pack-bitmap.con commit rebase: fix documentation formatting (81d395c)
   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 */
  20struct stored_bitmap {
  21        unsigned char sha1[20];
  22        struct ewah_bitmap *root;
  23        struct stored_bitmap *xor;
  24        int flags;
  25};
  26
  27/*
  28 * The currently active bitmap index. By design, repositories only have
  29 * a single bitmap index available (the index for the biggest packfile in
  30 * the repository), since bitmap indexes need full closure.
  31 *
  32 * If there is more than one bitmap index available (e.g. because of alternates),
  33 * the active bitmap index is the largest one.
  34 */
  35static struct bitmap_index {
  36        /* Packfile to which this bitmap index belongs to */
  37        struct packed_git *pack;
  38
  39        /*
  40         * Mark the first `reuse_objects` in the packfile as reused:
  41         * they will be sent as-is without using them for repacking
  42         * calculations
  43         */
  44        uint32_t reuse_objects;
  45
  46        /* mmapped buffer of the whole bitmap index */
  47        unsigned char *map;
  48        size_t map_size; /* size of the mmaped buffer */
  49        size_t map_pos; /* current position when loading the index */
  50
  51        /*
  52         * Type indexes.
  53         *
  54         * Each bitmap marks which objects in the packfile  are of the given
  55         * type. This provides type information when yielding the objects from
  56         * the packfile during a walk, which allows for better delta bases.
  57         */
  58        struct ewah_bitmap *commits;
  59        struct ewah_bitmap *trees;
  60        struct ewah_bitmap *blobs;
  61        struct ewah_bitmap *tags;
  62
  63        /* Map from SHA1 -> `stored_bitmap` for all the bitmapped commits */
  64        khash_sha1 *bitmaps;
  65
  66        /* Number of bitmapped commits */
  67        uint32_t entry_count;
  68
  69        /* Name-hash cache (or NULL if not present). */
  70        uint32_t *hashes;
  71
  72        /*
  73         * Extended index.
  74         *
  75         * When trying to perform bitmap operations with objects that are not
  76         * packed in `pack`, these objects are added to this "fake index" and
  77         * are assumed to appear at the end of the packfile for all operations
  78         */
  79        struct eindex {
  80                struct object **objects;
  81                uint32_t *hashes;
  82                uint32_t count, alloc;
  83                khash_sha1_pos *positions;
  84        } ext_index;
  85
  86        /* Bitmap result of the last performed walk */
  87        struct bitmap *result;
  88
  89        /* Version of the bitmap index */
  90        unsigned int version;
  91
  92        unsigned loaded : 1;
  93
  94} bitmap_git;
  95
  96static struct ewah_bitmap *lookup_stored_bitmap(struct stored_bitmap *st)
  97{
  98        struct ewah_bitmap *parent;
  99        struct ewah_bitmap *composed;
 100
 101        if (st->xor == NULL)
 102                return st->root;
 103
 104        composed = ewah_pool_new();
 105        parent = lookup_stored_bitmap(st->xor);
 106        ewah_xor(st->root, parent, composed);
 107
 108        ewah_pool_free(st->root);
 109        st->root = composed;
 110        st->xor = NULL;
 111
 112        return composed;
 113}
 114
 115/*
 116 * Read a bitmap from the current read position on the mmaped
 117 * index, and increase the read position accordingly
 118 */
 119static struct ewah_bitmap *read_bitmap_1(struct bitmap_index *index)
 120{
 121        struct ewah_bitmap *b = ewah_pool_new();
 122
 123        int bitmap_size = ewah_read_mmap(b,
 124                index->map + index->map_pos,
 125                index->map_size - index->map_pos);
 126
 127        if (bitmap_size < 0) {
 128                error("Failed to load bitmap index (corrupted?)");
 129                ewah_pool_free(b);
 130                return NULL;
 131        }
 132
 133        index->map_pos += bitmap_size;
 134        return b;
 135}
 136
 137static int load_bitmap_header(struct bitmap_index *index)
 138{
 139        struct bitmap_disk_header *header = (void *)index->map;
 140
 141        if (index->map_size < sizeof(*header) + 20)
 142                return error("Corrupted bitmap index (missing header data)");
 143
 144        if (memcmp(header->magic, BITMAP_IDX_SIGNATURE, sizeof(BITMAP_IDX_SIGNATURE)) != 0)
 145                return error("Corrupted bitmap index file (wrong header)");
