git.oblomov.eu Git - git/blob - commit-graph.c

   1 #include "cache.h"
   2 #include "config.h"
   3 #include "dir.h"
   4 #include "git-compat-util.h"
   5 #include "lockfile.h"
   6 #include "pack.h"
   7 #include "packfile.h"
   8 #include "commit.h"
   9 #include "object.h"
  10 #include "refs.h"
  11 #include "revision.h"
  12 #include "sha1-lookup.h"
  13 #include "commit-graph.h"
  14 #include "object-store.h"
  15 #include "alloc.h"
  16 #include "hashmap.h"
  17 #include "replace-object.h"
  18 #include "progress.h"
  19
  20 #define GRAPH_SIGNATURE 0x43475048 /* "CGPH" */
  21 #define GRAPH_CHUNKID_OIDFANOUT 0x4f494446 /* "OIDF" */
  22 #define GRAPH_CHUNKID_OIDLOOKUP 0x4f49444c /* "OIDL" */
  23 #define GRAPH_CHUNKID_DATA 0x43444154 /* "CDAT" */
  24 #define GRAPH_CHUNKID_LARGEEDGES 0x45444745 /* "EDGE" */
  25
  26 #define GRAPH_DATA_WIDTH 36
  27
  28 #define GRAPH_VERSION_1 0x1
  29 #define GRAPH_VERSION GRAPH_VERSION_1
  30
  31 #define GRAPH_OID_VERSION_SHA1 1
  32 #define GRAPH_OID_LEN_SHA1 GIT_SHA1_RAWSZ
  33 #define GRAPH_OID_VERSION GRAPH_OID_VERSION_SHA1
  34 #define GRAPH_OID_LEN GRAPH_OID_LEN_SHA1
  35
  36 #define GRAPH_OCTOPUS_EDGES_NEEDED 0x80000000
  37 #define GRAPH_PARENT_MISSING 0x7fffffff
  38 #define GRAPH_EDGE_LAST_MASK 0x7fffffff
  39 #define GRAPH_PARENT_NONE 0x70000000
  40
  41 #define GRAPH_LAST_EDGE 0x80000000
  42
  43 #define GRAPH_HEADER_SIZE 8
  44 #define GRAPH_FANOUT_SIZE (4 * 256)
  45 #define GRAPH_CHUNKLOOKUP_WIDTH 12
  46 #define GRAPH_MIN_SIZE (GRAPH_HEADER_SIZE + 4 * GRAPH_CHUNKLOOKUP_WIDTH \
  47                         + GRAPH_FANOUT_SIZE + GRAPH_OID_LEN)
  48
  49 char *get_commit_graph_filename(const char *obj_dir)
  50 {
  51         return xstrfmt("%s/info/commit-graph", obj_dir);
  52 }
  53
  54 static struct commit_graph *alloc_commit_graph(void)
  55 {
  56         struct commit_graph *g = xcalloc(1, sizeof(*g));
  57         g->graph_fd = -1;
  58
  59         return g;
  60 }
  61
  62 extern int read_replace_refs;
  63
  64 static int commit_graph_compatible(struct repository *r)
  65 {
  66         if (!r->gitdir)
  67                 return 0;
  68
  69         if (read_replace_refs) {
  70                 prepare_replace_object(r);
  71                 if (hashmap_get_size(&r->objects->replace_map->map))
  72                         return 0;
  73         }
  74
  75         prepare_commit_graft(r);
  76         if (r->parsed_objects && r->parsed_objects->grafts_nr)
  77                 return 0;
  78         if (is_repository_shallow(r))
  79                 return 0;
  80
  81         return 1;
  82 }
  83
  84 struct commit_graph *load_commit_graph_one(const char *graph_file)
  85 {
  86         void *graph_map;
  87         const unsigned char *data, *chunk_lookup;
  88         size_t graph_size;
  89         struct stat st;
  90         uint32_t i;
  91         struct commit_graph *graph;
  92         int fd = git_open(graph_file);
  93         uint64_t last_chunk_offset;
  94         uint32_t last_chunk_id;
  95         uint32_t graph_signature;
  96         unsigned char graph_version, hash_version;
  97
  98         if (fd < 0)
  99                 return NULL;
 100         if (fstat(fd, &st)) {
 101                 close(fd);
 102                 return NULL;
 103         }
 104         graph_size = xsize_t(st.st_size);
 105
 106         if (graph_size < GRAPH_MIN_SIZE) {
 107                 close(fd);
 108                 die(_("graph file %s is too small"), graph_file);
 109         }
 110         graph_map = xmmap(NULL, graph_size, PROT_READ, MAP_PRIVATE, fd, 0);
 111         data = (const unsigned char *)graph_map;
 112
 113         graph_signature = get_be32(data);
 114         if (graph_signature != GRAPH_SIGNATURE) {
 115                 error(_("graph signature %X does not match signature %X"),
 116                       graph_signature, GRAPH_SIGNATURE);
 117                 goto cleanup_fail;
 118         }
 119
 120         graph_version = *(unsigned char*)(data + 4);
 121         if (graph_version != GRAPH_VERSION) {
 122                 error(_("graph version %X does not match version %X"),
 123                       graph_version, GRAPH_VERSION);
 124                 goto cleanup_fail;
 125         }
 126
 127         hash_version = *(unsigned char*)(data + 5);
 128         if (hash_version != GRAPH_OID_VERSION) {
 129                 error(_("hash version %X does not match version %X"),
 130                       hash_version, GRAPH_OID_VERSION);
 131                 goto cleanup_fail;
 132         }
