pack-bitmap-write.c

   1 #define DISABLE_SIGN_COMPARE_WARNINGS
   2
   3 #include "git-compat-util.h"
   4 #include "environment.h"
   5 #include "gettext.h"
   6 #include "hex.h"
   7 #include "odb.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 #include "midx.h"
  29 #include "pack-revindex.h"
  30
  31 struct bitmapped_commit {
  32         struct commit *commit;
  33         struct ewah_bitmap *bitmap;
  34         struct ewah_bitmap *write_as;
  35         int flags;
  36         int xor_offset;
  37         uint32_t commit_pos;
  38         unsigned pseudo_merge : 1;
  39 };
  40
  41 static inline int bitmap_writer_nr_selected_commits(struct bitmap_writer *writer)
  42 {
  43         return writer->selected_nr - writer->pseudo_merges_nr;
  44 }
  45
  46 void bitmap_writer_init(struct bitmap_writer *writer, struct repository *r,
  47                         struct packing_data *pdata,
  48                         struct multi_pack_index *midx)
  49 {
  50         memset(writer, 0, sizeof(struct bitmap_writer));
  51         if (writer->bitmaps)
  52                 BUG("bitmap writer already initialized");
  53         writer->repo = r;
  54         writer->bitmaps = kh_init_oid_map();
  55         writer->pseudo_merge_commits = kh_init_oid_map();
  56         writer->to_pack = pdata;
  57         writer->midx = midx;
  58
  59         string_list_init_dup(&writer->pseudo_merge_groups);
  60
  61         load_pseudo_merges_from_config(r, &writer->pseudo_merge_groups);
  62 }
  63
  64 static void free_pseudo_merge_commit_idx(struct pseudo_merge_commit_idx *idx)
  65 {
  66         if (!idx)
  67                 return;
  68         free(idx->pseudo_merge);
  69         free(idx);
  70 }
  71
  72 static void pseudo_merge_group_release_cb(void *payload, const char *name UNUSED)
  73 {
  74         pseudo_merge_group_release(payload);
  75         free(payload);
  76 }
  77
  78 void bitmap_writer_free(struct bitmap_writer *writer)
  79 {
  80         uint32_t i;
  81         struct pseudo_merge_commit_idx *idx;
  82
  83         if (!writer)
  84                 return;
  85
  86         ewah_free(writer->commits);
  87         ewah_free(writer->trees);
  88         ewah_free(writer->blobs);
  89         ewah_free(writer->tags);
  90
  91         kh_destroy_oid_map(writer->bitmaps);
  92
  93         kh_foreach_value(writer->pseudo_merge_commits, idx,
  94                          free_pseudo_merge_commit_idx(idx));
  95         kh_destroy_oid_map(writer->pseudo_merge_commits);
  96         string_list_clear_func(&writer->pseudo_merge_groups,
  97                                pseudo_merge_group_release_cb);
  98
  99         for (i = 0; i < writer->selected_nr; i++) {
 100                 struct bitmapped_commit *bc = &writer->selected[i];
 101                 if (bc->write_as != bc->bitmap)
 102                         ewah_free(bc->write_as);
 103                 ewah_free(bc->bitmap);
 104         }
 105         free(writer->selected);
 106 }
 107
 108 void bitmap_writer_show_progress(struct bitmap_writer *writer, int show)
 109 {
 110         writer->show_progress = show;
 111 }
 112
 113 /**
 114  * Build the initial type index for the packfile or multi-pack-index
 115  */
 116 void bitmap_writer_build_type_index(struct bitmap_writer *writer,
 117                                     struct pack_idx_entry **index)
 118 {
 119         uint32_t i;
 120         uint32_t base_objects = 0;
 121
 122         if (writer->midx)
 123                 base_objects = writer->midx->num_objects +
 124                         writer->midx->num_objects_in_base;
 125
 126         writer->commits = ewah_new();
 127         writer->trees = ewah_new();
 128         writer->blobs = ewah_new();
 129         writer->tags = ewah_new();
 130         ALLOC_ARRAY(writer->to_pack->in_pack_pos, writer->to_pack->nr_objects);
 131
 132         for (i = 0; i < writer->to_pack->nr_objects; ++i) {
 133                 struct object_entry *entry = (struct object_entry *)index[i];
 134                 enum object_type real_type;
 135
 136                 oe_set_in_pack_pos(writer->to_pack, entry, i);
 137
 138                 switch (oe_type(entry)) {
 139                 case OBJ_COMMIT:
 140                 case OBJ_TREE:
 141                 case OBJ_BLOB:
 142                 case OBJ_TAG:
 143                         real_type = oe_type(entry);
 144                         break;
 145
 146                 default:
 147                         real_type = odb_read_object_info(writer->to_pack->repo->objects,
 148                                                          &entry->idx.oid, NULL);
 149                         break;
 150                 }
 151
 152                 switch (real_type) {
 153                 case OBJ_COMMIT:
 154                         ewah_set(writer->commits, i + base_objects);
 155                         break;
 156
 157                 case OBJ_TREE:
 158                         ewah_set(writer->trees, i + base_objects);
 159                         break;
 160
 161                 case OBJ_BLOB:
 162                         ewah_set(writer->blobs, i + base_objects);
 163                         break;
 164
 165                 case OBJ_TAG:
 166                         ewah_set(writer->tags, i + base_objects);
 167                         break;
 168
 169                 default:
 170                         die("Missing type information for %s (%d/%d)",
 171                             oid_to_hex(&entry->idx.oid), real_type,
 172                             oe_type(entry));
 173                 }
 174         }
 175 }
 176
 177 int bitmap_writer_has_bitmapped_object_id(struct bitmap_writer *writer,
 178                                           const struct object_id *oid)
 179 {
 180         return kh_get_oid_map(writer->bitmaps, *oid) != kh_end(writer->bitmaps);
 181 }
 182
 183 /**
 184  * Compute the actual bitmaps
 185  */
