pack-bitmap.con commit Merge branch 'sg/help-group' (6dec263)
   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 */
  17struct 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 */
  32static struct bitmap_index {
  33        /* Packfile to which this bitmap index belongs to */
  34        struct packed_git *pack;
  35
  36        /* reverse index for the packfile */
  37        struct pack_revindex *reverse_index;
  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        char *idx_name;
 256        int len;
 257
 258        len = strlen(p->pack_name) - strlen(".pack");
 259        idx_name = xmalloc(len + strlen(".bitmap") + 1);
 260
 261        memcpy(idx_name, p->pack_name, len);
 262        memcpy(idx_name + len, ".bitmap", strlen(".bitmap") + 1);
 263
 264        return idx_name;
 265}
 266
 267static int open_pack_bitmap_1(struct packed_git *packfile)
 268{
 269        int fd;
 270        struct stat st;
 271        char *idx_name;
 272
 273        if (open_pack_index(packfile))
 274                return -1;
 275
 276        idx_name = pack_bitmap_filename(packfile);
 277        fd = git_open_noatime(idx_name);
 278        free(idx_name);
 279
 280        if (fd < 0)
 281                return -1;
 282
 283        if (fstat(fd, &st)) {
 284                close(fd);
 285                return -1;
 286        }
 287
 288        if (bitmap_git.pack) {
 289                warning("ignoring extra bitmap file: %s", packfile->pack_name);
 290                close(fd);
 291                return -1;
 292        }
 293
 294        bitmap_git.pack = packfile;
 295        bitmap_git.map_size = xsize_t(st.st_size);
 296        bitmap_git.map = xmmap(NULL, bitmap_git.map_size, PROT_READ, MAP_PRIVATE, fd, 0);
 297        bitmap_git.map_pos = 0;
 298        close(fd);
 299
 300        if (load_bitmap_header(&bitmap_git) < 0) {
 301                munmap(bitmap_git.map, bitmap_git.map_size);
 302                bitmap_git.map = NULL;
 303                bitmap_git.map_size = 0;
 304                return -1;
 305        }
 306
 307        return 0;
 308}
 309
 310static int load_pack_bitmap(void)
 311{
 312        assert(bitmap_git.map && !bitmap_git.loaded);
 313
 314        bitmap_git.bitmaps = kh_init_sha1();
 315        bitmap_git.ext_index.positions = kh_init_sha1_pos();
 316        bitmap_git.reverse_index = revindex_for_pack(bitmap_git.pack);
 317
 318        if (!(bitmap_git.commits = read_bitmap_1(&bitmap_git)) ||
 319                !(bitmap_git.trees = read_bitmap_1(&bitmap_git)) ||
 320                !(bitmap_git.blobs = read_bitmap_1(&bitmap_git)) ||
 321                !(bitmap_git.tags = read_bitmap_1(&bitmap_git)))
 322                goto failed;
 323
 324        if (load_bitmap_entries_v1(&bitmap_git) < 0)
 325                goto failed;
 326
 327        bitmap_git.loaded = 1;
 328        return 0;
 329
 330failed:
 331        munmap(bitmap_git.map, bitmap_git.map_size);
 332        bitmap_git.map = NULL;
 333        bitmap_git.map_size = 0;
 334        return -1;
 335}
 336
 337static int open_pack_bitmap(void)
 338{
 339        struct packed_git *p;
 340        int ret = -1;
 341
 342        assert(!bitmap_git.map && !bitmap_git.loaded);
 343
 344        prepare_packed_git();
 345        for (p = packed_git; p; p = p->next) {
 346                if (open_pack_bitmap_1(p) == 0)
 347                        ret = 0;
 348        }
 349
 350        return ret;
 351}
 352
 353int prepare_bitmap_git(void)
 354{
 355        if (bitmap_git.loaded)
 356                return 0;
 357
 358        if (!open_pack_bitmap())
 359                return load_pack_bitmap();
 360
 361        return -1;
 362}
 363
 364struct include_data {
 365        struct bitmap *base;
 366        struct bitmap *seen;
 367};
 368
 369static inline int bitmap_position_extended(const unsigned char *sha1)
 370{
 371        khash_sha1_pos *positions = bitmap_git.ext_index.positions;
 372        khiter_t pos = kh_get_sha1_pos(positions, sha1);
 373
 374        if (pos < kh_end(positions)) {
 375                int bitmap_pos = kh_value(positions, pos);
 376                return bitmap_pos + bitmap_git.pack->num_objects;
 377        }
 378
 379        return -1;
 380}
 381
 382static inline int bitmap_position_packfile(const unsigned char *sha1)
