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 #include "progress.h"
  19
  20 #define GRAPH_SIGNATURE 0x43475048 /* "CGPH" */
  21 #define GRAPH_CHUNKID_OIDFANOUT 0x4f494446 /* "OIDF" */
  22 #define GRAPH_CHUNKID_OIDLOOKUP 0x4f49444c /* "OIDL" */
  23 #define GRAPH_CHUNKID_DATA 0x43444154 /* "CDAT" */
  24 #define GRAPH_CHUNKID_LARGEEDGES 0x45444745 /* "EDGE" */
  25
  26 #define GRAPH_DATA_WIDTH 36
  27
  28 #define GRAPH_VERSION_1 0x1
  29 #define GRAPH_VERSION GRAPH_VERSION_1
  30
  31 #define GRAPH_OID_VERSION_SHA1 1
  32 #define GRAPH_OID_LEN_SHA1 GIT_SHA1_RAWSZ
  33 #define GRAPH_OID_VERSION GRAPH_OID_VERSION_SHA1
  34 #define GRAPH_OID_LEN GRAPH_OID_LEN_SHA1
  35
  36 #define GRAPH_OCTOPUS_EDGES_NEEDED 0x80000000
  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 (!git_env_bool(GIT_TEST_COMMIT_GRAPH, 0) &&
 241             (repo_config_get_bool(r, "core.commitgraph", &config_value) ||
 242             !config_value))
 243                 /*
 244                  * This repository is not configured to use commit graphs, so
 245                  * do not load one. (But report commit_graph_attempted anyway
 246                  * so that commit graph loading is not attempted again for this
 247                  * repository.)
 248                  */
 249                 return 0;
 250
 251         if (!commit_graph_compatible(r))
 252                 return 0;
 253
 254         obj_dir = r->objects->objectdir;
 255         prepare_commit_graph_one(r, obj_dir);
 256         prepare_alt_odb(r);
 257         for (alt = r->objects->alt_odb_list;
 258              !r->objects->commit_graph && alt;
 259              alt = alt->next)
 260                 prepare_commit_graph_one(r, alt->path);
 261         return !!r->objects->commit_graph;
 262 }
 263
 264 int generation_numbers_enabled(struct repository *r)
 265 {
 266         uint32_t first_generation;
 267         struct commit_graph *g;
 268         if (!prepare_commit_graph(r))
 269                return 0;
 270
 271         g = r->objects->commit_graph;
 272
 273         if (!g->num_commits)
 274                 return 0;
 275
 276         first_generation = get_be32(g->chunk_commit_data +
 277                                     g->hash_len + 8) >> 2;
 278
 279         return !!first_generation;
 280 }
 281
 282 void close_commit_graph(struct repository *r)
 283 {
 284         free_commit_graph(r->objects->commit_graph);
 285         r->objects->commit_graph = NULL;
 286 }
 287
 288 static int bsearch_graph(struct commit_graph *g, struct object_id *oid, uint32_t *pos)
 289 {
 290         return bsearch_hash(oid->hash, g->chunk_oid_fanout,
 291                             g->chunk_oid_lookup, g->hash_len, pos);
 292 }
 293
 294 static struct commit_list **insert_parent_or_die(struct commit_graph *g,
 295                                                  uint64_t pos,
 296                                                  struct commit_list **pptr)
 297 {
 298         struct commit *c;
 299         struct object_id oid;
 300
 301         if (pos >= g->num_commits)
 302                 die("invalid parent position %"PRIu64, pos);
 303
 304         hashcpy(oid.hash, g->chunk_oid_lookup + g->hash_len * pos);
 305         c = lookup_commit(the_repository, &oid);
 306         if (!c)
 307                 die(_("could not find commit %s"), oid_to_hex(&oid));
 308         c->graph_pos = pos;
 309         return &commit_list_insert(c, pptr)->next;
 310 }
 311
 312 static void fill_commit_graph_info(struct commit *item, struct commit_graph *g, uint32_t pos)
 313 {
 314         const unsigned char *commit_data = g->chunk_commit_data + GRAPH_DATA_WIDTH * pos;
 315         item->graph_pos = pos;
 316         item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
 317 }
 318
 319 static int fill_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t pos)
 320 {
 321         uint32_t edge_value;
 322         uint32_t *parent_data_ptr;
 323         uint64_t date_low, date_high;
 324         struct commit_list **pptr;
 325         const unsigned char *commit_data = g->chunk_commit_data + (g->hash_len + 16) * pos;
 326
 327         item->object.parsed = 1;
 328         item->graph_pos = pos;
 329
 330         item->maybe_tree = NULL;
 331