 146
 147        index->version = ntohs(header->version);
 148        if (index->version != 1)
 149                return error("Unsupported version for bitmap index file (%d)", index->version);
 150
 151        /* Parse known bitmap format options */
 152        {
 153                uint32_t flags = ntohs(header->options);
 154
 155                if ((flags & BITMAP_OPT_FULL_DAG) == 0)
 156                        return error("Unsupported options for bitmap index file "
 157                                "(Git requires BITMAP_OPT_FULL_DAG)");
 158
 159                if (flags & BITMAP_OPT_HASH_CACHE) {
 160                        unsigned char *end = index->map + index->map_size - 20;
 161                        index->hashes = ((uint32_t *)end) - index->pack->num_objects;
 162                }
 163        }
 164
 165        index->entry_count = ntohl(header->entry_count);
 166        index->map_pos += sizeof(*header);
 167        return 0;
 168}
 169
 170static struct stored_bitmap *store_bitmap(struct bitmap_index *index,
 171                                          struct ewah_bitmap *root,
 172                                          const unsigned char *sha1,
 173                                          struct stored_bitmap *xor_with,
 174                                          int flags)
 175{
 176        struct stored_bitmap *stored;
 177        khiter_t hash_pos;
 178        int ret;
 179
 180        stored = xmalloc(sizeof(struct stored_bitmap));
 181        stored->root = root;
 182        stored->xor = xor_with;
 183        stored->flags = flags;
 184        hashcpy(stored->sha1, sha1);
 185
 186        hash_pos = kh_put_sha1(index->bitmaps, stored->sha1, &ret);
 187
 188        /* a 0 return code means the insertion succeeded with no changes,
 189         * because the SHA1 already existed on the map. this is bad, there
 190         * shouldn't be duplicated commits in the index */
 191        if (ret == 0) {
 192                error("Duplicate entry in bitmap index: %s", sha1_to_hex(sha1));
 193                return NULL;
 194        }
 195
 196        kh_value(index->bitmaps, hash_pos) = stored;
 197        return stored;
 198}
 199
 200static inline uint32_t read_be32(const unsigned char *buffer, size_t *pos)
 201{
 202        uint32_t result = get_be32(buffer + *pos);
 203        (*pos) += sizeof(result);
 204        return result;
 205}
 206
 207static inline uint8_t read_u8(const unsigned char *buffer, size_t *pos)
 208{
 209        return buffer[(*pos)++];
 210}
 211
 212#define MAX_XOR_OFFSET 160
 213
 214static int load_bitmap_entries_v1(struct bitmap_index *index)
 215{
 216        uint32_t i;
 217        struct stored_bitmap *recent_bitmaps[MAX_XOR_OFFSET] = { NULL };
 218
 219        for (i = 0; i < index->entry_count; ++i) {
 220                int xor_offset, flags;
 221                struct ewah_bitmap *bitmap = NULL;
 222                struct stored_bitmap *xor_bitmap = NULL;
 223                uint32_t commit_idx_pos;
 224                const unsigned char *sha1;
 225
 226                commit_idx_pos = read_be32(index->map, &index->map_pos);
 227                xor_offset = read_u8(index->map, &index->map_pos);
 228                flags = read_u8(index->map, &index->map_pos);
 229
 230                sha1 = nth_packed_object_sha1(index->pack, commit_idx_pos);
 231
 232                bitmap = read_bitmap_1(index);
 233                if (!bitmap)
 234                        return -1;
 235
 236                if (xor_offset > MAX_XOR_OFFSET || xor_offset > i)
 237                        return error("Corrupted bitmap pack index");
 238
 239                if (xor_offset > 0) {
 240                        xor_bitmap = recent_bitmaps[(i - xor_offset) % MAX_XOR_OFFSET];
 241
 242                        if (xor_bitmap == NULL)
 243                                return error("Invalid XOR offset in bitmap pack index");
 244                }
 245
 246                recent_bitmaps[i % MAX_XOR_OFFSET] = store_bitmap(
 247                        index, bitmap, sha1, xor_bitmap, flags);
 248        }
 249
 250        return 0;
 251}
 252
 253static char *pack_bitmap_filename(struct packed_git *p)
 254{
 255        size_t len;
 256
 257        if (!strip_suffix(p->pack_name, ".pack", &len))
 258                die("BUG: pack_name does not end in .pack");
 259        return xstrfmt("%.*s.bitmap", (int)len, p->pack_name);
 260}
 261
 262static int open_pack_bitmap_1(struct packed_git *packfile)
 263{
 264        int fd;
 265        struct stat st;
