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 #include "exec_cmd.h"
  11
  12 #define BLKSIZE 512
  13
  14 static const char pack_redundant_usage[] =
  15 "git pack-redundant [ --verbose ] [ --alt-odb ] < --all | <.pack filename> ...>";
  16
  17 static int load_all_packs, verbose, alt_odb;
  18
  19 struct llist_item {
  20         struct llist_item *next;
  21         const unsigned char *sha1;
  22 };
  23 static struct llist {
  24         struct llist_item *front;
  25         struct llist_item *back;
  26         size_t size;
  27 } *all_objects; /* all objects which must be present in local packfiles */
  28
  29 static struct pack_list {
  30         struct pack_list *next;
  31         struct packed_git *pack;
  32         struct llist *unique_objects;
  33         struct llist *all_objects;
  34 } *local_packs = NULL, *altodb_packs = NULL;
  35
  36 struct pll {
  37         struct pll *next;
  38         struct pack_list *pl;
  39 };
  40
  41 static struct llist_item *free_nodes;
  42
  43 static inline void llist_item_put(struct llist_item *item)
  44 {
  45         item->next = free_nodes;
  46         free_nodes = item;
  47 }
  48
  49 static inline struct llist_item *llist_item_get(void)
  50 {
  51         struct llist_item *new;
  52         if ( free_nodes ) {
  53                 new = free_nodes;
  54                 free_nodes = free_nodes->next;
  55         } else {
  56                 int i = 1;
  57                 new = xmalloc(sizeof(struct llist_item) * BLKSIZE);
  58                 for(;i < BLKSIZE; i++) {
  59                         llist_item_put(&new[i]);
  60                 }
  61         }
  62         return new;
  63 }
  64
  65 static void llist_free(struct llist *list)
  66 {
  67         while((list->back = list->front)) {
  68                 list->front = list->front->next;
  69                 llist_item_put(list->back);
  70         }
  71         free(list);
  72 }
  73
  74 static inline void llist_init(struct llist **list)
  75 {
  76         *list = xmalloc(sizeof(struct llist));
  77         (*list)->front = (*list)->back = NULL;
  78         (*list)->size = 0;
  79 }
  80
  81 static struct llist * llist_copy(struct llist *list)
  82 {
  83         struct llist *ret;
  84         struct llist_item *new, *old, *prev;
  85
  86         llist_init(&ret);
  87
  88         if ((ret->size = list->size) == 0)
  89                 return ret;
  90
  91         new = ret->front = llist_item_get();
  92         new->sha1 = list->front->sha1;
  93
  94         old = list->front->next;
  95         while (old) {
  96                 prev = new;
  97                 new = llist_item_get();
  98                 prev->next = new;
  99                 new->sha1 = old->sha1;
 100                 old = old->next;
 101         }
 102         new->next = NULL;
 103         ret->back = new;
 104
 105         return ret;
 106 }
 107
 108 static inline struct llist_item *llist_insert(struct llist *list,
 109                                               struct llist_item *after,
 110                                                const unsigned char *sha1)
 111 {
 112         struct llist_item *new = llist_item_get();
 113         new->sha1 = sha1;
 114         new->next = NULL;
 115
 116         if (after != NULL) {
 117                 new->next = after->next;
 118                 after->next = new;
 119                 if (after == list->back)
 120                         list->back = new;
 121         } else {/* insert in front */
 122                 if (list->size == 0)
 123                         list->back = new;
 124                 else
 125                         new->next = list->front;
 126                 list->front = new;
 127         }
 128         list->size++;
 129         return new;
 130 }
 131
 132 static inline struct llist_item *llist_insert_back(struct llist *list,
 133                                                    const unsigned char *sha1)
 134 {
 135         return llist_insert(list, list->back, sha1);
 136 }
 137
 138 static inline struct llist_item *llist_insert_sorted_unique(struct llist *list,
