builtin/pack-redundant.c

   1 /*
   2 *
   3 * Copyright 2005, Lukas Sandstrom <lukass@etek.chalmers.se>
   4 *
   5 * This file is licensed under the GPL v2.
   6 *
   7 */
   8
   9 #include "builtin.h"
  10
  11 #define BLKSIZE 512
  12
  13 static const char pack_redundant_usage[] =
  14 "git pack-redundant [--verbose] [--alt-odb] (--all | <filename.pack>...)";
  15
  16 static int load_all_packs, verbose, alt_odb;
  17
  18 struct llist_item {
  19         struct llist_item *next;
  20         const unsigned char *sha1;
  21 };
  22 static struct llist {
  23         struct llist_item *front;
  24         struct llist_item *back;
  25         size_t size;
  26 } *all_objects; /* all objects which must be present in local packfiles */
  27
  28 static struct pack_list {
  29         struct pack_list *next;
  30         struct packed_git *pack;
  31         struct llist *unique_objects;
  32         struct llist *all_objects;
  33 } *local_packs = NULL, *altodb_packs = NULL;
  34
  35 struct pll {
  36         struct pll *next;
  37         struct pack_list *pl;
  38 };
  39
  40 static struct llist_item *free_nodes;
  41
  42 static inline void llist_item_put(struct llist_item *item)
  43 {
  44         item->next = free_nodes;
  45         free_nodes = item;
  46 }
  47
  48 static inline struct llist_item *llist_item_get(void)
  49 {
  50         struct llist_item *new;
  51         if ( free_nodes ) {
  52                 new = free_nodes;
  53                 free_nodes = free_nodes->next;
  54         } else {
  55                 int i = 1;
  56                 new = xmalloc(sizeof(struct llist_item) * BLKSIZE);
  57                 for (; i < BLKSIZE; i++)
  58                         llist_item_put(&new[i]);
  59         }
  60         return new;
  61 }
  62
  63 static void llist_free(struct llist *list)
  64 {
  65         while ((list->back = list->front)) {
  66                 list->front = list->front->next;
  67                 llist_item_put(list->back);
  68         }
  69         free(list);
  70 }
  71
  72 static inline void llist_init(struct llist **list)
  73 {
  74         *list = xmalloc(sizeof(struct llist));
  75         (*list)->front = (*list)->back = NULL;
  76         (*list)->size = 0;
  77 }
  78
  79 static struct llist * llist_copy(struct llist *list)
  80 {
  81         struct llist *ret;
  82         struct llist_item *new, *old, *prev;
  83
  84         llist_init(&ret);
  85
  86         if ((ret->size = list->size) == 0)
  87                 return ret;
  88
  89         new = ret->front = llist_item_get();
  90         new->sha1 = list->front->sha1;
  91
  92         old = list->front->next;
  93         while (old) {
  94                 prev = new;
  95                 new = llist_item_get();
  96                 prev->next = new;
  97                 new->sha1 = old->sha1;
  98                 old = old->next;
  99         }
 100         new->next = NULL;
 101         ret->back = new;
 102
 103         return ret;
 104 }
 105
 106 static inline struct llist_item *llist_insert(struct llist *list,
 107                                               struct llist_item *after,
 108                                                const unsigned char *sha1)
 109 {
 110         struct llist_item *new = llist_item_get();
 111         new->sha1 = sha1;
 112         new->next = NULL;
 113
 114         if (after != NULL) {
 115                 new->next = after->next;
 116                 after->next = new;
 117                 if (after == list->back)
 118                         list->back = new;
 119         } else {/* insert in front */
 120                 if (list->size == 0)
 121                         list->back = new;
 122                 else
 123                         new->next = list->front;
 124                 list->front = new;
 125         }
 126         list->size++;
 127         return new;
 128 }
 129
 130 static inline struct llist_item *llist_insert_back(struct llist *list,
 131                                                    const unsigned char *sha1)
 132 {
 133         return llist_insert(list, list->back, sha1);
 134 }
 135
