builtin/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 "builtin.h"
  10 #include "packfile.h"
  11
  12 #define BLKSIZE 512
  13
  14 static const char pack_redundant_usage[] =
  15 "git pack-redundant [--verbose] [--alt-odb] (--all | <filename.pack>...)";
  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_item;
  52         if ( free_nodes ) {
  53                 new_item = free_nodes;
  54                 free_nodes = free_nodes->next;
  55         } else {
  56                 int i = 1;
  57                 ALLOC_ARRAY(new_item, BLKSIZE);
  58                 for (; i < BLKSIZE; i++)
  59                         llist_item_put(&new_item[i]);
  60         }
  61         return new_item;
  62 }
  63
  64 static void llist_free(struct llist *list)
  65 {
  66         while ((list->back = list->front)) {
  67                 list->front = list->front->next;
  68                 llist_item_put(list->back);
  69         }
  70         free(list);
  71 }
  72
  73 static inline void llist_init(struct llist **list)
  74 {
  75         *list = xmalloc(sizeof(struct llist));
  76         (*list)->front = (*list)->back = NULL;
  77         (*list)->size = 0;
  78 }
  79
  80 static struct llist * llist_copy(struct llist *list)
  81 {
  82         struct llist *ret;
  83         struct llist_item *new_item, *old_item, *prev;
  84
  85         llist_init(&ret);
  86
  87         if ((ret->size = list->size) == 0)
  88                 return ret;
  89
  90         new_item = ret->front = llist_item_get();
  91         new_item->sha1 = list->front->sha1;
  92
  93         old_item = list->front->next;
  94         while (old_item) {
  95                 prev = new_item;
  96                 new_item = llist_item_get();
  97                 prev->next = new_item;
  98                 new_item->sha1 = old_item->sha1;
  99                 old_item = old_item->next;
 100         }
 101         new_item->next = NULL;
 102         ret->back = new_item;
 103
 104         return ret;
 105 }
 106
 107 static inline struct llist_item *llist_insert(struct llist *list,
 108                                               struct llist_item *after,
 109                                                const unsigned char *sha1)
 110 {
 111         struct llist_item *new_item = llist_item_get();
 112         new_item->sha1 = sha1;
 113         new_item->next = NULL;
 114
 115         if (after != NULL) {
 116                 new_item->next = after->next;
 117                 after->next = new_item;
 118                 if (after == list->back)
 119                         list->back = new_item;
 120         } else {/* insert in front */
 121                 if (list->size == 0)
 122                         list->back = new_item;
 123                 else
 124                         new_item->next = list->front;
 125                 list->front = new_item;
 126         }
 127         list->size++;
 128         return new_item;
 129 }
 130
 131 static inline struct llist_item *llist_insert_back(struct llist *list,
 132                                                    const unsigned char *sha1)
 133 {
 134         return llist_insert(list, list->back, sha1);
 135 }
 136
 137 static inline struct llist_item *llist_insert_sorted_unique(struct llist *list,
 138                         const unsigned char *sha1, struct llist_item *hint)
 139 {
 140         struct llist_item *prev = NULL, *l;
 141
 142         l = (hint == NULL) ? list->front : hint;
 143         while (l) {
 144                 int cmp = hashcmp(l->sha1, sha1);
 145                 if (cmp > 0) { /* we insert before this entry */
 146                         return llist_insert(list, prev, sha1);
 147                 }
 148                 if (!cmp) { /* already exists */
 149                         return l;
 150                 }
 151                 prev = l;
 152                 l = l->next;
 153         }
 154         /* insert at the end */
 155         return llist_insert_back(list, sha1);
 156 }
 157
 158 /* returns a pointer to an item in front of sha1 */
 159 static inline struct llist_item * llist_sorted_remove(struct llist *list, const unsigned char *sha1, struct llist_item *hint)
 160 {
 161         struct llist_item *prev, *l;
 162
 163 redo_from_start:
 164         l = (hint == NULL) ? list->front : hint;
 165         prev = NULL;
 166         while (l) {
 167                 int cmp = hashcmp(l->sha1, sha1);
 168                 if (cmp > 0) /* not in list, since sorted */
 169                         return prev;
 170                 if (!cmp) { /* found */
 171                         if (prev == NULL) {
 172                                 if (hint != NULL && hint != list->front) {
