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;
 599         struct commit *commit;
 600         struct progress *progress = NULL;
 601         int j = 0;
 602
 603         if (report_progress)
 604                 progress = start_delayed_progress(
 605                         _("Annotating commits in commit graph"), 0);
 606         for (i = 0; i < oids->nr; i++) {
 607                 display_progress(progress, ++j);
 608                 commit = lookup_commit(the_repository, &oids->list[i]);
 609                 if (commit)
 610                         commit->object.flags |= UNINTERESTING;
 611         }
 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         for (i = 0; i < oids->nr; i++) {
 619                 display_progress(progress, ++j);
 620                 commit = lookup_commit(the_repository, &oids->list[i]);
 621
 622                 if (commit && !parse_commit(commit))
 623                         add_missing_parents(oids, commit);
 624         }
 625
 626         for (i = 0; i < oids->nr; i++) {
 627                 display_progress(progress, ++j);
 628                 commit = lookup_commit(the_repository, &oids->list[i]);
 629
 630                 if (commit)
 631                         commit->object.flags &= ~UNINTERESTING;
 632         }
 633         stop_progress(&progress);
 634 }
 635
 636 static void compute_generation_numbers(struct packed_commit_list* commits,
 637                                        int report_progress)
 638 {
 639         int i;
 640         struct commit_list *list = NULL;
 641         struct progress *progress = NULL;
 642
 643         if (report_progress)
 644                 progress = start_progress(
 645                         _("Computing commit graph generation numbers"),
 646                         commits->nr);
 647         for (i = 0; i < commits->nr; i++) {
 648                 display_progress(progress, i + 1);
 649                 if (commits->list[i]->generation != GENERATION_NUMBER_INFINITY &&
 650                     commits->list[i]->generation != GENERATION_NUMBER_ZERO)
 651                         continue;
 652
 653                 commit_list_insert(commits->list[i], &list);
 654                 while (list) {
 655                         struct commit *current = list->item;
 656                         struct commit_list *parent;
 657                         int all_parents_computed = 1;
 658                         uint32_t max_generation = 0;
 659
 660                         for (parent = current->parents; parent; parent = parent->next) {
 661                                 if (parent->item->generation == GENERATION_NUMBER_INFINITY ||
 662                                     parent->item->generation == GENERATION_NUMBER_ZERO) {
 663                                         all_parents_computed = 0;
 664                                         commit_list_insert(parent->item, &list);
 665                                         break;
 666                                 } else if (parent->item->generation > max_generation) {
 667                                         max_generation = parent->item->generation;
 668                                 }
 669                         }
 670
 671                         if (all_parents_computed) {
 672                                 current->generation = max_generation + 1;
 673                                 pop_commit(&list);
 674
 675                                 if (current->generation > GENERATION_NUMBER_MAX)
 676                                         current->generation = GENERATION_NUMBER_MAX;
 677                         }
 678                 }
 679         }
 680         stop_progress(&progress);
 681 }
 682
 683 static int add_ref_to_list(const char *refname,
 684                            const struct object_id *oid,
 685                            int flags, void *cb_data)
 686 {
 687         struct string_list *list = (struct string_list *)cb_data;
 688
 689         string_list_append(list, oid_to_hex(oid));
 690         return 0;
 691 }
 692
 693 void write_commit_graph_reachable(const char *obj_dir, int append,
 694                                   int report_progress)
 695 {
 696         struct string_list list;
 697
 698         string_list_init(&list, 1);
 699         for_each_ref(add_ref_to_list, &list);
 700         write_commit_graph(obj_dir, NULL, &list, append, report_progress);
 701 }
 702