 383{
 384        off_t offset = find_pack_entry_one(sha1, bitmap_git.pack);
 385        if (!offset)
 386                return -1;
 387
 388        return find_revindex_position(bitmap_git.reverse_index, offset);
 389}
 390
 391static int bitmap_position(const unsigned char *sha1)
 392{
 393        int pos = bitmap_position_packfile(sha1);
 394        return (pos >= 0) ? pos : bitmap_position_extended(sha1);
 395}
 396
 397static int ext_index_add_object(struct object *object, const char *name)
 398{
 399        struct eindex *eindex = &bitmap_git.ext_index;
 400
 401        khiter_t hash_pos;
 402        int hash_ret;
 403        int bitmap_pos;
 404
 405        hash_pos = kh_put_sha1_pos(eindex->positions, object->sha1, &hash_ret);
 406        if (hash_ret > 0) {
 407                if (eindex->count >= eindex->alloc) {
 408                        eindex->alloc = (eindex->alloc + 16) * 3 / 2;
 409                        REALLOC_ARRAY(eindex->objects, eindex->alloc);
 410                        REALLOC_ARRAY(eindex->hashes, eindex->alloc);
 411                }
 412
 413                bitmap_pos = eindex->count;
 414                eindex->objects[eindex->count] = object;
 415                eindex->hashes[eindex->count] = pack_name_hash(name);
 416                kh_value(eindex->positions, hash_pos) = bitmap_pos;
 417                eindex->count++;
 418        } else {
 419                bitmap_pos = kh_value(eindex->positions, hash_pos);
 420        }
 421
 422        return bitmap_pos + bitmap_git.pack->num_objects;
 423}
 424
 425static void show_object(struct object *object, const struct name_path *path,
 426                        const char *last, void *data)
 427{
 428        struct bitmap *base = data;
 429        int bitmap_pos;
 430
 431        bitmap_pos = bitmap_position(object->sha1);
 432
 433        if (bitmap_pos < 0) {
 434                char *name = path_name(path, last);
 435                bitmap_pos = ext_index_add_object(object, name);
 436                free(name);
 437        }
 438
 439        bitmap_set(base, bitmap_pos);
 440}
 441
 442static void show_commit(struct commit *commit, void *data)
 443{
 444}
 445
 446static int add_to_include_set(struct include_data *data,
 447                              const unsigned char *sha1,
 448                              int bitmap_pos)
 449{
 450        khiter_t hash_pos;
 451
 452        if (data->seen && bitmap_get(data->seen, bitmap_pos))
 453                return 0;
 454
 455        if (bitmap_get(data->base, bitmap_pos))
 456                return 0;
 457
 458        hash_pos = kh_get_sha1(bitmap_git.bitmaps, sha1);
 459        if (hash_pos < kh_end(bitmap_git.bitmaps)) {
 460                struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, hash_pos);
 461                bitmap_or_ewah(data->base, lookup_stored_bitmap(st));
 462                return 0;
 463        }
 464
 465        bitmap_set(data->base, bitmap_pos);
 466        return 1;
 467}
 468
 469static int should_include(struct commit *commit, void *_data)
 470{
 471        struct include_data *data = _data;
 472        int bitmap_pos;
 473
 474        bitmap_pos = bitmap_position(commit->object.sha1);
 475        if (bitmap_pos < 0)
 476                bitmap_pos = ext_index_add_object((struct object *)commit, NULL);
 477
 478        if (!add_to_include_set(data, commit->object.sha1, bitmap_pos)) {
 479                struct commit_list *parent = commit->parents;
 480
 481                while (parent) {
 482                        parent->item->object.flags |= SEEN;
 483                        parent = parent->next;
 484                }
 485
 486                return 0;
 487        }
 488
 489        return 1;
 490}
 491
 492static struct bitmap *find_objects(struct rev_info *revs,
 493                                   struct object_list *roots,
 494                                   struct bitmap *seen)
 495{
 496        struct bitmap *base = NULL;
 497        int needs_walk = 0;
 498
 499        struct object_list *not_mapped = NULL;
 500
 501        /*
 502         * Go through all the roots for the walk. The ones that have bitmaps
 503         * on the bitmap index will be `or`ed together to form an initial
 504         * global reachability analysis.
