pack-bitmap-write.c

   1 #define USE_THE_REPOSITORY_VARIABLE
   2
   3 #include "git-compat-util.h"
   4 #include "environment.h"
   5 #include "gettext.h"
   6 #include "hex.h"
   7 #include "object-store-ll.h"
   8 #include "commit.h"
   9 #include "diff.h"
  10 #include "revision.h"
  11 #include "progress.h"
  12 #include "pack.h"
  13 #include "pack-bitmap.h"
  14 #include "hash-lookup.h"
  15 #include "pack-objects.h"
  16 #include "path.h"
  17 #include "commit-reach.h"
  18 #include "prio-queue.h"
  19 #include "trace2.h"
  20 #include "tree.h"
  21 #include "tree-walk.h"
  22 #include "pseudo-merge.h"
  23 #include "oid-array.h"
  24 #include "config.h"
  25 #include "alloc.h"
  26 #include "refs.h"
  27 #include "strmap.h"
  28
  29 struct bitmapped_commit {
  30         struct commit *commit;
  31         struct ewah_bitmap *bitmap;
  32         struct ewah_bitmap *write_as;
  33         int flags;
  34         int xor_offset;
  35         uint32_t commit_pos;
  36         unsigned pseudo_merge : 1;
  37 };
  38
  39 static inline int bitmap_writer_nr_selected_commits(struct bitmap_writer *writer)
  40 {
  41         return writer->selected_nr - writer->pseudo_merges_nr;
  42 }
  43
  44 void bitmap_writer_init(struct bitmap_writer *writer, struct repository *r,
  45                         struct packing_data *pdata)
  46 {
  47         memset(writer, 0, sizeof(struct bitmap_writer));
  48         if (writer->bitmaps)
  49                 BUG("bitmap writer already initialized");
  50         writer->bitmaps = kh_init_oid_map();
  51         writer->pseudo_merge_commits = kh_init_oid_map();
  52         writer->to_pack = pdata;
  53
  54         string_list_init_dup(&writer->pseudo_merge_groups);
  55
  56         load_pseudo_merges_from_config(r, &writer->pseudo_merge_groups);
  57 }
  58
  59 static void free_pseudo_merge_commit_idx(struct pseudo_merge_commit_idx *idx)
  60 {
  61         if (!idx)
  62                 return;
  63         free(idx->pseudo_merge);
  64         free(idx);
  65 }
  66
  67 void bitmap_writer_free(struct bitmap_writer *writer)
  68 {
  69         uint32_t i;
  70         struct pseudo_merge_commit_idx *idx;
  71
  72         if (!writer)
  73                 return;
  74
  75         ewah_free(writer->commits);
  76         ewah_free(writer->trees);
  77         ewah_free(writer->blobs);
  78         ewah_free(writer->tags);
  79
  80         kh_destroy_oid_map(writer->bitmaps);
  81
  82         kh_foreach_value(writer->pseudo_merge_commits, idx,
  83                          free_pseudo_merge_commit_idx(idx));
  84         kh_destroy_oid_map(writer->pseudo_merge_commits);
  85
  86         for (i = 0; i < writer->selected_nr; i++) {
  87                 struct bitmapped_commit *bc = &writer->selected[i];
  88                 if (bc->write_as != bc->bitmap)
  89                         ewah_free(bc->write_as);
  90                 ewah_free(bc->bitmap);
  91         }
  92         free(writer->selected);
  93 }
  94
  95 void bitmap_writer_show_progress(struct bitmap_writer *writer, int show)
  96 {
  97         writer->show_progress = show;
  98 }
  99
 100 /**
 101  * Build the initial type index for the packfile or multi-pack-index
 102  */
 103 void bitmap_writer_build_type_index(struct bitmap_writer *writer,
 104                                     struct pack_idx_entry **index)
 105 {
 106         uint32_t i;
 107
 108         writer->commits = ewah_new();
 109         writer->trees = ewah_new();
 110         writer->blobs = ewah_new();
 111         writer->tags = ewah_new();
 112         ALLOC_ARRAY(writer->to_pack->in_pack_pos, writer->to_pack->nr_objects);
 113
 114         for (i = 0; i < writer->to_pack->nr_objects; ++i) {
 115                 struct object_entry *entry = (struct object_entry *)index[i];
 116                 enum object_type real_type;
 117
 118                 oe_set_in_pack_pos(writer->to_pack, entry, i);
 119
 120                 switch (oe_type(entry)) {
 121                 case OBJ_COMMIT:
 122                 case OBJ_TREE:
 123                 case OBJ_BLOB:
 124                 case OBJ_TAG:
 125                         real_type = oe_type(entry);
 126                         break;
 127
 128                 default:
 129                         real_type = oid_object_info(writer->to_pack->repo,
 130                                                     &entry->idx.oid, NULL);
 131                         break;
 132                 }
 133
 134                 switch (real_type) {
 135                 case OBJ_COMMIT:
 136                         ewah_set(writer->commits, i);
 137                         break;
 138
 139                 case OBJ_TREE:
 140                         ewah_set(writer->trees, i);
 141                         break;
 142
 143                 case OBJ_BLOB:
 144                         ewah_set(writer->blobs, i);
 145                         break;
 146
 147                 case OBJ_TAG:
 148                         ewah_set(writer->tags, i);
 149                         break;
 150
 151                 default:
 152                         die("Missing type information for %s (%d/%d)",
 153                             oid_to_hex(&entry->idx.oid), real_type,
 154                             oe_type(entry));
 155                 }
 156         }
 157 }
 158
 159 int bitmap_writer_has_bitmapped_object_id(struct bitmap_writer *writer,
 160                                           const struct object_id *oid)
 161 {
 162         return kh_get_oid_map(writer->bitmaps, *oid) != kh_end(writer->bitmaps);
 163 }
 164
 165 /**