 133
 134         graph = alloc_commit_graph();
 135
 136         graph->hash_len = GRAPH_OID_LEN;
 137         graph->num_chunks = *(unsigned char*)(data + 6);
 138         graph->graph_fd = fd;
 139         graph->data = graph_map;
 140         graph->data_len = graph_size;
 141
 142         last_chunk_id = 0;
 143         last_chunk_offset = 8;
 144         chunk_lookup = data + 8;
 145         for (i = 0; i < graph->num_chunks; i++) {
 146                 uint32_t chunk_id = get_be32(chunk_lookup + 0);
 147                 uint64_t chunk_offset = get_be64(chunk_lookup + 4);
 148                 int chunk_repeated = 0;
 149
 150                 chunk_lookup += GRAPH_CHUNKLOOKUP_WIDTH;
 151
 152                 if (chunk_offset > graph_size - GIT_MAX_RAWSZ) {
 153                         error(_("improper chunk offset %08x%08x"), (uint32_t)(chunk_offset >> 32),
 154                               (uint32_t)chunk_offset);
 155                         goto cleanup_fail;
 156                 }
 157
 158                 switch (chunk_id) {
 159                 case GRAPH_CHUNKID_OIDFANOUT:
 160                         if (graph->chunk_oid_fanout)
 161                                 chunk_repeated = 1;
 162                         else
 163                                 graph->chunk_oid_fanout = (uint32_t*)(data + chunk_offset);
 164                         break;
 165
 166                 case GRAPH_CHUNKID_OIDLOOKUP:
 167                         if (graph->chunk_oid_lookup)
 168                                 chunk_repeated = 1;
 169                         else
 170                                 graph->chunk_oid_lookup = data + chunk_offset;
 171                         break;
 172
 173                 case GRAPH_CHUNKID_DATA:
 174                         if (graph->chunk_commit_data)
 175                                 chunk_repeated = 1;
 176                         else
 177                                 graph->chunk_commit_data = data + chunk_offset;
 178                         break;
 179
 180                 case GRAPH_CHUNKID_LARGEEDGES:
 181                         if (graph->chunk_large_edges)
 182                                 chunk_repeated = 1;
 183                         else
 184                                 graph->chunk_large_edges = data + chunk_offset;
 185                         break;
 186                 }
 187
 188                 if (chunk_repeated) {
 189                         error(_("chunk id %08x appears multiple times"), chunk_id);
 190                         goto cleanup_fail;
 191                 }
 192
 193                 if (last_chunk_id == GRAPH_CHUNKID_OIDLOOKUP)
 194                 {
 195                         graph->num_commits = (chunk_offset - last_chunk_offset)
 196                                              / graph->hash_len;
 197                 }
 198
 199                 last_chunk_id = chunk_id;
 200                 last_chunk_offset = chunk_offset;
 201         }
 202
 203         return graph;
 204
 205 cleanup_fail:
 206         munmap(graph_map, graph_size);
 207         close(fd);
 208         exit(1);
 209 }
 210
 211 static void prepare_commit_graph_one(struct repository *r, const char *obj_dir)
 212 {
 213         char *graph_name;
 214
 215         if (r->objects->commit_graph)
 216                 return;
 217
 218         graph_name = get_commit_graph_filename(obj_dir);
 219         r->objects->commit_graph =
 220                 load_commit_graph_one(graph_name);
 221
 222         FREE_AND_NULL(graph_name);
 223 }
 224
 225 /*
 226  * Return 1 if commit_graph is non-NULL, and 0 otherwise.
 227  *
 228  * On the first invocation, this function attemps to load the commit
 229  * graph if the_repository is configured to have one.
 230  */
 231 static int prepare_commit_graph(struct repository *r)
 232 {
 233         struct object_directory *odb;
 234         int config_value;
 235
 236         if (r->objects->commit_graph_attempted)
 237                 return !!r->objects->commit_graph;
 238         r->objects->commit_graph_attempted = 1;
 239
 240         if (!git_env_bool(GIT_TEST_COMMIT_GRAPH, 0) &&
 241             (repo_config_get_bool(r, "core.commitgraph", &config_value) ||
 242             !config_value))
 243                 /*
 244                  * This repository is not configured to use commit graphs, so
 245                  * do not load one. (But report commit_graph_attempted anyway
 246                  * so that commit graph loading is not attempted again for this
 247                  * repository.)
