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
  13 /*
  14  * An entry on the bitmap index, representing the bitmap for a given
  15  * commit.
  16  */
  17 struct stored_bitmap {
  18         unsigned char sha1[20];
  19         struct ewah_bitmap *root;
  20         struct stored_bitmap *xor;
  21         int flags;
  22 };
  23
  24 /*
  25  * The currently active bitmap index. By design, repositories only have
  26  * a single bitmap index available (the index for the biggest packfile in
  27  * the repository), since bitmap indexes need full closure.
  28  *
  29  * If there is more than one bitmap index available (e.g. because of alternates),
  30  * the active bitmap index is the largest one.
  31  */
  32 static struct bitmap_index {
  33         /* Packfile to which this bitmap index belongs to */
  34         struct packed_git *pack;
  35
  36         /*
  37          * Mark the first `reuse_objects` in the packfile as reused:
  38          * they will be sent as-is without using them for repacking
  39          * calculations
  40          */
  41         uint32_t reuse_objects;
  42
  43         /* mmapped buffer of the whole bitmap index */
  44         unsigned char *map;
  45         size_t map_size; /* size of the mmaped buffer */
  46         size_t map_pos; /* current position when loading the index */
  47
  48         /*
  49          * Type indexes.
  50          *
  51          * Each bitmap marks which objects in the packfile  are of the given
  52          * type. This provides type information when yielding the objects from
  53          * the packfile during a walk, which allows for better delta bases.
  54          */
  55         struct ewah_bitmap *commits;
  56         struct ewah_bitmap *trees;
  57         struct ewah_bitmap *blobs;
  58         struct ewah_bitmap *tags;
  59
  60         /* Map from SHA1 -> `stored_bitmap` for all the bitmapped commits */
  61         khash_sha1 *bitmaps;
  62
  63         /* Number of bitmapped commits */
  64         uint32_t entry_count;
  65
  66         /* Name-hash cache (or NULL if not present). */
  67         uint32_t *hashes;
  68
  69         /*
  70          * Extended index.
  71          *
  72          * When trying to perform bitmap operations with objects that are not
  73          * packed in `pack`, these objects are added to this "fake index" and
  74          * are assumed to appear at the end of the packfile for all operations
  75          */
  76         struct eindex {
  77                 struct object **objects;
  78                 uint32_t *hashes;
  79                 uint32_t count, alloc;
  80                 khash_sha1_pos *positions;
  81         } ext_index;
  82
  83         /* Bitmap result of the last performed walk */
  84         struct bitmap *result;
  85
  86         /* Version of the bitmap index */
  87         unsigned int version;
  88
  89         unsigned loaded : 1;
  90
  91 } bitmap_git;
  92
  93 static struct ewah_bitmap *lookup_stored_bitmap(struct stored_bitmap *st)
  94 {
  95         struct ewah_bitmap *parent;
  96         struct ewah_bitmap *composed;
  97
  98         if (st->xor == NULL)
  99                 return st->root;
 100
 101         composed = ewah_pool_new();
 102         parent = lookup_stored_bitmap(st->xor);
 103         ewah_xor(st->root, parent, composed);
 104
 105         ewah_pool_free(st->root);
 106         st->root = composed;
 107         st->xor = NULL;
 108
 109         return composed;
 110 }
 111
 112 /*
 113  * Read a bitmap from the current read position on the mmaped
 114  * index, and increase the read position accordingly
 115  */
 116 static struct ewah_bitmap *read_bitmap_1(struct bitmap_index *index)
 117 {
 118         struct ewah_bitmap *b = ewah_pool_new();
 119
 120         int bitmap_size = ewah_read_mmap(b,
 121                 index->map + index->map_pos,
 122                 index->map_size - index->map_pos);
 123
 124         if (bitmap_size < 0) {
 125                 error("Failed to load bitmap index (corrupted?)");
 126                 ewah_pool_free(b);
 127                 return NULL;
 128         }
 129
 130         index->map_pos += bitmap_size;
 131         return b;
 132 }
 133
 134 static int load_bitmap_header(struct bitmap_index *index)
 135 {
 136         struct bitmap_disk_header *header = (void *)index->map;
 137
 138         if (index->map_size < sizeof(*header) + 20)
 139                 return error("Corrupted bitmap index (missing header data)");
 140
 141         if (memcmp(header->magic, BITMAP_IDX_SIGNATURE, sizeof(BITMAP_IDX_SIGNATURE)) != 0)
 142                 return error("Corrupted bitmap index file (wrong header)");
 143