 332         date_high = get_be32(commit_data + g->hash_len + 8) & 0x3;
 333         date_low = get_be32(commit_data + g->hash_len + 12);
 334         item->date = (timestamp_t)((date_high << 32) | date_low);
 335
 336         item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
 337
 338         pptr = &item->parents;
 339
 340         edge_value = get_be32(commit_data + g->hash_len);
 341         if (edge_value == GRAPH_PARENT_NONE)
 342                 return 1;
 343         pptr = insert_parent_or_die(g, edge_value, pptr);
 344
 345         edge_value = get_be32(commit_data + g->hash_len + 4);
 346         if (edge_value == GRAPH_PARENT_NONE)
 347                 return 1;
 348         if (!(edge_value & GRAPH_OCTOPUS_EDGES_NEEDED)) {
 349                 pptr = insert_parent_or_die(g, edge_value, pptr);
 350                 return 1;
 351         }
 352
 353         parent_data_ptr = (uint32_t*)(g->chunk_large_edges +
 354                           4 * (uint64_t)(edge_value & GRAPH_EDGE_LAST_MASK));
 355         do {
 356                 edge_value = get_be32(parent_data_ptr);
 357                 pptr = insert_parent_or_die(g,
 358                                             edge_value & GRAPH_EDGE_LAST_MASK,
 359                                             pptr);
 360                 parent_data_ptr++;
 361         } while (!(edge_value & GRAPH_LAST_EDGE));
 362
 363         return 1;
 364 }
 365
 366 static int find_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t *pos)
 367 {
 368         if (item->graph_pos != COMMIT_NOT_FROM_GRAPH) {
 369                 *pos = item->graph_pos;
 370                 return 1;
 371         } else {
 372                 return bsearch_graph(g, &(item->object.oid), pos);
 373         }
 374 }
 375
 376 static int parse_commit_in_graph_one(struct commit_graph *g, struct commit *item)
 377 {
 378         uint32_t pos;
 379
 380         if (item->object.parsed)
 381                 return 1;
 382
 383         if (find_commit_in_graph(item, g, &pos))
 384                 return fill_commit_in_graph(item, g, pos);
 385
 386         return 0;
 387 }
 388
 389 int parse_commit_in_graph(struct repository *r, struct commit *item)
 390 {
 391         if (!prepare_commit_graph(r))
 392                 return 0;
 393         return parse_commit_in_graph_one(r->objects->commit_graph, item);
 394 }
 395
 396 void load_commit_graph_info(struct repository *r, struct commit *item)
 397 {
 398         uint32_t pos;
 399         if (!prepare_commit_graph(r))
 400                 return;
 401         if (find_commit_in_graph(item, r->objects->commit_graph, &pos))
 402                 fill_commit_graph_info(item, r->objects->commit_graph, pos);
 403 }
 404
 405 static struct tree *load_tree_for_commit(struct commit_graph *g, struct commit *c)
 406 {
 407         struct object_id oid;
 408         const unsigned char *commit_data = g->chunk_commit_data +
 409                                            GRAPH_DATA_WIDTH * (c->graph_pos);
 410
 411         hashcpy(oid.hash, commit_data);
 412         c->maybe_tree = lookup_tree(the_repository, &oid);
 413
 414         return c->maybe_tree;
 415 }
 416
 417 static struct tree *get_commit_tree_in_graph_one(struct commit_graph *g,
 418                                                  const struct commit *c)
 419 {
 420         if (c->maybe_tree)
 421                 return c->maybe_tree;
 422         if (c->graph_pos == COMMIT_NOT_FROM_GRAPH)
 423                 BUG("get_commit_tree_in_graph_one called from non-commit-graph commit");
 424
 425         return load_tree_for_commit(g, (struct commit *)c);
 426 }
 427
 428 struct tree *get_commit_tree_in_graph(struct repository *r, const struct commit *c)
 429 {
 430         return get_commit_tree_in_graph_one(r->objects->commit_graph, c);
 431 }
 432
 433 static void write_graph_chunk_fanout(struct hashfile *f,
 434                                      struct commit **commits,
 435                                      int nr_commits)
 436 {
 437         int i, count = 0;
 438         struct commit **list = commits;
 439
 440         /*
 441          * Write the first-level table (the list is sorted,
 442          * but we use a 256-entry lookup to be able to avoid
 443          * having to do eight extra binary search iterations).
