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

   1 #include "cache.h"
   2 #include "config.h"
   3 #include "dir.h"
   4 #include "git-compat-util.h"
   5 #include "lockfile.h"
   6 #include "pack.h"
   7 #include "packfile.h"
   8 #include "commit.h"
   9 #include "object.h"
  10 #include "refs.h"
  11 #include "revision.h"
  12 #include "sha1-lookup.h"
  13 #include "commit-graph.h"
  14 #include "object-store.h"
  15 #include "alloc.h"
  16 #include "hashmap.h"
  17 #include "replace-object.h"
  18
  19 #define GRAPH_SIGNATURE 0x43475048 /* "CGPH" */
  20 #define GRAPH_CHUNKID_OIDFANOUT 0x4f494446 /* "OIDF" */
  21 #define GRAPH_CHUNKID_OIDLOOKUP 0x4f49444c /* "OIDL" */
  22 #define GRAPH_CHUNKID_DATA 0x43444154 /* "CDAT" */
  23 #define GRAPH_CHUNKID_LARGEEDGES 0x45444745 /* "EDGE" */
  24
  25 #define GRAPH_DATA_WIDTH 36
  26
  27 #define GRAPH_VERSION_1 0x1
  28 #define GRAPH_VERSION GRAPH_VERSION_1
  29
  30 #define GRAPH_OID_VERSION_SHA1 1
  31 #define GRAPH_OID_LEN_SHA1 GIT_SHA1_RAWSZ
  32 #define GRAPH_OID_VERSION GRAPH_OID_VERSION_SHA1
  33 #define GRAPH_OID_LEN GRAPH_OID_LEN_SHA1
  34
  35 #define GRAPH_OCTOPUS_EDGES_NEEDED 0x80000000
  36 #define GRAPH_PARENT_MISSING 0x7fffffff
  37 #define GRAPH_EDGE_LAST_MASK 0x7fffffff
  38 #define GRAPH_PARENT_NONE 0x70000000
  39
  40 #define GRAPH_LAST_EDGE 0x80000000
  41
  42 #define GRAPH_HEADER_SIZE 8
  43 #define GRAPH_FANOUT_SIZE (4 * 256)
  44 #define GRAPH_CHUNKLOOKUP_WIDTH 12
  45 #define GRAPH_MIN_SIZE (GRAPH_HEADER_SIZE + 4 * GRAPH_CHUNKLOOKUP_WIDTH \
  46                         + GRAPH_FANOUT_SIZE + GRAPH_OID_LEN)
  47
  48 char *get_commit_graph_filename(const char *obj_dir)
  49 {
  50         return xstrfmt("%s/info/commit-graph", obj_dir);
  51 }
  52
  53 static struct commit_graph *alloc_commit_graph(void)
  54 {
  55         struct commit_graph *g = xcalloc(1, sizeof(*g));
  56         g->graph_fd = -1;
  57
  58         return g;
  59 }
  60
  61 extern int read_replace_refs;
  62
  63 static int commit_graph_compatible(struct repository *r)
  64 {
  65         if (!r->gitdir)
  66                 return 0;
  67
  68         if (read_replace_refs) {
  69                 prepare_replace_object(r);
  70                 if (hashmap_get_size(&r->objects->replace_map->map))
  71                         return 0;
  72         }
  73
  74         prepare_commit_graft(r);
  75         if (r->parsed_objects && r->parsed_objects->grafts_nr)
  76                 return 0;
  77         if (is_repository_shallow(r))
  78                 return 0;
  79
  80         return 1;
  81 }
  82
  83 struct commit_graph *load_commit_graph_one(const char *graph_file)
  84 {
  85         void *graph_map;
  86         const unsigned char *data, *chunk_lookup;
  87         size_t graph_size;
  88         struct stat st;
  89         uint32_t i;
  90         struct commit_graph *graph;
  91         int fd = git_open(graph_file);
  92         uint64_t last_chunk_offset;
  93         uint32_t last_chunk_id;
  94         uint32_t graph_signature;
  95         unsigned char graph_version, hash_version;
  96
  97         if (fd < 0)
  98                 return NULL;
  99         if (fstat(fd, &st)) {
 100                 close(fd);
 101                 return NULL;
 102         }
 103         graph_size = xsize_t(st.st_size);
 104
 105         if (graph_size < GRAPH_MIN_SIZE) {
 106                 close(fd);
 107                 die("graph file %s is too small", graph_file);
 108         }
 109         graph_map = xmmap(NULL, graph_size, PROT_READ, MAP_PRIVATE, fd, 0);
 110         data = (const unsigned char *)graph_map;
 111
 112         graph_signature = get_be32(data);
 113         if (graph_signature != GRAPH_SIGNATURE) {
 114                 error("graph signature %X does not match signature %X",
 115                       graph_signature, GRAPH_SIGNATURE);
 116                 goto cleanup_fail;
 117         }
 118
 119         graph_version = *(unsigned char*)(data + 4);
 120         if (graph_version != GRAPH_VERSION) {
 121                 error("graph version %X does not match version %X",
 122                       graph_version, GRAPH_VERSION);
 123                 goto cleanup_fail;
 124         }
 125
 126         hash_version = *(unsigned char*)(data + 5);
 127         if (hash_version != GRAPH_OID_VERSION) {
 128                 error("hash version %X does not match version %X",
 129                       hash_version, GRAPH_OID_VERSION);
 130                 goto cleanup_fail;
 131         }
 132
