git.oblomov.eu Git - git/blob - pack-bitmap.c

   1 #include "cache.h"
   2 #include "commit.h"
   3 #include "tag.h"
   4 #include "diff.h"
   5 #include "revision.h"
   6 #include "progress.h"
   7 #include "list-objects.h"
   8 #include "pack.h"
   9 #include "pack-bitmap.h"
  10 #include "pack-revindex.h"
  11 #include "pack-objects.h"
  12 #include "packfile.h"
  13 #include "repository.h"
  14 #include "object-store.h"
  15
  16 /*
  17  * An entry on the bitmap index, representing the bitmap for a given
  18  * commit.
  19  */
  20 struct stored_bitmap {
  21         struct object_id oid;
  22         struct ewah_bitmap *root;
  23         struct stored_bitmap *xor;
  24         int flags;
  25 };
  26
  27 /*
  28  * The active bitmap index for a repository. By design, repositories only have
  29  * a single bitmap index available (the index for the biggest packfile in
  30  * the repository), since bitmap indexes need full closure.
  31  *
  32  * If there is more than one bitmap index available (e.g. because of alternates),
  33  * the active bitmap index is the largest one.
  34  */
  35 struct bitmap_index {
  36         /* Packfile to which this bitmap index belongs to */
  37         struct packed_git *pack;
  38
  39         /*
  40          * Mark the first `reuse_objects` in the packfile as reused:
  41          * they will be sent as-is without using them for repacking
  42          * calculations
  43          */
  44         uint32_t reuse_objects;
  45
  46         /* mmapped buffer of the whole bitmap index */
  47         unsigned char *map;
  48         size_t map_size; /* size of the mmaped buffer */
  49         size_t map_pos; /* current position when loading the index */
  50
  51         /*
  52          * Type indexes.
  53          *
  54          * Each bitmap marks which objects in the packfile  are of the given
  55          * type. This provides type information when yielding the objects from
  56          * the packfile during a walk, which allows for better delta bases.
  57          */
  58         struct ewah_bitmap *commits;
  59         struct ewah_bitmap *trees;
  60         struct ewah_bitmap *blobs;
  61         struct ewah_bitmap *tags;
  62
  63         /* Map from object ID -> `stored_bitmap` for all the bitmapped commits */
  64         kh_oid_map_t *bitmaps;
  65
  66         /* Number of bitmapped commits */
  67         uint32_t entry_count;
  68
  69         /* If not NULL, this is a name-hash cache pointing into map. */
  70         uint32_t *hashes;
  71
  72         /*
  73          * Extended index.
  74          *
  75          * When trying to perform bitmap operations with objects that are not
  76          * packed in `pack`, these objects are added to this "fake index" and
  77          * are assumed to appear at the end of the packfile for all operations
  78          */
  79         struct eindex {
  80                 struct object **objects;
  81                 uint32_t *hashes;
  82                 uint32_t count, alloc;
  83                 kh_oid_pos_t *positions;
  84         } ext_index;
  85
  86         /* Bitmap result of the last performed walk */
  87         struct bitmap *result;
  88
  89         /* "have" bitmap from the last performed walk */
  90         struct bitmap *haves;
  91
  92         /* Version of the bitmap index */
  93         unsigned int version;
  94 };
  95
  96 static struct ewah_bitmap *lookup_stored_bitmap(struct stored_bitmap *st)
  97 {
  98         struct ewah_bitmap *parent;
  99         struct ewah_bitmap *composed;
 100
 101         if (st->xor == NULL)
 102                 return st->root;
 103
 104         composed = ewah_pool_new();
 105         parent = lookup_stored_bitmap(st->xor);
 106         ewah_xor(st->root, parent, composed);
 107
 108         ewah_pool_free(st->root);
 109         st->root = composed;
 110         st->xor = NULL;
 111
 112         return composed;
 113 }
 114
 115 /*
 116  * Read a bitmap from the current read position on the mmaped
 117  * index, and increase the read position accordingly
 118  */
 119 static struct ewah_bitmap *read_bitmap_1(struct bitmap_index *index)
 120 {
 121         struct ewah_bitmap *b = ewah_pool_new();
 122
 123         ssize_t bitmap_size = ewah_read_mmap(b,
 124                 index->map + index->map_pos,
 125                 index->map_size - index->map_pos);
 126
 127         if (bitmap_size < 0) {
 128                 error("Failed to load bitmap index (corrupted?)");
 129                 ewah_pool_free(b);
 130                 return NULL;
 131         }
 132
 133         index->map_pos += bitmap_size;
 134         return b;
 135 }
 136
 137 static int load_bitmap_header(struct bitmap_index *index)
 138 {
 139         struct bitmap_disk_header *header = (void *)index->map;
 140
 141         if (index->map_size < sizeof(*header) + the_hash_algo->rawsz)
 142                 return error("Corrupted bitmap index (missing header data)");
 143
 144         if (memcmp(header->magic, BITMAP_IDX_SIGNATURE, sizeof(BITMAP_IDX_SIGNATURE)) != 0)