 444          */
 445         for (i = 0; i < 256; i++) {
 446                 while (count < nr_commits) {
 447                         if ((*list)->object.oid.hash[0] != i)
 448                                 break;
 449                         count++;
 450                         list++;
 451                 }
 452
 453                 hashwrite_be32(f, count);
 454         }
 455 }
 456
 457 static void write_graph_chunk_oids(struct hashfile *f, int hash_len,
 458                                    struct commit **commits, int nr_commits)
 459 {
 460         struct commit **list = commits;
 461         int count;
 462         for (count = 0; count < nr_commits; count++, list++)
 463                 hashwrite(f, (*list)->object.oid.hash, (int)hash_len);
 464 }
 465
 466 static const unsigned char *commit_to_sha1(size_t index, void *table)
 467 {
 468         struct commit **commits = table;
 469         return commits[index]->object.oid.hash;
 470 }
 471
 472 static void write_graph_chunk_data(struct hashfile *f, int hash_len,
 473                                    struct commit **commits, int nr_commits)
 474 {
 475         struct commit **list = commits;
 476         struct commit **last = commits + nr_commits;
 477         uint32_t num_extra_edges = 0;
 478
 479         while (list < last) {
 480                 struct commit_list *parent;
 481                 int edge_value;
 482                 uint32_t packedDate[2];
 483
 484                 parse_commit(*list);
 485                 hashwrite(f, get_commit_tree_oid(*list)->hash, hash_len);
 486
 487                 parent = (*list)->parents;
 488
 489                 if (!parent)
 490                         edge_value = GRAPH_PARENT_NONE;
 491                 else {
 492                         edge_value = sha1_pos(parent->item->object.oid.hash,
 493                                               commits,
 494                                               nr_commits,
 495                                               commit_to_sha1);
 496
 497                         if (edge_value < 0)
 498                                 BUG("missing parent %s for commit %s",
 499                                     oid_to_hex(&parent->item->object.oid),
 500                                     oid_to_hex(&(*list)->object.oid));
 501                 }
 502
 503                 hashwrite_be32(f, edge_value);
 504
 505                 if (parent)
 506                         parent = parent->next;
 507
 508                 if (!parent)
 509                         edge_value = GRAPH_PARENT_NONE;
 510                 else if (parent->next)
 511                         edge_value = GRAPH_OCTOPUS_EDGES_NEEDED | num_extra_edges;
 512                 else {
 513                         edge_value = sha1_pos(parent->item->object.oid.hash,
 514                                               commits,
 515                                               nr_commits,
 516                                               commit_to_sha1);
 517                         if (edge_value < 0)
 518                                 BUG("missing parent %s for commit %s",
 519                                     oid_to_hex(&parent->item->object.oid),
 520                                     oid_to_hex(&(*list)->object.oid));
 521                 }
 522
 523                 hashwrite_be32(f, edge_value);
 524
 525                 if (edge_value & GRAPH_OCTOPUS_EDGES_NEEDED) {
 526                         do {
 527                                 num_extra_edges++;
 528                                 parent = parent->next;
 529                         } while (parent);
 530                 }
 531
 532                 if (sizeof((*list)->date) > 4)
 533                         packedDate[0] = htonl(((*list)->date >> 32) & 0x3);
 534                 else
 535                         packedDate[0] = 0;
 536
 537                 packedDate[0] |= htonl((*list)->generation << 2);
 538
 539                 packedDate[1] = htonl((*list)->date);
 540                 hashwrite(f, packedDate, 8);
 541
 542                 list++;
 543         }
 544 }
 545
 546 static void write_graph_chunk_large_edges(struct hashfile *f,
 547                                           struct commit **commits,
 548                                           int nr_commits)
 549 {
 550         struct commit **list = commits;
 551         struct commit **last = commits + nr_commits;
 552         struct commit_list *parent;
 553
 554         while (list < last) {
 555                 int num_parents = 0;
 556                 for (parent = (*list)->parents; num_parents < 3 && parent;
 557                      parent = parent->next)
 558                         num_parents++;
 559
 560                 if (num_parents <= 2) {
 561                         list++;
 562                         continue;
 563                 }
 564
 565                 /* Since num_parents > 2, this initializer is safe. */
 566                 for (parent = (*list)->parents->next; parent; parent = parent->next) {
 567                         int edge_value = sha1_pos(parent->item->object.oid.hash,
 568                                                   commits,
 569                                                   nr_commits,
 570                                                   commit_to_sha1);
 571
 572                         if (edge_value < 0)
 573                                 BUG("missing parent %s for commit %s",