 133         graph = alloc_commit_graph();
 134
 135         graph->hash_len = GRAPH_OID_LEN;
 136         graph->num_chunks = *(unsigned char*)(data + 6);
 137         graph->graph_fd = fd;
 138         graph->data = graph_map;
 139         graph->data_len = graph_size;
 140
 141         last_chunk_id = 0;
 142         last_chunk_offset = 8;
 143         chunk_lookup = data + 8;
 144         for (i = 0; i < graph->num_chunks; i++) {
 145                 uint32_t chunk_id = get_be32(chunk_lookup + 0);
 146                 uint64_t chunk_offset = get_be64(chunk_lookup + 4);
 147                 int chunk_repeated = 0;
 148
 149                 chunk_lookup += GRAPH_CHUNKLOOKUP_WIDTH;
 150
 151                 if (chunk_offset > graph_size - GIT_MAX_RAWSZ) {
 152                         error("improper chunk offset %08x%08x", (uint32_t)(chunk_offset >> 32),
 153                               (uint32_t)chunk_offset);
 154                         goto cleanup_fail;
 155                 }
 156
 157                 switch (chunk_id) {
 158                 case GRAPH_CHUNKID_OIDFANOUT:
 159                         if (graph->chunk_oid_fanout)
 160                                 chunk_repeated = 1;
 161                         else
 162                                 graph->chunk_oid_fanout = (uint32_t*)(data + chunk_offset);
 163                         break;
 164
 165                 case GRAPH_CHUNKID_OIDLOOKUP:
 166                         if (graph->chunk_oid_lookup)
 167                                 chunk_repeated = 1;
 168                         else
 169                                 graph->chunk_oid_lookup = data + chunk_offset;
 170                         break;
 171
 172                 case GRAPH_CHUNKID_DATA:
 173                         if (graph->chunk_commit_data)
 174                                 chunk_repeated = 1;
 175                         else
 176                                 graph->chunk_commit_data = data + chunk_offset;
 177                         break;
 178
 179                 case GRAPH_CHUNKID_LARGEEDGES:
 180                         if (graph->chunk_large_edges)
 181                                 chunk_repeated = 1;
 182                         else
 183                                 graph->chunk_large_edges = data + chunk_offset;
 184                         break;
 185                 }
 186
 187                 if (chunk_repeated) {
 188                         error("chunk id %08x appears multiple times", chunk_id);
 189                         goto cleanup_fail;
 190                 }
 191
 192                 if (last_chunk_id == GRAPH_CHUNKID_OIDLOOKUP)
 193                 {
 194                         graph->num_commits = (chunk_offset - last_chunk_offset)
 195                                              / graph->hash_len;
 196                 }
 197
 198                 last_chunk_id = chunk_id;
 199                 last_chunk_offset = chunk_offset;
 200         }
 201
 202         return graph;
 203
 204 cleanup_fail:
 205         munmap(graph_map, graph_size);
 206         close(fd);
 207         exit(1);
 208 }
 209
 210 static void prepare_commit_graph_one(struct repository *r, const char *obj_dir)
 211 {
 212         char *graph_name;
 213
 214         if (r->objects->commit_graph)
 215                 return;
 216
 217         graph_name = get_commit_graph_filename(obj_dir);
 218         r->objects->commit_graph =
 219                 load_commit_graph_one(graph_name);
 220
 221         FREE_AND_NULL(graph_name);
 222 }
 223
 224 /*
 225  * Return 1 if commit_graph is non-NULL, and 0 otherwise.
 226  *
 227  * On the first invocation, this function attemps to load the commit
 228  * graph if the_repository is configured to have one.
 229  */
 230 static int prepare_commit_graph(struct repository *r)
 231 {
 232         struct alternate_object_database *alt;
 233         char *obj_dir;
 234         int config_value;
 235
 236         if (r->objects->commit_graph_attempted)
 237                 return !!r->objects->commit_graph;
 238         r->objects->commit_graph_attempted = 1;
 239
 240         if (repo_config_get_bool(r, "core.commitgraph", &config_value) ||
 241             !config_value)
 242                 /*
 243                  * This repository is not configured to use commit graphs, so
 244                  * do not load one. (But report commit_graph_attempted anyway
 245                  * so that commit graph loading is not attempted again for this
 246                  * repository.)
