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