 703 void write_commit_graph(const char *obj_dir,
 704                         struct string_list *pack_indexes,
 705                         struct string_list *commit_hex,
 706                         int append, int report_progress)
 707 {
 708         struct packed_oid_list oids;
 709         struct packed_commit_list commits;
 710         struct hashfile *f;
 711         uint32_t i, count_distinct = 0;
 712         char *graph_name;
 713         struct lock_file lk = LOCK_INIT;
 714         uint32_t chunk_ids[5];
 715         uint64_t chunk_offsets[5];
 716         int num_chunks;
 717         int num_extra_edges;
 718         struct commit_list *parent;
 719         struct progress *progress = NULL;
 720
 721         oids.nr = 0;
 722         oids.alloc = approximate_object_count() / 4;
 723         oids.progress = NULL;
 724         oids.progress_done = 0;
 725
 726         if (append) {
 727                 prepare_commit_graph_one(the_repository, obj_dir);
 728                 if (the_repository->objects->commit_graph)
 729                         oids.alloc += the_repository->objects->commit_graph->num_commits;
 730         }
 731
 732         if (oids.alloc < 1024)
 733                 oids.alloc = 1024;
 734         ALLOC_ARRAY(oids.list, oids.alloc);
 735
 736         if (append && the_repository->objects->commit_graph) {
 737                 struct commit_graph *commit_graph =
 738                         the_repository->objects->commit_graph;
 739                 for (i = 0; i < commit_graph->num_commits; i++) {
 740                         const unsigned char *hash = commit_graph->chunk_oid_lookup +
 741                                 commit_graph->hash_len * i;
 742                         hashcpy(oids.list[oids.nr++].hash, hash);
 743                 }
 744         }
 745
 746         if (pack_indexes) {
 747                 struct strbuf packname = STRBUF_INIT;
 748                 int dirlen;
 749                 strbuf_addf(&packname, "%s/pack/", obj_dir);
 750                 dirlen = packname.len;
 751                 if (report_progress) {
 752                         oids.progress = start_delayed_progress(
 753                                 _("Finding commits for commit graph"), 0);
 754                         oids.progress_done = 0;
 755                 }
 756                 for (i = 0; i < pack_indexes->nr; i++) {
 757                         struct packed_git *p;
 758                         strbuf_setlen(&packname, dirlen);
 759                         strbuf_addstr(&packname, pack_indexes->items[i].string);
 760                         p = add_packed_git(packname.buf, packname.len, 1);
 761                         if (!p)
 762                                 die(_("error adding pack %s"), packname.buf);
 763                         if (open_pack_index(p))
 764                                 die(_("error opening index for %s"), packname.buf);
 765                         for_each_object_in_pack(p, add_packed_commits, &oids, 0);
 766                         close_pack(p);
 767                 }
 768                 stop_progress(&oids.progress);
 769                 strbuf_release(&packname);
 770         }
 771
 772         if (commit_hex) {
 773                 if (report_progress)
 774                         progress = start_delayed_progress(
 775                                 _("Finding commits for commit graph"),
 776                                 commit_hex->nr);
 777                 for (i = 0; i < commit_hex->nr; i++) {
 778                         const char *end;
 779                         struct object_id oid;
 780                         struct commit *result;
 781
 782                         display_progress(progress, i + 1);
 783                         if (commit_hex->items[i].string &&
 784                             parse_oid_hex(commit_hex->items[i].string, &oid, &end))
 785                                 continue;
 786
 787                         result = lookup_commit_reference_gently(the_repository, &oid, 1);
 788
 789                         if (result) {
 790                                 ALLOC_GROW(oids.list, oids.nr + 1, oids.alloc);
 791                                 oidcpy(&oids.list[oids.nr], &(result->object.oid));
 792                                 oids.nr++;
 793                         }
 794                 }
 795                 stop_progress(&progress);
 796         }
 797