 505         *
 506         * The ones without bitmaps in the index will be stored in the
 507         * `not_mapped_list` for further processing.
 508         */
 509        while (roots) {
 510                struct object *object = roots->item;
 511                roots = roots->next;
 512
 513                if (object->type == OBJ_COMMIT) {
 514                        khiter_t pos = kh_get_sha1(bitmap_git.bitmaps, object->sha1);
 515
 516                        if (pos < kh_end(bitmap_git.bitmaps)) {
 517                                struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, pos);
 518                                struct ewah_bitmap *or_with = lookup_stored_bitmap(st);
 519
 520                                if (base == NULL)
 521                                        base = ewah_to_bitmap(or_with);
 522                                else
 523                                        bitmap_or_ewah(base, or_with);
 524
 525                                object->flags |= SEEN;
 526                                continue;
 527                        }
 528                }
 529
 530                object_list_insert(object, &not_mapped);
 531        }
 532
 533        /*
 534         * Best case scenario: We found bitmaps for all the roots,
 535         * so the resulting `or` bitmap has the full reachability analysis
 536         */
 537        if (not_mapped == NULL)
 538                return base;
 539
 540        roots = not_mapped;
 541
 542        /*
 543         * Let's iterate through all the roots that don't have bitmaps to
 544         * check if we can determine them to be reachable from the existing
 545         * global bitmap.
 546         *
 547         * If we cannot find them in the existing global bitmap, we'll need
 548         * to push them to an actual walk and run it until we can confirm
 549         * they are reachable
 550         */
 551        while (roots) {
 552                struct object *object = roots->item;
 553                int pos;
 554
 555                roots = roots->next;
 556                pos = bitmap_position(object->sha1);
 557
 558                if (pos < 0 || base == NULL || !bitmap_get(base, pos)) {
 559                        object->flags &= ~UNINTERESTING;
 560                        add_pending_object(revs, object, "");
 561                        needs_walk = 1;
 562                } else {
 563                        object->flags |= SEEN;
 564                }
 565        }
 566
 567        if (needs_walk) {
 568                struct include_data incdata;
 569
 570                if (base == NULL)
 571                        base = bitmap_new();
 572
 573                incdata.base = base;
 574                incdata.seen = seen;
 575
 576                revs->include_check = should_include;
 577                revs->include_check_data = &incdata;
 578
 579                if (prepare_revision_walk(revs))
 580                        die("revision walk setup failed");
 581
 582                traverse_commit_list(revs, show_commit, show_object, base);
 583        }
 584
 585        return base;
 586}
 587
 588static void show_extended_objects(struct bitmap *objects,
 589                                  show_reachable_fn show_reach)
 590{
 591        struct eindex *eindex = &bitmap_git.ext_index;
 592        uint32_t i;
 593
 594        for (i = 0; i < eindex->count; ++i) {
 595                struct object *obj;
 596
 597                if (!bitmap_get(objects, bitmap_git.pack->num_objects + i))
 598                        continue;
 599
 600                obj = eindex->objects[i];
 601                show_reach(obj->sha1, obj->type, 0, eindex->hashes[i], NULL, 0);
 602        }
 603}
 604
 605static void show_objects_for_type(
 606        struct bitmap *objects,
 607        struct ewah_bitmap *type_filter,
 608        enum object_type object_type,
 609        show_reachable_fn show_reach)
 610{
 611        size_t pos = 0, i = 0;
 612        uint32_t offset;
 613
 614        struct ewah_iterator it;
 615        eword_t filter;
 616
 617        if (bitmap_git.reuse_objects == bitmap_git.pack->num_objects)