 266        char *idx_name;
 267
 268        if (open_pack_index(packfile))
 269                return -1;
 270
 271        idx_name = pack_bitmap_filename(packfile);
 272        fd = git_open(idx_name);
 273        free(idx_name);
 274
 275        if (fd < 0)
 276                return -1;
 277
 278        if (fstat(fd, &st)) {
 279                close(fd);
 280                return -1;
 281        }
 282
 283        if (bitmap_git.pack) {
 284                warning("ignoring extra bitmap file: %s", packfile->pack_name);
 285                close(fd);
 286                return -1;
 287        }
 288
 289        bitmap_git.pack = packfile;
 290        bitmap_git.map_size = xsize_t(st.st_size);
 291        bitmap_git.map = xmmap(NULL, bitmap_git.map_size, PROT_READ, MAP_PRIVATE, fd, 0);
 292        bitmap_git.map_pos = 0;
 293        close(fd);
 294
 295        if (load_bitmap_header(&bitmap_git) < 0) {
 296                munmap(bitmap_git.map, bitmap_git.map_size);
 297                bitmap_git.map = NULL;
 298                bitmap_git.map_size = 0;
 299                return -1;
 300        }
 301
 302        return 0;
 303}
 304
 305static int load_pack_bitmap(void)
 306{
 307        assert(bitmap_git.map && !bitmap_git.loaded);
 308
 309        bitmap_git.bitmaps = kh_init_sha1();
 310        bitmap_git.ext_index.positions = kh_init_sha1_pos();
 311        load_pack_revindex(bitmap_git.pack);
 312
 313        if (!(bitmap_git.commits = read_bitmap_1(&bitmap_git)) ||
 314                !(bitmap_git.trees = read_bitmap_1(&bitmap_git)) ||
 315                !(bitmap_git.blobs = read_bitmap_1(&bitmap_git)) ||
 316                !(bitmap_git.tags = read_bitmap_1(&bitmap_git)))
 317                goto failed;
 318
 319        if (load_bitmap_entries_v1(&bitmap_git) < 0)
 320                goto failed;
 321
 322        bitmap_git.loaded = 1;
 323        return 0;
 324
 325failed:
 326        munmap(bitmap_git.map, bitmap_git.map_size);
 327        bitmap_git.map = NULL;
 328        bitmap_git.map_size = 0;
 329        return -1;
 330}
 331
 332static int open_pack_bitmap(void)
 333{
 334        struct packed_git *p;
 335        int ret = -1;
 336
 337        assert(!bitmap_git.map && !bitmap_git.loaded);
 338
 339        for (p = get_packed_git(the_repository); p; p = p->next) {
 340                if (open_pack_bitmap_1(p) == 0)
 341                        ret = 0;
 342        }
 343
 344        return ret;
 345}
 346
 347int prepare_bitmap_git(void)
 348{
 349        if (bitmap_git.loaded)
 350                return 0;
 351
 352        if (!open_pack_bitmap())
 353                return load_pack_bitmap();
 354
 355        return -1;
 356}
 357
 358struct include_data {
 359        struct bitmap *base;
 360        struct bitmap *seen;
 361};
 362
 363static inline int bitmap_position_extended(const unsigned char *sha1)
 364{
 365        khash_sha1_pos *positions = bitmap_git.ext_index.positions;
 366        khiter_t pos = kh_get_sha1_pos(positions, sha1);
 367
 368        if (pos < kh_end(positions)) {
 369                int bitmap_pos = kh_value(positions, pos);
 370                return bitmap_pos + bitmap_git.pack->num_objects;
 371        }
 372
 373        return -1;
 374}
 375
 376static inline int bitmap_position_packfile(const unsigned char *sha1)
 377{
 378        off_t offset = find_pack_entry_one(sha1, bitmap_git.pack);
 379        if (!offset)
 380                return -1;
 381
 382        return find_revindex_position(bitmap_git.pack, offset);
 383}
 384
 385static int bitmap_position(const unsigned char *sha1)
 386{
 387        int pos = bitmap_position_packfile(sha1);
 388        return (pos >= 0) ? pos : bitmap_position_extended(sha1);
 389}
 390
 391static int ext_index_add_object(struct object *object, const char *name)
 392{
 393        struct eindex *eindex = &bitmap_git.ext_index;
 394
 395        khiter_t hash_pos;
 396        int hash_ret;
 397        int bitmap_pos;
 398
 399        hash_pos = kh_put_sha1_pos(eindex->positions, object->oid.hash, &hash_ret);
 400        if (hash_ret > 0) {
 401                if (eindex->count >= eindex->alloc) {
 402                        eindex->alloc = (eindex->alloc + 16) * 3 / 2;
 403                        REALLOC_ARRAY(eindex->objects, eindex->alloc);
 404                        REALLOC_ARRAY(eindex->hashes, eindex->alloc);
 405                }
 406
 407                bitmap_pos = eindex->count;
 408                eindex->objects[eindex->count] = object;
 409                eindex->hashes[eindex->count] = pack_name_hash(name);
