git-fetch: Reset shallow_depth before auto-following tags.
[git] / 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 #define BLKSIZE 512
12
13 static const char pack_redundant_usage[] =
14 "git-pack-redundant [ --verbose ] [ --alt-odb ] < --all | <.pack filename> ...>";
15
16 static int load_all_packs, verbose, alt_odb;
17
18 struct llist_item {
19         struct llist_item *next;
20         unsigned char *sha1;
21 };
22 static struct llist {
23         struct llist_item *front;
24         struct llist_item *back;
25         size_t size;
26 } *all_objects; /* all objects which must be present in local packfiles */
27
28 static struct pack_list {
29         struct pack_list *next;
30         struct packed_git *pack;
31         struct llist *unique_objects;
32         struct llist *all_objects;
33 } *local_packs = NULL, *altodb_packs = NULL;
34
35 struct pll {
36         struct pll *next;
37         struct pack_list *pl;
38 };
39
40 static struct llist_item *free_nodes;
41
42 static inline void llist_item_put(struct llist_item *item)
43 {
44         item->next = free_nodes;
45         free_nodes = item;
46 }
47
48 static inline struct llist_item *llist_item_get(void)
49 {
50         struct llist_item *new;
51         if ( free_nodes ) {
52                 new = free_nodes;
53                 free_nodes = free_nodes->next;
54         } else {
55                 int i = 1;
56                 new = xmalloc(sizeof(struct llist_item) * BLKSIZE);
57                 for(;i < BLKSIZE; i++) {
58                         llist_item_put(&new[i]);
59                 }
60         }
61         return new;
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, *old, *prev;
84         
85         llist_init(&ret);
86
87         if ((ret->size = list->size) == 0)
88                 return ret;
89
90         new = ret->front = llist_item_get();
91         new->sha1 = list->front->sha1;
92
93         old = list->front->next;
94         while (old) {
95                 prev = new;
96                 new = llist_item_get();
97                 prev->next = new;
98                 new->sha1 = old->sha1;
99                 old = old->next;
100         }
101         new->next = NULL;
102         ret->back = new;
103         
104         return ret;
105 }
106
107 static inline struct llist_item * llist_insert(struct llist *list,
108                                                struct llist_item *after,
109                                                unsigned char *sha1)
110 {
111         struct llist_item *new = llist_item_get();
112         new->sha1 = sha1;
113         new->next = NULL;
114
115         if (after != NULL) {
116                 new->next = after->next;
117                 after->next = new;
118                 if (after == list->back)
119                         list->back = new;
120         } else {/* insert in front */
121                 if (list->size == 0)
122                         list->back = new;
123                 else
124                         new->next = list->front;
125                 list->front = new;
126         }
127         list->size++;
128         return new;
129 }
130
131 static inline struct llist_item *llist_insert_back(struct llist *list, unsigned char *sha1)
132 {
133         return llist_insert(list, list->back, sha1);
134 }
135
136 static inline struct llist_item *llist_insert_sorted_unique(struct llist *list, unsigned char *sha1, struct llist_item *hint)
137 {
138         struct llist_item *prev = NULL, *l;
139
140         l = (hint == NULL) ? list->front : hint;
141         while (l) {
142                 int cmp = hashcmp(l->sha1, sha1);
143                 if (cmp > 0) { /* we insert before this entry */
144                         return llist_insert(list, prev, sha1);
145                 }
146                 if(!cmp) { /* already exists */
147                         return l;
148                 }
149                 prev = l;
150                 l = l->next;
151         }
152         /* insert at the end */
153         return llist_insert_back(list, sha1);
154 }
155
156 /* returns a pointer to an item in front of sha1 */
157 static inline struct llist_item * llist_sorted_remove(struct llist *list, const unsigned char *sha1, struct llist_item *hint)
158 {
159         struct llist_item *prev, *l;
160
161 redo_from_start:
162         l = (hint == NULL) ? list->front : hint;
163         prev = NULL;
164         while (l) {
165                 int cmp = hashcmp(l->sha1, sha1);
166                 if (cmp > 0) /* not in list, since sorted */
167                         return prev;
168                 if(!cmp) { /* found */
169                         if (prev == NULL) {
170                                 if (hint != NULL && hint != list->front) {
171                                         /* we don't know the previous element */
172                                         hint = NULL;
173                                         goto redo_from_start;
174                                 }
175                                 list->front = l->next;
176                         } else
177                                 prev->next = l->next;
178                         if (l == list->back)
179                                 list->back = prev;
180                         llist_item_put(l);
181                         list->size--;
182                         return prev;
183                 }
184                 prev = l;
185                 l = l->next;
186         }
187         return prev;
188 }
189
190 /* computes A\B */
191 static void llist_sorted_difference_inplace(struct llist *A,
192                                      struct llist *B)
193 {
194         struct llist_item *hint, *b;
195
196         hint = NULL;
