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_HEADER_SIZE 12
  21 #define MIDX_MIN_SIZE (MIDX_HEADER_SIZE + the_hash_algo->rawsz)
  22
  23 #define MIDX_MAX_CHUNKS 5
  24 #define MIDX_CHUNK_ALIGNMENT 4
  25 #define MIDX_CHUNKID_PACKNAMES 0x504e414d /* "PNAM" */
  26 #define MIDX_CHUNKID_OIDFANOUT 0x4f494446 /* "OIDF" */
  27 #define MIDX_CHUNKID_OIDLOOKUP 0x4f49444c /* "OIDL" */
  28 #define MIDX_CHUNKID_OBJECTOFFSETS 0x4f4f4646 /* "OOFF" */
  29 #define MIDX_CHUNKID_LARGEOFFSETS 0x4c4f4646 /* "LOFF" */
  30 #define MIDX_CHUNKLOOKUP_WIDTH (sizeof(uint32_t) + sizeof(uint64_t))
  31 #define MIDX_CHUNK_FANOUT_SIZE (sizeof(uint32_t) * 256)
  32 #define MIDX_CHUNK_OFFSET_WIDTH (2 * sizeof(uint32_t))
  33 #define MIDX_CHUNK_LARGE_OFFSET_WIDTH (sizeof(uint64_t))
  34 #define MIDX_LARGE_OFFSET_NEEDED 0x80000000
  35
  36 #define PACK_EXPIRED UINT_MAX
  37
  38 static uint8_t oid_version(void)
  39 {
  40         switch (hash_algo_by_ptr(the_hash_algo)) {
  41         case GIT_HASH_SHA1:
  42                 return 1;
  43         case GIT_HASH_SHA256:
  44                 return 2;
  45         default:
  46                 die(_("invalid hash version"));
  47         }
  48 }
  49
  50 static char *get_midx_filename(const char *object_dir)
  51 {
  52         return xstrfmt("%s/pack/multi-pack-index", object_dir);
  53 }
  54
  55 struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local)
  56 {
  57         struct multi_pack_index *m = NULL;
  58         int fd;
  59         struct stat st;
  60         size_t midx_size;
  61         void *midx_map = NULL;
  62         uint32_t hash_version;
  63         char *midx_name = get_midx_filename(object_dir);
  64         uint32_t i;
  65         const char *cur_pack_name;
  66
  67         fd = git_open(midx_name);
  68
  69         if (fd < 0)
  70                 goto cleanup_fail;
  71         if (fstat(fd, &st)) {
  72                 error_errno(_("failed to read %s"), midx_name);
  73                 goto cleanup_fail;
  74         }
  75
  76         midx_size = xsize_t(st.st_size);
  77
  78         if (midx_size < MIDX_MIN_SIZE) {
  79                 error(_("multi-pack-index file %s is too small"), midx_name);
  80                 goto cleanup_fail;
  81         }
  82
  83         FREE_AND_NULL(midx_name);
  84
  85         midx_map = xmmap(NULL, midx_size, PROT_READ, MAP_PRIVATE, fd, 0);
  86         close(fd);
  87
  88         FLEX_ALLOC_STR(m, object_dir, object_dir);
  89         m->data = midx_map;
  90         m->data_len = midx_size;
  91         m->local = local;
  92
  93         m->signature = get_be32(m->data);
  94         if (m->signature != MIDX_SIGNATURE)
  95                 die(_("multi-pack-index signature 0x%08x does not match signature 0x%08x"),
  96                       m->signature, MIDX_SIGNATURE);
  97
  98         m->version = m->data[MIDX_BYTE_FILE_VERSION];
  99         if (m->version != MIDX_VERSION)
 100                 die(_("multi-pack-index version %d not recognized"),
 101                       m->version);
 102
 103         hash_version = m->data[MIDX_BYTE_HASH_VERSION];
 104         if (hash_version != oid_version()) {
 105                 error(_("multi-pack-index hash version %u does not match version %u"),
 106                       hash_version, oid_version());
 107                 goto cleanup_fail;
 108         }
 109         m->hash_len = the_hash_algo->rawsz;
 110
 111         m->num_chunks = m->data[MIDX_BYTE_NUM_CHUNKS];
 112
 113         m->num_packs = get_be32(m->data + MIDX_BYTE_NUM_PACKS);
 114
 115         for (i = 0; i < m->num_chunks; i++) {
 116                 uint32_t chunk_id = get_be32(m->data + MIDX_HEADER_SIZE +
 117                                              MIDX_CHUNKLOOKUP_WIDTH * i);
 118                 uint64_t chunk_offset = get_be64(m->data + MIDX_HEADER_SIZE + 4 +
 119                                                  MIDX_CHUNKLOOKUP_WIDTH * i);
 120
 121                 if (chunk_offset >= m->data_len)
 122                         die(_("invalid chunk offset (too large)"));
 123
 124                 switch (chunk_id) {
 125                         case MIDX_CHUNKID_PACKNAMES:
 126                                 m->chunk_pack_names = m->data + chunk_offset;
 127                                 break;
 128
 129                         case MIDX_CHUNKID_OIDFANOUT:
 130                                 m->chunk_oid_fanout = (uint32_t *)(m->data + chunk_offset);
 131                                 break;
 132
 133                         case MIDX_CHUNKID_OIDLOOKUP:
 134                                 m->chunk_oid_lookup = m->data + chunk_offset;
 135                                 break;
 136
 137                         case MIDX_CHUNKID_OBJECTOFFSETS:
 138                                 m->chunk_object_offsets = m->data + chunk_offset;
 139                                 break;
 140
 141                         case MIDX_CHUNKID_LARGEOFFSETS:
 142                                 m->chunk_large_offsets = m->data + chunk_offset;
 143                                 break;
 144
 145                         case 0:
 146                                 die(_("terminating multi-pack-index chunk id appears earlier than expected"));
 147                                 break;
 148
 149                         default:
 150                                 /*
 151                                  * Do nothing on unrecognized chunks, allowing future
 152                                  * extensions to add optional chunks.