 186
 187 void bitmap_writer_push_commit(struct bitmap_writer *writer,
 188                                struct commit *commit, unsigned pseudo_merge)
 189 {
 190         if (writer->selected_nr >= writer->selected_alloc) {
 191                 writer->selected_alloc = (writer->selected_alloc + 32) * 2;
 192                 REALLOC_ARRAY(writer->selected, writer->selected_alloc);
 193         }
 194
 195         if (!pseudo_merge) {
 196                 int hash_ret;
 197                 khiter_t hash_pos = kh_put_oid_map(writer->bitmaps,
 198                                                    commit->object.oid,
 199                                                    &hash_ret);
 200
 201                 if (!hash_ret)
 202                         die(_("duplicate entry when writing bitmap index: %s"),
 203                             oid_to_hex(&commit->object.oid));
 204                 kh_value(writer->bitmaps, hash_pos) = NULL;
 205         }
 206
 207         writer->selected[writer->selected_nr].commit = commit;
 208         writer->selected[writer->selected_nr].bitmap = NULL;
 209         writer->selected[writer->selected_nr].write_as = NULL;
 210         writer->selected[writer->selected_nr].flags = 0;
 211         writer->selected[writer->selected_nr].pseudo_merge = pseudo_merge;
 212
 213         writer->selected_nr++;
 214 }
 215
 216 static uint32_t find_object_pos(struct bitmap_writer *writer,
 217                                 const struct object_id *oid, int *found)
 218 {
 219         struct object_entry *entry;
 220
 221         entry = packlist_find(writer->to_pack, oid);
 222         if (entry) {
 223                 uint32_t base_objects = 0;
 224                 if (writer->midx)
 225                         base_objects = writer->midx->num_objects +
 226                                 writer->midx->num_objects_in_base;
 227
 228                 if (found)
 229                         *found = 1;
 230                 return oe_in_pack_pos(writer->to_pack, entry) + base_objects;
 231         } else if (writer->midx) {
 232                 uint32_t at, pos;
 233
 234                 if (!bsearch_midx(oid, writer->midx, &at))
 235                         goto missing;
 236                 if (midx_to_pack_pos(writer->midx, at, &pos) < 0)
 237                         goto missing;
 238
 239                 if (found)
 240                         *found = 1;
 241                 return pos;
 242         }
 243
 244 missing:
 245         if (found)
 246                 *found = 0;
 247         warning("Failed to write bitmap index. Packfile doesn't have full closure "
 248                 "(object %s is missing)", oid_to_hex(oid));
 249         return 0;
 250 }
 251
 252 static void compute_xor_offsets(struct bitmap_writer *writer)
 253 {
 254         static const int MAX_XOR_OFFSET_SEARCH = 10;
 255
 256         int i, next = 0;
 257
 258         while (next < writer->selected_nr) {
 259                 struct bitmapped_commit *stored = &writer->selected[next];
 260                 int best_offset = 0;
 261                 struct ewah_bitmap *best_bitmap = stored->bitmap;
 262                 struct ewah_bitmap *test_xor;
 263
 264                 if (stored->pseudo_merge)
 265                         goto next;
 266
 267                 for (i = 1; i <= MAX_XOR_OFFSET_SEARCH; ++i) {
 268                         int curr = next - i;
 269
 270                         if (curr < 0)
 271                                 break;
 272                         if (writer->selected[curr].pseudo_merge)
 273                                 continue;
 274
 275                         test_xor = ewah_pool_new();
 276                         ewah_xor(writer->selected[curr].bitmap, stored->bitmap, test_xor);
 277
 278                         if (test_xor->buffer_size < best_bitmap->buffer_size) {
 279                                 if (best_bitmap != stored->bitmap)
 280                                         ewah_pool_free(best_bitmap);
 281
 282                                 best_bitmap = test_xor;
 283                                 best_offset = i;
 284                         } else {
 285                                 ewah_pool_free(test_xor);
 286                         }
 287                 }
 288
 289 next:
 290                 stored->xor_offset = best_offset;
 291                 stored->write_as = best_bitmap;
 292
 293                 next++;
 294         }
 295 }
 296
 297 struct bb_commit {
 298         struct commit_list *reverse_edges;
 299         struct bitmap *commit_mask;
 300         struct bitmap *bitmap;
 301         unsigned selected:1,
 302                  maximal:1,
 303                  pseudo_merge:1;
 304         unsigned idx; /* within selected array */
 305 };
 306
 307 static void clear_bb_commit(struct bb_commit *commit)
 308 {
 309         free_commit_list(commit->reverse_edges);
 310         bitmap_free(commit->commit_mask);
 311         bitmap_free(commit->bitmap);
 312 }
 313
 314 define_commit_slab(bb_data, struct bb_commit);
 315
 316 struct bitmap_builder {
 317         struct bb_data data;
 318         struct commit **commits;
 319         size_t commits_nr, commits_alloc;
 320 };
 321
 322 static void bitmap_builder_init(struct bitmap_builder *bb,
 323                                 struct bitmap_writer *writer,
 324                                 struct bitmap_index *old_bitmap)
 325 {
 326         struct rev_info revs;
 327         struct commit *commit;
 328         struct commit_list *reusable = NULL;
 329         struct commit_list *r;
 330         unsigned int i, num_maximal = 0;
 331
 332         memset(bb, 0, sizeof(*bb));
 333         init_bb_data(&bb->data);
 334
 335         reset_revision_walk();
 336         repo_init_revisions(writer->to_pack->repo, &revs, NULL);
 337         revs.topo_order = 1;
 338         revs.first_parent_only = 1;
 339
