otherwise, we don't know; prepare to recurse */
 702         parse_commit_or_die(candidate);
 703
 704         if (commit_graph_generation(candidate) < cutoff)
 705                 return CONTAINS_NO;
 706
 707         return CONTAINS_UNKNOWN;
 708 }
 709
 710 static void push_to_contains_stack(struct commit *candidate, struct contains_stack *contains_stack)
 711 {
 712         ALLOC_GROW(contains_stack->contains_stack, contains_stack->nr + 1, contains_stack->alloc);
 713         contains_stack->contains_stack[contains_stack->nr].commit = candidate;
 714         contains_stack->contains_stack[contains_stack->nr++].parents = candidate->parents;
 715 }
 716
 717 static enum contains_result contains_tag_algo(struct commit *candidate,
 718                                               const struct commit_list *want,
 719                                               struct contains_cache *cache)
 720 {
 721         struct contains_stack contains_stack = { 0, 0, NULL };
 722         enum contains_result result;
 723         timestamp_t cutoff = GENERATION_NUMBER_INFINITY;
 724         const struct commit_list *p;
 725
 726         for (p = want; p; p = p->next) {
 727                 timestamp_t generation;
 728                 struct commit *c = p->item;
 729                 load_commit_graph_info(the_repository, c);
 730                 generation = commit_graph_generation(c);
 731                 if (generation < cutoff)
 732                         cutoff = generation;
 733         }
 734
 735         result = contains_test(candidate, want, cache, cutoff);
 736         if (result != CONTAINS_UNKNOWN)
 737                 return result;
 738
 739         push_to_contains_stack(candidate, &contains_stack);
 740         while (contains_stack.nr) {
 741                 struct contains_stack_entry *entry = &contains_stack.contains_stack[contains_stack.nr - 1];
 742                 struct commit *commit = entry->commit;
 743                 struct commit_list *parents = entry->parents;
 744
 745                 if (!parents) {
 746                         *contains_cache_at(cache, commit) = CONTAINS_NO;
 747                         contains_stack.nr--;
 748                 }
 749                 /*
 750                  * If we just popped the stack, parents->item has been marked,
 751                  * therefore contains_test will return a meaningful yes/no.
 752                  */
 753                 else switch (contains_test(parents->item, want, cache, cutoff)) {
 754                 case CONTAINS_YES:
 755                         *contains_cache_at(cache, commit) = CONTAINS_YES;
 756                         contains_stack.nr--;
 757                         break;
 758                 case CONTAINS_NO:
 759                         entry->parents = parents->next;
 760                         break;
 761                 case CONTAINS_UNKNOWN:
 762                         push_to_contains_stack(parents->item, &contains_stack);
 763                         break;
 764                 }
 765         }
 766         free(contains_stack.contains_stack);
 767         return contains_test(candidate, want, cache, cutoff);
 768 }
 769
 770 int commit_contains(struct ref_filter *filter, struct commit *commit,
 771                     struct commit_list *list, struct contains_cache *cache)
 772 {
 773         if (filter->with_commit_tag_algo)
 774                 return contains_tag_algo(commit, list, cache) == CONTAINS_YES;
 775         return repo_is_descendant_of(the_repository, commit, list);
 776 }
 777
 778 int can_all_from_reach_with_flag(struct object_array *from,
 779                                  unsigned int with_flag,
 780                                  unsigned int assign_flag,
 781                                  time_t min_commit_date,
 782                                  timestamp_t min_generation)
 783 {
 784         struct commit **list = NULL;
 785         int i;
 786         int nr_commits;
 787         int result = 1;
 788
 789         ALLOC_ARRAY(list, from->nr);
 790         nr_commits = 0;
 791         for (i = 0; i < from->nr; i++) {
 792                 struct object *from_one = from->objects[i].item;
 793
 794                 if (!from_one || from_one->flags & assign_flag)
 795                         continue;
 796
 797                 from_one = deref_tag(the_repository, from_one,
 798                                      "a from object", 0);
 799                 if (!from_one || from_one->type != OBJ_COMMIT) {
 800                         /*
 801                          * no way to tell if this is reachable by
 802                          * looking at the ancestry chain alone, so
 803                          * leave a note to ourselves not to worry about
 804                          * this object anymore.