 136 static inline struct llist_item *llist_insert_sorted_unique(struct llist *list,
 137                         const unsigned char *sha1, struct llist_item *hint)
 138 {
 139         struct llist_item *prev = NULL, *l;
 140
 141         l = (hint == NULL) ? list->front : hint;
 142         while (l) {
 143                 int cmp = hashcmp(l->sha1, sha1);
 144                 if (cmp > 0) { /* we insert before this entry */
 145                         return llist_insert(list, prev, sha1);
 146                 }
 147                 if (!cmp) { /* already exists */
 148                         return l;
 149                 }
 150                 prev = l;
 151                 l = l->next;
 152         }
 153         /* insert at the end */
 154         return llist_insert_back(list, sha1);
 155 }
 156
 157 /* returns a pointer to an item in front of sha1 */
 158 static inline struct llist_item * llist_sorted_remove(struct llist *list, const unsigned char *sha1, struct llist_item *hint)
 159 {
 160         struct llist_item *prev, *l;
 161
 162 redo_from_start:
 163         l = (hint == NULL) ? list->front : hint;
 164         prev = NULL;
 165         while (l) {
 166                 int cmp = hashcmp(l->sha1, sha1);
 167                 if (cmp > 0) /* not in list, since sorted */
 168                         return prev;
 169                 if (!cmp) { /* found */
 170                         if (prev == NULL) {
 171                                 if (hint != NULL && hint != list->front) {
 172                                         /* we don't know the previous element */
 173                                         hint = NULL;
 174                                         goto redo_from_start;
 175                                 }
 176                                 list->front = l->next;
 177                         } else
 178                                 prev->next = l->next;
 179                         if (l == list->back)
 180                                 list->back = prev;
 181                         llist_item_put(l);
 182                         list->size--;
 183                         return prev;
 184                 }
 185                 prev = l;
 186                 l = l->next;
 187         }
 188         return prev;
 189 }
 190
 191 /* computes A\B */
 192 static void llist_sorted_difference_inplace(struct llist *A,
 193                                      struct llist *B)
 194 {
 195         struct llist_item *hint, *b;
 196
 197         hint = NULL;
 198         b = B->front;
 199
 200         while (b) {
 201                 hint = llist_sorted_remove(A, b->sha1, hint);
 202                 b = b->next;
 203         }
 204 }
 205
 206 static inline struct pack_list * pack_list_insert(struct pack_list **pl,
 207                                            struct pack_list *entry)
 208 {
 209         struct pack_list *p = xmalloc(sizeof(struct pack_list));
 210         memcpy(p, entry, sizeof(struct pack_list));
 211         p->next = *pl;
 212         *pl = p;
 213         return p;
 214 }
 215
 216 static inline size_t pack_list_size(struct pack_list *pl)
 217 {
 218         size_t ret = 0;
 219         while (pl) {
 220                 ret++;
 221                 pl = pl->next;
 222         }
 223         return ret;
 224 }
 225
 226 static struct pack_list * pack_list_difference(const struct pack_list *A,
 227                                                const struct pack_list *B)
 228 {
 229         struct pack_list *ret;
 230         const struct pack_list *pl;
 231
 232         if (A == NULL)
 233                 return NULL;
 234
 235         pl = B;
 236         while (pl != NULL) {
 237                 if (A->pack == pl->pack)
 238                         return pack_list_difference(A->next, B);
 239                 pl = pl->next;
 240         }
 241         ret = xmalloc(sizeof(struct pack_list));
 242         memcpy(ret, A, sizeof(struct pack_list));
 243         ret->next = pack_list_difference(A->next, B);
 244         return ret;
 245 }
 246
 247 static void cmp_two_packs(struct pack_list *p1, struct pack_list *p2)
 248 {