 340         for (i = 0; i < writer->selected_nr; i++) {
 341                 struct bitmapped_commit *bc = &writer->selected[i];
 342                 struct bb_commit *ent = bb_data_at(&bb->data, bc->commit);
 343
 344                 ent->selected = 1;
 345                 ent->maximal = 1;
 346                 ent->pseudo_merge = bc->pseudo_merge;
 347                 ent->idx = i;
 348
 349                 ent->commit_mask = bitmap_new();
 350                 bitmap_set(ent->commit_mask, i);
 351
 352                 add_pending_object(&revs, &bc->commit->object, "");
 353         }
 354
 355         if (prepare_revision_walk(&revs))
 356                 die("revision walk setup failed");
 357
 358         while ((commit = get_revision(&revs))) {
 359                 struct commit_list *p = commit->parents;
 360                 struct bb_commit *c_ent;
 361
 362                 parse_commit_or_die(commit);
 363
 364                 c_ent = bb_data_at(&bb->data, commit);
 365
 366                 /*
 367                  * If there is no commit_mask, there is no reason to iterate
 368                  * over this commit; it is not selected (if it were, it would
 369                  * not have a blank commit mask) and all its children have
 370                  * existing bitmaps (see the comment starting with "This commit
 371                  * has an existing bitmap" below), so it does not contribute
 372                  * anything to the final bitmap file or its descendants.
 373                  */
 374                 if (!c_ent->commit_mask)
 375                         continue;
 376
 377                 if (old_bitmap && bitmap_for_commit(old_bitmap, commit)) {
 378                         /*
 379                          * This commit has an existing bitmap, so we can
 380                          * get its bits immediately without an object
 381                          * walk. That is, it is reusable as-is and there is no
 382                          * need to continue walking beyond it.
 383                          *
 384                          * Mark it as such and add it to bb->commits separately
 385                          * to avoid allocating a position in the commit mask.
 386                          */
 387                         commit_list_insert(commit, &reusable);
 388                         goto next;
 389                 }
 390
 391                 if (c_ent->maximal) {
 392                         num_maximal++;
 393                         ALLOC_GROW(bb->commits, bb->commits_nr + 1, bb->commits_alloc);
 394                         bb->commits[bb->commits_nr++] = commit;
 395                 }
 396
 397                 if (p) {
 398                         struct bb_commit *p_ent = bb_data_at(&bb->data, p->item);
 399                         int c_not_p, p_not_c;
 400
 401                         if (!p_ent->commit_mask) {
 402                                 p_ent->commit_mask = bitmap_new();
 403                                 c_not_p = 1;
 404                                 p_not_c = 0;
 405                         } else {
 406                                 c_not_p = bitmap_is_subset(c_ent->commit_mask, p_ent->commit_mask);
 407                                 p_not_c = bitmap_is_subset(p_ent->commit_mask, c_ent->commit_mask);
 408                         }
 409
 410                         if (!c_not_p)
 411                                 continue;
 412
 413                         bitmap_or(p_ent->commit_mask, c_ent->commit_mask);
 414
 415                         if (p_not_c)
 416                                 p_ent->maximal = 1;
 417                         else {
 418                                 p_ent->maximal = 0;
 419                                 free_commit_list(p_ent->reverse_edges);
 420                                 p_ent->reverse_edges = NULL;
 421                         }
 422
 423                         if (c_ent->maximal) {
 424                                 commit_list_insert(commit, &p_ent->reverse_edges);
 425                         } else {
 426                                 struct commit_list *cc = c_ent->reverse_edges;
 427
 428                                 for (; cc; cc = cc->next) {
 429                                         if (!commit_list_contains(cc->item, p_ent->reverse_edges))
 430                                                 commit_list_insert(cc->item, &p_ent->reverse_edges);
 431                                 }
 432                         }
 433                 }
 434
 435 next:
 436                 bitmap_free(c_ent->commit_mask);
 437                 c_ent->commit_mask = NULL;
 438         }
 439
 440         for (r = reusable; r; r = r->next) {
 441                 ALLOC_GROW(bb->commits, bb->commits_nr + 1, bb->commits_alloc);
 442                 bb->commits[bb->commits_nr++] = r->item;
 443         }
 444
 445         trace2_data_intmax("pack-bitmap-write", writer->repo,
 446                            "num_selected_commits", writer->selected_nr);
 447         trace2_data_intmax("pack-bitmap-write", writer->repo,
 448                            "num_maximal_commits", num_maximal);
 449
 450         release_revisions(&revs);
 451         free_commit_list(reusable);
 452 }
 453
 454 static void bitmap_builder_clear(struct bitmap_builder *bb)
 455 {
 456         deep_clear_bb_data(&bb->data, clear_bb_commit);
 457         free(bb->commits);
 458         bb->commits_nr = bb->commits_alloc = 0;
 459 }
 460
 461 static int fill_bitmap_tree(struct bitmap_writer *writer,
 462                             struct bitmap *bitmap,
 463                             struct tree *tree)
 464 {
 465         int found;
 466         uint32_t pos;
 467         struct tree_desc desc;
 468         struct name_entry entry;
 469
 470         /*
 471          * If our bit is already set, then there is nothing to do. Both this
 472          * tree and all of its children will be set.
