git.oblomov.eu Git - git/blob - midx.c

   1 #include "cache.h"
   2 #include "config.h"
   3 #include "csum-file.h"
   4 #include "dir.h"
   5 #include "lockfile.h"
   6 #include "packfile.h"
   7 #include "object-store.h"
   8 #include "sha1-lookup.h"
   9 #include "midx.h"
  10 #include "progress.h"
  11 #include "trace2.h"
  12 #include "run-command.h"
  13
  14 #define MIDX_SIGNATURE 0x4d494458 /* "MIDX" */
  15 #define MIDX_VERSION 1
  16 #define MIDX_BYTE_FILE_VERSION 4
  17 #define MIDX_BYTE_HASH_VERSION 5
  18 #define MIDX_BYTE_NUM_CHUNKS 6
  19 #define MIDX_BYTE_NUM_PACKS 8
  20 #define MIDX_HASH_VERSION 1
  21 #define MIDX_HEADER_SIZE 12
  22 #define MIDX_MIN_SIZE (MIDX_HEADER_SIZE + the_hash_algo->rawsz)
  23
  24 #define MIDX_MAX_CHUNKS 5
  25 #define MIDX_CHUNK_ALIGNMENT 4
  26 #define MIDX_CHUNKID_PACKNAMES 0x504e414d /* "PNAM" */
  27 #define MIDX_CHUNKID_OIDFANOUT 0x4f494446 /* "OIDF" */
  28 #define MIDX_CHUNKID_OIDLOOKUP 0x4f49444c /* "OIDL" */
  29 #define MIDX_CHUNKID_OBJECTOFFSETS 0x4f4f4646 /* "OOFF" */
  30 #define MIDX_CHUNKID_LARGEOFFSETS 0x4c4f4646 /* "LOFF" */
  31 #define MIDX_CHUNKLOOKUP_WIDTH (sizeof(uint32_t) + sizeof(uint64_t))
  32 #define MIDX_CHUNK_FANOUT_SIZE (sizeof(uint32_t) * 256)
  33 #define MIDX_CHUNK_OFFSET_WIDTH (2 * sizeof(uint32_t))
  34 #define MIDX_CHUNK_LARGE_OFFSET_WIDTH (sizeof(uint64_t))
  35 #define MIDX_LARGE_OFFSET_NEEDED 0x80000000
  36
  37 #define PACK_EXPIRED UINT_MAX
  38
  39 static char *get_midx_filename(const char *object_dir)
  40 {
  41         return xstrfmt("%s/pack/multi-pack-index", object_dir);
  42 }
  43
  44 struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local)
  45 {
  46         struct multi_pack_index *m = NULL;
  47         int fd;
  48         struct stat st;
  49         size_t midx_size;
  50         void *midx_map = NULL;
  51         uint32_t hash_version;
  52         char *midx_name = get_midx_filename(object_dir);
  53         uint32_t i;
  54         const char *cur_pack_name;
  55
  56         fd = git_open(midx_name);
  57
  58         if (fd < 0)
  59                 goto cleanup_fail;
  60         if (fstat(fd, &st)) {
  61                 error_errno(_("failed to read %s"), midx_name);
  62                 goto cleanup_fail;
  63         }
  64
  65         midx_size = xsize_t(st.st_size);
  66
  67         if (midx_size < MIDX_MIN_SIZE) {
  68                 error(_("multi-pack-index file %s is too small"), midx_name);
  69                 goto cleanup_fail;
  70         }
  71
  72         FREE_AND_NULL(midx_name);
  73
  74         midx_map = xmmap(NULL, midx_size, PROT_READ, MAP_PRIVATE, fd, 0);
  75
  76         FLEX_ALLOC_STR(m, object_dir, object_dir);
  77         m->fd = fd;
  78         m->data = midx_map;
  79         m->data_len = midx_size;
  80         m->local = local;
  81
  82         m->signature = get_be32(m->data);
  83         if (m->signature != MIDX_SIGNATURE)
  84                 die(_("multi-pack-index signature 0x%08x does not match signature 0x%08x"),
  85                       m->signature, MIDX_SIGNATURE);
  86
  87         m->version = m->data[MIDX_BYTE_FILE_VERSION];
  88         if (m->version != MIDX_VERSION)
  89                 die(_("multi-pack-index version %d not recognized"),
  90                       m->version);
  91
  92         hash_version = m->data[MIDX_BYTE_HASH_VERSION];
  93         if (hash_version != MIDX_HASH_VERSION)
  94                 die(_("hash version %u does not match"), hash_version);
  95         m->hash_len = the_hash_algo->rawsz;
  96
  97         m->num_chunks = m->data[MIDX_BYTE_NUM_CHUNKS];
  98
  99         m->num_packs = get_be32(m->data + MIDX_BYTE_NUM_PACKS);
 100
 101         for (i = 0; i < m->num_chunks; i++) {
 102                 uint32_t chunk_id = get_be32(m->data + MIDX_HEADER_SIZE +
 103                                              MIDX_CHUNKLOOKUP_WIDTH * i);
 104                 uint64_t chunk_offset = get_be64(m->data + MIDX_HEADER_SIZE + 4 +
 105                                                  MIDX_CHUNKLOOKUP_WIDTH * i);
 106
 107                 if (chunk_offset >= m->data_len)
 108                         die(_("invalid chunk offset (too large)"));
 109
 110                 switch (chunk_id) {
 111                         case MIDX_CHUNKID_PACKNAMES:
 112                                 m->chunk_pack_names = m->data + chunk_offset;
 113                                 break;
 114
 115                         case MIDX_CHUNKID_OIDFANOUT:
 116                                 m->chunk_oid_fanout = (uint32_t *)(m->data + chunk_offset);
 117                                 break;
 118
 119                         case MIDX_CHUNKID_OIDLOOKUP:
 120                                 m->chunk_oid_lookup = m->data + chunk_offset;
 121                                 break;
 122
 123                         case MIDX_CHUNKID_OBJECTOFFSETS:
 124                                 m->chunk_object_offsets = m->data + chunk_offset;
 125                                 break;
 126
 127                         case MIDX_CHUNKID_LARGEOFFSETS:
 128                                 m->chunk_large_offsets = m->data + chunk_offset;
 129                                 break;
 130
 131                         case 0:
 132                                 die(_("terminating multi-pack-index chunk id appears earlier than expected"));
 133                                 break;
 134
 135                         default:
 136                                 /*
 137                                  * Do nothing on unrecognized chunks, allowing future
 138                                  * extensions to add optional chunks.