 248                  */
 249                 return 0;
 250
 251         if (!commit_graph_compatible(r))
 252                 return 0;
 253
 254         prepare_alt_odb(r);
 255         for (odb = r->objects->odb;
 256              !r->objects->commit_graph && odb;
 257              odb = odb->next)
 258                 prepare_commit_graph_one(r, odb->path);
 259         return !!r->objects->commit_graph;
 260 }
 261
 262 int generation_numbers_enabled(struct repository *r)
 263 {
 264         uint32_t first_generation;
 265         struct commit_graph *g;
 266         if (!prepare_commit_graph(r))
 267                return 0;
 268
 269         g = r->objects->commit_graph;
 270
 271         if (!g->num_commits)
 272                 return 0;
 273
 274         first_generation = get_be32(g->chunk_commit_data +
 275                                     g->hash_len + 8) >> 2;
 276
 277         return !!first_generation;
 278 }
 279
 280 void close_commit_graph(struct repository *r)
 281 {
 282         free_commit_graph(r->objects->commit_graph);
 283         r->objects->commit_graph = NULL;
 284 }
 285
 286 static int bsearch_graph(struct commit_graph *g, struct object_id *oid, uint32_t *pos)
 287 {
 288         return bsearch_hash(oid->hash, g->chunk_oid_fanout,
 289                             g->chunk_oid_lookup, g->hash_len, pos);
 290 }
 291
 292 static struct commit_list **insert_parent_or_die(struct commit_graph *g,
 293                                                  uint64_t pos,
 294                                                  struct commit_list **pptr)
 295 {
 296         struct commit *c;
 297         struct object_id oid;
 298
 299         if (pos >= g->num_commits)
 300                 die("invalid parent position %"PRIu64, pos);
 301
 302         hashcpy(oid.hash, g->chunk_oid_lookup + g->hash_len * pos);
 303         c = lookup_commit(the_repository, &oid);
 304         if (!c)
 305                 die(_("could not find commit %s"), oid_to_hex(&oid));
 306         c->graph_pos = pos;
 307         return &commit_list_insert(c, pptr)->next;
 308 }
 309
 310 static void fill_commit_graph_info(struct commit *item, struct commit_graph *g, uint32_t pos)
 311 {
 312         const unsigned char *commit_data = g->chunk_commit_data + GRAPH_DATA_WIDTH * pos;
 313         item->graph_pos = pos;
 314         item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
 315 }
 316
 317 static int fill_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t pos)
 318 {
 319         uint32_t edge_value;
 320         uint32_t *parent_data_ptr;
 321         uint64_t date_low, date_high;
 322         struct commit_list **pptr;
 323         const unsigned char *commit_data = g->chunk_commit_data + (g->hash_len + 16) * pos;
 324
 325         item->object.parsed = 1;
 326         item->graph_pos = pos;
 327
 328         item->maybe_tree = NULL;
 329
 330         date_high = get_be32(commit_data + g->hash_len + 8) & 0x3;
 331         date_low = get_be32(commit_data + g->hash_len + 12);
 332         item->date = (timestamp_t)((date_high << 32) | date_low);
 333
 334         item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
 335
 336         pptr = &item->parents;
 337
 338         edge_value = get_be32(commit_data + g->hash_len);
 339         if (edge_value == GRAPH_PARENT_NONE)
 340                 return 1;
 341         pptr = insert_parent_or_die(g, edge_value, pptr);
 342
 343         edge_value = get_be32(commit_data + g->hash_len + 4);
 344         if (edge_value == GRAPH_PARENT_NONE)
 345                 return 1;
 346         if (!(edge_value & GRAPH_OCTOPUS_EDGES_NEEDED)) {
 347                 pptr = insert_parent_or_die(g, edge_value, pptr);
 348                 return 1;
 349         }
 350
 351         parent_data_ptr = (uint32_t*)(g->chunk_large_edges +
 352                           4 * (uint64_t)(edge_value & GRAPH_EDGE_LAST_MASK));
 353         do {
 354                 edge_value = get_be32(parent_data_ptr);
 355                 pptr = insert_parent_or_die(g,
 356                                             edge_value & GRAPH_EDGE_LAST_MASK,
 357                                             pptr);
 358                 parent_data_ptr++;
 359         } while (!(edge_value & GRAPH_LAST_EDGE));
 360
 361         return 1;
 362 }
 363
 364 static int find_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t *pos)
 365 {
 366         if (item->graph_pos != COMMIT_NOT_FROM_GRAPH) {
 367                 *pos = item->graph_pos;
 368                 return 1;
 369         } else {
 370                 return bsearch_graph(g, &(item->object.oid), pos);
 371         }
 372 }
 373
 374 static int parse_commit_in_graph_one(struct commit_graph *g, struct commit *item)
 375 {
 376         uint32_t pos;
 377
 378         if (item->object.parsed)
 379                 return 1;
 380
 381         if (find_commit_in_graph(item, g, &pos))
 382                 return fill_commit_in_graph(item, g, pos);
 383
 384         return 0;
 385 }
 386
 387 int parse_commit_in_graph(struct repository *r, struct commit *item)
 388 {
 389         if (!prepare_commit_graph(r))
 390                 return 0;
 391         return parse_commit_in_graph_one(r->objects->commit_graph, item);
 392 }
 393
 394 void load_commit_graph_info(struct repository *r, struct commit *item)
 395 {
 396         uint32_t pos;
 397         if (!prepare_commit_graph(r))
 398                 return;
 399         if (find_commit_in_graph(item, r->objects->commit_graph, &pos))
 400                 fill_commit_graph_info(item, r->objects->commit_graph, pos);
 401 }
 402
 403 static struct tree *load_tree_for_commit(struct commit_graph *g, struct commit *c)
 404 {
 405         struct object_id oid;
 406         const unsigned char *commit_data = g->chunk_commit_data +
 407                                            GRAPH_DATA_WIDTH * (c->graph_pos);
 408
 409         hashcpy(oid.hash, commit_data);
 410         c->maybe_tree = lookup_tree(the_repository, &oid);
 411
 412         return c->maybe_tree;
 413 }
 414
 415 static struct tree *get_commit_tree_in_graph_one(struct commit_graph *g,
 416                                                  const struct commit *c)
 417 {
 418         if (c->maybe_tree)
 419                 return c->maybe_tree;
 420         if (c->graph_pos == COMMIT_NOT_FROM_GRAPH)
 421                 BUG("get_commit_tree_in_graph_one called from non-commit-graph commit");
 422
 423         return load_tree_for_commit(g, (struct commit *)c);
 424 }
 425
 426 struct tree *get_commit_tree_in_graph(struct repository *r, const struct commit *c)
 427 {
 428         return get_commit_tree_in_graph_one(r->objects->commit_graph, c);
 429 }
 430
 431 static void write_graph_chunk_fanout(struct hashfile *f,
 432                                      struct commit **commits,
 433                                      int nr_commits)
 434 {
 435         int i, count = 0;
 436         struct commit **list = commits;
 437
 438         /*
 439          * Write the first-level table (the list is sorted,
 440          * but we use a 256-entry lookup to be able to avoid
 441          * having to do eight extra binary search iterations).
