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         unsigned char sha1[20];
  22         struct ewah_bitmap *root;
  23         struct stored_bitmap *xor;
  24         int flags;
  25 };
  26
  27 /*
  28  * The currently active bitmap index. 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 static 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 SHA1 -> `stored_bitmap` for all the bitmapped commits */
  64         khash_sha1 *bitmaps;
  65
  66         /* Number of bitmapped commits */
  67         uint32_t entry_count;
  68
  69         /* Name-hash cache (or NULL if not present). */
  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                 khash_sha1_pos *positions;
  84         } ext_index;
  85
  86         /* Bitmap result of the last performed walk */
  87         struct bitmap *result;
  88
  89         /* Version of the bitmap index */
  90         unsigned int version;
  91
  92         unsigned loaded : 1;
  93
  94 } bitmap_git;
  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) + 20)
 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 - 20;
 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);
 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 *sha1,
 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         hashcpy(stored->sha1, sha1);
 185
 186         hash_pos = kh_put_sha1(index->bitmaps, stored->sha1, &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", sha1_to_hex(sha1));
 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 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(void)
 306 {
 307         assert(bitmap_git.map && !bitmap_git.loaded);
 308
 309         bitmap_git.bitmaps = kh_init_sha1();
 310         bitmap_git.ext_index.positions = kh_init_sha1_pos();
 311         load_pack_revindex(bitmap_git.pack);
 312
 313         if (!(bitmap_git.commits = read_bitmap_1(&bitmap_git)) ||
 314                 !(bitmap_git.trees = read_bitmap_1(&bitmap_git)) ||
 315                 !(bitmap_git.blobs = read_bitmap_1(&bitmap_git)) ||
 316                 !(bitmap_git.tags = read_bitmap_1(&bitmap_git)))
 317                 goto failed;
 318
 319         if (load_bitmap_entries_v1(&bitmap_git) < 0)
 320                 goto failed;
 321
 322         bitmap_git.loaded = 1;
 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(void)
 333 {
 334         struct packed_git *p;
 335         int ret = -1;
 336
 337         assert(!bitmap_git.map && !bitmap_git.loaded);
 338
 339         for (p = get_packed_git(the_repository); p; p = p->next) {
 340                 if (open_pack_bitmap_1(p) == 0)
 341                         ret = 0;
 342         }
 343
 344         return ret;
 345 }
 346
 347 int prepare_bitmap_git(void)
 348 {
 349         if (bitmap_git.loaded)
 350                 return 0;
 351
 352         if (!open_pack_bitmap())
 353                 return load_pack_bitmap();
 354
 355         return -1;
 356 }
 357
 358 struct include_data {
 359         struct bitmap *base;
 360         struct bitmap *seen;
 361 };
 362
 363 static inline int bitmap_position_extended(const unsigned char *sha1)
 364 {
 365         khash_sha1_pos *positions = bitmap_git.ext_index.positions;
 366         khiter_t pos = kh_get_sha1_pos(positions, sha1);
 367
 368         if (pos < kh_end(positions)) {
 369                 int bitmap_pos = kh_value(positions, pos);
 370                 return bitmap_pos + bitmap_git.pack->num_objects;
 371         }
 372
 373         return -1;
 374 }
 375
 376 static inline int bitmap_position_packfile(const unsigned char *sha1)
 377 {
 378         off_t offset = find_pack_entry_one(sha1, bitmap_git.pack);
 379         if (!offset)
 380                 return -1;
 381
 382         return find_revindex_position(bitmap_git.pack, offset);
 383 }
 384
 385 static int bitmap_position(const unsigned char *sha1)
 386 {
 387         int pos = bitmap_position_packfile(sha1);
 388         return (pos >= 0) ? pos : bitmap_position_extended(sha1);
