pack-bitmap-write.c

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