pack-bitmap-write.c

   1 #include "cache.h"
   2 #include "object-store.h"
   3 #include "commit.h"
   4 #include "tag.h"
   5 #include "diff.h"
   6 #include "revision.h"
   7 #include "list-objects.h"
   8 #include "progress.h"
   9 #include "pack-revindex.h"
  10 #include "pack.h"
  11 #include "pack-bitmap.h"
  12 #include "sha1-lookup.h"
  13 #include "pack-objects.h"
  14
  15 struct bitmapped_commit {
  16         struct commit *commit;
  17         struct ewah_bitmap *bitmap;
  18         struct ewah_bitmap *write_as;
  19         int flags;
  20         int xor_offset;
  21         uint32_t commit_pos;
  22 };
  23
  24 struct bitmap_writer {
  25         struct ewah_bitmap *commits;
  26         struct ewah_bitmap *trees;
  27         struct ewah_bitmap *blobs;
  28         struct ewah_bitmap *tags;
  29
  30         khash_sha1 *bitmaps;
  31         khash_sha1 *reused;
  32         struct packing_data *to_pack;
  33
  34         struct bitmapped_commit *selected;
  35         unsigned int selected_nr, selected_alloc;
  36
  37         struct progress *progress;
  38         int show_progress;
  39         unsigned char pack_checksum[20];
  40 };
  41
  42 static struct bitmap_writer writer;
  43
  44 void bitmap_writer_show_progress(int show)
  45 {
  46         writer.show_progress = show;
  47 }
  48
  49 /**
  50  * Build the initial type index for the packfile
  51  */
  52 void bitmap_writer_build_type_index(struct packing_data *to_pack,
  53                                     struct pack_idx_entry **index,
  54                                     uint32_t index_nr)
  55 {
  56         uint32_t i;
  57
  58         writer.commits = ewah_new();
  59         writer.trees = ewah_new();
  60         writer.blobs = ewah_new();
  61         writer.tags = ewah_new();
  62         ALLOC_ARRAY(to_pack->in_pack_pos, to_pack->nr_objects);
  63
  64         for (i = 0; i < index_nr; ++i) {
  65                 struct object_entry *entry = (struct object_entry *)index[i];
  66                 enum object_type real_type;
  67
  68                 oe_set_in_pack_pos(to_pack, entry, i);
  69
  70                 switch (oe_type(entry)) {
  71                 case OBJ_COMMIT:
  72                 case OBJ_TREE:
  73                 case OBJ_BLOB:
  74                 case OBJ_TAG:
  75                         real_type = oe_type(entry);
  76                         break;
  77
  78                 default:
  79                         real_type = oid_object_info(the_repository,
  80                                                     &entry->idx.oid, NULL);
  81                         break;
  82                 }
  83
  84                 switch (real_type) {
  85                 case OBJ_COMMIT:
  86                         ewah_set(writer.commits, i);
  87                         break;
  88
  89                 case OBJ_TREE:
  90                         ewah_set(writer.trees, i);
  91                         break;
  92
  93                 case OBJ_BLOB:
  94                         ewah_set(writer.blobs, i);
  95                         break;
  96
  97                 case OBJ_TAG:
  98                         ewah_set(writer.tags, i);
  99                         break;
 100
 101                 default:
 102                         die("Missing type information for %s (%d/%d)",
 103                             oid_to_hex(&entry->idx.oid), real_type,
 104                             oe_type(entry));
 105                 }
 106         }
 107 }
 108
 109 /**
 110  * Compute the actual bitmaps
 111  */
 112 static struct object **seen_objects;
 113 static unsigned int seen_objects_nr, seen_objects_alloc;
 114
 115 static inline void push_bitmapped_commit(struct commit *commit, struct ewah_bitmap *reused)
 116 {
 117         if (writer.selected_nr >= writer.selected_alloc) {
 118                 writer.selected_alloc = (writer.selected_alloc + 32) * 2;
 119                 REALLOC_ARRAY(writer.selected, writer.selected_alloc);
 120         }
 121
 122         writer.selected[writer.selected_nr].commit = commit;
 123         writer.selected[writer.selected_nr].bitmap = reused;
 124         writer.selected[writer.selected_nr].flags = 0;
 125
 126         writer.selected_nr++;
 127 }
 128
 129 static inline void mark_as_seen(struct object *object)
 130 {