 389 }
 390
 391 static int ext_index_add_object(struct object *object, const char *name)
 392 {
 393         struct eindex *eindex = &bitmap_git.ext_index;
 394
 395         khiter_t hash_pos;
 396         int hash_ret;
 397         int bitmap_pos;
 398
 399         hash_pos = kh_put_sha1_pos(eindex->positions, object->oid.hash, &hash_ret);
 400         if (hash_ret > 0) {
 401                 if (eindex->count >= eindex->alloc) {
 402                         eindex->alloc = (eindex->alloc + 16) * 3 / 2;
 403                         REALLOC_ARRAY(eindex->objects, eindex->alloc);
 404                         REALLOC_ARRAY(eindex->hashes, eindex->alloc);
 405                 }
 406
 407                 bitmap_pos = eindex->count;
 408                 eindex->objects[eindex->count] = object;
 409                 eindex->hashes[eindex->count] = pack_name_hash(name);
 410                 kh_value(eindex->positions, hash_pos) = bitmap_pos;
 411                 eindex->count++;
 412         } else {
 413                 bitmap_pos = kh_value(eindex->positions, hash_pos);
 414         }
 415
 416         return bitmap_pos + bitmap_git.pack->num_objects;
 417 }
 418
 419 static void show_object(struct object *object, const char *name, void *data)
 420 {
 421         struct bitmap *base = data;
 422         int bitmap_pos;
 423
 424         bitmap_pos = bitmap_position(object->oid.hash);
 425
 426         if (bitmap_pos < 0)
 427                 bitmap_pos = ext_index_add_object(object, name);
 428
 429         bitmap_set(base, bitmap_pos);
 430 }
 431
 432 static void show_commit(struct commit *commit, void *data)
 433 {
 434 }
 435
 436 static int add_to_include_set(struct include_data *data,
 437                               const unsigned char *sha1,
 438                               int bitmap_pos)
 439 {
 440         khiter_t hash_pos;
 441
 442         if (data->seen && bitmap_get(data->seen, bitmap_pos))
 443                 return 0;
 444
 445         if (bitmap_get(data->base, bitmap_pos))
 446                 return 0;
 447
 448         hash_pos = kh_get_sha1(bitmap_git.bitmaps, sha1);
 449         if (hash_pos < kh_end(bitmap_git.bitmaps)) {
 450                 struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, hash_pos);
 451                 bitmap_or_ewah(data->base, lookup_stored_bitmap(st));
 452                 return 0;
 453         }
 454
 455         bitmap_set(data->base, bitmap_pos);
 456         return 1;
 457 }
 458
 459 static int should_include(struct commit *commit, void *_data)
 460 {
 461         struct include_data *data = _data;
 462         int bitmap_pos;
 463
 464         bitmap_pos = bitmap_position(commit->object.oid.hash);
 465         if (bitmap_pos < 0)
 466                 bitmap_pos = ext_index_add_object((struct object *)commit, NULL);
 467
 468         if (!add_to_include_set(data, commit->object.oid.hash, bitmap_pos)) {
 469                 struct commit_list *parent = commit->parents;
 470
 471                 while (parent) {
 472                         parent->item->object.flags |= SEEN;
 473                         parent = parent->next;
 474                 }
 475
 476                 return 0;
 477         }
 478
 479         return 1;
 480 }
 481
 482 static struct bitmap *find_objects(struct rev_info *revs,
 483                                    struct object_list *roots,
 484                                    struct bitmap *seen)
 485 {
 486         struct bitmap *base = NULL;
 487         int needs_walk = 0;
 488
 489         struct object_list *not_mapped = NULL;
 490
 491         /*
 492          * Go through all the roots for the walk. The ones that have bitmaps
 493          * on the bitmap index will be `or`ed together to form an initial
 494          * global reachability analysis.
 495          *
 496          * The ones without bitmaps in the index will be stored in the
 497          * `not_mapped_list` for further processing.