 144         index->version = ntohs(header->version);
 145         if (index->version != 1)
 146                 return error("Unsupported version for bitmap index file (%d)", index->version);
 147
 148         /* Parse known bitmap format options */
 149         {
 150                 uint32_t flags = ntohs(header->options);
 151
 152                 if ((flags & BITMAP_OPT_FULL_DAG) == 0)
 153                         return error("Unsupported options for bitmap index file "
 154                                 "(Git requires BITMAP_OPT_FULL_DAG)");
 155
 156                 if (flags & BITMAP_OPT_HASH_CACHE) {
 157                         unsigned char *end = index->map + index->map_size - 20;
 158                         index->hashes = ((uint32_t *)end) - index->pack->num_objects;
 159                 }
 160         }
 161
 162         index->entry_count = ntohl(header->entry_count);
 163         index->map_pos += sizeof(*header);
 164         return 0;
 165 }
 166
 167 static struct stored_bitmap *store_bitmap(struct bitmap_index *index,
 168                                           struct ewah_bitmap *root,
 169                                           const unsigned char *sha1,
 170                                           struct stored_bitmap *xor_with,
 171                                           int flags)
 172 {
 173         struct stored_bitmap *stored;
 174         khiter_t hash_pos;
 175         int ret;
 176
 177         stored = xmalloc(sizeof(struct stored_bitmap));
 178         stored->root = root;
 179         stored->xor = xor_with;
 180         stored->flags = flags;
 181         hashcpy(stored->sha1, sha1);
 182
 183         hash_pos = kh_put_sha1(index->bitmaps, stored->sha1, &ret);
 184
 185         /* a 0 return code means the insertion succeeded with no changes,
 186          * because the SHA1 already existed on the map. this is bad, there
 187          * shouldn't be duplicated commits in the index */
 188         if (ret == 0) {
 189                 error("Duplicate entry in bitmap index: %s", sha1_to_hex(sha1));
 190                 return NULL;
 191         }
 192
 193         kh_value(index->bitmaps, hash_pos) = stored;
 194         return stored;
 195 }
 196
 197 static inline uint32_t read_be32(const unsigned char *buffer, size_t *pos)
 198 {
 199         uint32_t result = get_be32(buffer + *pos);
 200         (*pos) += sizeof(result);
 201         return result;
 202 }
 203
 204 static inline uint8_t read_u8(const unsigned char *buffer, size_t *pos)
 205 {
 206         return buffer[(*pos)++];
 207 }
 208
 209 #define MAX_XOR_OFFSET 160
 210
 211 static int load_bitmap_entries_v1(struct bitmap_index *index)
 212 {
 213         uint32_t i;
 214         struct stored_bitmap *recent_bitmaps[MAX_XOR_OFFSET] = { NULL };
 215
 216         for (i = 0; i < index->entry_count; ++i) {
 217                 int xor_offset, flags;
 218                 struct ewah_bitmap *bitmap = NULL;
 219                 struct stored_bitmap *xor_bitmap = NULL;
 220                 uint32_t commit_idx_pos;
 221                 const unsigned char *sha1;
 222
 223                 commit_idx_pos = read_be32(index->map, &index->map_pos);
 224                 xor_offset = read_u8(index->map, &index->map_pos);
 225                 flags = read_u8(index->map, &index->map_pos);
 226
 227                 sha1 = nth_packed_object_sha1(index->pack, commit_idx_pos);
 228
 229                 bitmap = read_bitmap_1(index);
 230                 if (!bitmap)
 231                         return -1;
 232
 233                 if (xor_offset > MAX_XOR_OFFSET || xor_offset > i)
 234                         return error("Corrupted bitmap pack index");
 235
 236                 if (xor_offset > 0) {
 237                         xor_bitmap = recent_bitmaps[(i - xor_offset) % MAX_XOR_OFFSET];
 238
 239                         if (xor_bitmap == NULL)
 240                                 return error("Invalid XOR offset in bitmap pack index");
 241                 }
 242
 243                 recent_bitmaps[i % MAX_XOR_OFFSET] = store_bitmap(
 244                         index, bitmap, sha1, xor_bitmap, flags);
 245         }
 246
 247         return 0;
 248 }
 249
 250 static char *pack_bitmap_filename(struct packed_git *p)
 251 {
 252         size_t len;
 253
 254         if (!strip_suffix(p->pack_name, ".pack", &len))
 255                 die("BUG: pack_name does not end in .pack");
 256         return xstrfmt("%.*s.bitmap", (int)len, p->pack_name);
 257 }
 258
 259 static int open_pack_bitmap_1(struct packed_git *packfile)
 260 {
 261         int fd;
 262         struct stat st;
 263         char *idx_name;
 264
 265         if (open_pack_index(packfile))
 266                 return -1;
