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

   1 #include "cache.h"
   2 #include "commit.h"
   3 #include "tag.h"
   4 #include "diff.h"
   5 #include "revision.h"
   6 #include "progress.h"
   7 #include "list-objects.h"
   8 #include "pack.h"
   9 #include "pack-bitmap.h"
  10 #include "pack-revindex.h"
  11 #include "pack-objects.h"
  12 #include "packfile.h"
  13 #include "repository.h"
  14 #include "object-store.h"
  15
  16 /*
  17  * An entry on the bitmap index, representing the bitmap for a given
  18  * commit.
  19  */
  20 struct stored_bitmap {
  21         unsigned char sha1[20];
  22         struct ewah_bitmap *root;
  23         struct stored_bitmap *xor;
  24         int flags;
  25 };
  26
  27 /*
  28  * The active bitmap index for a repository. By design, repositories only have
  29  * a single bitmap index available (the index for the biggest packfile in
  30  * the repository), since bitmap indexes need full closure.
  31  *
  32  * If there is more than one bitmap index available (e.g. because of alternates),
  33  * the active bitmap index is the largest one.
  34  */
  35 struct bitmap_index {
  36         /* Packfile to which this bitmap index belongs to */
  37         struct packed_git *pack;
  38
  39         /*
  40          * Mark the first `reuse_objects` in the packfile as reused:
  41          * they will be sent as-is without using them for repacking
  42          * calculations
  43          */
  44         uint32_t reuse_objects;
  45
  46         /* mmapped buffer of the whole bitmap index */
  47         unsigned char *map;
  48         size_t map_size; /* size of the mmaped buffer */
  49         size_t map_pos; /* current position when loading the index */
  50
  51         /*
  52          * Type indexes.
  53          *
  54          * Each bitmap marks which objects in the packfile  are of the given
  55          * type. This provides type information when yielding the objects from
  56          * the packfile during a walk, which allows for better delta bases.
  57          */
  58         struct ewah_bitmap *commits;
  59         struct ewah_bitmap *trees;
  60         struct ewah_bitmap *blobs;
  61         struct ewah_bitmap *tags;
  62
  63         /* Map from 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         /* If not NULL, this is a name-hash cache pointing into map. */
  70         uint32_t *hashes;
  71
  72         /*
  73          * Extended index.
  74          *
  75          * When trying to perform bitmap operations with objects that are not
  76          * packed in `pack`, these objects are added to this "fake index" and
  77          * are assumed to appear at the end of the packfile for all operations
  78          */
  79         struct eindex {
  80                 struct object **objects;
  81                 uint32_t *hashes;
  82                 uint32_t count, alloc;
  83                 khash_sha1_pos *positions;
  84         } ext_index;
  85
  86         /* Bitmap result of the last performed walk */
  87         struct bitmap *result;
  88
  89         /* "have" bitmap from the last performed walk */
  90         struct bitmap *haves;
  91
  92         /* Version of the bitmap index */
  93         unsigned int version;
  94
  95         unsigned loaded : 1;
  96 };
  97
  98 static struct ewah_bitmap *lookup_stored_bitmap(struct stored_bitmap *st)
  99 {
 100         struct ewah_bitmap *parent;
 101         struct ewah_bitmap *composed;
 102
 103         if (st->xor == NULL)
 104                 return st->root;
 105
 106         composed = ewah_pool_new();
 107         parent = lookup_stored_bitmap(st->xor);
 108         ewah_xor(st->root, parent, composed);
 109
 110         ewah_pool_free(st->root);
 111         st->root = composed;
 112         st->xor = NULL;
 113
 114         return composed;
 115 }
 116
 117 /*
 118  * Read a bitmap from the current read position on the mmaped
 119  * index, and increase the read position accordingly
 120  */
 121 static struct ewah_bitmap *read_bitmap_1(struct bitmap_index *index)
 122 {
 123         struct ewah_bitmap *b = ewah_pool_new();
 124
 125         ssize_t bitmap_size = ewah_read_mmap(b,
 126                 index->map + index->map_pos,
 127                 index->map_size - index->map_pos);
 128
 129         if (bitmap_size < 0) {
 130                 error("Failed to load bitmap index (corrupted?)");
 131                 ewah_pool_free(b);
 132                 return NULL;
 133         }
 134
 135         index->map_pos += bitmap_size;
 136         return b;
 137 }
 138
 139 static int load_bitmap_header(struct bitmap_index *index)
 140 {
 141         struct bitmap_disk_header *header = (void *)index->map;
 142
 143         if (index->map_size < sizeof(*header) + 20)
 144                 return error("Corrupted bitmap index (missing header data)");
 145
 146         if (memcmp(header->magic, BITMAP_IDX_SIGNATURE, sizeof(BITMAP_IDX_SIGNATURE)) != 0)
 147                 return error("Corrupted bitmap index file (wrong header)");