 498          */
 499         while (roots) {
 500                 struct object *object = roots->item;
 501                 roots = roots->next;
 502
 503                 if (object->type == OBJ_COMMIT) {
 504                         khiter_t pos = kh_get_sha1(bitmap_git.bitmaps, object->oid.hash);
 505
 506                         if (pos < kh_end(bitmap_git.bitmaps)) {
 507                                 struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, pos);
 508                                 struct ewah_bitmap *or_with = lookup_stored_bitmap(st);
 509
 510                                 if (base == NULL)
 511                                         base = ewah_to_bitmap(or_with);
 512                                 else
 513                                         bitmap_or_ewah(base, or_with);
 514
 515                                 object->flags |= SEEN;
 516                                 continue;
 517                         }
 518                 }
 519
 520                 object_list_insert(object, &not_mapped);
 521         }
 522
 523         /*
 524          * Best case scenario: We found bitmaps for all the roots,
 525          * so the resulting `or` bitmap has the full reachability analysis
 526          */
 527         if (not_mapped == NULL)
 528                 return base;
 529
 530         roots = not_mapped;
 531
 532         /*
 533          * Let's iterate through all the roots that don't have bitmaps to
 534          * check if we can determine them to be reachable from the existing
 535          * global bitmap.
 536          *
 537          * If we cannot find them in the existing global bitmap, we'll need
 538          * to push them to an actual walk and run it until we can confirm
 539          * they are reachable
 540          */
 541         while (roots) {
 542                 struct object *object = roots->item;
 543                 int pos;
 544
 545                 roots = roots->next;
 546                 pos = bitmap_position(object->oid.hash);
 547
 548                 if (pos < 0 || base == NULL || !bitmap_get(base, pos)) {
 549                         object->flags &= ~UNINTERESTING;
 550                         add_pending_object(revs, object, "");
 551                         needs_walk = 1;
 552                 } else {
 553                         object->flags |= SEEN;
 554                 }
 555         }
 556
 557         if (needs_walk) {
 558                 struct include_data incdata;
 559
 560                 if (base == NULL)
 561                         base = bitmap_new();
 562
 563                 incdata.base = base;
 564                 incdata.seen = seen;
 565
 566                 revs->include_check = should_include;
 567                 revs->include_check_data = &incdata;
 568
 569                 if (prepare_revision_walk(revs))
 570                         die("revision walk setup failed");
 571
 572                 traverse_commit_list(revs, show_commit, show_object, base);
 573         }
 574
 575         return base;
 576 }
 577
 578 static void show_extended_objects(struct bitmap *objects,
 579                                   show_reachable_fn show_reach)
 580 {
 581         struct eindex *eindex = &bitmap_git.ext_index;
 582         uint32_t i;
 583
 584         for (i = 0; i < eindex->count; ++i) {
 585                 struct object *obj;
 586
 587                 if (!bitmap_get(objects, bitmap_git.pack->num_objects + i))
 588                         continue;
 589
 590                 obj = eindex->objects[i];
 591                 show_reach(&obj->oid, obj->type, 0, eindex->hashes[i], NULL, 0);
 592         }
 593 }
 594
 595 static void show_objects_for_type(
 596         struct bitmap *objects,
 597         struct ewah_bitmap *type_filter,
 598         enum object_type object_type,
 599         show_reachable_fn show_reach)
 600 {
 601         size_t pos = 0, i = 0;
 602         uint32_t offset;
 603
 604         struct ewah_iterator it;
 605         eword_t filter;
 606
 607         if (bitmap_git.reuse_objects == bitmap_git.pack->num_objects)
 608                 return;
 609
 610         ewah_iterator_init(&it, type_filter);