 139                                  */
 140                                 break;
 141                 }
 142         }
 143
 144         if (!m->chunk_pack_names)
 145                 die(_("multi-pack-index missing required pack-name chunk"));
 146         if (!m->chunk_oid_fanout)
 147                 die(_("multi-pack-index missing required OID fanout chunk"));
 148         if (!m->chunk_oid_lookup)
 149                 die(_("multi-pack-index missing required OID lookup chunk"));
 150         if (!m->chunk_object_offsets)
 151                 die(_("multi-pack-index missing required object offsets chunk"));
 152
 153         m->num_objects = ntohl(m->chunk_oid_fanout[255]);
 154
 155         m->pack_names = xcalloc(m->num_packs, sizeof(*m->pack_names));
 156         m->packs = xcalloc(m->num_packs, sizeof(*m->packs));
 157
 158         cur_pack_name = (const char *)m->chunk_pack_names;
 159         for (i = 0; i < m->num_packs; i++) {
 160                 m->pack_names[i] = cur_pack_name;
 161
 162                 cur_pack_name += strlen(cur_pack_name) + 1;
 163
 164                 if (i && strcmp(m->pack_names[i], m->pack_names[i - 1]) <= 0)
 165                         die(_("multi-pack-index pack names out of order: '%s' before '%s'"),
 166                               m->pack_names[i - 1],
 167                               m->pack_names[i]);
 168         }
 169
 170         trace2_data_intmax("midx", the_repository, "load/num_packs", m->num_packs);
 171         trace2_data_intmax("midx", the_repository, "load/num_objects", m->num_objects);
 172
 173         return m;
 174
 175 cleanup_fail:
 176         free(m);
 177         free(midx_name);
 178         if (midx_map)
 179                 munmap(midx_map, midx_size);
 180         if (0 <= fd)
 181                 close(fd);
 182         return NULL;
 183 }
 184
 185 void close_midx(struct multi_pack_index *m)
 186 {
 187         uint32_t i;
 188
 189         if (!m)
 190                 return;
 191
 192         munmap((unsigned char *)m->data, m->data_len);
 193         close(m->fd);
 194         m->fd = -1;
 195
 196         for (i = 0; i < m->num_packs; i++) {
 197                 if (m->packs[i])
 198                         m->packs[i]->multi_pack_index = 0;
 199         }
 200         FREE_AND_NULL(m->packs);
 201         FREE_AND_NULL(m->pack_names);
 202 }
 203
 204 int prepare_midx_pack(struct repository *r, struct multi_pack_index *m, uint32_t pack_int_id)
 205 {
 206         struct strbuf pack_name = STRBUF_INIT;
 207         struct packed_git *p;
 208
 209         if (pack_int_id >= m->num_packs)
 210                 die(_("bad pack-int-id: %u (%u total packs)"),
 211                     pack_int_id, m->num_packs);
 212
 213         if (m->packs[pack_int_id])
 214                 return 0;
 215
 216         strbuf_addf(&pack_name, "%s/pack/%s", m->object_dir,
 217                     m->pack_names[pack_int_id]);
 218
 219         p = add_packed_git(pack_name.buf, pack_name.len, m->local);
 220         strbuf_release(&pack_name);
 221
 222         if (!p)
 223                 return 1;
 224
 225         p->multi_pack_index = 1;
 226         m->packs[pack_int_id] = p;
 227         install_packed_git(r, p);
 228         list_add_tail(&p->mru, &r->objects->packed_git_mru);
 229
 230         return 0;
 231 }
 232
 233 int bsearch_midx(const struct object_id *oid, struct multi_pack_index *m, uint32_t *result)
 234 {
 235         return bsearch_hash(oid->hash, m->chunk_oid_fanout, m->chunk_oid_lookup,
 236                             the_hash_algo->rawsz, result);
 237 }
 238
 239 struct object_id *nth_midxed_object_oid(struct object_id *oid,
 240                                         struct multi_pack_index *m,
 241                                         uint32_t n)
 242 {
 243         if (n >= m->num_objects)
 244                 return NULL;
 245
 246         hashcpy(oid->hash, m->chunk_oid_lookup + m->hash_len * n);
 247         return oid;
 248 }
 249
 250 static off_t nth_midxed_offset(struct multi_pack_index *m, uint32_t pos)
 251 {
 252         const unsigned char *offset_data;
 253         uint32_t offset32;
 254
 255         offset_data = m->chunk_object_offsets + pos * MIDX_CHUNK_OFFSET_WIDTH;
 256         offset32 = get_be32(offset_data + sizeof(uint32_t));
 257
 258         if (m->chunk_large_offsets && offset32 & MIDX_LARGE_OFFSET_NEEDED) {
 259                 if (sizeof(off_t) < sizeof(uint64_t))
 260                         die(_("multi-pack-index stores a 64-bit offset, but off_t is too small"));
 261
 262                 offset32 ^= MIDX_LARGE_OFFSET_NEEDED;
 263                 return get_be64(m->chunk_large_offsets + sizeof(uint64_t) * offset32);
 264         }
 265
 266         return offset32;
 267 }
 268
 269 static uint32_t nth_midxed_pack_int_id(struct multi_pack_index *m, uint32_t pos)
 270 {
 271         return get_be32(m->chunk_object_offsets + pos * MIDX_CHUNK_OFFSET_WIDTH);
 272 }
 273
 274 static int nth_midxed_pack_entry(struct repository *r,
 275                                  struct multi_pack_index *m,
 276                                  struct pack_entry *e,
 277                                  uint32_t pos)
 278 {
 279         uint32_t pack_int_id;
 280         struct packed_git *p;
 281
 282         if (pos >= m->num_objects)
 283                 return 0;
 284
 285         pack_int_id = nth_midxed_pack_int_id(m, pos);
 286
 287         if (prepare_midx_pack(r, m, pack_int_id))
 288                 die(_("error preparing packfile from multi-pack-index"));
 289         p = m->packs[pack_int_id];
 290
 291         /*
 292         * We are about to tell the caller where they can locate the
 293         * requested object.  We better make sure the packfile is
 294         * still here and can be accessed before supplying that
 295         * answer, as it may have been deleted since the MIDX was
 296         * loaded!
 297         */
 298         if (!is_pack_valid(p))
 299                 return 0;
 300
 301         if (p->num_bad_objects) {
 302                 uint32_t i;
 303                 struct object_id oid;
 304                 nth_midxed_object_oid(&oid, m, pos);
 305                 for (i = 0; i < p->num_bad_objects; i++)
 306                         if (hasheq(oid.hash,
 307                                    p->bad_object_sha1 + the_hash_algo->rawsz * i))
 308                                 return 0;
 309         }
 310
 311         e->offset = nth_midxed_offset(m, pos);
 312         e->p = p;
 313
 314         return 1;
 315 }
 316
 317 int fill_midx_entry(struct repository * r,
 318                     const struct object_id *oid,
 319                     struct pack_entry *e,
 320                     struct multi_pack_index *m)
 321 {
 322         uint32_t pos;
 323
 324         if (!bsearch_midx(oid, m, &pos))
 325                 return 0;
 326
 327         return nth_midxed_pack_entry(r, m, e, pos);
 328 }
 329
 330 /* Match "foo.idx" against either "foo.pack" _or_ "foo.idx". */
 331 static int cmp_idx_or_pack_name(const char *idx_or_pack_name,
 332                                 const char *idx_name)
 333 {
 334         /* Skip past any initial matching prefix. */
 335         while (*idx_name && *idx_name == *idx_or_pack_name) {
 336                 idx_name++;
 337                 idx_or_pack_name++;
 338         }
 339
 340         /*
 341          * If we didn't match completely, we may have matched "pack-1234." and
 342          * be left with "idx" and "pack" respectively, which is also OK. We do
 343          * not have to check for "idx" and "idx", because that would have been
 344          * a complete match (and in that case these strcmps will be false, but
 345          * we'll correctly return 0 from the final strcmp() below.