 139                         const unsigned char *sha1, struct llist_item *hint)
 140 {
 141         struct llist_item *prev = NULL, *l;
 142
 143         l = (hint == NULL) ? list->front : hint;
 144         while (l) {
 145                 int cmp = hashcmp(l->sha1, sha1);
 146                 if (cmp > 0) { /* we insert before this entry */
 147                         return llist_insert(list, prev, sha1);
 148                 }
 149                 if(!cmp) { /* already exists */
 150                         return l;
 151                 }
 152                 prev = l;
 153                 l = l->next;
 154         }
 155         /* insert at the end */
 156         return llist_insert_back(list, sha1);
 157 }
 158
 159 /* returns a pointer to an item in front of sha1 */
 160 static inline struct llist_item * llist_sorted_remove(struct llist *list, const unsigned char *sha1, struct llist_item *hint)
 161 {
 162         struct llist_item *prev, *l;
 163
 164 redo_from_start:
 165         l = (hint == NULL) ? list->front : hint;
 166         prev = NULL;
 167         while (l) {
 168                 int cmp = hashcmp(l->sha1, sha1);
 169                 if (cmp > 0) /* not in list, since sorted */
 170                         return prev;
 171                 if(!cmp) { /* found */
 172                         if (prev == NULL) {
 173                                 if (hint != NULL && hint != list->front) {
 174                                         /* we don't know the previous element */
 175                                         hint = NULL;
 176                                         goto redo_from_start;
 177                                 }
 178                                 list->front = l->next;
 179                         } else
 180                                 prev->next = l->next;
 181                         if (l == list->back)
 182                                 list->back = prev;
 183                         llist_item_put(l);
 184                         list->size--;
 185                         return prev;
 186                 }
 187                 prev = l;
 188                 l = l->next;
 189         }
 190         return prev;
 191 }
 192
 193 /* computes A\B */
 194 static void llist_sorted_difference_inplace(struct llist *A,
 195                                      struct llist *B)
 196 {
 197         struct llist_item *hint, *b;
 198
 199         hint = NULL;
 200         b = B->front;
 201
 202         while (b) {
 203                 hint = llist_sorted_remove(A, b->sha1, hint);
 204                 b = b->next;
 205         }
 206 }
 207
 208 static inline struct pack_list * pack_list_insert(struct pack_list **pl,
 209                                            struct pack_list *entry)
 210 {
 211         struct pack_list *p = xmalloc(sizeof(struct pack_list));
 212         memcpy(p, entry, sizeof(struct pack_list));
 213         p->next = *pl;
 214         *pl = p;
 215         return p;
 216 }
 217
 218 static inline size_t pack_list_size(struct pack_list *pl)
 219 {
 220         size_t ret = 0;
 221         while(pl) {
 222                 ret++;
 223                 pl = pl->next;
 224         }
 225         return ret;
 226 }
 227
 228 static struct pack_list * pack_list_difference(const struct pack_list *A,
 229                                                const struct pack_list *B)
 230 {
 231         struct pack_list *ret;
 232         const struct pack_list *pl;
 233
 234         if (A == NULL)
 235                 return NULL;
 236
 237         pl = B;
 238         while (pl != NULL) {
 239                 if (A->pack == pl->pack)
 240                         return pack_list_difference(A->next, B);
 241                 pl = pl->next;
 242         }
 243         ret = xmalloc(sizeof(struct pack_list));
 244         memcpy(ret, A, sizeof(struct pack_list));
 245         ret->next = pack_list_difference(A->next, B);
 246         return ret;
 247 }
 248
 249 static void cmp_two_packs(struct pack_list *p1, struct pack_list *p2)
 250 {
 251         unsigned long p1_off = 0, p2_off = 0, p1_step, p2_step;