 148
 149         index->version = ntohs(header->version);
 150         if (index->version != 1)
 151                 return error("Unsupported version for bitmap index file (%d)", index->version);
 152
 153         /* Parse known bitmap format options */
 154         {
 155                 uint32_t flags = ntohs(header->options);
 156
 157                 if ((flags & BITMAP_OPT_FULL_DAG) == 0)
 158                         return error("Unsupported options for bitmap index file "
 159                                 "(Git requires BITMAP_OPT_FULL_DAG)");
 160
 161                 if (flags & BITMAP_OPT_HASH_CACHE) {
 162                         unsigned char *end = index->map + index->map_size - 20;
 163                         index->hashes = ((uint32_t *)end) - index->pack->num_objects;
 164                 }
 165         }
 166
 167         index->entry_count = ntohl(header->entry_count);
 168         index->map_pos += sizeof(*header);
 169         return 0;
 170 }
 171
 172 static struct stored_bitmap *store_bitmap(struct bitmap_index *index,
 173                                           struct ewah_bitmap *root,
 174                                           const unsigned char *sha1,
 175                                           struct stored_bitmap *xor_with,
 176                                           int flags)
 177 {
 178         struct stored_bitmap *stored;
 179         khiter_t hash_pos;
 180         int ret;
 181
 182         stored = xmalloc(sizeof(struct stored_bitmap));
 183         stored->root = root;
 184         stored->xor = xor_with;
 185         stored->flags = flags;
 186         hashcpy(stored->sha1, sha1);
 187
 188         hash_pos = kh_put_sha1(index->bitmaps, stored->sha1, &ret);
 189
 190         /* a 0 return code means the insertion succeeded with no changes,
 191          * because the SHA1 already existed on the map. this is bad, there
 192          * shouldn't be duplicated commits in the index */
 193         if (ret == 0) {
 194                 error("Duplicate entry in bitmap index: %s", sha1_to_hex(sha1));
 195                 return NULL;
 196         }
 197
 198         kh_value(index->bitmaps, hash_pos) = stored;
 199         return stored;
 200 }
 201
 202 static inline uint32_t read_be32(const unsigned char *buffer, size_t *pos)
 203 {
 204         uint32_t result = get_be32(buffer + *pos);
 205         (*pos) += sizeof(result);
 206         return result;
 207 }
 208
 209 static inline uint8_t read_u8(const unsigned char *buffer, size_t *pos)
 210 {
 211         return buffer[(*pos)++];
 212 }
 213
 214 #define MAX_XOR_OFFSET 160
 215
 216 static int load_bitmap_entries_v1(struct bitmap_index *index)
 217 {
 218         uint32_t i;
 219         struct stored_bitmap *recent_bitmaps[MAX_XOR_OFFSET] = { NULL };
 220
 221         for (i = 0; i < index->entry_count; ++i) {
 222                 int xor_offset, flags;
 223                 struct ewah_bitmap *bitmap = NULL;
 224                 struct stored_bitmap *xor_bitmap = NULL;
 225                 uint32_t commit_idx_pos;
 226                 const unsigned char *sha1;
 227
 228                 commit_idx_pos = read_be32(index->map, &index->map_pos);
 229                 xor_offset = read_u8(index->map, &index->map_pos);
 230                 flags = read_u8(index->map, &index->map_pos);
 231
 232                 sha1 = nth_packed_object_sha1(index->pack, commit_idx_pos);
 233
 234                 bitmap = read_bitmap_1(index);
 235                 if (!bitmap)
 236                         return -1;
 237
 238                 if (xor_offset > MAX_XOR_OFFSET || xor_offset > i)
 239                         return error("Corrupted bitmap pack index");
 240
 241                 if (xor_offset > 0) {
 242                         xor_bitmap = recent_bitmaps[(i - xor_offset) % MAX_XOR_OFFSET];
 243
 244                         if (xor_bitmap == NULL)
 245                                 return error("Invalid XOR offset in bitmap pack index");
 246                 }
 247
 248                 recent_bitmaps[i % MAX_XOR_OFFSET] = store_bitmap(
 249                         index, bitmap, sha1, xor_bitmap, flags);
 250         }
 251
 252         return 0;
 253 }
 254
 255 static char *pack_bitmap_filename(struct packed_git *p)
 256 {
 257         size_t len;
 258
 259         if (!strip_suffix(p->pack_name, ".pack", &len))
 260                 BUG("pack_name does not end in .pack");
 261         return xstrfmt("%.*s.bitmap", (int)len, p->pack_name);
 262 }
 263
 264 static int open_pack_bitmap_1(struct bitmap_index *bitmap_git, struct packed_git *packfile)
 265 {
 266         int fd;
 267         struct stat st;
 268         char *idx_name;
 269
 270         if (open_pack_index(packfile))
 271                 return -1;
 272
 273         idx_name = pack_bitmap_filename(packfile);
 274         fd = git_open(idx_name);
 275         free(idx_name);
 276
 277         if (fd < 0)
 278                 return -1;
 279
 280         if (fstat(fd, &st)) {
 281                 close(fd);