 131         ALLOC_GROW(seen_objects, seen_objects_nr + 1, seen_objects_alloc);
 132         seen_objects[seen_objects_nr++] = object;
 133 }
 134
 135 static inline void reset_all_seen(void)
 136 {
 137         unsigned int i;
 138         for (i = 0; i < seen_objects_nr; ++i) {
 139                 seen_objects[i]->flags &= ~(SEEN | ADDED | SHOWN);
 140         }
 141         seen_objects_nr = 0;
 142 }
 143
 144 static uint32_t find_object_pos(const unsigned char *sha1)
 145 {
 146         struct object_entry *entry = packlist_find(writer.to_pack, sha1, NULL);
 147
 148         if (!entry) {
 149                 die("Failed to write bitmap index. Packfile doesn't have full closure "
 150                         "(object %s is missing)", sha1_to_hex(sha1));
 151         }
 152
 153         return oe_in_pack_pos(writer.to_pack, entry);
 154 }
 155
 156 static void show_object(struct object *object, const char *name, void *data)
 157 {
 158         struct bitmap *base = data;
 159         bitmap_set(base, find_object_pos(object->oid.hash));
 160         mark_as_seen(object);
 161 }
 162
 163 static void show_commit(struct commit *commit, void *data)
 164 {
 165         mark_as_seen((struct object *)commit);
 166 }
 167
 168 static int
 169 add_to_include_set(struct bitmap *base, struct commit *commit)
 170 {
 171         khiter_t hash_pos;
 172         uint32_t bitmap_pos = find_object_pos(commit->object.oid.hash);
 173
 174         if (bitmap_get(base, bitmap_pos))
 175                 return 0;
 176
 177         hash_pos = kh_get_sha1(writer.bitmaps, commit->object.oid.hash);
 178         if (hash_pos < kh_end(writer.bitmaps)) {
 179                 struct bitmapped_commit *bc = kh_value(writer.bitmaps, hash_pos);
 180                 bitmap_or_ewah(base, bc->bitmap);
 181                 return 0;
 182         }
 183
 184         bitmap_set(base, bitmap_pos);
 185         return 1;
 186 }
 187
 188 static int
 189 should_include(struct commit *commit, void *_data)
 190 {
 191         struct bitmap *base = _data;
 192
 193         if (!add_to_include_set(base, commit)) {
 194                 struct commit_list *parent = commit->parents;
 195
 196                 mark_as_seen((struct object *)commit);
 197
 198                 while (parent) {
 199                         parent->item->object.flags |= SEEN;
 200                         mark_as_seen((struct object *)parent->item);
 201                         parent = parent->next;
 202                 }
 203
 204                 return 0;
 205         }
 206
 207         return 1;
 208 }
 209
 210 static void compute_xor_offsets(void)
 211 {
 212         static const int MAX_XOR_OFFSET_SEARCH = 10;
 213
 214         int i, next = 0;
 215
 216         while (next < writer.selected_nr) {
 217                 struct bitmapped_commit *stored = &writer.selected[next];
 218
 219                 int best_offset = 0;
 220                 struct ewah_bitmap *best_bitmap = stored->bitmap;
 221                 struct ewah_bitmap *test_xor;
 222
 223                 for (i = 1; i <= MAX_XOR_OFFSET_SEARCH; ++i) {
 224                         int curr = next - i;
 225
 226                         if (curr < 0)
 227                                 break;
 228
 229                         test_xor = ewah_pool_new();
 230                         ewah_xor(writer.selected[curr].bitmap, stored->bitmap, test_xor);
 231
 232                         if (test_xor->buffer_size < best_bitmap->buffer_size) {
 233                                 if (best_bitmap != stored->bitmap)
 234                                         ewah_pool_free(best_bitmap);
 235
 236                                 best_bitmap = test_xor;
 237                                 best_offset = i;
 238                         } else {
 239                                 ewah_pool_free(test_xor);
 240                         }
 241                 }
 242
 243                 stored->xor_offset = best_offset;
 244                 stored->write_as = best_bitmap;
 245
 246                 next++;
 247         }
 248 }
 249
 250 void bitmap_writer_build(struct packing_data *to_pack)
 251 {
 252         static const double REUSE_BITMAP_THRESHOLD = 0.2;
 253
 254         int i, reuse_after, need_reset;
 255         struct bitmap *base = bitmap_new();
 256         struct rev_info revs;
 257
 258         writer.bitmaps = kh_init_sha1();