 173                                         /* we don't know the previous element */
 174                                         hint = NULL;
 175                                         goto redo_from_start;
 176                                 }
 177                                 list->front = l->next;
 178                         } else
 179                                 prev->next = l->next;
 180                         if (l == list->back)
 181                                 list->back = prev;
 182                         llist_item_put(l);
 183                         list->size--;
 184                         return prev;
 185                 }
 186                 prev = l;
 187                 l = l->next;
 188         }
 189         return prev;
 190 }
 191
 192 /* computes A\B */
 193 static void llist_sorted_difference_inplace(struct llist *A,
 194                                      struct llist *B)
 195 {
 196         struct llist_item *hint, *b;
 197
 198         hint = NULL;
 199         b = B->front;
 200
 201         while (b) {
 202                 hint = llist_sorted_remove(A, b->sha1, hint);
 203                 b = b->next;
 204         }
 205 }
 206
 207 static inline struct pack_list * pack_list_insert(struct pack_list **pl,
 208                                            struct pack_list *entry)
 209 {
 210         struct pack_list *p = xmalloc(sizeof(struct pack_list));
 211         memcpy(p, entry, sizeof(struct pack_list));
 212         p->next = *pl;
 213         *pl = p;
 214         return p;
 215 }
 216
 217 static inline size_t pack_list_size(struct pack_list *pl)
 218 {
 219         size_t ret = 0;
 220         while (pl) {
 221                 ret++;
 222                 pl = pl->next;
 223         }
 224         return ret;
 225 }
 226
 227 static struct pack_list * pack_list_difference(const struct pack_list *A,
 228                                                const struct pack_list *B)
 229 {
 230         struct pack_list *ret;
 231         const struct pack_list *pl;
 232
 233         if (A == NULL)
 234                 return NULL;
 235
 236         pl = B;
 237         while (pl != NULL) {
 238                 if (A->pack == pl->pack)
 239                         return pack_list_difference(A->next, B);
 240                 pl = pl->next;
 241         }
 242         ret = xmalloc(sizeof(struct pack_list));
 243         memcpy(ret, A, sizeof(struct pack_list));
 244         ret->next = pack_list_difference(A->next, B);
 245         return ret;
 246 }
 247
 248 static void cmp_two_packs(struct pack_list *p1, struct pack_list *p2)
 249 {
 250         unsigned long p1_off = 0, p2_off = 0, p1_step, p2_step;
 251         const unsigned char *p1_base, *p2_base;
 252         struct llist_item *p1_hint = NULL, *p2_hint = NULL;
 253
 254         p1_base = p1->pack->index_data;
 255         p2_base = p2->pack->index_data;
 256         p1_base += 256 * 4 + ((p1->pack->index_version < 2) ? 4 : 8);
 257         p2_base += 256 * 4 + ((p2->pack->index_version < 2) ? 4 : 8);
 258         p1_step = (p1->pack->index_version < 2) ? 24 : 20;
 259         p2_step = (p2->pack->index_version < 2) ? 24 : 20;
 260
 261         while (p1_off < p1->pack->num_objects * p1_step &&
 262                p2_off < p2->pack->num_objects * p2_step)
 263         {
 264                 int cmp = hashcmp(p1_base + p1_off, p2_base + p2_off);
 265                 /* cmp ~ p1 - p2 */
 266                 if (cmp == 0) {
 267                         p1_hint = llist_sorted_remove(p1->unique_objects,
 268                                         p1_base + p1_off, p1_hint);
 269                         p2_hint = llist_sorted_remove(p2->unique_objects,
 270                                         p1_base + p1_off, p2_hint);
 271                         p1_off += p1_step;
 272                         p2_off += p2_step;
 273                         continue;
 274                 }
 275                 if (cmp < 0) { /* p1 has the object, p2 doesn't */
 276                         p1_off += p1_step;
 277                 } else { /* p2 has the object, p1 doesn't */
 278                         p2_off += p2_step;
 279                 }
 280         }
 281 }
 282
 283 static void pll_free(struct pll *l)
 284 {
 285         struct pll *old;
 286         struct pack_list *opl;
 287
 288         while (l) {
 289                 old = l;
 290                 while (l->pl) {
 291                         opl = l->pl;
 292                         l->pl = opl->next;
 293                         free(opl);
 294                 }
 295                 l = l->next;
 296                 free(old);
 297         }
 298 }
 299
 300 /* all the permutations have to be free()d at the same time,
 301  * since they refer to each other