 166  * Compute the actual bitmaps
 167  */
 168
 169 void bitmap_writer_push_commit(struct bitmap_writer *writer,
 170                                struct commit *commit, unsigned pseudo_merge)
 171 {
 172         if (writer->selected_nr >= writer->selected_alloc) {
 173                 writer->selected_alloc = (writer->selected_alloc + 32) * 2;
 174                 REALLOC_ARRAY(writer->selected, writer->selected_alloc);
 175         }
 176
 177         if (!pseudo_merge) {
 178                 int hash_ret;
 179                 khiter_t hash_pos = kh_put_oid_map(writer->bitmaps,
 180                                                    commit->object.oid,
 181                                                    &hash_ret);
 182
 183                 if (!hash_ret)
 184                         die(_("duplicate entry when writing bitmap index: %s"),
 185                             oid_to_hex(&commit->object.oid));
 186                 kh_value(writer->bitmaps, hash_pos) = NULL;
 187         }
 188
 189         writer->selected[writer->selected_nr].commit = commit;
 190         writer->selected[writer->selected_nr].bitmap = NULL;
 191         writer->selected[writer->selected_nr].write_as = NULL;
 192         writer->selected[writer->selected_nr].flags = 0;
 193         writer->selected[writer->selected_nr].pseudo_merge = pseudo_merge;
 194
 195         writer->selected_nr++;
 196 }
 197
 198 static uint32_t find_object_pos(struct bitmap_writer *writer,
 199                                 const struct object_id *oid, int *found)
 200 {
 201         struct object_entry *entry = packlist_find(writer->to_pack, oid);
 202
 203         if (!entry) {
 204                 if (found)
 205                         *found = 0;
 206                 warning("Failed to write bitmap index. Packfile doesn't have full closure "
 207                         "(object %s is missing)", oid_to_hex(oid));
 208                 return 0;
 209         }
 210
 211         if (found)
 212                 *found = 1;
 213         return oe_in_pack_pos(writer->to_pack, entry);
 214 }
 215
 216 static void compute_xor_offsets(struct bitmap_writer *writer)
 217 {
 218         static const int MAX_XOR_OFFSET_SEARCH = 10;
 219
 220         int i, next = 0;
 221
 222         while (next < writer->selected_nr) {
 223                 struct bitmapped_commit *stored = &writer->selected[next];
 224                 int best_offset = 0;
 225                 struct ewah_bitmap *best_bitmap = stored->bitmap;
 226                 struct ewah_bitmap *test_xor;
 227
 228                 if (stored->pseudo_merge)
 229                         goto next;
 230
 231                 for (i = 1; i <= MAX_XOR_OFFSET_SEARCH; ++i) {
 232                         int curr = next - i;
 233
 234                         if (curr < 0)
 235                                 break;
 236                         if (writer->selected[curr].pseudo_merge)
 237                                 continue;
 238
 239                         test_xor = ewah_pool_new();
 240                         ewah_xor(writer->selected[curr].bitmap, stored->bitmap, test_xor);
 241
 242                         if (test_xor->buffer_size < best_bitmap->buffer_size) {
 243                                 if (best_bitmap != stored->bitmap)
 244                                         ewah_pool_free(best_bitmap);
 245
 246                                 best_bitmap = test_xor;
 247                                 best_offset = i;
 248                         } else {
 249                                 ewah_pool_free(test_xor);
 250                         }
 251                 }
 252
 253 next:
 254                 stored->xor_offset = best_offset;
 255                 stored->write_as = best_bitmap;
 256
 257                 next++;
 258         }
 259 }
 260
 261 struct bb_commit {
 262         struct commit_list *reverse_edges;
 263         struct bitmap *commit_mask;
 264         struct bitmap *bitmap;
 265         unsigned selected:1,
 266                  maximal:1,
 267                  pseudo_merge:1;
 268         unsigned idx; /* within selected array */
 269 };
 270
 271 static void clear_bb_commit(struct bb_commit *commit)
 272 {
 273         free_commit_list(commit->reverse_edges);
 274         bitmap_free(commit->commit_mask);
 275         bitmap_free(commit->bitmap);
 276 }
 277
 278 define_commit_slab(bb_data, struct bb_commit);
 279
 280 struct bitmap_builder {
 281         struct bb_data data;
 282         struct commit **commits;
 283         size_t commits_nr, commits_alloc;
 284 };
 285
 286 static void bitmap_builder_init(struct bitmap_builder *bb,
 287                                 struct bitmap_writer *writer,
 288                                 struct bitmap_index *old_bitmap)
 289 {
 290         struct rev_info revs;
 291         struct commit *commit;
 292         struct commit_list *reusable = NULL;
 293         struct commit_list *r;
 294         unsigned int i, num_maximal = 0;
 295
 296         memset(bb, 0, sizeof(*bb));
 297         init_bb_data(&bb->data);
 298
 299         reset_revision_walk();
 300         repo_init_revisions(writer->to_pack->repo, &revs, NULL);
 301         revs.topo_order = 1;
 302         revs.first_parent_only = 1;
 303
 304         for (i = 0; i < writer->selected_nr; i++) {
 305                 struct bitmapped_commit *bc = &writer->selected[i];
 306                 struct bb_commit *ent = bb_data_at(&bb->data, bc->commit);
 307
 308                 ent->selected = 1;
 309                 ent->maximal = 1;
 310                 ent->pseudo_merge = bc->pseudo_merge;
