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
  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(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 char *name, void *data)
 418 {
 419         struct bitmap *base = data;
 420         int bitmap_pos;
 421
 422         bitmap_pos = bitmap_position(object->oid.hash);
 423
 424         if (bitmap_pos < 0)
 425                 bitmap_pos = ext_index_add_object(object, name);
 426
 427         bitmap_set(base, bitmap_pos);
 428 }
 429
 430 static void show_commit(struct commit *commit, void *data)
 431 {
 432 }
 433
 434 static int add_to_include_set(struct include_data *data,
 435                               const unsigned char *sha1,
 436                               int bitmap_pos)
 437 {
 438         khiter_t hash_pos;
 439
 440         if (data->seen && bitmap_get(data->seen, bitmap_pos))
 441                 return 0;
 442
 443         if (bitmap_get(data->base, bitmap_pos))
 444                 return 0;
 445
 446         hash_pos = kh_get_sha1(bitmap_git.bitmaps, sha1);
 447         if (hash_pos < kh_end(bitmap_git.bitmaps)) {
 448                 struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, hash_pos);
 449                 bitmap_or_ewah(data->base, lookup_stored_bitmap(st));
 450                 return 0;
 451         }
 452
 453         bitmap_set(data->base, bitmap_pos);
 454         return 1;
 455 }
 456
 457 static int should_include(struct commit *commit, void *_data)
 458 {
 459         struct include_data *data = _data;
 460         int bitmap_pos;
 461
 462         bitmap_pos = bitmap_position(commit->object.oid.hash);
 463         if (bitmap_pos < 0)
 464                 bitmap_pos = ext_index_add_object((struct object *)commit, NULL);
 465
 466         if (!add_to_include_set(data, commit->object.oid.hash, bitmap_pos)) {
 467                 struct commit_list *parent = commit->parents;
 468
 469                 while (parent) {
 470                         parent->item->object.flags |= SEEN;
 471                         parent = parent->next;
 472                 }
 473
 474                 return 0;
 475         }
 476
 477         return 1;
 478 }
 479
 480 static struct bitmap *find_objects(struct rev_info *revs,
 481                                    struct object_list *roots,
 482                                    struct bitmap *seen)
 483 {
 484         struct bitmap *base = NULL;
 485         int needs_walk = 0;
 486
 487         struct object_list *not_mapped = NULL;
 488
 489         /*
 490          * Go through all the roots for the walk. The ones that have bitmaps
 491          * on the bitmap index will be `or`ed together to form an initial
 492          * global reachability analysis.
 493          *
 494          * The ones without bitmaps in the index will be stored in the
 495          * `not_mapped_list` for further processing.
 496          */
 497         while (roots) {
 498                 struct object *object = roots->item;
 499                 roots = roots->next;
 500
 501                 if (object->type == OBJ_COMMIT) {
 502                         khiter_t pos = kh_get_sha1(bitmap_git.bitmaps, object->oid.hash);
 503
 504                         if (pos < kh_end(bitmap_git.bitmaps)) {
 505                                 struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, pos);
 506                                 struct ewah_bitmap *or_with = lookup_stored_bitmap(st);
 507
 508                                 if (base == NULL)
 509                                         base = ewah_to_bitmap(or_with);
 510                                 else
 511                                         bitmap_or_ewah(base, or_with);
 512
 513                                 object->flags |= SEEN;
 514                                 continue;
 515                         }
 516                 }
 517
 518                 object_list_insert(object, &not_mapped);
 519         }
 520
 521         /*
 522          * Best case scenario: We found bitmaps for all the roots,
 523          * so the resulting `or` bitmap has the full reachability analysis
 524          */
 525         if (not_mapped == NULL)
 526                 return base;
 527
 528         roots = not_mapped;
 529
 530         /*
 531          * Let's iterate through all the roots that don't have bitmaps to
 532          * check if we can determine them to be reachable from the existing
 533          * global bitmap.