 259         writer.to_pack = to_pack;
 260
 261         if (writer.show_progress)
 262                 writer.progress = start_progress("Building bitmaps", writer.selected_nr);
 263
 264         init_revisions(&revs, NULL);
 265         revs.tag_objects = 1;
 266         revs.tree_objects = 1;
 267         revs.blob_objects = 1;
 268         revs.no_walk = 0;
 269
 270         revs.include_check = should_include;
 271         reset_revision_walk();
 272
 273         reuse_after = writer.selected_nr * REUSE_BITMAP_THRESHOLD;
 274         need_reset = 0;
 275
 276         for (i = writer.selected_nr - 1; i >= 0; --i) {
 277                 struct bitmapped_commit *stored;
 278                 struct object *object;
 279
 280                 khiter_t hash_pos;
 281                 int hash_ret;
 282
 283                 stored = &writer.selected[i];
 284                 object = (struct object *)stored->commit;
 285
 286                 if (stored->bitmap == NULL) {
 287                         if (i < writer.selected_nr - 1 &&
 288                             (need_reset ||
 289                              !in_merge_bases(writer.selected[i + 1].commit,
 290                                              stored->commit))) {
 291                             bitmap_reset(base);
 292                             reset_all_seen();
 293                         }
 294
 295                         add_pending_object(&revs, object, "");
 296                         revs.include_check_data = base;
 297
 298                         if (prepare_revision_walk(&revs))
 299                                 die("revision walk setup failed");
 300
 301                         traverse_commit_list(&revs, show_commit, show_object, base);
 302
 303                         object_array_clear(&revs.pending);
 304
 305                         stored->bitmap = bitmap_to_ewah(base);
 306                         need_reset = 0;
 307                 } else
 308                         need_reset = 1;
 309
 310                 if (i >= reuse_after)
 311                         stored->flags |= BITMAP_FLAG_REUSE;
 312
 313                 hash_pos = kh_put_sha1(writer.bitmaps, object->oid.hash, &hash_ret);
 314                 if (hash_ret == 0)
 315                         die("Duplicate entry when writing index: %s",
 316                             oid_to_hex(&object->oid));
 317
 318                 kh_value(writer.bitmaps, hash_pos) = stored;
 319                 display_progress(writer.progress, writer.selected_nr - i);
 320         }
 321
 322         bitmap_free(base);
 323         stop_progress(&writer.progress);
 324
 325         compute_xor_offsets();
 326 }
 327
 328 /**
 329  * Select the commits that will be bitmapped
 330  */
 331 static inline unsigned int next_commit_index(unsigned int idx)
 332 {
 333         static const unsigned int MIN_COMMITS = 100;
 334         static const unsigned int MAX_COMMITS = 5000;
 335
 336         static const unsigned int MUST_REGION = 100;
 337         static const unsigned int MIN_REGION = 20000;
 338
 339         unsigned int offset, next;
 340
 341         if (idx <= MUST_REGION)
 342                 return 0;
 343
 344         if (idx <= MIN_REGION) {
 345                 offset = idx - MUST_REGION;
 346                 return (offset < MIN_COMMITS) ? offset : MIN_COMMITS;
 347         }
 348
 349         offset = idx - MIN_REGION;
 350         next = (offset < MAX_COMMITS) ? offset : MAX_COMMITS;
 351
 352         return (next > MIN_COMMITS) ? next : MIN_COMMITS;
 353 }
 354
 355 static int date_compare(const void *_a, const void *_b)
 356 {
 357         struct commit *a = *(struct commit **)_a;
 358         struct commit *b = *(struct commit **)_b;
 359         return (long)b->date - (long)a->date;
 360 }
 361
 362 void bitmap_writer_reuse_bitmaps(struct packing_data *to_pack)
 363 {
 364         struct bitmap_index *bitmap_git;
 365         if (!(bitmap_git = prepare_bitmap_git()))
 366                 return;
 367
 368         writer.reused = kh_init_sha1();
 369         rebuild_existing_bitmaps(bitmap_git, to_pack, writer.reused,
 370                                  writer.show_progress);
 371         /*
 372          * NEEDSWORK: rebuild_existing_bitmaps() makes writer.reused reference
 373          * some bitmaps in bitmap_git, so we can't free the latter.