 311                 ent->idx = i;
 312
 313                 ent->commit_mask = bitmap_new();
 314                 bitmap_set(ent->commit_mask, i);
 315
 316                 add_pending_object(&revs, &bc->commit->object, "");
 317         }
 318
 319         if (prepare_revision_walk(&revs))
 320                 die("revision walk setup failed");
 321
 322         while ((commit = get_revision(&revs))) {
 323                 struct commit_list *p = commit->parents;
 324                 struct bb_commit *c_ent;
 325
 326                 parse_commit_or_die(commit);
 327
 328                 c_ent = bb_data_at(&bb->data, commit);
 329
 330                 /*
 331                  * If there is no commit_mask, there is no reason to iterate
 332                  * over this commit; it is not selected (if it were, it would
 333                  * not have a blank commit mask) and all its children have
 334                  * existing bitmaps (see the comment starting with "This commit
 335                  * has an existing bitmap" below), so it does not contribute
 336                  * anything to the final bitmap file or its descendants.
 337                  */
 338                 if (!c_ent->commit_mask)
 339                         continue;
 340
 341                 if (old_bitmap && bitmap_for_commit(old_bitmap, commit)) {
 342                         /*
 343                          * This commit has an existing bitmap, so we can
 344                          * get its bits immediately without an object
 345                          * walk. That is, it is reusable as-is and there is no
 346                          * need to continue walking beyond it.
 347                          *
 348                          * Mark it as such and add it to bb->commits separately
 349                          * to avoid allocating a position in the commit mask.
 350                          */
 351                         commit_list_insert(commit, &reusable);
 352                         goto next;
 353                 }
 354
 355                 if (c_ent->maximal) {
 356                         num_maximal++;
 357                         ALLOC_GROW(bb->commits, bb->commits_nr + 1, bb->commits_alloc);
 358                         bb->commits[bb->commits_nr++] = commit;
 359                 }
 360
 361                 if (p) {
 362                         struct bb_commit *p_ent = bb_data_at(&bb->data, p->item);
 363                         int c_not_p, p_not_c;
 364
 365                         if (!p_ent->commit_mask) {
 366                                 p_ent->commit_mask = bitmap_new();
 367                                 c_not_p = 1;
 368                                 p_not_c = 0;
 369                         } else {
 370                                 c_not_p = bitmap_is_subset(c_ent->commit_mask, p_ent->commit_mask);
 371                                 p_not_c = bitmap_is_subset(p_ent->commit_mask, c_ent->commit_mask);
 372                         }
 373
 374                         if (!c_not_p)
 375                                 continue;
 376
 377                         bitmap_or(p_ent->commit_mask, c_ent->commit_mask);
 378
 379                         if (p_not_c)
 380                                 p_ent->maximal = 1;
 381                         else {
 382                                 p_ent->maximal = 0;
 383                                 free_commit_list(p_ent->reverse_edges);
 384                                 p_ent->reverse_edges = NULL;
 385                         }
 386
 387                         if (c_ent->maximal) {
 388                                 commit_list_insert(commit, &p_ent->reverse_edges);
 389                         } else {
 390                                 struct commit_list *cc = c_ent->reverse_edges;
 391
 392                                 for (; cc; cc = cc->next) {
 393                                         if (!commit_list_contains(cc->item, p_ent->reverse_edges))
 394                                                 commit_list_insert(cc->item, &p_ent->reverse_edges);
 395                                 }
 396                         }
 397                 }
 398
 399 next:
 400                 bitmap_free(c_ent->commit_mask);
 401                 c_ent->commit_mask = NULL;
 402         }
 403
 404         for (r = reusable; r; r = r->next) {
 405                 ALLOC_GROW(bb->commits, bb->commits_nr + 1, bb->commits_alloc);
 406                 bb->commits[bb->commits_nr++] = r->item;
 407         }
 408
 409         trace2_data_intmax("pack-bitmap-write", the_repository,
 410                            "num_selected_commits", writer->selected_nr);
 411         trace2_data_intmax("pack-bitmap-write", the_repository,
 412                            "num_maximal_commits", num_maximal);
 413
 414         release_revisions(&revs);
 415         free_commit_list(reusable);
 416 }
 417
 418 static void bitmap_builder_clear(struct bitmap_builder *bb)
 419 {
 420         deep_clear_bb_data(&bb->data, clear_bb_commit);
 421         free(bb->commits);
 422         bb->commits_nr = bb->commits_alloc = 0;
 423 }
 424
 425 static int fill_bitmap_tree(struct bitmap_writer *writer,
 426                             struct bitmap *bitmap,
 427                             struct tree *tree)
 428 {
 429         int found;
 430         uint32_t pos;
 431         struct tree_desc desc;
 432         struct name_entry entry;
 433
 434         /*
 435          * If our bit is already set, then there is nothing to do. Both this
 436          * tree and all of its children will be set.