 267
 268         idx_name = pack_bitmap_filename(packfile);
 269         fd = git_open_noatime(idx_name);
 270         free(idx_name);
 271
 272         if (fd < 0)
 273                 return -1;
 274
 275         if (fstat(fd, &st)) {
 276                 close(fd);
 277                 return -1;
 278         }
 279
 280         if (bitmap_git.pack) {
 281                 warning("ignoring extra bitmap file: %s", packfile->pack_name);
 282                 close(fd);
 283                 return -1;
 284         }
 285
 286         bitmap_git.pack = packfile;
 287         bitmap_git.map_size = xsize_t(st.st_size);
 288         bitmap_git.map = xmmap(NULL, bitmap_git.map_size, PROT_READ, MAP_PRIVATE, fd, 0);
 289         bitmap_git.map_pos = 0;
 290         close(fd);
 291
 292         if (load_bitmap_header(&bitmap_git) < 0) {
 293                 munmap(bitmap_git.map, bitmap_git.map_size);
 294                 bitmap_git.map = NULL;
 295                 bitmap_git.map_size = 0;
 296                 return -1;
 297         }
 298
 299         return 0;
 300 }
 301
 302 static int load_pack_bitmap(void)
 303 {
 304         assert(bitmap_git.map && !bitmap_git.loaded);
 305
 306         bitmap_git.bitmaps = kh_init_sha1();
 307         bitmap_git.ext_index.positions = kh_init_sha1_pos();
 308         load_pack_revindex(bitmap_git.pack);
 309
 310         if (!(bitmap_git.commits = read_bitmap_1(&bitmap_git)) ||
 311                 !(bitmap_git.trees = read_bitmap_1(&bitmap_git)) ||
 312                 !(bitmap_git.blobs = read_bitmap_1(&bitmap_git)) ||
 313                 !(bitmap_git.tags = read_bitmap_1(&bitmap_git)))
 314                 goto failed;
 315
 316         if (load_bitmap_entries_v1(&bitmap_git) < 0)
 317                 goto failed;
 318
 319         bitmap_git.loaded = 1;
 320         return 0;
 321
 322 failed:
 323         munmap(bitmap_git.map, bitmap_git.map_size);
 324         bitmap_git.map = NULL;
 325         bitmap_git.map_size = 0;
 326         return -1;
 327 }
 328
 329 static int open_pack_bitmap(void)
 330 {
 331         struct packed_git *p;
 332         int ret = -1;
 333
 334         assert(!bitmap_git.map && !bitmap_git.loaded);
 335
 336         prepare_packed_git();
 337         for (p = packed_git; p; p = p->next) {
 338                 if (open_pack_bitmap_1(p) == 0)
 339                         ret = 0;
 340         }
 341
 342         return ret;
 343 }
 344
 345 int prepare_bitmap_git(void)
 346 {
 347         if (bitmap_git.loaded)
 348                 return 0;
 349
 350         if (!open_pack_bitmap())
 351                 return load_pack_bitmap();
 352
 353         return -1;
 354 }
 355
 356 struct include_data {
 357         struct bitmap *base;
 358         struct bitmap *seen;
 359 };
 360
 361 static inline int bitmap_position_extended(const unsigned char *sha1)
 362 {
 363         khash_sha1_pos *positions = bitmap_git.ext_index.positions;
 364         khiter_t pos = kh_get_sha1_pos(positions, sha1);
 365
 366         if (pos < kh_end(positions)) {
 367                 int bitmap_pos = kh_value(positions, pos);
 368                 return bitmap_pos + bitmap_git.pack->num_objects;
 369         }
 370
 371         return -1;
 372 }
 373
 374 static inline int bitmap_position_packfile(const unsigned char *sha1)
 375 {
 376         off_t offset = find_pack_entry_one(sha1, bitmap_git.pack);
 377         if (!offset)
 378                 return -1;
 379
 380         return find_revindex_position(bitmap_git.pack, offset);
 381 }
 382
 383 static int bitmap_position(const unsigned char *sha1)
 384 {
 385         int pos = bitmap_position_packfile(sha1);
 386         return (pos >= 0) ? pos : bitmap_position_extended(sha1);
 387 }
 388
 389 static int ext_index_add_object(struct object *object, const char *name)
 390 {
 391         struct eindex *eindex = &bitmap_git.ext_index;
 392
 393         khiter_t hash_pos;
 394         int hash_ret;
 395         int bitmap_pos;
 396
 397         hash_pos = kh_put_sha1_pos(eindex->positions, object->oid.hash, &hash_ret);
 398         if (hash_ret > 0) {
 399                 if (eindex->count >= eindex->alloc) {
 400                         eindex->alloc = (eindex->alloc + 16) * 3 / 2;
 401                         REALLOC_ARRAY(eindex->objects, eindex->alloc);
 402                         REALLOC_ARRAY(eindex->hashes, eindex->alloc);
 403                 }
 404
 405                 bitmap_pos = eindex->count;
 406                 eindex->objects[eindex->count] = object;
 407                 eindex->hashes[eindex->count] = pack_name_hash(name);
 408                 kh_value(eindex->positions, hash_pos) = bitmap_pos;
 409                 eindex->count++;