 252         const unsigned char *p1_base, *p2_base;
 253         struct llist_item *p1_hint = NULL, *p2_hint = NULL;
 254
 255         p1_base = p1->pack->index_data;
 256         p2_base = p2->pack->index_data;
 257         p1_base += 256 * 4 + ((p1->pack->index_version < 2) ? 4 : 8);
 258         p2_base += 256 * 4 + ((p2->pack->index_version < 2) ? 4 : 8);
 259         p1_step = (p1->pack->index_version < 2) ? 24 : 20;
 260         p2_step = (p2->pack->index_version < 2) ? 24 : 20;
 261
 262         while (p1_off < p1->pack->num_objects * p1_step &&
 263                p2_off < p2->pack->num_objects * p2_step)
 264         {
 265                 int cmp = hashcmp(p1_base + p1_off, p2_base + p2_off);
 266                 /* cmp ~ p1 - p2 */
 267                 if (cmp == 0) {
 268                         p1_hint = llist_sorted_remove(p1->unique_objects,
 269                                         p1_base + p1_off, p1_hint);
 270                         p2_hint = llist_sorted_remove(p2->unique_objects,
 271                                         p1_base + p1_off, p2_hint);
 272                         p1_off += p1_step;
 273                         p2_off += p2_step;
 274                         continue;
 275                 }
 276                 if (cmp < 0) { /* p1 has the object, p2 doesn't */
 277                         p1_off += p1_step;
 278                 } else { /* p2 has the object, p1 doesn't */
 279                         p2_off += p2_step;
 280                 }
 281         }
 282 }
 283
 284 static void pll_free(struct pll *l)
 285 {
 286         struct pll *old;
 287         struct pack_list *opl;
 288
 289         while (l) {
 290                 old = l;
 291                 while (l->pl) {
 292                         opl = l->pl;
 293                         l->pl = opl->next;
 294                         free(opl);
 295                 }
 296                 l = l->next;
 297                 free(old);
 298         }
 299 }
 300
 301 /* all the permutations have to be free()d at the same time,
 302  * since they refer to each other
 303  */
 304 static struct pll * get_permutations(struct pack_list *list, int n)
 305 {
 306         struct pll *subset, *ret = NULL, *new_pll = NULL, *pll;
 307
 308         if (list == NULL || pack_list_size(list) < n || n == 0)
 309                 return NULL;
 310
 311         if (n == 1) {
 312                 while (list) {
 313                         new_pll = xmalloc(sizeof(pll));
 314                         new_pll->pl = NULL;
 315                         pack_list_insert(&new_pll->pl, list);
 316                         new_pll->next = ret;
 317                         ret = new_pll;
 318                         list = list->next;
 319                 }
 320                 return ret;
 321         }
 322
 323         while (list->next) {
 324                 subset = get_permutations(list->next, n - 1);
 325                 while (subset) {
 326                         new_pll = xmalloc(sizeof(pll));
 327                         new_pll->pl = subset->pl;
 328                         pack_list_insert(&new_pll->pl, list);
 329                         new_pll->next = ret;
 330                         ret = new_pll;
 331                         subset = subset->next;
 332                 }
 333                 list = list->next;
 334         }
 335         return ret;
 336 }
 337
 338 static int is_superset(struct pack_list *pl, struct llist *list)
 339 {
 340         struct llist *diff;
 341
 342         diff = llist_copy(list);
 343
 344         while (pl) {
 345                 llist_sorted_difference_inplace(diff, pl->all_objects);
 346                 if (diff->size == 0) { /* we're done */
 347                         llist_free(diff);
 348                         return 1;
 349                 }
 350                 pl = pl->next;
 351         }
 352         llist_free(diff);
 353         return 0;
 354 }
 355
 356 static size_t sizeof_union(struct packed_git *p1, struct packed_git *p2)
 357 {
 358         size_t ret = 0;
 359         unsigned long p1_off = 0, p2_off = 0, p1_step, p2_step;
 360         const unsigned char *p1_base, *p2_base;