 442          */
 443         for (i = 0; i < 256; i++) {
 444                 while (count < nr_commits) {
 445                         if ((*list)->object.oid.hash[0] != i)
 446                                 break;
 447                         count++;
 448                         list++;
 449                 }
 450
 451                 hashwrite_be32(f, count);
 452         }
 453 }
 454
 455 static void write_graph_chunk_oids(struct hashfile *f, int hash_len,
 456                                    struct commit **commits, int nr_commits)
 457 {
 458         struct commit **list = commits;
 459         int count;
 460         for (count = 0; count < nr_commits; count++, list++)
 461                 hashwrite(f, (*list)->object.oid.hash, (int)hash_len);
 462 }
 463
 464 static const unsigned char *commit_to_sha1(size_t index, void *table)
 465 {
 466         struct commit **commits = table;
 467         return commits[index]->object.oid.hash;
 468 }
 469
 470 static void write_graph_chunk_data(struct hashfile *f, int hash_len,
 471                                    struct commit **commits, int nr_commits)
 472 {
 473         struct commit **list = commits;
 474         struct commit **last = commits + nr_commits;
 475         uint32_t num_extra_edges = 0;
 476
 477         while (list < last) {
 478                 struct commit_list *parent;
 479                 int edge_value;
 480                 uint32_t packedDate[2];
 481
 482                 parse_commit(*list);
 483                 hashwrite(f, get_commit_tree_oid(*list)->hash, hash_len);
 484
 485                 parent = (*list)->parents;
 486
 487                 if (!parent)
 488                         edge_value = GRAPH_PARENT_NONE;
 489                 else {
 490                         edge_value = sha1_pos(parent->item->object.oid.hash,
 491                                               commits,
 492                                               nr_commits,
 493                                               commit_to_sha1);
 494
 495                         if (edge_value < 0)
 496                                 edge_value = GRAPH_PARENT_MISSING;
 497                 }
 498
 499                 hashwrite_be32(f, edge_value);
 500
 501                 if (parent)
 502                         parent = parent->next;
 503
 504                 if (!parent)
 505                         edge_value = GRAPH_PARENT_NONE;
 506                 else if (parent->next)
 507                         edge_value = GRAPH_OCTOPUS_EDGES_NEEDED | num_extra_edges;
 508                 else {
 509                         edge_value = sha1_pos(parent->item->object.oid.hash,
 510                                               commits,
 511                                               nr_commits,
 512                                               commit_to_sha1);
 513                         if (edge_value < 0)
 514                                 edge_value = GRAPH_PARENT_MISSING;
 515                 }
 516
 517                 hashwrite_be32(f, edge_value);
 518
 519                 if (edge_value & GRAPH_OCTOPUS_EDGES_NEEDED) {
 520                         do {
 521                                 num_extra_edges++;
 522                                 parent = parent->next;
 523                         } while (parent);
 524                 }
 525
 526                 if (sizeof((*list)->date) > 4)
 527                         packedDate[0] = htonl(((*list)->date >> 32) & 0x3);
 528                 else
 529                         packedDate[0] = 0;
 530
 531                 packedDate[0] |= htonl((*list)->generation << 2);
 532
 533                 packedDate[1] = htonl((*list)->date);
 534                 hashwrite(f, packedDate, 8);
 535
 536                 list++;
 537         }
 538 }
 539
 540 static void write_graph_chunk_large_edges(struct hashfile *f,
 541                                           struct commit **commits,
 542                                           int nr_commits)
 543 {
 544         struct commit **list = commits;
 545         struct commit **last = commits + nr_commits;
 546         struct commit_list *parent;
 547
 548         while (list < last) {
 549                 int num_parents = 0;
 550                 for (parent = (*list)->parents; num_parents < 3 && parent;
 551                      parent = parent->next)
 552                         num_parents++;
 553
 554                 if (num_parents <= 2) {
 555                         list++;
 556                         continue;
 557                 }
 558
 559                 /* Since num_parents > 2, this initializer is safe. */
 560                 for (parent = (*list)->parents->next; parent; parent = parent->next) {
 561                         int edge_value = sha1_pos(parent->item->object.oid.hash,
 562                                                   commits,
 563                                                   nr_commits,
 564                                                   commit_to_sha1);
 565
 566                         if (edge_value < 0)
 567                                 edge_value = GRAPH_PARENT_MISSING;
 568                         else if (!parent->next)
 569                                 edge_value |= GRAPH_LAST_EDGE;
 570
 571                         hashwrite_be32(f, edge_value);
 572                 }
 573
 574                 list++;
 575         }
 576 }
 577
 578 static int commit_compare(const void *_a, const void *_b)
 579 {
 580         const struct object_id *a = (const struct object_id *)_a;
 581         const struct object_id *b = (const struct object_id *)_b;
 582         return oidcmp(a, b);
 583 }
 584
 585 struct packed_commit_list {
 586         struct commit **list;
 587         int nr;
 588         int alloc;
 589 };
 590
 591 struct packed_oid_list {
 592         struct object_id *list;
 593         int nr;
 594         int alloc;
 595         struct progress *progress;
 596         int progress_done;
 597 };
 598
 599 static int add_packed_commits(const struct object_id *oid,
 600                               struct packed_git *pack,
 601                               uint32_t pos,
