git.oblomov.eu Git - git/blob - commit-graph.c

   1 #include "cache.h"
   2 #include "config.h"
   3 #include "git-compat-util.h"
   4 #include "lockfile.h"
   5 #include "pack.h"
   6 #include "packfile.h"
   7 #include "commit.h"
   8 #include "object.h"
   9 #include "revision.h"
  10 #include "sha1-lookup.h"
  11 #include "commit-graph.h"
  12
  13 #define GRAPH_SIGNATURE 0x43475048 /* "CGPH" */
  14 #define GRAPH_CHUNKID_OIDFANOUT 0x4f494446 /* "OIDF" */
  15 #define GRAPH_CHUNKID_OIDLOOKUP 0x4f49444c /* "OIDL" */
  16 #define GRAPH_CHUNKID_DATA 0x43444154 /* "CDAT" */
  17 #define GRAPH_CHUNKID_LARGEEDGES 0x45444745 /* "EDGE" */
  18
  19 #define GRAPH_DATA_WIDTH 36
  20
  21 #define GRAPH_VERSION_1 0x1
  22 #define GRAPH_VERSION GRAPH_VERSION_1
  23
  24 #define GRAPH_OID_VERSION_SHA1 1
  25 #define GRAPH_OID_LEN_SHA1 GIT_SHA1_RAWSZ
  26 #define GRAPH_OID_VERSION GRAPH_OID_VERSION_SHA1
  27 #define GRAPH_OID_LEN GRAPH_OID_LEN_SHA1
  28
  29 #define GRAPH_OCTOPUS_EDGES_NEEDED 0x80000000
  30 #define GRAPH_PARENT_MISSING 0x7fffffff
  31 #define GRAPH_EDGE_LAST_MASK 0x7fffffff
  32 #define GRAPH_PARENT_NONE 0x70000000
  33
  34 #define GRAPH_LAST_EDGE 0x80000000
  35
  36 #define GRAPH_FANOUT_SIZE (4 * 256)
  37 #define GRAPH_CHUNKLOOKUP_WIDTH 12
  38 #define GRAPH_MIN_SIZE (5 * GRAPH_CHUNKLOOKUP_WIDTH + GRAPH_FANOUT_SIZE + \
  39                         GRAPH_OID_LEN + 8)
  40
  41 char *get_commit_graph_filename(const char *obj_dir)
  42 {
  43         return xstrfmt("%s/info/commit-graph", obj_dir);
  44 }
  45
  46 static struct commit_graph *alloc_commit_graph(void)
  47 {
  48         struct commit_graph *g = xcalloc(1, sizeof(*g));
  49         g->graph_fd = -1;
  50
  51         return g;
  52 }
  53
  54 struct commit_graph *load_commit_graph_one(const char *graph_file)
  55 {
  56         void *graph_map;
  57         const unsigned char *data, *chunk_lookup;
  58         size_t graph_size;
  59         struct stat st;
  60         uint32_t i;
  61         struct commit_graph *graph;
  62         int fd = git_open(graph_file);
  63         uint64_t last_chunk_offset;
  64         uint32_t last_chunk_id;
  65         uint32_t graph_signature;
  66         unsigned char graph_version, hash_version;
  67
  68         if (fd < 0)
  69                 return NULL;
  70         if (fstat(fd, &st)) {
  71                 close(fd);
  72                 return NULL;
  73         }
  74         graph_size = xsize_t(st.st_size);
  75
  76         if (graph_size < GRAPH_MIN_SIZE) {
  77                 close(fd);
  78                 die("graph file %s is too small", graph_file);
  79         }
  80         graph_map = xmmap(NULL, graph_size, PROT_READ, MAP_PRIVATE, fd, 0);
  81         data = (const unsigned char *)graph_map;
  82
  83         graph_signature = get_be32(data);
  84         if (graph_signature != GRAPH_SIGNATURE) {
  85                 error("graph signature %X does not match signature %X",
  86                       graph_signature, GRAPH_SIGNATURE);
  87                 goto cleanup_fail;
  88         }
  89
  90         graph_version = *(unsigned char*)(data + 4);
  91         if (graph_version != GRAPH_VERSION) {
  92                 error("graph version %X does not match version %X",
  93                       graph_version, GRAPH_VERSION);
  94                 goto cleanup_fail;
  95         }
  96
  97         hash_version = *(unsigned char*)(data + 5);
  98         if (hash_version != GRAPH_OID_VERSION) {
  99                 error("hash version %X does not match version %X",
 100                       hash_version, GRAPH_OID_VERSION);
 101                 goto cleanup_fail;
 102         }
 103
 104         graph = alloc_commit_graph();
 105
 106         graph->hash_len = GRAPH_OID_LEN;
 107         graph->num_chunks = *(unsigned char*)(data + 6);
 108         graph->graph_fd = fd;
 109         graph->data = graph_map;
 110         graph->data_len = graph_size;
 111
 112         last_chunk_id = 0;