 361
 362         p1_base = p1->index_data;
 363         p2_base = p2->index_data;
 364         p1_base += 256 * 4 + ((p1->index_version < 2) ? 4 : 8);
 365         p2_base += 256 * 4 + ((p2->index_version < 2) ? 4 : 8);
 366         p1_step = (p1->index_version < 2) ? 24 : 20;
 367         p2_step = (p2->index_version < 2) ? 24 : 20;
 368
 369         while (p1_off < p1->num_objects * p1_step &&
 370                p2_off < p2->num_objects * p2_step)
 371         {
 372                 int cmp = hashcmp(p1_base + p1_off, p2_base + p2_off);
 373                 /* cmp ~ p1 - p2 */
 374                 if (cmp == 0) {
 375                         ret++;
 376                         p1_off += p1_step;
 377                         p2_off += p2_step;
 378                         continue;
 379                 }
 380                 if (cmp < 0) { /* p1 has the object, p2 doesn't */
 381                         p1_off += p1_step;
 382                 } else { /* p2 has the object, p1 doesn't */
 383                         p2_off += p2_step;
 384                 }
 385         }
 386         return ret;
 387 }
 388
 389 /* another O(n^2) function ... */
 390 static size_t get_pack_redundancy(struct pack_list *pl)
 391 {
 392         struct pack_list *subset;
 393         size_t ret = 0;
 394
 395         if (pl == NULL)
 396                 return 0;
 397
 398         while ((subset = pl->next)) {
 399                 while(subset) {
 400                         ret += sizeof_union(pl->pack, subset->pack);
 401                         subset = subset->next;
 402                 }
 403                 pl = pl->next;
 404         }
 405         return ret;
 406 }
 407
 408 static inline off_t pack_set_bytecount(struct pack_list *pl)
 409 {
 410         off_t ret = 0;
 411         while (pl) {
 412                 ret += pl->pack->pack_size;
 413                 ret += pl->pack->index_size;
 414                 pl = pl->next;
 415         }
 416         return ret;
 417 }
 418
 419 static void minimize(struct pack_list **min)
 420 {
 421         struct pack_list *pl, *unique = NULL,
 422                 *non_unique = NULL, *min_perm = NULL;
 423         struct pll *perm, *perm_all, *perm_ok = NULL, *new_perm;
 424         struct llist *missing;
 425         off_t min_perm_size = 0, perm_size;
 426         int n;
 427
 428         pl = local_packs;
 429         while (pl) {
 430                 if(pl->unique_objects->size)
 431                         pack_list_insert(&unique, pl);
 432                 else
 433                         pack_list_insert(&non_unique, pl);
 434                 pl = pl->next;
 435         }
 436         /* find out which objects are missing from the set of unique packs */
 437         missing = llist_copy(all_objects);
 438         pl = unique;
 439         while (pl) {
 440                 llist_sorted_difference_inplace(missing, pl->all_objects);
 441                 pl = pl->next;
 442         }
 443
 444         /* return if there are no objects missing from the unique set */
 445         if (missing->size == 0) {
 446                 *min = unique;
 447                 return;
 448         }
 449
 450         /* find the permutations which contain all missing objects */
 451         for (n = 1; n <= pack_list_size(non_unique) && !perm_ok; n++) {
 452                 perm_all = perm = get_permutations(non_unique, n);
 453                 while (perm) {
 454                         if (is_superset(perm->pl, missing)) {
 455                                 new_perm = xmalloc(sizeof(struct pll));
 456                                 memcpy(new_perm, perm, sizeof(struct pll));
 457                                 new_perm->next = perm_ok;
 458                                 perm_ok = new_perm;
 459                         }
 460                         perm = perm->next;
 461                 }
 462                 if (perm_ok)
 463                         break;
 464                 pll_free(perm_all);
 465         }
 466         if (perm_ok == NULL)
 467                 die("Internal error: No complete sets found!\n");
 468