 805                          */
 806                         from->objects[i].item->flags |= assign_flag;
 807                         continue;
 808                 }
 809
 810                 list[nr_commits] = (struct commit *)from_one;
 811                 if (repo_parse_commit(the_repository, list[nr_commits]) ||
 812                     commit_graph_generation(list[nr_commits]) < min_generation) {
 813                         result = 0;
 814                         goto cleanup;
 815                 }
 816
 817                 nr_commits++;
 818         }
 819
 820         QSORT(list, nr_commits, compare_commits_by_gen);
 821
 822         for (i = 0; i < nr_commits; i++) {
 823                 /* DFS from list[i] */
 824                 struct commit_list *stack = NULL;
 825
 826                 list[i]->object.flags |= assign_flag;
 827                 commit_list_insert(list[i], &stack);
 828
 829                 while (stack) {
 830                         struct commit_list *parent;
 831
 832                         if (stack->item->object.flags & (with_flag | RESULT)) {
 833                                 pop_commit(&stack);
 834                                 if (stack)
 835                                         stack->item->object.flags |= RESULT;
 836                                 continue;
 837                         }
 838
 839                         for (parent = stack->item->parents; parent; parent = parent->next) {
 840                                 if (parent->item->object.flags & (with_flag | RESULT))
 841                                         stack->item->object.flags |= RESULT;
 842
 843                                 if (!(parent->item->object.flags & assign_flag)) {
 844                                         parent->item->object.flags |= assign_flag;
 845
 846                                         if (repo_parse_commit(the_repository, parent->item) ||
 847                                             parent->item->date < min_commit_date ||
 848                                             commit_graph_generation(parent->item) < min_generation)
 849                                                 continue;
 850
 851                                         commit_list_insert(parent->item, &stack);
 852                                         break;
 853                                 }
 854                         }
 855
 856                         if (!parent)
 857                                 pop_commit(&stack);
 858                 }
 859
 860                 if (!(list[i]->object.flags & (with_flag | RESULT))) {
 861                         result = 0;
 862                         goto cleanup;
 863                 }
 864         }
 865
 866 cleanup:
 867         clear_commit_marks_many(nr_commits, list, RESULT | assign_flag);
 868         free(list);
 869
 870         for (i = 0; i < from->nr; i++) {
 871                 struct object *from_one = from->objects[i].item;
 872
 873                 if (from_one)
 874                         from_one->flags &= ~assign_flag;
 875         }
 876
 877         return result;
 878 }
 879
 880 int can_all_from_reach(struct commit_list *from, struct commit_list *to,
 881                        int cutoff_by_min_date)
 882 {
 883         struct object_array from_objs = OBJECT_ARRAY_INIT;
 884         time_t min_commit_date = cutoff_by_min_date ? from->item->date : 0;
 885         struct commit_list *from_iter = from, *to_iter = to;
 886         int result;
 887         timestamp_t min_generation = GENERATION_NUMBER_INFINITY;
 888
 889         while (from_iter) {
 890                 add_object_array(&from_iter->item->object, NULL, &from_objs);
 891
 892                 if (!repo_parse_commit(the_repository, from_iter->item)) {
 893                         timestamp_t generation;
 894                         if (from_iter->item->date < min_commit_date)
 895                                 min_commit_date = from_iter->item->date;
 896
 897                         generation = commit_graph_generation(from_iter->item);
 898                         if (generation < min_generation)
 899                                 min_generation = generation;
 900                 }
 901
 902                 from_iter = from_iter->next;
 903         }
 904
 905         while (to_iter) {
 906                 if (!repo_parse_commit(the_repository, to_iter->item)) {
 907                         timestamp_t generation;
 908                         if (to_iter->item->date < min_commit_date)
 909                                 min_commit_date = to_iter->item->date;
 910
 911                         generation = commit_graph_generation(to_iter->item);
 912                         if (generation < min_generation)
 913                                 min_generation = generation;
 914                 }
 915
 916                 to_iter->item->object.flags |= PARENT2;
 917
 918                 to_iter = to_iter->next;
 919         }
 920
 921         result = can_all_from_reach_with_flag(&from_objs, PARENT2, PARENT1,
 922                                               min_commit_date, min_generation);
 923
 924         while (from) {
 925                 clear_commit_marks(from->item, PARENT1);
 926                 from = from->next;
 927         }
 928
 929         while (to) {
 930                 clear_commit_marks(to->item, PARENT2);
 931                 to = to->next;
 932         }
 933
 934         object_array_clear(&from_objs);
 935         return result;
 936 }
 937
 938 struct commit_list *get_reachable_subset(struct commit **from, int nr_from,
 939                                          struct commit **to, int nr_to,
 940                                          unsigned int reachable_flag)
 941 {
 942         struct commit **item;
 943         struct commit *current;
 944         struct commit_list *found_commits = NULL;
 945         struct commit **to_last = to + nr_to;
 946         struct commit **from_last = from + nr_from;