 410                kh_value(eindex->positions, hash_pos) = bitmap_pos;
 411                eindex->count++;
 412        } else {
 413                bitmap_pos = kh_value(eindex->positions, hash_pos);
 414        }
 415
 416        return bitmap_pos + bitmap_git.pack->num_objects;
 417}
 418
 419static void show_object(struct object *object, const char *name, void *data)
 420{
 421        struct bitmap *base = data;
 422        int bitmap_pos;
 423
 424        bitmap_pos = bitmap_position(object->oid.hash);
 425
 426        if (bitmap_pos < 0)
 427                bitmap_pos = ext_index_add_object(object, name);
 428
 429        bitmap_set(base, bitmap_pos);
 430}
 431
 432static void show_commit(struct commit *commit, void *data)
 433{
 434}
 435
 436static int add_to_include_set(struct include_data *data,
 437                              const unsigned char *sha1,
 438                              int bitmap_pos)
 439{
 440        khiter_t hash_pos;
 441
 442        if (data->seen && bitmap_get(data->seen, bitmap_pos))
 443                return 0;
 444
 445        if (bitmap_get(data->base, bitmap_pos))
 446                return 0;
 447
 448        hash_pos = kh_get_sha1(bitmap_git.bitmaps, sha1);
 449        if (hash_pos < kh_end(bitmap_git.bitmaps)) {
 450                struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, hash_pos);
 451                bitmap_or_ewah(data->base, lookup_stored_bitmap(st));
 452                return 0;
 453        }
 454
 455        bitmap_set(data->base, bitmap_pos);
 456        return 1;
 457}
 458
 459static int should_include(struct commit *commit, void *_data)
 460{
 461        struct include_data *data = _data;
 462        int bitmap_pos;
 463
 464        bitmap_pos = bitmap_position(commit->object.oid.hash);
 465        if (bitmap_pos < 0)
 466                bitmap_pos = ext_index_add_object((struct object *)commit, NULL);
 467
 468        if (!add_to_include_set(data, commit->object.oid.hash, bitmap_pos)) {
 469                struct commit_list *parent = commit->parents;
 470
 471                while (parent) {
 472                        parent->item->object.flags |= SEEN;
 473                        parent = parent->next;
 474                }
 475
 476                return 0;
 477        }
 478
 479        return 1;
 480}
 481
 482static struct bitmap *find_objects(struct rev_info *revs,
 483                                   struct object_list *roots,
 484                                   struct bitmap *seen)
 485{
 486        struct bitmap *base = NULL;
 487        int needs_walk = 0;
 488
 489        struct object_list *not_mapped = NULL;
 490
 491        /*
 492         * Go through all the roots for the walk. The ones that have bitmaps
 493         * on the bitmap index will be `or`ed together to form an initial
 494         * global reachability analysis.
 495         *
 496         * The ones without bitmaps in the index will be stored in the
 497         * `not_mapped_list` for further processing.
 498         */
 499        while (roots) {
 500                struct object *object = roots->item;
 501                roots = roots->next;
 502
 503                if (object->type == OBJ_COMMIT) {
 504                        khiter_t pos = kh_get_sha1(bitmap_git.bitmaps, object->oid.hash);
 505
 506                        if (pos < kh_end(bitmap_git.bitmaps)) {
 507                                struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, pos);
 508                                struct ewah_bitmap *or_with = lookup_stored_bitmap(st);
 509
 510                                if (base == NULL)
 511                                        base = ewah_to_bitmap(or_with);
 512                                else
 513                                        bitmap_or_ewah(base, or_with);
 514
 515                                object->flags |= SEEN;
 516                                continue;
 517                        }
 518                }
 519
 520                object_list_insert(object, &not_mapped);
 521        }
 522
 523        /*
 524         * Best case scenario: We found bitmaps for all the roots,
 525         * so the resulting `or` bitmap has the full reachability analysis
 526         */
 527        if (not_mapped == NULL)
 528                return base;
 529
 530        roots = not_mapped;
 531
 532        /*
 533         * Let's iterate through all the roots that don't have bitmaps to
 534         * check if we can determine them to be reachable from the existing
 535         * global bitmap.