 113         last_chunk_offset = 8;
 114         chunk_lookup = data + 8;
 115         for (i = 0; i < graph->num_chunks; i++) {
 116                 uint32_t chunk_id = get_be32(chunk_lookup + 0);
 117                 uint64_t chunk_offset = get_be64(chunk_lookup + 4);
 118                 int chunk_repeated = 0;
 119
 120                 chunk_lookup += GRAPH_CHUNKLOOKUP_WIDTH;
 121
 122                 if (chunk_offset > graph_size - GIT_MAX_RAWSZ) {
 123                         error("improper chunk offset %08x%08x", (uint32_t)(chunk_offset >> 32),
 124                               (uint32_t)chunk_offset);
 125                         goto cleanup_fail;
 126                 }
 127
 128                 switch (chunk_id) {
 129                 case GRAPH_CHUNKID_OIDFANOUT:
 130                         if (graph->chunk_oid_fanout)
 131                                 chunk_repeated = 1;
 132                         else
 133                                 graph->chunk_oid_fanout = (uint32_t*)(data + chunk_offset);
 134                         break;
 135
 136                 case GRAPH_CHUNKID_OIDLOOKUP:
 137                         if (graph->chunk_oid_lookup)
 138                                 chunk_repeated = 1;
 139                         else
 140                                 graph->chunk_oid_lookup = data + chunk_offset;
 141                         break;
 142
 143                 case GRAPH_CHUNKID_DATA:
 144                         if (graph->chunk_commit_data)
 145                                 chunk_repeated = 1;
 146                         else
 147                                 graph->chunk_commit_data = data + chunk_offset;
 148                         break;
 149
 150                 case GRAPH_CHUNKID_LARGEEDGES:
 151                         if (graph->chunk_large_edges)
 152                                 chunk_repeated = 1;
 153                         else
 154                                 graph->chunk_large_edges = data + chunk_offset;
 155                         break;
 156                 }
 157
 158                 if (chunk_repeated) {
 159                         error("chunk id %08x appears multiple times", chunk_id);
 160                         goto cleanup_fail;
 161                 }
 162
 163                 if (last_chunk_id == GRAPH_CHUNKID_OIDLOOKUP)
 164                 {
 165                         graph->num_commits = (chunk_offset - last_chunk_offset)
 166                                              / graph->hash_len;
 167                 }
 168
 169                 last_chunk_id = chunk_id;
 170                 last_chunk_offset = chunk_offset;
 171         }
 172
 173         return graph;
 174
 175 cleanup_fail:
 176         munmap(graph_map, graph_size);
 177         close(fd);
 178         exit(1);
 179 }
 180
 181 /* global storage */
 182 static struct commit_graph *commit_graph = NULL;
 183
 184 static void prepare_commit_graph_one(const char *obj_dir)
 185 {
 186         char *graph_name;
 187
 188         if (commit_graph)
 189                 return;
 190
 191         graph_name = get_commit_graph_filename(obj_dir);
 192         commit_graph = load_commit_graph_one(graph_name);
 193
 194         FREE_AND_NULL(graph_name);
 195 }
 196
 197 static int prepare_commit_graph_run_once = 0;
 198 static void prepare_commit_graph(void)
 199 {
 200         struct alternate_object_database *alt;
 201         char *obj_dir;
 202
 203         if (prepare_commit_graph_run_once)
 204                 return;
 205         prepare_commit_graph_run_once = 1;
 206
 207         obj_dir = get_object_directory();
 208         prepare_commit_graph_one(obj_dir);
 209         prepare_alt_odb();
 210         for (alt = alt_odb_list; !commit_graph && alt; alt = alt->next)
 211                 prepare_commit_graph_one(alt->path);
 212 }
 213
 214 static void close_commit_graph(void)
 215 {
 216         if (!commit_graph)
 217                 return;
 218
 219         if (commit_graph->graph_fd >= 0) {