 611
 612         while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) {
 613                 eword_t word = objects->words[i] & filter;
 614
 615                 for (offset = 0; offset < BITS_IN_EWORD; ++offset) {
 616                         struct object_id oid;
 617                         struct revindex_entry *entry;
 618                         uint32_t hash = 0;
 619
 620                         if ((word >> offset) == 0)
 621                                 break;
 622
 623                         offset += ewah_bit_ctz64(word >> offset);
 624
 625                         if (pos + offset < bitmap_git.reuse_objects)
 626                                 continue;
 627
 628                         entry = &bitmap_git.pack->revindex[pos + offset];
 629                         nth_packed_object_oid(&oid, bitmap_git.pack, entry->nr);
 630
 631                         if (bitmap_git.hashes)
 632                                 hash = get_be32(bitmap_git.hashes + entry->nr);
 633
 634                         show_reach(&oid, object_type, 0, hash, bitmap_git.pack, entry->offset);
 635                 }
 636
 637                 pos += BITS_IN_EWORD;
 638                 i++;
 639         }
 640 }
 641
 642 static int in_bitmapped_pack(struct object_list *roots)
 643 {
 644         while (roots) {
 645                 struct object *object = roots->item;
 646                 roots = roots->next;
 647
 648                 if (find_pack_entry_one(object->oid.hash, bitmap_git.pack) > 0)
 649                         return 1;
 650         }
 651
 652         return 0;
 653 }
 654
 655 int prepare_bitmap_walk(struct rev_info *revs)
 656 {
 657         unsigned int i;
 658
 659         struct object_list *wants = NULL;
 660         struct object_list *haves = NULL;
 661
 662         struct bitmap *wants_bitmap = NULL;
 663         struct bitmap *haves_bitmap = NULL;
 664
 665         if (!bitmap_git.loaded) {
 666                 /* try to open a bitmapped pack, but don't parse it yet
 667                  * because we may not need to use it */
 668                 if (open_pack_bitmap() < 0)
 669                         return -1;
 670         }
 671
 672         for (i = 0; i < revs->pending.nr; ++i) {
 673                 struct object *object = revs->pending.objects[i].item;
 674
 675                 if (object->type == OBJ_NONE)
 676                         parse_object_or_die(&object->oid, NULL);
 677
 678                 while (object->type == OBJ_TAG) {
 679                         struct tag *tag = (struct tag *) object;
 680
 681                         if (object->flags & UNINTERESTING)
 682                                 object_list_insert(object, &haves);
 683                         else
 684                                 object_list_insert(object, &wants);
 685
 686                         if (!tag->tagged)
 687                                 die("bad tag");
 688                         object = parse_object_or_die(&tag->tagged->oid, NULL);
 689                 }
 690
 691                 if (object->flags & UNINTERESTING)
 692                         object_list_insert(object, &haves);
 693                 else
 694                         object_list_insert(object, &wants);
 695         }
 696
 697         /*
 698          * if we have a HAVES list, but none of those haves is contained
 699          * in the packfile that has a bitmap, we don't have anything to
 700          * optimize here
 701          */
 702         if (haves && !in_bitmapped_pack(haves))
 703                 return -1;
 704
 705         /* if we don't want anything, we're done here */
 706         if (!wants)
 707                 return -1;
 708
 709         /*
 710          * now we're going to use bitmaps, so load the actual bitmap entries
 711          * from disk. this is the point of no return; after this the rev_list
 712          * becomes invalidated and we must perform the revwalk through bitmaps
 713          */
 714         if (!bitmap_git.loaded && load_pack_bitmap() < 0)
 715                 return -1;
 716
 717         object_array_clear(&revs->pending);
 718
 719         if (haves) {