 473          */
 474         pos = find_object_pos(writer, &tree->object.oid, &found);
 475         if (!found)
 476                 return -1;
 477         if (bitmap_get(bitmap, pos))
 478                 return 0;
 479         bitmap_set(bitmap, pos);
 480
 481         if (parse_tree(tree) < 0)
 482                 die("unable to load tree object %s",
 483                     oid_to_hex(&tree->object.oid));
 484         init_tree_desc(&desc, &tree->object.oid, tree->buffer, tree->size);
 485
 486         while (tree_entry(&desc, &entry)) {
 487                 switch (object_type(entry.mode)) {
 488                 case OBJ_TREE:
 489                         if (fill_bitmap_tree(writer, bitmap,
 490                                              lookup_tree(writer->repo, &entry.oid)) < 0)
 491                                 return -1;
 492                         break;
 493                 case OBJ_BLOB:
 494                         pos = find_object_pos(writer, &entry.oid, &found);
 495                         if (!found)
 496                                 return -1;
 497                         bitmap_set(bitmap, pos);
 498                         break;
 499                 default:
 500                         /* Gitlink, etc; not reachable */
 501                         break;
 502                 }
 503         }
 504
 505         free_tree_buffer(tree);
 506         return 0;
 507 }
 508
 509 static int reused_bitmaps_nr;
 510 static int reused_pseudo_merge_bitmaps_nr;
 511
 512 static int fill_bitmap_commit(struct bitmap_writer *writer,
 513                               struct bb_commit *ent,
 514                               struct commit *commit,
 515                               struct prio_queue *queue,
 516                               struct prio_queue *tree_queue,
 517                               struct bitmap_index *old_bitmap,
 518                               const uint32_t *mapping)
 519 {
 520         int found;
 521         uint32_t pos;
 522         if (!ent->bitmap)
 523                 ent->bitmap = bitmap_new();
 524
 525         prio_queue_put(queue, commit);
 526
 527         while (queue->nr) {
 528                 struct commit_list *p;
 529                 struct commit *c = prio_queue_get(queue);
 530
 531                 if (old_bitmap && mapping) {
 532                         struct ewah_bitmap *old;
 533                         struct bitmap *remapped = bitmap_new();
 534
 535                         if (commit->object.flags & BITMAP_PSEUDO_MERGE)
 536                                 old = pseudo_merge_bitmap_for_commit(old_bitmap, c);
 537                         else
 538                                 old = bitmap_for_commit(old_bitmap, c);
 539                         /*
 540                          * If this commit has an old bitmap, then translate that
 541                          * bitmap and add its bits to this one. No need to walk
 542                          * parents or the tree for this commit.
 543                          */
 544                         if (old && !rebuild_bitmap(mapping, old, remapped)) {
 545                                 bitmap_or(ent->bitmap, remapped);
 546                                 bitmap_free(remapped);
 547                                 if (commit->object.flags & BITMAP_PSEUDO_MERGE)
 548                                         reused_pseudo_merge_bitmaps_nr++;
 549                                 else
 550                                         reused_bitmaps_nr++;
 551                                 continue;
 552                         }
 553                         bitmap_free(remapped);
 554                 }
 555
 556                 /*
 557                  * Mark ourselves and queue our tree. The commit
 558                  * walk ensures we cover all parents.