 618                return;
 619
 620        ewah_iterator_init(&it, type_filter);
 621
 622        while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) {
 623                eword_t word = objects->words[i] & filter;
 624
 625                for (offset = 0; offset < BITS_IN_WORD; ++offset) {
 626                        const unsigned char *sha1;
 627                        struct revindex_entry *entry;
 628                        uint32_t hash = 0;
 629
 630                        if ((word >> offset) == 0)
 631                                break;
 632
 633                        offset += ewah_bit_ctz64(word >> offset);
 634
 635                        if (pos + offset < bitmap_git.reuse_objects)
 636                                continue;
 637
 638                        entry = &bitmap_git.reverse_index->revindex[pos + offset];
 639                        sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
 640
 641                        if (bitmap_git.hashes)
 642                                hash = ntohl(bitmap_git.hashes[entry->nr]);
 643
 644                        show_reach(sha1, object_type, 0, hash, bitmap_git.pack, entry->offset);
 645                }
 646
 647                pos += BITS_IN_WORD;
 648                i++;
 649        }
 650}
 651
 652static int in_bitmapped_pack(struct object_list *roots)
 653{
 654        while (roots) {
 655                struct object *object = roots->item;
 656                roots = roots->next;
 657
 658                if (find_pack_entry_one(object->sha1, bitmap_git.pack) > 0)
 659                        return 1;
 660        }
 661
 662        return 0;
 663}
 664
 665int prepare_bitmap_walk(struct rev_info *revs)
 666{
 667        unsigned int i;
 668        unsigned int pending_nr = revs->pending.nr;
 669        struct object_array_entry *pending_e = revs->pending.objects;
 670
 671        struct object_list *wants = NULL;
 672        struct object_list *haves = NULL;
 673
 674        struct bitmap *wants_bitmap = NULL;
 675        struct bitmap *haves_bitmap = NULL;
 676
 677        if (!bitmap_git.loaded) {
 678                /* try to open a bitmapped pack, but don't parse it yet
 679                 * because we may not need to use it */
 680                if (open_pack_bitmap() < 0)
 681                        return -1;
 682        }
 683
 684        for (i = 0; i < pending_nr; ++i) {
 685                struct object *object = pending_e[i].item;
 686
 687                if (object->type == OBJ_NONE)
 688                        parse_object_or_die(object->sha1, NULL);
 689
 690                while (object->type == OBJ_TAG) {
 691                        struct tag *tag = (struct tag *) object;
 692
 693                        if (object->flags & UNINTERESTING)
 694                                object_list_insert(object, &haves);
 695                        else
 696                                object_list_insert(object, &wants);
 697
 698                        if (!tag->tagged)
 699                                die("bad tag");
 700                        object = parse_object_or_die(tag->tagged->sha1, NULL);
 701                }
 702
 703                if (object->flags & UNINTERESTING)
 704                        object_list_insert(object, &haves);
 705                else
 706                        object_list_insert(object, &wants);
 707        }
 708
 709        /*
 710         * if we have a HAVES list, but none of those haves is contained
 711         * in the packfile that has a bitmap, we don't have anything to
 712         * optimize here
 713         */
 714        if (haves && !in_bitmapped_pack(haves))
 715                return -1;
 716
 717        /* if we don't want anything, we're done here */
 718        if (!wants)
 719                return -1;
 720
 721        /*
 722         * now we're going to use bitmaps, so load the actual bitmap entries
 723         * from disk. this is the point of no return; after this the rev_list
 724         * becomes invalidated and we must perform the revwalk through bitmaps
 725         */
 726        if (!bitmap_git.loaded && load_pack_bitmap() < 0)