 153                                  */
 154                                 break;
 155                 }
 156         }
 157
 158         if (!m->chunk_pack_names)
 159                 die(_("multi-pack-index missing required pack-name chunk"));
 160         if (!m->chunk_oid_fanout)
 161                 die(_("multi-pack-index missing required OID fanout chunk"));
 162         if (!m->chunk_oid_lookup)
 163                 die(_("multi-pack-index missing required OID lookup chunk"));
 164         if (!m->chunk_object_offsets)
 165                 die(_("multi-pack-index missing required object offsets chunk"));
 166
 167         m->num_objects = ntohl(m->chunk_oid_fanout[255]);
 168
 169         m->pack_names = xcalloc(m->num_packs, sizeof(*m->pack_names));
 170         m->packs = xcalloc(m->num_packs, sizeof(*m->packs));
 171
 172         cur_pack_name = (const char *)m->chunk_pack_names;
 173         for (i = 0; i < m->num_packs; i++) {
 174                 m->pack_names[i] = cur_pack_name;
 175
 176                 cur_pack_name += strlen(cur_pack_name) + 1;
 177
 178                 if (i && strcmp(m->pack_names[i], m->pack_names[i - 1]) <= 0)
 179                         die(_("multi-pack-index pack names out of order: '%s' before '%s'"),
 180                               m->pack_names[i - 1],
 181                               m->pack_names[i]);
 182         }
 183
 184         trace2_data_intmax("midx", the_repository, "load/num_packs", m->num_packs);
 185         trace2_data_intmax("midx", the_repository, "load/num_objects", m->num_objects);
 186
 187         return m;
 188
 189 cleanup_fail:
 190         free(m);
 191         free(midx_name);
 192         if (midx_map)
 193                 munmap(midx_map, midx_size);
 194         if (0 <= fd)
 195                 close(fd);
 196         return NULL;
 197 }
 198
 199 void close_midx(struct multi_pack_index *m)
 200 {
 201         uint32_t i;
 202
 203         if (!m)
 204                 return;
 205
 206         munmap((unsigned char *)m->data, m->data_len);
 207
 208         for (i = 0; i < m->num_packs; i++) {
 209                 if (m->packs[i])
 210                         m->packs[i]->multi_pack_index = 0;
 211         }
 212         FREE_AND_NULL(m->packs);
 213         FREE_AND_NULL(m->pack_names);
 214 }
 215
 216 int prepare_midx_pack(struct repository *r, struct multi_pack_index *m, uint32_t pack_int_id)
 217 {
 218         struct strbuf pack_name = STRBUF_INIT;
 219         struct packed_git *p;
 220
 221         if (pack_int_id >= m->num_packs)
 222                 die(_("bad pack-int-id: %u (%u total packs)"),
 223                     pack_int_id, m->num_packs);
 224
 225         if (m->packs[pack_int_id])
 226                 return 0;
 227
 228         strbuf_addf(&pack_name, "%s/pack/%s", m->object_dir,
 229                     m->pack_names[pack_int_id]);
 230
 231         p = add_packed_git(pack_name.buf, pack_name.len, m->local);
 232         strbuf_release(&pack_name);
 233
 234         if (!p)
 235                 return 1;
 236
 237         p->multi_pack_index = 1;
 238         m->packs[pack_int_id] = p;
 239         install_packed_git(r, p);
 240         list_add_tail(&p->mru, &r->objects->packed_git_mru);
 241
 242         return 0;
 243 }
 244
 245 int bsearch_midx(const struct object_id *oid, struct multi_pack_index *m, uint32_t *result)
 246 {
 247         return bsearch_hash(oid->hash, m->chunk_oid_fanout, m->chunk_oid_lookup,
 248                             the_hash_algo->rawsz, result);
 249 }
 250
 251 struct object_id *nth_midxed_object_oid(struct object_id *oid,
 252                                         struct multi_pack_index *m,
 253                                         uint32_t n)
 254 {
 255         if (n >= m->num_objects)
 256                 return NULL;
 257
 258         hashcpy(oid->hash, m->chunk_oid_lookup + m->hash_len * n);
 259         return oid;
 260 }
 261
 262 static off_t nth_midxed_offset(struct multi_pack_index *m, uint32_t pos)
 263 {
 264         const unsigned char *offset_data;
 265         uint32_t offset32;
 266
 267         offset_data = m->chunk_object_offsets + pos * MIDX_CHUNK_OFFSET_WIDTH;
 268         offset32 = get_be32(offset_data + sizeof(uint32_t));
 269
 270         if (m->chunk_large_offsets && offset32 & MIDX_LARGE_OFFSET_NEEDED) {
 271                 if (sizeof(off_t) < sizeof(uint64_t))
 272                         die(_("multi-pack-index stores a 64-bit offset, but off_t is too small"));
 273
 274                 offset32 ^= MIDX_LARGE_OFFSET_NEEDED;
 275                 return get_be64(m->chunk_large_offsets + sizeof(uint64_t) * offset32);
 276         }
 277
 278         return offset32;
 279 }
 280
 281 static uint32_t nth_midxed_pack_int_id(struct multi_pack_index *m, uint32_t pos)
 282 {
 283         return get_be32(m->chunk_object_offsets + pos * MIDX_CHUNK_OFFSET_WIDTH);
 284 }
 285
 286 static int nth_midxed_pack_entry(struct repository *r,
 287                                  struct multi_pack_index *m,
 288                                  struct pack_entry *e,
 289                                  uint32_t pos)
 290 {
 291         uint32_t pack_int_id;
 292         struct packed_git *p;
 293
 294         if (pos >= m->num_objects)
 295                 return 0;
 296
 297         pack_int_id = nth_midxed_pack_int_id(m, pos);
 298
 299         if (prepare_midx_pack(r, m, pack_int_id))
 300                 die(_("error preparing packfile from multi-pack-index"));
 301         p = m->packs[pack_int_id];
 302
 303         /*
 304         * We are about to tell the caller where they can locate the
 305         * requested object.  We better make sure the packfile is
 306         * still here and can be accessed before supplying that
 307         * answer, as it may have been deleted since the MIDX was
 308         * loaded!
 309         */
 310         if (!is_pack_valid(p))
 311                 return 0;
 312
 313         if (p->num_bad_objects) {
 314                 uint32_t i;
 315                 struct object_id oid;
 316                 nth_midxed_object_oid(&oid, m, pos);
 317                 for (i = 0; i < p->num_bad_objects; i++)
 318                         if (hasheq(oid.hash,
 319                                    p->bad_object_sha1 + the_hash_algo->rawsz * i))
 320                                 return 0;
 321         }
 322
 323         e->offset = nth_midxed_offset(m, pos);
 324         e->p = p;
 325
 326         return 1;
 327 }
 328
 329 int fill_midx_entry(struct repository * r,
 330                     const struct object_id *oid,
 331                     struct pack_entry *e,
 332                     struct multi_pack_index *m)
 333 {
 334         uint32_t pos;
 335
 336         if (!bsearch_midx(oid, m, &pos))
 337                 return 0;
 338
 339         return nth_midxed_pack_entry(r, m, e, pos);
 340 }
 341
 342 /* Match "foo.idx" against either "foo.pack" _or_ "foo.idx". */
 343 static int cmp_idx_or_pack_name(const char *idx_or_pack_name,
 344                                 const char *idx_name)
 345 {
 346         /* Skip past any initial matching prefix. */
 347         while (*idx_name && *idx_name == *idx_or_pack_name) {
 348                 idx_name++;
 349                 idx_or_pack_name++;
 350         }
 351
 352         /*
 353          * If we didn't match completely, we may have matched "pack-1234." and
 354          * be left with "idx" and "pack" respectively, which is also OK. We do
 355          * not have to check for "idx" and "idx", because that would have been
 356          * a complete match (and in that case these strcmps will be false, but
 357          * we'll correctly return 0 from the final strcmp() below.
 358          *
 359          * Technically this matches "fooidx" and "foopack", but we'd never have
 360          * such names in the first place.
 361          */
 362         if (!strcmp(idx_name, "idx") && !strcmp(idx_or_pack_name, "pack"))
 363                 return 0;
 364
 365         /*
 366          * This not only checks for a complete match, but also orders based on
 367          * the first non-identical character, which means our ordering will
 368          * match a raw strcmp(). That makes it OK to use this to binary search
 369          * a naively-sorted list.
