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