 346          *
 347          * Technically this matches "fooidx" and "foopack", but we'd never have
 348          * such names in the first place.
 349          */
 350         if (!strcmp(idx_name, "idx") && !strcmp(idx_or_pack_name, "pack"))
 351                 return 0;
 352
 353         /*
 354          * This not only checks for a complete match, but also orders based on
 355          * the first non-identical character, which means our ordering will
 356          * match a raw strcmp(). That makes it OK to use this to binary search
 357          * a naively-sorted list.
 358          */
 359         return strcmp(idx_or_pack_name, idx_name);
 360 }
 361
 362 int midx_contains_pack(struct multi_pack_index *m, const char *idx_or_pack_name)
 363 {
 364         uint32_t first = 0, last = m->num_packs;
 365
 366         while (first < last) {
 367                 uint32_t mid = first + (last - first) / 2;
 368                 const char *current;
 369                 int cmp;
 370
 371                 current = m->pack_names[mid];
 372                 cmp = cmp_idx_or_pack_name(idx_or_pack_name, current);
 373                 if (!cmp)
 374                         return 1;
 375                 if (cmp > 0) {
 376                         first = mid + 1;
 377                         continue;
 378                 }
 379                 last = mid;
 380         }
 381
 382         return 0;
 383 }
 384
 385 int prepare_multi_pack_index_one(struct repository *r, const char *object_dir, int local)
 386 {
 387         struct multi_pack_index *m;
 388         struct multi_pack_index *m_search;
 389         int config_value;
 390         static int env_value = -1;
 391
 392         if (env_value < 0)
 393                 env_value = git_env_bool(GIT_TEST_MULTI_PACK_INDEX, 0);
 394
 395         if (!env_value &&
 396             (repo_config_get_bool(r, "core.multipackindex", &config_value) ||
 397             !config_value))
 398                 return 0;
 399
 400         for (m_search = r->objects->multi_pack_index; m_search; m_search = m_search->next)
 401                 if (!strcmp(object_dir, m_search->object_dir))
 402                         return 1;
 403
 404         m = load_multi_pack_index(object_dir, local);
 405
 406         if (m) {
 407                 m->next = r->objects->multi_pack_index;
 408                 r->objects->multi_pack_index = m;
 409                 return 1;
 410         }
 411
 412         return 0;
 413 }
 414
 415 static size_t write_midx_header(struct hashfile *f,
 416                                 unsigned char num_chunks,
 417                                 uint32_t num_packs)
 418 {
 419         unsigned char byte_values[4];
 420
 421         hashwrite_be32(f, MIDX_SIGNATURE);
 422         byte_values[0] = MIDX_VERSION;
 423         byte_values[1] = MIDX_HASH_VERSION;
 424         byte_values[2] = num_chunks;
 425         byte_values[3] = 0; /* unused */
 426         hashwrite(f, byte_values, sizeof(byte_values));
 427         hashwrite_be32(f, num_packs);
 428
 429         return MIDX_HEADER_SIZE;
 430 }
 431
 432 struct pack_info {
 433         uint32_t orig_pack_int_id;
 434         char *pack_name;
 435         struct packed_git *p;
 436         unsigned expired : 1;
 437 };
 438
 439 static int pack_info_compare(const void *_a, const void *_b)
 440 {
 441         struct pack_info *a = (struct pack_info *)_a;
 442         struct pack_info *b = (struct pack_info *)_b;
 443         return strcmp(a->pack_name, b->pack_name);
 444 }
 445
 446 struct pack_list {
 447         struct pack_info *info;
 448         uint32_t nr;
 449         uint32_t alloc;
 450         struct multi_pack_index *m;
 451 };
 452
 453 static void add_pack_to_midx(const char *full_path, size_t full_path_len,
 454                              const char *file_name, void *data)
 455 {
 456         struct pack_list *packs = (struct pack_list *)data;
 457
 458         if (ends_with(file_name, ".idx")) {
 459                 if (packs->m && midx_contains_pack(packs->m, file_name))
 460                         return;
 461
 462                 ALLOC_GROW(packs->info, packs->nr + 1, packs->alloc);
 463
 464                 packs->info[packs->nr].p = add_packed_git(full_path,
 465                                                           full_path_len,
 466                                                           0);
 467
 468                 if (!packs->info[packs->nr].p) {
 469                         warning(_("failed to add packfile '%s'"),
 470                                 full_path);
 471                         return;
 472                 }
 473
 474                 if (open_pack_index(packs->info[packs->nr].p)) {
 475                         warning(_("failed to open pack-index '%s'"),
 476                                 full_path);
 477                         close_pack(packs->info[packs->nr].p);
 478                         FREE_AND_NULL(packs->info[packs->nr].p);
 479                         return;
 480                 }
 481
 482                 packs->info[packs->nr].pack_name = xstrdup(file_name);
 483                 packs->info[packs->nr].orig_pack_int_id = packs->nr;
 484                 packs->info[packs->nr].expired = 0;
 485                 packs->nr++;
 486         }
 487 }
 488
 489 struct pack_midx_entry {
 490         struct object_id oid;
 491         uint32_t pack_int_id;
 492         time_t pack_mtime;
 493         uint64_t offset;
 494 };
 495
 496 static int midx_oid_compare(const void *_a, const void *_b)
 497 {
 498         const struct pack_midx_entry *a = (const struct pack_midx_entry *)_a;
 499         const struct pack_midx_entry *b = (const struct pack_midx_entry *)_b;
 500         int cmp = oidcmp(&a->oid, &b->oid);
 501
 502         if (cmp)
 503                 return cmp;
 504
 505         if (a->pack_mtime > b->pack_mtime)
 506                 return -1;
 507         else if (a->pack_mtime < b->pack_mtime)
 508                 return 1;
 509
 510         return a->pack_int_id - b->pack_int_id;
 511 }
 512
 513 static int nth_midxed_pack_midx_entry(struct multi_pack_index *m,
 514                                       struct pack_midx_entry *e,
 515                                       uint32_t pos)
 516 {
 517         if (pos >= m->num_objects)
 518                 return 1;
 519
 520         nth_midxed_object_oid(&e->oid, m, pos);
 521         e->pack_int_id = nth_midxed_pack_int_id(m, pos);
 522         e->offset = nth_midxed_offset(m, pos);
 523
 524         /* consider objects in midx to be from "old" packs */
 525         e->pack_mtime = 0;
 526         return 0;
 527 }
 528
 529 static void fill_pack_entry(uint32_t pack_int_id,
 530                             struct packed_git *p,
 531                             uint32_t cur_object,
 532                             struct pack_midx_entry *entry)
 533 {
 534         if (!nth_packed_object_oid(&entry->oid, p, cur_object))
 535                 die(_("failed to locate object %d in packfile"), cur_object);
 536
 537         entry->pack_int_id = pack_int_id;
 538         entry->pack_mtime = p->mtime;
 539
 540         entry->offset = nth_packed_object_offset(p, cur_object);
 541 }
 542
 543 /*
 544  * It is possible to artificially get into a state where there are many
 545  * duplicate copies of objects. That can create high memory pressure if
 546  * we are to create a list of all objects before de-duplication. To reduce
 547  * this memory pressure without a significant performance drop, automatically
 548  * group objects by the first byte of their object id. Use the IDX fanout
 549  * tables to group the data, copy to a local array, then sort.