 145                 return error("Corrupted bitmap index file (wrong header)");
 146
 147         index->version = ntohs(header->version);
 148         if (index->version != 1)
 149                 return error("Unsupported version for bitmap index file (%d)", index->version);
 150
 151         /* Parse known bitmap format options */
 152         {
 153                 uint32_t flags = ntohs(header->options);
 154
 155                 if ((flags & BITMAP_OPT_FULL_DAG) == 0)
 156                         return error("Unsupported options for bitmap index file "
 157                                 "(Git requires BITMAP_OPT_FULL_DAG)");
 158
 159                 if (flags & BITMAP_OPT_HASH_CACHE) {
 160                         unsigned char *end = index->map + index->map_size - the_hash_algo->rawsz;
 161                         index->hashes = ((uint32_t *)end) - index->pack->num_objects;
 162                 }
 163         }
 164
 165         index->entry_count = ntohl(header->entry_count);
 166         index->map_pos += sizeof(*header) - GIT_MAX_RAWSZ + the_hash_algo->rawsz;
 167         return 0;
 168 }
 169
 170 static struct stored_bitmap *store_bitmap(struct bitmap_index *index,
 171                                           struct ewah_bitmap *root,
 172                                           const unsigned char *hash,
 173                                           struct stored_bitmap *xor_with,
 174                                           int flags)
 175 {
 176         struct stored_bitmap *stored;
 177         khiter_t hash_pos;
 178         int ret;
 179
 180         stored = xmalloc(sizeof(struct stored_bitmap));
 181         stored->root = root;
 182         stored->xor = xor_with;
 183         stored->flags = flags;
 184         oidread(&stored->oid, hash);
 185
 186         hash_pos = kh_put_oid_map(index->bitmaps, stored->oid, &ret);
 187
 188         /* a 0 return code means the insertion succeeded with no changes,
 189          * because the SHA1 already existed on the map. this is bad, there
 190          * shouldn't be duplicated commits in the index */
 191         if (ret == 0) {
 192                 error("Duplicate entry in bitmap index: %s", hash_to_hex(hash));
 193                 return NULL;
 194         }
 195
 196         kh_value(index->bitmaps, hash_pos) = stored;
 197         return stored;
 198 }
 199
 200 static inline uint32_t read_be32(const unsigned char *buffer, size_t *pos)
 201 {
 202         uint32_t result = get_be32(buffer + *pos);
 203         (*pos) += sizeof(result);
 204         return result;
 205 }
 206
 207 static inline uint8_t read_u8(const unsigned char *buffer, size_t *pos)
 208 {
 209         return buffer[(*pos)++];
 210 }
 211
 212 #define MAX_XOR_OFFSET 160
 213
 214 static int load_bitmap_entries_v1(struct bitmap_index *index)
 215 {
 216         uint32_t i;
 217         struct stored_bitmap *recent_bitmaps[MAX_XOR_OFFSET] = { NULL };
 218
 219         for (i = 0; i < index->entry_count; ++i) {
 220                 int xor_offset, flags;
 221                 struct ewah_bitmap *bitmap = NULL;
 222                 struct stored_bitmap *xor_bitmap = NULL;
 223                 uint32_t commit_idx_pos;
 224                 const unsigned char *sha1;
 225
 226                 commit_idx_pos = read_be32(index->map, &index->map_pos);
 227                 xor_offset = read_u8(index->map, &index->map_pos);
 228                 flags = read_u8(index->map, &index->map_pos);
 229
 230                 sha1 = nth_packed_object_sha1(index->pack, commit_idx_pos);
 231
 232                 bitmap = read_bitmap_1(index);
 233                 if (!bitmap)
 234                         return -1;
 235
 236                 if (xor_offset > MAX_XOR_OFFSET || xor_offset > i)
 237                         return error("Corrupted bitmap pack index");
 238
 239                 if (xor_offset > 0) {
 240                         xor_bitmap = recent_bitmaps[(i - xor_offset) % MAX_XOR_OFFSET];
 241
 242                         if (xor_bitmap == NULL)
 243                                 return error("Invalid XOR offset in bitmap pack index");
 244                 }
 245
 246                 recent_bitmaps[i % MAX_XOR_OFFSET] = store_bitmap(
 247                         index, bitmap, sha1, xor_bitmap, flags);
 248         }
 249
 250         return 0;
 251 }
 252
 253 static char *pack_bitmap_filename(struct packed_git *p)
 254 {
 255         size_t len;
 256
 257         if (!strip_suffix(p->pack_name, ".pack", &len))
 258                 BUG("pack_name does not end in .pack");
 259         return xstrfmt("%.*s.bitmap", (int)len, p->pack_name);
 260 }
 261
 262 static int open_pack_bitmap_1(struct bitmap_index *bitmap_git, struct packed_git *packfile)
 263 {
 264         int fd;
 265         struct stat st;
 266         char *idx_name;
 267
 268         if (open_pack_index(packfile))
 269                 return -1;
 270
 271         idx_name = pack_bitmap_filename(packfile);
 272         fd = git_open(idx_name);
 273         free(idx_name);
 274
 275         if (fd < 0)
 276                 return -1;