 534          *
 535          * If we cannot find them in the existing global bitmap, we'll need
 536          * to push them to an actual walk and run it until we can confirm
 537          * they are reachable
 538          */
 539         while (roots) {
 540                 struct object *object = roots->item;
 541                 int pos;
 542
 543                 roots = roots->next;
 544                 pos = bitmap_position(object->oid.hash);
 545
 546                 if (pos < 0 || base == NULL || !bitmap_get(base, pos)) {
 547                         object->flags &= ~UNINTERESTING;
 548                         add_pending_object(revs, object, "");
 549                         needs_walk = 1;
 550                 } else {
 551                         object->flags |= SEEN;
 552                 }
 553         }
 554
 555         if (needs_walk) {
 556                 struct include_data incdata;
 557
 558                 if (base == NULL)
 559                         base = bitmap_new();
 560
 561                 incdata.base = base;
 562                 incdata.seen = seen;
 563
 564                 revs->include_check = should_include;
 565                 revs->include_check_data = &incdata;
 566
 567                 if (prepare_revision_walk(revs))
 568                         die("revision walk setup failed");
 569
 570                 traverse_commit_list(revs, show_commit, show_object, base);
 571         }
 572
 573         return base;
 574 }
 575
 576 static void show_extended_objects(struct bitmap *objects,
 577                                   show_reachable_fn show_reach)
 578 {
 579         struct eindex *eindex = &bitmap_git.ext_index;
 580         uint32_t i;
 581
 582         for (i = 0; i < eindex->count; ++i) {
 583                 struct object *obj;
 584
 585                 if (!bitmap_get(objects, bitmap_git.pack->num_objects + i))
 586                         continue;
 587
 588                 obj = eindex->objects[i];
 589                 show_reach(obj->oid.hash, obj->type, 0, eindex->hashes[i], NULL, 0);
 590         }
 591 }
 592
 593 static void show_objects_for_type(
 594         struct bitmap *objects,
 595         struct ewah_bitmap *type_filter,
 596         enum object_type object_type,
 597         show_reachable_fn show_reach)
 598 {
 599         size_t pos = 0, i = 0;
 600         uint32_t offset;
 601
 602         struct ewah_iterator it;
 603         eword_t filter;
 604
 605         if (bitmap_git.reuse_objects == bitmap_git.pack->num_objects)
 606                 return;
 607
 608         ewah_iterator_init(&it, type_filter);
 609
 610         while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) {
 611                 eword_t word = objects->words[i] & filter;
 612
 613                 for (offset = 0; offset < BITS_IN_EWORD; ++offset) {
 614                         const unsigned char *sha1;
 615                         struct revindex_entry *entry;
 616                         uint32_t hash = 0;
 617
 618                         if ((word >> offset) == 0)
 619                                 break;
 620
 621                         offset += ewah_bit_ctz64(word >> offset);
 622
 623                         if (pos + offset < bitmap_git.reuse_objects)
 624                                 continue;
 625
 626                         entry = &bitmap_git.pack->revindex[pos + offset];
 627                         sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
 628
 629                         if (bitmap_git.hashes)
 630                                 hash = ntohl(bitmap_git.hashes[entry->nr]);
 631
 632                         show_reach(sha1, object_type, 0, hash, bitmap_git.pack, entry->offset);
 633                 }
 634
 635                 pos += BITS_IN_EWORD;
 636                 i++;
 637         }
 638 }
 639
 640 static int in_bitmapped_pack(struct object_list *roots)
 641 {
 642         while (roots) {
 643                 struct object *object = roots->item;
 644                 roots = roots->next;
 645
 646                 if (find_pack_entry_one(object->oid.hash, bitmap_git.pack) > 0)
 647                         return 1;
 648         }
 649
 650         return 0;
 651 }
 652
 653 int prepare_bitmap_walk(struct rev_info *revs)
 654 {
 655         unsigned int i;
 656         unsigned int pending_nr = revs->pending.nr;