 798         if (!pack_indexes && !commit_hex) {
 799                 if (report_progress)
 800                         oids.progress = start_delayed_progress(
 801                                 _("Finding commits for commit graph"), 0);
 802                 for_each_packed_object(add_packed_commits, &oids, 0);
 803                 stop_progress(&oids.progress);
 804         }
 805
 806         close_reachable(&oids, report_progress);
 807
 808         QSORT(oids.list, oids.nr, commit_compare);
 809
 810         count_distinct = 1;
 811         for (i = 1; i < oids.nr; i++) {
 812                 if (oidcmp(&oids.list[i-1], &oids.list[i]))
 813                         count_distinct++;
 814         }
 815
 816         if (count_distinct >= GRAPH_PARENT_MISSING)
 817                 die(_("the commit graph format cannot write %d commits"), count_distinct);
 818
 819         commits.nr = 0;
 820         commits.alloc = count_distinct;
 821         ALLOC_ARRAY(commits.list, commits.alloc);
 822
 823         num_extra_edges = 0;
 824         for (i = 0; i < oids.nr; i++) {
 825                 int num_parents = 0;
 826                 if (i > 0 && !oidcmp(&oids.list[i-1], &oids.list[i]))
 827                         continue;
 828
 829                 commits.list[commits.nr] = lookup_commit(the_repository, &oids.list[i]);
 830                 parse_commit(commits.list[commits.nr]);
 831
 832                 for (parent = commits.list[commits.nr]->parents;
 833                      parent; parent = parent->next)
 834                         num_parents++;
 835
 836                 if (num_parents > 2)
 837                         num_extra_edges += num_parents - 1;
 838
 839                 commits.nr++;
 840         }
 841         num_chunks = num_extra_edges ? 4 : 3;
 842
 843         if (commits.nr >= GRAPH_PARENT_MISSING)
 844                 die(_("too many commits to write graph"));
 845
 846         compute_generation_numbers(&commits, report_progress);
 847
 848         graph_name = get_commit_graph_filename(obj_dir);
 849         if (safe_create_leading_directories(graph_name))
 850                 die_errno(_("unable to create leading directories of %s"),
 851                           graph_name);
 852
 853         hold_lock_file_for_update(&lk, graph_name, LOCK_DIE_ON_ERROR);
 854         f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
 855
 856         hashwrite_be32(f, GRAPH_SIGNATURE);
 857
 858         hashwrite_u8(f, GRAPH_VERSION);
 859         hashwrite_u8(f, GRAPH_OID_VERSION);
 860         hashwrite_u8(f, num_chunks);
 861         hashwrite_u8(f, 0); /* unused padding byte */
 862
 863         chunk_ids[0] = GRAPH_CHUNKID_OIDFANOUT;
 864         chunk_ids[1] = GRAPH_CHUNKID_OIDLOOKUP;
 865         chunk_ids[2] = GRAPH_CHUNKID_DATA;
 866         if (num_extra_edges)
 867                 chunk_ids[3] = GRAPH_CHUNKID_LARGEEDGES;
 868         else
 869                 chunk_ids[3] = 0;
 870         chunk_ids[4] = 0;
 871
 872         chunk_offsets[0] = 8 + (num_chunks + 1) * GRAPH_CHUNKLOOKUP_WIDTH;
 873         chunk_offsets[1] = chunk_offsets[0] + GRAPH_FANOUT_SIZE;
 874         chunk_offsets[2] = chunk_offsets[1] + GRAPH_OID_LEN * commits.nr;
 875         chunk_offsets[3] = chunk_offsets[2] + (GRAPH_OID_LEN + 16) * commits.nr;
 876         chunk_offsets[4] = chunk_offsets[3] + 4 * num_extra_edges;
 877
 878         for (i = 0; i <= num_chunks; i++) {
 879                 uint32_t chunk_write[3];
 880
 881                 chunk_write[0] = htonl(chunk_ids[i]);
 882                 chunk_write[1] = htonl(chunk_offsets[i] >> 32);
 883                 chunk_write[2] = htonl(chunk_offsets[i] & 0xffffffff);
 884                 hashwrite(f, chunk_write, 12);
 885         }
 886
 887         write_graph_chunk_fanout(f, commits.list, commits.nr);
 888         write_graph_chunk_oids(f, GRAPH_OID_LEN, commits.list, commits.nr);
 889         write_graph_chunk_data(f, GRAPH_OID_LEN, commits.list, commits.nr);
 890         write_graph_chunk_large_edges(f, commits.list, commits.nr);
 891
 892         close_commit_graph();
 893         finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_FSYNC);
 894         commit_lock_file(&lk);
 895
 896         free(oids.list);
 897         oids.alloc = 0;
 898         oids.nr = 0;
 899 }
 900
 901 #define VERIFY_COMMIT_GRAPH_ERROR_HASH 2
 902 static int verify_commit_graph_error;
 903
 904 static void graph_report(const char *fmt, ...)