 277
 278         if (fstat(fd, &st)) {
 279                 close(fd);
 280                 return -1;
 281         }
 282
 283         if (bitmap_git->pack) {
 284                 warning("ignoring extra bitmap file: %s", packfile->pack_name);
 285                 close(fd);
 286                 return -1;
 287         }
 288
 289         bitmap_git->pack = packfile;
 290         bitmap_git->map_size = xsize_t(st.st_size);
 291         bitmap_git->map = xmmap(NULL, bitmap_git->map_size, PROT_READ, MAP_PRIVATE, fd, 0);
 292         bitmap_git->map_pos = 0;
 293         close(fd);
 294
 295         if (load_bitmap_header(bitmap_git) < 0) {
 296                 munmap(bitmap_git->map, bitmap_git->map_size);
 297                 bitmap_git->map = NULL;
 298                 bitmap_git->map_size = 0;
 299                 return -1;
 300         }
 301
 302         return 0;
 303 }
 304
 305 static int load_pack_bitmap(struct bitmap_index *bitmap_git)
 306 {
 307         assert(bitmap_git->map);
 308
 309         bitmap_git->bitmaps = kh_init_oid_map();
 310         bitmap_git->ext_index.positions = kh_init_oid_pos();
 311         if (load_pack_revindex(bitmap_git->pack))
 312                 goto failed;
 313
 314         if (!(bitmap_git->commits = read_bitmap_1(bitmap_git)) ||
 315                 !(bitmap_git->trees = read_bitmap_1(bitmap_git)) ||
 316                 !(bitmap_git->blobs = read_bitmap_1(bitmap_git)) ||
 317                 !(bitmap_git->tags = read_bitmap_1(bitmap_git)))
 318                 goto failed;
 319
 320         if (load_bitmap_entries_v1(bitmap_git) < 0)
 321                 goto failed;
 322
 323         return 0;
 324
 325 failed:
 326         munmap(bitmap_git->map, bitmap_git->map_size);
 327         bitmap_git->map = NULL;
 328         bitmap_git->map_size = 0;
 329         return -1;
 330 }
 331
 332 static int open_pack_bitmap(struct repository *r,
 333                             struct bitmap_index *bitmap_git)
 334 {
 335         struct packed_git *p;
 336         int ret = -1;
 337
 338         assert(!bitmap_git->map);
 339
 340         for (p = get_all_packs(r); p; p = p->next) {
 341                 if (open_pack_bitmap_1(bitmap_git, p) == 0)
 342                         ret = 0;
 343         }
 344
 345         return ret;
 346 }
 347
 348 struct bitmap_index *prepare_bitmap_git(struct repository *r)
 349 {
 350         struct bitmap_index *bitmap_git = xcalloc(1, sizeof(*bitmap_git));
 351
 352         if (!open_pack_bitmap(r, bitmap_git) && !load_pack_bitmap(bitmap_git))
 353                 return bitmap_git;
 354
 355         free_bitmap_index(bitmap_git);
 356         return NULL;
 357 }
 358
 359 struct include_data {
 360         struct bitmap_index *bitmap_git;
 361         struct bitmap *base;
 362         struct bitmap *seen;
 363 };
 364
 365 static inline int bitmap_position_extended(struct bitmap_index *bitmap_git,
 366                                            const struct object_id *oid)
 367 {
 368         kh_oid_pos_t *positions = bitmap_git->ext_index.positions;
 369         khiter_t pos = kh_get_oid_pos(positions, *oid);
 370
 371         if (pos < kh_end(positions)) {
 372                 int bitmap_pos = kh_value(positions, pos);
 373                 return bitmap_pos + bitmap_git->pack->num_objects;
 374         }
 375
 376         return -1;
 377 }
 378
 379 static inline int bitmap_position_packfile(struct bitmap_index *bitmap_git,
 380                                            const struct object_id *oid)
 381 {
 382         off_t offset = find_pack_entry_one(oid->hash, bitmap_git->pack);
 383         if (!offset)
 384                 return -1;
 385
 386         return find_revindex_position(bitmap_git->pack, offset);
 387 }
 388
 389 static int bitmap_position(struct bitmap_index *bitmap_git,
 390                            const struct object_id *oid)
 391 {
 392         int pos = bitmap_position_packfile(bitmap_git, oid);
 393         return (pos >= 0) ? pos : bitmap_position_extended(bitmap_git, oid);
 394 }
 395
 396 static int ext_index_add_object(struct bitmap_index *bitmap_git,
 397                                 struct object *object, const char *name)
 398 {
 399         struct eindex *eindex = &bitmap_git->ext_index;
 400
 401         khiter_t hash_pos;
 402         int hash_ret;
 403         int bitmap_pos;
 404
 405         hash_pos = kh_put_oid_pos(eindex->positions, object->oid, &hash_ret);
 406         if (hash_ret > 0) {
 407                 if (eindex->count >= eindex->alloc) {
 408                         eindex->alloc = (eindex->alloc + 16) * 3 / 2;
 409                         REALLOC_ARRAY(eindex->objects, eindex->alloc);
 410                         REALLOC_ARRAY(eindex->hashes, eindex->alloc);
 411                 }
 412
 413                 bitmap_pos = eindex->count;
 414                 eindex->objects[eindex->count] = object;
 415                 eindex->hashes[eindex->count] = pack_name_hash(name);
 416                 kh_value(eindex->positions, hash_pos) = bitmap_pos;
 417                 eindex->count++;
 418         } else {