 657         struct object_array_entry *pending_e = revs->pending.objects;
 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 < pending_nr; ++i) {
 673                 struct object *object = pending_e[i].item;
 674
 675                 if (object->type == OBJ_NONE)
 676                         parse_object_or_die(object->oid.hash, 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.hash, 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         revs->pending.nr = 0;
 718         revs->pending.alloc = 0;
 719         revs->pending.objects = NULL;
 720
 721         if (haves) {
 722                 revs->ignore_missing_links = 1;
 723                 haves_bitmap = find_objects(revs, haves, NULL);
 724                 reset_revision_walk();
 725                 revs->ignore_missing_links = 0;
 726
 727                 if (haves_bitmap == NULL)
 728                         die("BUG: failed to perform bitmap walk");
 729         }
 730
 731         wants_bitmap = find_objects(revs, wants, haves_bitmap);
 732
 733         if (!wants_bitmap)
 734                 die("BUG: failed to perform bitmap walk");
 735
 736         if (haves_bitmap)
 737                 bitmap_and_not(wants_bitmap, haves_bitmap);
 738
 739         bitmap_git.result = wants_bitmap;
 740
 741         bitmap_free(haves_bitmap);
 742         return 0;
 743 }
 744
 745 int reuse_partial_packfile_from_bitmap(struct packed_git **packfile,
 746                                        uint32_t *entries,
 747                                        off_t *up_to)
 748 {
 749         /*
 750          * Reuse the packfile content if we need more than
 751          * 90% of its objects
 752          */
 753         static const double REUSE_PERCENT = 0.9;
 754
 755         struct bitmap *result = bitmap_git.result;
 756         uint32_t reuse_threshold;
 757         uint32_t i, reuse_objects = 0;
 758
 759         assert(result);
 760
 761         for (i = 0; i < result->word_alloc; ++i) {
 762                 if (result->words[i] != (eword_t)~0) {
 763                         reuse_objects += ewah_bit_ctz64(~result->words[i]);
 764                         break;
 765                 }
 766
 767                 reuse_objects += BITS_IN_EWORD;
 768         }
 769
 770 #ifdef GIT_BITMAP_DEBUG
 771         {
 772                 const unsigned char *sha1;
 773                 struct revindex_entry *entry;
 774
 775                 entry = &bitmap_git.reverse_index->revindex[reuse_objects];
 776                 sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
 777
 778                 fprintf(stderr, "Failed to reuse at %d (%016llx)\n",
 779                         reuse_objects, result->words[i]);
 780                 fprintf(stderr, " %s\n", sha1_to_hex(sha1));
 781         }
 782 #endif
 783
 784         if (!reuse_objects)
 785                 return -1;
 786
 787         if (reuse_objects >= bitmap_git.pack->num_objects) {
 788                 bitmap_git.reuse_objects = *entries = bitmap_git.pack->num_objects;
 789                 *up_to = -1; /* reuse the full pack */
 790                 *packfile = bitmap_git.pack;
 791                 return 0;
 792         }
 793
 794         reuse_threshold = bitmap_popcount(bitmap_git.result) * REUSE_PERCENT;
 795
 796         if (reuse_objects < reuse_threshold)
 797                 return -1;
 798
 799         bitmap_git.reuse_objects = *entries = reuse_objects;
 800         *up_to = bitmap_git.pack->revindex[reuse_objects].offset;
 801         *packfile = bitmap_git.pack;
 802
 803         return 0;
 804 }
 805
 806 void traverse_bitmap_commit_list(show_reachable_fn show_reachable)
 807 {
 808         assert(bitmap_git.result);
 809
 810         show_objects_for_type(bitmap_git.result, bitmap_git.commits,
 811                 OBJ_COMMIT, show_reachable);
 812         show_objects_for_type(bitmap_git.result, bitmap_git.trees,
 813                 OBJ_TREE, show_reachable);
 814         show_objects_for_type(bitmap_git.result, bitmap_git.blobs,
 815                 OBJ_BLOB, show_reachable);
 816         show_objects_for_type(bitmap_git.result, bitmap_git.tags,
 817                 OBJ_TAG, show_reachable);
 818
 819         show_extended_objects(bitmap_git.result, show_reachable);
 820
 821         bitmap_free(bitmap_git.result);
 822         bitmap_git.result = NULL;
 823 }
 824