 727                return -1;
 728
 729        revs->pending.nr = 0;
 730        revs->pending.alloc = 0;
 731        revs->pending.objects = NULL;
 732
 733        if (haves) {
 734                revs->ignore_missing_links = 1;
 735                haves_bitmap = find_objects(revs, haves, NULL);
 736                reset_revision_walk();
 737                revs->ignore_missing_links = 0;
 738
 739                if (haves_bitmap == NULL)
 740                        die("BUG: failed to perform bitmap walk");
 741        }
 742
 743        wants_bitmap = find_objects(revs, wants, haves_bitmap);
 744
 745        if (!wants_bitmap)
 746                die("BUG: failed to perform bitmap walk");
 747
 748        if (haves_bitmap)
 749                bitmap_and_not(wants_bitmap, haves_bitmap);
 750
 751        bitmap_git.result = wants_bitmap;
 752
 753        bitmap_free(haves_bitmap);
 754        return 0;
 755}
 756
 757int reuse_partial_packfile_from_bitmap(struct packed_git **packfile,
 758                                       uint32_t *entries,
 759                                       off_t *up_to)
 760{
 761        /*
 762         * Reuse the packfile content if we need more than
 763         * 90% of its objects
 764         */
 765        static const double REUSE_PERCENT = 0.9;
 766
 767        struct bitmap *result = bitmap_git.result;
 768        uint32_t reuse_threshold;
 769        uint32_t i, reuse_objects = 0;
 770
 771        assert(result);
 772
 773        for (i = 0; i < result->word_alloc; ++i) {
 774                if (result->words[i] != (eword_t)~0) {
 775                        reuse_objects += ewah_bit_ctz64(~result->words[i]);
 776                        break;
 777                }
 778
 779                reuse_objects += BITS_IN_WORD;
 780        }
 781
 782#ifdef GIT_BITMAP_DEBUG
 783        {
 784                const unsigned char *sha1;
 785                struct revindex_entry *entry;
 786
 787                entry = &bitmap_git.reverse_index->revindex[reuse_objects];
 788                sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
 789
 790                fprintf(stderr, "Failed to reuse at %d (%016llx)\n",
 791                        reuse_objects, result->words[i]);
 792                fprintf(stderr, " %s\n", sha1_to_hex(sha1));
 793        }
 794#endif
 795
 796        if (!reuse_objects)
 797                return -1;
 798
 799        if (reuse_objects >= bitmap_git.pack->num_objects) {
 800                bitmap_git.reuse_objects = *entries = bitmap_git.pack->num_objects;
 801                *up_to = -1; /* reuse the full pack */
 802                *packfile = bitmap_git.pack;
 803                return 0;
 804        }
 805
 806        reuse_threshold = bitmap_popcount(bitmap_git.result) * REUSE_PERCENT;
 807
 808        if (reuse_objects < reuse_threshold)
 809                return -1;
 810
 811        bitmap_git.reuse_objects = *entries = reuse_objects;
 812        *up_to = bitmap_git.reverse_index->revindex[reuse_objects].offset;
 813        *packfile = bitmap_git.pack;
 814
 815        return 0;
 816}
 817
 818void traverse_bitmap_commit_list(show_reachable_fn show_reachable)
 819{
 820        assert(bitmap_git.result);
 821
 822        show_objects_for_type(bitmap_git.result, bitmap_git.commits,
 823                OBJ_COMMIT, show_reachable);
 824        show_objects_for_type(bitmap_git.result, bitmap_git.trees,
 825                OBJ_TREE, show_reachable);
 826        show_objects_for_type(bitmap_git.result, bitmap_git.blobs,
 827                OBJ_BLOB, show_reachable);
 828        show_objects_for_type(bitmap_git.result, bitmap_git.tags,
 829                OBJ_TAG, show_reachable);
 830
 831        show_extended_objects(bitmap_git.result, show_reachable);
 832
 833        bitmap_free(bitmap_git.result);
 834        bitmap_git.result = NULL;
 835}
 836
 837static uint32_t count_object_type(struct bitmap *objects,
 838                                  enum object_type type)
 839{
 840        struct eindex *eindex = &bitmap_git.ext_index;
 841
 842        uint32_t i = 0, count = 0;
 843        struct ewah_iterator it;
 844        eword_t filter;
 845