 574                                     oid_to_hex(&parent->item->object.oid),
 575                                     oid_to_hex(&(*list)->object.oid));
 576                         else if (!parent->next)
 577                                 edge_value |= GRAPH_LAST_EDGE;
 578
 579                         hashwrite_be32(f, edge_value);
 580                 }
 581
 582                 list++;
 583         }
 584 }
 585
 586 static int commit_compare(const void *_a, const void *_b)
 587 {
 588         const struct object_id *a = (const struct object_id *)_a;
 589         const struct object_id *b = (const struct object_id *)_b;
 590         return oidcmp(a, b);
 591 }
 592
 593 struct packed_commit_list {
 594         struct commit **list;
 595         int nr;
 596         int alloc;
 597 };
 598
 599 struct packed_oid_list {
 600         struct object_id *list;
 601         int nr;
 602         int alloc;
 603         struct progress *progress;
 604         int progress_done;
 605 };
 606
 607 static int add_packed_commits(const struct object_id *oid,
 608                               struct packed_git *pack,
 609                               uint32_t pos,
 610                               void *data)
 611 {
 612         struct packed_oid_list *list = (struct packed_oid_list*)data;
 613         enum object_type type;
 614         off_t offset = nth_packed_object_offset(pack, pos);
 615         struct object_info oi = OBJECT_INFO_INIT;
 616
 617         if (list->progress)
 618                 display_progress(list->progress, ++list->progress_done);
 619
 620         oi.typep = &type;
 621         if (packed_object_info(the_repository, pack, offset, &oi) < 0)
 622                 die(_("unable to get type of object %s"), oid_to_hex(oid));
 623
 624         if (type != OBJ_COMMIT)
 625                 return 0;
 626
 627         ALLOC_GROW(list->list, list->nr + 1, list->alloc);
 628         oidcpy(&(list->list[list->nr]), oid);
 629         list->nr++;
 630
 631         return 0;
 632 }
 633
 634 static void add_missing_parents(struct packed_oid_list *oids, struct commit *commit)
 635 {
 636         struct commit_list *parent;
 637         for (parent = commit->parents; parent; parent = parent->next) {
 638                 if (!(parent->item->object.flags & UNINTERESTING)) {
 639                         ALLOC_GROW(oids->list, oids->nr + 1, oids->alloc);
 640                         oidcpy(&oids->list[oids->nr], &(parent->item->object.oid));
 641                         oids->nr++;
 642                         parent->item->object.flags |= UNINTERESTING;
 643                 }
 644         }
 645 }
 646
 647 static void close_reachable(struct packed_oid_list *oids, int report_progress)
 648 {
 649         int i;
 650         struct commit *commit;
 651         struct progress *progress = NULL;
 652         int j = 0;
 653
 654         if (report_progress)
 655                 progress = start_delayed_progress(
 656                         _("Annotating commits in commit graph"), 0);
 657         for (i = 0; i < oids->nr; i++) {
 658                 display_progress(progress, ++j);
 659                 commit = lookup_commit(the_repository, &oids->list[i]);
 660                 if (commit)
 661                         commit->object.flags |= UNINTERESTING;
 662         }
 663
 664         /*
 665          * As this loop runs, oids->nr may grow, but not more
 666          * than the number of missing commits in the reachable
 667          * closure.
 668          */
 669         for (i = 0; i < oids->nr; i++) {
 670                 display_progress(progress, ++j);
 671                 commit = lookup_commit(the_repository, &oids->list[i]);
 672
 673                 if (commit && !parse_commit(commit))
 674                         add_missing_parents(oids, commit);
 675         }
 676
 677         for (i = 0; i < oids->nr; i++) {
 678                 display_progress(progress, ++j);
 679                 commit = lookup_commit(the_repository, &oids->list[i]);
 680
 681                 if (commit)
 682                         commit->object.flags &= ~UNINTERESTING;
 683         }
 684         stop_progress(&progress);
 685 }
 686
 687 static void compute_generation_numbers(struct packed_commit_list* commits,
 688                                        int report_progress)
 689 {
 690         int i;
 691         struct commit_list *list = NULL;
 692         struct progress *progress = NULL;
 693
 694         if (report_progress)
 695                 progress = start_progress(
 696                         _("Computing commit graph generation numbers"),
 697                         commits->nr);
 698         for (i = 0; i < commits->nr; i++) {
 699                 display_progress(progress, i + 1);
 700                 if (commits->list[i]->generation != GENERATION_NUMBER_INFINITY &&
 701                     commits->list[i]->generation != GENERATION_NUMBER_ZERO)
 702                         continue;
 703
 704                 commit_list_insert(commits->list[i], &list);
 705                 while (list) {
 706                         struct commit *current = list->item;
 707                         struct commit_list *parent;
 708                         int all_parents_computed = 1;
 709                         uint32_t max_generation = 0;
 710
 711                         for (parent = current->parents; parent; parent = parent->next) {