 550  *
 551  * Copy only the de-duplicated entries (selected by most-recent modified time
 552  * of a packfile containing the object).
 553  */
 554 static struct pack_midx_entry *get_sorted_entries(struct multi_pack_index *m,
 555                                                   struct pack_info *info,
 556                                                   uint32_t nr_packs,
 557                                                   uint32_t *nr_objects)
 558 {
 559         uint32_t cur_fanout, cur_pack, cur_object;
 560         uint32_t alloc_fanout, alloc_objects, total_objects = 0;
 561         struct pack_midx_entry *entries_by_fanout = NULL;
 562         struct pack_midx_entry *deduplicated_entries = NULL;
 563         uint32_t start_pack = m ? m->num_packs : 0;
 564
 565         for (cur_pack = start_pack; cur_pack < nr_packs; cur_pack++)
 566                 total_objects += info[cur_pack].p->num_objects;
 567
 568         /*
 569          * As we de-duplicate by fanout value, we expect the fanout
 570          * slices to be evenly distributed, with some noise. Hence,
 571          * allocate slightly more than one 256th.
 572          */
 573         alloc_objects = alloc_fanout = total_objects > 3200 ? total_objects / 200 : 16;
 574
 575         ALLOC_ARRAY(entries_by_fanout, alloc_fanout);
 576         ALLOC_ARRAY(deduplicated_entries, alloc_objects);
 577         *nr_objects = 0;
 578
 579         for (cur_fanout = 0; cur_fanout < 256; cur_fanout++) {
 580                 uint32_t nr_fanout = 0;
 581
 582                 if (m) {
 583                         uint32_t start = 0, end;
 584
 585                         if (cur_fanout)
 586                                 start = ntohl(m->chunk_oid_fanout[cur_fanout - 1]);
 587                         end = ntohl(m->chunk_oid_fanout[cur_fanout]);
 588
 589                         for (cur_object = start; cur_object < end; cur_object++) {
 590                                 ALLOC_GROW(entries_by_fanout, nr_fanout + 1, alloc_fanout);
 591                                 nth_midxed_pack_midx_entry(m,
 592                                                            &entries_by_fanout[nr_fanout],
 593                                                            cur_object);
 594                                 nr_fanout++;
 595                         }
 596                 }
 597
 598                 for (cur_pack = start_pack; cur_pack < nr_packs; cur_pack++) {
 599                         uint32_t start = 0, end;
 600
 601                         if (cur_fanout)
 602                                 start = get_pack_fanout(info[cur_pack].p, cur_fanout - 1);
 603                         end = get_pack_fanout(info[cur_pack].p, cur_fanout);
 604
 605                         for (cur_object = start; cur_object < end; cur_object++) {
 606                                 ALLOC_GROW(entries_by_fanout, nr_fanout + 1, alloc_fanout);
 607                                 fill_pack_entry(cur_pack, info[cur_pack].p, cur_object, &entries_by_fanout[nr_fanout]);
 608                                 nr_fanout++;
 609                         }
 610                 }
 611
 612                 QSORT(entries_by_fanout, nr_fanout, midx_oid_compare);
 613
 614                 /*
 615                  * The batch is now sorted by OID and then mtime (descending).
 616                  * Take only the first duplicate.
 617                  */
 618                 for (cur_object = 0; cur_object < nr_fanout; cur_object++) {
 619                         if (cur_object && oideq(&entries_by_fanout[cur_object - 1].oid,
 620                                                 &entries_by_fanout[cur_object].oid))
 621                                 continue;
 622
 623                         ALLOC_GROW(deduplicated_entries, *nr_objects + 1, alloc_objects);
 624                         memcpy(&deduplicated_entries[*nr_objects],
 625                                &entries_by_fanout[cur_object],
 626                                sizeof(struct pack_midx_entry));
 627                         (*nr_objects)++;
 628                 }
 629         }
 630
 631         free(entries_by_fanout);
 632         return deduplicated_entries;
 633 }
 634
 635 static size_t write_midx_pack_names(struct hashfile *f,
 636                                     struct pack_info *info,
 637                                     uint32_t num_packs)
 638 {
 639         uint32_t i;
 640         unsigned char padding[MIDX_CHUNK_ALIGNMENT];
 641         size_t written = 0;
 642
 643         for (i = 0; i < num_packs; i++) {
 644                 size_t writelen;
 645
 646                 if (info[i].expired)
 647                         continue;
 648
 649                 if (i && strcmp(info[i].pack_name, info[i - 1].pack_name) <= 0)
 650                         BUG("incorrect pack-file order: %s before %s",
 651                             info[i - 1].pack_name,
 652                             info[i].pack_name);
 653
 654                 writelen = strlen(info[i].pack_name) + 1;
 655                 hashwrite(f, info[i].pack_name, writelen);
 656                 written += writelen;
 657         }
 658
 659         /* add padding to be aligned */
 660         i = MIDX_CHUNK_ALIGNMENT - (written % MIDX_CHUNK_ALIGNMENT);
 661         if (i < MIDX_CHUNK_ALIGNMENT) {
 662                 memset(padding, 0, sizeof(padding));
 663                 hashwrite(f, padding, i);
 664                 written += i;
 665         }
 666
 667         return written;
 668 }
 669
 670 static size_t write_midx_oid_fanout(struct hashfile *f,
 671                                     struct pack_midx_entry *objects,
 672                                     uint32_t nr_objects)
 673 {
 674         struct pack_midx_entry *list = objects;
 675         struct pack_midx_entry *last = objects + nr_objects;
 676         uint32_t count = 0;
 677         uint32_t i;
 678
 679         /*
 680         * Write the first-level table (the list is sorted,
 681         * but we use a 256-entry lookup to be able to avoid
 682         * having to do eight extra binary search iterations).