 720                 revs->ignore_missing_links = 1;
 721                 haves_bitmap = find_objects(revs, haves, NULL);
 722                 reset_revision_walk();
 723                 revs->ignore_missing_links = 0;
 724
 725                 if (haves_bitmap == NULL)
 726                         BUG("failed to perform bitmap walk");
 727         }
 728
 729         wants_bitmap = find_objects(revs, wants, haves_bitmap);
 730
 731         if (!wants_bitmap)
 732                 BUG("failed to perform bitmap walk");
 733
 734         if (haves_bitmap)
 735                 bitmap_and_not(wants_bitmap, haves_bitmap);
 736
 737         bitmap_git.result = wants_bitmap;
 738
 739         bitmap_free(haves_bitmap);
 740         return 0;
 741 }
 742
 743 int reuse_partial_packfile_from_bitmap(struct packed_git **packfile,
 744                                        uint32_t *entries,
 745                                        off_t *up_to)
 746 {
 747         /*
 748          * Reuse the packfile content if we need more than
 749          * 90% of its objects
 750          */
 751         static const double REUSE_PERCENT = 0.9;
 752
 753         struct bitmap *result = bitmap_git.result;
 754         uint32_t reuse_threshold;
 755         uint32_t i, reuse_objects = 0;
 756
 757         assert(result);
 758
 759         for (i = 0; i < result->word_alloc; ++i) {
 760                 if (result->words[i] != (eword_t)~0) {
 761                         reuse_objects += ewah_bit_ctz64(~result->words[i]);
 762                         break;
 763                 }
 764
 765                 reuse_objects += BITS_IN_EWORD;
 766         }
 767
 768 #ifdef GIT_BITMAP_DEBUG
 769         {
 770                 const unsigned char *sha1;
 771                 struct revindex_entry *entry;
 772
 773                 entry = &bitmap_git.reverse_index->revindex[reuse_objects];
 774                 sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
 775
 776                 fprintf(stderr, "Failed to reuse at %d (%016llx)\n",
 777                         reuse_objects, result->words[i]);
 778                 fprintf(stderr, " %s\n", sha1_to_hex(sha1));
 779         }
 780 #endif
 781
 782         if (!reuse_objects)
 783                 return -1;
 784
 785         if (reuse_objects >= bitmap_git.pack->num_objects) {
 786                 bitmap_git.reuse_objects = *entries = bitmap_git.pack->num_objects;
 787                 *up_to = -1; /* reuse the full pack */
 788                 *packfile = bitmap_git.pack;
 789                 return 0;
 790         }
 791
 792         reuse_threshold = bitmap_popcount(bitmap_git.result) * REUSE_PERCENT;
 793
 794         if (reuse_objects < reuse_threshold)
 795                 return -1;
 796
 797         bitmap_git.reuse_objects = *entries = reuse_objects;
 798         *up_to = bitmap_git.pack->revindex[reuse_objects].offset;
 799         *packfile = bitmap_git.pack;
 800
 801         return 0;
 802 }
 803
 804 void traverse_bitmap_commit_list(show_reachable_fn show_reachable)
 805 {
 806         assert(bitmap_git.result);
 807
 808         show_objects_for_type(bitmap_git.result, bitmap_git.commits,
 809                 OBJ_COMMIT, show_reachable);
 810         show_objects_for_type(bitmap_git.result, bitmap_git.trees,
 811                 OBJ_TREE, show_reachable);
 812         show_objects_for_type(bitmap_git.result, bitmap_git.blobs,
 813                 OBJ_BLOB, show_reachable);
 814         show_objects_for_type(bitmap_git.result, bitmap_git.tags,
 815                 OBJ_TAG, show_reachable);
 816
 817         show_extended_objects(bitmap_git.result, show_reachable);
 818
 819         bitmap_free(bitmap_git.result);
 820         bitmap_git.result = NULL;
 821 }
 822
 823 static uint32_t count_object_type(struct bitmap *objects,
 824                                   enum object_type type)
 825 {
 826         struct eindex *eindex = &bitmap_git.ext_index;
 827
 828         uint32_t i = 0, count = 0;
 829         struct ewah_iterator it;
 830         eword_t filter;
 831
 832         switch (type) {
 833         case OBJ_COMMIT:
 834                 ewah_iterator_init(&it, bitmap_git.commits);