 247                  */
 248                 return 0;
 249
 250         if (!commit_graph_compatible(r))
 251                 return 0;
 252
 253         obj_dir = r->objects->objectdir;
 254         prepare_commit_graph_one(r, obj_dir);
 255         prepare_alt_odb(r);
 256         for (alt = r->objects->alt_odb_list;
 257              !r->objects->commit_graph && alt;
 258              alt = alt->next)
 259                 prepare_commit_graph_one(r, alt->path);
 260         return !!r->objects->commit_graph;
 261 }
 262
 263 static void close_commit_graph(void)
 264 {
 265         free_commit_graph(the_repository->objects->commit_graph);
 266         the_repository->objects->commit_graph = NULL;
 267 }
 268
 269 static int bsearch_graph(struct commit_graph *g, struct object_id *oid, uint32_t *pos)
 270 {
 271         return bsearch_hash(oid->hash, g->chunk_oid_fanout,
 272                             g->chunk_oid_lookup, g->hash_len, pos);
 273 }
 274
 275 static struct commit_list **insert_parent_or_die(struct commit_graph *g,
 276                                                  uint64_t pos,
 277                                                  struct commit_list **pptr)
 278 {
 279         struct commit *c;
 280         struct object_id oid;
 281
 282         if (pos >= g->num_commits)
 283                 die("invalid parent position %"PRIu64, pos);
 284
 285         hashcpy(oid.hash, g->chunk_oid_lookup + g->hash_len * pos);
 286         c = lookup_commit(the_repository, &oid);
 287         if (!c)
 288                 die("could not find commit %s", oid_to_hex(&oid));
 289         c->graph_pos = pos;
 290         return &commit_list_insert(c, pptr)->next;
 291 }
 292
 293 static void fill_commit_graph_info(struct commit *item, struct commit_graph *g, uint32_t pos)
 294 {
 295         const unsigned char *commit_data = g->chunk_commit_data + GRAPH_DATA_WIDTH * pos;
 296         item->graph_pos = pos;
 297         item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
 298 }
 299
 300 static int fill_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t pos)
 301 {
 302         uint32_t edge_value;
 303         uint32_t *parent_data_ptr;
 304         uint64_t date_low, date_high;
 305         struct commit_list **pptr;
 306         const unsigned char *commit_data = g->chunk_commit_data + (g->hash_len + 16) * pos;
 307
 308         item->object.parsed = 1;
 309         item->graph_pos = pos;
 310
 311         item->maybe_tree = NULL;
 312
 313         date_high = get_be32(commit_data + g->hash_len + 8) & 0x3;
 314         date_low = get_be32(commit_data + g->hash_len + 12);
 315         item->date = (timestamp_t)((date_high << 32) | date_low);
 316
 317         item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
 318
 319         pptr = &item->parents;
 320
 321         edge_value = get_be32(commit_data + g->hash_len);
 322         if (edge_value == GRAPH_PARENT_NONE)
 323                 return 1;
 324         pptr = insert_parent_or_die(g, edge_value, pptr);
 325
 326         edge_value = get_be32(commit_data + g->hash_len + 4);
 327         if (edge_value == GRAPH_PARENT_NONE)
 328                 return 1;
 329         if (!(edge_value & GRAPH_OCTOPUS_EDGES_NEEDED)) {
 330                 pptr = insert_parent_or_die(g, edge_value, pptr);
 331                 return 1;
 332         }
 333
 334         parent_data_ptr = (uint32_t*)(g->chunk_large_edges +
 335                           4 * (uint64_t)(edge_value & GRAPH_EDGE_LAST_MASK));
 336         do {
 337                 edge_value = get_be32(parent_data_ptr);
 338                 pptr = insert_parent_or_die(g,
 339                                             edge_value & GRAPH_EDGE_LAST_MASK,
 340                                             pptr);
 341                 parent_data_ptr++;
 342         } while (!(edge_value & GRAPH_LAST_EDGE));
 343
 344         return 1;
 345 }
 346
 347 static int find_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t *pos)
 348 {
 349         if (item->graph_pos != COMMIT_NOT_FROM_GRAPH) {
 350                 *pos = item->graph_pos;
 351                 return 1;
 352         } else {
 353                 return bsearch_graph(g, &(item->object.oid), pos);
 354         }
 355 }
 356
 357 static int parse_commit_in_graph_one(struct commit_graph *g, struct commit *item)
 358 {
 359         uint32_t pos;
 360
 361         if (item->object.parsed)
 362                 return 1;
 363
 364         if (find_commit_in_graph(item, g, &pos))
 365                 return fill_commit_in_graph(item, g, pos);
 366
 367         return 0;
 368 }
 369
 370 int parse_commit_in_graph(struct repository *r, struct commit *item)
 371 {
 372         if (!prepare_commit_graph(r))
 373                 return 0;
 374         return parse_commit_in_graph_one(r->objects->commit_graph, item);
 375 }
 376
 377 void load_commit_graph_info(struct repository *r, struct commit *item)
 378 {
 379         uint32_t pos;
 380         if (!prepare_commit_graph(r))
 381                 return;
 382         if (find_commit_in_graph(item, r->objects->commit_graph, &pos))
 383                 fill_commit_graph_info(item, r->objects->commit_graph, pos);
 384 }
 385
 386 static struct tree *load_tree_for_commit(struct commit_graph *g, struct commit *c)
 387 {
 388         struct object_id oid;
 389         const unsigned char *commit_data = g->chunk_commit_data +
 390                                            GRAPH_DATA_WIDTH * (c->graph_pos);
 391
 392         hashcpy(oid.hash, commit_data);
 393         c->maybe_tree = lookup_tree(the_repository, &oid);
 394
 395         return c->maybe_tree;
 396 }
 397
 398 static struct tree *get_commit_tree_in_graph_one(struct commit_graph *g,
 399                                                  const struct commit *c)
 400 {
 401         if (c->maybe_tree)
 402                 return c->maybe_tree;
 403         if (c->graph_pos == COMMIT_NOT_FROM_GRAPH)
 404                 BUG("get_commit_tree_in_graph_one called from non-commit-graph commit");
 405
 406         return load_tree_for_commit(g, (struct commit *)c);
 407 }
 408
 409 struct tree *get_commit_tree_in_graph(struct repository *r, const struct commit *c)
 410 {
 411         return get_commit_tree_in_graph_one(r->objects->commit_graph, c);
 412 }
 413
 414 static void write_graph_chunk_fanout(struct hashfile *f,
 415                                      struct commit **commits,
 416                                      int nr_commits)
 417 {
 418         int i, count = 0;
 419         struct commit **list = commits;
 420
 421         /*
 422          * Write the first-level table (the list is sorted,
 423          * but we use a 256-entry lookup to be able to avoid
 424          * having to do eight extra binary search iterations).