 220                 munmap((void *)commit_graph->data, commit_graph->data_len);
 221                 commit_graph->data = NULL;
 222                 close(commit_graph->graph_fd);
 223         }
 224
 225         FREE_AND_NULL(commit_graph);
 226 }
 227
 228 static int bsearch_graph(struct commit_graph *g, struct object_id *oid, uint32_t *pos)
 229 {
 230         return bsearch_hash(oid->hash, g->chunk_oid_fanout,
 231                             g->chunk_oid_lookup, g->hash_len, pos);
 232 }
 233
 234 static struct commit_list **insert_parent_or_die(struct commit_graph *g,
 235                                                  uint64_t pos,
 236                                                  struct commit_list **pptr)
 237 {
 238         struct commit *c;
 239         struct object_id oid;
 240         hashcpy(oid.hash, g->chunk_oid_lookup + g->hash_len * pos);
 241         c = lookup_commit(&oid);
 242         if (!c)
 243                 die("could not find commit %s", oid_to_hex(&oid));
 244         c->graph_pos = pos;
 245         return &commit_list_insert(c, pptr)->next;
 246 }
 247
 248 static void fill_commit_graph_info(struct commit *item, struct commit_graph *g, uint32_t pos)
 249 {
 250         const unsigned char *commit_data = g->chunk_commit_data + GRAPH_DATA_WIDTH * pos;
 251         item->graph_pos = pos;
 252         item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
 253 }
 254
 255 static int fill_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t pos)
 256 {
 257         uint32_t edge_value;
 258         uint32_t *parent_data_ptr;
 259         uint64_t date_low, date_high;
 260         struct commit_list **pptr;
 261         const unsigned char *commit_data = g->chunk_commit_data + (g->hash_len + 16) * pos;
 262
 263         item->object.parsed = 1;
 264         item->graph_pos = pos;
 265
 266         item->maybe_tree = NULL;
 267
 268         date_high = get_be32(commit_data + g->hash_len + 8) & 0x3;
 269         date_low = get_be32(commit_data + g->hash_len + 12);
 270         item->date = (timestamp_t)((date_high << 32) | date_low);
 271
 272         item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
 273
 274         pptr = &item->parents;
 275
 276         edge_value = get_be32(commit_data + g->hash_len);
 277         if (edge_value == GRAPH_PARENT_NONE)
 278                 return 1;
 279         pptr = insert_parent_or_die(g, edge_value, pptr);
 280
 281         edge_value = get_be32(commit_data + g->hash_len + 4);
 282         if (edge_value == GRAPH_PARENT_NONE)
 283                 return 1;
 284         if (!(edge_value & GRAPH_OCTOPUS_EDGES_NEEDED)) {
 285                 pptr = insert_parent_or_die(g, edge_value, pptr);
 286                 return 1;
 287         }
 288
 289         parent_data_ptr = (uint32_t*)(g->chunk_large_edges +
 290                           4 * (uint64_t)(edge_value & GRAPH_EDGE_LAST_MASK));
 291         do {
 292                 edge_value = get_be32(parent_data_ptr);
 293                 pptr = insert_parent_or_die(g,
 294                                             edge_value & GRAPH_EDGE_LAST_MASK,
 295                                             pptr);
 296                 parent_data_ptr++;
 297         } while (!(edge_value & GRAPH_LAST_EDGE));
 298
 299         return 1;
 300 }
 301
 302 static int find_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t *pos)
 303 {
 304         if (item->graph_pos != COMMIT_NOT_FROM_GRAPH) {
 305                 *pos = item->graph_pos;
 306                 return 1;
 307         } else {
 308                 return bsearch_graph(g, &(item->object.oid), pos);
 309         }
 310 }
 311
 312 int parse_commit_in_graph(struct commit *item)
 313 {
 314         uint32_t pos;
 315
 316         if (!core_commit_graph)
 317                 return 0;
 318         if (item->object.parsed)
 319                 return 1;
 320         prepare_commit_graph();
 321         if (commit_graph && find_commit_in_graph(item, commit_graph, &pos))