 683         */
 684         for (i = 0; i < 256; i++) {
 685                 struct pack_midx_entry *next = list;
 686
 687                 while (next < last && next->oid.hash[0] == i) {
 688                         count++;
 689                         next++;
 690                 }
 691
 692                 hashwrite_be32(f, count);
 693                 list = next;
 694         }
 695
 696         return MIDX_CHUNK_FANOUT_SIZE;
 697 }
 698
 699 static size_t write_midx_oid_lookup(struct hashfile *f, unsigned char hash_len,
 700                                     struct pack_midx_entry *objects,
 701                                     uint32_t nr_objects)
 702 {
 703         struct pack_midx_entry *list = objects;
 704         uint32_t i;
 705         size_t written = 0;
 706
 707         for (i = 0; i < nr_objects; i++) {
 708                 struct pack_midx_entry *obj = list++;
 709
 710                 if (i < nr_objects - 1) {
 711                         struct pack_midx_entry *next = list;
 712                         if (oidcmp(&obj->oid, &next->oid) >= 0)
 713                                 BUG("OIDs not in order: %s >= %s",
 714                                     oid_to_hex(&obj->oid),
 715                                     oid_to_hex(&next->oid));
 716                 }
 717
 718                 hashwrite(f, obj->oid.hash, (int)hash_len);
 719                 written += hash_len;
 720         }
 721
 722         return written;
 723 }
 724
 725 static size_t write_midx_object_offsets(struct hashfile *f, int large_offset_needed,
 726                                         uint32_t *perm,
 727                                         struct pack_midx_entry *objects, uint32_t nr_objects)
 728 {
 729         struct pack_midx_entry *list = objects;
 730         uint32_t i, nr_large_offset = 0;
 731         size_t written = 0;
 732
 733         for (i = 0; i < nr_objects; i++) {
 734                 struct pack_midx_entry *obj = list++;
 735
 736                 if (perm[obj->pack_int_id] == PACK_EXPIRED)
 737                         BUG("object %s is in an expired pack with int-id %d",
 738                             oid_to_hex(&obj->oid),
 739                             obj->pack_int_id);
 740
 741                 hashwrite_be32(f, perm[obj->pack_int_id]);
 742
 743                 if (large_offset_needed && obj->offset >> 31)
 744                         hashwrite_be32(f, MIDX_LARGE_OFFSET_NEEDED | nr_large_offset++);
 745                 else if (!large_offset_needed && obj->offset >> 32)
 746                         BUG("object %s requires a large offset (%"PRIx64") but the MIDX is not writing large offsets!",
 747                             oid_to_hex(&obj->oid),
 748                             obj->offset);
 749                 else
 750                         hashwrite_be32(f, (uint32_t)obj->offset);
 751
 752                 written += MIDX_CHUNK_OFFSET_WIDTH;
 753         }
 754
 755         return written;
 756 }
 757
 758 static size_t write_midx_large_offsets(struct hashfile *f, uint32_t nr_large_offset,
 759                                        struct pack_midx_entry *objects, uint32_t nr_objects)
 760 {
 761         struct pack_midx_entry *list = objects, *end = objects + nr_objects;
 762         size_t written = 0;
 763
 764         while (nr_large_offset) {
 765                 struct pack_midx_entry *obj;
 766                 uint64_t offset;
 767
 768                 if (list >= end)
 769                         BUG("too many large-offset objects");
 770
 771                 obj = list++;
 772                 offset = obj->offset;
 773
 774                 if (!(offset >> 31))
 775                         continue;
 776
 777                 hashwrite_be32(f, offset >> 32);
 778                 hashwrite_be32(f, offset & 0xffffffffUL);
 779                 written += 2 * sizeof(uint32_t);
 780
 781                 nr_large_offset--;
 782         }
 783
 784         return written;
 785 }
 786
 787 static int write_midx_internal(const char *object_dir, struct multi_pack_index *m,
 788                                struct string_list *packs_to_drop)
 789 {
 790         unsigned char cur_chunk, num_chunks = 0;
 791         char *midx_name;
 792         uint32_t i;
 793         struct hashfile *f = NULL;
 794         struct lock_file lk;
 795         struct pack_list packs;
 796         uint32_t *pack_perm = NULL;
 797         uint64_t written = 0;
 798         uint32_t chunk_ids[MIDX_MAX_CHUNKS + 1];
 799         uint64_t chunk_offsets[MIDX_MAX_CHUNKS + 1];
 800         uint32_t nr_entries, num_large_offsets = 0;
 801         struct pack_midx_entry *entries = NULL;
 802         int large_offsets_needed = 0;
 803         int pack_name_concat_len = 0;
 804         int dropped_packs = 0;
 805         int result = 0;
 806
 807         midx_name = get_midx_filename(object_dir);
 808         if (safe_create_leading_directories(midx_name)) {
 809                 UNLEAK(midx_name);
 810                 die_errno(_("unable to create leading directories of %s"),
 811                           midx_name);
 812         }
 813
 814         if (m)
 815                 packs.m = m;
 816         else
 817                 packs.m = load_multi_pack_index(object_dir, 1);
 818
 819         packs.nr = 0;
 820         packs.alloc = packs.m ? packs.m->num_packs : 16;
 821         packs.info = NULL;
 822         ALLOC_ARRAY(packs.info, packs.alloc);
 823
 824         if (packs.m) {
 825                 for (i = 0; i < packs.m->num_packs; i++) {
 826                         ALLOC_GROW(packs.info, packs.nr + 1, packs.alloc);
 827
 828                         packs.info[packs.nr].orig_pack_int_id = i;
 829                         packs.info[packs.nr].pack_name = xstrdup(packs.m->pack_names[i]);
 830                         packs.info[packs.nr].p = NULL;
 831                         packs.info[packs.nr].expired = 0;
 832                         packs.nr++;
 833                 }
 834         }
 835
 836         for_each_file_in_pack_dir(object_dir, add_pack_to_midx, &packs);
 837
 838         if (packs.m && packs.nr == packs.m->num_packs && !packs_to_drop)
 839                 goto cleanup;
 840
 841         entries = get_sorted_entries(packs.m, packs.info, packs.nr, &nr_entries);
 842
 843         for (i = 0; i < nr_entries; i++) {
 844                 if (entries[i].offset > 0x7fffffff)
 845                         num_large_offsets++;
 846                 if (entries[i].offset > 0xffffffff)
 847                         large_offsets_needed = 1;
 848         }
 849
 850         QSORT(packs.info, packs.nr, pack_info_compare);
 851
 852         if (packs_to_drop && packs_to_drop->nr) {
 853                 int drop_index = 0;
 854                 int missing_drops = 0;
 855
 856                 for (i = 0; i < packs.nr && drop_index < packs_to_drop->nr; i++) {
 857                         int cmp = strcmp(packs.info[i].pack_name,
 858                                          packs_to_drop->items[drop_index].string);
 859
 860                         if (!cmp) {
 861                                 drop_index++;
 862                                 packs.info[i].expired = 1;
 863                         } else if (cmp > 0) {
 864                                 error(_("did not see pack-file %s to drop"),
