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