 282                 return -1;
 283         }
 284
 285         if (bitmap_git->pack) {
 286                 warning("ignoring extra bitmap file: %s", packfile->pack_name);
 287                 close(fd);
 288                 return -1;
 289         }
 290
 291         bitmap_git->pack = packfile;
 292         bitmap_git->map_size = xsize_t(st.st_size);
 293         bitmap_git->map = xmmap(NULL, bitmap_git->map_size, PROT_READ, MAP_PRIVATE, fd, 0);
 294         bitmap_git->map_pos = 0;
 295         close(fd);
 296
 297         if (load_bitmap_header(bitmap_git) < 0) {
 298                 munmap(bitmap_git->map, bitmap_git->map_size);
 299                 bitmap_git->map = NULL;
 300                 bitmap_git->map_size = 0;
 301                 return -1;
 302         }
 303
 304         return 0;
 305 }
 306
 307 static int load_pack_bitmap(struct bitmap_index *bitmap_git)
 308 {
 309         assert(bitmap_git->map && !bitmap_git->loaded);
 310
 311         bitmap_git->bitmaps = kh_init_sha1();
 312         bitmap_git->ext_index.positions = kh_init_sha1_pos();
 313         load_pack_revindex(bitmap_git->pack);
 314
 315         if (!(bitmap_git->commits = read_bitmap_1(bitmap_git)) ||
 316                 !(bitmap_git->trees = read_bitmap_1(bitmap_git)) ||
 317                 !(bitmap_git->blobs = read_bitmap_1(bitmap_git)) ||
 318                 !(bitmap_git->tags = read_bitmap_1(bitmap_git)))
 319                 goto failed;
 320
 321         if (load_bitmap_entries_v1(bitmap_git) < 0)
 322                 goto failed;
 323
 324         bitmap_git->loaded = 1;
 325         return 0;
 326
 327 failed:
 328         munmap(bitmap_git->map, bitmap_git->map_size);
 329         bitmap_git->map = NULL;
 330         bitmap_git->map_size = 0;
 331         return -1;
 332 }
 333
 334 static int open_pack_bitmap(struct bitmap_index *bitmap_git)
 335 {
 336         struct packed_git *p;
 337         int ret = -1;
 338
 339         assert(!bitmap_git->map && !bitmap_git->loaded);
 340
 341         for (p = get_all_packs(the_repository); p; p = p->next) {
 342                 if (open_pack_bitmap_1(bitmap_git, p) == 0)
 343                         ret = 0;
 344         }
 345
 346         return ret;
 347 }
 348
 349 struct bitmap_index *prepare_bitmap_git(void)
 350 {
 351         struct bitmap_index *bitmap_git = xcalloc(1, sizeof(*bitmap_git));
 352
 353         if (!open_pack_bitmap(bitmap_git) && !load_pack_bitmap(bitmap_git))
 354                 return bitmap_git;
 355
 356         free_bitmap_index(bitmap_git);
 357         return NULL;
 358 }
 359
 360 struct include_data {
 361         struct bitmap_index *bitmap_git;
 362         struct bitmap *base;
 363         struct bitmap *seen;
 364 };
 365
 366 static inline int bitmap_position_extended(struct bitmap_index *bitmap_git,
 367                                            const unsigned char *sha1)
 368 {
 369         khash_sha1_pos *positions = bitmap_git->ext_index.positions;
 370         khiter_t pos = kh_get_sha1_pos(positions, sha1);
 371
 372         if (pos < kh_end(positions)) {
 373                 int bitmap_pos = kh_value(positions, pos);
 374                 return bitmap_pos + bitmap_git->pack->num_objects;
 375         }
 376
 377         return -1;
 378 }
 379
 380 static inline int bitmap_position_packfile(struct bitmap_index *bitmap_git,
 381                                            const unsigned char *sha1)
 382 {
 383         off_t offset = find_pack_entry_one(sha1, bitmap_git->pack);
 384         if (!offset)
 385                 return -1;
 386
 387         return find_revindex_position(bitmap_git->pack, offset);
 388 }
 389
 390 static int bitmap_position(struct bitmap_index *bitmap_git,
 391                            const unsigned char *sha1)
 392 {
 393         int pos = bitmap_position_packfile(bitmap_git, sha1);
 394         return (pos >= 0) ? pos : bitmap_position_extended(bitmap_git, sha1);
 395 }
 396
 397 static int ext_index_add_object(struct bitmap_index *bitmap_git,
 398                                 struct object *object, const char *name)
 399 {
 400         struct eindex *eindex = &bitmap_git->ext_index;
 401
 402         khiter_t hash_pos;
 403         int hash_ret;
 404         int bitmap_pos;
 405
 406         hash_pos = kh_put_sha1_pos(eindex->positions, object->oid.hash, &hash_ret);
 407         if (hash_ret > 0) {
 408                 if (eindex->count >= eindex->alloc) {
 409                         eindex->alloc = (eindex->alloc + 16) * 3 / 2;
 410                         REALLOC_ARRAY(eindex->objects, eindex->alloc);
 411                         REALLOC_ARRAY(eindex->hashes, eindex->alloc);
 412                 }
 413
 414                 bitmap_pos = eindex->count;
 415                 eindex->objects[eindex->count] = object;
 416                 eindex->hashes[eindex->count] = pack_name_hash(name);
 417                 kh_value(eindex->positions, hash_pos) = bitmap_pos;
 418                 eindex->count++;
 419         } else {
 420                 bitmap_pos = kh_value(eindex->positions, hash_pos);