 410         } else {
 411                 bitmap_pos = kh_value(eindex->positions, hash_pos);
 412         }
 413
 414         return bitmap_pos + bitmap_git.pack->num_objects;
 415 }
 416
 417 static void show_object(struct object *object, const struct name_path *path,
 418                         const char *last, void *data)
 419 {
 420         struct bitmap *base = data;
 421         int bitmap_pos;
 422
 423         bitmap_pos = bitmap_position(object->oid.hash);
 424
 425         if (bitmap_pos < 0) {
 426                 char *name = path_name(path, last);
 427                 bitmap_pos = ext_index_add_object(object, name);
 428                 free(name);
 429         }
 430
 431         bitmap_set(base, bitmap_pos);
 432 }
 433
 434 static void show_commit(struct commit *commit, void *data)
 435 {
 436 }
 437
 438 static int add_to_include_set(struct include_data *data,
 439                               const unsigned char *sha1,
 440                               int bitmap_pos)
 441 {
 442         khiter_t hash_pos;
 443
 444         if (data->seen && bitmap_get(data->seen, bitmap_pos))
 445                 return 0;
 446
 447         if (bitmap_get(data->base, bitmap_pos))
 448                 return 0;
 449
 450         hash_pos = kh_get_sha1(bitmap_git.bitmaps, sha1);
 451         if (hash_pos < kh_end(bitmap_git.bitmaps)) {
 452                 struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, hash_pos);
 453                 bitmap_or_ewah(data->base, lookup_stored_bitmap(st));
 454                 return 0;
 455         }
 456
 457         bitmap_set(data->base, bitmap_pos);
 458         return 1;
 459 }
 460
 461 static int should_include(struct commit *commit, void *_data)
 462 {
 463         struct include_data *data = _data;
 464         int bitmap_pos;
 465
 466         bitmap_pos = bitmap_position(commit->object.oid.hash);
 467         if (bitmap_pos < 0)
 468                 bitmap_pos = ext_index_add_object((struct object *)commit, NULL);
 469
 470         if (!add_to_include_set(data, commit->object.oid.hash, bitmap_pos)) {
 471                 struct commit_list *parent = commit->parents;
 472
 473                 while (parent) {
 474                         parent->item->object.flags |= SEEN;
 475                         parent = parent->next;
 476                 }
 477
 478                 return 0;
 479         }
 480
 481         return 1;
 482 }
 483
 484 static struct bitmap *find_objects(struct rev_info *revs,
 485                                    struct object_list *roots,
 486                                    struct bitmap *seen)
 487 {
 488         struct bitmap *base = NULL;
 489         int needs_walk = 0;
 490
 491         struct object_list *not_mapped = NULL;
 492
 493         /*
 494          * Go through all the roots for the walk. The ones that have bitmaps
 495          * on the bitmap index will be `or`ed together to form an initial
 496          * global reachability analysis.
 497          *
 498          * The ones without bitmaps in the index will be stored in the
 499          * `not_mapped_list` for further processing.
 500          */
 501         while (roots) {
 502                 struct object *object = roots->item;
 503                 roots = roots->next;
 504
 505                 if (object->type == OBJ_COMMIT) {
 506                         khiter_t pos = kh_get_sha1(bitmap_git.bitmaps, object->oid.hash);
 507
 508                         if (pos < kh_end(bitmap_git.bitmaps)) {
 509                                 struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, pos);
 510                                 struct ewah_bitmap *or_with = lookup_stored_bitmap(st);
 511
 512                                 if (base == NULL)
 513                                         base = ewah_to_bitmap(or_with);
 514                                 else
 515                                         bitmap_or_ewah(base, or_with);
 516
 517                                 object->flags |= SEEN;
 518                                 continue;
 519                         }
 520                 }
 521
 522                 object_list_insert(object, &not_mapped);
 523         }
 524
 525         /*
 526          * Best case scenario: We found bitmaps for all the roots,
 527          * so the resulting `or` bitmap has the full reachability analysis
 528          */
 529         if (not_mapped == NULL)
 530                 return base;
 531
 532         roots = not_mapped;
 533
 534         /*
 535          * Let's iterate through all the roots that don't have bitmaps to
 536          * check if we can determine them to be reachable from the existing
 537          * global bitmap.