 249         unsigned long p1_off = 0, p2_off = 0, p1_step, p2_step;
 250         const unsigned char *p1_base, *p2_base;
 251         struct llist_item *p1_hint = NULL, *p2_hint = NULL;
 252
 253         p1_base = p1->pack->index_data;
 254         p2_base = p2->pack->index_data;
 255         p1_base += 256 * 4 + ((p1->pack->index_version < 2) ? 4 : 8);
 256         p2_base += 256 * 4 + ((p2->pack->index_version < 2) ? 4 : 8);
 257         p1_step = (p1->pack->index_version < 2) ? 24 : 20;
 258         p2_step = (p2->pack->index_version < 2) ? 24 : 20;
 259
 260         while (p1_off < p1->pack->num_objects * p1_step &&
 261                p2_off < p2->pack->num_objects * p2_step)
 262         {
 263                 int cmp = hashcmp(p1_base + p1_off, p2_base + p2_off);
 264                 /* cmp ~ p1 - p2 */
 265                 if (cmp == 0) {
 266                         p1_hint = llist_sorted_remove(p1->unique_objects,
 267                                         p1_base + p1_off, p1_hint);
 268                         p2_hint = llist_sorted_remove(p2->unique_objects,
 269                                         p1_base + p1_off, p2_hint);
 270                         p1_off += p1_step;
 271                         p2_off += p2_step;
 272                         continue;
 273                 }
 274                 if (cmp < 0) { /* p1 has the object, p2 doesn't */
 275                         p1_off += p1_step;
 276                 } else { /* p2 has the object, p1 doesn't */
 277                         p2_off += p2_step;
 278                 }
 279         }
 280 }
 281
 282 static void pll_free(struct pll *l)
 283 {
 284         struct pll *old;
 285         struct pack_list *opl;
 286
 287         while (l) {
 288                 old = l;
 289                 while (l->pl) {
 290                         opl = l->pl;
 291                         l->pl = opl->next;
 292                         free(opl);
 293                 }
 294                 l = l->next;
 295                 free(old);
 296         }
 297 }
 298
 299 /* all the permutations have to be free()d at the same time,
 300  * since they refer to each other
 301  */
 302 static struct pll * get_permutations(struct pack_list *list, int n)
 303 {
 304         struct pll *subset, *ret = NULL, *new_pll = NULL;
 305
 306         if (list == NULL || pack_list_size(list) < n || n == 0)
 307                 return NULL;
 308
 309         if (n == 1) {
 310                 while (list) {
 311                         new_pll = xmalloc(sizeof(*new_pll));
 312                         new_pll->pl = NULL;
 313                         pack_list_insert(&new_pll->pl, list);
 314                         new_pll->next = ret;
 315                         ret = new_pll;
 316                         list = list->next;
 317                 }
 318                 return ret;
 319         }
 320
 321         while (list->next) {
 322                 subset = get_permutations(list->next, n - 1);
 323                 while (subset) {
 324                         new_pll = xmalloc(sizeof(*new_pll));
 325                         new_pll->pl = subset->pl;
 326                         pack_list_insert(&new_pll->pl, list);
 327                         new_pll->next = ret;
 328                         ret = new_pll;
 329                         subset = subset->next;
 330                 }
 331                 list = list->next;
 332         }
 333         return ret;
 334 }
 335
 336 static int is_superset(struct pack_list *pl, struct llist *list)
 337 {
 338         struct llist *diff;
 339
 340         diff = llist_copy(list);
 341
 342         while (pl) {
 343                 llist_sorted_difference_inplace(diff, pl->all_objects);
 344                 if (diff->size == 0) { /* we're done */
 345                         llist_free(diff);
 346                         return 1;
 347                 }
 348                 pl = pl->next;
 349         }
 350         llist_free(diff);
 351         return 0;
 352 }
 353
 354 static size_t sizeof_union(struct packed_git *p1, struct packed_git *p2)
 355 {
 356         size_t ret = 0;
 357         unsigned long p1_off = 0, p2_off = 0, p1_step, p2_step;