 421         }
 422
 423         return bitmap_pos + bitmap_git->pack->num_objects;
 424 }
 425
 426 struct bitmap_show_data {
 427         struct bitmap_index *bitmap_git;
 428         struct bitmap *base;
 429 };
 430
 431 static void show_object(struct object *object, const char *name, void *data_)
 432 {
 433         struct bitmap_show_data *data = data_;
 434         int bitmap_pos;
 435
 436         bitmap_pos = bitmap_position(data->bitmap_git, object->oid.hash);
 437
 438         if (bitmap_pos < 0)
 439                 bitmap_pos = ext_index_add_object(data->bitmap_git, object,
 440                                                   name);
 441
 442         bitmap_set(data->base, bitmap_pos);
 443 }
 444
 445 static void show_commit(struct commit *commit, void *data)
 446 {
 447 }
 448
 449 static int add_to_include_set(struct bitmap_index *bitmap_git,
 450                               struct include_data *data,
 451                               const unsigned char *sha1,
 452                               int bitmap_pos)
 453 {
 454         khiter_t hash_pos;
 455
 456         if (data->seen && bitmap_get(data->seen, bitmap_pos))
 457                 return 0;
 458
 459         if (bitmap_get(data->base, bitmap_pos))
 460                 return 0;
 461
 462         hash_pos = kh_get_sha1(bitmap_git->bitmaps, sha1);
 463         if (hash_pos < kh_end(bitmap_git->bitmaps)) {
 464                 struct stored_bitmap *st = kh_value(bitmap_git->bitmaps, hash_pos);
 465                 bitmap_or_ewah(data->base, lookup_stored_bitmap(st));
 466                 return 0;
 467         }
 468
 469         bitmap_set(data->base, bitmap_pos);
 470         return 1;
 471 }
 472
 473 static int should_include(struct commit *commit, void *_data)
 474 {
 475         struct include_data *data = _data;
 476         int bitmap_pos;
 477
 478         bitmap_pos = bitmap_position(data->bitmap_git, commit->object.oid.hash);
 479         if (bitmap_pos < 0)
 480                 bitmap_pos = ext_index_add_object(data->bitmap_git,
 481                                                   (struct object *)commit,
 482                                                   NULL);
 483
 484         if (!add_to_include_set(data->bitmap_git, data, commit->object.oid.hash,
 485                                 bitmap_pos)) {
 486                 struct commit_list *parent = commit->parents;
 487
 488                 while (parent) {
 489                         parent->item->object.flags |= SEEN;
 490                         parent = parent->next;
 491                 }
 492
 493                 return 0;
 494         }
 495
 496         return 1;
 497 }
 498
 499 static struct bitmap *find_objects(struct bitmap_index *bitmap_git,
 500                                    struct rev_info *revs,
 501                                    struct object_list *roots,
 502                                    struct bitmap *seen)
 503 {
 504         struct bitmap *base = NULL;
 505         int needs_walk = 0;
 506
 507         struct object_list *not_mapped = NULL;
 508
 509         /*
 510          * Go through all the roots for the walk. The ones that have bitmaps
 511          * on the bitmap index will be `or`ed together to form an initial
 512          * global reachability analysis.
 513          *
 514          * The ones without bitmaps in the index will be stored in the
 515          * `not_mapped_list` for further processing.
 516          */
 517         while (roots) {
 518                 struct object *object = roots->item;
 519                 roots = roots->next;
 520
 521                 if (object->type == OBJ_COMMIT) {
 522                         khiter_t pos = kh_get_sha1(bitmap_git->bitmaps, object->oid.hash);
 523
 524                         if (pos < kh_end(bitmap_git->bitmaps)) {
 525                                 struct stored_bitmap *st = kh_value(bitmap_git->bitmaps, pos);
 526                                 struct ewah_bitmap *or_with = lookup_stored_bitmap(st);
 527
 528                                 if (base == NULL)
 529                                         base = ewah_to_bitmap(or_with);
 530                                 else
 531                                         bitmap_or_ewah(base, or_with);
 532
 533                                 object->flags |= SEEN;
 534                                 continue;
 535                         }
 536                 }
 537
 538                 object_list_insert(object, &not_mapped);
 539         }
 540
 541         /*
 542          * Best case scenario: We found bitmaps for all the roots,
 543          * so the resulting `or` bitmap has the full reachability analysis
 544          */
 545         if (not_mapped == NULL)
 546                 return base;
 547
 548         roots = not_mapped;
 549
 550         /*
 551          * Let's iterate through all the roots that don't have bitmaps to
 552          * check if we can determine them to be reachable from the existing
 553          * global bitmap.