 905 {
 906         va_list ap;
 907
 908         verify_commit_graph_error = 1;
 909         va_start(ap, fmt);
 910         vfprintf(stderr, fmt, ap);
 911         fprintf(stderr, "\n");
 912         va_end(ap);
 913 }
 914
 915 #define GENERATION_ZERO_EXISTS 1
 916 #define GENERATION_NUMBER_EXISTS 2
 917
 918 int verify_commit_graph(struct repository *r, struct commit_graph *g)
 919 {
 920         uint32_t i, cur_fanout_pos = 0;
 921         struct object_id prev_oid, cur_oid, checksum;
 922         int generation_zero = 0;
 923         struct hashfile *f;
 924         int devnull;
 925
 926         if (!g) {
 927                 graph_report("no commit-graph file loaded");
 928                 return 1;
 929         }
 930
 931         verify_commit_graph_error = 0;
 932
 933         if (!g->chunk_oid_fanout)
 934                 graph_report("commit-graph is missing the OID Fanout chunk");
 935         if (!g->chunk_oid_lookup)
 936                 graph_report("commit-graph is missing the OID Lookup chunk");
 937         if (!g->chunk_commit_data)
 938                 graph_report("commit-graph is missing the Commit Data chunk");
 939
 940         if (verify_commit_graph_error)
 941                 return verify_commit_graph_error;
 942
 943         devnull = open("/dev/null", O_WRONLY);
 944         f = hashfd(devnull, NULL);
 945         hashwrite(f, g->data, g->data_len - g->hash_len);
 946         finalize_hashfile(f, checksum.hash, CSUM_CLOSE);
 947         if (hashcmp(checksum.hash, g->data + g->data_len - g->hash_len)) {
 948                 graph_report(_("the commit-graph file has incorrect checksum and is likely corrupt"));
 949                 verify_commit_graph_error = VERIFY_COMMIT_GRAPH_ERROR_HASH;
 950         }
 951
 952         for (i = 0; i < g->num_commits; i++) {
 953                 struct commit *graph_commit;
 954
 955                 hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
 956
 957                 if (i && oidcmp(&prev_oid, &cur_oid) >= 0)
 958                         graph_report("commit-graph has incorrect OID order: %s then %s",
 959                                      oid_to_hex(&prev_oid),
 960                                      oid_to_hex(&cur_oid));
 961
 962                 oidcpy(&prev_oid, &cur_oid);
 963
 964                 while (cur_oid.hash[0] > cur_fanout_pos) {
 965                         uint32_t fanout_value = get_be32(g->chunk_oid_fanout + cur_fanout_pos);
 966
 967                         if (i != fanout_value)
 968                                 graph_report("commit-graph has incorrect fanout value: fanout[%d] = %u != %u",
 969                                              cur_fanout_pos, fanout_value, i);
 970                         cur_fanout_pos++;
 971                 }
 972
 973                 graph_commit = lookup_commit(r, &cur_oid);
 974                 if (!parse_commit_in_graph_one(g, graph_commit))
 975                         graph_report("failed to parse %s from commit-graph",
 976                                      oid_to_hex(&cur_oid));
 977         }
 978
 979         while (cur_fanout_pos < 256) {
 980                 uint32_t fanout_value = get_be32(g->chunk_oid_fanout + cur_fanout_pos);
 981
 982                 if (g->num_commits != fanout_value)
 983                         graph_report("commit-graph has incorrect fanout value: fanout[%d] = %u != %u",
 984                                      cur_fanout_pos, fanout_value, i);
 985
 986                 cur_fanout_pos++;
 987         }
 988
 989         if (verify_commit_graph_error & ~VERIFY_COMMIT_GRAPH_ERROR_HASH)
 990                 return verify_commit_graph_error;
 991
 992         for (i = 0; i < g->num_commits; i++) {
 993                 struct commit *graph_commit, *odb_commit;
 994                 struct commit_list *graph_parents, *odb_parents;
 995                 uint32_t max_generation = 0;
 996
 997                 hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
 998
 999                 graph_commit = lookup_commit(r, &cur_oid);
1000                 odb_commit = (struct commit *)create_object(r, cur_oid.hash, alloc_commit_node(r));
1001                 if (parse_commit_internal(odb_commit, 0, 0)) {
1002                         graph_report("failed to parse %s from object database",
1003                                      oid_to_hex(&cur_oid));