 419                 bitmap_pos = kh_value(eindex->positions, hash_pos);
 420         }
 421
 422         return bitmap_pos + bitmap_git->pack->num_objects;
 423 }
 424
 425 struct bitmap_show_data {
 426         struct bitmap_index *bitmap_git;
 427         struct bitmap *base;
 428 };
 429
 430 static void show_object(struct object *object, const char *name, void *data_)
 431 {
 432         struct bitmap_show_data *data = data_;
 433         int bitmap_pos;
 434
 435         bitmap_pos = bitmap_position(data->bitmap_git, &object->oid);
 436
 437         if (bitmap_pos < 0)
 438                 bitmap_pos = ext_index_add_object(data->bitmap_git, object,
 439                                                   name);
 440
 441         bitmap_set(data->base, bitmap_pos);
 442 }
 443
 444 static void show_commit(struct commit *commit, void *data)
 445 {
 446 }
 447
 448 static int add_to_include_set(struct bitmap_index *bitmap_git,
 449                               struct include_data *data,
 450                               const struct object_id *oid,
 451                               int bitmap_pos)
 452 {
 453         khiter_t hash_pos;
 454
 455         if (data->seen && bitmap_get(data->seen, bitmap_pos))
 456                 return 0;
 457
 458         if (bitmap_get(data->base, bitmap_pos))
 459                 return 0;
 460
 461         hash_pos = kh_get_oid_map(bitmap_git->bitmaps, *oid);
 462         if (hash_pos < kh_end(bitmap_git->bitmaps)) {
 463                 struct stored_bitmap *st = kh_value(bitmap_git->bitmaps, hash_pos);
 464                 bitmap_or_ewah(data->base, lookup_stored_bitmap(st));
 465                 return 0;
 466         }
 467
 468         bitmap_set(data->base, bitmap_pos);
 469         return 1;
 470 }
 471
 472 static int should_include(struct commit *commit, void *_data)
 473 {
 474         struct include_data *data = _data;
 475         int bitmap_pos;
 476
 477         bitmap_pos = bitmap_position(data->bitmap_git, &commit->object.oid);
 478         if (bitmap_pos < 0)
 479                 bitmap_pos = ext_index_add_object(data->bitmap_git,
 480                                                   (struct object *)commit,
 481                                                   NULL);
 482
 483         if (!add_to_include_set(data->bitmap_git, data, &commit->object.oid,
 484                                 bitmap_pos)) {
 485                 struct commit_list *parent = commit->parents;
 486
 487                 while (parent) {
 488                         parent->item->object.flags |= SEEN;
 489                         parent = parent->next;
 490                 }
 491
 492                 return 0;
 493         }
 494
 495         return 1;
 496 }
 497
 498 static struct bitmap *find_objects(struct bitmap_index *bitmap_git,
 499                                    struct rev_info *revs,
 500                                    struct object_list *roots,
 501                                    struct bitmap *seen)
 502 {
 503         struct bitmap *base = NULL;
 504         int needs_walk = 0;
 505
 506         struct object_list *not_mapped = NULL;
 507
 508         /*
 509          * Go through all the roots for the walk. The ones that have bitmaps
 510          * on the bitmap index will be `or`ed together to form an initial
 511          * global reachability analysis.
 512          *
 513          * The ones without bitmaps in the index will be stored in the
 514          * `not_mapped_list` for further processing.
 515          */
 516         while (roots) {
 517                 struct object *object = roots->item;
 518                 roots = roots->next;
 519
 520                 if (object->type == OBJ_COMMIT) {
 521                         khiter_t pos = kh_get_oid_map(bitmap_git->bitmaps, object->oid);
 522
 523                         if (pos < kh_end(bitmap_git->bitmaps)) {
 524                                 struct stored_bitmap *st = kh_value(bitmap_git->bitmaps, pos);
 525                                 struct ewah_bitmap *or_with = lookup_stored_bitmap(st);
 526
 527                                 if (base == NULL)
 528                                         base = ewah_to_bitmap(or_with);
 529                                 else
 530                                         bitmap_or_ewah(base, or_with);
 531
 532                                 object->flags |= SEEN;
 533                                 continue;
 534                         }
 535                 }
 536
 537                 object_list_insert(object, &not_mapped);
 538         }
 539
 540         /*
 541          * Best case scenario: We found bitmaps for all the roots,
 542          * so the resulting `or` bitmap has the full reachability analysis
 543          */
 544         if (not_mapped == NULL)
 545                 return base;
 546
 547         roots = not_mapped;
 548
 549         /*
 550          * Let's iterate through all the roots that don't have bitmaps to
 551          * check if we can determine them to be reachable from the existing
 552          * global bitmap.