 536         *
 537         * If we cannot find them in the existing global bitmap, we'll need
 538         * to push them to an actual walk and run it until we can confirm
 539         * they are reachable
 540         */
 541        while (roots) {
 542                struct object *object = roots->item;
 543                int pos;
 544
 545                roots = roots->next;
 546                pos = bitmap_position(object->oid.hash);
 547
 548                if (pos < 0 || base == NULL || !bitmap_get(base, pos)) {
 549                        object->flags &= ~UNINTERESTING;
 550                        add_pending_object(revs, object, "");
 551                        needs_walk = 1;
 552                } else {
 553                        object->flags |= SEEN;
 554                }
 555        }
 556
 557        if (needs_walk) {
 558                struct include_data incdata;
 559
 560                if (base == NULL)
 561                        base = bitmap_new();
 562
 563                incdata.base = base;
 564                incdata.seen = seen;
 565
 566                revs->include_check = should_include;
 567                revs->include_check_data = &incdata;
 568
 569                if (prepare_revision_walk(revs))
 570                        die("revision walk setup failed");
 571
 572                traverse_commit_list(revs, show_commit, show_object, base);
 573        }
 574
 575        return base;
 576}
 577
 578static void show_extended_objects(struct bitmap *objects,
 579                                  show_reachable_fn show_reach)
 580{
 581        struct eindex *eindex = &bitmap_git.ext_index;
 582        uint32_t i;
 583
 584        for (i = 0; i < eindex->count; ++i) {
 585                struct object *obj;
 586
 587                if (!bitmap_get(objects, bitmap_git.pack->num_objects + i))
 588                        continue;
 589
 590                obj = eindex->objects[i];
 591                show_reach(&obj->oid, obj->type, 0, eindex->hashes[i], NULL, 0);
 592        }
 593}
 594
 595static void show_objects_for_type(
 596        struct bitmap *objects,
 597        struct ewah_bitmap *type_filter,
 598        enum object_type object_type,
 599        show_reachable_fn show_reach)
 600{
 601        size_t pos = 0, i = 0;
 602        uint32_t offset;
 603
 604        struct ewah_iterator it;
 605        eword_t filter;
 606
 607        if (bitmap_git.reuse_objects == bitmap_git.pack->num_objects)
 608                return;
 609
 610        ewah_iterator_init(&it, type_filter);
 611
 612        while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) {
 613                eword_t word = objects->words[i] & filter;
 614
 615                for (offset = 0; offset < BITS_IN_EWORD; ++offset) {
 616                        struct object_id oid;
 617                        struct revindex_entry *entry;
 618                        uint32_t hash = 0;
 619
 620                        if ((word >> offset) == 0)
 621                                break;
 622
 623                        offset += ewah_bit_ctz64(word >> offset);
 624
 625                        if (pos + offset < bitmap_git.reuse_objects)
 626                                continue;
 627
 628                        entry = &bitmap_git.pack->revindex[pos + offset];
 629                        nth_packed_object_oid(&oid, bitmap_git.pack, entry->nr);
 630
 631                        if (bitmap_git.hashes)
 632                                hash = get_be32(bitmap_git.hashes + entry->nr);
 633
 634                        show_reach(&oid, object_type, 0, hash, bitmap_git.pack, entry->offset);
 635                }
 636
 637                pos += BITS_IN_EWORD;
 638                i++;
 639        }
 640}
 641
 642static int in_bitmapped_pack(struct object_list *roots)
 643{
 644        while (roots) {
 645                struct object *object = roots->item;
 646                roots = roots->next;
 647
 648                if (find_pack_entry_one(object->oid.hash, bitmap_git.pack) > 0)
 649                        return 1;
 650        }
 651
 652        return 0;
 653}
 654
 655int prepare_bitmap_walk(struct rev_info *revs)
 656{
 657        unsigned int i;
 658
 659        struct object_list *wants = NULL;
 660        struct object_list *haves = NULL;
 661
 662        struct bitmap *wants_bitmap = NULL;
 663        struct bitmap *haves_bitmap = NULL;
 664
 665        if (!bitmap_git.loaded) {
 666                /* try to open a bitmapped pack, but don't parse it yet
 667                 * because we may not need to use it */
 668                if (open_pack_bitmap() < 0)
 669                        return -1;
 670        }
 671
 672        for (i = 0; i < revs->pending.nr; ++i) {