 559                  */
 560                 if (!(c->object.flags & BITMAP_PSEUDO_MERGE)) {
 561                         pos = find_object_pos(writer, &c->object.oid, &found);
 562                         if (!found)
 563                                 return -1;
 564                         bitmap_set(ent->bitmap, pos);
 565                         prio_queue_put(tree_queue,
 566                                        repo_get_commit_tree(writer->repo, c));
 567                 }
 568
 569                 for (p = c->parents; p; p = p->next) {
 570                         pos = find_object_pos(writer, &p->item->object.oid,
 571                                               &found);
 572                         if (!found)
 573                                 return -1;
 574                         if (!bitmap_get(ent->bitmap, pos)) {
 575                                 bitmap_set(ent->bitmap, pos);
 576                                 prio_queue_put(queue, p->item);
 577                         }
 578                 }
 579         }
 580
 581         while (tree_queue->nr) {
 582                 if (fill_bitmap_tree(writer, ent->bitmap,
 583                                      prio_queue_get(tree_queue)) < 0)
 584                         return -1;
 585         }
 586         return 0;
 587 }
 588
 589 static void store_selected(struct bitmap_writer *writer,
 590                            struct bb_commit *ent, struct commit *commit)
 591 {
 592         struct bitmapped_commit *stored = &writer->selected[ent->idx];
 593         khiter_t hash_pos;
 594
 595         stored->bitmap = bitmap_to_ewah(ent->bitmap);
 596
 597         if (ent->pseudo_merge)
 598                 return;
 599
 600         hash_pos = kh_get_oid_map(writer->bitmaps, commit->object.oid);
 601         if (hash_pos == kh_end(writer->bitmaps))
 602                 die(_("attempted to store non-selected commit: '%s'"),
 603                     oid_to_hex(&commit->object.oid));
 604
 605         kh_value(writer->bitmaps, hash_pos) = stored;
 606 }
 607
 608 int bitmap_writer_build(struct bitmap_writer *writer)
 609 {
 610         struct bitmap_builder bb;
 611         size_t i;
 612         int nr_stored = 0; /* for progress */
 613         struct prio_queue queue = { compare_commits_by_gen_then_commit_date };
 614         struct prio_queue tree_queue = { NULL };
 615         struct bitmap_index *old_bitmap;
 616         uint32_t *mapping = NULL;
 617         int closed = 1; /* until proven otherwise */
 618
 619         if (writer->show_progress)
 620                 writer->progress = start_progress(writer->repo,
 621                                                   "Building bitmaps",
 622                                                   writer->selected_nr);
 623         trace2_region_enter("pack-bitmap-write", "building_bitmaps_total",
 624                             writer->repo);
 625
 626         old_bitmap = prepare_bitmap_git(writer->to_pack->repo);
 627         if (old_bitmap)
 628                 mapping = create_bitmap_mapping(old_bitmap, writer->to_pack);
 629         else
 630                 mapping = NULL;
 631
 632         bitmap_builder_init(&bb, writer, old_bitmap);
 633         for (i = bb.commits_nr; i > 0; i--) {
 634                 struct commit *commit = bb.commits[i-1];
 635                 struct bb_commit *ent = bb_data_at(&bb.data, commit);
 636                 struct commit *child;
 637                 int reused = 0;
 638
 639                 if (fill_bitmap_commit(writer, ent, commit, &queue, &tree_queue,
 640                                        old_bitmap, mapping) < 0) {
 641                         closed = 0;
 642                         break;
 643                 }
 644
 645                 if (ent->selected) {
 646                         store_selected(writer, ent, commit);
 647                         nr_stored++;
 648                         display_progress(writer->progress, nr_stored);
 649                 }
 650
 651                 while ((child = pop_commit(&ent->reverse_edges))) {
 652                         struct bb_commit *child_ent =
 653                                 bb_data_at(&bb.data, child);
 654
 655                         if (child_ent->bitmap)
 656                                 bitmap_or(child_ent->bitmap, ent->bitmap);
 657                         else if (reused)
 658                                 child_ent->bitmap = bitmap_dup(ent->bitmap);
 659                         else {
 660                                 child_ent->bitmap = ent->bitmap;
 661                                 reused = 1;
 662                         }
 663                 }
 664                 if (!reused)
 665                         bitmap_free(ent->bitmap);
 666                 ent->bitmap = NULL;
 667         }
 668         clear_prio_queue(&queue);
 669         clear_prio_queue(&tree_queue);
 670         bitmap_builder_clear(&bb);
 671         free_bitmap_index(old_bitmap);
 672         free(mapping);
 673
 674         trace2_region_leave("pack-bitmap-write", "building_bitmaps_total",
 675                             writer->repo);
 676         trace2_data_intmax("pack-bitmap-write", writer->repo,
 677                            "building_bitmaps_reused", reused_bitmaps_nr);
 678         trace2_data_intmax("pack-bitmap-write", writer->repo,
 679                            "building_bitmaps_pseudo_merge_reused",
 680                            reused_pseudo_merge_bitmaps_nr);
 681
 682         stop_progress(&writer->progress);
 683
 684         if (closed)
 685                 compute_xor_offsets(writer);
 686         return closed ? 0 : -1;
 687 }
 688
 689 /**
 690  * Select the commits that will be bitmapped
 691  */
 692 static inline unsigned int next_commit_index(unsigned int idx)
 693 {
 694         static const unsigned int MIN_COMMITS = 100;
 695         static const unsigned int MAX_COMMITS = 5000;
 696
 697         static const unsigned int MUST_REGION = 100;
 698         static const unsigned int MIN_REGION = 20000;
 699
 700         unsigned int offset, next;
 701
 702         if (idx <= MUST_REGION)
 703                 return 0;
 704