 374          */
 375 }
 376
 377 static struct ewah_bitmap *find_reused_bitmap(const unsigned char *sha1)
 378 {
 379         khiter_t hash_pos;
 380
 381         if (!writer.reused)
 382                 return NULL;
 383
 384         hash_pos = kh_get_sha1(writer.reused, sha1);
 385         if (hash_pos >= kh_end(writer.reused))
 386                 return NULL;
 387
 388         return kh_value(writer.reused, hash_pos);
 389 }
 390
 391 void bitmap_writer_select_commits(struct commit **indexed_commits,
 392                                   unsigned int indexed_commits_nr,
 393                                   int max_bitmaps)
 394 {
 395         unsigned int i = 0, j, next;
 396
 397         QSORT(indexed_commits, indexed_commits_nr, date_compare);
 398
 399         if (writer.show_progress)
 400                 writer.progress = start_progress("Selecting bitmap commits", 0);
 401
 402         if (indexed_commits_nr < 100) {
 403                 for (i = 0; i < indexed_commits_nr; ++i)
 404                         push_bitmapped_commit(indexed_commits[i], NULL);
 405                 return;
 406         }
 407
 408         for (;;) {
 409                 struct ewah_bitmap *reused_bitmap = NULL;
 410                 struct commit *chosen = NULL;
 411
 412                 next = next_commit_index(i);
 413
 414                 if (i + next >= indexed_commits_nr)
 415                         break;
 416
 417                 if (max_bitmaps > 0 && writer.selected_nr >= max_bitmaps) {
 418                         writer.selected_nr = max_bitmaps;
 419                         break;
 420                 }
 421
 422                 if (next == 0) {
 423                         chosen = indexed_commits[i];
 424                         reused_bitmap = find_reused_bitmap(chosen->object.oid.hash);
 425                 } else {
 426                         chosen = indexed_commits[i + next];
 427
 428                         for (j = 0; j <= next; ++j) {
 429                                 struct commit *cm = indexed_commits[i + j];
 430
 431                                 reused_bitmap = find_reused_bitmap(cm->object.oid.hash);
 432                                 if (reused_bitmap || (cm->object.flags & NEEDS_BITMAP) != 0) {
 433                                         chosen = cm;
 434                                         break;
 435                                 }
 436
 437                                 if (cm->parents && cm->parents->next)
 438                                         chosen = cm;
 439                         }
 440                 }
 441
 442                 push_bitmapped_commit(chosen, reused_bitmap);
 443
 444                 i += next + 1;
 445                 display_progress(writer.progress, i);
 446         }
 447
 448         stop_progress(&writer.progress);
 449 }
 450
 451
 452 static int hashwrite_ewah_helper(void *f, const void *buf, size_t len)
 453 {
 454         /* hashwrite will die on error */
 455         hashwrite(f, buf, len);
 456         return len;
 457 }
 458
 459 /**
 460  * Write the bitmap index to disk
 461  */
 462 static inline void dump_bitmap(struct hashfile *f, struct ewah_bitmap *bitmap)
 463 {
 464         if (ewah_serialize_to(bitmap, hashwrite_ewah_helper, f) < 0)
 465                 die("Failed to write bitmap index");
 466 }
 467
 468 static const unsigned char *sha1_access(size_t pos, void *table)