 469         /* find the permutation with the smallest size */
 470         perm = perm_ok;
 471         while (perm) {
 472                 perm_size = pack_set_bytecount(perm->pl);
 473                 if (!min_perm_size || min_perm_size > perm_size) {
 474                         min_perm_size = perm_size;
 475                         min_perm = perm->pl;
 476                 }
 477                 perm = perm->next;
 478         }
 479         *min = min_perm;
 480         /* add the unique packs to the list */
 481         pl = unique;
 482         while(pl) {
 483                 pack_list_insert(min, pl);
 484                 pl = pl->next;
 485         }
 486 }
 487
 488 static void load_all_objects(void)
 489 {
 490         struct pack_list *pl = local_packs;
 491         struct llist_item *hint, *l;
 492
 493         llist_init(&all_objects);
 494
 495         while (pl) {
 496                 hint = NULL;
 497                 l = pl->all_objects->front;
 498                 while (l) {
 499                         hint = llist_insert_sorted_unique(all_objects,
 500                                                           l->sha1, hint);
 501                         l = l->next;
 502                 }
 503                 pl = pl->next;
 504         }
 505         /* remove objects present in remote packs */
 506         pl = altodb_packs;
 507         while (pl) {
 508                 llist_sorted_difference_inplace(all_objects, pl->all_objects);
 509                 pl = pl->next;
 510         }
 511 }
 512
 513 /* this scales like O(n^2) */
 514 static void cmp_local_packs(void)
 515 {
 516         struct pack_list *subset, *pl = local_packs;
 517
 518         while ((subset = pl)) {
 519                 while((subset = subset->next))
 520                         cmp_two_packs(pl, subset);
 521                 pl = pl->next;
 522         }
 523 }
 524
 525 static void scan_alt_odb_packs(void)
 526 {
 527         struct pack_list *local, *alt;
 528
 529         alt = altodb_packs;
 530         while (alt) {
 531                 local = local_packs;
 532                 while (local) {
 533                         llist_sorted_difference_inplace(local->unique_objects,
 534                                                         alt->all_objects);
 535                         local = local->next;
 536                 }
 537                 llist_sorted_difference_inplace(all_objects, alt->all_objects);
 538                 alt = alt->next;
 539         }
 540 }
 541
 542 static struct pack_list * add_pack(struct packed_git *p)
 543 {
 544         struct pack_list l;
 545         unsigned long off = 0, step;
 546         const unsigned char *base;
 547
 548         if (!p->pack_local && !(alt_odb || verbose))
 549                 return NULL;
 550
 551         l.pack = p;
 552         llist_init(&l.all_objects);
 553
 554         if (open_pack_index(p))
 555                 return NULL;
 556
 557         base = p->index_data;
 558         base += 256 * 4 + ((p->index_version < 2) ? 4 : 8);
 559         step = (p->index_version < 2) ? 24 : 20;
 560         while (off < p->num_objects * step) {
 561                 llist_insert_back(l.all_objects, base + off);
 562                 off += step;
 563         }
 564         /* this list will be pruned in cmp_two_packs later */
 565         l.unique_objects = llist_copy(l.all_objects);
 566         if (p->pack_local)
 567                 return pack_list_insert(&local_packs, &l);
 568         else
 569                 return pack_list_insert(&altodb_packs, &l);
 570 }
 571
 572 static struct pack_list * add_pack_file(char *filename)
 573 {
 574         struct packed_git *p = packed_git;
 575
 576         if (strlen(filename) < 40)
 577                 die("Bad pack filename: %s\n", filename);
 578
 579         while (p) {
 580                 if (strstr(p->pack_name, filename))
 581                         return add_pack(p);
 582                 p = p->next;
 583         }
 584         die("Filename %s not found in packed_git\n", filename);
 585 }
 586
 587 static void load_all(void)
 588 {
 589         struct packed_git *p = packed_git;