 825 static uint32_t count_object_type(struct bitmap *objects,
 826                                   enum object_type type)
 827 {
 828         struct eindex *eindex = &bitmap_git.ext_index;
 829
 830         uint32_t i = 0, count = 0;
 831         struct ewah_iterator it;
 832         eword_t filter;
 833
 834         switch (type) {
 835         case OBJ_COMMIT:
 836                 ewah_iterator_init(&it, bitmap_git.commits);
 837                 break;
 838
 839         case OBJ_TREE:
 840                 ewah_iterator_init(&it, bitmap_git.trees);
 841                 break;
 842
 843         case OBJ_BLOB:
 844                 ewah_iterator_init(&it, bitmap_git.blobs);
 845                 break;
 846
 847         case OBJ_TAG:
 848                 ewah_iterator_init(&it, bitmap_git.tags);
 849                 break;
 850
 851         default:
 852                 return 0;
 853         }
 854
 855         while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) {
 856                 eword_t word = objects->words[i++] & filter;
 857                 count += ewah_bit_popcount64(word);
 858         }
 859
 860         for (i = 0; i < eindex->count; ++i) {
 861                 if (eindex->objects[i]->type == type &&
 862                         bitmap_get(objects, bitmap_git.pack->num_objects + i))
 863                         count++;
 864         }
 865
 866         return count;
 867 }
 868
 869 void count_bitmap_commit_list(uint32_t *commits, uint32_t *trees,
 870                               uint32_t *blobs, uint32_t *tags)
 871 {
 872         assert(bitmap_git.result);
 873
 874         if (commits)
 875                 *commits = count_object_type(bitmap_git.result, OBJ_COMMIT);
 876
 877         if (trees)
 878                 *trees = count_object_type(bitmap_git.result, OBJ_TREE);
 879
 880         if (blobs)
 881                 *blobs = count_object_type(bitmap_git.result, OBJ_BLOB);
 882
 883         if (tags)
 884                 *tags = count_object_type(bitmap_git.result, OBJ_TAG);
 885 }
 886
 887 struct bitmap_test_data {
 888         struct bitmap *base;
 889         struct progress *prg;
 890         size_t seen;
 891 };
 892
 893 static void test_show_object(struct object *object, const char *name,
 894                              void *data)
 895 {
 896         struct bitmap_test_data *tdata = data;
 897         int bitmap_pos;
 898
 899         bitmap_pos = bitmap_position(object->oid.hash);
 900         if (bitmap_pos < 0)
 901                 die("Object not in bitmap: %s\n", oid_to_hex(&object->oid));
 902
 903         bitmap_set(tdata->base, bitmap_pos);
 904         display_progress(tdata->prg, ++tdata->seen);
 905 }
 906
 907 static void test_show_commit(struct commit *commit, void *data)
 908 {
 909         struct bitmap_test_data *tdata = data;
 910         int bitmap_pos;
 911
 912         bitmap_pos = bitmap_position(commit->object.oid.hash);
 913         if (bitmap_pos < 0)
 914                 die("Object not in bitmap: %s\n", oid_to_hex(&commit->object.oid));
 915
 916         bitmap_set(tdata->base, bitmap_pos);
 917         display_progress(tdata->prg, ++tdata->seen);
 918 }
 919
 920 void test_bitmap_walk(struct rev_info *revs)
 921 {
 922         struct object *root;
 923         struct bitmap *result = NULL;
 924         khiter_t pos;
 925         size_t result_popcnt;
 926         struct bitmap_test_data tdata;
 927
 928         if (prepare_bitmap_git())
 929                 die("failed to load bitmap indexes");
 930
 931         if (revs->pending.nr != 1)
 932                 die("you must specify exactly one commit to test");
 933
 934         fprintf(stderr, "Bitmap v%d test (%d entries loaded)\n",
 935                 bitmap_git.version, bitmap_git.entry_count);
 936
 937         root = revs->pending.objects[0].item;
 938         pos = kh_get_sha1(bitmap_git.bitmaps, root->oid.hash);
 939
 940         if (pos < kh_end(bitmap_git.bitmaps)) {
 941                 struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, pos);
 942                 struct ewah_bitmap *bm = lookup_stored_bitmap(st);
 943
 944                 fprintf(stderr, "Found bitmap for %s. %d bits / %08x checksum\n",
 945                         oid_to_hex(&root->oid), (int)bm->bit_size, ewah_checksum(bm));
 946
 947                 result = ewah_to_bitmap(bm);
 948         }
 949
 950         if (result == NULL)