 370          */
 371         return strcmp(idx_or_pack_name, idx_name);
 372 }
 373
 374 int midx_contains_pack(struct multi_pack_index *m, const char *idx_or_pack_name)
 375 {
 376         uint32_t first = 0, last = m->num_packs;
 377
 378         while (first < last) {
 379                 uint32_t mid = first + (last - first) / 2;
 380                 const char *current;
 381                 int cmp;
 382
 383                 current = m->pack_names[mid];
 384                 cmp = cmp_idx_or_pack_name(idx_or_pack_name, current);
 385                 if (!cmp)
 386                         return 1;
 387                 if (cmp > 0) {
 388                         first = mid + 1;
 389                         continue;
 390                 }
 391                 last = mid;
 392         }
 393
 394         return 0;
 395 }
 396
 397 int prepare_multi_pack_index_one(struct repository *r, const char *object_dir, int local)
 398 {
 399         struct multi_pack_index *m;
 400         struct multi_pack_index *m_search;
 401         int config_value;
 402         static int env_value = -1;
 403
 404         if (env_value < 0)
 405                 env_value = git_env_bool(GIT_TEST_MULTI_PACK_INDEX, 0);
 406
 407         if (!env_value &&
 408             (repo_config_get_bool(r, "core.multipackindex", &config_value) ||
 409             !config_value))
 410                 return 0;
 411
 412         for (m_search = r->objects->multi_pack_index; m_search; m_search = m_search->next)
 413                 if (!strcmp(object_dir, m_search->object_dir))
 414                         return 1;
 415
 416         m = load_multi_pack_index(object_dir, local);
 417
 418         if (m) {
 419                 m->next = r->objects->multi_pack_index;
 420                 r->objects->multi_pack_index = m;
 421                 return 1;
 422         }
 423
 424         return 0;
 425 }
 426
 427 static size_t write_midx_header(struct hashfile *f,
 428                                 unsigned char num_chunks,
 429                                 uint32_t num_packs)
 430 {
 431         unsigned char byte_values[4];
 432
 433         hashwrite_be32(f, MIDX_SIGNATURE);
 434         byte_values[0] = MIDX_VERSION;
 435         byte_values[1] = oid_version();
 436         byte_values[2] = num_chunks;
 437         byte_values[3] = 0; /* unused */
 438         hashwrite(f, byte_values, sizeof(byte_values));
 439         hashwrite_be32(f, num_packs);
 440
 441         return MIDX_HEADER_SIZE;
 442 }
 443
 444 struct pack_info {
 445         uint32_t orig_pack_int_id;
 446         char *pack_name;
 447         struct packed_git *p;
 448         unsigned expired : 1;
 449 };
 450
 451 static int pack_info_compare(const void *_a, const void *_b)
 452 {
 453         struct pack_info *a = (struct pack_info *)_a;
 454         struct pack_info *b = (struct pack_info *)_b;
 455         return strcmp(a->pack_name, b->pack_name);
 456 }
 457
 458 struct pack_list {
 459         struct pack_info *info;
 460         uint32_t nr;
 461         uint32_t alloc;
 462         struct multi_pack_index *m;
 463         struct progress *progress;
 464         unsigned pack_paths_checked;
 465 };
 466
 467 static void add_pack_to_midx(const char *full_path, size_t full_path_len,
 468                              const char *file_name, void *data)
 469 {
 470         struct pack_list *packs = (struct pack_list *)data;
 471
 472         if (ends_with(file_name, ".idx")) {
 473                 display_progress(packs->progress, ++packs->pack_paths_checked);
 474                 if (packs->m && midx_contains_pack(packs->m, file_name))
 475                         return;
 476
 477                 ALLOC_GROW(packs->info, packs->nr + 1, packs->alloc);
 478
 479                 packs->info[packs->nr].p = add_packed_git(full_path,
 480                                                           full_path_len,
 481                                                           0);
 482
 483                 if (!packs->info[packs->nr].p) {
 484                         warning(_("failed to add packfile '%s'"),
 485                                 full_path);
 486                         return;
 487                 }
 488
 489                 if (open_pack_index(packs->info[packs->nr].p)) {
 490                         warning(_("failed to open pack-index '%s'"),
 491                                 full_path);
 492                         close_pack(packs->info[packs->nr].p);
 493                         FREE_AND_NULL(packs->info[packs->nr].p);
 494                         return;
 495                 }
 496
 497                 packs->info[packs->nr].pack_name = xstrdup(file_name);
 498                 packs->info[packs->nr].orig_pack_int_id = packs->nr;
 499                 packs->info[packs->nr].expired = 0;
 500                 packs->nr++;
 501         }
 502 }
 503
 504 struct pack_midx_entry {
 505         struct object_id oid;
 506         uint32_t pack_int_id;
 507         time_t pack_mtime;
 508         uint64_t offset;
 509 };
 510
 511 static int midx_oid_compare(const void *_a, const void *_b)
 512 {
 513         const struct pack_midx_entry *a = (const struct pack_midx_entry *)_a;
 514         const struct pack_midx_entry *b = (const struct pack_midx_entry *)_b;
 515         int cmp = oidcmp(&a->oid, &b->oid);
 516
 517         if (cmp)
 518                 return cmp;
 519
 520         if (a->pack_mtime > b->pack_mtime)
 521                 return -1;
 522         else if (a->pack_mtime < b->pack_mtime)
 523                 return 1;
 524
 525         return a->pack_int_id - b->pack_int_id;
 526 }
 527
 528 static int nth_midxed_pack_midx_entry(struct multi_pack_index *m,
 529                                       struct pack_midx_entry *e,
 530                                       uint32_t pos)
 531 {
 532         if (pos >= m->num_objects)
 533                 return 1;
 534
 535         nth_midxed_object_oid(&e->oid, m, pos);
 536         e->pack_int_id = nth_midxed_pack_int_id(m, pos);
 537         e->offset = nth_midxed_offset(m, pos);
 538
 539         /* consider objects in midx to be from "old" packs */
 540         e->pack_mtime = 0;
 541         return 0;
 542 }
 543
 544 static void fill_pack_entry(uint32_t pack_int_id,
 545                             struct packed_git *p,
 546                             uint32_t cur_object,
 547                             struct pack_midx_entry *entry)
 548 {
 549         if (nth_packed_object_id(&entry->oid, p, cur_object) < 0)
 550                 die(_("failed to locate object %d in packfile"), cur_object);
 551
 552         entry->pack_int_id = pack_int_id;
 553         entry->pack_mtime = p->mtime;
 554
 555         entry->offset = nth_packed_object_offset(p, cur_object);
 556 }
 557
 558 /*
 559  * It is possible to artificially get into a state where there are many
 560  * duplicate copies of objects. That can create high memory pressure if
 561  * we are to create a list of all objects before de-duplication. To reduce
 562  * this memory pressure without a significant performance drop, automatically
 563  * group objects by the first byte of their object id. Use the IDX fanout
 564  * tables to group the data, copy to a local array, then sort.
 565  *
 566  * Copy only the de-duplicated entries (selected by most-recent modified time
 567  * of a packfile containing the object).