 553          *
 554          * If we cannot find them in the existing global bitmap, we'll need
 555          * to push them to an actual walk and run it until we can confirm
 556          * they are reachable
 557          */
 558         while (roots) {
 559                 struct object *object = roots->item;
 560                 int pos;
 561
 562                 roots = roots->next;
 563                 pos = bitmap_position(bitmap_git, &object->oid);
 564
 565                 if (pos < 0 || base == NULL || !bitmap_get(base, pos)) {
 566                         object->flags &= ~UNINTERESTING;
 567                         add_pending_object(revs, object, "");
 568                         needs_walk = 1;
 569                 } else {
 570                         object->flags |= SEEN;
 571                 }
 572         }
 573
 574         if (needs_walk) {
 575                 struct include_data incdata;
 576                 struct bitmap_show_data show_data;
 577
 578                 if (base == NULL)
 579                         base = bitmap_new();
 580
 581                 incdata.bitmap_git = bitmap_git;
 582                 incdata.base = base;
 583                 incdata.seen = seen;
 584
 585                 revs->include_check = should_include;
 586                 revs->include_check_data = &incdata;
 587
 588                 if (prepare_revision_walk(revs))
 589                         die("revision walk setup failed");
 590
 591                 show_data.bitmap_git = bitmap_git;
 592                 show_data.base = base;
 593
 594                 traverse_commit_list(revs, show_commit, show_object,
 595                                      &show_data);
 596         }
 597
 598         return base;
 599 }
 600
 601 static void show_extended_objects(struct bitmap_index *bitmap_git,
 602                                   show_reachable_fn show_reach)
 603 {
 604         struct bitmap *objects = bitmap_git->result;
 605         struct eindex *eindex = &bitmap_git->ext_index;
 606         uint32_t i;
 607
 608         for (i = 0; i < eindex->count; ++i) {
 609                 struct object *obj;
 610
 611                 if (!bitmap_get(objects, bitmap_git->pack->num_objects + i))
 612                         continue;
 613
 614                 obj = eindex->objects[i];
 615                 show_reach(&obj->oid, obj->type, 0, eindex->hashes[i], NULL, 0);
 616         }
 617 }
 618
 619 static void init_type_iterator(struct ewah_iterator *it,
 620                                struct bitmap_index *bitmap_git,
 621                                enum object_type type)
 622 {
 623         switch (type) {
 624         case OBJ_COMMIT:
 625                 ewah_iterator_init(it, bitmap_git->commits);
 626                 break;
 627
 628         case OBJ_TREE:
 629                 ewah_iterator_init(it, bitmap_git->trees);
 630                 break;
 631
 632         case OBJ_BLOB:
 633                 ewah_iterator_init(it, bitmap_git->blobs);
 634                 break;
 635
 636         case OBJ_TAG:
 637                 ewah_iterator_init(it, bitmap_git->tags);
 638                 break;
 639
 640         default:
 641                 BUG("object type %d not stored by bitmap type index", type);
 642                 break;
 643         }
 644 }
 645
 646 static void show_objects_for_type(
 647         struct bitmap_index *bitmap_git,
 648         enum object_type object_type,
 649         show_reachable_fn show_reach)
 650 {
 651         size_t pos = 0, i = 0;
 652         uint32_t offset;
 653
 654         struct ewah_iterator it;
 655         eword_t filter;
 656
 657         struct bitmap *objects = bitmap_git->result;
 658
 659         if (bitmap_git->reuse_objects == bitmap_git->pack->num_objects)
 660                 return;
 661
 662         init_type_iterator(&it, bitmap_git, object_type);
 663
 664         while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) {
 665                 eword_t word = objects->words[i] & filter;
 666
 667                 for (offset = 0; offset < BITS_IN_EWORD; ++offset) {
 668                         struct object_id oid;
 669                         struct revindex_entry *entry;
 670                         uint32_t hash = 0;
 671
 672                         if ((word >> offset) == 0)
 673                                 break;
 674
 675                         offset += ewah_bit_ctz64(word >> offset);
 676
 677                         if (pos + offset < bitmap_git->reuse_objects)
 678                                 continue;
 679
 680                         entry = &bitmap_git->pack->revindex[pos + offset];
 681                         nth_packed_object_oid(&oid, bitmap_git->pack, entry->nr);
 682
 683                         if (bitmap_git->hashes)
 684                                 hash = get_be32(bitmap_git->hashes + entry->nr);
 685
 686                         show_reach(&oid, object_type, 0, hash, bitmap_git->pack, entry->offset);
 687                 }
 688
 689                 pos += BITS_IN_EWORD;
 690                 i++;
 691         }
 692 }
 693
 694 static int in_bitmapped_pack(struct bitmap_index *bitmap_git,
 695                              struct object_list *roots)
 696 {
 697         while (roots) {
 698                 struct object *object = roots->item;
 699                 roots = roots->next;
 700
 701                 if (find_pack_entry_one(object->oid.hash, bitmap_git->pack) > 0)
 702                         return 1;
 703         }
 704
 705         return 0;
 706 }
 707
 708 struct bitmap_index *prepare_bitmap_walk(struct rev_info *revs)
 709 {
 710         unsigned int i;
 711
 712         struct object_list *wants = NULL;
 713         struct object_list *haves = NULL;
 714
 715         struct bitmap *wants_bitmap = NULL;
 716         struct bitmap *haves_bitmap = NULL;
 717
 718         struct bitmap_index *bitmap_git;
 719
 720         /*
 721          * We can't do pathspec limiting with bitmaps, because we don't know
 722          * which commits are associated with which object changes (let alone
 723          * even which objects are associated with which paths).