 602                               void *data)
 603 {
 604         struct packed_oid_list *list = (struct packed_oid_list*)data;
 605         enum object_type type;
 606         off_t offset = nth_packed_object_offset(pack, pos);
 607         struct object_info oi = OBJECT_INFO_INIT;
 608
 609         if (list->progress)
 610                 display_progress(list->progress, ++list->progress_done);
 611
 612         oi.typep = &type;
 613         if (packed_object_info(the_repository, pack, offset, &oi) < 0)
 614                 die(_("unable to get type of object %s"), oid_to_hex(oid));
 615
 616         if (type != OBJ_COMMIT)
 617                 return 0;
 618
 619         ALLOC_GROW(list->list, list->nr + 1, list->alloc);
 620         oidcpy(&(list->list[list->nr]), oid);
 621         list->nr++;
 622
 623         return 0;
 624 }
 625
 626 static void add_missing_parents(struct packed_oid_list *oids, struct commit *commit)
 627 {
 628         struct commit_list *parent;
 629         for (parent = commit->parents; parent; parent = parent->next) {
 630                 if (!(parent->item->object.flags & UNINTERESTING)) {
 631                         ALLOC_GROW(oids->list, oids->nr + 1, oids->alloc);
 632                         oidcpy(&oids->list[oids->nr], &(parent->item->object.oid));
 633                         oids->nr++;
 634                         parent->item->object.flags |= UNINTERESTING;
 635                 }
 636         }
 637 }
 638
 639 static void close_reachable(struct packed_oid_list *oids, int report_progress)
 640 {
 641         int i, j;
 642         struct commit *commit;
 643         struct progress *progress = NULL;
 644
 645         if (report_progress)
 646                 progress = start_delayed_progress(
 647                         _("Loading known commits in commit graph"), j = 0);
 648         for (i = 0; i < oids->nr; i++) {
 649                 display_progress(progress, ++j);
 650                 commit = lookup_commit(the_repository, &oids->list[i]);
 651                 if (commit)
 652                         commit->object.flags |= UNINTERESTING;
 653         }
 654         stop_progress(&progress);
 655
 656         /*
 657          * As this loop runs, oids->nr may grow, but not more
 658          * than the number of missing commits in the reachable
 659          * closure.
 660          */
 661         if (report_progress)
 662                 progress = start_delayed_progress(
 663                         _("Expanding reachable commits in commit graph"), j = 0);
 664         for (i = 0; i < oids->nr; i++) {
 665                 display_progress(progress, ++j);
 666                 commit = lookup_commit(the_repository, &oids->list[i]);
 667
 668                 if (commit && !parse_commit(commit))
 669                         add_missing_parents(oids, commit);
 670         }
 671         stop_progress(&progress);
 672
 673         if (report_progress)
 674                 progress = start_delayed_progress(
 675                         _("Clearing commit marks in commit graph"), j = 0);
 676         for (i = 0; i < oids->nr; i++) {
 677                 display_progress(progress, ++j);
 678                 commit = lookup_commit(the_repository, &oids->list[i]);
 679
 680                 if (commit)
 681                         commit->object.flags &= ~UNINTERESTING;
 682         }
 683         stop_progress(&progress);
 684 }
 685
 686 static void compute_generation_numbers(struct packed_commit_list* commits,
 687                                        int report_progress)
 688 {
 689         int i;
 690         struct commit_list *list = NULL;
 691         struct progress *progress = NULL;
 692
 693         if (report_progress)
 694                 progress = start_progress(
 695                         _("Computing commit graph generation numbers"),
 696                         commits->nr);
 697         for (i = 0; i < commits->nr; i++) {
 698                 display_progress(progress, i + 1);
 699                 if (commits->list[i]->generation != GENERATION_NUMBER_INFINITY &&
 700                     commits->list[i]->generation != GENERATION_NUMBER_ZERO)
 701                         continue;
 702
 703                 commit_list_insert(commits->list[i], &list);
 704                 while (list) {
 705                         struct commit *current = list->item;
 706                         struct commit_list *parent;
 707                         int all_parents_computed = 1;
 708                         uint32_t max_generation = 0;
 709
 710                         for (parent = current->parents; parent; parent = parent->next) {
 711                                 if (parent->item->generation == GENERATION_NUMBER_INFINITY ||
 712                                     parent->item->generation == GENERATION_NUMBER_ZERO) {
 713                                         all_parents_computed = 0;
 714                                         commit_list_insert(parent->item, &list);
 715                                         break;
 716                                 } else if (parent->item->generation > max_generation) {
 717                                         max_generation = parent->item->generation;
 718                                 }
 719                         }
 720
 721                         if (all_parents_computed) {
 722                                 current->generation = max_generation + 1;
 723                                 pop_commit(&list);
 724
 725                                 if (current->generation > GENERATION_NUMBER_MAX)
 726                                         current->generation = GENERATION_NUMBER_MAX;
 727                         }
 728                 }
 729         }
 730         stop_progress(&progress);
 731 }
 732
 733 static int add_ref_to_list(const char *refname,
 734                            const struct object_id *oid,
 735                            int flags, void *cb_data)
 736 {
 737         struct string_list *list = (struct string_list *)cb_data;
 738
 739         string_list_append(list, oid_to_hex(oid));
 740         return 0;
 741 }
 742