 568  */
 569 static struct pack_midx_entry *get_sorted_entries(struct multi_pack_index *m,
 570                                                   struct pack_info *info,
 571                                                   uint32_t nr_packs,
 572                                                   uint32_t *nr_objects)
 573 {
 574         uint32_t cur_fanout, cur_pack, cur_object;
 575         uint32_t alloc_fanout, alloc_objects, total_objects = 0;
 576         struct pack_midx_entry *entries_by_fanout = NULL;
 577         struct pack_midx_entry *deduplicated_entries = NULL;
 578         uint32_t start_pack = m ? m->num_packs : 0;
 579
 580         for (cur_pack = start_pack; cur_pack < nr_packs; cur_pack++)
 581                 total_objects += info[cur_pack].p->num_objects;
 582
 583         /*
 584          * As we de-duplicate by fanout value, we expect the fanout
 585          * slices to be evenly distributed, with some noise. Hence,
 586          * allocate slightly more than one 256th.
 587          */
 588         alloc_objects = alloc_fanout = total_objects > 3200 ? total_objects / 200 : 16;
 589
 590         ALLOC_ARRAY(entries_by_fanout, alloc_fanout);
 591         ALLOC_ARRAY(deduplicated_entries, alloc_objects);
 592         *nr_objects = 0;
 593
 594         for (cur_fanout = 0; cur_fanout < 256; cur_fanout++) {
 595                 uint32_t nr_fanout = 0;
 596
 597                 if (m) {
 598                         uint32_t start = 0, end;
 599
 600                         if (cur_fanout)
 601                                 start = ntohl(m->chunk_oid_fanout[cur_fanout - 1]);
 602                         end = ntohl(m->chunk_oid_fanout[cur_fanout]);
 603
 604                         for (cur_object = start; cur_object < end; cur_object++) {
 605                                 ALLOC_GROW(entries_by_fanout, nr_fanout + 1, alloc_fanout);
 606                                 nth_midxed_pack_midx_entry(m,
 607                                                            &entries_by_fanout[nr_fanout],
 608                                                            cur_object);
 609                                 nr_fanout++;
 610                         }
 611                 }
 612
 613                 for (cur_pack = start_pack; cur_pack < nr_packs; cur_pack++) {
 614                         uint32_t start = 0, end;
 615
 616                         if (cur_fanout)
 617                                 start = get_pack_fanout(info[cur_pack].p, cur_fanout - 1);
 618                         end = get_pack_fanout(info[cur_pack].p, cur_fanout);
 619
 620                         for (cur_object = start; cur_object < end; cur_object++) {
 621                                 ALLOC_GROW(entries_by_fanout, nr_fanout + 1, alloc_fanout);
 622                                 fill_pack_entry(cur_pack, info[cur_pack].p, cur_object, &entries_by_fanout[nr_fanout]);
 623                                 nr_fanout++;
 624                         }
 625                 }
 626
 627                 QSORT(entries_by_fanout, nr_fanout, midx_oid_compare);
 628
 629                 /*
 630                  * The batch is now sorted by OID and then mtime (descending).
 631                  * Take only the first duplicate.
 632                  */
 633                 for (cur_object = 0; cur_object < nr_fanout; cur_object++) {
 634                         if (cur_object && oideq(&entries_by_fanout[cur_object - 1].oid,
 635                                                 &entries_by_fanout[cur_object].oid))
 636                                 continue;
 637
 638                         ALLOC_GROW(deduplicated_entries, *nr_objects + 1, alloc_objects);
 639                         memcpy(&deduplicated_entries[*nr_objects],
 640                                &entries_by_fanout[cur_object],
 641                                sizeof(struct pack_midx_entry));
 642                         (*nr_objects)++;
 643                 }
 644         }
 645
 646         free(entries_by_fanout);
 647         return deduplicated_entries;
 648 }
 649
 650 static size_t write_midx_pack_names(struct hashfile *f,
 651                                     struct pack_info *info,
 652                                     uint32_t num_packs)
 653 {
 654         uint32_t i;
 655         unsigned char padding[MIDX_CHUNK_ALIGNMENT];
 656         size_t written = 0;
 657
 658         for (i = 0; i < num_packs; i++) {
 659                 size_t writelen;
 660
 661                 if (info[i].expired)
 662                         continue;
 663
 664                 if (i && strcmp(info[i].pack_name, info[i - 1].pack_name) <= 0)
 665                         BUG("incorrect pack-file order: %s before %s",
 666                             info[i - 1].pack_name,
 667                             info[i].pack_name);
 668
 669                 writelen = strlen(info[i].pack_name) + 1;
 670                 hashwrite(f, info[i].pack_name, writelen);
 671                 written += writelen;
 672         }
 673
 674         /* add padding to be aligned */
 675         i = MIDX_CHUNK_ALIGNMENT - (written % MIDX_CHUNK_ALIGNMENT);
 676         if (i < MIDX_CHUNK_ALIGNMENT) {
 677                 memset(padding, 0, sizeof(padding));
 678                 hashwrite(f, padding, i);
 679                 written += i;
 680         }
 681
 682         return written;
 683 }
 684
 685 static size_t write_midx_oid_fanout(struct hashfile *f,
 686                                     struct pack_midx_entry *objects,
 687                                     uint32_t nr_objects)
 688 {
 689         struct pack_midx_entry *list = objects;
 690         struct pack_midx_entry *last = objects + nr_objects;
 691         uint32_t count = 0;
 692         uint32_t i;
 693
 694         /*
 695         * Write the first-level table (the list is sorted,
 696         * but we use a 256-entry lookup to be able to avoid
 697         * having to do eight extra binary search iterations).
