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