 673                struct object *object = revs->pending.objects[i].item;
 674
 675                if (object->type == OBJ_NONE)
 676                        parse_object_or_die(&object->oid, NULL);
 677
 678                while (object->type == OBJ_TAG) {
 679                        struct tag *tag = (struct tag *) object;
 680
 681                        if (object->flags & UNINTERESTING)
 682                                object_list_insert(object, &haves);
 683                        else
 684                                object_list_insert(object, &wants);
 685
 686                        if (!tag->tagged)
 687                                die("bad tag");
 688                        object = parse_object_or_die(&tag->tagged->oid, NULL);
 689                }
 690
 691                if (object->flags & UNINTERESTING)
 692                        object_list_insert(object, &haves);
 693                else
 694                        object_list_insert(object, &wants);
 695        }
 696
 697        /*
 698         * if we have a HAVES list, but none of those haves is contained
 699         * in the packfile that has a bitmap, we don't have anything to
 700         * optimize here
 701         */
 702        if (haves && !in_bitmapped_pack(haves))
 703                return -1;
 704
 705        /* if we don't want anything, we're done here */
 706        if (!wants)
 707                return -1;
 708
 709        /*
 710         * now we're going to use bitmaps, so load the actual bitmap entries
 711         * from disk. this is the point of no return; after this the rev_list
 712         * becomes invalidated and we must perform the revwalk through bitmaps
 713         */
 714        if (!bitmap_git.loaded && load_pack_bitmap() < 0)
 715                return -1;
 716
 717        object_array_clear(&revs->pending);
 718
 719        if (haves) {
 720                revs->ignore_missing_links = 1;
 721                haves_bitmap = find_objects(revs, haves, NULL);
 722                reset_revision_walk();
 723                revs->ignore_missing_links = 0;
 724
 725                if (haves_bitmap == NULL)
 726                        die("BUG: failed to perform bitmap walk");
 727        }
 728
 729        wants_bitmap = find_objects(revs, wants, haves_bitmap);
 730
 731        if (!wants_bitmap)
 732                die("BUG: failed to perform bitmap walk");
 733
 734        if (haves_bitmap)
 735                bitmap_and_not(wants_bitmap, haves_bitmap);
 736
 737        bitmap_git.result = wants_bitmap;
 738
 739        bitmap_free(haves_bitmap);
 740        return 0;
 741}
 742
 743int reuse_partial_packfile_from_bitmap(struct packed_git **packfile,
 744                                       uint32_t *entries,
 745                                       off_t *up_to)
 746{
 747        /*
 748         * Reuse the packfile content if we need more than
 749         * 90% of its objects
 750         */
 751        static const double REUSE_PERCENT = 0.9;
 752
 753        struct bitmap *result = bitmap_git.result;
 754        uint32_t reuse_threshold;
 755        uint32_t i, reuse_objects = 0;
 756
 757        assert(result);
 758
 759        for (i = 0; i < result->word_alloc; ++i) {
 760                if (result->words[i] != (eword_t)~0) {
 761                        reuse_objects += ewah_bit_ctz64(~result->words[i]);
 762                        break;
 763                }
 764
 765                reuse_objects += BITS_IN_EWORD;
 766        }
 767
 768#ifdef GIT_BITMAP_DEBUG
 769        {
 770                const unsigned char *sha1;
 771                struct revindex_entry *entry;
 772
 773                entry = &bitmap_git.reverse_index->revindex[reuse_objects];
 774                sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
 775
 776                fprintf(stderr, "Failed to reuse at %d (%016llx)\n",
 777                        reuse_objects, result->words[i]);
 778                fprintf(stderr, " %s\n", sha1_to_hex(sha1));
 779        }
 780#endif
 781
 782        if (!reuse_objects)
 783                return -1;
 784
 785        if (reuse_objects >= bitmap_git.pack->num_objects) {
 786                bitmap_git.reuse_objects = *entries = bitmap_git.pack->num_objects;
 787                *up_to = -1; /* reuse the full pack */
 788                *packfile = bitmap_git.pack;
 789                return 0;
 790        }
 791
 792        reuse_threshold = bitmap_popcount(bitmap_git.result) * REUSE_PERCENT;
 793
 794        if (reuse_objects < reuse_threshold)
 795                return -1;
 796
 797        bitmap_git.reuse_objects = *entries = reuse_objects;
 798        *up_to = bitmap_git.pack->revindex[reuse_objects].offset;