 705         if (idx <= MIN_REGION) {
 706                 offset = idx - MUST_REGION;
 707                 return (offset < MIN_COMMITS) ? offset : MIN_COMMITS;
 708         }
 709
 710         offset = idx - MIN_REGION;
 711         next = (offset < MAX_COMMITS) ? offset : MAX_COMMITS;
 712
 713         return (next > MIN_COMMITS) ? next : MIN_COMMITS;
 714 }
 715
 716 static int date_compare(const void *_a, const void *_b)
 717 {
 718         struct commit *a = *(struct commit **)_a;
 719         struct commit *b = *(struct commit **)_b;
 720         return (long)b->date - (long)a->date;
 721 }
 722
 723 void bitmap_writer_select_commits(struct bitmap_writer *writer,
 724                                   struct commit **indexed_commits,
 725                                   unsigned int indexed_commits_nr)
 726 {
 727         unsigned int i = 0, j, next;
 728
 729         QSORT(indexed_commits, indexed_commits_nr, date_compare);
 730
 731         if (indexed_commits_nr < 100) {
 732                 for (i = 0; i < indexed_commits_nr; ++i)
 733                         bitmap_writer_push_commit(writer, indexed_commits[i], 0);
 734
 735                 select_pseudo_merges(writer);
 736
 737                 return;
 738         }
 739
 740         if (writer->show_progress)
 741                 writer->progress = start_progress(writer->repo,
 742                                                   "Selecting bitmap commits", 0);
 743
 744         for (;;) {
 745                 struct commit *chosen = NULL;
 746
 747                 next = next_commit_index(i);
 748
 749                 if (i + next >= indexed_commits_nr)
 750                         break;
 751
 752                 if (next == 0) {
 753                         chosen = indexed_commits[i];
 754                 } else {
 755                         chosen = indexed_commits[i + next];
 756
 757                         for (j = 0; j <= next; ++j) {
 758                                 struct commit *cm = indexed_commits[i + j];
 759
 760                                 if ((cm->object.flags & NEEDS_BITMAP) != 0) {
 761                                         chosen = cm;
 762                                         break;
 763                                 }
 764
 765                                 if (cm->parents && cm->parents->next)
 766                                         chosen = cm;
 767                         }
 768                 }
 769
 770                 bitmap_writer_push_commit(writer, chosen, 0);
 771
 772                 i += next + 1;
 773                 display_progress(writer->progress, i);
 774         }
 775
 776         stop_progress(&writer->progress);
 777
 778         select_pseudo_merges(writer);
 779 }
 780
 781
 782 static int hashwrite_ewah_helper(void *f, const void *buf, size_t len)
 783 {
 784         /* hashwrite will die on error */
 785         hashwrite(f, buf, len);
 786         return len;
 787 }
 788
 789 /**
 790  * Write the bitmap index to disk
 791  */
 792 static inline void dump_bitmap(struct hashfile *f, struct ewah_bitmap *bitmap)
 793 {
 794         if (ewah_serialize_to(bitmap, hashwrite_ewah_helper, f) < 0)
 795                 die("Failed to write bitmap index");
 796 }
 797
 798 static const struct object_id *oid_access(size_t pos, const void *table)
 799 {
 800         const struct pack_idx_entry * const *index = table;
 801         return &index[pos]->oid;
 802 }
 803
 804 static void write_selected_commits_v1(struct bitmap_writer *writer,
 805                                       struct hashfile *f, off_t *offsets)
 806 {
 807         int i;
 808
 809         for (i = 0; i < bitmap_writer_nr_selected_commits(writer); ++i) {
 810                 struct bitmapped_commit *stored = &writer->selected[i];
 811                 if (stored->pseudo_merge)
 812                         BUG("unexpected pseudo-merge among selected: %s",
 813                             oid_to_hex(&stored->commit->object.oid));
 814
 815                 if (offsets)
 816                         offsets[i] = hashfile_total(f);
 817
 818                 hashwrite_be32(f, stored->commit_pos);
 819                 hashwrite_u8(f, stored->xor_offset);
 820                 hashwrite_u8(f, stored->flags);
 821
 822                 dump_bitmap(f, stored->write_as);
 823         }
 824 }
 825
 826 static void write_pseudo_merges(struct bitmap_writer *writer,
 827                                 struct hashfile *f)
 828 {
 829         struct oid_array commits = OID_ARRAY_INIT;
 830         struct bitmap **commits_bitmap = NULL;
 831         off_t *pseudo_merge_ofs = NULL;
 832         off_t start, table_start, next_ext;
 833
 834         uint32_t base = bitmap_writer_nr_selected_commits(writer);
 835         size_t i, j = 0;
 836
 837         CALLOC_ARRAY(commits_bitmap, writer->pseudo_merges_nr);
 838         CALLOC_ARRAY(pseudo_merge_ofs, writer->pseudo_merges_nr);
 839
 840         for (i = 0; i < writer->pseudo_merges_nr; i++) {
 841                 struct bitmapped_commit *merge = &writer->selected[base + i];
 842                 struct commit_list *p;
 843
 844                 if (!merge->pseudo_merge)
 845                         BUG("found non-pseudo merge commit at %"PRIuMAX, (uintmax_t)i);
 846
 847                 commits_bitmap[i] = bitmap_new();
 848
 849                 for (p = merge->commit->parents; p; p = p->next)
 850                         bitmap_set(commits_bitmap[i],
 851                                    find_object_pos(writer, &p->item->object.oid,
 852                                                    NULL));
 853         }
 854
 855         start = hashfile_total(f);
 856
 857         for (i = 0; i < writer->pseudo_merges_nr; i++) {
 858                 struct ewah_bitmap *commits_ewah = bitmap_to_ewah(commits_bitmap[i]);
 859
 860                 pseudo_merge_ofs[i] = hashfile_total(f);
 861
 862                 dump_bitmap(f, commits_ewah);
 863                 dump_bitmap(f, writer->selected[base+i].write_as);
 864
 865                 ewah_free(commits_ewah);
 866         }
 867
 868         next_ext = st_add(hashfile_total(f),
 869                           st_mult(kh_size(writer->pseudo_merge_commits),