1004                         continue;
1005                 }
1006
1007                 if (oidcmp(&get_commit_tree_in_graph_one(g, graph_commit)->object.oid,
1008                            get_commit_tree_oid(odb_commit)))
1009                         graph_report("root tree OID for commit %s in commit-graph is %s != %s",
1010                                      oid_to_hex(&cur_oid),
1011                                      oid_to_hex(get_commit_tree_oid(graph_commit)),
1012                                      oid_to_hex(get_commit_tree_oid(odb_commit)));
1013
1014                 graph_parents = graph_commit->parents;
1015                 odb_parents = odb_commit->parents;
1016
1017                 while (graph_parents) {
1018                         if (odb_parents == NULL) {
1019                                 graph_report("commit-graph parent list for commit %s is too long",
1020                                              oid_to_hex(&cur_oid));
1021                                 break;
1022                         }
1023
1024                         if (oidcmp(&graph_parents->item->object.oid, &odb_parents->item->object.oid))
1025                                 graph_report("commit-graph parent for %s is %s != %s",
1026                                              oid_to_hex(&cur_oid),
1027                                              oid_to_hex(&graph_parents->item->object.oid),
1028                                              oid_to_hex(&odb_parents->item->object.oid));
1029
1030                         if (graph_parents->item->generation > max_generation)
1031                                 max_generation = graph_parents->item->generation;
1032
1033                         graph_parents = graph_parents->next;
1034                         odb_parents = odb_parents->next;
1035                 }
1036
1037                 if (odb_parents != NULL)
1038                         graph_report("commit-graph parent list for commit %s terminates early",
1039                                      oid_to_hex(&cur_oid));
1040
1041                 if (!graph_commit->generation) {
1042                         if (generation_zero == GENERATION_NUMBER_EXISTS)
1043                                 graph_report("commit-graph has generation number zero for commit %s, but non-zero elsewhere",
1044                                              oid_to_hex(&cur_oid));
1045                         generation_zero = GENERATION_ZERO_EXISTS;
1046                 } else if (generation_zero == GENERATION_ZERO_EXISTS)
1047                         graph_report("commit-graph has non-zero generation number for commit %s, but zero elsewhere",
1048                                      oid_to_hex(&cur_oid));
1049
1050                 if (generation_zero == GENERATION_ZERO_EXISTS)
1051                         continue;
1052
1053                 /*
1054                  * If one of our parents has generation GENERATION_NUMBER_MAX, then
1055                  * our generation is also GENERATION_NUMBER_MAX. Decrement to avoid
1056                  * extra logic in the following condition.
1057                  */
1058                 if (max_generation == GENERATION_NUMBER_MAX)
1059                         max_generation--;
1060
1061                 if (graph_commit->generation != max_generation + 1)
1062                         graph_report("commit-graph generation for commit %s is %u != %u",
1063                                      oid_to_hex(&cur_oid),
1064                                      graph_commit->generation,
1065                                      max_generation + 1);
1066
1067                 if (graph_commit->date != odb_commit->date)
1068                         graph_report("commit date for commit %s in commit-graph is %"PRItime" != %"PRItime,
1069                                      oid_to_hex(&cur_oid),
1070                                      graph_commit->date,
1071                                      odb_commit->date);
1072         }
1073
1074         return verify_commit_graph_error;
1075 }
1076
1077 void free_commit_graph(struct commit_graph *g)
1078 {
1079         if (!g)
1080                 return;
1081         if (g->graph_fd >= 0) {
1082                 munmap((void *)g->data, g->data_len);
1083                 g->data = NULL;
1084                 close(g->graph_fd);
1085         }
1086         free(g);
1087 }