 322                 return fill_commit_in_graph(item, commit_graph, pos);
 323         return 0;
 324 }
 325
 326 void load_commit_graph_info(struct commit *item)
 327 {
 328         uint32_t pos;
 329         if (!core_commit_graph)
 330                 return;
 331         prepare_commit_graph();
 332         if (commit_graph && find_commit_in_graph(item, commit_graph, &pos))
 333                 fill_commit_graph_info(item, commit_graph, pos);
 334 }
 335
 336 static struct tree *load_tree_for_commit(struct commit_graph *g, struct commit *c)
 337 {
 338         struct object_id oid;
 339         const unsigned char *commit_data = g->chunk_commit_data +
 340                                            GRAPH_DATA_WIDTH * (c->graph_pos);
 341
 342         hashcpy(oid.hash, commit_data);
 343         c->maybe_tree = lookup_tree(&oid);
 344
 345         return c->maybe_tree;
 346 }
 347
 348 struct tree *get_commit_tree_in_graph(const struct commit *c)
 349 {
 350         if (c->maybe_tree)
 351                 return c->maybe_tree;
 352         if (c->graph_pos == COMMIT_NOT_FROM_GRAPH)
 353                 BUG("get_commit_tree_in_graph called from non-commit-graph commit");
 354
 355         return load_tree_for_commit(commit_graph, (struct commit *)c);
 356 }
 357
 358 static void write_graph_chunk_fanout(struct hashfile *f,
 359                                      struct commit **commits,
 360                                      int nr_commits)
 361 {
 362         int i, count = 0;
 363         struct commit **list = commits;
 364
 365         /*
 366          * Write the first-level table (the list is sorted,
 367          * but we use a 256-entry lookup to be able to avoid
 368          * having to do eight extra binary search iterations).
 369          */
 370         for (i = 0; i < 256; i++) {
 371                 while (count < nr_commits) {
 372                         if ((*list)->object.oid.hash[0] != i)
 373                                 break;
 374                         count++;
 375                         list++;
 376                 }
 377
 378                 hashwrite_be32(f, count);
 379         }
 380 }
 381
 382 static void write_graph_chunk_oids(struct hashfile *f, int hash_len,
 383                                    struct commit **commits, int nr_commits)
 384 {
 385         struct commit **list = commits;
 386         int count;
 387         for (count = 0; count < nr_commits; count++, list++)
 388                 hashwrite(f, (*list)->object.oid.hash, (int)hash_len);
 389 }
 390
 391 static const unsigned char *commit_to_sha1(size_t index, void *table)
 392 {
 393         struct commit **commits = table;
 394         return commits[index]->object.oid.hash;
 395 }
 396
 397 static void write_graph_chunk_data(struct hashfile *f, int hash_len,
 398                                    struct commit **commits, int nr_commits)
 399 {
 400         struct commit **list = commits;
 401         struct commit **last = commits + nr_commits;
 402         uint32_t num_extra_edges = 0;
 403
 404         while (list < last) {
 405                 struct commit_list *parent;
 406                 int edge_value;
 407                 uint32_t packedDate[2];
 408
 409                 parse_commit(*list);
 410                 hashwrite(f, get_commit_tree_oid(*list)->hash, hash_len);
 411
 412                 parent = (*list)->parents;
 413
 414                 if (!parent)
 415                         edge_value = GRAPH_PARENT_NONE;
 416                 else {
 417                         edge_value = sha1_pos(parent->item->object.oid.hash,
 418                                               commits,
 419                                               nr_commits,
 420                                               commit_to_sha1);
 421
 422                         if (edge_value < 0)
 423                                 edge_value = GRAPH_PARENT_MISSING;
 424                 }
 425
 426                 hashwrite_be32(f, edge_value);
 427