 870                                   sizeof(uint64_t)));
 871
 872         table_start = hashfile_total(f);
 873
 874         commits.alloc = kh_size(writer->pseudo_merge_commits);
 875         CALLOC_ARRAY(commits.oid, commits.alloc);
 876
 877         for (i = kh_begin(writer->pseudo_merge_commits); i != kh_end(writer->pseudo_merge_commits); i++) {
 878                 if (!kh_exist(writer->pseudo_merge_commits, i))
 879                         continue;
 880                 oid_array_append(&commits, &kh_key(writer->pseudo_merge_commits, i));
 881         }
 882
 883         oid_array_sort(&commits);
 884
 885         /* write lookup table (non-extended) */
 886         for (i = 0; i < commits.nr; i++) {
 887                 int hash_pos;
 888                 struct pseudo_merge_commit_idx *c;
 889
 890                 hash_pos = kh_get_oid_map(writer->pseudo_merge_commits,
 891                                           commits.oid[i]);
 892                 if (hash_pos == kh_end(writer->pseudo_merge_commits))
 893                         BUG("could not find pseudo-merge commit %s",
 894                             oid_to_hex(&commits.oid[i]));
 895
 896                 c = kh_value(writer->pseudo_merge_commits, hash_pos);
 897
 898                 hashwrite_be32(f, find_object_pos(writer, &commits.oid[i],
 899                                                   NULL));
 900                 if (c->nr == 1)
 901                         hashwrite_be64(f, pseudo_merge_ofs[c->pseudo_merge[0]]);
 902                 else if (c->nr > 1) {
 903                         if (next_ext & ((uint64_t)1<<63))
 904                                 die(_("too many pseudo-merges"));
 905                         hashwrite_be64(f, next_ext | ((uint64_t)1<<63));
 906                         next_ext = st_add3(next_ext,
 907                                            sizeof(uint32_t),
 908                                            st_mult(c->nr, sizeof(uint64_t)));
 909                 } else
 910                         BUG("expected commit '%s' to have at least one "
 911                             "pseudo-merge", oid_to_hex(&commits.oid[i]));
 912         }
 913
 914         /* write lookup table (extended) */
 915         for (i = 0; i < commits.nr; i++) {
 916                 int hash_pos;
 917                 struct pseudo_merge_commit_idx *c;
 918
 919                 hash_pos = kh_get_oid_map(writer->pseudo_merge_commits,
 920                                           commits.oid[i]);
 921                 if (hash_pos == kh_end(writer->pseudo_merge_commits))
 922                         BUG("could not find pseudo-merge commit %s",
 923                             oid_to_hex(&commits.oid[i]));
 924
 925                 c = kh_value(writer->pseudo_merge_commits, hash_pos);
 926                 if (c->nr == 1)
 927                         continue;
 928
 929                 hashwrite_be32(f, c->nr);
 930                 for (j = 0; j < c->nr; j++)
 931                         hashwrite_be64(f, pseudo_merge_ofs[c->pseudo_merge[j]]);
 932         }
 933
 934         /* write positions for all pseudo merges */
 935         for (i = 0; i < writer->pseudo_merges_nr; i++)
 936                 hashwrite_be64(f, pseudo_merge_ofs[i]);
 937
 938         hashwrite_be32(f, writer->pseudo_merges_nr);
 939         hashwrite_be32(f, kh_size(writer->pseudo_merge_commits));
 940         hashwrite_be64(f, table_start - start);
 941         hashwrite_be64(f, hashfile_total(f) - start + sizeof(uint64_t));
 942
 943         for (i = 0; i < writer->pseudo_merges_nr; i++)
 944                 bitmap_free(commits_bitmap[i]);
 945
 946         oid_array_clear(&commits);
 947         free(pseudo_merge_ofs);
 948         free(commits_bitmap);
 949 }
 950
 951 static int table_cmp(const void *_va, const void *_vb, void *_data)
 952 {
 953         struct bitmap_writer *writer = _data;
 954         struct bitmapped_commit *a = &writer->selected[*(uint32_t *)_va];
 955         struct bitmapped_commit *b = &writer->selected[*(uint32_t *)_vb];
 956
 957         if (a->commit_pos < b->commit_pos)
 958                 return -1;
 959         else if (a->commit_pos > b->commit_pos)
 960                 return 1;
 961
 962         return 0;
 963 }
 964
 965 static void write_lookup_table(struct bitmap_writer *writer, struct hashfile *f,
 966                                off_t *offsets)
 967 {
 968         uint32_t i;
 969         uint32_t *table, *table_inv;
 970
 971         ALLOC_ARRAY(table, bitmap_writer_nr_selected_commits(writer));
 972         ALLOC_ARRAY(table_inv, bitmap_writer_nr_selected_commits(writer));
 973
 974         for (i = 0; i < bitmap_writer_nr_selected_commits(writer); i++)
 975                 table[i] = i;
 976
 977         /*
 978          * At the end of this sort table[j] = i means that the i'th
 979          * bitmap corresponds to j'th bitmapped commit (among the selected
 980          * commits) in lex order of OIDs.
 981          */
 982         QSORT_S(table, bitmap_writer_nr_selected_commits(writer), table_cmp, writer);
 983
 984         /* table_inv helps us discover that relationship (i'th bitmap
 985          * to j'th commit by j = table_inv[i])
 986          */
 987         for (i = 0; i < bitmap_writer_nr_selected_commits(writer); i++)
 988                 table_inv[table[i]] = i;
 989
 990         trace2_region_enter("pack-bitmap-write", "writing_lookup_table", writer->repo);
 991         for (i = 0; i < bitmap_writer_nr_selected_commits(writer); i++) {
 992                 struct bitmapped_commit *selected = &writer->selected[table[i]];
 993                 uint32_t xor_offset = selected->xor_offset;
 994                 uint32_t xor_row;
 995
 996                 if (xor_offset) {
 997                         /*
 998                          * xor_index stores the index (in the bitmap entries)
 999                          * of the corresponding xor bitmap. But we need to convert
1000                          * this index into lookup table's index. So, table_inv[xor_index]
1001                          * gives us the index position w.r.t. the lookup table.