 698         */
 699         for (i = 0; i < 256; i++) {
 700                 struct pack_midx_entry *next = list;
 701
 702                 while (next < last && next->oid.hash[0] == i) {
 703                         count++;
 704                         next++;
 705                 }
 706
 707                 hashwrite_be32(f, count);
 708                 list = next;
 709         }
 710
 711         return MIDX_CHUNK_FANOUT_SIZE;
 712 }
 713
 714 static size_t write_midx_oid_lookup(struct hashfile *f, unsigned char hash_len,
 715                                     struct pack_midx_entry *objects,
 716                                     uint32_t nr_objects)
 717 {
 718         struct pack_midx_entry *list = objects;
 719         uint32_t i;
 720         size_t written = 0;
 721
 722         for (i = 0; i < nr_objects; i++) {
 723                 struct pack_midx_entry *obj = list++;
 724
 725                 if (i < nr_objects - 1) {
 726                         struct pack_midx_entry *next = list;
 727                         if (oidcmp(&obj->oid, &next->oid) >= 0)
 728                                 BUG("OIDs not in order: %s >= %s",
 729                                     oid_to_hex(&obj->oid),
 730                                     oid_to_hex(&next->oid));
 731                 }
 732
 733                 hashwrite(f, obj->oid.hash, (int)hash_len);
 734                 written += hash_len;
 735         }
 736
 737         return written;
 738 }
 739
 740 static size_t write_midx_object_offsets(struct hashfile *f, int large_offset_needed,
 741                                         uint32_t *perm,
 742                                         struct pack_midx_entry *objects, uint32_t nr_objects)
 743 {
 744         struct pack_midx_entry *list = objects;
 745         uint32_t i, nr_large_offset = 0;
 746         size_t written = 0;
 747
 748         for (i = 0; i < nr_objects; i++) {
 749                 struct pack_midx_entry *obj = list++;
 750
 751                 if (perm[obj->pack_int_id] == PACK_EXPIRED)
 752                         BUG("object %s is in an expired pack with int-id %d",
 753                             oid_to_hex(&obj->oid),
 754                             obj->pack_int_id);
 755
 756                 hashwrite_be32(f, perm[obj->pack_int_id]);
 757
 758                 if (large_offset_needed && obj->offset >> 31)
 759                         hashwrite_be32(f, MIDX_LARGE_OFFSET_NEEDED | nr_large_offset++);
 760                 else if (!large_offset_needed && obj->offset >> 32)
 761                         BUG("object %s requires a large offset (%"PRIx64") but the MIDX is not writing large offsets!",
 762                             oid_to_hex(&obj->oid),
 763                             obj->offset);
 764                 else
 765                         hashwrite_be32(f, (uint32_t)obj->offset);
 766
 767                 written += MIDX_CHUNK_OFFSET_WIDTH;
 768         }
 769
 770         return written;
 771 }
 772
 773 static size_t write_midx_large_offsets(struct hashfile *f, uint32_t nr_large_offset,
 774                                        struct pack_midx_entry *objects, uint32_t nr_objects)
 775 {
 776         struct pack_midx_entry *list = objects, *end = objects + nr_objects;
 777         size_t written = 0;
 778
 779         while (nr_large_offset) {
 780                 struct pack_midx_entry *obj;
 781                 uint64_t offset;
 782
 783                 if (list >= end)
 784                         BUG("too many large-offset objects");
 785
 786                 obj = list++;
 787                 offset = obj->offset;
 788
 789                 if (!(offset >> 31))
 790                         continue;
 791
 792                 hashwrite_be32(f, offset >> 32);
 793                 hashwrite_be32(f, offset & 0xffffffffUL);
 794                 written += 2 * sizeof(uint32_t);
 795
 796                 nr_large_offset--;
 797         }
 798
 799         return written;
 800 }
 801
 802 static int write_midx_internal(const char *object_dir, struct multi_pack_index *m,
 803                                struct string_list *packs_to_drop, unsigned flags)
 804 {
 805         unsigned char cur_chunk, num_chunks = 0;
 806         char *midx_name;
 807         uint32_t i;
 808         struct hashfile *f = NULL;
 809         struct lock_file lk;
 810         struct pack_list packs;
 811         uint32_t *pack_perm = NULL;
 812         uint64_t written = 0;
 813         uint32_t chunk_ids[MIDX_MAX_CHUNKS + 1];
 814         uint64_t chunk_offsets[MIDX_MAX_CHUNKS + 1];
 815         uint32_t nr_entries, num_large_offsets = 0;
 816         struct pack_midx_entry *entries = NULL;
 817         struct progress *progress = NULL;
 818         int large_offsets_needed = 0;
 819         int pack_name_concat_len = 0;
 820         int dropped_packs = 0;
 821         int result = 0;
 822
 823         midx_name = get_midx_filename(object_dir);
 824         if (safe_create_leading_directories(midx_name))
 825                 die_errno(_("unable to create leading directories of %s"),
 826                           midx_name);
 827
 828         if (m)
 829                 packs.m = m;
 830         else
 831                 packs.m = load_multi_pack_index(object_dir, 1);
 832
 833         packs.nr = 0;
 834         packs.alloc = packs.m ? packs.m->num_packs : 16;
 835         packs.info = NULL;
 836         ALLOC_ARRAY(packs.info, packs.alloc);
 837
 838         if (packs.m) {
 839                 for (i = 0; i < packs.m->num_packs; i++) {
 840                         ALLOC_GROW(packs.info, packs.nr + 1, packs.alloc);
 841
 842                         packs.info[packs.nr].orig_pack_int_id = i;
 843                         packs.info[packs.nr].pack_name = xstrdup(packs.m->pack_names[i]);
 844                         packs.info[packs.nr].p = NULL;
 845                         packs.info[packs.nr].expired = 0;
 846                         packs.nr++;
 847                 }
 848         }
 849
 850         packs.pack_paths_checked = 0;
 851         if (flags & MIDX_PROGRESS)
 852                 packs.progress = start_progress(_("Adding packfiles to multi-pack-index"), 0);
 853         else
 854                 packs.progress = NULL;
 855
 856         for_each_file_in_pack_dir(object_dir, add_pack_to_midx, &packs);
 857         stop_progress(&packs.progress);
 858
 859         if (packs.m && packs.nr == packs.m->num_packs && !packs_to_drop)
 860                 goto cleanup;
 861
 862         entries = get_sorted_entries(packs.m, packs.info, packs.nr, &nr_entries);
 863
 864         for (i = 0; i < nr_entries; i++) {
 865                 if (entries[i].offset > 0x7fffffff)
 866                         num_large_offsets++;
 867                 if (entries[i].offset > 0xffffffff)
 868                         large_offsets_needed = 1;
 869         }
 870
 871         QSORT(packs.info, packs.nr, pack_info_compare);
 872
 873         if (packs_to_drop && packs_to_drop->nr) {
 874                 int drop_index = 0;
 875                 int missing_drops = 0;
 876
 877                 for (i = 0; i < packs.nr && drop_index < packs_to_drop->nr; i++) {
 878                         int cmp = strcmp(packs.info[i].pack_name,
 879                                          packs_to_drop->items[drop_index].string);
 880
 881                         if (!cmp) {
 882                                 drop_index++;
 883                                 packs.info[i].expired = 1;
 884                         } else if (cmp > 0) {
 885                                 error(_("did not see pack-file %s to drop"),
 886                                       packs_to_drop->items[drop_index].string);
 887                                 drop_index++;
 888                                 missing_drops++;
 889                                 i--;
 890                         } else {
 891                                 packs.info[i].expired = 0;
 892                         }
 893                 }
 894
 895                 if (missing_drops) {
 896                         result = 1;