 428                 if (parent)
 429                         parent = parent->next;
 430
 431                 if (!parent)
 432                         edge_value = GRAPH_PARENT_NONE;
 433                 else if (parent->next)
 434                         edge_value = GRAPH_OCTOPUS_EDGES_NEEDED | num_extra_edges;
 435                 else {
 436                         edge_value = sha1_pos(parent->item->object.oid.hash,
 437                                               commits,
 438                                               nr_commits,
 439                                               commit_to_sha1);
 440                         if (edge_value < 0)
 441                                 edge_value = GRAPH_PARENT_MISSING;
 442                 }
 443
 444                 hashwrite_be32(f, edge_value);
 445
 446                 if (edge_value & GRAPH_OCTOPUS_EDGES_NEEDED) {
 447                         do {
 448                                 num_extra_edges++;
 449                                 parent = parent->next;
 450                         } while (parent);
 451                 }
 452
 453                 if (sizeof((*list)->date) > 4)
 454                         packedDate[0] = htonl(((*list)->date >> 32) & 0x3);
 455                 else
 456                         packedDate[0] = 0;
 457
 458                 packedDate[0] |= htonl((*list)->generation << 2);
 459
 460                 packedDate[1] = htonl((*list)->date);
 461                 hashwrite(f, packedDate, 8);
 462
 463                 list++;
 464         }
 465 }
 466
 467 static void write_graph_chunk_large_edges(struct hashfile *f,
 468                                           struct commit **commits,
 469                                           int nr_commits)
 470 {
 471         struct commit **list = commits;
 472         struct commit **last = commits + nr_commits;
 473         struct commit_list *parent;
 474
 475         while (list < last) {
 476                 int num_parents = 0;
 477                 for (parent = (*list)->parents; num_parents < 3 && parent;
 478                      parent = parent->next)
 479                         num_parents++;
 480
 481                 if (num_parents <= 2) {
 482                         list++;
 483                         continue;
 484                 }
 485
 486                 /* Since num_parents > 2, this initializer is safe. */
 487                 for (parent = (*list)->parents->next; parent; parent = parent->next) {
 488                         int edge_value = sha1_pos(parent->item->object.oid.hash,
 489                                                   commits,
 490                                                   nr_commits,
 491                                                   commit_to_sha1);
 492
 493                         if (edge_value < 0)
 494                                 edge_value = GRAPH_PARENT_MISSING;
 495                         else if (!parent->next)
 496                                 edge_value |= GRAPH_LAST_EDGE;
 497
 498                         hashwrite_be32(f, edge_value);
 499                 }
 500
 501                 list++;
 502         }
 503 }
 504
 505 static int commit_compare(const void *_a, const void *_b)
 506 {
 507         const struct object_id *a = (const struct object_id *)_a;
 508         const struct object_id *b = (const struct object_id *)_b;
 509         return oidcmp(a, b);
 510 }
 511
 512 struct packed_commit_list {
 513         struct commit **list;
 514         int nr;
 515         int alloc;
 516 };
 517
 518 struct packed_oid_list {
 519         struct object_id *list;
 520         int nr;
 521         int alloc;
 522 };
 523
 524 static int add_packed_commits(const struct object_id *oid,
 525                               struct packed_git *pack,
 526                               uint32_t pos,
 527                               void *data)
 528 {
 529         struct packed_oid_list *list = (struct packed_oid_list*)data;
 530         enum object_type type;