 865                                       packs_to_drop->items[drop_index].string);
 866                                 drop_index++;
 867                                 missing_drops++;
 868                                 i--;
 869                         } else {
 870                                 packs.info[i].expired = 0;
 871                         }
 872                 }
 873
 874                 if (missing_drops) {
 875                         result = 1;
 876                         goto cleanup;
 877                 }
 878         }
 879
 880         /*
 881          * pack_perm stores a permutation between pack-int-ids from the
 882          * previous multi-pack-index to the new one we are writing:
 883          *
 884          * pack_perm[old_id] = new_id
 885          */
 886         ALLOC_ARRAY(pack_perm, packs.nr);
 887         for (i = 0; i < packs.nr; i++) {
 888                 if (packs.info[i].expired) {
 889                         dropped_packs++;
 890                         pack_perm[packs.info[i].orig_pack_int_id] = PACK_EXPIRED;
 891                 } else {
 892                         pack_perm[packs.info[i].orig_pack_int_id] = i - dropped_packs;
 893                 }
 894         }
 895
 896         for (i = 0; i < packs.nr; i++) {
 897                 if (!packs.info[i].expired)
 898                         pack_name_concat_len += strlen(packs.info[i].pack_name) + 1;
 899         }
 900
 901         if (pack_name_concat_len % MIDX_CHUNK_ALIGNMENT)
 902                 pack_name_concat_len += MIDX_CHUNK_ALIGNMENT -
 903                                         (pack_name_concat_len % MIDX_CHUNK_ALIGNMENT);
 904
 905         hold_lock_file_for_update(&lk, midx_name, LOCK_DIE_ON_ERROR);
 906         f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
 907         FREE_AND_NULL(midx_name);
 908
 909         if (packs.m)
 910                 close_midx(packs.m);
 911
 912         cur_chunk = 0;
 913         num_chunks = large_offsets_needed ? 5 : 4;
 914
 915         written = write_midx_header(f, num_chunks, packs.nr - dropped_packs);
 916
 917         chunk_ids[cur_chunk] = MIDX_CHUNKID_PACKNAMES;
 918         chunk_offsets[cur_chunk] = written + (num_chunks + 1) * MIDX_CHUNKLOOKUP_WIDTH;
 919
 920         cur_chunk++;
 921         chunk_ids[cur_chunk] = MIDX_CHUNKID_OIDFANOUT;
 922         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + pack_name_concat_len;
 923
 924         cur_chunk++;
 925         chunk_ids[cur_chunk] = MIDX_CHUNKID_OIDLOOKUP;
 926         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + MIDX_CHUNK_FANOUT_SIZE;
 927
 928         cur_chunk++;
 929         chunk_ids[cur_chunk] = MIDX_CHUNKID_OBJECTOFFSETS;
 930         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + nr_entries * the_hash_algo->rawsz;
 931
 932         cur_chunk++;
 933         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + nr_entries * MIDX_CHUNK_OFFSET_WIDTH;
 934         if (large_offsets_needed) {
 935                 chunk_ids[cur_chunk] = MIDX_CHUNKID_LARGEOFFSETS;
 936
 937                 cur_chunk++;
 938                 chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] +
 939                                            num_large_offsets * MIDX_CHUNK_LARGE_OFFSET_WIDTH;
 940         }
 941
 942         chunk_ids[cur_chunk] = 0;
 943
 944         for (i = 0; i <= num_chunks; i++) {
 945                 if (i && chunk_offsets[i] < chunk_offsets[i - 1])
 946                         BUG("incorrect chunk offsets: %"PRIu64" before %"PRIu64,
 947                             chunk_offsets[i - 1],
 948                             chunk_offsets[i]);
 949
 950                 if (chunk_offsets[i] % MIDX_CHUNK_ALIGNMENT)
 951                         BUG("chunk offset %"PRIu64" is not properly aligned",
 952                             chunk_offsets[i]);
 953
 954                 hashwrite_be32(f, chunk_ids[i]);
 955                 hashwrite_be32(f, chunk_offsets[i] >> 32);
 956                 hashwrite_be32(f, chunk_offsets[i]);
 957
 958                 written += MIDX_CHUNKLOOKUP_WIDTH;
 959         }
 960
 961         for (i = 0; i < num_chunks; i++) {
 962                 if (written != chunk_offsets[i])
 963                         BUG("incorrect chunk offset (%"PRIu64" != %"PRIu64") for chunk id %"PRIx32,
 964                             chunk_offsets[i],
 965                             written,
 966                             chunk_ids[i]);
 967
 968                 switch (chunk_ids[i]) {
 969                         case MIDX_CHUNKID_PACKNAMES:
 970                                 written += write_midx_pack_names(f, packs.info, packs.nr);
 971                                 break;
 972
 973                         case MIDX_CHUNKID_OIDFANOUT:
 974                                 written += write_midx_oid_fanout(f, entries, nr_entries);
 975                                 break;
 976
 977                         case MIDX_CHUNKID_OIDLOOKUP:
 978                                 written += write_midx_oid_lookup(f, the_hash_algo->rawsz, entries, nr_entries);
 979                                 break;
 980
 981                         case MIDX_CHUNKID_OBJECTOFFSETS:
 982                                 written += write_midx_object_offsets(f, large_offsets_needed, pack_perm, entries, nr_entries);
 983                                 break;
 984
 985                         case MIDX_CHUNKID_LARGEOFFSETS:
 986                                 written += write_midx_large_offsets(f, num_large_offsets, entries, nr_entries);
 987                                 break;
 988
 989                         default:
 990                                 BUG("trying to write unknown chunk id %"PRIx32,
 991                                     chunk_ids[i]);
 992                 }
 993         }
 994
 995         if (written != chunk_offsets[num_chunks])
 996                 BUG("incorrect final offset %"PRIu64" != %"PRIu64,
 997                     written,
 998                     chunk_offsets[num_chunks]);
 999
1000         finalize_hashfile(f, NULL, CSUM_FSYNC | CSUM_HASH_IN_STREAM);
1001         commit_lock_file(&lk);
1002
1003 cleanup:
1004         for (i = 0; i < packs.nr; i++) {
1005                 if (packs.info[i].p) {
1006                         close_pack(packs.info[i].p);
1007                         free(packs.info[i].p);
1008                 }
1009                 free(packs.info[i].pack_name);
1010         }
1011
1012         free(packs.info);
1013         free(entries);
1014         free(pack_perm);
1015         free(midx_name);
1016         return result;
1017 }
1018
1019 int write_midx_file(const char *object_dir)
1020 {
1021         return write_midx_internal(object_dir, NULL, NULL);
1022 }
1023
1024 void clear_midx_file(struct repository *r)
1025 {
1026         char *midx = get_midx_filename(r->objects->odb->path);
1027
1028         if (r->objects && r->objects->multi_pack_index) {
1029                 close_midx(r->objects->multi_pack_index);
1030                 r->objects->multi_pack_index = NULL;
1031         }
1032
1033         if (remove_path(midx)) {
1034                 UNLEAK(midx);
1035                 die(_("failed to clear multi-pack-index at %s"), midx);
1036         }
1037
1038         free(midx);
1039 }
1040
1041 static int verify_midx_error;
1042
1043 static void midx_report(const char *fmt, ...)
