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