 531         off_t offset = nth_packed_object_offset(pack, pos);
 532         struct object_info oi = OBJECT_INFO_INIT;
 533
 534         oi.typep = &type;
 535         if (packed_object_info(pack, offset, &oi) < 0)
 536                 die("unable to get type of object %s", oid_to_hex(oid));
 537
 538         if (type != OBJ_COMMIT)
 539                 return 0;
 540
 541         ALLOC_GROW(list->list, list->nr + 1, list->alloc);
 542         oidcpy(&(list->list[list->nr]), oid);
 543         list->nr++;
 544
 545         return 0;
 546 }
 547
 548 static void add_missing_parents(struct packed_oid_list *oids, struct commit *commit)
 549 {
 550         struct commit_list *parent;
 551         for (parent = commit->parents; parent; parent = parent->next) {
 552                 if (!(parent->item->object.flags & UNINTERESTING)) {
 553                         ALLOC_GROW(oids->list, oids->nr + 1, oids->alloc);
 554                         oidcpy(&oids->list[oids->nr], &(parent->item->object.oid));
 555                         oids->nr++;
 556                         parent->item->object.flags |= UNINTERESTING;
 557                 }
 558         }
 559 }
 560
 561 static void close_reachable(struct packed_oid_list *oids)
 562 {
 563         int i;
 564         struct commit *commit;
 565
 566         for (i = 0; i < oids->nr; i++) {
 567                 commit = lookup_commit(&oids->list[i]);
 568                 if (commit)
 569                         commit->object.flags |= UNINTERESTING;
 570         }
 571
 572         /*
 573          * As this loop runs, oids->nr may grow, but not more
 574          * than the number of missing commits in the reachable
 575          * closure.
 576          */
 577         for (i = 0; i < oids->nr; i++) {
 578                 commit = lookup_commit(&oids->list[i]);
 579
 580                 if (commit && !parse_commit(commit))
 581                         add_missing_parents(oids, commit);
 582         }
 583
 584         for (i = 0; i < oids->nr; i++) {
 585                 commit = lookup_commit(&oids->list[i]);
 586
 587                 if (commit)
 588                         commit->object.flags &= ~UNINTERESTING;
 589         }
 590 }
 591
 592 static void compute_generation_numbers(struct packed_commit_list* commits)
 593 {
 594         int i;
 595         struct commit_list *list = NULL;
 596
 597         for (i = 0; i < commits->nr; i++) {
 598                 if (commits->list[i]->generation != GENERATION_NUMBER_INFINITY &&
 599                     commits->list[i]->generation != GENERATION_NUMBER_ZERO)
 600                         continue;
 601
 602                 commit_list_insert(commits->list[i], &list);
 603                 while (list) {
 604                         struct commit *current = list->item;
 605                         struct commit_list *parent;
 606                         int all_parents_computed = 1;
 607                         uint32_t max_generation = 0;
 608
 609                         for (parent = current->parents; parent; parent = parent->next) {
 610                                 if (parent->item->generation == GENERATION_NUMBER_INFINITY ||
 611                                     parent->item->generation == GENERATION_NUMBER_ZERO) {
 612                                         all_parents_computed = 0;
 613                                         commit_list_insert(parent->item, &list);
 614                                         break;
 615                                 } else if (parent->item->generation > max_generation) {
 616                                         max_generation = parent->item->generation;
 617                                 }
 618                         }
 619
 620                         if (all_parents_computed) {
 621                                 current->generation = max_generation + 1;
 622                                 pop_commit(&list);
 623
 624                                 if (current->generation > GENERATION_NUMBER_MAX)