 425          */
 426         for (i = 0; i < 256; i++) {
 427                 while (count < nr_commits) {
 428                         if ((*list)->object.oid.hash[0] != i)
 429                                 break;
 430                         count++;
 431                         list++;
 432                 }
 433
 434                 hashwrite_be32(f, count);
 435         }
 436 }
 437
 438 static void write_graph_chunk_oids(struct hashfile *f, int hash_len,
 439                                    struct commit **commits, int nr_commits)
 440 {
 441         struct commit **list = commits;
 442         int count;
 443         for (count = 0; count < nr_commits; count++, list++)
 444                 hashwrite(f, (*list)->object.oid.hash, (int)hash_len);
 445 }
 446
 447 static const unsigned char *commit_to_sha1(size_t index, void *table)
 448 {
 449         struct commit **commits = table;
 450         return commits[index]->object.oid.hash;
 451 }
 452
 453 static void write_graph_chunk_data(struct hashfile *f, int hash_len,
 454                                    struct commit **commits, int nr_commits)
 455 {
 456         struct commit **list = commits;
 457         struct commit **last = commits + nr_commits;
 458         uint32_t num_extra_edges = 0;
 459
 460         while (list < last) {
 461                 struct commit_list *parent;
 462                 int edge_value;
 463                 uint32_t packedDate[2];
 464
 465                 parse_commit(*list);
 466                 hashwrite(f, get_commit_tree_oid(*list)->hash, hash_len);
 467
 468                 parent = (*list)->parents;
 469
 470                 if (!parent)
 471                         edge_value = GRAPH_PARENT_NONE;
 472                 else {
 473                         edge_value = sha1_pos(parent->item->object.oid.hash,
 474                                               commits,
 475                                               nr_commits,
 476                                               commit_to_sha1);
 477
 478                         if (edge_value < 0)
 479                                 edge_value = GRAPH_PARENT_MISSING;
 480                 }
 481
 482                 hashwrite_be32(f, edge_value);
 483
 484                 if (parent)
 485                         parent = parent->next;
 486
 487                 if (!parent)
 488                         edge_value = GRAPH_PARENT_NONE;
 489                 else if (parent->next)
 490                         edge_value = GRAPH_OCTOPUS_EDGES_NEEDED | num_extra_edges;
 491                 else {
 492                         edge_value = sha1_pos(parent->item->object.oid.hash,
 493                                               commits,
 494                                               nr_commits,
 495                                               commit_to_sha1);
 496                         if (edge_value < 0)
 497                                 edge_value = GRAPH_PARENT_MISSING;
 498                 }
 499
 500                 hashwrite_be32(f, edge_value);
 501
 502                 if (edge_value & GRAPH_OCTOPUS_EDGES_NEEDED) {
 503                         do {
 504                                 num_extra_edges++;
 505                                 parent = parent->next;
 506                         } while (parent);
 507                 }
 508
 509                 if (sizeof((*list)->date) > 4)
 510                         packedDate[0] = htonl(((*list)->date >> 32) & 0x3);
 511                 else
 512                         packedDate[0] = 0;
 513
 514                 packedDate[0] |= htonl((*list)->generation << 2);
 515
 516                 packedDate[1] = htonl((*list)->date);
 517                 hashwrite(f, packedDate, 8);
 518
 519                 list++;
 520         }
 521 }
 522
 523 static void write_graph_chunk_large_edges(struct hashfile *f,
 524                                           struct commit **commits,
 525                                           int nr_commits)
 526 {
 527         struct commit **list = commits;
 528         struct commit **last = commits + nr_commits;
 529         struct commit_list *parent;
 530
 531         while (list < last) {
 532                 int num_parents = 0;
 533                 for (parent = (*list)->parents; num_parents < 3 && parent;
 534                      parent = parent->next)
 535                         num_parents++;
 536
 537                 if (num_parents <= 2) {
 538                         list++;
 539                         continue;
 540                 }
 541
 542                 /* Since num_parents > 2, this initializer is safe. */
 543                 for (parent = (*list)->parents->next; parent; parent = parent->next) {
 544                         int edge_value = sha1_pos(parent->item->object.oid.hash,
 545                                                   commits,
 546                                                   nr_commits,
 547                                                   commit_to_sha1);
 548
 549                         if (edge_value < 0)
 550                                 edge_value = GRAPH_PARENT_MISSING;
 551                         else if (!parent->next)
 552                                 edge_value |= GRAPH_LAST_EDGE;
 553
 554                         hashwrite_be32(f, edge_value);
 555                 }
 556
 557                 list++;
 558         }
 559 }
 560
 561 static int commit_compare(const void *_a, const void *_b)
 562 {
 563         const struct object_id *a = (const struct object_id *)_a;