197         b = B->front;
198
199         while (b) {
200                 hint = llist_sorted_remove(A, b->sha1, hint);
201                 b = b->next;
202         }
203 }
204
205 static inline struct pack_list * pack_list_insert(struct pack_list **pl,
206                                            struct pack_list *entry)
207 {
208         struct pack_list *p = xmalloc(sizeof(struct pack_list));
209         memcpy(p, entry, sizeof(struct pack_list));
210         p->next = *pl;
211         *pl = p;
212         return p;
213 }
214
215 static inline size_t pack_list_size(struct pack_list *pl)
216 {
217         size_t ret = 0;
218         while(pl) {
219                 ret++;
220                 pl = pl->next;
221         }
222         return ret;
223 }
224
225 static struct pack_list * pack_list_difference(const struct pack_list *A,
226                                                const struct pack_list *B)
227 {
228         struct pack_list *ret;
229         const struct pack_list *pl;
230
231         if (A == NULL)
232                 return NULL;
233
234         pl = B;
235         while (pl != NULL) {
236                 if (A->pack == pl->pack)
237                         return pack_list_difference(A->next, B);
238                 pl = pl->next;
239         }
240         ret = xmalloc(sizeof(struct pack_list));
241         memcpy(ret, A, sizeof(struct pack_list));
242         ret->next = pack_list_difference(A->next, B);
243         return ret;
244 }
245
246 static void cmp_two_packs(struct pack_list *p1, struct pack_list *p2)
247 {
248         int p1_off, p2_off;
249         unsigned char *p1_base, *p2_base;
250         struct llist_item *p1_hint = NULL, *p2_hint = NULL;
251
252         p1_off = p2_off = 256 * 4 + 4;
253         p1_base = (unsigned char *) p1->pack->index_base;
254         p2_base = (unsigned char *) p2->pack->index_base;
255
256         while (p1_off <= p1->pack->index_size - 3 * 20 &&
257                p2_off <= p2->pack->index_size - 3 * 20)
258         {
259                 int cmp = hashcmp(p1_base + p1_off, p2_base + p2_off);
260                 /* cmp ~ p1 - p2 */
261                 if (cmp == 0) {
262                         p1_hint = llist_sorted_remove(p1->unique_objects,
263                                         p1_base + p1_off, p1_hint);
264                         p2_hint = llist_sorted_remove(p2->unique_objects,
265                                         p1_base + p1_off, p2_hint);
266                         p1_off+=24;
267                         p2_off+=24;
268                         continue;
269                 }
270                 if (cmp < 0) { /* p1 has the object, p2 doesn't */
271                         p1_off+=24;
272                 } else { /* p2 has the object, p1 doesn't */
273                         p2_off+=24;
274                 }
275         }
276 }
277
278 static void pll_free(struct pll *l)
279 {
280         struct pll *old;
281         struct pack_list *opl;
282
283         while (l) {
284                 old = l;
285                 while (l->pl) {
286                         opl = l->pl;
287                         l->pl = opl->next;
288                         free(opl);
289                 }
290                 l = l->next;
291                 free(old);
292         }
293 }
294
295 /* all the permutations have to be free()d at the same time,
296  * since they refer to each other
297  */
298 static struct pll * get_permutations(struct pack_list *list, int n)
299 {
300         struct pll *subset, *ret = NULL, *new_pll = NULL, *pll;
301
302         if (list == NULL || pack_list_size(list) < n || n == 0)
303                 return NULL;
304
305         if (n == 1) {
306                 while (list) {
307                         new_pll = xmalloc(sizeof(pll));
308                         new_pll->pl = NULL;
309                         pack_list_insert(&new_pll->pl, list);
310                         new_pll->next = ret;
311                         ret = new_pll;
312                         list = list->next;
313                 }
314                 return ret;
315         }
316
317         while (list->next) {
318                 subset = get_permutations(list->next, n - 1);
319                 while (subset) {
320                         new_pll = xmalloc(sizeof(pll));
321                         new_pll->pl = subset->pl;
322                         pack_list_insert(&new_pll->pl, list);
323                         new_pll->next = ret;
324                         ret = new_pll;
325                         subset = subset->next;
326                 }
327                 list = list->next;
328         }
329         return ret;
330 }
331
332 static int is_superset(struct pack_list *pl, struct llist *list)
333 {
334         struct llist *diff;
335
336         diff = llist_copy(list);
337
338         while (pl) {
339                 llist_sorted_difference_inplace(diff, pl->all_objects);
340                 if (diff->size == 0) { /* we're done */
341                         llist_free(diff);
342                         return 1;
343                 }
344                 pl = pl->next;
345         }
346         llist_free(diff);
347         return 0;
348 }
349
350 static size_t sizeof_union(struct packed_git *p1, struct packed_git *p2)
351 {
352         size_t ret = 0;
353         int p1_off, p2_off;
354         unsigned char *p1_base, *p2_base;
355
356         p1_off = p2_off = 256 * 4 + 4;
357         p1_base = (unsigned char *)p1->index_base;
358         p2_base = (unsigned char *)p2->index_base;
359
360         while (p1_off <= p1->index_size - 3 * 20 &&
361                p2_off <= p2->index_size - 3 * 20)
362         {
363                 int cmp = hashcmp(p1_base + p1_off, p2_base + p2_off);