 554          *
 555          * If we cannot find them in the existing global bitmap, we'll need
 556          * to push them to an actual walk and run it until we can confirm
 557          * they are reachable
 558          */
 559         while (roots) {
 560                 struct object *object = roots->item;
 561                 int pos;
 562
 563                 roots = roots->next;
 564                 pos = bitmap_position(bitmap_git, object->oid.hash);
 565
 566                 if (pos < 0 || base == NULL || !bitmap_get(base, pos)) {
 567                         object->flags &= ~UNINTERESTING;
 568                         add_pending_object(revs, object, "");
 569                         needs_walk = 1;
 570                 } else {
 571                         object->flags |= SEEN;
 572                 }
 573         }
 574
 575         if (needs_walk) {
 576                 struct include_data incdata;
 577                 struct bitmap_show_data show_data;
 578
 579                 if (base == NULL)
 580                         base = bitmap_new();
 581
 582                 incdata.bitmap_git = bitmap_git;
 583                 incdata.base = base;
 584                 incdata.seen = seen;
 585
 586                 revs->include_check = should_include;
 587                 revs->include_check_data = &incdata;
 588
 589                 if (prepare_revision_walk(revs))
 590                         die("revision walk setup failed");
 591
 592                 show_data.bitmap_git = bitmap_git;
 593                 show_data.base = base;
 594
 595                 traverse_commit_list(revs, show_commit, show_object,
 596                                      &show_data);
 597         }
 598
 599         return base;
 600 }
 601
 602 static void show_extended_objects(struct bitmap_index *bitmap_git,
 603                                   show_reachable_fn show_reach)
 604 {
 605         struct bitmap *objects = bitmap_git->result;
 606         struct eindex *eindex = &bitmap_git->ext_index;
 607         uint32_t i;
 608
 609         for (i = 0; i < eindex->count; ++i) {
 610                 struct object *obj;
 611
 612                 if (!bitmap_get(objects, bitmap_git->pack->num_objects + i))
 613                         continue;
 614
 615                 obj = eindex->objects[i];
 616                 show_reach(&obj->oid, obj->type, 0, eindex->hashes[i], NULL, 0);
 617         }
 618 }
 619
 620 static void show_objects_for_type(
 621         struct bitmap_index *bitmap_git,
 622         struct ewah_bitmap *type_filter,
 623         enum object_type object_type,
 624         show_reachable_fn show_reach)
 625 {
 626         size_t pos = 0, i = 0;
 627         uint32_t offset;
 628
 629         struct ewah_iterator it;
 630         eword_t filter;
 631
 632         struct bitmap *objects = bitmap_git->result;
 633
 634         if (bitmap_git->reuse_objects == bitmap_git->pack->num_objects)
 635                 return;
 636
 637         ewah_iterator_init(&it, type_filter);
 638
 639         while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) {
 640                 eword_t word = objects->words[i] & filter;
 641
 642                 for (offset = 0; offset < BITS_IN_EWORD; ++offset) {
 643                         struct object_id oid;
 644                         struct revindex_entry *entry;
 645                         uint32_t hash = 0;
 646
 647                         if ((word >> offset) == 0)
 648                                 break;
 649
 650                         offset += ewah_bit_ctz64(word >> offset);
 651
 652                         if (pos + offset < bitmap_git->reuse_objects)
 653                                 continue;
 654
 655                         entry = &bitmap_git->pack->revindex[pos + offset];
 656                         nth_packed_object_oid(&oid, bitmap_git->pack, entry->nr);
 657
 658                         if (bitmap_git->hashes)
 659                                 hash = get_be32(bitmap_git->hashes + entry->nr);
 660
 661                         show_reach(&oid, object_type, 0, hash, bitmap_git->pack, entry->offset);
 662                 }
 663
 664                 pos += BITS_IN_EWORD;
 665                 i++;
 666         }
 667 }
 668
 669 static int in_bitmapped_pack(struct bitmap_index *bitmap_git,
 670                              struct object_list *roots)
 671 {
 672         while (roots) {
 673                 struct object *object = roots->item;
 674                 roots = roots->next;
 675
 676                 if (find_pack_entry_one(object->oid.hash, bitmap_git->pack) > 0)
 677                         return 1;
 678         }
 679
 680         return 0;
 681 }
 682
 683 struct bitmap_index *prepare_bitmap_walk(struct rev_info *revs)
 684 {
 685         unsigned int i;
 686
 687         struct object_list *wants = NULL;
 688         struct object_list *haves = NULL;
 689
 690         struct bitmap *wants_bitmap = NULL;
 691         struct bitmap *haves_bitmap = NULL;
 692
 693         struct bitmap_index *bitmap_git = xcalloc(1, sizeof(*bitmap_git));
 694         /* try to open a bitmapped pack, but don't parse it yet
 695          * because we may not need to use it */
 696         if (open_pack_bitmap(bitmap_git) < 0)
 697                 goto cleanup;
 698
 699         for (i = 0; i < revs->pending.nr; ++i) {
 700                 struct object *object = revs->pending.objects[i].item;