 724          */
 725         if (revs->prune)
 726                 return NULL;
 727
 728         /* try to open a bitmapped pack, but don't parse it yet
 729          * because we may not need to use it */
 730         bitmap_git = xcalloc(1, sizeof(*bitmap_git));
 731         if (open_pack_bitmap(revs->repo, bitmap_git) < 0)
 732                 goto cleanup;
 733
 734         for (i = 0; i < revs->pending.nr; ++i) {
 735                 struct object *object = revs->pending.objects[i].item;
 736
 737                 if (object->type == OBJ_NONE)
 738                         parse_object_or_die(&object->oid, NULL);
 739
 740                 while (object->type == OBJ_TAG) {
 741                         struct tag *tag = (struct tag *) object;
 742
 743                         if (object->flags & UNINTERESTING)
 744                                 object_list_insert(object, &haves);
 745                         else
 746                                 object_list_insert(object, &wants);
 747
 748                         object = parse_object_or_die(get_tagged_oid(tag), NULL);
 749                 }
 750
 751                 if (object->flags & UNINTERESTING)
 752                         object_list_insert(object, &haves);
 753                 else
 754                         object_list_insert(object, &wants);
 755         }
 756
 757         /*
 758          * if we have a HAVES list, but none of those haves is contained
 759          * in the packfile that has a bitmap, we don't have anything to
 760          * optimize here
 761          */
 762         if (haves && !in_bitmapped_pack(bitmap_git, haves))
 763                 goto cleanup;
 764
 765         /* if we don't want anything, we're done here */
 766         if (!wants)
 767                 goto cleanup;
 768
 769         /*
 770          * now we're going to use bitmaps, so load the actual bitmap entries
 771          * from disk. this is the point of no return; after this the rev_list
 772          * becomes invalidated and we must perform the revwalk through bitmaps
 773          */
 774         if (load_pack_bitmap(bitmap_git) < 0)
 775                 goto cleanup;
 776
 777         object_array_clear(&revs->pending);
 778
 779         if (haves) {
 780                 revs->ignore_missing_links = 1;
 781                 haves_bitmap = find_objects(bitmap_git, revs, haves, NULL);
 782                 reset_revision_walk();
 783                 revs->ignore_missing_links = 0;
 784
 785                 if (haves_bitmap == NULL)
 786                         BUG("failed to perform bitmap walk");
 787         }
 788
 789         wants_bitmap = find_objects(bitmap_git, revs, wants, haves_bitmap);
 790
 791         if (!wants_bitmap)
 792                 BUG("failed to perform bitmap walk");
 793
 794         if (haves_bitmap)
 795                 bitmap_and_not(wants_bitmap, haves_bitmap);
 796
 797         bitmap_git->result = wants_bitmap;
 798         bitmap_git->haves = haves_bitmap;
 799
 800         object_list_free(&wants);
 801         object_list_free(&haves);
 802
 803         return bitmap_git;
 804
 805 cleanup:
 806         free_bitmap_index(bitmap_git);
 807         object_list_free(&wants);
 808         object_list_free(&haves);
 809         return NULL;
 810 }
 811
 812 int reuse_partial_packfile_from_bitmap(struct bitmap_index *bitmap_git,
 813                                        struct packed_git **packfile,
 814                                        uint32_t *entries,
 815                                        off_t *up_to)
 816 {
 817         /*
 818          * Reuse the packfile content if we need more than
 819          * 90% of its objects
 820          */
 821         static const double REUSE_PERCENT = 0.9;
 822
 823         struct bitmap *result = bitmap_git->result;
 824         uint32_t reuse_threshold;
 825         uint32_t i, reuse_objects = 0;
 826
 827         assert(result);
 828
 829         for (i = 0; i < result->word_alloc; ++i) {
 830                 if (result->words[i] != (eword_t)~0) {
 831                         reuse_objects += ewah_bit_ctz64(~result->words[i]);
 832                         break;
 833                 }
 834
 835                 reuse_objects += BITS_IN_EWORD;
 836         }
 837
 838 #ifdef GIT_BITMAP_DEBUG
 839         {
 840                 const unsigned char *sha1;
 841                 struct revindex_entry *entry;
 842
 843                 entry = &bitmap_git->reverse_index->revindex[reuse_objects];
 844                 sha1 = nth_packed_object_sha1(bitmap_git->pack, entry->nr);
 845
 846                 fprintf(stderr, "Failed to reuse at %d (%016llx)\n",
 847                         reuse_objects, result->words[i]);
 848                 fprintf(stderr, " %s\n", hash_to_hex(sha1));
 849         }
 850 #endif
 851
 852         if (!reuse_objects)
 853                 return -1;
 854
 855         if (reuse_objects >= bitmap_git->pack->num_objects) {
 856                 bitmap_git->reuse_objects = *entries = bitmap_git->pack->num_objects;
 857                 *up_to = -1; /* reuse the full pack */
 858                 *packfile = bitmap_git->pack;
 859                 return 0;
 860         }
 861
 862         reuse_threshold = bitmap_popcount(bitmap_git->result) * REUSE_PERCENT;