 712                                 if (parent->item->generation == GENERATION_NUMBER_INFINITY ||
 713                                     parent->item->generation == GENERATION_NUMBER_ZERO) {
 714                                         all_parents_computed = 0;
 715                                         commit_list_insert(parent->item, &list);
 716                                         break;
 717                                 } else if (parent->item->generation > max_generation) {
 718                                         max_generation = parent->item->generation;
 719                                 }
 720                         }
 721
 722                         if (all_parents_computed) {
 723                                 current->generation = max_generation + 1;
 724                                 pop_commit(&list);
 725
 726                                 if (current->generation > GENERATION_NUMBER_MAX)
 727                                         current->generation = GENERATION_NUMBER_MAX;
 728                         }
 729                 }
 730         }
 731         stop_progress(&progress);
 732 }
 733
 734 static int add_ref_to_list(const char *refname,
 735                            const struct object_id *oid,
 736                            int flags, void *cb_data)
 737 {
 738         struct string_list *list = (struct string_list *)cb_data;
 739
 740         string_list_append(list, oid_to_hex(oid));
 741         return 0;
 742 }
 743
 744 void write_commit_graph_reachable(const char *obj_dir, int append,
 745                                   int report_progress)
 746 {
 747         struct string_list list = STRING_LIST_INIT_DUP;
 748
 749         for_each_ref(add_ref_to_list, &list);
 750         write_commit_graph(obj_dir, NULL, &list, append, report_progress);
 751
 752         string_list_clear(&list, 0);
 753 }
 754
 755 void write_commit_graph(const char *obj_dir,
 756                         struct string_list *pack_indexes,
 757                         struct string_list *commit_hex,
 758                         int append, int report_progress)
 759 {
 760         struct packed_oid_list oids;
 761         struct packed_commit_list commits;
 762         struct hashfile *f;
 763         uint32_t i, count_distinct = 0;
 764         char *graph_name;
 765         struct lock_file lk = LOCK_INIT;
 766         uint32_t chunk_ids[5];
 767         uint64_t chunk_offsets[5];
 768         int num_chunks;
 769         int num_extra_edges;
 770         struct commit_list *parent;
 771         struct progress *progress = NULL;
 772
 773         if (!commit_graph_compatible(the_repository))
 774                 return;
 775
 776         oids.nr = 0;
 777         oids.alloc = approximate_object_count() / 32;
 778         oids.progress = NULL;
 779         oids.progress_done = 0;
 780
 781         if (append) {
 782                 prepare_commit_graph_one(the_repository, obj_dir);
 783                 if (the_repository->objects->commit_graph)
 784                         oids.alloc += the_repository->objects->commit_graph->num_commits;
 785         }
 786
 787         if (oids.alloc < 1024)
 788                 oids.alloc = 1024;
 789         ALLOC_ARRAY(oids.list, oids.alloc);
 790
 791         if (append && the_repository->objects->commit_graph) {
 792                 struct commit_graph *commit_graph =
 793                         the_repository->objects->commit_graph;
 794                 for (i = 0; i < commit_graph->num_commits; i++) {
 795                         const unsigned char *hash = commit_graph->chunk_oid_lookup +
 796                                 commit_graph->hash_len * i;
 797                         hashcpy(oids.list[oids.nr++].hash, hash);
 798                 }
 799         }
 800
 801         if (pack_indexes) {
 802                 struct strbuf packname = STRBUF_INIT;
 803                 int dirlen;
 804                 strbuf_addf(&packname, "%s/pack/", obj_dir);
 805                 dirlen = packname.len;
 806                 if (report_progress) {
 807                         oids.progress = start_delayed_progress(
 808                                 _("Finding commits for commit graph"), 0);
 809                         oids.progress_done = 0;
 810                 }
 811                 for (i = 0; i < pack_indexes->nr; i++) {
 812                         struct packed_git *p;
 813                         strbuf_setlen(&packname, dirlen);
 814                         strbuf_addstr(&packname, pack_indexes->items[i].string);
 815                         p = add_packed_git(packname.buf, packname.len, 1);
 816                         if (!p)
 817                                 die(_("error adding pack %s"), packname.buf);
 818                         if (open_pack_index(p))
 819                                 die(_("error opening index for %s"), packname.buf);
 820                         for_each_object_in_pack(p, add_packed_commits, &oids, 0);
 821                         close_pack(p);
 822                         free(p);
 823                 }
 824                 stop_progress(&oids.progress);
 825                 strbuf_release(&packname);
 826         }
 827
 828         if (commit_hex) {
 829                 if (report_progress)
 830                         progress = start_delayed_progress(
 831                                 _("Finding commits for commit graph"),
 832                                 commit_hex->nr);
 833                 for (i = 0; i < commit_hex->nr; i++) {