 701
 702                 if (object->type == OBJ_NONE)
 703                         parse_object_or_die(&object->oid, NULL);
 704
 705                 while (object->type == OBJ_TAG) {
 706                         struct tag *tag = (struct tag *) object;
 707
 708                         if (object->flags & UNINTERESTING)
 709                                 object_list_insert(object, &haves);
 710                         else
 711                                 object_list_insert(object, &wants);
 712
 713                         if (!tag->tagged)
 714                                 die("bad tag");
 715                         object = parse_object_or_die(&tag->tagged->oid, NULL);
 716                 }
 717
 718                 if (object->flags & UNINTERESTING)
 719                         object_list_insert(object, &haves);
 720                 else
 721                         object_list_insert(object, &wants);
 722         }
 723
 724         /*
 725          * if we have a HAVES list, but none of those haves is contained
 726          * in the packfile that has a bitmap, we don't have anything to
 727          * optimize here
 728          */
 729         if (haves && !in_bitmapped_pack(bitmap_git, haves))
 730                 goto cleanup;
 731
 732         /* if we don't want anything, we're done here */
 733         if (!wants)
 734                 goto cleanup;
 735
 736         /*
 737          * now we're going to use bitmaps, so load the actual bitmap entries
 738          * from disk. this is the point of no return; after this the rev_list
 739          * becomes invalidated and we must perform the revwalk through bitmaps
 740          */
 741         if (!bitmap_git->loaded && load_pack_bitmap(bitmap_git) < 0)
 742                 goto cleanup;
 743
 744         object_array_clear(&revs->pending);
 745
 746         if (haves) {
 747                 revs->ignore_missing_links = 1;
 748                 haves_bitmap = find_objects(bitmap_git, revs, haves, NULL);
 749                 reset_revision_walk();
 750                 revs->ignore_missing_links = 0;
 751
 752                 if (haves_bitmap == NULL)
 753                         BUG("failed to perform bitmap walk");
 754         }
 755
 756         wants_bitmap = find_objects(bitmap_git, revs, wants, haves_bitmap);
 757
 758         if (!wants_bitmap)
 759                 BUG("failed to perform bitmap walk");
 760
 761         if (haves_bitmap)
 762                 bitmap_and_not(wants_bitmap, haves_bitmap);
 763
 764         bitmap_git->result = wants_bitmap;
 765         bitmap_git->haves = haves_bitmap;
 766
 767         return bitmap_git;
 768
 769 cleanup:
 770         free_bitmap_index(bitmap_git);
 771         return NULL;
 772 }
 773
 774 int reuse_partial_packfile_from_bitmap(struct bitmap_index *bitmap_git,
 775                                        struct packed_git **packfile,
 776                                        uint32_t *entries,
 777                                        off_t *up_to)
 778 {
 779         /*
 780          * Reuse the packfile content if we need more than
 781          * 90% of its objects
 782          */
 783         static const double REUSE_PERCENT = 0.9;
 784
 785         struct bitmap *result = bitmap_git->result;
 786         uint32_t reuse_threshold;
 787         uint32_t i, reuse_objects = 0;
 788
 789         assert(result);
 790
 791         for (i = 0; i < result->word_alloc; ++i) {
 792                 if (result->words[i] != (eword_t)~0) {
 793                         reuse_objects += ewah_bit_ctz64(~result->words[i]);
 794                         break;
 795                 }
 796
 797                 reuse_objects += BITS_IN_EWORD;
 798         }
 799
 800 #ifdef GIT_BITMAP_DEBUG
 801         {
 802                 const unsigned char *sha1;
 803                 struct revindex_entry *entry;
 804
 805                 entry = &bitmap_git->reverse_index->revindex[reuse_objects];
 806                 sha1 = nth_packed_object_sha1(bitmap_git->pack, entry->nr);
 807
 808                 fprintf(stderr, "Failed to reuse at %d (%016llx)\n",
 809                         reuse_objects, result->words[i]);
 810                 fprintf(stderr, " %s\n", sha1_to_hex(sha1));
 811         }
 812 #endif
 813
 814         if (!reuse_objects)
 815                 return -1;
 816
 817         if (reuse_objects >= bitmap_git->pack->num_objects) {
 818                 bitmap_git->reuse_objects = *entries = bitmap_git->pack->num_objects;
 819                 *up_to = -1; /* reuse the full pack */
 820                 *packfile = bitmap_git->pack;
 821                 return 0;
 822         }
 823
 824         reuse_threshold = bitmap_popcount(bitmap_git->result) * REUSE_PERCENT;
 825
 826         if (reuse_objects < reuse_threshold)
 827                 return -1;
 828
 829         bitmap_git->reuse_objects = *entries = reuse_objects;
 830         *up_to = bitmap_git->pack->revindex[reuse_objects].offset;
 831         *packfile = bitmap_git->pack;
 832
 833         return 0;
 834 }
 835
 836 void traverse_bitmap_commit_list(struct bitmap_index *bitmap_git,
 837                                  show_reachable_fn show_reachable)
 838 {
 839         assert(bitmap_git->result);
 840
 841         show_objects_for_type(bitmap_git, bitmap_git->commits,
 842                 OBJ_COMMIT, show_reachable);