 846        switch (type) {
 847        case OBJ_COMMIT:
 848                ewah_iterator_init(&it, bitmap_git.commits);
 849                break;
 850
 851        case OBJ_TREE:
 852                ewah_iterator_init(&it, bitmap_git.trees);
 853                break;
 854
 855        case OBJ_BLOB:
 856                ewah_iterator_init(&it, bitmap_git.blobs);
 857                break;
 858
 859        case OBJ_TAG:
 860                ewah_iterator_init(&it, bitmap_git.tags);
 861                break;
 862
 863        default:
 864                return 0;
 865        }
 866
 867        while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) {
 868                eword_t word = objects->words[i++] & filter;
 869                count += ewah_bit_popcount64(word);
 870        }
 871
 872        for (i = 0; i < eindex->count; ++i) {
 873                if (eindex->objects[i]->type == type &&
 874                        bitmap_get(objects, bitmap_git.pack->num_objects + i))
 875                        count++;
 876        }
 877
 878        return count;
 879}
 880
 881void count_bitmap_commit_list(uint32_t *commits, uint32_t *trees,
 882                              uint32_t *blobs, uint32_t *tags)
 883{
 884        assert(bitmap_git.result);
 885
 886        if (commits)
 887                *commits = count_object_type(bitmap_git.result, OBJ_COMMIT);
 888
 889        if (trees)
 890                *trees = count_object_type(bitmap_git.result, OBJ_TREE);
 891
 892        if (blobs)
 893                *blobs = count_object_type(bitmap_git.result, OBJ_BLOB);
 894
 895        if (tags)
 896                *tags = count_object_type(bitmap_git.result, OBJ_TAG);
 897}
 898
 899struct bitmap_test_data {
 900        struct bitmap *base;
 901        struct progress *prg;
 902        size_t seen;
 903};
 904
 905static void test_show_object(struct object *object,
 906                             const struct name_path *path,
 907                             const char *last, void *data)
 908{
 909        struct bitmap_test_data *tdata = data;
 910        int bitmap_pos;
 911
 912        bitmap_pos = bitmap_position(object->sha1);
 913        if (bitmap_pos < 0)
 914                die("Object not in bitmap: %s\n", sha1_to_hex(object->sha1));
 915
 916        bitmap_set(tdata->base, bitmap_pos);
 917        display_progress(tdata->prg, ++tdata->seen);
 918}
 919
 920static void test_show_commit(struct commit *commit, void *data)
 921{
 922        struct bitmap_test_data *tdata = data;
 923        int bitmap_pos;
 924
 925        bitmap_pos = bitmap_position(commit->object.sha1);
 926        if (bitmap_pos < 0)
 927                die("Object not in bitmap: %s\n", sha1_to_hex(commit->object.sha1));
 928
 929        bitmap_set(tdata->base, bitmap_pos);
 930        display_progress(tdata->prg, ++tdata->seen);
 931}
 932
 933void test_bitmap_walk(struct rev_info *revs)
 934{
 935        struct object *root;
 936        struct bitmap *result = NULL;
 937        khiter_t pos;
 938        size_t result_popcnt;
 939        struct bitmap_test_data tdata;
 940
 941        if (prepare_bitmap_git())
 942                die("failed to load bitmap indexes");
 943
 944        if (revs->pending.nr != 1)
 945                die("you must specify exactly one commit to test");
 946
 947        fprintf(stderr, "Bitmap v%d test (%d entries loaded)\n",
 948                bitmap_git.version, bitmap_git.entry_count);
 949
 950        root = revs->pending.objects[0].item;
 951        pos = kh_get_sha1(bitmap_git.bitmaps, root->sha1);
 952
 953        if (pos < kh_end(bitmap_git.bitmaps)) {
 954                struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, pos);
 955                struct ewah_bitmap *bm = lookup_stored_bitmap(st);
 956
 957                fprintf(stderr, "Found bitmap for %s. %d bits / %08x checksum\n",
 958                        sha1_to_hex(root->sha1), (int)bm->bit_size, ewah_checksum(bm));
 959
 960                result = ewah_to_bitmap(bm);
 961        }
 962
 963        if (result == NULL)
 964                die("Commit %s doesn't have an indexed bitmap", sha1_to_hex(root->sha1));
 965