 469 {
 470         struct pack_idx_entry **index = table;
 471         return index[pos]->oid.hash;
 472 }
 473
 474 static void write_selected_commits_v1(struct hashfile *f,
 475                                       struct pack_idx_entry **index,
 476                                       uint32_t index_nr)
 477 {
 478         int i;
 479
 480         for (i = 0; i < writer.selected_nr; ++i) {
 481                 struct bitmapped_commit *stored = &writer.selected[i];
 482
 483                 int commit_pos =
 484                         sha1_pos(stored->commit->object.oid.hash, index, index_nr, sha1_access);
 485
 486                 if (commit_pos < 0)
 487                         BUG("trying to write commit not in index");
 488
 489                 hashwrite_be32(f, commit_pos);
 490                 hashwrite_u8(f, stored->xor_offset);
 491                 hashwrite_u8(f, stored->flags);
 492
 493                 dump_bitmap(f, stored->write_as);
 494         }
 495 }
 496
 497 static void write_hash_cache(struct hashfile *f,
 498                              struct pack_idx_entry **index,
 499                              uint32_t index_nr)
 500 {
 501         uint32_t i;
 502
 503         for (i = 0; i < index_nr; ++i) {
 504                 struct object_entry *entry = (struct object_entry *)index[i];
 505                 uint32_t hash_value = htonl(entry->hash);
 506                 hashwrite(f, &hash_value, sizeof(hash_value));
 507         }
 508 }
 509
 510 void bitmap_writer_set_checksum(unsigned char *sha1)
 511 {
 512         hashcpy(writer.pack_checksum, sha1);
 513 }
 514
 515 void bitmap_writer_finish(struct pack_idx_entry **index,
 516                           uint32_t index_nr,
 517                           const char *filename,
 518                           uint16_t options)
 519 {
 520         static uint16_t default_version = 1;
 521         static uint16_t flags = BITMAP_OPT_FULL_DAG;
 522         struct strbuf tmp_file = STRBUF_INIT;
 523         struct hashfile *f;
 524
 525         struct bitmap_disk_header header;
 526
 527         int fd = odb_mkstemp(&tmp_file, "pack/tmp_bitmap_XXXXXX");
 528
 529         f = hashfd(fd, tmp_file.buf);
 530
 531         memcpy(header.magic, BITMAP_IDX_SIGNATURE, sizeof(BITMAP_IDX_SIGNATURE));
 532         header.version = htons(default_version);
 533         header.options = htons(flags | options);
 534         header.entry_count = htonl(writer.selected_nr);
 535         hashcpy(header.checksum, writer.pack_checksum);
 536
 537         hashwrite(f, &header, sizeof(header));
 538         dump_bitmap(f, writer.commits);
 539         dump_bitmap(f, writer.trees);
 540         dump_bitmap(f, writer.blobs);
 541         dump_bitmap(f, writer.tags);
 542         write_selected_commits_v1(f, index, index_nr);
 543
 544         if (options & BITMAP_OPT_HASH_CACHE)
 545                 write_hash_cache(f, index, index_nr);
 546
 547         finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_FSYNC | CSUM_CLOSE);
 548
 549         if (adjust_shared_perm(tmp_file.buf))
 550                 die_errno("unable to make temporary bitmap file readable");
 551
 552         if (rename(tmp_file.buf, filename))
 553                 die_errno("unable to rename temporary bitmap file to '%s'", filename);
 554
 555         strbuf_release(&tmp_file);
 556 }