1044 {
1045         va_list ap;
1046         verify_midx_error = 1;
1047         va_start(ap, fmt);
1048         vfprintf(stderr, fmt, ap);
1049         fprintf(stderr, "\n");
1050         va_end(ap);
1051 }
1052
1053 struct pair_pos_vs_id
1054 {
1055         uint32_t pos;
1056         uint32_t pack_int_id;
1057 };
1058
1059 static int compare_pair_pos_vs_id(const void *_a, const void *_b)
1060 {
1061         struct pair_pos_vs_id *a = (struct pair_pos_vs_id *)_a;
1062         struct pair_pos_vs_id *b = (struct pair_pos_vs_id *)_b;
1063
1064         return b->pack_int_id - a->pack_int_id;
1065 }
1066
1067 /*
1068  * Limit calls to display_progress() for performance reasons.
1069  * The interval here was arbitrarily chosen.
1070  */
1071 #define SPARSE_PROGRESS_INTERVAL (1 << 12)
1072 #define midx_display_sparse_progress(progress, n) \
1073         do { \
1074                 uint64_t _n = (n); \
1075                 if ((_n & (SPARSE_PROGRESS_INTERVAL - 1)) == 0) \
1076                         display_progress(progress, _n); \
1077         } while (0)
1078
1079 int verify_midx_file(struct repository *r, const char *object_dir)
1080 {
1081         struct pair_pos_vs_id *pairs = NULL;
1082         uint32_t i;
1083         struct progress *progress;
1084         struct multi_pack_index *m = load_multi_pack_index(object_dir, 1);
1085         verify_midx_error = 0;
1086
1087         if (!m)
1088                 return 0;
1089
1090         progress = start_progress(_("Looking for referenced packfiles"),
1091                                   m->num_packs);
1092         for (i = 0; i < m->num_packs; i++) {
1093                 if (prepare_midx_pack(r, m, i))
1094                         midx_report("failed to load pack in position %d", i);
1095
1096                 display_progress(progress, i + 1);
1097         }
1098         stop_progress(&progress);
1099
1100         for (i = 0; i < 255; i++) {
1101                 uint32_t oid_fanout1 = ntohl(m->chunk_oid_fanout[i]);
1102                 uint32_t oid_fanout2 = ntohl(m->chunk_oid_fanout[i + 1]);
1103
1104                 if (oid_fanout1 > oid_fanout2)
1105                         midx_report(_("oid fanout out of order: fanout[%d] = %"PRIx32" > %"PRIx32" = fanout[%d]"),
1106                                     i, oid_fanout1, oid_fanout2, i + 1);
1107         }
1108
1109         progress = start_sparse_progress(_("Verifying OID order in MIDX"),
1110                                          m->num_objects - 1);
1111         for (i = 0; i < m->num_objects - 1; i++) {
1112                 struct object_id oid1, oid2;
1113
1114                 nth_midxed_object_oid(&oid1, m, i);
1115                 nth_midxed_object_oid(&oid2, m, i + 1);
1116
1117                 if (oidcmp(&oid1, &oid2) >= 0)
1118                         midx_report(_("oid lookup out of order: oid[%d] = %s >= %s = oid[%d]"),
1119                                     i, oid_to_hex(&oid1), oid_to_hex(&oid2), i + 1);
1120
1121                 midx_display_sparse_progress(progress, i + 1);
1122         }
1123         stop_progress(&progress);
1124
1125         /*
1126          * Create an array mapping each object to its packfile id.  Sort it
1127          * to group the objects by packfile.  Use this permutation to visit
1128          * each of the objects and only require 1 packfile to be open at a
1129          * time.
1130          */
1131         ALLOC_ARRAY(pairs, m->num_objects);
1132         for (i = 0; i < m->num_objects; i++) {
1133                 pairs[i].pos = i;
1134                 pairs[i].pack_int_id = nth_midxed_pack_int_id(m, i);
1135         }
1136
1137         progress = start_sparse_progress(_("Sorting objects by packfile"),
1138                                          m->num_objects);
1139         display_progress(progress, 0); /* TODO: Measure QSORT() progress */
1140         QSORT(pairs, m->num_objects, compare_pair_pos_vs_id);
1141         stop_progress(&progress);
1142
1143         progress = start_sparse_progress(_("Verifying object offsets"), m->num_objects);
1144         for (i = 0; i < m->num_objects; i++) {
1145                 struct object_id oid;
1146                 struct pack_entry e;
1147                 off_t m_offset, p_offset;
1148
1149                 if (i > 0 && pairs[i-1].pack_int_id != pairs[i].pack_int_id &&
1150                     m->packs[pairs[i-1].pack_int_id])
1151                 {
1152                         close_pack_fd(m->packs[pairs[i-1].pack_int_id]);
1153                         close_pack_index(m->packs[pairs[i-1].pack_int_id]);
1154                 }
1155
1156                 nth_midxed_object_oid(&oid, m, pairs[i].pos);
1157
1158                 if (!fill_midx_entry(r, &oid, &e, m)) {
1159                         midx_report(_("failed to load pack entry for oid[%d] = %s"),
1160                                     pairs[i].pos, oid_to_hex(&oid));
1161                         continue;
1162                 }
1163
1164                 if (open_pack_index(e.p)) {
1165                         midx_report(_("failed to load pack-index for packfile %s"),
1166                                     e.p->pack_name);
1167                         break;
1168                 }
1169
1170                 m_offset = e.offset;
1171                 p_offset = find_pack_entry_one(oid.hash, e.p);
1172
1173                 if (m_offset != p_offset)
1174                         midx_report(_("incorrect object offset for oid[%d] = %s: %"PRIx64" != %"PRIx64),
1175                                     pairs[i].pos, oid_to_hex(&oid), m_offset, p_offset);
1176
1177                 midx_display_sparse_progress(progress, i + 1);
1178         }
1179         stop_progress(&progress);
1180
1181         free(pairs);
1182
1183         return verify_midx_error;
1184 }
1185
1186 int expire_midx_packs(struct repository *r, const char *object_dir)
1187 {
1188         uint32_t i, *count, result = 0;
1189         struct string_list packs_to_drop = STRING_LIST_INIT_DUP;
1190         struct multi_pack_index *m = load_multi_pack_index(object_dir, 1);
1191
1192         if (!m)
1193                 return 0;
1194
1195         count = xcalloc(m->num_packs, sizeof(uint32_t));
1196         for (i = 0; i < m->num_objects; i++) {