 743 void write_commit_graph_reachable(const char *obj_dir, int append,
 744                                   int report_progress)
 745 {
 746         struct string_list list = STRING_LIST_INIT_DUP;
 747
 748         for_each_ref(add_ref_to_list, &list);
 749         write_commit_graph(obj_dir, NULL, &list, append, report_progress);
 750
 751         string_list_clear(&list, 0);
 752 }
 753
 754 void write_commit_graph(const char *obj_dir,
 755                         struct string_list *pack_indexes,
 756                         struct string_list *commit_hex,
 757                         int append, int report_progress)
 758 {
 759         struct packed_oid_list oids;
 760         struct packed_commit_list commits;
 761         struct hashfile *f;
 762         uint32_t i, count_distinct = 0;
 763         char *graph_name;
 764         struct lock_file lk = LOCK_INIT;
 765         uint32_t chunk_ids[5];
 766         uint64_t chunk_offsets[5];
 767         int num_chunks;
 768         int num_extra_edges;
 769         struct commit_list *parent;
 770         struct progress *progress = NULL;
 771
 772         if (!commit_graph_compatible(the_repository))
 773                 return;
 774
 775         oids.nr = 0;
 776         oids.alloc = approximate_object_count() / 32;
 777         oids.progress = NULL;
 778         oids.progress_done = 0;
 779
 780         if (append) {
 781                 prepare_commit_graph_one(the_repository, obj_dir);
 782                 if (the_repository->objects->commit_graph)
 783                         oids.alloc += the_repository->objects->commit_graph->num_commits;
 784         }
 785
 786         if (oids.alloc < 1024)
 787                 oids.alloc = 1024;
 788         ALLOC_ARRAY(oids.list, oids.alloc);
 789
 790         if (append && the_repository->objects->commit_graph) {
 791                 struct commit_graph *commit_graph =
 792                         the_repository->objects->commit_graph;
 793                 for (i = 0; i < commit_graph->num_commits; i++) {
 794                         const unsigned char *hash = commit_graph->chunk_oid_lookup +
 795                                 commit_graph->hash_len * i;
 796                         hashcpy(oids.list[oids.nr++].hash, hash);
 797                 }
 798         }
 799
 800         if (pack_indexes) {
 801                 struct strbuf packname = STRBUF_INIT;
 802                 int dirlen;
 803                 strbuf_addf(&packname, "%s/pack/", obj_dir);
 804                 dirlen = packname.len;
 805                 if (report_progress) {
 806                         oids.progress = start_delayed_progress(
 807                                 _("Finding commits for commit graph"), 0);
 808                         oids.progress_done = 0;
 809                 }
 810                 for (i = 0; i < pack_indexes->nr; i++) {
 811                         struct packed_git *p;
 812                         strbuf_setlen(&packname, dirlen);
 813                         strbuf_addstr(&packname, pack_indexes->items[i].string);
 814                         p = add_packed_git(packname.buf, packname.len, 1);
 815                         if (!p)
 816                                 die(_("error adding pack %s"), packname.buf);
 817                         if (open_pack_index(p))
 818                                 die(_("error opening index for %s"), packname.buf);
 819                         for_each_object_in_pack(p, add_packed_commits, &oids, 0);
 820                         close_pack(p);
 821                         free(p);
 822                 }
 823                 stop_progress(&oids.progress);
 824                 strbuf_release(&packname);
 825         }
 826
 827         if (commit_hex) {
 828                 if (report_progress)
 829                         progress = start_delayed_progress(
 830                                 _("Finding commits for commit graph"),
 831                                 commit_hex->nr);
 832                 for (i = 0; i < commit_hex->nr; i++) {
 833                         const char *end;
 834                         struct object_id oid;
 835                         struct commit *result;
 836
 837                         display_progress(progress, i + 1);
 838                         if (commit_hex->items[i].string &&
 839                             parse_oid_hex(commit_hex->items[i].string, &oid, &end))
 840                                 continue;
 841
 842                         result = lookup_commit_reference_gently(the_repository, &oid, 1);
 843
 844                         if (result) {
 845                                 ALLOC_GROW(oids.list, oids.nr + 1, oids.alloc);
 846                                 oidcpy(&oids.list[oids.nr], &(result->object.oid));
 847                                 oids.nr++;
 848                         }
 849                 }
 850                 stop_progress(&progress);
 851         }
 852
 853         if (!pack_indexes && !commit_hex) {
 854                 if (report_progress)
 855                         oids.progress = start_delayed_progress(
 856                                 _("Finding commits for commit graph"), 0);
 857                 for_each_packed_object(add_packed_commits, &oids, 0);
 858                 stop_progress(&oids.progress);
 859         }
 860
 861         close_reachable(&oids, report_progress);
 862
 863         QSORT(oids.list, oids.nr, commit_compare);
 864
 865         count_distinct = 1;
 866         for (i = 1; i < oids.nr; i++) {
 867                 if (!oideq(&oids.list[i - 1], &oids.list[i]))
 868                         count_distinct++;
 869         }
 870
 871         if (count_distinct >= GRAPH_PARENT_MISSING)
 872                 die(_("the commit graph format cannot write %d commits"), count_distinct);
 873
 874         commits.nr = 0;
 875         commits.alloc = count_distinct;
 876         ALLOC_ARRAY(commits.list, commits.alloc);
 877
 878         num_extra_edges = 0;
 879         for (i = 0; i < oids.nr; i++) {
 880                 int num_parents = 0;
 881                 if (i > 0 && oideq(&oids.list[i - 1], &oids.list[i]))
 882                         continue;