 437          */
 438         pos = find_object_pos(writer, &tree->object.oid, &found);
 439         if (!found)
 440                 return -1;
 441         if (bitmap_get(bitmap, pos))
 442                 return 0;
 443         bitmap_set(bitmap, pos);
 444
 445         if (parse_tree(tree) < 0)
 446                 die("unable to load tree object %s",
 447                     oid_to_hex(&tree->object.oid));
 448         init_tree_desc(&desc, &tree->object.oid, tree->buffer, tree->size);
 449
 450         while (tree_entry(&desc, &entry)) {
 451                 switch (object_type(entry.mode)) {
 452                 case OBJ_TREE:
 453                         if (fill_bitmap_tree(writer, bitmap,
 454                                              lookup_tree(the_repository, &entry.oid)) < 0)
 455                                 return -1;
 456                         break;
 457                 case OBJ_BLOB:
 458                         pos = find_object_pos(writer, &entry.oid, &found);
 459                         if (!found)
 460                                 return -1;
 461                         bitmap_set(bitmap, pos);
 462                         break;
 463                 default:
 464                         /* Gitlink, etc; not reachable */
 465                         break;
 466                 }
 467         }
 468
 469         free_tree_buffer(tree);
 470         return 0;
 471 }
 472
 473 static int reused_bitmaps_nr;
 474 static int reused_pseudo_merge_bitmaps_nr;
 475
 476 static int fill_bitmap_commit(struct bitmap_writer *writer,
 477                               struct bb_commit *ent,
 478                               struct commit *commit,
 479                               struct prio_queue *queue,
 480                               struct prio_queue *tree_queue,
 481                               struct bitmap_index *old_bitmap,
 482                               const uint32_t *mapping)
 483 {
 484         int found;
 485         uint32_t pos;
 486         if (!ent->bitmap)
 487                 ent->bitmap = bitmap_new();
 488
 489         prio_queue_put(queue, commit);
 490
 491         while (queue->nr) {
 492                 struct commit_list *p;
 493                 struct commit *c = prio_queue_get(queue);
 494
 495                 if (old_bitmap && mapping) {
 496                         struct ewah_bitmap *old;
 497                         struct bitmap *remapped = bitmap_new();
 498
 499                         if (commit->object.flags & BITMAP_PSEUDO_MERGE)
 500                                 old = pseudo_merge_bitmap_for_commit(old_bitmap, c);
 501                         else
 502                                 old = bitmap_for_commit(old_bitmap, c);
 503                         /*
 504                          * If this commit has an old bitmap, then translate that
 505                          * bitmap and add its bits to this one. No need to walk
 506                          * parents or the tree for this commit.
 507                          */
 508                         if (old && !rebuild_bitmap(mapping, old, remapped)) {
 509                                 bitmap_or(ent->bitmap, remapped);
 510                                 bitmap_free(remapped);
 511                                 if (commit->object.flags & BITMAP_PSEUDO_MERGE)
 512                                         reused_pseudo_merge_bitmaps_nr++;
 513                                 else
 514                                         reused_bitmaps_nr++;
 515                                 continue;
 516                         }
 517                         bitmap_free(remapped);
 518                 }
 519
 520                 /*
 521                  * Mark ourselves and queue our tree. The commit
 522                  * walk ensures we cover all parents.
 523                  */
 524                 if (!(c->object.flags & BITMAP_PSEUDO_MERGE)) {
 525                         pos = find_object_pos(writer, &c->object.oid, &found);
 526                         if (!found)
 527                                 return -1;
 528                         bitmap_set(ent->bitmap, pos);
 529                         prio_queue_put(tree_queue,
 530                                        repo_get_commit_tree(the_repository, c));
 531                 }
 532
 533                 for (p = c->parents; p; p = p->next) {
 534                         pos = find_object_pos(writer, &p->item->object.oid,
 535                                               &found);
 536                         if (!found)
 537                                 return -1;
 538                         if (!bitmap_get(ent->bitmap, pos)) {
 539                                 bitmap_set(ent->bitmap, pos);
 540                                 prio_queue_put(queue, p->item);
 541                         }
 542                 }
 543         }
 544
 545         while (tree_queue->nr) {
 546                 if (fill_bitmap_tree(writer, ent->bitmap,
 547                                      prio_queue_get(tree_queue)) < 0)
 548                         return -1;
 549         }
 550         return 0;
 551 }
 552
 553 static void store_selected(struct bitmap_writer *writer,
 554                            struct bb_commit *ent, struct commit *commit)
 555 {
 556         struct bitmapped_commit *stored = &writer->selected[ent->idx];
 557         khiter_t hash_pos;
 558
 559         stored->bitmap = bitmap_to_ewah(ent->bitmap);
 560
 561         if (ent->pseudo_merge)
 562                 return;
 563