 625                                         current->generation = GENERATION_NUMBER_MAX;
 626                         }
 627                 }
 628         }
 629 }
 630
 631 void write_commit_graph(const char *obj_dir,
 632                         const char **pack_indexes,
 633                         int nr_packs,
 634                         const char **commit_hex,
 635                         int nr_commits,
 636                         int append)
 637 {
 638         struct packed_oid_list oids;
 639         struct packed_commit_list commits;
 640         struct hashfile *f;
 641         uint32_t i, count_distinct = 0;
 642         char *graph_name;
 643         int fd;
 644         struct lock_file lk = LOCK_INIT;
 645         uint32_t chunk_ids[5];
 646         uint64_t chunk_offsets[5];
 647         int num_chunks;
 648         int num_extra_edges;
 649         struct commit_list *parent;
 650
 651         oids.nr = 0;
 652         oids.alloc = approximate_object_count() / 4;
 653
 654         if (append) {
 655                 prepare_commit_graph_one(obj_dir);
 656                 if (commit_graph)
 657                         oids.alloc += commit_graph->num_commits;
 658         }
 659
 660         if (oids.alloc < 1024)
 661                 oids.alloc = 1024;
 662         ALLOC_ARRAY(oids.list, oids.alloc);
 663
 664         if (append && commit_graph) {
 665                 for (i = 0; i < commit_graph->num_commits; i++) {
 666                         const unsigned char *hash = commit_graph->chunk_oid_lookup +
 667                                 commit_graph->hash_len * i;
 668                         hashcpy(oids.list[oids.nr++].hash, hash);
 669                 }
 670         }
 671
 672         if (pack_indexes) {
 673                 struct strbuf packname = STRBUF_INIT;
 674                 int dirlen;
 675                 strbuf_addf(&packname, "%s/pack/", obj_dir);
 676                 dirlen = packname.len;
 677                 for (i = 0; i < nr_packs; i++) {
 678                         struct packed_git *p;
 679                         strbuf_setlen(&packname, dirlen);
 680                         strbuf_addstr(&packname, pack_indexes[i]);
 681                         p = add_packed_git(packname.buf, packname.len, 1);
 682                         if (!p)
 683                                 die("error adding pack %s", packname.buf);
 684                         if (open_pack_index(p))
 685                                 die("error opening index for %s", packname.buf);
 686                         for_each_object_in_pack(p, add_packed_commits, &oids);
 687                         close_pack(p);
 688                 }
 689                 strbuf_release(&packname);
 690         }
 691
 692         if (commit_hex) {
 693                 for (i = 0; i < nr_commits; i++) {
 694                         const char *end;
 695                         struct object_id oid;
 696                         struct commit *result;
 697
 698                         if (commit_hex[i] && parse_oid_hex(commit_hex[i], &oid, &end))
 699                                 continue;
 700
 701                         result = lookup_commit_reference_gently(&oid, 1);
 702
 703                         if (result) {
 704                                 ALLOC_GROW(oids.list, oids.nr + 1, oids.alloc);
 705                                 oidcpy(&oids.list[oids.nr], &(result->object.oid));
 706                                 oids.nr++;
 707                         }
 708                 }
 709         }
 710
 711         if (!pack_indexes && !commit_hex)
 712                 for_each_packed_object(add_packed_commits, &oids, 0);
 713
 714         close_reachable(&oids);
 715
 716         QSORT(oids.list, oids.nr, commit_compare);
 717
 718         count_distinct = 1;
 719         for (i = 1; i < oids.nr; i++) {
 720                 if (oidcmp(&oids.list[i-1], &oids.list[i]))
 721                         count_distinct++;