 834                         const char *end;
 835                         struct object_id oid;
 836                         struct commit *result;
 837
 838                         display_progress(progress, i + 1);
 839                         if (commit_hex->items[i].string &&
 840                             parse_oid_hex(commit_hex->items[i].string, &oid, &end))
 841                                 continue;
 842
 843                         result = lookup_commit_reference_gently(the_repository, &oid, 1);
 844
 845                         if (result) {
 846                                 ALLOC_GROW(oids.list, oids.nr + 1, oids.alloc);
 847                                 oidcpy(&oids.list[oids.nr], &(result->object.oid));
 848                                 oids.nr++;
 849                         }
 850                 }
 851                 stop_progress(&progress);
 852         }
 853
 854         if (!pack_indexes && !commit_hex) {
 855                 if (report_progress)
 856                         oids.progress = start_delayed_progress(
 857                                 _("Finding commits for commit graph"), 0);
 858                 for_each_packed_object(add_packed_commits, &oids, 0);
 859                 stop_progress(&oids.progress);
 860         }
 861
 862         close_reachable(&oids, report_progress);
 863
 864         QSORT(oids.list, oids.nr, commit_compare);
 865
 866         count_distinct = 1;
 867         for (i = 1; i < oids.nr; i++) {
 868                 if (!oideq(&oids.list[i - 1], &oids.list[i]))
 869                         count_distinct++;
 870         }
 871
 872         if (count_distinct >= GRAPH_EDGE_LAST_MASK)
 873                 die(_("the commit graph format cannot write %d commits"), count_distinct);
 874
 875         commits.nr = 0;
 876         commits.alloc = count_distinct;
 877         ALLOC_ARRAY(commits.list, commits.alloc);
 878
 879         num_extra_edges = 0;
 880         for (i = 0; i < oids.nr; i++) {
 881                 int num_parents = 0;
 882                 if (i > 0 && oideq(&oids.list[i - 1], &oids.list[i]))
 883                         continue;
 884
 885                 commits.list[commits.nr] = lookup_commit(the_repository, &oids.list[i]);
 886                 parse_commit(commits.list[commits.nr]);
 887
 888                 for (parent = commits.list[commits.nr]->parents;
 889                      parent; parent = parent->next)
 890                         num_parents++;
 891
 892                 if (num_parents > 2)
 893                         num_extra_edges += num_parents - 1;
 894
 895                 commits.nr++;
 896         }
 897         num_chunks = num_extra_edges ? 4 : 3;
 898
 899         if (commits.nr >= GRAPH_EDGE_LAST_MASK)
 900                 die(_("too many commits to write graph"));
 901
 902         compute_generation_numbers(&commits, report_progress);
 903
 904         graph_name = get_commit_graph_filename(obj_dir);
 905         if (safe_create_leading_directories(graph_name)) {
 906                 UNLEAK(graph_name);
 907                 die_errno(_("unable to create leading directories of %s"),
 908                           graph_name);
 909         }
 910
 911         hold_lock_file_for_update(&lk, graph_name, LOCK_DIE_ON_ERROR);
 912         f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
 913
 914         hashwrite_be32(f, GRAPH_SIGNATURE);
 915
 916         hashwrite_u8(f, GRAPH_VERSION);
 917         hashwrite_u8(f, GRAPH_OID_VERSION);
 918         hashwrite_u8(f, num_chunks);
 919         hashwrite_u8(f, 0); /* unused padding byte */
 920
 921         chunk_ids[0] = GRAPH_CHUNKID_OIDFANOUT;
 922         chunk_ids[1] = GRAPH_CHUNKID_OIDLOOKUP;
 923         chunk_ids[2] = GRAPH_CHUNKID_DATA;
 924         if (num_extra_edges)
 925                 chunk_ids[3] = GRAPH_CHUNKID_LARGEEDGES;
 926         else
 927                 chunk_ids[3] = 0;
 928         chunk_ids[4] = 0;
 929
 930         chunk_offsets[0] = 8 + (num_chunks + 1) * GRAPH_CHUNKLOOKUP_WIDTH;
 931         chunk_offsets[1] = chunk_offsets[0] + GRAPH_FANOUT_SIZE;
 932         chunk_offsets[2] = chunk_offsets[1] + GRAPH_OID_LEN * commits.nr;
 933         chunk_offsets[3] = chunk_offsets[2] + (GRAPH_OID_LEN + 16) * commits.nr;
 934         chunk_offsets[4] = chunk_offsets[3] + 4 * num_extra_edges;
 935
 936         for (i = 0; i <= num_chunks; i++) {
 937                 uint32_t chunk_write[3];
 938
 939                 chunk_write[0] = htonl(chunk_ids[i]);
 940                 chunk_write[1] = htonl(chunk_offsets[i] >> 32);
 941                 chunk_write[2] = htonl(chunk_offsets[i] & 0xffffffff);
 942                 hashwrite(f, chunk_write, 12);
 943         }
 944
 945         write_graph_chunk_fanout(f, commits.list, commits.nr);
 946         write_graph_chunk_oids(f, GRAPH_OID_LEN, commits.list, commits.nr);
 947         write_graph_chunk_data(f, GRAPH_OID_LEN, commits.list, commits.nr);
 948         write_graph_chunk_large_edges(f, commits.list, commits.nr);
 949
 950         close_commit_graph(the_repository);
 951         finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_FSYNC);
 952         commit_lock_file(&lk);
 953
 954         free(graph_name);
 955         free(commits.list);
 956         free(oids.list);
 957 }
 958
 959 #define VERIFY_COMMIT_GRAPH_ERROR_HASH 2
 960 static int verify_commit_graph_error;
 961
 962 static void graph_report(const char *fmt, ...)