 564         hash_pos = kh_get_oid_map(writer->bitmaps, commit->object.oid);
 565         if (hash_pos == kh_end(writer->bitmaps))
 566                 die(_("attempted to store non-selected commit: '%s'"),
 567                     oid_to_hex(&commit->object.oid));
 568
 569         kh_value(writer->bitmaps, hash_pos) = stored;
 570 }
 571
 572 int bitmap_writer_build(struct bitmap_writer *writer)
 573 {
 574         struct bitmap_builder bb;
 575         size_t i;
 576         int nr_stored = 0; /* for progress */
 577         struct prio_queue queue = { compare_commits_by_gen_then_commit_date };
 578         struct prio_queue tree_queue = { NULL };
 579         struct bitmap_index *old_bitmap;
 580         uint32_t *mapping;
 581         int closed = 1; /* until proven otherwise */
 582
 583         if (writer->show_progress)
 584                 writer->progress = start_progress("Building bitmaps",
 585                                                   writer->selected_nr);
 586         trace2_region_enter("pack-bitmap-write", "building_bitmaps_total",
 587                             the_repository);
 588
 589         old_bitmap = prepare_bitmap_git(writer->to_pack->repo);
 590         if (old_bitmap)
 591                 mapping = create_bitmap_mapping(old_bitmap, writer->to_pack);
 592         else
 593                 mapping = NULL;
 594
 595         bitmap_builder_init(&bb, writer, old_bitmap);
 596         for (i = bb.commits_nr; i > 0; i--) {
 597                 struct commit *commit = bb.commits[i-1];
 598                 struct bb_commit *ent = bb_data_at(&bb.data, commit);
 599                 struct commit *child;
 600                 int reused = 0;
 601
 602                 if (fill_bitmap_commit(writer, ent, commit, &queue, &tree_queue,
 603                                        old_bitmap, mapping) < 0) {
 604                         closed = 0;
 605                         break;
 606                 }
 607
 608                 if (ent->selected) {
 609                         store_selected(writer, ent, commit);
 610                         nr_stored++;
 611                         display_progress(writer->progress, nr_stored);
 612                 }
 613
 614                 while ((child = pop_commit(&ent->reverse_edges))) {
 615                         struct bb_commit *child_ent =
 616                                 bb_data_at(&bb.data, child);
 617
 618                         if (child_ent->bitmap)
 619                                 bitmap_or(child_ent->bitmap, ent->bitmap);
 620                         else if (reused)
 621                                 child_ent->bitmap = bitmap_dup(ent->bitmap);
 622                         else {
 623                                 child_ent->bitmap = ent->bitmap;
 624                                 reused = 1;
 625                         }
 626                 }
 627                 if (!reused)
 628                         bitmap_free(ent->bitmap);
 629                 ent->bitmap = NULL;
 630         }
 631         clear_prio_queue(&queue);
 632         clear_prio_queue(&tree_queue);
 633         bitmap_builder_clear(&bb);
 634         free_bitmap_index(old_bitmap);
 635         free(mapping);
 636
 637         trace2_region_leave("pack-bitmap-write", "building_bitmaps_total",
 638                             the_repository);
 639         trace2_data_intmax("pack-bitmap-write", the_repository,
 640                            "building_bitmaps_reused", reused_bitmaps_nr);
 641         trace2_data_intmax("pack-bitmap-write", the_repository,
 642                            "building_bitmaps_pseudo_merge_reused",
 643                            reused_pseudo_merge_bitmaps_nr);
 644
 645         stop_progress(&writer->progress);
 646
 647         if (closed)
 648                 compute_xor_offsets(writer);
 649         return closed ? 0 : -1;
 650 }
 651
 652 /**
 653  * Select the commits that will be bitmapped
 654  */
 655 static inline unsigned int next_commit_index(unsigned int idx)
 656 {
 657         static const unsigned int MIN_COMMITS = 100;
 658         static const unsigned int MAX_COMMITS = 5000;
 659
 660         static const unsigned int MUST_REGION = 100;
 661         static const unsigned int MIN_REGION = 20000;
 662
 663         unsigned int offset, next;
 664
 665         if (idx <= MUST_REGION)
 666                 return 0;
 667
 668         if (idx <= MIN_REGION) {
 669                 offset = idx - MUST_REGION;
 670                 return (offset < MIN_COMMITS) ? offset : MIN_COMMITS;
 671         }
 672
 673         offset = idx - MIN_REGION;
 674         next = (offset < MAX_COMMITS) ? offset : MAX_COMMITS;
 675
 676         return (next > MIN_COMMITS) ? next : MIN_COMMITS;
 677 }
 678
 679 static int date_compare(const void *_a, const void *_b)
 680 {
 681         struct commit *a = *(struct commit **)_a;
 682         struct commit *b = *(struct commit **)_b;
 683         return (long)b->date - (long)a->date;
 684 }
 685
 686 void bitmap_writer_select_commits(struct bitmap_writer *writer,
 687                                   struct commit **indexed_commits,
 688                                   unsigned int indexed_commits_nr)
 689 {
 690         unsigned int i = 0, j, next;
 691
 692         QSORT(indexed_commits, indexed_commits_nr, date_compare);
 693
 694         if (indexed_commits_nr < 100) {
 695                 for (i = 0; i < indexed_commits_nr; ++i)
 696                         bitmap_writer_push_commit(writer, indexed_commits[i], 0);
 697
