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