 963 {
 964         va_list ap;
 965
 966         verify_commit_graph_error = 1;
 967         va_start(ap, fmt);
 968         vfprintf(stderr, fmt, ap);
 969         fprintf(stderr, "\n");
 970         va_end(ap);
 971 }
 972
 973 #define GENERATION_ZERO_EXISTS 1
 974 #define GENERATION_NUMBER_EXISTS 2
 975
 976 int verify_commit_graph(struct repository *r, struct commit_graph *g)
 977 {
 978         uint32_t i, cur_fanout_pos = 0;
 979         struct object_id prev_oid, cur_oid, checksum;
 980         int generation_zero = 0;
 981         struct hashfile *f;
 982         int devnull;
 983         struct progress *progress = NULL;
 984
 985         if (!g) {
 986                 graph_report("no commit-graph file loaded");
 987                 return 1;
 988         }
 989
 990         verify_commit_graph_error = 0;
 991
 992         if (!g->chunk_oid_fanout)
 993                 graph_report("commit-graph is missing the OID Fanout chunk");
 994         if (!g->chunk_oid_lookup)
 995                 graph_report("commit-graph is missing the OID Lookup chunk");
 996         if (!g->chunk_commit_data)
 997                 graph_report("commit-graph is missing the Commit Data chunk");
 998
 999         if (verify_commit_graph_error)
1000                 return verify_commit_graph_error;
1001
1002         devnull = open("/dev/null", O_WRONLY);
1003         f = hashfd(devnull, NULL);
1004         hashwrite(f, g->data, g->data_len - g->hash_len);
1005         finalize_hashfile(f, checksum.hash, CSUM_CLOSE);
1006         if (!hasheq(checksum.hash, g->data + g->data_len - g->hash_len)) {
1007                 graph_report(_("the commit-graph file has incorrect checksum and is likely corrupt"));
1008                 verify_commit_graph_error = VERIFY_COMMIT_GRAPH_ERROR_HASH;
1009         }
1010
1011         for (i = 0; i < g->num_commits; i++) {
1012                 struct commit *graph_commit;
1013
1014                 hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
1015
1016                 if (i && oidcmp(&prev_oid, &cur_oid) >= 0)
1017                         graph_report("commit-graph has incorrect OID order: %s then %s",
1018                                      oid_to_hex(&prev_oid),
1019                                      oid_to_hex(&cur_oid));
1020
1021                 oidcpy(&prev_oid, &cur_oid);
1022
1023                 while (cur_oid.hash[0] > cur_fanout_pos) {
1024                         uint32_t fanout_value = get_be32(g->chunk_oid_fanout + cur_fanout_pos);
1025
1026                         if (i != fanout_value)
1027                                 graph_report("commit-graph has incorrect fanout value: fanout[%d] = %u != %u",
1028                                              cur_fanout_pos, fanout_value, i);
1029                         cur_fanout_pos++;
1030                 }
1031
1032                 graph_commit = lookup_commit(r, &cur_oid);
1033                 if (!parse_commit_in_graph_one(g, graph_commit))
1034                         graph_report("failed to parse %s from commit-graph",
1035                                      oid_to_hex(&cur_oid));
1036         }
1037
1038         while (cur_fanout_pos < 256) {
1039                 uint32_t fanout_value = get_be32(g->chunk_oid_fanout + cur_fanout_pos);
1040
1041                 if (g->num_commits != fanout_value)
1042                         graph_report("commit-graph has incorrect fanout value: fanout[%d] = %u != %u",
1043                                      cur_fanout_pos, fanout_value, i);
1044
1045                 cur_fanout_pos++;
1046         }
1047
1048         if (verify_commit_graph_error & ~VERIFY_COMMIT_GRAPH_ERROR_HASH)
1049                 return verify_commit_graph_error;
1050
1051         progress = start_progress(_("Verifying commits in commit graph"),
1052                                   g->num_commits);
1053         for (i = 0; i < g->num_commits; i++) {
1054                 struct commit *graph_commit, *odb_commit;
1055                 struct commit_list *graph_parents, *odb_parents;
1056                 uint32_t max_generation = 0;
1057
1058                 display_progress(progress, i + 1);
1059                 hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
1060
1061                 graph_commit = lookup_commit(r, &cur_oid);
1062                 odb_commit = (struct commit *)create_object(r, cur_oid.hash, alloc_commit_node(r));
1063                 if (parse_commit_internal(odb_commit, 0, 0)) {
1064                         graph_report("failed to parse %s from object database",