 302  */
 303 static struct pll * get_permutations(struct pack_list *list, int n)
 304 {
 305         struct pll *subset, *ret = NULL, *new_pll = NULL;
 306
 307         if (list == NULL || pack_list_size(list) < n || n == 0)
 308                 return NULL;
 309
 310         if (n == 1) {
 311                 while (list) {
 312                         new_pll = xmalloc(sizeof(*new_pll));
 313                         new_pll->pl = NULL;
 314                         pack_list_insert(&new_pll->pl, list);
 315                         new_pll->next = ret;
 316                         ret = new_pll;
 317                         list = list->next;
 318                 }
 319                 return ret;
 320         }
 321
 322         while (list->next) {
 323                 subset = get_permutations(list->next, n - 1);
 324                 while (subset) {
 325                         new_pll = xmalloc(sizeof(*new_pll));
 326                         new_pll->pl = subset->pl;
 327                         pack_list_insert(&new_pll->pl, list);
 328                         new_pll->next = ret;
 329                         ret = new_pll;
 330                         subset = subset->next;
 331                 }
 332                 list = list->next;
 333         }
 334         return ret;
 335 }
 336
 337 static int is_superset(struct pack_list *pl, struct llist *list)
 338 {
 339         struct llist *diff;
 340
 341         diff = llist_copy(list);
 342
 343         while (pl) {
 344                 llist_sorted_difference_inplace(diff, pl->all_objects);
 345                 if (diff->size == 0) { /* we're done */
 346                         llist_free(diff);
 347                         return 1;
 348                 }
 349                 pl = pl->next;
 350         }
 351         llist_free(diff);
 352         return 0;
 353 }
 354
 355 static size_t sizeof_union(struct packed_git *p1, struct packed_git *p2)
 356 {
 357         size_t ret = 0;
 358         unsigned long p1_off = 0, p2_off = 0, p1_step, p2_step;
 359         const unsigned char *p1_base, *p2_base;
 360
 361         p1_base = p1->index_data;
 362         p2_base = p2->index_data;
 363         p1_base += 256 * 4 + ((p1->index_version < 2) ? 4 : 8);
 364         p2_base += 256 * 4 + ((p2->index_version < 2) ? 4 : 8);
 365         p1_step = (p1->index_version < 2) ? 24 : 20;
 366         p2_step = (p2->index_version < 2) ? 24 : 20;
 367
 368         while (p1_off < p1->num_objects * p1_step &&
 369                p2_off < p2->num_objects * p2_step)
 370         {
 371                 int cmp = hashcmp(p1_base + p1_off, p2_base + p2_off);
 372                 /* cmp ~ p1 - p2 */
 373                 if (cmp == 0) {
 374                         ret++;
 375                         p1_off += p1_step;
 376                         p2_off += p2_step;
 377                         continue;
 378                 }
 379                 if (cmp < 0) { /* p1 has the object, p2 doesn't */
 380                         p1_off += p1_step;
 381                 } else { /* p2 has the object, p1 doesn't */
 382                         p2_off += p2_step;
 383                 }
 384         }
 385         return ret;
 386 }
 387
 388 /* another O(n^2) function ... */
 389 static size_t get_pack_redundancy(struct pack_list *pl)
 390 {
 391         struct pack_list *subset;
 392         size_t ret = 0;
 393
 394         if (pl == NULL)
 395                 return 0;
 396
 397         while ((subset = pl->next)) {
 398                 while (subset) {
 399                         ret += sizeof_union(pl->pack, subset->pack);
 400                         subset = subset->next;
 401                 }
 402                 pl = pl->next;
 403         }
 404         return ret;
 405 }
 406
 407 static inline off_t pack_set_bytecount(struct pack_list *pl)
 408 {
 409         off_t ret = 0;
 410         while (pl) {
 411                 ret += pl->pack->pack_size;
 412                 ret += pl->pack->index_size;
 413                 pl = pl->next;
 414         }
 415         return ret;
 416 }
 417
 418 static void minimize(struct pack_list **min)
 419 {
 420         struct pack_list *pl, *unique = NULL,
 421                 *non_unique = NULL, *min_perm = NULL;
 422         struct pll *perm, *perm_all, *perm_ok = NULL, *new_perm;
 423         struct llist *missing;
 424         off_t min_perm_size = 0, perm_size;
 425         int n;
 426
 427         pl = local_packs;
 428         while (pl) {
 429                 if (pl->unique_objects->size)
 430                         pack_list_insert(&unique, pl);
 431                 else
 432                         pack_list_insert(&non_unique, pl);
 433                 pl = pl->next;
 434         }