1197                 int pack_int_id = nth_midxed_pack_int_id(m, i);
1198                 count[pack_int_id]++;
1199         }
1200
1201         for (i = 0; i < m->num_packs; i++) {
1202                 char *pack_name;
1203
1204                 if (count[i])
1205                         continue;
1206
1207                 if (prepare_midx_pack(r, m, i))
1208                         continue;
1209
1210                 if (m->packs[i]->pack_keep)
1211                         continue;
1212
1213                 pack_name = xstrdup(m->packs[i]->pack_name);
1214                 close_pack(m->packs[i]);
1215
1216                 string_list_insert(&packs_to_drop, m->pack_names[i]);
1217                 unlink_pack_path(pack_name, 0);
1218                 free(pack_name);
1219         }
1220
1221         free(count);
1222
1223         if (packs_to_drop.nr)
1224                 result = write_midx_internal(object_dir, m, &packs_to_drop);
1225
1226         string_list_clear(&packs_to_drop, 0);
1227         return result;
1228 }
1229
1230 struct repack_info {
1231         timestamp_t mtime;
1232         uint32_t referenced_objects;
1233         uint32_t pack_int_id;
1234 };
1235
1236 static int compare_by_mtime(const void *a_, const void *b_)
1237 {
1238         const struct repack_info *a, *b;
1239
1240         a = (const struct repack_info *)a_;
1241         b = (const struct repack_info *)b_;
1242
1243         if (a->mtime < b->mtime)
1244                 return -1;
1245         if (a->mtime > b->mtime)
1246                 return 1;
1247         return 0;
1248 }
1249
1250 static int fill_included_packs_all(struct multi_pack_index *m,
1251                                    unsigned char *include_pack)
1252 {
1253         uint32_t i;
1254
1255         for (i = 0; i < m->num_packs; i++)
1256                 include_pack[i] = 1;
1257
1258         return m->num_packs < 2;
1259 }
1260
1261 static int fill_included_packs_batch(struct repository *r,
1262                                      struct multi_pack_index *m,
1263                                      unsigned char *include_pack,
1264                                      size_t batch_size)
1265 {
1266         uint32_t i, packs_to_repack;
1267         size_t total_size;
1268         struct repack_info *pack_info = xcalloc(m->num_packs, sizeof(struct repack_info));
1269
1270         for (i = 0; i < m->num_packs; i++) {
1271                 pack_info[i].pack_int_id = i;
1272
1273                 if (prepare_midx_pack(r, m, i))
1274                         continue;
1275
1276                 pack_info[i].mtime = m->packs[i]->mtime;
1277         }
1278
1279         for (i = 0; batch_size && i < m->num_objects; i++) {
1280                 uint32_t pack_int_id = nth_midxed_pack_int_id(m, i);
1281                 pack_info[pack_int_id].referenced_objects++;
1282         }
1283
1284         QSORT(pack_info, m->num_packs, compare_by_mtime);
1285
1286         total_size = 0;
1287         packs_to_repack = 0;
1288         for (i = 0; total_size < batch_size && i < m->num_packs; i++) {
1289                 int pack_int_id = pack_info[i].pack_int_id;
1290                 struct packed_git *p = m->packs[pack_int_id];
1291                 size_t expected_size;
1292
1293                 if (!p)
1294                         continue;
1295                 if (open_pack_index(p) || !p->num_objects)
1296                         continue;
1297
1298                 expected_size = (size_t)(p->pack_size
1299                                          * pack_info[i].referenced_objects);
1300                 expected_size /= p->num_objects;
1301
1302                 if (expected_size >= batch_size)
1303                         continue;
1304
1305                 packs_to_repack++;
1306                 total_size += expected_size;
1307                 include_pack[pack_int_id] = 1;
1308         }
1309
1310         free(pack_info);
1311
1312         if (total_size < batch_size || packs_to_repack < 2)
1313                 return 1;
1314
1315         return 0;
1316 }
1317
1318 int midx_repack(struct repository *r, const char *object_dir, size_t batch_size)
1319 {
1320         int result = 0;
1321         uint32_t i;
1322         unsigned char *include_pack;
1323         struct child_process cmd = CHILD_PROCESS_INIT;
1324         struct strbuf base_name = STRBUF_INIT;
1325         struct multi_pack_index *m = load_multi_pack_index(object_dir, 1);
1326
1327         if (!m)
1328                 return 0;
1329
1330         include_pack = xcalloc(m->num_packs, sizeof(unsigned char));
1331
1332         if (batch_size) {
1333                 if (fill_included_packs_batch(r, m, include_pack, batch_size))
1334                         goto cleanup;
1335         } else if (fill_included_packs_all(m, include_pack))
1336                 goto cleanup;
1337
1338         argv_array_push(&cmd.args, "pack-objects");
1339
1340         strbuf_addstr(&base_name, object_dir);
1341         strbuf_addstr(&base_name, "/pack/pack");
1342         argv_array_push(&cmd.args, base_name.buf);
1343         strbuf_release(&base_name);
1344
1345         cmd.git_cmd = 1;
1346         cmd.in = cmd.out = -1;
1347
1348         if (start_command(&cmd)) {
1349                 error(_("could not start pack-objects"));
1350                 result = 1;
1351                 goto cleanup;
1352         }
1353
1354         for (i = 0; i < m->num_objects; i++) {
1355                 struct object_id oid;
1356                 uint32_t pack_int_id = nth_midxed_pack_int_id(m, i);
1357
1358                 if (!include_pack[pack_int_id])
1359                         continue;
1360
1361                 nth_midxed_object_oid(&oid, m, i);
1362                 xwrite(cmd.in, oid_to_hex(&oid), the_hash_algo->hexsz);
1363                 xwrite(cmd.in, "\n", 1);
1364         }
1365         close(cmd.in);
1366
1367         if (finish_command(&cmd)) {
1368                 error(_("could not finish pack-objects"));
1369                 result = 1;
1370                 goto cleanup;
1371         }
1372
1373         result = write_midx_internal(object_dir, m, NULL);
1374         m = NULL;
1375
1376 cleanup:
1377         if (m)
1378                 close_midx(m);
1379         free(include_pack);
1380         return result;
1381 }