 564         const struct object_id *b = (const struct object_id *)_b;
 565         return oidcmp(a, b);
 566 }
 567
 568 struct packed_commit_list {
 569         struct commit **list;
 570         int nr;
 571         int alloc;
 572 };
 573
 574 struct packed_oid_list {
 575         struct object_id *list;
 576         int nr;
 577         int alloc;
 578 };
 579
 580 static int add_packed_commits(const struct object_id *oid,
 581                               struct packed_git *pack,
 582                               uint32_t pos,
 583                               void *data)
 584 {
 585         struct packed_oid_list *list = (struct packed_oid_list*)data;
 586         enum object_type type;
 587         off_t offset = nth_packed_object_offset(pack, pos);
 588         struct object_info oi = OBJECT_INFO_INIT;
 589
 590         oi.typep = &type;
 591         if (packed_object_info(the_repository, pack, offset, &oi) < 0)
 592                 die("unable to get type of object %s", oid_to_hex(oid));
 593
 594         if (type != OBJ_COMMIT)
 595                 return 0;
 596
 597         ALLOC_GROW(list->list, list->nr + 1, list->alloc);
 598         oidcpy(&(list->list[list->nr]), oid);
 599         list->nr++;
 600
 601         return 0;
 602 }
 603
 604 static void add_missing_parents(struct packed_oid_list *oids, struct commit *commit)
 605 {
 606         struct commit_list *parent;
 607         for (parent = commit->parents; parent; parent = parent->next) {
 608                 if (!(parent->item->object.flags & UNINTERESTING)) {
 609                         ALLOC_GROW(oids->list, oids->nr + 1, oids->alloc);
 610                         oidcpy(&oids->list[oids->nr], &(parent->item->object.oid));
 611                         oids->nr++;
 612                         parent->item->object.flags |= UNINTERESTING;
 613                 }
 614         }
 615 }
 616
 617 static void close_reachable(struct packed_oid_list *oids)
 618 {
 619         int i;
 620         struct commit *commit;
 621
 622         for (i = 0; i < oids->nr; i++) {
 623                 commit = lookup_commit(the_repository, &oids->list[i]);
 624                 if (commit)
 625                         commit->object.flags |= UNINTERESTING;
 626         }
 627
 628         /*
 629          * As this loop runs, oids->nr may grow, but not more
 630          * than the number of missing commits in the reachable
 631          * closure.
 632          */
 633         for (i = 0; i < oids->nr; i++) {
 634                 commit = lookup_commit(the_repository, &oids->list[i]);
 635
 636                 if (commit && !parse_commit(commit))
 637                         add_missing_parents(oids, commit);
 638         }
 639
 640         for (i = 0; i < oids->nr; i++) {
 641                 commit = lookup_commit(the_repository, &oids->list[i]);
 642
 643                 if (commit)
 644                         commit->object.flags &= ~UNINTERESTING;
 645         }
 646 }
 647
 648 static void compute_generation_numbers(struct packed_commit_list* commits)
 649 {
 650         int i;
 651         struct commit_list *list = NULL;
 652
 653         for (i = 0; i < commits->nr; i++) {
 654                 if (commits->list[i]->generation != GENERATION_NUMBER_INFINITY &&
 655                     commits->list[i]->generation != GENERATION_NUMBER_ZERO)
 656                         continue;
 657
 658                 commit_list_insert(commits->list[i], &list);
 659                 while (list) {
 660                         struct commit *current = list->item;
 661                         struct commit_list *parent;
 662                         int all_parents_computed = 1;
 663                         uint32_t max_generation = 0;
 664
 665                         for (parent = current->parents; parent; parent = parent->next) {
 666                                 if (parent->item->generation == GENERATION_NUMBER_INFINITY ||
 667                                     parent->item->generation == GENERATION_NUMBER_ZERO) {
 668                                         all_parents_computed = 0;
 669                                         commit_list_insert(parent->item, &list);
 670                                         break;
 671                                 } else if (parent->item->generation > max_generation) {
 672                                         max_generation = parent->item->generation;
 673                                 }
 674                         }
 675
 676                         if (all_parents_computed) {
 677                                 current->generation = max_generation + 1;
 678                                 pop_commit(&list);
 679
 680                                 if (current->generation > GENERATION_NUMBER_MAX)
 681                                         current->generation = GENERATION_NUMBER_MAX;
 682                         }
 683                 }
 684         }
 685 }
 686
 687 static int add_ref_to_list(const char *refname,
 688                            const struct object_id *oid,
 689                            int flags, void *cb_data)
 690 {
 691         struct string_list *list = (struct string_list *)cb_data;
 692
 693         string_list_append(list, oid_to_hex(oid));
 694         return 0;
 695 }
 696
 697 void write_commit_graph_reachable(const char *obj_dir, int append)
 698 {
 699         struct string_list list;
 700
 701         string_list_init(&list, 1);
 702         for_each_ref(add_ref_to_list, &list);
 703         write_commit_graph(obj_dir, NULL, &list, append);