 835                 break;
 836
 837         case OBJ_TREE:
 838                 ewah_iterator_init(&it, bitmap_git.trees);
 839                 break;
 840
 841         case OBJ_BLOB:
 842                 ewah_iterator_init(&it, bitmap_git.blobs);
 843                 break;
 844
 845         case OBJ_TAG:
 846                 ewah_iterator_init(&it, bitmap_git.tags);
 847                 break;
 848
 849         default:
 850                 return 0;
 851         }
 852
 853         while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) {
 854                 eword_t word = objects->words[i++] & filter;
 855                 count += ewah_bit_popcount64(word);
 856         }
 857
 858         for (i = 0; i < eindex->count; ++i) {
 859                 if (eindex->objects[i]->type == type &&
 860                         bitmap_get(objects, bitmap_git.pack->num_objects + i))
 861                         count++;
 862         }
 863
 864         return count;
 865 }
 866
 867 void count_bitmap_commit_list(uint32_t *commits, uint32_t *trees,
 868                               uint32_t *blobs, uint32_t *tags)
 869 {
 870         assert(bitmap_git.result);
 871
 872         if (commits)
 873                 *commits = count_object_type(bitmap_git.result, OBJ_COMMIT);
 874
 875         if (trees)
 876                 *trees = count_object_type(bitmap_git.result, OBJ_TREE);
 877
 878         if (blobs)
 879                 *blobs = count_object_type(bitmap_git.result, OBJ_BLOB);
 880
 881         if (tags)
 882                 *tags = count_object_type(bitmap_git.result, OBJ_TAG);
 883 }
 884
 885 struct bitmap_test_data {
 886         struct bitmap *base;
 887         struct progress *prg;
 888         size_t seen;
 889 };
 890
 891 static void test_show_object(struct object *object, const char *name,
 892                              void *data)
 893 {
 894         struct bitmap_test_data *tdata = data;
 895         int bitmap_pos;
 896
 897         bitmap_pos = bitmap_position(object->oid.hash);
 898         if (bitmap_pos < 0)
 899                 die("Object not in bitmap: %s\n", oid_to_hex(&object->oid));
 900
 901         bitmap_set(tdata->base, bitmap_pos);
 902         display_progress(tdata->prg, ++tdata->seen);
 903 }
 904
 905 static void test_show_commit(struct commit *commit, void *data)
 906 {
 907         struct bitmap_test_data *tdata = data;
 908         int bitmap_pos;
 909
 910         bitmap_pos = bitmap_position(commit->object.oid.hash);
 911         if (bitmap_pos < 0)
 912                 die("Object not in bitmap: %s\n", oid_to_hex(&commit->object.oid));
 913
 914         bitmap_set(tdata->base, bitmap_pos);
 915         display_progress(tdata->prg, ++tdata->seen);
 916 }
 917
 918 void test_bitmap_walk(struct rev_info *revs)
 919 {
 920         struct object *root;
 921         struct bitmap *result = NULL;
 922         khiter_t pos;
 923         size_t result_popcnt;
 924         struct bitmap_test_data tdata;
 925
 926         if (prepare_bitmap_git())
 927                 die("failed to load bitmap indexes");
 928
 929         if (revs->pending.nr != 1)
 930                 die("you must specify exactly one commit to test");
 931
 932         fprintf(stderr, "Bitmap v%d test (%d entries loaded)\n",
 933                 bitmap_git.version, bitmap_git.entry_count);
 934
 935         root = revs->pending.objects[0].item;
 936         pos = kh_get_sha1(bitmap_git.bitmaps, root->oid.hash);
 937
 938         if (pos < kh_end(bitmap_git.bitmaps)) {
 939                 struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, pos);
 940                 struct ewah_bitmap *bm = lookup_stored_bitmap(st);
 941
 942                 fprintf(stderr, "Found bitmap for %s. %d bits / %08x checksum\n",
 943                         oid_to_hex(&root->oid), (int)bm->bit_size, ewah_checksum(bm));
 944
 945                 result = ewah_to_bitmap(bm);
 946         }
 947
 948         if (result == NULL)
 949                 die("Commit %s doesn't have an indexed bitmap", oid_to_hex(&root->oid));
 950
 951         revs->tag_objects = 1;
 952         revs->tree_objects = 1;
 953         revs->blob_objects = 1;