 863
 864         if (reuse_objects < reuse_threshold)
 865                 return -1;
 866
 867         bitmap_git->reuse_objects = *entries = reuse_objects;
 868         *up_to = bitmap_git->pack->revindex[reuse_objects].offset;
 869         *packfile = bitmap_git->pack;
 870
 871         return 0;
 872 }
 873
 874 void traverse_bitmap_commit_list(struct bitmap_index *bitmap_git,
 875                                  show_reachable_fn show_reachable)
 876 {
 877         assert(bitmap_git->result);
 878
 879         show_objects_for_type(bitmap_git, OBJ_COMMIT, show_reachable);
 880         show_objects_for_type(bitmap_git, OBJ_TREE, show_reachable);
 881         show_objects_for_type(bitmap_git, OBJ_BLOB, show_reachable);
 882         show_objects_for_type(bitmap_git, OBJ_TAG, show_reachable);
 883
 884         show_extended_objects(bitmap_git, show_reachable);
 885 }
 886
 887 static uint32_t count_object_type(struct bitmap_index *bitmap_git,
 888                                   enum object_type type)
 889 {
 890         struct bitmap *objects = bitmap_git->result;
 891         struct eindex *eindex = &bitmap_git->ext_index;
 892
 893         uint32_t i = 0, count = 0;
 894         struct ewah_iterator it;
 895         eword_t filter;
 896
 897         init_type_iterator(&it, bitmap_git, type);
 898
 899         while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) {
 900                 eword_t word = objects->words[i++] & filter;
 901                 count += ewah_bit_popcount64(word);
 902         }
 903
 904         for (i = 0; i < eindex->count; ++i) {
 905                 if (eindex->objects[i]->type == type &&
 906                         bitmap_get(objects, bitmap_git->pack->num_objects + i))
 907                         count++;
 908         }
 909
 910         return count;
 911 }
 912
 913 void count_bitmap_commit_list(struct bitmap_index *bitmap_git,
 914                               uint32_t *commits, uint32_t *trees,
 915                               uint32_t *blobs, uint32_t *tags)
 916 {
 917         assert(bitmap_git->result);
 918
 919         if (commits)
 920                 *commits = count_object_type(bitmap_git, OBJ_COMMIT);
 921
 922         if (trees)
 923                 *trees = count_object_type(bitmap_git, OBJ_TREE);
 924
 925         if (blobs)
 926                 *blobs = count_object_type(bitmap_git, OBJ_BLOB);
 927
 928         if (tags)
 929                 *tags = count_object_type(bitmap_git, OBJ_TAG);
 930 }
 931
 932 struct bitmap_test_data {
 933         struct bitmap_index *bitmap_git;
 934         struct bitmap *base;
 935         struct progress *prg;
 936         size_t seen;
 937 };
 938
 939 static void test_show_object(struct object *object, const char *name,
 940                              void *data)
 941 {
 942         struct bitmap_test_data *tdata = data;
 943         int bitmap_pos;
 944
 945         bitmap_pos = bitmap_position(tdata->bitmap_git, &object->oid);
 946         if (bitmap_pos < 0)
 947                 die("Object not in bitmap: %s\n", oid_to_hex(&object->oid));
 948
 949         bitmap_set(tdata->base, bitmap_pos);
 950         display_progress(tdata->prg, ++tdata->seen);
 951 }
 952
 953 static void test_show_commit(struct commit *commit, void *data)
 954 {
 955         struct bitmap_test_data *tdata = data;
 956         int bitmap_pos;
 957
 958         bitmap_pos = bitmap_position(tdata->bitmap_git,
 959                                      &commit->object.oid);
 960         if (bitmap_pos < 0)
 961                 die("Object not in bitmap: %s\n", oid_to_hex(&commit->object.oid));
 962
 963         bitmap_set(tdata->base, bitmap_pos);
 964         display_progress(tdata->prg, ++tdata->seen);
 965 }
 966
 967 void test_bitmap_walk(struct rev_info *revs)
 968 {
 969         struct object *root;
 970         struct bitmap *result = NULL;
 971         khiter_t pos;
 972         size_t result_popcnt;
 973         struct bitmap_test_data tdata;
 974         struct bitmap_index *bitmap_git;
 975
 976         if (!(bitmap_git = prepare_bitmap_git(revs->repo)))
 977                 die("failed to load bitmap indexes");
 978
 979         if (revs->pending.nr != 1)
 980                 die("you must specify exactly one commit to test");
 981
 982         fprintf(stderr, "Bitmap v%d test (%d entries loaded)\n",
 983                 bitmap_git->version, bitmap_git->entry_count);
 984
 985         root = revs->pending.objects[0].item;
 986         pos = kh_get_oid_map(bitmap_git->bitmaps, root->oid);
 987
 988         if (pos < kh_end(bitmap_git->bitmaps)) {
 989                 struct stored_bitmap *st = kh_value(bitmap_git->bitmaps, pos);
 990                 struct ewah_bitmap *bm = lookup_stored_bitmap(st);
 991
 992                 fprintf(stderr, "Found bitmap for %s. %d bits / %08x checksum\n",
 993                         oid_to_hex(&root->oid), (int)bm->bit_size, ewah_checksum(bm));
 994
 995                 result = ewah_to_bitmap(bm);
 996         }
 997
 998         if (result == NULL)
 999                 die("Commit %s doesn't have an indexed bitmap", oid_to_hex(&root->oid));
1000
1001         revs->tag_objects = 1;
1002         revs->tree_objects = 1;
1003         revs->blob_objects = 1;
1004
1005         result_popcnt = bitmap_popcount(result);