 698                 select_pseudo_merges(writer);
 699
 700                 return;
 701         }
 702
 703         if (writer->show_progress)
 704                 writer->progress = start_progress("Selecting bitmap commits", 0);
 705
 706         for (;;) {
 707                 struct commit *chosen = NULL;
 708
 709                 next = next_commit_index(i);
 710
 711                 if (i + next >= indexed_commits_nr)
 712                         break;
 713
 714                 if (next == 0) {
 715                         chosen = indexed_commits[i];
 716                 } else {
 717                         chosen = indexed_commits[i + next];
 718
 719                         for (j = 0; j <= next; ++j) {
 720                                 struct commit *cm = indexed_commits[i + j];
 721
 722                                 if ((cm->object.flags & NEEDS_BITMAP) != 0) {
 723                                         chosen = cm;
 724                                         break;
 725                                 }
 726
 727                                 if (cm->parents && cm->parents->next)
 728                                         chosen = cm;
 729                         }
 730                 }
 731
 732                 bitmap_writer_push_commit(writer, chosen, 0);
 733
 734                 i += next + 1;
 735                 display_progress(writer->progress, i);
 736         }
 737
 738         stop_progress(&writer->progress);
 739
 740         select_pseudo_merges(writer);
 741 }
 742
 743
 744 static int hashwrite_ewah_helper(void *f, const void *buf, size_t len)
 745 {
 746         /* hashwrite will die on error */
 747         hashwrite(f, buf, len);
 748         return len;
 749 }
 750
 751 /**
 752  * Write the bitmap index to disk
 753  */
 754 static inline void dump_bitmap(struct hashfile *f, struct ewah_bitmap *bitmap)
 755 {
 756         if (ewah_serialize_to(bitmap, hashwrite_ewah_helper, f) < 0)
 757                 die("Failed to write bitmap index");
 758 }
 759
 760 static const struct object_id *oid_access(size_t pos, const void *table)
 761 {
 762         const struct pack_idx_entry * const *index = table;
 763         return &index[pos]->oid;
 764 }
 765
 766 static void write_selected_commits_v1(struct bitmap_writer *writer,
 767                                       struct hashfile *f, off_t *offsets)
 768 {
 769         int i;
 770
 771         for (i = 0; i < bitmap_writer_nr_selected_commits(writer); ++i) {
 772                 struct bitmapped_commit *stored = &writer->selected[i];
 773                 if (stored->pseudo_merge)
 774                         BUG("unexpected pseudo-merge among selected: %s",
 775                             oid_to_hex(&stored->commit->object.oid));
 776
 777                 if (offsets)
 778                         offsets[i] = hashfile_total(f);
 779
 780                 hashwrite_be32(f, stored->commit_pos);
 781                 hashwrite_u8(f, stored->xor_offset);
 782                 hashwrite_u8(f, stored->flags);
 783
 784                 dump_bitmap(f, stored->write_as);
 785         }
 786 }
 787
 788 static void write_pseudo_merges(struct bitmap_writer *writer,
 789                                 struct hashfile *f)
 790 {
 791         struct oid_array commits = OID_ARRAY_INIT;
 792         struct bitmap **commits_bitmap = NULL;
 793         off_t *pseudo_merge_ofs = NULL;
 794         off_t start, table_start, next_ext;
 795
 796         uint32_t base = bitmap_writer_nr_selected_commits(writer);
 797         size_t i, j = 0;
 798
 799         CALLOC_ARRAY(commits_bitmap, writer->pseudo_merges_nr);
 800         CALLOC_ARRAY(pseudo_merge_ofs, writer->pseudo_merges_nr);
 801
 802         for (i = 0; i < writer->pseudo_merges_nr; i++) {
 803                 struct bitmapped_commit *merge = &writer->selected[base + i];
 804                 struct commit_list *p;
 805
 806                 if (!merge->pseudo_merge)
 807                         BUG("found non-pseudo merge commit at %"PRIuMAX, (uintmax_t)i);
 808
 809                 commits_bitmap[i] = bitmap_new();
 810
 811                 for (p = merge->commit->parents; p; p = p->next)
 812                         bitmap_set(commits_bitmap[i],
 813                                    find_object_pos(writer, &p->item->object.oid,
 814                                                    NULL));
 815         }
 816
 817         start = hashfile_total(f);
 818
 819         for (i = 0; i < writer->pseudo_merges_nr; i++) {
 820                 struct ewah_bitmap *commits_ewah = bitmap_to_ewah(commits_bitmap[i]);
 821
 822                 pseudo_merge_ofs[i] = hashfile_total(f);
 823
 824                 dump_bitmap(f, commits_ewah);
 825                 dump_bitmap(f, writer->selected[base+i].write_as);
 826
 827                 ewah_free(commits_ewah);
 828         }
 829
 830         next_ext = st_add(hashfile_total(f),
 831                           st_mult(kh_size(writer->pseudo_merge_commits),
 832                                   sizeof(uint64_t)));
 833
 834         table_start = hashfile_total(f);
 835
 836         commits.alloc = kh_size(writer->pseudo_merge_commits);
 837         CALLOC_ARRAY(commits.oid, commits.alloc);
 838
 839         for (i = kh_begin(writer->pseudo_merge_commits); i != kh_end(writer->pseudo_merge_commits); i++) {
 840                 if (!kh_exist(writer->pseudo_merge_commits, i))
 841                         continue;
 842                 oid_array_append(&commits, &kh_key(writer->pseudo_merge_commits, i));