 358         const unsigned char *p1_base, *p2_base;
 359
 360         p1_base = p1->index_data;
 361         p2_base = p2->index_data;
 362         p1_base += 256 * 4 + ((p1->index_version < 2) ? 4 : 8);
 363         p2_base += 256 * 4 + ((p2->index_version < 2) ? 4 : 8);
 364         p1_step = (p1->index_version < 2) ? 24 : 20;
 365         p2_step = (p2->index_version < 2) ? 24 : 20;
 366
 367         while (p1_off < p1->num_objects * p1_step &&
 368                p2_off < p2->num_objects * p2_step)
 369         {
 370                 int cmp = hashcmp(p1_base + p1_off, p2_base + p2_off);
 371                 /* cmp ~ p1 - p2 */
 372                 if (cmp == 0) {
 373                         ret++;
 374                         p1_off += p1_step;
 375                         p2_off += p2_step;
 376                         continue;
 377                 }
 378                 if (cmp < 0) { /* p1 has the object, p2 doesn't */
 379                         p1_off += p1_step;
 380                 } else { /* p2 has the object, p1 doesn't */
 381                         p2_off += p2_step;
 382                 }
 383         }
 384         return ret;
 385 }
 386
 387 /* another O(n^2) function ... */
 388 static size_t get_pack_redundancy(struct pack_list *pl)
 389 {
 390         struct pack_list *subset;
 391         size_t ret = 0;
 392
 393         if (pl == NULL)
 394                 return 0;
 395
 396         while ((subset = pl->next)) {
 397                 while (subset) {
 398                         ret += sizeof_union(pl->pack, subset->pack);
 399                         subset = subset->next;
 400                 }
 401                 pl = pl->next;
 402         }
 403         return ret;
 404 }
 405
 406 static inline off_t pack_set_bytecount(struct pack_list *pl)
 407 {
 408         off_t ret = 0;
 409         while (pl) {
 410                 ret += pl->pack->pack_size;
 411                 ret += pl->pack->index_size;
 412                 pl = pl->next;
 413         }
 414         return ret;
 415 }
 416
 417 static void minimize(struct pack_list **min)
 418 {
 419         struct pack_list *pl, *unique = NULL,
 420                 *non_unique = NULL, *min_perm = NULL;
 421         struct pll *perm, *perm_all, *perm_ok = NULL, *new_perm;
 422         struct llist *missing;
 423         off_t min_perm_size = 0, perm_size;
 424         int n;
 425
 426         pl = local_packs;
 427         while (pl) {
 428                 if (pl->unique_objects->size)
 429                         pack_list_insert(&unique, pl);
 430                 else
 431                         pack_list_insert(&non_unique, pl);
 432                 pl = pl->next;
 433         }
 434         /* find out which objects are missing from the set of unique packs */
 435         missing = llist_copy(all_objects);
 436         pl = unique;
 437         while (pl) {
 438                 llist_sorted_difference_inplace(missing, pl->all_objects);
 439                 pl = pl->next;
 440         }
 441
 442         /* return if there are no objects missing from the unique set */
 443         if (missing->size == 0) {
 444                 *min = unique;
 445                 return;
 446         }
 447
 448         /* find the permutations which contain all missing objects */
 449         for (n = 1; n <= pack_list_size(non_unique) && !perm_ok; n++) {
 450                 perm_all = perm = get_permutations(non_unique, n);
 451                 while (perm) {
 452                         if (is_superset(perm->pl, missing)) {
 453                                 new_perm = xmalloc(sizeof(struct pll));
 454                                 memcpy(new_perm, perm, sizeof(struct pll));
 455                                 new_perm->next = perm_ok;
 456                                 perm_ok = new_perm;
 457                         }
 458                         perm = perm->next;
 459                 }
 460                 if (perm_ok)
 461                         break;
 462                 pll_free(perm_all);
 463         }
 464         if (perm_ok == NULL)
 465                 die("Internal error: No complete sets found!");