1006
1007         if (prepare_revision_walk(revs))
1008                 die("revision walk setup failed");
1009
1010         tdata.bitmap_git = bitmap_git;
1011         tdata.base = bitmap_new();
1012         tdata.prg = start_progress("Verifying bitmap entries", result_popcnt);
1013         tdata.seen = 0;
1014
1015         traverse_commit_list(revs, &test_show_commit, &test_show_object, &tdata);
1016
1017         stop_progress(&tdata.prg);
1018
1019         if (bitmap_equals(result, tdata.base))
1020                 fprintf(stderr, "OK!\n");
1021         else
1022                 fprintf(stderr, "Mismatch!\n");
1023
1024         free_bitmap_index(bitmap_git);
1025 }
1026
1027 static int rebuild_bitmap(uint32_t *reposition,
1028                           struct ewah_bitmap *source,
1029                           struct bitmap *dest)
1030 {
1031         uint32_t pos = 0;
1032         struct ewah_iterator it;
1033         eword_t word;
1034
1035         ewah_iterator_init(&it, source);
1036
1037         while (ewah_iterator_next(&word, &it)) {
1038                 uint32_t offset, bit_pos;
1039
1040                 for (offset = 0; offset < BITS_IN_EWORD; ++offset) {
1041                         if ((word >> offset) == 0)
1042                                 break;
1043
1044                         offset += ewah_bit_ctz64(word >> offset);
1045
1046                         bit_pos = reposition[pos + offset];
1047                         if (bit_pos > 0)
1048                                 bitmap_set(dest, bit_pos - 1);
1049                         else /* can't reuse, we don't have the object */
1050                                 return -1;
1051                 }
1052
1053                 pos += BITS_IN_EWORD;
1054         }
1055         return 0;
1056 }
1057
1058 int rebuild_existing_bitmaps(struct bitmap_index *bitmap_git,
1059                              struct packing_data *mapping,
1060                              kh_oid_map_t *reused_bitmaps,
1061                              int show_progress)
1062 {
1063         uint32_t i, num_objects;
1064         uint32_t *reposition;
1065         struct bitmap *rebuild;
1066         struct stored_bitmap *stored;
1067         struct progress *progress = NULL;
1068
1069         khiter_t hash_pos;
1070         int hash_ret;
1071
1072         num_objects = bitmap_git->pack->num_objects;
1073         reposition = xcalloc(num_objects, sizeof(uint32_t));
1074
1075         for (i = 0; i < num_objects; ++i) {
1076                 struct object_id oid;
1077                 struct revindex_entry *entry;
1078                 struct object_entry *oe;
1079
1080                 entry = &bitmap_git->pack->revindex[i];
1081                 nth_packed_object_oid(&oid, bitmap_git->pack, entry->nr);
1082                 oe = packlist_find(mapping, &oid);
1083
1084                 if (oe)
1085                         reposition[i] = oe_in_pack_pos(mapping, oe) + 1;
1086         }
1087
1088         rebuild = bitmap_new();
1089         i = 0;
1090
1091         if (show_progress)
1092                 progress = start_progress("Reusing bitmaps", 0);
1093
1094         kh_foreach_value(bitmap_git->bitmaps, stored, {
1095                 if (stored->flags & BITMAP_FLAG_REUSE) {
1096                         if (!rebuild_bitmap(reposition,
1097                                             lookup_stored_bitmap(stored),
1098                                             rebuild)) {
1099                                 hash_pos = kh_put_oid_map(reused_bitmaps,
1100                                                           stored->oid,
1101                                                           &hash_ret);
1102                                 kh_value(reused_bitmaps, hash_pos) =
1103                                         bitmap_to_ewah(rebuild);
1104                         }
1105                         bitmap_reset(rebuild);
1106                         display_progress(progress, ++i);
1107                 }
1108         });
1109
1110         stop_progress(&progress);
1111
1112         free(reposition);
1113         bitmap_free(rebuild);
1114         return 0;
1115 }
1116
1117 void free_bitmap_index(struct bitmap_index *b)
1118 {
1119         if (!b)
1120                 return;
1121
1122         if (b->map)
1123                 munmap(b->map, b->map_size);
1124         ewah_pool_free(b->commits);
1125         ewah_pool_free(b->trees);
1126         ewah_pool_free(b->blobs);
1127         ewah_pool_free(b->tags);
1128         kh_destroy_oid_map(b->bitmaps);
1129         free(b->ext_index.objects);
1130         free(b->ext_index.hashes);
1131         bitmap_free(b->result);
1132         bitmap_free(b->haves);
1133         free(b);
1134 }
1135
1136 int bitmap_has_oid_in_uninteresting(struct bitmap_index *bitmap_git,
1137                                     const struct object_id *oid)
1138 {
1139         int pos;
1140
1141         if (!bitmap_git)
1142                 return 0; /* no bitmap loaded */
1143         if (!bitmap_git->haves)
1144                 return 0; /* walk had no "haves" */
1145
1146         pos = bitmap_position_packfile(bitmap_git, oid);
1147         if (pos < 0)
1148                 return 0;
1149
1150         return bitmap_get(bitmap_git->haves, pos);
1151 }