 435         /* find out which objects are missing from the set of unique packs */
 436         missing = llist_copy(all_objects);
 437         pl = unique;
 438         while (pl) {
 439                 llist_sorted_difference_inplace(missing, pl->all_objects);
 440                 pl = pl->next;
 441         }
 442
 443         /* return if there are no objects missing from the unique set */
 444         if (missing->size == 0) {
 445                 *min = unique;
 446                 free(missing);
 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!");
 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(const char *filename)
 573 {
 574         struct packed_git *p = packed_git;
 575
 576         if (strlen(filename) < 40)
 577                 die("Bad pack filename: %s", 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", 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 cmd_pack_redundant(int argc, const char **argv, const char *prefix)
 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 (argc == 2 && !strcmp(argv[1], "-h"))
 606                 usage(pack_redundant_usage);
 607
 608         for (i = 1; i < argc; i++) {
 609                 const char *arg = argv[i];
 610                 if (!strcmp(arg, "--")) {
 611                         i++;
 612                         break;
 613                 }
 614                 if (!strcmp(arg, "--all")) {
 615                         load_all_packs = 1;
 616                         continue;
 617                 }
 618                 if (!strcmp(arg, "--verbose")) {
 619                         verbose = 1;
 620                         continue;
 621                 }
 622                 if (!strcmp(arg, "--alt-odb")) {
 623                         alt_odb = 1;
 624                         continue;
 625                 }
 626                 if (*arg == '-')
 627                         usage(pack_redundant_usage);
 628                 else
 629                         break;
 630         }
 631
 632         prepare_packed_git();
 633
 634         if (load_all_packs)
 635                 load_all();
 636         else
 637                 while (*(argv + i) != NULL)
 638                         add_pack_file(*(argv + i++));
 639
 640         if (local_packs == NULL)
 641                 die("Zero packs found!");
 642
 643         load_all_objects();
 644
 645         cmp_local_packs();
 646         if (alt_odb)
 647                 scan_alt_odb_packs();
 648
 649         /* ignore objects given on stdin */
 650         llist_init(&ignore);
 651         if (!isatty(0)) {
 652                 while (fgets(buf, sizeof(buf), stdin)) {
 653                         sha1 = xmalloc(20);
 654                         if (get_sha1_hex(buf, sha1))
 655                                 die("Bad sha1 on stdin: %s", buf);
 656                         llist_insert_sorted_unique(ignore, sha1, NULL);
 657                 }
 658         }
 659         llist_sorted_difference_inplace(all_objects, ignore);
 660         pl = local_packs;
 661         while (pl) {
 662                 llist_sorted_difference_inplace(pl->unique_objects, ignore);
 663                 pl = pl->next;
 664         }
 665
 666         minimize(&min);
 667
 668         if (verbose) {
 669                 fprintf(stderr, "There are %lu packs available in alt-odbs.\n",
 670                         (unsigned long)pack_list_size(altodb_packs));
 671                 fprintf(stderr, "The smallest (bytewise) set of packs is:\n");
 672                 pl = min;
 673                 while (pl) {
 674                         fprintf(stderr, "\t%s\n", pl->pack->pack_name);
 675                         pl = pl->next;
 676                 }
 677                 fprintf(stderr, "containing %lu duplicate objects "
 678                                 "with a total size of %lukb.\n",
 679                         (unsigned long)get_pack_redundancy(min),
 680                         (unsigned long)pack_set_bytecount(min)/1024);
 681                 fprintf(stderr, "A total of %lu unique objects were considered.\n",
 682                         (unsigned long)all_objects->size);
 683                 fprintf(stderr, "Redundant packs (with indexes):\n");
 684         }
 685         pl = red = pack_list_difference(local_packs, min);
 686         while (pl) {
 687                 printf("%s\n%s\n",
 688                        sha1_pack_index_name(pl->pack->sha1),
 689                        pl->pack->pack_name);
 690                 pl = pl->next;
 691         }
 692         if (verbose)
 693                 fprintf(stderr, "%luMB of redundant packs in total.\n",
 694                         (unsigned long)pack_set_bytecount(red)/(1024*1024));
 695
 696         return 0;
 697 }