 947         timestamp_t min_generation = GENERATION_NUMBER_INFINITY;
 948         int num_to_find = 0;
 949
 950         struct prio_queue queue = { compare_commits_by_gen_then_commit_date };
 951
 952         for (item = to; item < to_last; item++) {
 953                 timestamp_t generation;
 954                 struct commit *c = *item;
 955
 956                 repo_parse_commit(the_repository, c);
 957                 generation = commit_graph_generation(c);
 958                 if (generation < min_generation)
 959                         min_generation = generation;
 960
 961                 if (!(c->object.flags & PARENT1)) {
 962                         c->object.flags |= PARENT1;
 963                         num_to_find++;
 964                 }
 965         }
 966
 967         for (item = from; item < from_last; item++) {
 968                 struct commit *c = *item;
 969                 if (!(c->object.flags & PARENT2)) {
 970                         c->object.flags |= PARENT2;
 971                         repo_parse_commit(the_repository, c);
 972
 973                         prio_queue_put(&queue, *item);
 974                 }
 975         }
 976
 977         while (num_to_find && (current = prio_queue_get(&queue)) != NULL) {
 978                 struct commit_list *parents;
 979
 980                 if (current->object.flags & PARENT1) {
 981                         current->object.flags &= ~PARENT1;
 982                         current->object.flags |= reachable_flag;
 983                         commit_list_insert(current, &found_commits);
 984                         num_to_find--;
 985                 }
 986
 987                 for (parents = current->parents; parents; parents = parents->next) {
 988                         struct commit *p = parents->item;
 989
 990                         repo_parse_commit(the_repository, p);
 991
 992                         if (commit_graph_generation(p) < min_generation)
 993                                 continue;
 994
 995                         if (p->object.flags & PARENT2)
 996                                 continue;
 997
 998                         p->object.flags |= PARENT2;
 999                         prio_queue_put(&queue, p);
1000                 }
1001         }
1002
1003         clear_prio_queue(&queue);
1004
1005         clear_commit_marks_many(nr_to, to, PARENT1);
1006         clear_commit_marks_many(nr_from, from, PARENT2);
1007
1008         return found_commits;
1009 }
1010
1011 define_commit_slab(bit_arrays, struct bitmap *);
1012 static struct bit_arrays bit_arrays;
1013
1014 static void insert_no_dup(struct prio_queue *queue, struct commit *c)
1015 {
1016         if (c->object.flags & PARENT2)
1017                 return;
1018         prio_queue_put(queue, c);
1019         c->object.flags |= PARENT2;
1020 }
1021
1022 static struct bitmap *get_bit_array(struct commit *c, int width)
1023 {
1024         struct bitmap **bitmap = bit_arrays_at(&bit_arrays, c);
1025         if (!*bitmap)
1026                 *bitmap = bitmap_word_alloc(width);
1027         return *bitmap;
1028 }
1029
1030 static void free_bit_array(struct commit *c)
1031 {
1032         struct bitmap **bitmap = bit_arrays_at(&bit_arrays, c);
1033         if (!*bitmap)
1034                 return;
1035         bitmap_free(*bitmap);
1036         *bitmap = NULL;
1037 }
1038
1039 void ahead_behind(struct repository *r,
1040                   struct commit **commits, size_t commits_nr,
1041                   struct ahead_behind_count *counts, size_t counts_nr)
1042 {
1043         struct prio_queue queue = { .compare = compare_commits_by_gen_then_commit_date };
1044         size_t width = DIV_ROUND_UP(commits_nr, BITS_IN_EWORD);
1045
1046         if (!commits_nr || !counts_nr)
1047                 return;
1048
1049         for (size_t i = 0; i < counts_nr; i++) {
1050                 counts[i].ahead = 0;
1051                 counts[i].behind = 0;
1052         }
1053
1054         ensure_generations_valid(r, commits, commits_nr);
1055
1056         init_bit_arrays(&bit_arrays);
1057
1058         for (size_t i = 0; i < commits_nr; i++) {
1059                 struct commit *c = commits[i];
1060                 struct bitmap *bitmap = get_bit_array(c, width);
1061
1062                 bitmap_set(bitmap, i);
1063                 insert_no_dup(&queue, c);
1064         }
1065
1066         while (queue_has_nonstale(&queue)) {
1067                 struct commit *c = prio_queue_get(&queue);
1068                 struct commit_list *p;
1069                 struct bitmap *bitmap_c = get_bit_array(c, width);
1070
1071                 for (size_t i = 0; i < counts_nr; i++) {
1072                         int reach_from_tip = !!bitmap_get(bitmap_c, counts[i].tip_index);
1073                         int reach_from_base = !!bitmap_get(bitmap_c, counts[i].base_index);
1074
1075                         if (reach_from_tip ^ reach_from_base) {
1076                                 if (reach_from_base)
1077                                         counts[i].behind++;
1078                                 else
1079                                         counts[i].ahead++;
1080                         }
1081                 }
1082
1083                 for (p = c->parents; p; p = p->next) {
1084                         struct bitmap *bitmap_p;
1085
1086                         repo_parse_commit(r, p->item);
1087
1088                         bitmap_p = get_bit_array(p->item, width);
1089                         bitmap_or(bitmap_p, bitmap_c);
1090
1091                         /*
1092                          * If this parent is reachable from every starting
1093                          * commit, then none of its ancestors can contribute
1094                          * to the ahead/behind count. Mark it as STALE, so
1095                          * we can stop the walk when every commit in the
1096                          * queue is STALE.