 897                         goto cleanup;
 898                 }
 899         }
 900
 901         /*
 902          * pack_perm stores a permutation between pack-int-ids from the
 903          * previous multi-pack-index to the new one we are writing:
 904          *
 905          * pack_perm[old_id] = new_id
 906          */
 907         ALLOC_ARRAY(pack_perm, packs.nr);
 908         for (i = 0; i < packs.nr; i++) {
 909                 if (packs.info[i].expired) {
 910                         dropped_packs++;
 911                         pack_perm[packs.info[i].orig_pack_int_id] = PACK_EXPIRED;
 912                 } else {
 913                         pack_perm[packs.info[i].orig_pack_int_id] = i - dropped_packs;
 914                 }
 915         }
 916
 917         for (i = 0; i < packs.nr; i++) {
 918                 if (!packs.info[i].expired)
 919                         pack_name_concat_len += strlen(packs.info[i].pack_name) + 1;
 920         }
 921
 922         if (pack_name_concat_len % MIDX_CHUNK_ALIGNMENT)
 923                 pack_name_concat_len += MIDX_CHUNK_ALIGNMENT -
 924                                         (pack_name_concat_len % MIDX_CHUNK_ALIGNMENT);
 925
 926         hold_lock_file_for_update(&lk, midx_name, LOCK_DIE_ON_ERROR);
 927         f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
 928         FREE_AND_NULL(midx_name);
 929
 930         if (packs.m)
 931                 close_midx(packs.m);
 932
 933         cur_chunk = 0;
 934         num_chunks = large_offsets_needed ? 5 : 4;
 935
 936         if (packs.nr - dropped_packs == 0) {
 937                 error(_("no pack files to index."));
 938                 result = 1;
 939                 goto cleanup;
 940         }
 941
 942         written = write_midx_header(f, num_chunks, packs.nr - dropped_packs);
 943
 944         chunk_ids[cur_chunk] = MIDX_CHUNKID_PACKNAMES;
 945         chunk_offsets[cur_chunk] = written + (num_chunks + 1) * MIDX_CHUNKLOOKUP_WIDTH;
 946
 947         cur_chunk++;
 948         chunk_ids[cur_chunk] = MIDX_CHUNKID_OIDFANOUT;
 949         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + pack_name_concat_len;
 950
 951         cur_chunk++;
 952         chunk_ids[cur_chunk] = MIDX_CHUNKID_OIDLOOKUP;
 953         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + MIDX_CHUNK_FANOUT_SIZE;
 954
 955         cur_chunk++;
 956         chunk_ids[cur_chunk] = MIDX_CHUNKID_OBJECTOFFSETS;
 957         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + nr_entries * the_hash_algo->rawsz;
 958
 959         cur_chunk++;
 960         chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] + nr_entries * MIDX_CHUNK_OFFSET_WIDTH;
 961         if (large_offsets_needed) {
 962                 chunk_ids[cur_chunk] = MIDX_CHUNKID_LARGEOFFSETS;
 963
 964                 cur_chunk++;
 965                 chunk_offsets[cur_chunk] = chunk_offsets[cur_chunk - 1] +
 966                                            num_large_offsets * MIDX_CHUNK_LARGE_OFFSET_WIDTH;
 967         }
 968
 969         chunk_ids[cur_chunk] = 0;
 970
 971         for (i = 0; i <= num_chunks; i++) {
 972                 if (i && chunk_offsets[i] < chunk_offsets[i - 1])
 973                         BUG("incorrect chunk offsets: %"PRIu64" before %"PRIu64,
 974                             chunk_offsets[i - 1],
 975                             chunk_offsets[i]);
 976
 977                 if (chunk_offsets[i] % MIDX_CHUNK_ALIGNMENT)
 978                         BUG("chunk offset %"PRIu64" is not properly aligned",
 979                             chunk_offsets[i]);
 980
 981                 hashwrite_be32(f, chunk_ids[i]);
 982                 hashwrite_be32(f, chunk_offsets[i] >> 32);
 983                 hashwrite_be32(f, chunk_offsets[i]);
 984
 985                 written += MIDX_CHUNKLOOKUP_WIDTH;
 986         }
 987
 988         if (flags & MIDX_PROGRESS)
 989                 progress = start_progress(_("Writing chunks to multi-pack-index"),
 990                                           num_chunks);
 991         for (i = 0; i < num_chunks; i++) {
 992                 if (written != chunk_offsets[i])
 993                         BUG("incorrect chunk offset (%"PRIu64" != %"PRIu64") for chunk id %"PRIx32,
 994                             chunk_offsets[i],
 995                             written,
 996                             chunk_ids[i]);
 997
 998                 switch (chunk_ids[i]) {
 999                         case MIDX_CHUNKID_PACKNAMES:
1000                                 written += write_midx_pack_names(f, packs.info, packs.nr);
1001                                 break;
1002
1003                         case MIDX_CHUNKID_OIDFANOUT:
1004                                 written += write_midx_oid_fanout(f, entries, nr_entries);
1005                                 break;
1006
1007                         case MIDX_CHUNKID_OIDLOOKUP:
1008                                 written += write_midx_oid_lookup(f, the_hash_algo->rawsz, entries, nr_entries);
1009                                 break;
1010
1011                         case MIDX_CHUNKID_OBJECTOFFSETS:
1012                                 written += write_midx_object_offsets(f, large_offsets_needed, pack_perm, entries, nr_entries);
1013                                 break;
1014
1015                         case MIDX_CHUNKID_LARGEOFFSETS:
1016                                 written += write_midx_large_offsets(f, num_large_offsets, entries, nr_entries);
1017                                 break;
1018
1019                         default:
1020                                 BUG("trying to write unknown chunk id %"PRIx32,
1021                                     chunk_ids[i]);
1022                 }
1023
1024                 display_progress(progress, i + 1);
1025         }
1026         stop_progress(&progress);
1027
1028         if (written != chunk_offsets[num_chunks])
1029                 BUG("incorrect final offset %"PRIu64" != %"PRIu64,
1030                     written,
1031                     chunk_offsets[num_chunks]);
1032
1033         finalize_hashfile(f, NULL, CSUM_FSYNC | CSUM_HASH_IN_STREAM);
1034         commit_lock_file(&lk);
1035
1036 cleanup:
1037         for (i = 0; i < packs.nr; i++) {
1038                 if (packs.info[i].p) {
1039                         close_pack(packs.info[i].p);
1040                         free(packs.info[i].p);
1041                 }
1042                 free(packs.info[i].pack_name);
1043         }
1044
1045         free(packs.info);
1046         free(entries);
1047         free(pack_perm);
1048         free(midx_name);
1049         return result;
1050 }
1051
1052 int write_midx_file(const char *object_dir, unsigned flags)
1053 {
1054         return write_midx_internal(object_dir, NULL, NULL, flags);
1055 }
1056
1057 void clear_midx_file(struct repository *r)
1058 {
1059         char *midx = get_midx_filename(r->objects->odb->path);
1060
1061         if (r->objects && r->objects->multi_pack_index) {
1062                 close_midx(r->objects->multi_pack_index);
1063                 r->objects->multi_pack_index = NULL;
1064         }
1065
1066         if (remove_path(midx))
1067                 die(_("failed to clear multi-pack-index at %s"), midx);
1068
1069         free(midx);
1070 }
1071
1072 static int verify_midx_error;
1073
1074 static void midx_report(const char *fmt, ...)
1075 {
1076         va_list ap;
1077         verify_midx_error = 1;
1078         va_start(ap, fmt);
1079         vfprintf(stderr, fmt, ap);
1080         fprintf(stderr, "\n");
1081         va_end(ap);
1082 }
1083
1084 struct pair_pos_vs_id
1085 {
1086         uint32_t pos;
1087         uint32_t pack_int_id;
1088 };
1089
1090 static int compare_pair_pos_vs_id(const void *_a, const void *_b)
1091 {
1092         struct pair_pos_vs_id *a = (struct pair_pos_vs_id *)_a;
1093         struct pair_pos_vs_id *b = (struct pair_pos_vs_id *)_b;
1094
1095         return b->pack_int_id - a->pack_int_id;
1096 }
1097
1098 /*
1099  * Limit calls to display_progress() for performance reasons.
1100  * The interval here was arbitrarily chosen.