 704 }
 705
 706 void write_commit_graph(const char *obj_dir,
 707                         struct string_list *pack_indexes,
 708                         struct string_list *commit_hex,
 709                         int append)
 710 {
 711         struct packed_oid_list oids;
 712         struct packed_commit_list commits;
 713         struct hashfile *f;
 714         uint32_t i, count_distinct = 0;
 715         char *graph_name;
 716         struct lock_file lk = LOCK_INIT;
 717         uint32_t chunk_ids[5];
 718         uint64_t chunk_offsets[5];
 719         int num_chunks;
 720         int num_extra_edges;
 721         struct commit_list *parent;
 722
 723         if (!commit_graph_compatible(the_repository))
 724                 return;
 725
 726         oids.nr = 0;
 727         oids.alloc = approximate_object_count() / 4;
 728
 729         if (append) {
 730                 prepare_commit_graph_one(the_repository, obj_dir);
 731                 if (the_repository->objects->commit_graph)
 732                         oids.alloc += the_repository->objects->commit_graph->num_commits;
 733         }
 734
 735         if (oids.alloc < 1024)
 736                 oids.alloc = 1024;
 737         ALLOC_ARRAY(oids.list, oids.alloc);
 738
 739         if (append && the_repository->objects->commit_graph) {
 740                 struct commit_graph *commit_graph =
 741                         the_repository->objects->commit_graph;
 742                 for (i = 0; i < commit_graph->num_commits; i++) {
 743                         const unsigned char *hash = commit_graph->chunk_oid_lookup +
 744                                 commit_graph->hash_len * i;
 745                         hashcpy(oids.list[oids.nr++].hash, hash);
 746                 }
 747         }
 748
 749         if (pack_indexes) {
 750                 struct strbuf packname = STRBUF_INIT;
 751                 int dirlen;
 752                 strbuf_addf(&packname, "%s/pack/", obj_dir);
 753                 dirlen = packname.len;
 754                 for (i = 0; i < pack_indexes->nr; i++) {
 755                         struct packed_git *p;
 756                         strbuf_setlen(&packname, dirlen);
 757                         strbuf_addstr(&packname, pack_indexes->items[i].string);
 758                         p = add_packed_git(packname.buf, packname.len, 1);
 759                         if (!p)
 760                                 die("error adding pack %s", packname.buf);
 761                         if (open_pack_index(p))
 762                                 die("error opening index for %s", packname.buf);
 763                         for_each_object_in_pack(p, add_packed_commits, &oids);
 764                         close_pack(p);
 765                 }
 766                 strbuf_release(&packname);
 767         }
 768
 769         if (commit_hex) {
 770                 for (i = 0; i < commit_hex->nr; i++) {
 771                         const char *end;
 772                         struct object_id oid;
 773                         struct commit *result;
 774
 775                         if (commit_hex->items[i].string &&
 776                             parse_oid_hex(commit_hex->items[i].string, &oid, &end))
 777                                 continue;
 778
 779                         result = lookup_commit_reference_gently(the_repository, &oid, 1);
 780
 781                         if (result) {
 782                                 ALLOC_GROW(oids.list, oids.nr + 1, oids.alloc);
 783                                 oidcpy(&oids.list[oids.nr], &(result->object.oid));
 784                                 oids.nr++;
 785                         }
 786                 }
 787         }
 788
 789         if (!pack_indexes && !commit_hex)
 790                 for_each_packed_object(add_packed_commits, &oids, 0);
 791
 792         close_reachable(&oids);
 793
 794         QSORT(oids.list, oids.nr, commit_compare);
 795
 796         count_distinct = 1;
 797         for (i = 1; i < oids.nr; i++) {
 798                 if (oidcmp(&oids.list[i-1], &oids.list[i]))
 799                         count_distinct++;
 800         }
 801
 802         if (count_distinct >= GRAPH_PARENT_MISSING)
 803                 die(_("the commit graph format cannot write %d commits"), count_distinct);
 804
 805         commits.nr = 0;
 806         commits.alloc = count_distinct;
 807         ALLOC_ARRAY(commits.list, commits.alloc);
 808
 809         num_extra_edges = 0;
 810         for (i = 0; i < oids.nr; i++) {
 811                 int num_parents = 0;
 812                 if (i > 0 && !oidcmp(&oids.list[i-1], &oids.list[i]))
 813                         continue;
 814
 815                 commits.list[commits.nr] = lookup_commit(the_repository, &oids.list[i]);
 816                 parse_commit(commits.list[commits.nr]);
 817
 818                 for (parent = commits.list[commits.nr]->parents;
 819                      parent; parent = parent->next)
 820                         num_parents++;
 821
 822                 if (num_parents > 2)
 823                         num_extra_edges += num_parents - 1;
 824
 825                 commits.nr++;
 826         }
 827         num_chunks = num_extra_edges ? 4 : 3;
 828
 829         if (commits.nr >= GRAPH_PARENT_MISSING)
 830                 die(_("too many commits to write graph"));
 831
 832         compute_generation_numbers(&commits);
 833
 834         graph_name = get_commit_graph_filename(obj_dir);
 835         if (safe_create_leading_directories(graph_name))