 966        revs->tag_objects = 1;
 967        revs->tree_objects = 1;
 968        revs->blob_objects = 1;
 969
 970        result_popcnt = bitmap_popcount(result);
 971
 972        if (prepare_revision_walk(revs))
 973                die("revision walk setup failed");
 974
 975        tdata.base = bitmap_new();
 976        tdata.prg = start_progress("Verifying bitmap entries", result_popcnt);
 977        tdata.seen = 0;
 978
 979        traverse_commit_list(revs, &test_show_commit, &test_show_object, &tdata);
 980
 981        stop_progress(&tdata.prg);
 982
 983        if (bitmap_equals(result, tdata.base))
 984                fprintf(stderr, "OK!\n");
 985        else
 986                fprintf(stderr, "Mismatch!\n");
 987
 988        free(result);
 989}
 990
 991static int rebuild_bitmap(uint32_t *reposition,
 992                          struct ewah_bitmap *source,
 993                          struct bitmap *dest)
 994{
 995        uint32_t pos = 0;
 996        struct ewah_iterator it;
 997        eword_t word;
 998
 999        ewah_iterator_init(&it, source);
1000
1001        while (ewah_iterator_next(&word, &it)) {
1002                uint32_t offset, bit_pos;
1003
1004                for (offset = 0; offset < BITS_IN_WORD; ++offset) {
1005                        if ((word >> offset) == 0)
1006                                break;
1007
1008                        offset += ewah_bit_ctz64(word >> offset);
1009
1010                        bit_pos = reposition[pos + offset];
1011                        if (bit_pos > 0)
1012                                bitmap_set(dest, bit_pos - 1);
1013                        else /* can't reuse, we don't have the object */
1014                                return -1;
1015                }
1016
1017                pos += BITS_IN_WORD;
1018        }
1019        return 0;
1020}
1021
1022int rebuild_existing_bitmaps(struct packing_data *mapping,
1023                             khash_sha1 *reused_bitmaps,
1024                             int show_progress)
1025{
1026        uint32_t i, num_objects;
1027        uint32_t *reposition;
1028        struct bitmap *rebuild;
1029        struct stored_bitmap *stored;
1030        struct progress *progress = NULL;
1031
1032        khiter_t hash_pos;
1033        int hash_ret;
1034
1035        if (prepare_bitmap_git() < 0)
1036                return -1;
1037
1038        num_objects = bitmap_git.pack->num_objects;
1039        reposition = xcalloc(num_objects, sizeof(uint32_t));
1040
1041        for (i = 0; i < num_objects; ++i) {
1042                const unsigned char *sha1;
1043                struct revindex_entry *entry;
1044                struct object_entry *oe;
1045
1046                entry = &bitmap_git.reverse_index->revindex[i];
1047                sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
1048                oe = packlist_find(mapping, sha1, NULL);
1049
1050                if (oe)
1051                        reposition[i] = oe->in_pack_pos + 1;
1052        }
1053
1054        rebuild = bitmap_new();
1055        i = 0;
1056
1057        if (show_progress)
1058                progress = start_progress("Reusing bitmaps", 0);
1059
1060        kh_foreach_value(bitmap_git.bitmaps, stored, {
1061                if (stored->flags & BITMAP_FLAG_REUSE) {
1062                        if (!rebuild_bitmap(reposition,
1063                                            lookup_stored_bitmap(stored),
1064                                            rebuild)) {
1065                                hash_pos = kh_put_sha1(reused_bitmaps,
1066                                                       stored->sha1,
1067                                                       &hash_ret);
1068                                kh_value(reused_bitmaps, hash_pos) =
1069                                        bitmap_to_ewah(rebuild);
1070                        }
1071                        bitmap_reset(rebuild);
1072                        display_progress(progress, ++i);
1073                }
1074        });
1075
1076        stop_progress(&progress);
1077
1078        free(reposition);
1079        bitmap_free(rebuild);
1080        return 0;
1081}