 843         show_objects_for_type(bitmap_git, bitmap_git->trees,
 844                 OBJ_TREE, show_reachable);
 845         show_objects_for_type(bitmap_git, bitmap_git->blobs,
 846                 OBJ_BLOB, show_reachable);
 847         show_objects_for_type(bitmap_git, bitmap_git->tags,
 848                 OBJ_TAG, show_reachable);
 849
 850         show_extended_objects(bitmap_git, show_reachable);
 851
 852         bitmap_free(bitmap_git->result);
 853         bitmap_git->result = NULL;
 854 }
 855
 856 static uint32_t count_object_type(struct bitmap_index *bitmap_git,
 857                                   enum object_type type)
 858 {
 859         struct bitmap *objects = bitmap_git->result;
 860         struct eindex *eindex = &bitmap_git->ext_index;
 861
 862         uint32_t i = 0, count = 0;
 863         struct ewah_iterator it;
 864         eword_t filter;
 865
 866         switch (type) {
 867         case OBJ_COMMIT:
 868                 ewah_iterator_init(&it, bitmap_git->commits);
 869                 break;
 870
 871         case OBJ_TREE:
 872                 ewah_iterator_init(&it, bitmap_git->trees);
 873                 break;
 874
 875         case OBJ_BLOB:
 876                 ewah_iterator_init(&it, bitmap_git->blobs);
 877                 break;
 878
 879         case OBJ_TAG:
 880                 ewah_iterator_init(&it, bitmap_git->tags);
 881                 break;
 882
 883         default:
 884                 return 0;
 885         }
 886
 887         while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) {
 888                 eword_t word = objects->words[i++] & filter;
 889                 count += ewah_bit_popcount64(word);
 890         }
 891
 892         for (i = 0; i < eindex->count; ++i) {
 893                 if (eindex->objects[i]->type == type &&
 894                         bitmap_get(objects, bitmap_git->pack->num_objects + i))
 895                         count++;
 896         }
 897
 898         return count;
 899 }
 900
 901 void count_bitmap_commit_list(struct bitmap_index *bitmap_git,
 902                               uint32_t *commits, uint32_t *trees,
 903                               uint32_t *blobs, uint32_t *tags)
 904 {
 905         assert(bitmap_git->result);
 906
 907         if (commits)
 908                 *commits = count_object_type(bitmap_git, OBJ_COMMIT);
 909
 910         if (trees)
 911                 *trees = count_object_type(bitmap_git, OBJ_TREE);
 912
 913         if (blobs)
 914                 *blobs = count_object_type(bitmap_git, OBJ_BLOB);
 915
 916         if (tags)
 917                 *tags = count_object_type(bitmap_git, OBJ_TAG);
 918 }
 919
 920 struct bitmap_test_data {
 921         struct bitmap_index *bitmap_git;
 922         struct bitmap *base;
 923         struct progress *prg;
 924         size_t seen;
 925 };
 926
 927 static void test_show_object(struct object *object, const char *name,
 928                              void *data)
 929 {
 930         struct bitmap_test_data *tdata = data;
 931         int bitmap_pos;
 932
 933         bitmap_pos = bitmap_position(tdata->bitmap_git, object->oid.hash);
 934         if (bitmap_pos < 0)
 935                 die("Object not in bitmap: %s\n", oid_to_hex(&object->oid));
 936
 937         bitmap_set(tdata->base, bitmap_pos);
 938         display_progress(tdata->prg, ++tdata->seen);
 939 }
 940
 941 static void test_show_commit(struct commit *commit, void *data)
 942 {
 943         struct bitmap_test_data *tdata = data;
 944         int bitmap_pos;
 945
 946         bitmap_pos = bitmap_position(tdata->bitmap_git,
 947                                      commit->object.oid.hash);
 948         if (bitmap_pos < 0)
 949                 die("Object not in bitmap: %s\n", oid_to_hex(&commit->object.oid));
 950
 951         bitmap_set(tdata->base, bitmap_pos);
 952         display_progress(tdata->prg, ++tdata->seen);
 953 }
 954
 955 void test_bitmap_walk(struct rev_info *revs)
 956 {
 957         struct object *root;
 958         struct bitmap *result = NULL;
 959         khiter_t pos;
 960         size_t result_popcnt;
 961         struct bitmap_test_data tdata;
 962         struct bitmap_index *bitmap_git;
 963
 964         if (!(bitmap_git = prepare_bitmap_git()))
 965                 die("failed to load bitmap indexes");
 966
 967         if (revs->pending.nr != 1)
 968                 die("you must specify exactly one commit to test");
 969
 970         fprintf(stderr, "Bitmap v%d test (%d entries loaded)\n",
 971                 bitmap_git->version, bitmap_git->entry_count);
 972
 973         root = revs->pending.objects[0].item;
 974         pos = kh_get_sha1(bitmap_git->bitmaps, root->oid.hash);
 975
 976         if (pos < kh_end(bitmap_git->bitmaps)) {
 977                 struct stored_bitmap *st = kh_value(bitmap_git->bitmaps, pos);
 978                 struct ewah_bitmap *bm = lookup_stored_bitmap(st);
 979
 980                 fprintf(stderr, "Found bitmap for %s. %d bits / %08x checksum\n",
 981                         oid_to_hex(&root->oid), (int)bm->bit_size, ewah_checksum(bm));
 982
 983                 result = ewah_to_bitmap(bm);
 984         }
 985
 986         if (result == NULL)
 987                 die("Commit %s doesn't have an indexed bitmap", oid_to_hex(&root->oid));
 988
 989         revs->tag_objects = 1;
 990         revs->tree_objects = 1;
 991         revs->blob_objects = 1;
 992