 954
 955         result_popcnt = bitmap_popcount(result);
 956
 957         if (prepare_revision_walk(revs))
 958                 die("revision walk setup failed");
 959
 960         tdata.base = bitmap_new();
 961         tdata.prg = start_progress("Verifying bitmap entries", result_popcnt);
 962         tdata.seen = 0;
 963
 964         traverse_commit_list(revs, &test_show_commit, &test_show_object, &tdata);
 965
 966         stop_progress(&tdata.prg);
 967
 968         if (bitmap_equals(result, tdata.base))
 969                 fprintf(stderr, "OK!\n");
 970         else
 971                 fprintf(stderr, "Mismatch!\n");
 972
 973         bitmap_free(result);
 974 }
 975
 976 static int rebuild_bitmap(uint32_t *reposition,
 977                           struct ewah_bitmap *source,
 978                           struct bitmap *dest)
 979 {
 980         uint32_t pos = 0;
 981         struct ewah_iterator it;
 982         eword_t word;
 983
 984         ewah_iterator_init(&it, source);
 985
 986         while (ewah_iterator_next(&word, &it)) {
 987                 uint32_t offset, bit_pos;
 988
 989                 for (offset = 0; offset < BITS_IN_EWORD; ++offset) {
 990                         if ((word >> offset) == 0)
 991                                 break;
 992
 993                         offset += ewah_bit_ctz64(word >> offset);
 994
 995                         bit_pos = reposition[pos + offset];
 996                         if (bit_pos > 0)
 997                                 bitmap_set(dest, bit_pos - 1);
 998                         else /* can't reuse, we don't have the object */
 999                                 return -1;
1000                 }
1001
1002                 pos += BITS_IN_EWORD;
1003         }
1004         return 0;
1005 }
1006
1007 int rebuild_existing_bitmaps(struct packing_data *mapping,
1008                              khash_sha1 *reused_bitmaps,
1009                              int show_progress)
1010 {
1011         uint32_t i, num_objects;
1012         uint32_t *reposition;
1013         struct bitmap *rebuild;
1014         struct stored_bitmap *stored;
1015         struct progress *progress = NULL;
1016
1017         khiter_t hash_pos;
1018         int hash_ret;
1019
1020         if (prepare_bitmap_git() < 0)
1021                 return -1;
1022
1023         num_objects = bitmap_git.pack->num_objects;
1024         reposition = xcalloc(num_objects, sizeof(uint32_t));
1025
1026         for (i = 0; i < num_objects; ++i) {
1027                 const unsigned char *sha1;
1028                 struct revindex_entry *entry;
1029                 struct object_entry *oe;
1030
1031                 entry = &bitmap_git.pack->revindex[i];
1032                 sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
1033                 oe = packlist_find(mapping, sha1, NULL);
1034
1035                 if (oe)
1036                         reposition[i] = oe_in_pack_pos(mapping, oe) + 1;
1037         }
1038
1039         rebuild = bitmap_new();
1040         i = 0;
1041
1042         if (show_progress)
1043                 progress = start_progress("Reusing bitmaps", 0);
1044
1045         kh_foreach_value(bitmap_git.bitmaps, stored, {
1046                 if (stored->flags & BITMAP_FLAG_REUSE) {
1047                         if (!rebuild_bitmap(reposition,
1048                                             lookup_stored_bitmap(stored),
1049                                             rebuild)) {
1050                                 hash_pos = kh_put_sha1(reused_bitmaps,
1051                                                        stored->sha1,
1052                                                        &hash_ret);
1053                                 kh_value(reused_bitmaps, hash_pos) =
1054                                         bitmap_to_ewah(rebuild);
1055                         }
1056                         bitmap_reset(rebuild);
1057                         display_progress(progress, ++i);
1058                 }
1059         });
1060
1061         stop_progress(&progress);
1062
1063         free(reposition);
1064         bitmap_free(rebuild);
1065         return 0;
1066 }