1101  */
1102 #define SPARSE_PROGRESS_INTERVAL (1 << 12)
1103 #define midx_display_sparse_progress(progress, n) \
1104         do { \
1105                 uint64_t _n = (n); \
1106                 if ((_n & (SPARSE_PROGRESS_INTERVAL - 1)) == 0) \
1107                         display_progress(progress, _n); \
1108         } while (0)
1109
1110 int verify_midx_file(struct repository *r, const char *object_dir, unsigned flags)
1111 {
1112         struct pair_pos_vs_id *pairs = NULL;
1113         uint32_t i;
1114         struct progress *progress = NULL;
1115         struct multi_pack_index *m = load_multi_pack_index(object_dir, 1);
1116         verify_midx_error = 0;
1117
1118         if (!m) {
1119                 int result = 0;
1120                 struct stat sb;
1121                 char *filename = get_midx_filename(object_dir);
1122                 if (!stat(filename, &sb)) {
1123                         error(_("multi-pack-index file exists, but failed to parse"));
1124                         result = 1;
1125                 }
1126                 free(filename);
1127                 return result;
1128         }
1129
1130         if (flags & MIDX_PROGRESS)
1131                 progress = start_progress(_("Looking for referenced packfiles"),
1132                                           m->num_packs);
1133         for (i = 0; i < m->num_packs; i++) {
1134                 if (prepare_midx_pack(r, m, i))
1135                         midx_report("failed to load pack in position %d", i);
1136
1137                 display_progress(progress, i + 1);
1138         }
1139         stop_progress(&progress);
1140
1141         for (i = 0; i < 255; i++) {
1142                 uint32_t oid_fanout1 = ntohl(m->chunk_oid_fanout[i]);
1143                 uint32_t oid_fanout2 = ntohl(m->chunk_oid_fanout[i + 1]);
1144
1145                 if (oid_fanout1 > oid_fanout2)
1146                         midx_report(_("oid fanout out of order: fanout[%d] = %"PRIx32" > %"PRIx32" = fanout[%d]"),
1147                                     i, oid_fanout1, oid_fanout2, i + 1);
1148         }
1149
1150         if (m->num_objects == 0) {
1151                 midx_report(_("the midx contains no oid"));
1152                 /*
1153                  * Remaining tests assume that we have objects, so we can
1154                  * return here.
1155                  */
1156                 return verify_midx_error;
1157         }
1158
1159         if (flags & MIDX_PROGRESS)
1160                 progress = start_sparse_progress(_("Verifying OID order in multi-pack-index"),
1161                                                  m->num_objects - 1);
1162         for (i = 0; i < m->num_objects - 1; i++) {
1163                 struct object_id oid1, oid2;
1164
1165                 nth_midxed_object_oid(&oid1, m, i);
1166                 nth_midxed_object_oid(&oid2, m, i + 1);
1167
1168                 if (oidcmp(&oid1, &oid2) >= 0)
1169                         midx_report(_("oid lookup out of order: oid[%d] = %s >= %s = oid[%d]"),
1170                                     i, oid_to_hex(&oid1), oid_to_hex(&oid2), i + 1);
1171
1172                 midx_display_sparse_progress(progress, i + 1);
1173         }
1174         stop_progress(&progress);
1175
1176         /*
1177          * Create an array mapping each object to its packfile id.  Sort it
1178          * to group the objects by packfile.  Use this permutation to visit
1179          * each of the objects and only require 1 packfile to be open at a
1180          * time.
1181          */
1182         ALLOC_ARRAY(pairs, m->num_objects);
1183         for (i = 0; i < m->num_objects; i++) {
1184                 pairs[i].pos = i;
1185                 pairs[i].pack_int_id = nth_midxed_pack_int_id(m, i);
1186         }
1187
1188         if (flags & MIDX_PROGRESS)
1189                 progress = start_sparse_progress(_("Sorting objects by packfile"),
1190                                                  m->num_objects);
1191         display_progress(progress, 0); /* TODO: Measure QSORT() progress */
1192         QSORT(pairs, m->num_objects, compare_pair_pos_vs_id);
1193         stop_progress(&progress);
1194
1195         if (flags & MIDX_PROGRESS)
1196                 progress = start_sparse_progress(_("Verifying object offsets"), m->num_objects);
1197         for (i = 0; i < m->num_objects; i++) {
1198                 struct object_id oid;
1199                 struct pack_entry e;
1200                 off_t m_offset, p_offset;
1201
1202                 if (i > 0 && pairs[i-1].pack_int_id != pairs[i].pack_int_id &&
1203                     m->packs[pairs[i-1].pack_int_id])
1204                 {
1205                         close_pack_fd(m->packs[pairs[i-1].pack_int_id]);
1206                         close_pack_index(m->packs[pairs[i-1].pack_int_id]);
1207                 }
1208
1209                 nth_midxed_object_oid(&oid, m, pairs[i].pos);
1210
1211                 if (!fill_midx_entry(r, &oid, &e, m)) {
1212                         midx_report(_("failed to load pack entry for oid[%d] = %s"),
1213                                     pairs[i].pos, oid_to_hex(&oid));
1214                         continue;
1215                 }
1216
1217                 if (open_pack_index(e.p)) {
1218                         midx_report(_("failed to load pack-index for packfile %s"),
1219                                     e.p->pack_name);
1220                         break;
1221                 }
1222
1223                 m_offset = e.offset;
1224                 p_offset = find_pack_entry_one(oid.hash, e.p);
1225
1226                 if (m_offset != p_offset)
1227                         midx_report(_("incorrect object offset for oid[%d] = %s: %"PRIx64" != %"PRIx64),
1228                                     pairs[i].pos, oid_to_hex(&oid), m_offset, p_offset);
1229
1230                 midx_display_sparse_progress(progress, i + 1);
1231         }
1232         stop_progress(&progress);
1233
1234         free(pairs);
1235
1236         return verify_midx_error;
1237 }
1238
1239 int expire_midx_packs(struct repository *r, const char *object_dir, unsigned flags)
1240 {
1241         uint32_t i, *count, result = 0;
1242         struct string_list packs_to_drop = STRING_LIST_INIT_DUP;
1243         struct multi_pack_index *m = load_multi_pack_index(object_dir, 1);
1244         struct progress *progress = NULL;
1245
1246         if (!m)
1247                 return 0;
1248
1249         count = xcalloc(m->num_packs, sizeof(uint32_t));
1250
1251         if (flags & MIDX_PROGRESS)
1252                 progress = start_progress(_("Counting referenced objects"),
1253                                           m->num_objects);
1254         for (i = 0; i < m->num_objects; i++) {
1255                 int pack_int_id = nth_midxed_pack_int_id(m, i);
1256                 count[pack_int_id]++;
1257                 display_progress(progress, i + 1);
1258         }
1259         stop_progress(&progress);
1260
1261         if (flags & MIDX_PROGRESS)
1262                 progress = start_progress(_("Finding and deleting unreferenced packfiles"),
1263                                           m->num_packs);
1264         for (i = 0; i < m->num_packs; i++) {
1265                 char *pack_name;
1266                 display_progress(progress, i + 1);
1267
1268                 if (count[i])
1269                         continue;
1270
1271                 if (prepare_midx_pack(r, m, i))