 538          *
 539          * If we cannot find them in the existing global bitmap, we'll need
 540          * to push them to an actual walk and run it until we can confirm
 541          * they are reachable
 542          */
 543         while (roots) {
 544                 struct object *object = roots->item;
 545                 int pos;
 546
 547                 roots = roots->next;
 548                 pos = bitmap_position(object->oid.hash);
 549
 550                 if (pos < 0 || base == NULL || !bitmap_get(base, pos)) {
 551                         object->flags &= ~UNINTERESTING;
 552                         add_pending_object(revs, object, "");
 553                         needs_walk = 1;
 554                 } else {
 555                         object->flags |= SEEN;
 556                 }
 557         }
 558
 559         if (needs_walk) {
 560                 struct include_data incdata;
 561
 562                 if (base == NULL)
 563                         base = bitmap_new();
 564
 565                 incdata.base = base;
 566                 incdata.seen = seen;
 567
 568                 revs->include_check = should_include;
 569                 revs->include_check_data = &incdata;
 570
 571                 if (prepare_revision_walk(revs))
 572                         die("revision walk setup failed");
 573
 574                 traverse_commit_list(revs, show_commit, show_object, base);
 575         }
 576
 577         return base;
 578 }
 579
 580 static void show_extended_objects(struct bitmap *objects,
 581                                   show_reachable_fn show_reach)
 582 {
 583         struct eindex *eindex = &bitmap_git.ext_index;
 584         uint32_t i;
 585
 586         for (i = 0; i < eindex->count; ++i) {
 587                 struct object *obj;
 588
 589                 if (!bitmap_get(objects, bitmap_git.pack->num_objects + i))
 590                         continue;
 591
 592                 obj = eindex->objects[i];
 593                 show_reach(obj->oid.hash, obj->type, 0, eindex->hashes[i], NULL, 0);
 594         }
 595 }
 596
 597 static void show_objects_for_type(
 598         struct bitmap *objects,
 599         struct ewah_bitmap *type_filter,
 600         enum object_type object_type,
 601         show_reachable_fn show_reach)
 602 {
 603         size_t pos = 0, i = 0;
 604         uint32_t offset;
 605
 606         struct ewah_iterator it;
 607         eword_t filter;
 608
 609         if (bitmap_git.reuse_objects == bitmap_git.pack->num_objects)
 610                 return;
 611
 612         ewah_iterator_init(&it, type_filter);
 613
 614         while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) {
 615                 eword_t word = objects->words[i] & filter;
 616
 617                 for (offset = 0; offset < BITS_IN_EWORD; ++offset) {
 618                         const unsigned char *sha1;
 619                         struct revindex_entry *entry;
 620                         uint32_t hash = 0;
 621
 622                         if ((word >> offset) == 0)
 623                                 break;
 624
 625                         offset += ewah_bit_ctz64(word >> offset);
 626
 627                         if (pos + offset < bitmap_git.reuse_objects)
 628                                 continue;
 629
 630                         entry = &bitmap_git.pack->revindex[pos + offset];
 631                         sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
 632
 633                         if (bitmap_git.hashes)
 634                                 hash = ntohl(bitmap_git.hashes[entry->nr]);
 635
 636                         show_reach(sha1, object_type, 0, hash, bitmap_git.pack, entry->offset);
 637                 }
 638
 639                 pos += BITS_IN_EWORD;
 640                 i++;
 641         }
 642 }
 643
 644 static int in_bitmapped_pack(struct object_list *roots)
 645 {
 646         while (roots) {
 647                 struct object *object = roots->item;
 648                 roots = roots->next;
 649
 650                 if (find_pack_entry_one(object->oid.hash, bitmap_git.pack) > 0)
 651                         return 1;
 652         }
 653
 654         return 0;
 655 }
 656
 657 int prepare_bitmap_walk(struct rev_info *revs)
 658 {
 659         unsigned int i;
 660         unsigned int pending_nr = revs->pending.nr;
 661         struct object_array_entry *pending_e = revs->pending.objects;
 662
 663         struct object_list *wants = NULL;
 664         struct object_list *haves = NULL;
 665
 666         struct bitmap *wants_bitmap = NULL;
 667         struct bitmap *haves_bitmap = NULL;
 668
 669         if (!bitmap_git.loaded) {
 670                 /* try to open a bitmapped pack, but don't parse it yet
 671                  * because we may not need to use it */
 672                 if (open_pack_bitmap() < 0)