 722         }
 723
 724         if (count_distinct >= GRAPH_PARENT_MISSING)
 725                 die(_("the commit graph format cannot write %d commits"), count_distinct);
 726
 727         commits.nr = 0;
 728         commits.alloc = count_distinct;
 729         ALLOC_ARRAY(commits.list, commits.alloc);
 730
 731         num_extra_edges = 0;
 732         for (i = 0; i < oids.nr; i++) {
 733                 int num_parents = 0;
 734                 if (i > 0 && !oidcmp(&oids.list[i-1], &oids.list[i]))
 735                         continue;
 736
 737                 commits.list[commits.nr] = lookup_commit(&oids.list[i]);
 738                 parse_commit(commits.list[commits.nr]);
 739
 740                 for (parent = commits.list[commits.nr]->parents;
 741                      parent; parent = parent->next)
 742                         num_parents++;
 743
 744                 if (num_parents > 2)
 745                         num_extra_edges += num_parents - 1;
 746
 747                 commits.nr++;
 748         }
 749         num_chunks = num_extra_edges ? 4 : 3;
 750
 751         if (commits.nr >= GRAPH_PARENT_MISSING)
 752                 die(_("too many commits to write graph"));
 753
 754         compute_generation_numbers(&commits);
 755
 756         graph_name = get_commit_graph_filename(obj_dir);
 757         fd = hold_lock_file_for_update(&lk, graph_name, 0);
 758
 759         if (fd < 0) {
 760                 struct strbuf folder = STRBUF_INIT;
 761                 strbuf_addstr(&folder, graph_name);
 762                 strbuf_setlen(&folder, strrchr(folder.buf, '/') - folder.buf);
 763
 764                 if (mkdir(folder.buf, 0777) < 0)
 765                         die_errno(_("cannot mkdir %s"), folder.buf);
 766                 strbuf_release(&folder);
 767
 768                 fd = hold_lock_file_for_update(&lk, graph_name, LOCK_DIE_ON_ERROR);
 769
 770                 if (fd < 0)
 771                         die_errno("unable to create '%s'", graph_name);
 772         }
 773
 774         f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
 775
 776         hashwrite_be32(f, GRAPH_SIGNATURE);
 777
 778         hashwrite_u8(f, GRAPH_VERSION);
 779         hashwrite_u8(f, GRAPH_OID_VERSION);
 780         hashwrite_u8(f, num_chunks);
 781         hashwrite_u8(f, 0); /* unused padding byte */
 782
 783         chunk_ids[0] = GRAPH_CHUNKID_OIDFANOUT;
 784         chunk_ids[1] = GRAPH_CHUNKID_OIDLOOKUP;
 785         chunk_ids[2] = GRAPH_CHUNKID_DATA;
 786         if (num_extra_edges)
 787                 chunk_ids[3] = GRAPH_CHUNKID_LARGEEDGES;
 788         else
 789                 chunk_ids[3] = 0;
 790         chunk_ids[4] = 0;
 791
 792         chunk_offsets[0] = 8 + (num_chunks + 1) * GRAPH_CHUNKLOOKUP_WIDTH;
 793         chunk_offsets[1] = chunk_offsets[0] + GRAPH_FANOUT_SIZE;
 794         chunk_offsets[2] = chunk_offsets[1] + GRAPH_OID_LEN * commits.nr;
 795         chunk_offsets[3] = chunk_offsets[2] + (GRAPH_OID_LEN + 16) * commits.nr;
 796         chunk_offsets[4] = chunk_offsets[3] + 4 * num_extra_edges;
 797
 798         for (i = 0; i <= num_chunks; i++) {
 799                 uint32_t chunk_write[3];
 800
 801                 chunk_write[0] = htonl(chunk_ids[i]);
 802                 chunk_write[1] = htonl(chunk_offsets[i] >> 32);
 803                 chunk_write[2] = htonl(chunk_offsets[i] & 0xffffffff);
 804                 hashwrite(f, chunk_write, 12);
 805         }
 806
 807         write_graph_chunk_fanout(f, commits.list, commits.nr);
 808         write_graph_chunk_oids(f, GRAPH_OID_LEN, commits.list, commits.nr);
 809         write_graph_chunk_data(f, GRAPH_OID_LEN, commits.list, commits.nr);
 810         write_graph_chunk_large_edges(f, commits.list, commits.nr);
 811
 812         close_commit_graph();
 813         finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_FSYNC);
 814         commit_lock_file(&lk);
 815
 816         free(oids.list);
 817         oids.alloc = 0;
 818         oids.nr = 0;
 819 }