1002                          *
1003                          * If "k = table[i] - xor_offset" then the xor base is the k'th
1004                          * bitmap. `table_inv[k]` gives us the position of that bitmap
1005                          * in the lookup table.
1006                          */
1007                         uint32_t xor_index = table[i] - xor_offset;
1008                         xor_row = table_inv[xor_index];
1009                 } else {
1010                         xor_row = 0xffffffff;
1011                 }
1012
1013                 hashwrite_be32(f, writer->selected[table[i]].commit_pos);
1014                 hashwrite_be64(f, (uint64_t)offsets[table[i]]);
1015                 hashwrite_be32(f, xor_row);
1016         }
1017         trace2_region_leave("pack-bitmap-write", "writing_lookup_table", writer->repo);
1018
1019         free(table);
1020         free(table_inv);
1021 }
1022
1023 static void write_hash_cache(struct hashfile *f,
1024                              struct pack_idx_entry **index,
1025                              uint32_t index_nr)
1026 {
1027         uint32_t i;
1028
1029         for (i = 0; i < index_nr; ++i) {
1030                 struct object_entry *entry = (struct object_entry *)index[i];
1031                 hashwrite_be32(f, entry->hash);
1032         }
1033 }
1034
1035 void bitmap_writer_set_checksum(struct bitmap_writer *writer,
1036                                 const unsigned char *sha1)
1037 {
1038         hashcpy(writer->pack_checksum, sha1, writer->repo->hash_algo);
1039 }
1040
1041 void bitmap_writer_finish(struct bitmap_writer *writer,
1042                           struct pack_idx_entry **index,
1043                           const char *filename,
1044                           uint16_t options)
1045 {
1046         static uint16_t default_version = 1;
1047         static uint16_t flags = BITMAP_OPT_FULL_DAG;
1048         struct strbuf tmp_file = STRBUF_INIT;
1049         struct hashfile *f;
1050         off_t *offsets = NULL;
1051         uint32_t i, base_objects;
1052
1053         struct bitmap_disk_header header;
1054
1055         int fd = odb_mkstemp(writer->repo->objects, &tmp_file,
1056                              "pack/tmp_bitmap_XXXXXX");
1057
1058         if (writer->pseudo_merges_nr)
1059                 options |= BITMAP_OPT_PSEUDO_MERGES;
1060
1061         f = hashfd(writer->repo->hash_algo, fd, tmp_file.buf);
1062
1063         memcpy(header.magic, BITMAP_IDX_SIGNATURE, sizeof(BITMAP_IDX_SIGNATURE));
1064         header.version = htons(default_version);
1065         header.options = htons(flags | options);
1066         header.entry_count = htonl(bitmap_writer_nr_selected_commits(writer));
1067         hashcpy(header.checksum, writer->pack_checksum, writer->repo->hash_algo);
1068
1069         hashwrite(f, &header, sizeof(header) - GIT_MAX_RAWSZ + writer->repo->hash_algo->rawsz);
1070         dump_bitmap(f, writer->commits);
1071         dump_bitmap(f, writer->trees);
1072         dump_bitmap(f, writer->blobs);
1073         dump_bitmap(f, writer->tags);
1074
1075         if (options & BITMAP_OPT_LOOKUP_TABLE)
1076                 CALLOC_ARRAY(offsets, writer->to_pack->nr_objects);
1077
1078         if (writer->midx)
1079                 base_objects = writer->midx->num_objects +
1080                         writer->midx->num_objects_in_base;
1081         else
1082                 base_objects = 0;
1083
1084         for (i = 0; i < bitmap_writer_nr_selected_commits(writer); i++) {
1085                 struct bitmapped_commit *stored = &writer->selected[i];
1086                 int commit_pos = oid_pos(&stored->commit->object.oid, index,
1087                                          writer->to_pack->nr_objects,
1088                                          oid_access);
1089
1090                 if (commit_pos < 0)
1091                         BUG("trying to write commit not in index");
1092                 stored->commit_pos = commit_pos + base_objects;
1093         }
1094
1095         write_selected_commits_v1(writer, f, offsets);
1096
1097         if (options & BITMAP_OPT_PSEUDO_MERGES)
1098                 write_pseudo_merges(writer, f);
1099
1100         if (options & BITMAP_OPT_LOOKUP_TABLE)
1101                 write_lookup_table(writer, f, offsets);
1102
1103         if (options & BITMAP_OPT_HASH_CACHE)
1104                 write_hash_cache(f, index, writer->to_pack->nr_objects);
1105
1106         finalize_hashfile(f, NULL, FSYNC_COMPONENT_PACK_METADATA,
1107                           CSUM_HASH_IN_STREAM | CSUM_FSYNC | CSUM_CLOSE);
1108
1109         if (adjust_shared_perm(writer->repo, tmp_file.buf))
1110                 die_errno("unable to make temporary bitmap file readable");
1111
1112         if (rename(tmp_file.buf, filename))
1113                 die_errno("unable to rename temporary bitmap file to '%s'", filename);
1114
1115         strbuf_release(&tmp_file);
1116         free(offsets);
1117 }