 466
 467         /* find the permutation with the smallest size */
 468         perm = perm_ok;
 469         while (perm) {
 470                 perm_size = pack_set_bytecount(perm->pl);
 471                 if (!min_perm_size || min_perm_size > perm_size) {
 472                         min_perm_size = perm_size;
 473                         min_perm = perm->pl;
 474                 }
 475                 perm = perm->next;
 476         }
 477         *min = min_perm;
 478         /* add the unique packs to the list */
 479         pl = unique;
 480         while (pl) {
 481                 pack_list_insert(min, pl);
 482                 pl = pl->next;
 483         }
 484 }
 485
 486 static void load_all_objects(void)
 487 {
 488         struct pack_list *pl = local_packs;
 489         struct llist_item *hint, *l;
 490
 491         llist_init(&all_objects);
 492
 493         while (pl) {
 494                 hint = NULL;
 495                 l = pl->all_objects->front;
 496                 while (l) {
 497                         hint = llist_insert_sorted_unique(all_objects,
 498                                                           l->sha1, hint);
 499                         l = l->next;
 500                 }
 501                 pl = pl->next;
 502         }
 503         /* remove objects present in remote packs */
 504         pl = altodb_packs;
 505         while (pl) {
 506                 llist_sorted_difference_inplace(all_objects, pl->all_objects);
 507                 pl = pl->next;
 508         }
 509 }
 510
 511 /* this scales like O(n^2) */
 512 static void cmp_local_packs(void)
 513 {
 514         struct pack_list *subset, *pl = local_packs;
 515
 516         while ((subset = pl)) {
 517                 while ((subset = subset->next))
 518                         cmp_two_packs(pl, subset);
 519                 pl = pl->next;
 520         }
 521 }
 522
 523 static void scan_alt_odb_packs(void)
 524 {
 525         struct pack_list *local, *alt;
 526
 527         alt = altodb_packs;
 528         while (alt) {
 529                 local = local_packs;
 530                 while (local) {
 531                         llist_sorted_difference_inplace(local->unique_objects,
 532                                                         alt->all_objects);
 533                         local = local->next;
 534                 }
 535                 llist_sorted_difference_inplace(all_objects, alt->all_objects);
 536                 alt = alt->next;
 537         }
 538 }
 539
 540 static struct pack_list * add_pack(struct packed_git *p)
 541 {
 542         struct pack_list l;
 543         unsigned long off = 0, step;
 544         const unsigned char *base;
 545
 546         if (!p->pack_local && !(alt_odb || verbose))
 547                 return NULL;
 548
 549         l.pack = p;
 550         llist_init(&l.all_objects);
 551
 552         if (open_pack_index(p))
 553                 return NULL;
 554
 555         base = p->index_data;
 556         base += 256 * 4 + ((p->index_version < 2) ? 4 : 8);
 557         step = (p->index_version < 2) ? 24 : 20;
 558         while (off < p->num_objects * step) {
 559                 llist_insert_back(l.all_objects, base + off);
 560                 off += step;
 561         }
 562         /* this list will be pruned in cmp_two_packs later */
 563         l.unique_objects = llist_copy(l.all_objects);
 564         if (p->pack_local)
 565                 return pack_list_insert(&local_packs, &l);
 566         else
 567                 return pack_list_insert(&altodb_packs, &l);
 568 }
 569
 570 static struct pack_list * add_pack_file(const char *filename)
 571 {
 572         struct packed_git *p = packed_git;
 573
 574         if (strlen(filename) < 40)
 575                 die("Bad pack filename: %s", filename);
 576
 577         while (p) {
 578                 if (strstr(p->pack_name, filename))
 579                         return add_pack(p);
 580                 p = p->next;
 581         }
 582         die("Filename %s not found in packed_git", filename);
 583 }
 584
 585 static void load_all(void)
 586 {
 587         struct packed_git *p = packed_git;