 799        *packfile = bitmap_git.pack;
 800
 801        return 0;
 802}
 803
 804void traverse_bitmap_commit_list(show_reachable_fn show_reachable)
 805{
 806        assert(bitmap_git.result);
 807
 808        show_objects_for_type(bitmap_git.result, bitmap_git.commits,
 809                OBJ_COMMIT, show_reachable);
 810        show_objects_for_type(bitmap_git.result, bitmap_git.trees,
 811                OBJ_TREE, show_reachable);
 812        show_objects_for_type(bitmap_git.result, bitmap_git.blobs,
 813                OBJ_BLOB, show_reachable);
 814        show_objects_for_type(bitmap_git.result, bitmap_git.tags,
 815                OBJ_TAG, show_reachable);
 816
 817        show_extended_objects(bitmap_git.result, show_reachable);
 818
 819        bitmap_free(bitmap_git.result);
 820        bitmap_git.result = NULL;
 821}
 822
 823static uint32_t count_object_type(struct bitmap *objects,
 824                                  enum object_type type)
 825{
 826        struct eindex *eindex = &bitmap_git.ext_index;
 827
 828        uint32_t i = 0, count = 0;
 829        struct ewah_iterator it;
 830        eword_t filter;
 831
 832        switch (type) {
 833        case OBJ_COMMIT:
 834                ewah_iterator_init(&it, bitmap_git.commits);
 835                break;
 836
 837        case OBJ_TREE:
 838                ewah_iterator_init(&it, bitmap_git.trees);
 839                break;
 840
 841        case OBJ_BLOB:
 842                ewah_iterator_init(&it, bitmap_git.blobs);
 843                break;
 844
 845        case OBJ_TAG:
 846                ewah_iterator_init(&it, bitmap_git.tags);
 847                break;
 848
 849        default:
 850                return 0;
 851        }
 852
 853        while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) {
 854                eword_t word = objects->words[i++] & filter;
 855                count += ewah_bit_popcount64(word);
 856        }
 857
 858        for (i = 0; i < eindex->count; ++i) {
 859                if (eindex->objects[i]->type == type &&
 860                        bitmap_get(objects, bitmap_git.pack->num_objects + i))
 861                        count++;
 862        }
 863
 864        return count;
 865}
 866
 867void count_bitmap_commit_list(uint32_t *commits, uint32_t *trees,
 868                              uint32_t *blobs, uint32_t *tags)
 869{
 870        assert(bitmap_git.result);
 871
 872        if (commits)
 873                *commits = count_object_type(bitmap_git.result, OBJ_COMMIT);
 874
 875        if (trees)
 876                *trees = count_object_type(bitmap_git.result, OBJ_TREE);
 877
 878        if (blobs)
 879                *blobs = count_object_type(bitmap_git.result, OBJ_BLOB);
 880
 881        if (tags)
 882                *tags = count_object_type(bitmap_git.result, OBJ_TAG);
 883}
 884
 885struct bitmap_test_data {
 886        struct bitmap *base;
 887        struct progress *prg;
 888        size_t seen;
 889};
 890
 891static void test_show_object(struct object *object, const char *name,
 892                             void *data)
 893{
 894        struct bitmap_test_data *tdata = data;
 895        int bitmap_pos;
 896
 897        bitmap_pos = bitmap_position(object->oid.hash);
 898        if (bitmap_pos < 0)
 899                die("Object not in bitmap: %s\n", oid_to_hex(&object->oid));
 900
 901        bitmap_set(tdata->base, bitmap_pos);
 902        display_progress(tdata->prg, ++tdata->seen);
 903}
 904
 905static void test_show_commit(struct commit *commit, void *data)
 906{
 907        struct bitmap_test_data *tdata = data;
 908        int bitmap_pos;
 909
 910        bitmap_pos = bitmap_position(commit->object.oid.hash);
 911        if (bitmap_pos < 0)
 912                die("Object not in bitmap: %s\n", oid_to_hex(&commit->object.oid));
 913
 914        bitmap_set(tdata->base, bitmap_pos);
 915        display_progress(tdata->prg, ++tdata->seen);
 916}
 917
 918void test_bitmap_walk(struct rev_info *revs)
 919{
 920        struct object *root;
 921        struct bitmap *result = NULL;
 922        khiter_t pos;
 923        size_t result_popcnt;
 924        struct bitmap_test_data tdata;
 925
 926        if (prepare_bitmap_git())
 927                die("failed to load bitmap indexes");
 928
 929        if (revs->pending.nr != 1)
 930                die("you must specify exactly one commit to test");
 931
 932        fprintf(stderr, "Bitmap v%d test (%d entries loaded)\n",
 933                bitmap_git.version, bitmap_git.entry_count);
 934
 935        root = revs->pending.objects[0].item;
 936        pos = kh_get_sha1(bitmap_git.bitmaps, root->oid.hash);
 937
 938        if (pos < kh_end(bitmap_git.bitmaps)) {