1097                          */
1098                         if (bitmap_popcount(bitmap_p) == commits_nr)
1099                                 p->item->object.flags |= STALE;
1100
1101                         insert_no_dup(&queue, p->item);
1102                 }
1103
1104                 free_bit_array(c);
1105         }
1106
1107         /* STALE is used here, PARENT2 is used by insert_no_dup(). */
1108         repo_clear_commit_marks(r, PARENT2 | STALE);
1109         clear_bit_arrays(&bit_arrays);
1110         clear_prio_queue(&queue);
1111 }
1112
1113 struct commit_and_index {
1114         struct commit *commit;
1115         unsigned int index;
1116         timestamp_t generation;
1117 };
1118
1119 static int compare_commit_and_index_by_generation(const void *va, const void *vb)
1120 {
1121         const struct commit_and_index *a = (const struct commit_and_index *)va;
1122         const struct commit_and_index *b = (const struct commit_and_index *)vb;
1123
1124         if (a->generation > b->generation)
1125                 return 1;
1126         if (a->generation < b->generation)
1127                 return -1;
1128         return 0;
1129 }
1130
1131 void tips_reachable_from_bases(struct repository *r,
1132                                struct commit_list *bases,
1133                                struct commit **tips, size_t tips_nr,
1134                                int mark)
1135 {
1136         struct commit_and_index *commits;
1137         size_t min_generation_index = 0;
1138         timestamp_t min_generation;
1139         struct commit_list *stack = NULL;
1140
1141         if (!bases || !tips || !tips_nr)
1142                 return;
1143
1144         /*
1145          * Do a depth-first search starting at 'bases' to search for the
1146          * tips. Stop at the lowest (un-found) generation number. When
1147          * finding the lowest commit, increase the minimum generation
1148          * number to the next lowest (un-found) generation number.
1149          */
1150
1151         CALLOC_ARRAY(commits, tips_nr);
1152
1153         for (size_t i = 0; i < tips_nr; i++) {
1154                 commits[i].commit = tips[i];
1155                 commits[i].index = i;
1156                 commits[i].generation = commit_graph_generation(tips[i]);
1157         }
1158
1159         /* Sort with generation number ascending. */
1160         QSORT(commits, tips_nr, compare_commit_and_index_by_generation);
1161         min_generation = commits[0].generation;
1162
1163         while (bases) {
1164                 repo_parse_commit(r, bases->item);
1165                 commit_list_insert(bases->item, &stack);
1166                 bases = bases->next;
1167         }
1168
1169         while (stack) {
1170                 int explored_all_parents = 1;
1171                 struct commit_list *p;
1172                 struct commit *c = stack->item;
1173                 timestamp_t c_gen = commit_graph_generation(c);
1174
1175                 /* Does it match any of our tips? */
1176                 for (size_t j = min_generation_index; j < tips_nr; j++) {
1177                         if (c_gen < commits[j].generation)
1178                                 break;
1179
1180                         if (commits[j].commit == c) {
1181                                 tips[commits[j].index]->object.flags |= mark;
1182
1183                                 if (j == min_generation_index) {
1184                                         unsigned int k = j + 1;
1185                                         while (k < tips_nr &&
1186                                                (tips[commits[k].index]->object.flags & mark))
1187                                                 k++;
1188
1189                                         /* Terminate early if all found. */
1190                                         if (k >= tips_nr)
1191                                                 goto done;
1192
1193                                         min_generation_index = k;
1194                                         min_generation = commits[k].generation;
1195                                 }
1196                         }
1197                 }
1198
1199                 for (p = c->parents; p; p = p->next) {
1200                         repo_parse_commit(r, p->item);
1201
1202                         /* Have we already explored this parent? */
1203                         if (p->item->object.flags & SEEN)
1204                                 continue;
1205
1206                         /* Is it below the current minimum generation? */
1207                         if (commit_graph_generation(p->item) < min_generation)
1208                                 continue;
1209
1210                         /* Ok, we will explore from here on. */
1211                         p->item->object.flags |= SEEN;
1212                         explored_all_parents = 0;
1213                         commit_list_insert(p->item, &stack);
1214                         break;
1215                 }
1216
1217                 if (explored_all_parents)
1218                         pop_commit(&stack);
1219         }
1220
1221 done:
1222         free(commits);
1223         repo_clear_commit_marks(r, SEEN);
1224 }