 588
 589         while (p) {
 590                 add_pack(p);
 591                 p = p->next;
 592         }
 593 }
 594
 595 int cmd_pack_redundant(int argc, const char **argv, const char *prefix)
 596 {
 597         int i;
 598         struct pack_list *min, *red, *pl;
 599         struct llist *ignore;
 600         unsigned char *sha1;
 601         char buf[42]; /* 40 byte sha1 + \n + \0 */
 602
 603         if (argc == 2 && !strcmp(argv[1], "-h"))
 604                 usage(pack_redundant_usage);
 605
 606         for (i = 1; i < argc; i++) {
 607                 const char *arg = argv[i];
 608                 if (!strcmp(arg, "--")) {
 609                         i++;
 610                         break;
 611                 }
 612                 if (!strcmp(arg, "--all")) {
 613                         load_all_packs = 1;
 614                         continue;
 615                 }
 616                 if (!strcmp(arg, "--verbose")) {
 617                         verbose = 1;
 618                         continue;
 619                 }
 620                 if (!strcmp(arg, "--alt-odb")) {
 621                         alt_odb = 1;
 622                         continue;
 623                 }
 624                 if (*arg == '-')
 625                         usage(pack_redundant_usage);
 626                 else
 627                         break;
 628         }
 629
 630         prepare_packed_git();
 631
 632         if (load_all_packs)
 633                 load_all();
 634         else
 635                 while (*(argv + i) != NULL)
 636                         add_pack_file(*(argv + i++));
 637
 638         if (local_packs == NULL)
 639                 die("Zero packs found!");
 640
 641         load_all_objects();
 642
 643         cmp_local_packs();
 644         if (alt_odb)
 645                 scan_alt_odb_packs();
 646
 647         /* ignore objects given on stdin */
 648         llist_init(&ignore);
 649         if (!isatty(0)) {
 650                 while (fgets(buf, sizeof(buf), stdin)) {
 651                         sha1 = xmalloc(20);
 652                         if (get_sha1_hex(buf, sha1))
 653                                 die("Bad sha1 on stdin: %s", buf);
 654                         llist_insert_sorted_unique(ignore, sha1, NULL);
 655                 }
 656         }
 657         llist_sorted_difference_inplace(all_objects, ignore);
 658         pl = local_packs;
 659         while (pl) {
 660                 llist_sorted_difference_inplace(pl->unique_objects, ignore);
 661                 pl = pl->next;
 662         }
 663
 664         minimize(&min);
 665
 666         if (verbose) {
 667                 fprintf(stderr, "There are %lu packs available in alt-odbs.\n",
 668                         (unsigned long)pack_list_size(altodb_packs));
 669                 fprintf(stderr, "The smallest (bytewise) set of packs is:\n");
 670                 pl = min;
 671                 while (pl) {
 672                         fprintf(stderr, "\t%s\n", pl->pack->pack_name);
 673                         pl = pl->next;
 674                 }
 675                 fprintf(stderr, "containing %lu duplicate objects "
 676                                 "with a total size of %lukb.\n",
 677                         (unsigned long)get_pack_redundancy(min),
 678                         (unsigned long)pack_set_bytecount(min)/1024);
 679                 fprintf(stderr, "A total of %lu unique objects were considered.\n",
 680                         (unsigned long)all_objects->size);
 681                 fprintf(stderr, "Redundant packs (with indexes):\n");
 682         }
 683         pl = red = pack_list_difference(local_packs, min);
 684         while (pl) {
 685                 printf("%s\n%s\n",
 686                        sha1_pack_index_name(pl->pack->sha1),
 687                        pl->pack->pack_name);
 688                 pl = pl->next;
 689         }
 690         if (verbose)
 691                 fprintf(stderr, "%luMB of redundant packs in total.\n",
 692                         (unsigned long)pack_set_bytecount(red)/(1024*1024));
 693
 694         return 0;
 695 }