1065                                      oid_to_hex(&cur_oid));
1066                         continue;
1067                 }
1068
1069                 if (!oideq(&get_commit_tree_in_graph_one(g, graph_commit)->object.oid,
1070                            get_commit_tree_oid(odb_commit)))
1071                         graph_report("root tree OID for commit %s in commit-graph is %s != %s",
1072                                      oid_to_hex(&cur_oid),
1073                                      oid_to_hex(get_commit_tree_oid(graph_commit)),
1074                                      oid_to_hex(get_commit_tree_oid(odb_commit)));
1075
1076                 graph_parents = graph_commit->parents;
1077                 odb_parents = odb_commit->parents;
1078
1079                 while (graph_parents) {
1080                         if (odb_parents == NULL) {
1081                                 graph_report("commit-graph parent list for commit %s is too long",
1082                                              oid_to_hex(&cur_oid));
1083                                 break;
1084                         }
1085
1086                         if (!oideq(&graph_parents->item->object.oid, &odb_parents->item->object.oid))
1087                                 graph_report("commit-graph parent for %s is %s != %s",
1088                                              oid_to_hex(&cur_oid),
1089                                              oid_to_hex(&graph_parents->item->object.oid),
1090                                              oid_to_hex(&odb_parents->item->object.oid));
1091
1092                         if (graph_parents->item->generation > max_generation)
1093                                 max_generation = graph_parents->item->generation;
1094
1095                         graph_parents = graph_parents->next;
1096                         odb_parents = odb_parents->next;
1097                 }
1098
1099                 if (odb_parents != NULL)
1100                         graph_report("commit-graph parent list for commit %s terminates early",
1101                                      oid_to_hex(&cur_oid));
1102
1103                 if (!graph_commit->generation) {
1104                         if (generation_zero == GENERATION_NUMBER_EXISTS)
1105                                 graph_report("commit-graph has generation number zero for commit %s, but non-zero elsewhere",
1106                                              oid_to_hex(&cur_oid));
1107                         generation_zero = GENERATION_ZERO_EXISTS;
1108                 } else if (generation_zero == GENERATION_ZERO_EXISTS)
1109                         graph_report("commit-graph has non-zero generation number for commit %s, but zero elsewhere",
1110                                      oid_to_hex(&cur_oid));
1111
1112                 if (generation_zero == GENERATION_ZERO_EXISTS)
1113                         continue;
1114
1115                 /*
1116                  * If one of our parents has generation GENERATION_NUMBER_MAX, then
1117                  * our generation is also GENERATION_NUMBER_MAX. Decrement to avoid
1118                  * extra logic in the following condition.
1119                  */
1120                 if (max_generation == GENERATION_NUMBER_MAX)
1121                         max_generation--;
1122
1123                 if (graph_commit->generation != max_generation + 1)
1124                         graph_report("commit-graph generation for commit %s is %u != %u",
1125                                      oid_to_hex(&cur_oid),
1126                                      graph_commit->generation,
1127                                      max_generation + 1);
1128
1129                 if (graph_commit->date != odb_commit->date)
1130                         graph_report("commit date for commit %s in commit-graph is %"PRItime" != %"PRItime,
1131                                      oid_to_hex(&cur_oid),
1132                                      graph_commit->date,
1133                                      odb_commit->date);
1134         }
1135         stop_progress(&progress);
1136
1137         return verify_commit_graph_error;
1138 }
1139
1140 void free_commit_graph(struct commit_graph *g)
1141 {
1142         if (!g)
1143                 return;
1144         if (g->graph_fd >= 0) {
1145                 munmap((void *)g->data, g->data_len);
1146                 g->data = NULL;
1147                 close(g->graph_fd);
1148         }
1149         free(g);
1150 }