 883
 884                 commits.list[commits.nr] = lookup_commit(the_repository, &oids.list[i]);
 885                 parse_commit(commits.list[commits.nr]);
 886
 887                 for (parent = commits.list[commits.nr]->parents;
 888                      parent; parent = parent->next)
 889                         num_parents++;
 890
 891                 if (num_parents > 2)
 892                         num_extra_edges += num_parents - 1;
 893
 894                 commits.nr++;
 895         }
 896         num_chunks = num_extra_edges ? 4 : 3;
 897
 898         if (commits.nr >= GRAPH_PARENT_MISSING)
 899                 die(_("too many commits to write graph"));
 900
 901         compute_generation_numbers(&commits, report_progress);
 902
 903         graph_name = get_commit_graph_filename(obj_dir);
 904         if (safe_create_leading_directories(graph_name)) {
 905                 UNLEAK(graph_name);
 906                 die_errno(_("unable to create leading directories of %s"),
 907                           graph_name);
 908         }
 909
 910         hold_lock_file_for_update(&lk, graph_name, LOCK_DIE_ON_ERROR);
 911         f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
 912
 913         hashwrite_be32(f, GRAPH_SIGNATURE);
 914
 915         hashwrite_u8(f, GRAPH_VERSION);
 916         hashwrite_u8(f, GRAPH_OID_VERSION);
 917         hashwrite_u8(f, num_chunks);
 918         hashwrite_u8(f, 0); /* unused padding byte */
 919
 920         chunk_ids[0] = GRAPH_CHUNKID_OIDFANOUT;
 921         chunk_ids[1] = GRAPH_CHUNKID_OIDLOOKUP;
 922         chunk_ids[2] = GRAPH_CHUNKID_DATA;
 923         if (num_extra_edges)
 924                 chunk_ids[3] = GRAPH_CHUNKID_LARGEEDGES;
 925         else
 926                 chunk_ids[3] = 0;
 927         chunk_ids[4] = 0;
 928
 929         chunk_offsets[0] = 8 + (num_chunks + 1) * GRAPH_CHUNKLOOKUP_WIDTH;
 930         chunk_offsets[1] = chunk_offsets[0] + GRAPH_FANOUT_SIZE;
 931         chunk_offsets[2] = chunk_offsets[1] + GRAPH_OID_LEN * commits.nr;
 932         chunk_offsets[3] = chunk_offsets[2] + (GRAPH_OID_LEN + 16) * commits.nr;
 933         chunk_offsets[4] = chunk_offsets[3] + 4 * num_extra_edges;
 934
 935         for (i = 0; i <= num_chunks; i++) {
 936                 uint32_t chunk_write[3];
 937
 938                 chunk_write[0] = htonl(chunk_ids[i]);
 939                 chunk_write[1] = htonl(chunk_offsets[i] >> 32);
 940                 chunk_write[2] = htonl(chunk_offsets[i] & 0xffffffff);
 941                 hashwrite(f, chunk_write, 12);
 942         }
 943
 944         write_graph_chunk_fanout(f, commits.list, commits.nr);
 945         write_graph_chunk_oids(f, GRAPH_OID_LEN, commits.list, commits.nr);
 946         write_graph_chunk_data(f, GRAPH_OID_LEN, commits.list, commits.nr);
 947         write_graph_chunk_large_edges(f, commits.list, commits.nr);
 948
 949         close_commit_graph(the_repository);
 950         finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_FSYNC);
 951         commit_lock_file(&lk);
 952
 953         free(graph_name);
 954         free(commits.list);
 955         free(oids.list);
 956 }
 957
 958 #define VERIFY_COMMIT_GRAPH_ERROR_HASH 2
 959 static int verify_commit_graph_error;
 960
 961 static void graph_report(const char *fmt, ...)
 962 {
 963         va_list ap;
 964
 965         verify_commit_graph_error = 1;
 966         va_start(ap, fmt);
 967         vfprintf(stderr, fmt, ap);
 968         fprintf(stderr, "\n");
 969         va_end(ap);
 970 }
 971
 972 #define GENERATION_ZERO_EXISTS 1
 973 #define GENERATION_NUMBER_EXISTS 2
 974
 975 int verify_commit_graph(struct repository *r, struct commit_graph *g)
 976 {
 977         uint32_t i, cur_fanout_pos = 0;
 978         struct object_id prev_oid, cur_oid, checksum;
 979         int generation_zero = 0;
 980         struct hashfile *f;
 981         int devnull;
 982         struct progress *progress = NULL;
 983
 984         if (!g) {
 985                 graph_report("no commit-graph file loaded");
 986                 return 1;
 987         }
 988
 989         verify_commit_graph_error = 0;
 990
 991         if (!g->chunk_oid_fanout)
 992                 graph_report("commit-graph is missing the OID Fanout chunk");
 993         if (!g->chunk_oid_lookup)
 994                 graph_report("commit-graph is missing the OID Lookup chunk");
 995         if (!g->chunk_commit_data)
 996                 graph_report("commit-graph is missing the Commit Data chunk");
 997
 998         if (verify_commit_graph_error)
 999                 return verify_commit_graph_error;
1000
1001         devnull = open("/dev/null", O_WRONLY);
1002         f = hashfd(devnull, NULL);
1003         hashwrite(f, g->data, g->data_len - g->hash_len);
1004         finalize_hashfile(f, checksum.hash, CSUM_CLOSE);
1005         if (!hasheq(checksum.hash, g->data + g->data_len - g->hash_len)) {
1006                 graph_report(_("the commit-graph file has incorrect checksum and is likely corrupt"));
1007                 verify_commit_graph_error = VERIFY_COMMIT_GRAPH_ERROR_HASH;
1008         }
1009
1010         for (i = 0; i < g->num_commits; i++) {
1011                 struct commit *graph_commit;
1012
1013                 hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
1014
1015                 if (i && oidcmp(&prev_oid, &cur_oid) >= 0)
1016                         graph_report("commit-graph has incorrect OID order: %s then %s",
1017                                      oid_to_hex(&prev_oid),
1018                                      oid_to_hex(&cur_oid));
1019
1020                 oidcpy(&prev_oid, &cur_oid);
1021
1022                 while (cur_oid.hash[0] > cur_fanout_pos) {
1023                         uint32_t fanout_value = get_be32(g->chunk_oid_fanout + cur_fanout_pos);
1024
1025                         if (i != fanout_value)
1026                                 graph_report("commit-graph has incorrect fanout value: fanout[%d] = %u != %u",
1027                                              cur_fanout_pos, fanout_value, i);
1028                         cur_fanout_pos++;
1029                 }
1030
1031                 graph_commit = lookup_commit(r, &cur_oid);