 939                struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, pos);
 940                struct ewah_bitmap *bm = lookup_stored_bitmap(st);
 941
 942                fprintf(stderr, "Found bitmap for %s. %d bits / %08x checksum\n",
 943                        oid_to_hex(&root->oid), (int)bm->bit_size, ewah_checksum(bm));
 944
 945                result = ewah_to_bitmap(bm);
 946        }
 947
 948        if (result == NULL)
 949                die("Commit %s doesn't have an indexed bitmap", oid_to_hex(&root->oid));
 950
 951        revs->tag_objects = 1;
 952        revs->tree_objects = 1;
 953        revs->blob_objects = 1;
 954
 955        result_popcnt = bitmap_popcount(result);
 956
 957        if (prepare_revision_walk(revs))
 958                die("revision walk setup failed");
 959
 960        tdata.base = bitmap_new();
 961        tdata.prg = start_progress("Verifying bitmap entries", result_popcnt);
 962        tdata.seen = 0;
 963
 964        traverse_commit_list(revs, &test_show_commit, &test_show_object, &tdata);
 965
 966        stop_progress(&tdata.prg);
 967
 968        if (bitmap_equals(result, tdata.base))
 969                fprintf(stderr, "OK!\n");
 970        else
 971                fprintf(stderr, "Mismatch!\n");
 972
 973        bitmap_free(result);
 974}
 975
 976static int rebuild_bitmap(uint32_t *reposition,
 977                          struct ewah_bitmap *source,
 978                          struct bitmap *dest)
 979{
 980        uint32_t pos = 0;
 981        struct ewah_iterator it;
 982        eword_t word;
 983
 984        ewah_iterator_init(&it, source);
 985
 986        while (ewah_iterator_next(&word, &it)) {
 987                uint32_t offset, bit_pos;
 988
 989                for (offset = 0; offset < BITS_IN_EWORD; ++offset) {
 990                        if ((word >> offset) == 0)
 991                                break;
 992
 993                        offset += ewah_bit_ctz64(word >> offset);
 994
 995                        bit_pos = reposition[pos + offset];
 996                        if (bit_pos > 0)
 997                                bitmap_set(dest, bit_pos - 1);
 998                        else /* can't reuse, we don't have the object */
 999                                return -1;
1000                }
1001
1002                pos += BITS_IN_EWORD;
1003        }
1004        return 0;
1005}
1006
1007int rebuild_existing_bitmaps(struct packing_data *mapping,
1008                             khash_sha1 *reused_bitmaps,
1009                             int show_progress)
1010{
1011        uint32_t i, num_objects;
1012        uint32_t *reposition;
1013        struct bitmap *rebuild;
1014        struct stored_bitmap *stored;
1015        struct progress *progress = NULL;
1016
1017        khiter_t hash_pos;
1018        int hash_ret;
1019
1020        if (prepare_bitmap_git() < 0)
1021                return -1;
1022
1023        num_objects = bitmap_git.pack->num_objects;
1024        reposition = xcalloc(num_objects, sizeof(uint32_t));
1025
1026        for (i = 0; i < num_objects; ++i) {
1027                const unsigned char *sha1;
1028                struct revindex_entry *entry;
1029                struct object_entry *oe;
1030
1031                entry = &bitmap_git.pack->revindex[i];
1032                sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
1033                oe = packlist_find(mapping, sha1, NULL);
1034
1035                if (oe)
1036                        reposition[i] = oe->in_pack_pos + 1;
1037        }
1038
1039        rebuild = bitmap_new();
1040        i = 0;
1041
1042        if (show_progress)
1043                progress = start_progress("Reusing bitmaps", 0);
1044
1045        kh_foreach_value(bitmap_git.bitmaps, stored, {
1046                if (stored->flags & BITMAP_FLAG_REUSE) {
1047                        if (!rebuild_bitmap(reposition,
1048                                            lookup_stored_bitmap(stored),
1049                                            rebuild)) {
1050                                hash_pos = kh_put_sha1(reused_bitmaps,
1051                                                       stored->sha1,
1052                                                       &hash_ret);
1053                                kh_value(reused_bitmaps, hash_pos) =
1054                                        bitmap_to_ewah(rebuild);
1055                        }
1056                        bitmap_reset(rebuild);
1057                        display_progress(progress, ++i);
1058                }
1059        });
1060
1061        stop_progress(&progress);
1062
1063        free(reposition);
1064        bitmap_free(rebuild);
1065        return 0;
1066}