 673                         return -1;
 674         }
 675
 676         for (i = 0; i < pending_nr; ++i) {
 677                 struct object *object = pending_e[i].item;
 678
 679                 if (object->type == OBJ_NONE)
 680                         parse_object_or_die(object->oid.hash, NULL);
 681
 682                 while (object->type == OBJ_TAG) {
 683                         struct tag *tag = (struct tag *) object;
 684
 685                         if (object->flags & UNINTERESTING)
 686                                 object_list_insert(object, &haves);
 687                         else
 688                                 object_list_insert(object, &wants);
 689
 690                         if (!tag->tagged)
 691                                 die("bad tag");
 692                         object = parse_object_or_die(tag->tagged->oid.hash, NULL);
 693                 }
 694
 695                 if (object->flags & UNINTERESTING)
 696                         object_list_insert(object, &haves);
 697                 else
 698                         object_list_insert(object, &wants);
 699         }
 700
 701         /*
 702          * if we have a HAVES list, but none of those haves is contained
 703          * in the packfile that has a bitmap, we don't have anything to
 704          * optimize here
 705          */
 706         if (haves && !in_bitmapped_pack(haves))
 707                 return -1;
 708
 709         /* if we don't want anything, we're done here */
 710         if (!wants)
 711                 return -1;
 712
 713         /*
 714          * now we're going to use bitmaps, so load the actual bitmap entries
 715          * from disk. this is the point of no return; after this the rev_list
 716          * becomes invalidated and we must perform the revwalk through bitmaps
 717          */
 718         if (!bitmap_git.loaded && load_pack_bitmap() < 0)
 719                 return -1;
 720
 721         revs->pending.nr = 0;
 722         revs->pending.alloc = 0;
 723         revs->pending.objects = NULL;
 724
 725         if (haves) {
 726                 revs->ignore_missing_links = 1;
 727                 haves_bitmap = find_objects(revs, haves, NULL);
 728                 reset_revision_walk();
 729                 revs->ignore_missing_links = 0;
 730
 731                 if (haves_bitmap == NULL)
 732                         die("BUG: failed to perform bitmap walk");
 733         }
 734
 735         wants_bitmap = find_objects(revs, wants, haves_bitmap);
 736
 737         if (!wants_bitmap)
 738                 die("BUG: failed to perform bitmap walk");
 739
 740         if (haves_bitmap)
 741                 bitmap_and_not(wants_bitmap, haves_bitmap);
 742
 743         bitmap_git.result = wants_bitmap;
 744
 745         bitmap_free(haves_bitmap);
 746         return 0;
 747 }
 748
 749 int reuse_partial_packfile_from_bitmap(struct packed_git **packfile,
 750                                        uint32_t *entries,
 751                                        off_t *up_to)
 752 {
 753         /*
 754          * Reuse the packfile content if we need more than
 755          * 90% of its objects
 756          */
 757         static const double REUSE_PERCENT = 0.9;
 758
 759         struct bitmap *result = bitmap_git.result;
 760         uint32_t reuse_threshold;
 761         uint32_t i, reuse_objects = 0;
 762
 763         assert(result);
 764
 765         for (i = 0; i < result->word_alloc; ++i) {
 766                 if (result->words[i] != (eword_t)~0) {
 767                         reuse_objects += ewah_bit_ctz64(~result->words[i]);
 768                         break;
 769                 }
 770
 771                 reuse_objects += BITS_IN_EWORD;
 772         }
 773
 774 #ifdef GIT_BITMAP_DEBUG
 775         {
 776                 const unsigned char *sha1;
 777                 struct revindex_entry *entry;
 778
 779                 entry = &bitmap_git.reverse_index->revindex[reuse_objects];
 780                 sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
 781
 782                 fprintf(stderr, "Failed to reuse at %d (%016llx)\n",
 783                         reuse_objects, result->words[i]);
 784                 fprintf(stderr, " %s\n", sha1_to_hex(sha1));
 785         }
 786 #endif
 787
 788         if (!reuse_objects)
 789                 return -1;
 790
 791         if (reuse_objects >= bitmap_git.pack->num_objects) {
 792                 bitmap_git.reuse_objects = *entries = bitmap_git.pack->num_objects;
 793                 *up_to = -1; /* reuse the full pack */
 794                 *packfile = bitmap_git.pack;
 795                 return 0;
 796         }
 797
 798         reuse_threshold = bitmap_popcount(bitmap_git.result) * REUSE_PERCENT;
 799
 800         if (reuse_objects < reuse_threshold)
 801                 return -1;
 802
 803         bitmap_git.reuse_objects = *entries = reuse_objects;