 951                 die("Commit %s doesn't have an indexed bitmap", oid_to_hex(&root->oid));
 952
 953         revs->tag_objects = 1;
 954         revs->tree_objects = 1;
 955         revs->blob_objects = 1;
 956
 957         result_popcnt = bitmap_popcount(result);
 958
 959         if (prepare_revision_walk(revs))
 960                 die("revision walk setup failed");
 961
 962         tdata.base = bitmap_new();
 963         tdata.prg = start_progress("Verifying bitmap entries", result_popcnt);
 964         tdata.seen = 0;
 965
 966         traverse_commit_list(revs, &test_show_commit, &test_show_object, &tdata);
 967
 968         stop_progress(&tdata.prg);
 969
 970         if (bitmap_equals(result, tdata.base))
 971                 fprintf(stderr, "OK!\n");
 972         else
 973                 fprintf(stderr, "Mismatch!\n");
 974
 975         bitmap_free(result);
 976 }
 977
 978 static int rebuild_bitmap(uint32_t *reposition,
 979                           struct ewah_bitmap *source,
 980                           struct bitmap *dest)
 981 {
 982         uint32_t pos = 0;
 983         struct ewah_iterator it;
 984         eword_t word;
 985
 986         ewah_iterator_init(&it, source);
 987
 988         while (ewah_iterator_next(&word, &it)) {
 989                 uint32_t offset, bit_pos;
 990
 991                 for (offset = 0; offset < BITS_IN_EWORD; ++offset) {
 992                         if ((word >> offset) == 0)
 993                                 break;
 994
 995                         offset += ewah_bit_ctz64(word >> offset);
 996
 997                         bit_pos = reposition[pos + offset];
 998                         if (bit_pos > 0)
 999                                 bitmap_set(dest, bit_pos - 1);
1000                         else /* can't reuse, we don't have the object */
1001                                 return -1;
1002                 }
1003
1004                 pos += BITS_IN_EWORD;
1005         }
1006         return 0;
1007 }
1008
1009 int rebuild_existing_bitmaps(struct packing_data *mapping,
1010                              khash_sha1 *reused_bitmaps,
1011                              int show_progress)
1012 {
1013         uint32_t i, num_objects;
1014         uint32_t *reposition;
1015         struct bitmap *rebuild;
1016         struct stored_bitmap *stored;
1017         struct progress *progress = NULL;
1018
1019         khiter_t hash_pos;
1020         int hash_ret;
1021
1022         if (prepare_bitmap_git() < 0)
1023                 return -1;
1024
1025         num_objects = bitmap_git.pack->num_objects;
1026         reposition = xcalloc(num_objects, sizeof(uint32_t));
1027
1028         for (i = 0; i < num_objects; ++i) {
1029                 const unsigned char *sha1;
1030                 struct revindex_entry *entry;
1031                 struct object_entry *oe;
1032
1033                 entry = &bitmap_git.pack->revindex[i];
1034                 sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
1035                 oe = packlist_find(mapping, sha1, NULL);
1036
1037                 if (oe)
1038                         reposition[i] = oe->in_pack_pos + 1;
1039         }
1040
1041         rebuild = bitmap_new();
1042         i = 0;
1043
1044         if (show_progress)
1045                 progress = start_progress("Reusing bitmaps", 0);
1046
1047         kh_foreach_value(bitmap_git.bitmaps, stored, {
1048                 if (stored->flags & BITMAP_FLAG_REUSE) {
1049                         if (!rebuild_bitmap(reposition,
1050                                             lookup_stored_bitmap(stored),
1051                                             rebuild)) {
1052                                 hash_pos = kh_put_sha1(reused_bitmaps,
1053                                                        stored->sha1,
1054                                                        &hash_ret);
1055                                 kh_value(reused_bitmaps, hash_pos) =
1056                                         bitmap_to_ewah(rebuild);
1057                         }
1058                         bitmap_reset(rebuild);
1059                         display_progress(progress, ++i);
1060                 }
1061         });
1062
1063         stop_progress(&progress);
1064
1065         free(reposition);
1066         bitmap_free(rebuild);
1067         return 0;
1068 }