1272                         continue;
1273
1274                 if (m->packs[i]->pack_keep)
1275                         continue;
1276
1277                 pack_name = xstrdup(m->packs[i]->pack_name);
1278                 close_pack(m->packs[i]);
1279
1280                 string_list_insert(&packs_to_drop, m->pack_names[i]);
1281                 unlink_pack_path(pack_name, 0);
1282                 free(pack_name);
1283         }
1284         stop_progress(&progress);
1285
1286         free(count);
1287
1288         if (packs_to_drop.nr)
1289                 result = write_midx_internal(object_dir, m, &packs_to_drop, flags);
1290
1291         string_list_clear(&packs_to_drop, 0);
1292         return result;
1293 }
1294
1295 struct repack_info {
1296         timestamp_t mtime;
1297         uint32_t referenced_objects;
1298         uint32_t pack_int_id;
1299 };
1300
1301 static int compare_by_mtime(const void *a_, const void *b_)
1302 {
1303         const struct repack_info *a, *b;
1304
1305         a = (const struct repack_info *)a_;
1306         b = (const struct repack_info *)b_;
1307
1308         if (a->mtime < b->mtime)
1309                 return -1;
1310         if (a->mtime > b->mtime)
1311                 return 1;
1312         return 0;
1313 }
1314
1315 static int fill_included_packs_all(struct repository *r,
1316                                    struct multi_pack_index *m,
1317                                    unsigned char *include_pack)
1318 {
1319         uint32_t i, count = 0;
1320         int pack_kept_objects = 0;
1321
1322         repo_config_get_bool(r, "repack.packkeptobjects", &pack_kept_objects);
1323
1324         for (i = 0; i < m->num_packs; i++) {
1325                 if (prepare_midx_pack(r, m, i))
1326                         continue;
1327                 if (!pack_kept_objects && m->packs[i]->pack_keep)
1328                         continue;
1329
1330                 include_pack[i] = 1;
1331                 count++;
1332         }
1333
1334         return count < 2;
1335 }
1336
1337 static int fill_included_packs_batch(struct repository *r,
1338                                      struct multi_pack_index *m,
1339                                      unsigned char *include_pack,
1340                                      size_t batch_size)
1341 {
1342         uint32_t i, packs_to_repack;
1343         size_t total_size;
1344         struct repack_info *pack_info = xcalloc(m->num_packs, sizeof(struct repack_info));
1345         int pack_kept_objects = 0;
1346
1347         repo_config_get_bool(r, "repack.packkeptobjects", &pack_kept_objects);
1348
1349         for (i = 0; i < m->num_packs; i++) {
1350                 pack_info[i].pack_int_id = i;
1351
1352                 if (prepare_midx_pack(r, m, i))
1353                         continue;
1354
1355                 pack_info[i].mtime = m->packs[i]->mtime;
1356         }
1357
1358         for (i = 0; batch_size && i < m->num_objects; i++) {
1359                 uint32_t pack_int_id = nth_midxed_pack_int_id(m, i);
1360                 pack_info[pack_int_id].referenced_objects++;
1361         }
1362
1363         QSORT(pack_info, m->num_packs, compare_by_mtime);
1364
1365         total_size = 0;
1366         packs_to_repack = 0;
1367         for (i = 0; total_size < batch_size && i < m->num_packs; i++) {
1368                 int pack_int_id = pack_info[i].pack_int_id;
1369                 struct packed_git *p = m->packs[pack_int_id];
1370                 size_t expected_size;
1371
1372                 if (!p)
1373                         continue;
1374                 if (!pack_kept_objects && p->pack_keep)
1375                         continue;
1376                 if (open_pack_index(p) || !p->num_objects)
1377                         continue;
1378
1379                 expected_size = (size_t)(p->pack_size
1380                                          * pack_info[i].referenced_objects);
1381                 expected_size /= p->num_objects;
1382
1383                 if (expected_size >= batch_size)
1384                         continue;
1385
1386                 packs_to_repack++;
1387                 total_size += expected_size;
1388                 include_pack[pack_int_id] = 1;
1389         }
1390
1391         free(pack_info);
1392
1393         if (packs_to_repack < 2)
1394                 return 1;
1395
1396         return 0;
1397 }
1398
1399 int midx_repack(struct repository *r, const char *object_dir, size_t batch_size, unsigned flags)
1400 {
1401         int result = 0;
1402         uint32_t i;
1403         unsigned char *include_pack;
1404         struct child_process cmd = CHILD_PROCESS_INIT;
1405         FILE *cmd_in;
1406         struct strbuf base_name = STRBUF_INIT;
1407         struct multi_pack_index *m = load_multi_pack_index(object_dir, 1);
1408
1409         /*
1410          * When updating the default for these configuration
1411          * variables in builtin/repack.c, these must be adjusted
1412          * to match.
1413          */
1414         int delta_base_offset = 1;
1415         int use_delta_islands = 0;
1416
1417         if (!m)
1418                 return 0;
1419
1420         include_pack = xcalloc(m->num_packs, sizeof(unsigned char));
1421
1422         if (batch_size) {
1423                 if (fill_included_packs_batch(r, m, include_pack, batch_size))
1424                         goto cleanup;
1425         } else if (fill_included_packs_all(r, m, include_pack))
1426                 goto cleanup;
1427
1428         repo_config_get_bool(r, "repack.usedeltabaseoffset", &delta_base_offset);
1429         repo_config_get_bool(r, "repack.usedeltaislands", &use_delta_islands);
1430
1431         strvec_push(&cmd.args, "pack-objects");
1432
1433         strbuf_addstr(&base_name, object_dir);
1434         strbuf_addstr(&base_name, "/pack/pack");
1435         strvec_push(&cmd.args, base_name.buf);
1436
1437         if (delta_base_offset)
1438                 strvec_push(&cmd.args, "--delta-base-offset");
1439         if (use_delta_islands)
1440                 strvec_push(&cmd.args, "--delta-islands");
1441
1442         if (flags & MIDX_PROGRESS)
1443                 strvec_push(&cmd.args, "--progress");
1444         else
1445                 strvec_push(&cmd.args, "-q");
1446
1447         strbuf_release(&base_name);
1448
1449         cmd.git_cmd = 1;
1450         cmd.in = cmd.out = -1;
1451
1452         if (start_command(&cmd)) {
1453                 error(_("could not start pack-objects"));
1454                 result = 1;
1455                 goto cleanup;
1456         }
1457
1458         cmd_in = xfdopen(cmd.in, "w");
1459
1460         for (i = 0; i < m->num_objects; i++) {
1461                 struct object_id oid;
1462                 uint32_t pack_int_id = nth_midxed_pack_int_id(m, i);
1463
1464                 if (!include_pack[pack_int_id])
1465                         continue;
1466
1467                 nth_midxed_object_oid(&oid, m, i);
1468                 fprintf(cmd_in, "%s\n", oid_to_hex(&oid));
1469         }
1470         fclose(cmd_in);
1471
1472         if (finish_command(&cmd)) {
1473                 error(_("could not finish pack-objects"));
1474                 result = 1;
1475                 goto cleanup;
1476         }
1477
1478         result = write_midx_internal(object_dir, m, NULL, flags);
1479         m = NULL;
1480
1481 cleanup:
1482         if (m)
1483                 close_midx(m);
1484         free(include_pack);
1485         return result;
1486 }