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