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