1032                 if (!parse_commit_in_graph_one(g, graph_commit))
1033                         graph_report("failed to parse %s from commit-graph",
1034                                      oid_to_hex(&cur_oid));
1035         }
1036
1037         while (cur_fanout_pos < 256) {
1038                 uint32_t fanout_value = get_be32(g->chunk_oid_fanout + cur_fanout_pos);
1039
1040                 if (g->num_commits != fanout_value)
1041                         graph_report("commit-graph has incorrect fanout value: fanout[%d] = %u != %u",
1042                                      cur_fanout_pos, fanout_value, i);
1043
1044                 cur_fanout_pos++;
1045         }
1046
1047         if (verify_commit_graph_error & ~VERIFY_COMMIT_GRAPH_ERROR_HASH)
1048                 return verify_commit_graph_error;
1049
1050         progress = start_progress(_("Verifying commits in commit graph"),
1051                                   g->num_commits);
1052         for (i = 0; i < g->num_commits; i++) {
1053                 struct commit *graph_commit, *odb_commit;
1054                 struct commit_list *graph_parents, *odb_parents;
1055                 uint32_t max_generation = 0;
1056
1057                 display_progress(progress, i + 1);
1058                 hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
1059
1060                 graph_commit = lookup_commit(r, &cur_oid);
1061                 odb_commit = (struct commit *)create_object(r, cur_oid.hash, alloc_commit_node(r));
1062                 if (parse_commit_internal(odb_commit, 0, 0)) {
1063                         graph_report("failed to parse %s from object database",
1064                                      oid_to_hex(&cur_oid));
1065                         continue;
1066                 }
1067
1068                 if (!oideq(&get_commit_tree_in_graph_one(g, graph_commit)->object.oid,
1069                            get_commit_tree_oid(odb_commit)))
1070                         graph_report("root tree OID for commit %s in commit-graph is %s != %s",
1071                                      oid_to_hex(&cur_oid),
1072                                      oid_to_hex(get_commit_tree_oid(graph_commit)),
1073                                      oid_to_hex(get_commit_tree_oid(odb_commit)));
1074
1075                 graph_parents = graph_commit->parents;
1076                 odb_parents = odb_commit->parents;
1077
1078                 while (graph_parents) {
1079                         if (odb_parents == NULL) {
1080                                 graph_report("commit-graph parent list for commit %s is too long",
1081                                              oid_to_hex(&cur_oid));
1082                                 break;
1083                         }
1084
1085                         if (!oideq(&graph_parents->item->object.oid, &odb_parents->item->object.oid))
1086                                 graph_report("commit-graph parent for %s is %s != %s",
1087                                              oid_to_hex(&cur_oid),
1088                                              oid_to_hex(&graph_parents->item->object.oid),
1089                                              oid_to_hex(&odb_parents->item->object.oid));
1090
1091                         if (graph_parents->item->generation > max_generation)
1092                                 max_generation = graph_parents->item->generation;
1093
1094                         graph_parents = graph_parents->next;
1095                         odb_parents = odb_parents->next;
1096                 }
1097
1098                 if (odb_parents != NULL)
1099                         graph_report("commit-graph parent list for commit %s terminates early",
1100                                      oid_to_hex(&cur_oid));
1101
1102                 if (!graph_commit->generation) {
1103                         if (generation_zero == GENERATION_NUMBER_EXISTS)
1104                                 graph_report("commit-graph has generation number zero for commit %s, but non-zero elsewhere",
1105                                              oid_to_hex(&cur_oid));
1106                         generation_zero = GENERATION_ZERO_EXISTS;
1107                 } else if (generation_zero == GENERATION_ZERO_EXISTS)
1108                         graph_report("commit-graph has non-zero generation number for commit %s, but zero elsewhere",
1109                                      oid_to_hex(&cur_oid));
1110
1111                 if (generation_zero == GENERATION_ZERO_EXISTS)
1112                         continue;
1113
1114                 /*
1115                  * If one of our parents has generation GENERATION_NUMBER_MAX, then
1116                  * our generation is also GENERATION_NUMBER_MAX. Decrement to avoid
1117                  * extra logic in the following condition.
1118                  */
1119                 if (max_generation == GENERATION_NUMBER_MAX)
1120                         max_generation--;
1121
1122                 if (graph_commit->generation != max_generation + 1)
1123                         graph_report("commit-graph generation for commit %s is %u != %u",
1124                                      oid_to_hex(&cur_oid),
1125                                      graph_commit->generation,
1126                                      max_generation + 1);
1127
1128                 if (graph_commit->date != odb_commit->date)
1129                         graph_report("commit date for commit %s in commit-graph is %"PRItime" != %"PRItime,
1130                                      oid_to_hex(&cur_oid),
1131                                      graph_commit->date,
1132                                      odb_commit->date);
1133         }
1134         stop_progress(&progress);
1135
1136         return verify_commit_graph_error;
1137 }
1138
1139 void free_commit_graph(struct commit_graph *g)
1140 {
1141         if (!g)
1142                 return;
1143         if (g->graph_fd >= 0) {
1144                 munmap((void *)g->data, g->data_len);
1145                 g->data = NULL;
1146                 close(g->graph_fd);
1147         }
1148         free(g);
1149 }