 843         }
 844
 845         oid_array_sort(&commits);
 846
 847         /* write lookup table (non-extended) */
 848         for (i = 0; i < commits.nr; i++) {
 849                 int hash_pos;
 850                 struct pseudo_merge_commit_idx *c;
 851
 852                 hash_pos = kh_get_oid_map(writer->pseudo_merge_commits,
 853                                           commits.oid[i]);
 854                 if (hash_pos == kh_end(writer->pseudo_merge_commits))
 855                         BUG("could not find pseudo-merge commit %s",
 856                             oid_to_hex(&commits.oid[i]));
 857
 858                 c = kh_value(writer->pseudo_merge_commits, hash_pos);
 859
 860                 hashwrite_be32(f, find_object_pos(writer, &commits.oid[i],
 861                                                   NULL));
 862                 if (c->nr == 1)
 863                         hashwrite_be64(f, pseudo_merge_ofs[c->pseudo_merge[0]]);
 864                 else if (c->nr > 1) {
 865                         if (next_ext & ((uint64_t)1<<63))
 866                                 die(_("too many pseudo-merges"));
 867                         hashwrite_be64(f, next_ext | ((uint64_t)1<<63));
 868                         next_ext = st_add3(next_ext,
 869                                            sizeof(uint32_t),
 870                                            st_mult(c->nr, sizeof(uint64_t)));
 871                 } else
 872                         BUG("expected commit '%s' to have at least one "
 873                             "pseudo-merge", oid_to_hex(&commits.oid[i]));
 874         }
 875
 876         /* write lookup table (extended) */
 877         for (i = 0; i < commits.nr; i++) {
 878                 int hash_pos;
 879                 struct pseudo_merge_commit_idx *c;
 880
 881                 hash_pos = kh_get_oid_map(writer->pseudo_merge_commits,
 882                                           commits.oid[i]);
 883                 if (hash_pos == kh_end(writer->pseudo_merge_commits))
 884                         BUG("could not find pseudo-merge commit %s",
 885                             oid_to_hex(&commits.oid[i]));
 886
 887                 c = kh_value(writer->pseudo_merge_commits, hash_pos);
 888                 if (c->nr == 1)
 889                         continue;
 890
 891                 hashwrite_be32(f, c->nr);
 892                 for (j = 0; j < c->nr; j++)
 893                         hashwrite_be64(f, pseudo_merge_ofs[c->pseudo_merge[j]]);
 894         }
 895
 896         /* write positions for all pseudo merges */
 897         for (i = 0; i < writer->pseudo_merges_nr; i++)
 898                 hashwrite_be64(f, pseudo_merge_ofs[i]);
 899
 900         hashwrite_be32(f, writer->pseudo_merges_nr);
 901         hashwrite_be32(f, kh_size(writer->pseudo_merge_commits));
 902         hashwrite_be64(f, table_start - start);
 903         hashwrite_be64(f, hashfile_total(f) - start + sizeof(uint64_t));
 904
 905         for (i = 0; i < writer->pseudo_merges_nr; i++)
 906                 bitmap_free(commits_bitmap[i]);
 907
 908         free(pseudo_merge_ofs);
 909         free(commits_bitmap);
 910 }
 911
 912 static int table_cmp(const void *_va, const void *_vb, void *_data)
 913 {
 914         struct bitmap_writer *writer = _data;
 915         struct bitmapped_commit *a = &writer->selected[*(uint32_t *)_va];
 916         struct bitmapped_commit *b = &writer->selected[*(uint32_t *)_vb];
 917
 918         if (a->commit_pos < b->commit_pos)
 919                 return -1;
 920         else if (a->commit_pos > b->commit_pos)
 921                 return 1;
 922
 923         return 0;
 924 }
 925
 926 static void write_lookup_table(struct bitmap_writer *writer, struct hashfile *f,
 927                                off_t *offsets)
 928 {
 929         uint32_t i;
 930         uint32_t *table, *table_inv;
 931
 932         ALLOC_ARRAY(table, bitmap_writer_nr_selected_commits(writer));
 933         ALLOC_ARRAY(table_inv, bitmap_writer_nr_selected_commits(writer));
 934
 935         for (i = 0; i < bitmap_writer_nr_selected_commits(writer); i++)
 936                 table[i] = i;
 937
 938         /*
 939          * At the end of this sort table[j] = i means that the i'th
 940          * bitmap corresponds to j'th bitmapped commit (among the selected
 941          * commits) in lex order of OIDs.
 942          */
 943         QSORT_S(table, bitmap_writer_nr_selected_commits(writer), table_cmp, writer);
 944
 945         /* table_inv helps us discover that relationship (i'th bitmap
 946          * to j'th commit by j = table_inv[i])
 947          */
 948         for (i = 0; i < bitmap_writer_nr_selected_commits(writer); i++)
 949                 table_inv[table[i]] = i;
 950
 951         trace2_region_enter("pack-bitmap-write", "writing_lookup_table", the_repository);
 952         for (i = 0; i < bitmap_writer_nr_selected_commits(writer); i++) {
 953                 struct bitmapped_commit *selected = &writer->selected[table[i]];
 954                 uint32_t xor_offset = selected->xor_offset;
 955                 uint32_t xor_row;
 956
 957                 if (xor_offset) {
 958                         /*
 959                          * xor_index stores the index (in the bitmap entries)
 960                          * of the corresponding xor bitmap. But we need to convert
 961                          * this index into lookup table's index. So, table_inv[xor_index]
 962                          * gives us the index position w.r.t. the lookup table.