 804         *up_to = bitmap_git.pack->revindex[reuse_objects].offset;
 805         *packfile = bitmap_git.pack;
 806
 807         return 0;
 808 }
 809
 810 void traverse_bitmap_commit_list(show_reachable_fn show_reachable)
 811 {
 812         assert(bitmap_git.result);
 813
 814         show_objects_for_type(bitmap_git.result, bitmap_git.commits,
 815                 OBJ_COMMIT, show_reachable);
 816         show_objects_for_type(bitmap_git.result, bitmap_git.trees,
 817                 OBJ_TREE, show_reachable);
 818         show_objects_for_type(bitmap_git.result, bitmap_git.blobs,
 819                 OBJ_BLOB, show_reachable);
 820         show_objects_for_type(bitmap_git.result, bitmap_git.tags,
 821                 OBJ_TAG, show_reachable);
 822
 823         show_extended_objects(bitmap_git.result, show_reachable);
 824
 825         bitmap_free(bitmap_git.result);
 826         bitmap_git.result = NULL;
 827 }
 828
 829 static uint32_t count_object_type(struct bitmap *objects,
 830                                   enum object_type type)
 831 {
 832         struct eindex *eindex = &bitmap_git.ext_index;
 833
 834         uint32_t i = 0, count = 0;
 835         struct ewah_iterator it;
 836         eword_t filter;
 837
 838         switch (type) {
 839         case OBJ_COMMIT:
 840                 ewah_iterator_init(&it, bitmap_git.commits);
 841                 break;
 842
 843         case OBJ_TREE:
 844                 ewah_iterator_init(&it, bitmap_git.trees);
 845                 break;
 846
 847         case OBJ_BLOB:
 848                 ewah_iterator_init(&it, bitmap_git.blobs);
 849                 break;
 850
 851         case OBJ_TAG:
 852                 ewah_iterator_init(&it, bitmap_git.tags);
 853                 break;
 854
 855         default:
 856                 return 0;
 857         }
 858
 859         while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) {
 860                 eword_t word = objects->words[i++] & filter;
 861                 count += ewah_bit_popcount64(word);
 862         }
 863
 864         for (i = 0; i < eindex->count; ++i) {
 865                 if (eindex->objects[i]->type == type &&
 866                         bitmap_get(objects, bitmap_git.pack->num_objects + i))
 867                         count++;
 868         }
 869
 870         return count;
 871 }
 872
 873 void count_bitmap_commit_list(uint32_t *commits, uint32_t *trees,
 874                               uint32_t *blobs, uint32_t *tags)
 875 {
 876         assert(bitmap_git.result);
 877
 878         if (commits)
 879                 *commits = count_object_type(bitmap_git.result, OBJ_COMMIT);
 880
 881         if (trees)
 882                 *trees = count_object_type(bitmap_git.result, OBJ_TREE);
 883
 884         if (blobs)
 885                 *blobs = count_object_type(bitmap_git.result, OBJ_BLOB);
 886
 887         if (tags)
 888                 *tags = count_object_type(bitmap_git.result, OBJ_TAG);
 889 }
 890
 891 struct bitmap_test_data {
 892         struct bitmap *base;
 893         struct progress *prg;
 894         size_t seen;
 895 };
 896
 897 static void test_show_object(struct object *object,
 898                              const struct name_path *path,
 899                              const char *last, void *data)
 900 {
 901         struct bitmap_test_data *tdata = data;
 902         int bitmap_pos;
 903
 904         bitmap_pos = bitmap_position(object->oid.hash);
 905         if (bitmap_pos < 0)
 906                 die("Object not in bitmap: %s\n", oid_to_hex(&object->oid));
 907
 908         bitmap_set(tdata->base, bitmap_pos);
 909         display_progress(tdata->prg, ++tdata->seen);
 910 }
 911
 912 static void test_show_commit(struct commit *commit, void *data)
 913 {
 914         struct bitmap_test_data *tdata = data;
 915         int bitmap_pos;
 916
 917         bitmap_pos = bitmap_position(commit->object.oid.hash);
 918         if (bitmap_pos < 0)
 919                 die("Object not in bitmap: %s\n", oid_to_hex(&commit->object.oid));
 920
 921         bitmap_set(tdata->base, bitmap_pos);
 922         display_progress(tdata->prg, ++tdata->seen);
 923 }
 924
 925 void test_bitmap_walk(struct rev_info *revs)
 926 {
 927         struct object *root;
 928         struct bitmap *result = NULL;
 929         khiter_t pos;
 930         size_t result_popcnt;
 931         struct bitmap_test_data tdata;
 932
 933         if (prepare_bitmap_git())
 934                 die("failed to load bitmap indexes");
 935
 936         if (revs->pending.nr != 1)
 937                 die("you must specify exactly one commit to test");
 938
 939         fprintf(stderr, "Bitmap v%d test (%d entries loaded)\n",
 940                 bitmap_git.version, bitmap_git.entry_count);
 941
 942         root = revs->pending.objects[0].item;
 943         pos = kh_get_sha1(bitmap_git.bitmaps, root->oid.hash);