 590
 591         while (p) {
 592                 add_pack(p);
 593                 p = p->next;
 594         }
 595 }
 596
 597 int main(int argc, char **argv)
 598 {
 599         int i;
 600         struct pack_list *min, *red, *pl;
 601         struct llist *ignore;
 602         unsigned char *sha1;
 603         char buf[42]; /* 40 byte sha1 + \n + \0 */
 604
 605         if (argv[0] && *argv[0])
 606                 git_extract_argv0_path(argv[0]);
 607
 608         setup_git_directory();
 609
 610         for (i = 1; i < argc; i++) {
 611                 const char *arg = argv[i];
 612                 if(!strcmp(arg, "--")) {
 613                         i++;
 614                         break;
 615                 }
 616                 if(!strcmp(arg, "--all")) {
 617                         load_all_packs = 1;
 618                         continue;
 619                 }
 620                 if(!strcmp(arg, "--verbose")) {
 621                         verbose = 1;
 622                         continue;
 623                 }
 624                 if(!strcmp(arg, "--alt-odb")) {
 625                         alt_odb = 1;
 626                         continue;
 627                 }
 628                 if(*arg == '-')
 629                         usage(pack_redundant_usage);
 630                 else
 631                         break;
 632         }
 633
 634         prepare_packed_git();
 635
 636         if (load_all_packs)
 637                 load_all();
 638         else
 639                 while (*(argv + i) != NULL)
 640                         add_pack_file(*(argv + i++));
 641
 642         if (local_packs == NULL)
 643                 die("Zero packs found!\n");
 644
 645         load_all_objects();
 646
 647         cmp_local_packs();
 648         if (alt_odb)
 649                 scan_alt_odb_packs();
 650
 651         /* ignore objects given on stdin */
 652         llist_init(&ignore);
 653         if (!isatty(0)) {
 654                 while (fgets(buf, sizeof(buf), stdin)) {
 655                         sha1 = xmalloc(20);
 656                         if (get_sha1_hex(buf, sha1))
 657                                 die("Bad sha1 on stdin: %s", buf);
 658                         llist_insert_sorted_unique(ignore, sha1, NULL);
 659                 }
 660         }
 661         llist_sorted_difference_inplace(all_objects, ignore);
 662         pl = local_packs;
 663         while (pl) {
 664                 llist_sorted_difference_inplace(pl->unique_objects, ignore);
 665                 pl = pl->next;
 666         }
 667
 668         minimize(&min);
 669
 670         if (verbose) {
 671                 fprintf(stderr, "There are %lu packs available in alt-odbs.\n",
 672                         (unsigned long)pack_list_size(altodb_packs));
 673                 fprintf(stderr, "The smallest (bytewise) set of packs is:\n");
 674                 pl = min;
 675                 while (pl) {
 676                         fprintf(stderr, "\t%s\n", pl->pack->pack_name);
 677                         pl = pl->next;
 678                 }
 679                 fprintf(stderr, "containing %lu duplicate objects "
 680                                 "with a total size of %lukb.\n",
 681                         (unsigned long)get_pack_redundancy(min),
 682                         (unsigned long)pack_set_bytecount(min)/1024);
 683                 fprintf(stderr, "A total of %lu unique objects were considered.\n",
 684                         (unsigned long)all_objects->size);
 685                 fprintf(stderr, "Redundant packs (with indexes):\n");
 686         }
 687         pl = red = pack_list_difference(local_packs, min);
 688         while (pl) {
 689                 printf("%s\n%s\n",
 690                        sha1_pack_index_name(pl->pack->sha1),
 691                        pl->pack->pack_name);
 692                 pl = pl->next;
 693         }
 694         if (verbose)
 695                 fprintf(stderr, "%luMB of redundant packs in total.\n",
 696                         (unsigned long)pack_set_bytecount(red)/(1024*1024));
 697
 698         return 0;
 699 }