 836                 die_errno(_("unable to create leading directories of %s"),
 837                           graph_name);
 838
 839         hold_lock_file_for_update(&lk, graph_name, LOCK_DIE_ON_ERROR);
 840         f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
 841
 842         hashwrite_be32(f, GRAPH_SIGNATURE);
 843
 844         hashwrite_u8(f, GRAPH_VERSION);
 845         hashwrite_u8(f, GRAPH_OID_VERSION);
 846         hashwrite_u8(f, num_chunks);
 847         hashwrite_u8(f, 0); /* unused padding byte */
 848
 849         chunk_ids[0] = GRAPH_CHUNKID_OIDFANOUT;
 850         chunk_ids[1] = GRAPH_CHUNKID_OIDLOOKUP;
 851         chunk_ids[2] = GRAPH_CHUNKID_DATA;
 852         if (num_extra_edges)
 853                 chunk_ids[3] = GRAPH_CHUNKID_LARGEEDGES;
 854         else
 855                 chunk_ids[3] = 0;
 856         chunk_ids[4] = 0;
 857
 858         chunk_offsets[0] = 8 + (num_chunks + 1) * GRAPH_CHUNKLOOKUP_WIDTH;
 859         chunk_offsets[1] = chunk_offsets[0] + GRAPH_FANOUT_SIZE;
 860         chunk_offsets[2] = chunk_offsets[1] + GRAPH_OID_LEN * commits.nr;
 861         chunk_offsets[3] = chunk_offsets[2] + (GRAPH_OID_LEN + 16) * commits.nr;
 862         chunk_offsets[4] = chunk_offsets[3] + 4 * num_extra_edges;
 863
 864         for (i = 0; i <= num_chunks; i++) {
 865                 uint32_t chunk_write[3];
 866
 867                 chunk_write[0] = htonl(chunk_ids[i]);
 868                 chunk_write[1] = htonl(chunk_offsets[i] >> 32);
 869                 chunk_write[2] = htonl(chunk_offsets[i] & 0xffffffff);
 870                 hashwrite(f, chunk_write, 12);
 871         }
 872
 873         write_graph_chunk_fanout(f, commits.list, commits.nr);
 874         write_graph_chunk_oids(f, GRAPH_OID_LEN, commits.list, commits.nr);
 875         write_graph_chunk_data(f, GRAPH_OID_LEN, commits.list, commits.nr);
 876         write_graph_chunk_large_edges(f, commits.list, commits.nr);
 877
 878         close_commit_graph();
 879         finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_FSYNC);
 880         commit_lock_file(&lk);
 881
 882         free(oids.list);
 883         oids.alloc = 0;
 884         oids.nr = 0;
 885 }
 886
 887 #define VERIFY_COMMIT_GRAPH_ERROR_HASH 2
 888 static int verify_commit_graph_error;
 889
 890 static void graph_report(const char *fmt, ...)
 891 {
 892         va_list ap;
 893
 894         verify_commit_graph_error = 1;
 895         va_start(ap, fmt);
 896         vfprintf(stderr, fmt, ap);
 897         fprintf(stderr, "\n");
 898         va_end(ap);
 899 }
 900
 901 #define GENERATION_ZERO_EXISTS 1
 902 #define GENERATION_NUMBER_EXISTS 2
 903
 904 int verify_commit_graph(struct repository *r, struct commit_graph *g)
 905 {
 906         uint32_t i, cur_fanout_pos = 0;
 907         struct object_id prev_oid, cur_oid, checksum;
 908         int generation_zero = 0;
 909         struct hashfile *f;
 910         int devnull;
 911
 912         if (!g) {
 913                 graph_report("no commit-graph file loaded");
 914                 return 1;
 915         }
 916
 917         verify_commit_graph_error = 0;
 918
 919         if (!g->chunk_oid_fanout)
 920                 graph_report("commit-graph is missing the OID Fanout chunk");
 921         if (!g->chunk_oid_lookup)
 922                 graph_report("commit-graph is missing the OID Lookup chunk");
 923         if (!g->chunk_commit_data)
 924                 graph_report("commit-graph is missing the Commit Data chunk");
 925
 926         if (verify_commit_graph_error)
 927                 return verify_commit_graph_error;
 928
 929         devnull = open("/dev/null", O_WRONLY);
 930         f = hashfd(devnull, NULL);
 931         hashwrite(f, g->data, g->data_len - g->hash_len);
 932         finalize_hashfile(f, checksum.hash, CSUM_CLOSE);
 933         if (hashcmp(checksum.hash, g->data + g->data_len - g->hash_len)) {
 934                 graph_report(_("the commit-graph file has incorrect checksum and is likely corrupt"));
 935                 verify_commit_graph_error = VERIFY_COMMIT_GRAPH_ERROR_HASH;
 936         }
 937
 938         for (i = 0; i < g->num_commits; i++) {
 939                 struct commit *graph_commit;
 940
 941                 hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
 942
 943                 if (i && oidcmp(&prev_oid, &cur_oid) >= 0)
 944                         graph_report("commit-graph has incorrect OID order: %s then %s",
 945                                      oid_to_hex(&prev_oid),
 946                                      oid_to_hex(&cur_oid));
 947
 948                 oidcpy(&prev_oid, &cur_oid);
 949
 950                 while (cur_oid.hash[0] > cur_fanout_pos) {
 951                         uint32_t fanout_value = get_be32(g->chunk_oid_fanout + cur_fanout_pos);
 952
 953                         if (i != fanout_value)
 954                                 graph_report("commit-graph has incorrect fanout value: fanout[%d] = %u != %u",
 955                                              cur_fanout_pos, fanout_value, i);
 956                         cur_fanout_pos++;
 957                 }
 958
 959                 graph_commit = lookup_commit(r, &cur_oid);
 960                 if (!parse_commit_in_graph_one(g, graph_commit))
 961                         graph_report("failed to parse %s from commit-graph",
 962                                      oid_to_hex(&cur_oid));
 963         }
 964
 965         while (cur_fanout_pos < 256) {
 966                 uint32_t fanout_value = get_be32(g->chunk_oid_fanout + cur_fanout_pos);