 944
 945         if (pos < kh_end(bitmap_git.bitmaps)) {
 946                 struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, pos);
 947                 struct ewah_bitmap *bm = lookup_stored_bitmap(st);
 948
 949                 fprintf(stderr, "Found bitmap for %s. %d bits / %08x checksum\n",
 950                         oid_to_hex(&root->oid), (int)bm->bit_size, ewah_checksum(bm));
 951
 952                 result = ewah_to_bitmap(bm);
 953         }
 954
 955         if (result == NULL)
 956                 die("Commit %s doesn't have an indexed bitmap", oid_to_hex(&root->oid));
 957
 958         revs->tag_objects = 1;
 959         revs->tree_objects = 1;
 960         revs->blob_objects = 1;
 961
 962         result_popcnt = bitmap_popcount(result);
 963
 964         if (prepare_revision_walk(revs))
 965                 die("revision walk setup failed");
 966
 967         tdata.base = bitmap_new();
 968         tdata.prg = start_progress("Verifying bitmap entries", result_popcnt);
 969         tdata.seen = 0;
 970
 971         traverse_commit_list(revs, &test_show_commit, &test_show_object, &tdata);
 972
 973         stop_progress(&tdata.prg);
 974
 975         if (bitmap_equals(result, tdata.base))
 976                 fprintf(stderr, "OK!\n");
 977         else
 978                 fprintf(stderr, "Mismatch!\n");
 979
 980         bitmap_free(result);
 981 }
 982
 983 static int rebuild_bitmap(uint32_t *reposition,
 984                           struct ewah_bitmap *source,
 985                           struct bitmap *dest)
 986 {
 987         uint32_t pos = 0;
 988         struct ewah_iterator it;
 989         eword_t word;
 990
 991         ewah_iterator_init(&it, source);
 992
 993         while (ewah_iterator_next(&word, &it)) {
 994                 uint32_t offset, bit_pos;
 995
 996                 for (offset = 0; offset < BITS_IN_EWORD; ++offset) {
 997                         if ((word >> offset) == 0)
 998                                 break;
 999
1000                         offset += ewah_bit_ctz64(word >> offset);
1001
1002                         bit_pos = reposition[pos + offset];
1003                         if (bit_pos > 0)
1004                                 bitmap_set(dest, bit_pos - 1);
1005                         else /* can't reuse, we don't have the object */
1006                                 return -1;
1007                 }
1008
1009                 pos += BITS_IN_EWORD;
1010         }
1011         return 0;
1012 }
1013
1014 int rebuild_existing_bitmaps(struct packing_data *mapping,
1015                              khash_sha1 *reused_bitmaps,
1016                              int show_progress)
1017 {
1018         uint32_t i, num_objects;
1019         uint32_t *reposition;
1020         struct bitmap *rebuild;
1021         struct stored_bitmap *stored;
1022         struct progress *progress = NULL;
1023
1024         khiter_t hash_pos;
1025         int hash_ret;
1026
1027         if (prepare_bitmap_git() < 0)
1028                 return -1;
1029
1030         num_objects = bitmap_git.pack->num_objects;
1031         reposition = xcalloc(num_objects, sizeof(uint32_t));
1032
1033         for (i = 0; i < num_objects; ++i) {
1034                 const unsigned char *sha1;
1035                 struct revindex_entry *entry;
1036                 struct object_entry *oe;
1037
1038                 entry = &bitmap_git.pack->revindex[i];
1039                 sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
1040                 oe = packlist_find(mapping, sha1, NULL);
1041
1042                 if (oe)
1043                         reposition[i] = oe->in_pack_pos + 1;
1044         }
1045
1046         rebuild = bitmap_new();
1047         i = 0;
1048
1049         if (show_progress)
1050                 progress = start_progress("Reusing bitmaps", 0);
1051
1052         kh_foreach_value(bitmap_git.bitmaps, stored, {
1053                 if (stored->flags & BITMAP_FLAG_REUSE) {
1054                         if (!rebuild_bitmap(reposition,
1055                                             lookup_stored_bitmap(stored),
1056                                             rebuild)) {
1057                                 hash_pos = kh_put_sha1(reused_bitmaps,
1058                                                        stored->sha1,
1059                                                        &hash_ret);
1060                                 kh_value(reused_bitmaps, hash_pos) =
1061                                         bitmap_to_ewah(rebuild);
1062                         }
1063                         bitmap_reset(rebuild);
1064                         display_progress(progress, ++i);
1065                 }
1066         });
1067
1068         stop_progress(&progress);
1069
1070         free(reposition);
1071         bitmap_free(rebuild);
1072         return 0;
1073 }