 993         result_popcnt = bitmap_popcount(result);
 994
 995         if (prepare_revision_walk(revs))
 996                 die("revision walk setup failed");
 997
 998         tdata.bitmap_git = bitmap_git;
 999         tdata.base = bitmap_new();
1000         tdata.prg = start_progress("Verifying bitmap entries", result_popcnt);
1001         tdata.seen = 0;
1002
1003         traverse_commit_list(revs, &test_show_commit, &test_show_object, &tdata);
1004
1005         stop_progress(&tdata.prg);
1006
1007         if (bitmap_equals(result, tdata.base))
1008                 fprintf(stderr, "OK!\n");
1009         else
1010                 fprintf(stderr, "Mismatch!\n");
1011
1012         free_bitmap_index(bitmap_git);
1013 }
1014
1015 static int rebuild_bitmap(uint32_t *reposition,
1016                           struct ewah_bitmap *source,
1017                           struct bitmap *dest)
1018 {
1019         uint32_t pos = 0;
1020         struct ewah_iterator it;
1021         eword_t word;
1022
1023         ewah_iterator_init(&it, source);
1024
1025         while (ewah_iterator_next(&word, &it)) {
1026                 uint32_t offset, bit_pos;
1027
1028                 for (offset = 0; offset < BITS_IN_EWORD; ++offset) {
1029                         if ((word >> offset) == 0)
1030                                 break;
1031
1032                         offset += ewah_bit_ctz64(word >> offset);
1033
1034                         bit_pos = reposition[pos + offset];
1035                         if (bit_pos > 0)
1036                                 bitmap_set(dest, bit_pos - 1);
1037                         else /* can't reuse, we don't have the object */
1038                                 return -1;
1039                 }
1040
1041                 pos += BITS_IN_EWORD;
1042         }
1043         return 0;
1044 }
1045
1046 int rebuild_existing_bitmaps(struct bitmap_index *bitmap_git,
1047                              struct packing_data *mapping,
1048                              khash_sha1 *reused_bitmaps,
1049                              int show_progress)
1050 {
1051         uint32_t i, num_objects;
1052         uint32_t *reposition;
1053         struct bitmap *rebuild;
1054         struct stored_bitmap *stored;
1055         struct progress *progress = NULL;
1056
1057         khiter_t hash_pos;
1058         int hash_ret;
1059
1060         num_objects = bitmap_git->pack->num_objects;
1061         reposition = xcalloc(num_objects, sizeof(uint32_t));
1062
1063         for (i = 0; i < num_objects; ++i) {
1064                 const unsigned char *sha1;
1065                 struct revindex_entry *entry;
1066                 struct object_entry *oe;
1067
1068                 entry = &bitmap_git->pack->revindex[i];
1069                 sha1 = nth_packed_object_sha1(bitmap_git->pack, entry->nr);
1070                 oe = packlist_find(mapping, sha1, NULL);
1071
1072                 if (oe)
1073                         reposition[i] = oe_in_pack_pos(mapping, oe) + 1;
1074         }
1075
1076         rebuild = bitmap_new();
1077         i = 0;
1078
1079         if (show_progress)
1080                 progress = start_progress("Reusing bitmaps", 0);
1081
1082         kh_foreach_value(bitmap_git->bitmaps, stored, {
1083                 if (stored->flags & BITMAP_FLAG_REUSE) {
1084                         if (!rebuild_bitmap(reposition,
1085                                             lookup_stored_bitmap(stored),
1086                                             rebuild)) {
1087                                 hash_pos = kh_put_sha1(reused_bitmaps,
1088                                                        stored->sha1,
1089                                                        &hash_ret);
1090                                 kh_value(reused_bitmaps, hash_pos) =
1091                                         bitmap_to_ewah(rebuild);
1092                         }
1093                         bitmap_reset(rebuild);
1094                         display_progress(progress, ++i);
1095                 }
1096         });
1097
1098         stop_progress(&progress);
1099
1100         free(reposition);
1101         bitmap_free(rebuild);
1102         return 0;
1103 }
1104
1105 void free_bitmap_index(struct bitmap_index *b)
1106 {
1107         if (!b)
1108                 return;
1109
1110         if (b->map)
1111                 munmap(b->map, b->map_size);
1112         ewah_pool_free(b->commits);
1113         ewah_pool_free(b->trees);
1114         ewah_pool_free(b->blobs);
1115         ewah_pool_free(b->tags);
1116         kh_destroy_sha1(b->bitmaps);
1117         free(b->ext_index.objects);
1118         free(b->ext_index.hashes);
1119         bitmap_free(b->result);
1120         bitmap_free(b->haves);
1121         free(b);
1122 }
1123
1124 int bitmap_has_sha1_in_uninteresting(struct bitmap_index *bitmap_git,
1125                                      const unsigned char *sha1)
1126 {
1127         int pos;
1128
1129         if (!bitmap_git)
1130                 return 0; /* no bitmap loaded */
1131         if (!bitmap_git->result)
1132                 BUG("failed to perform bitmap walk before querying");
1133         if (!bitmap_git->haves)
1134                 return 0; /* walk had no "haves" */
1135
1136         pos = bitmap_position_packfile(bitmap_git, sha1);
1137         if (pos < 0)
1138                 return 0;
1139
1140         return bitmap_get(bitmap_git->haves, pos);
1141 }