 963                          *
 964                          * If "k = table[i] - xor_offset" then the xor base is the k'th
 965                          * bitmap. `table_inv[k]` gives us the position of that bitmap
 966                          * in the lookup table.
 967                          */
 968                         uint32_t xor_index = table[i] - xor_offset;
 969                         xor_row = table_inv[xor_index];
 970                 } else {
 971                         xor_row = 0xffffffff;
 972                 }
 973
 974                 hashwrite_be32(f, writer->selected[table[i]].commit_pos);
 975                 hashwrite_be64(f, (uint64_t)offsets[table[i]]);
 976                 hashwrite_be32(f, xor_row);
 977         }
 978         trace2_region_leave("pack-bitmap-write", "writing_lookup_table", the_repository);
 979
 980         free(table);
 981         free(table_inv);
 982 }
 983
 984 static void write_hash_cache(struct hashfile *f,
 985                              struct pack_idx_entry **index,
 986                              uint32_t index_nr)
 987 {
 988         uint32_t i;
 989
 990         for (i = 0; i < index_nr; ++i) {
 991                 struct object_entry *entry = (struct object_entry *)index[i];
 992                 hashwrite_be32(f, entry->hash);
 993         }
 994 }
 995
 996 void bitmap_writer_set_checksum(struct bitmap_writer *writer,
 997                                 const unsigned char *sha1)
 998 {
 999         hashcpy(writer->pack_checksum, sha1, the_repository->hash_algo);
1000 }
1001
1002 void bitmap_writer_finish(struct bitmap_writer *writer,
1003                           struct pack_idx_entry **index,
1004                           const char *filename,
1005                           uint16_t options)
1006 {
1007         static uint16_t default_version = 1;
1008         static uint16_t flags = BITMAP_OPT_FULL_DAG;
1009         struct strbuf tmp_file = STRBUF_INIT;
1010         struct hashfile *f;
1011         off_t *offsets = NULL;
1012         uint32_t i;
1013
1014         struct bitmap_disk_header header;
1015
1016         int fd = odb_mkstemp(&tmp_file, "pack/tmp_bitmap_XXXXXX");
1017
1018         if (writer->pseudo_merges_nr)
1019                 options |= BITMAP_OPT_PSEUDO_MERGES;
1020
1021         f = hashfd(fd, tmp_file.buf);
1022
1023         memcpy(header.magic, BITMAP_IDX_SIGNATURE, sizeof(BITMAP_IDX_SIGNATURE));
1024         header.version = htons(default_version);
1025         header.options = htons(flags | options);
1026         header.entry_count = htonl(bitmap_writer_nr_selected_commits(writer));
1027         hashcpy(header.checksum, writer->pack_checksum, the_repository->hash_algo);
1028
1029         hashwrite(f, &header, sizeof(header) - GIT_MAX_RAWSZ + the_hash_algo->rawsz);
1030         dump_bitmap(f, writer->commits);
1031         dump_bitmap(f, writer->trees);
1032         dump_bitmap(f, writer->blobs);
1033         dump_bitmap(f, writer->tags);
1034
1035         if (options & BITMAP_OPT_LOOKUP_TABLE)
1036                 CALLOC_ARRAY(offsets, writer->to_pack->nr_objects);
1037
1038         for (i = 0; i < bitmap_writer_nr_selected_commits(writer); i++) {
1039                 struct bitmapped_commit *stored = &writer->selected[i];
1040                 int commit_pos = oid_pos(&stored->commit->object.oid, index,
1041                                          writer->to_pack->nr_objects,
1042                                          oid_access);
1043
1044                 if (commit_pos < 0)
1045                         BUG(_("trying to write commit not in index"));
1046                 stored->commit_pos = commit_pos;
1047         }
1048
1049         write_selected_commits_v1(writer, f, offsets);
1050
1051         if (options & BITMAP_OPT_PSEUDO_MERGES)
1052                 write_pseudo_merges(writer, f);
1053
1054         if (options & BITMAP_OPT_LOOKUP_TABLE)
1055                 write_lookup_table(writer, f, offsets);
1056
1057         if (options & BITMAP_OPT_HASH_CACHE)
1058                 write_hash_cache(f, index, writer->to_pack->nr_objects);
1059
1060         finalize_hashfile(f, NULL, FSYNC_COMPONENT_PACK_METADATA,
1061                           CSUM_HASH_IN_STREAM | CSUM_FSYNC | CSUM_CLOSE);
1062
1063         if (adjust_shared_perm(tmp_file.buf))
1064                 die_errno("unable to make temporary bitmap file readable");
1065
1066         if (rename(tmp_file.buf, filename))
1067                 die_errno("unable to rename temporary bitmap file to '%s'", filename);
1068
1069         strbuf_release(&tmp_file);
1070         free(offsets);
1071 }