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