 967
 968                 if (g->num_commits != fanout_value)
 969                         graph_report("commit-graph has incorrect fanout value: fanout[%d] = %u != %u",
 970                                      cur_fanout_pos, fanout_value, i);
 971
 972                 cur_fanout_pos++;
 973         }
 974
 975         if (verify_commit_graph_error & ~VERIFY_COMMIT_GRAPH_ERROR_HASH)
 976                 return verify_commit_graph_error;
 977
 978         for (i = 0; i < g->num_commits; i++) {
 979                 struct commit *graph_commit, *odb_commit;
 980                 struct commit_list *graph_parents, *odb_parents;
 981                 uint32_t max_generation = 0;
 982
 983                 hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
 984
 985                 graph_commit = lookup_commit(r, &cur_oid);
 986                 odb_commit = (struct commit *)create_object(r, cur_oid.hash, alloc_commit_node(r));
 987                 if (parse_commit_internal(odb_commit, 0, 0)) {
 988                         graph_report("failed to parse %s from object database",
 989                                      oid_to_hex(&cur_oid));
 990                         continue;
 991                 }
 992
 993                 if (oidcmp(&get_commit_tree_in_graph_one(g, graph_commit)->object.oid,
 994                            get_commit_tree_oid(odb_commit)))
 995                         graph_report("root tree OID for commit %s in commit-graph is %s != %s",
 996                                      oid_to_hex(&cur_oid),
 997                                      oid_to_hex(get_commit_tree_oid(graph_commit)),
 998                                      oid_to_hex(get_commit_tree_oid(odb_commit)));
 999
1000                 graph_parents = graph_commit->parents;
1001                 odb_parents = odb_commit->parents;
1002
1003                 while (graph_parents) {
1004                         if (odb_parents == NULL) {
1005                                 graph_report("commit-graph parent list for commit %s is too long",
1006                                              oid_to_hex(&cur_oid));
1007                                 break;
1008                         }
1009
1010                         if (oidcmp(&graph_parents->item->object.oid, &odb_parents->item->object.oid))
1011                                 graph_report("commit-graph parent for %s is %s != %s",
1012                                              oid_to_hex(&cur_oid),
1013                                              oid_to_hex(&graph_parents->item->object.oid),
1014                                              oid_to_hex(&odb_parents->item->object.oid));
1015
1016                         if (graph_parents->item->generation > max_generation)
1017                                 max_generation = graph_parents->item->generation;
1018
1019                         graph_parents = graph_parents->next;
1020                         odb_parents = odb_parents->next;
1021                 }
1022
1023                 if (odb_parents != NULL)
1024                         graph_report("commit-graph parent list for commit %s terminates early",
1025                                      oid_to_hex(&cur_oid));
1026
1027                 if (!graph_commit->generation) {
1028                         if (generation_zero == GENERATION_NUMBER_EXISTS)
1029                                 graph_report("commit-graph has generation number zero for commit %s, but non-zero elsewhere",
1030                                              oid_to_hex(&cur_oid));
1031                         generation_zero = GENERATION_ZERO_EXISTS;
1032                 } else if (generation_zero == GENERATION_ZERO_EXISTS)
1033                         graph_report("commit-graph has non-zero generation number for commit %s, but zero elsewhere",
1034                                      oid_to_hex(&cur_oid));
1035
1036                 if (generation_zero == GENERATION_ZERO_EXISTS)
1037                         continue;
1038
1039                 /*
1040                  * If one of our parents has generation GENERATION_NUMBER_MAX, then
1041                  * our generation is also GENERATION_NUMBER_MAX. Decrement to avoid
1042                  * extra logic in the following condition.
1043                  */
1044                 if (max_generation == GENERATION_NUMBER_MAX)
1045                         max_generation--;
1046
1047                 if (graph_commit->generation != max_generation + 1)
1048                         graph_report("commit-graph generation for commit %s is %u != %u",
1049                                      oid_to_hex(&cur_oid),
1050                                      graph_commit->generation,
1051                                      max_generation + 1);
1052
1053                 if (graph_commit->date != odb_commit->date)
1054                         graph_report("commit date for commit %s in commit-graph is %"PRItime" != %"PRItime,
1055                                      oid_to_hex(&cur_oid),
1056                                      graph_commit->date,
1057                                      odb_commit->date);
1058         }
1059
1060         return verify_commit_graph_error;
1061 }
1062
1063 void free_commit_graph(struct commit_graph *g)
1064 {
1065         if (!g)
1066                 return;
1067         if (g->graph_fd >= 0) {
1068                 munmap((void *)g->data, g->data_len);
1069                 g->data = NULL;
1070                 close(g->graph_fd);
1071         }
1072         free(g);
1073 }