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