364                 /* cmp ~ p1 - p2 */
365                 if (cmp == 0) {
366                         ret++;
367                         p1_off+=24;
368                         p2_off+=24;
369                         continue;
370                 }
371                 if (cmp < 0) { /* p1 has the object, p2 doesn't */
372                         p1_off+=24;
373                 } else { /* p2 has the object, p1 doesn't */
374                         p2_off+=24;
375                 }
376         }
377         return ret;
378 }
379
380 /* another O(n^2) function ... */
381 static size_t get_pack_redundancy(struct pack_list *pl)
382 {
383         struct pack_list *subset;
384         size_t ret = 0;
385
386         if (pl == NULL)
387                 return 0;
388
389         while ((subset = pl->next)) {
390                 while(subset) {
391                         ret += sizeof_union(pl->pack, subset->pack);
392                         subset = subset->next;
393                 }
394                 pl = pl->next;
395         }
396         return ret;
397 }
398
399 static inline size_t pack_set_bytecount(struct pack_list *pl)
400 {
401         size_t ret = 0;
402         while (pl) {
403                 ret += pl->pack->pack_size;
404                 ret += pl->pack->index_size;
405                 pl = pl->next;
406         }
407         return ret;
408 }
409
410 static void minimize(struct pack_list **min)
411 {
412         struct pack_list *pl, *unique = NULL,
413                 *non_unique = NULL, *min_perm = NULL;
414         struct pll *perm, *perm_all, *perm_ok = NULL, *new_perm;
415         struct llist *missing;
416         size_t min_perm_size = (size_t)-1, perm_size;
417         int n;
418
419         pl = local_packs;
420         while (pl) {
421                 if(pl->unique_objects->size)
422                         pack_list_insert(&unique, pl);
423                 else
424                         pack_list_insert(&non_unique, pl);
425                 pl = pl->next;
426         }
427         /* find out which objects are missing from the set of unique packs */
428         missing = llist_copy(all_objects);
429         pl = unique;
430         while (pl) {
431                 llist_sorted_difference_inplace(missing, pl->all_objects);
432                 pl = pl->next;
433         }
434
435         /* return if there are no objects missing from the unique set */
436         if (missing->size == 0) {
437                 *min = unique;
438                 return;
439         }
440
441         /* find the permutations which contain all missing objects */
442         for (n = 1; n <= pack_list_size(non_unique) && !perm_ok; n++) {
443                 perm_all = perm = get_permutations(non_unique, n);
444                 while (perm) {
445                         if (is_superset(perm->pl, missing)) {
446                                 new_perm = xmalloc(sizeof(struct pll));
447                                 memcpy(new_perm, perm, sizeof(struct pll));
448                                 new_perm->next = perm_ok;
449                                 perm_ok = new_perm;
450                         }
451                         perm = perm->next;
452                 }
453                 if (perm_ok)
454                         break;
455                 pll_free(perm_all);
456         }
457         if (perm_ok == NULL)
458                 die("Internal error: No complete sets found!\n");
459
460         /* find the permutation with the smallest size */
461         perm = perm_ok;
462         while (perm) {
463                 perm_size = pack_set_bytecount(perm->pl);
464                 if (min_perm_size > perm_size) {
465                         min_perm_size = perm_size;
466                         min_perm = perm->pl;
467                 }
468                 perm = perm->next;
469         }
470         *min = min_perm;
471         /* add the unique packs to the list */
472         pl = unique;
473         while(pl) {
474                 pack_list_insert(min, pl);
475                 pl = pl->next;
476         }
477 }
478
479 static void load_all_objects(void)
480 {
481         struct pack_list *pl = local_packs;
482         struct llist_item *hint, *l;
483
484         llist_init(&all_objects);
485
486         while (pl) {
487                 hint = NULL;
488                 l = pl->all_objects->front;
489                 while (l) {
490                         hint = llist_insert_sorted_unique(all_objects,
491                                                           l->sha1, hint);
492                         l = l->next;
493                 }
494                 pl = pl->next;
495         }
496         /* remove objects present in remote packs */
497         pl = altodb_packs;
498         while (pl) {
499                 llist_sorted_difference_inplace(all_objects, pl->all_objects);
500                 pl = pl->next;
501         }
502 }
503
504 /* this scales like O(n^2) */
505 static void cmp_local_packs(void)
506 {
507         struct pack_list *subset, *pl = local_packs;
508
509         while ((subset = pl)) {
510                 while((subset = subset->next))
511                         cmp_two_packs(pl, subset);
512                 pl = pl->next;
513         }
514 }
515
516 static void scan_alt_odb_packs(void)
517 {
518         struct pack_list *local, *alt;
519
520         alt = altodb_packs;
521         while (alt) {
522                 local = local_packs;
523                 while (local) {
524                         llist_sorted_difference_inplace(local->unique_objects,
525                                                         alt->all_objects);
526                         local = local->next;
527                 }
528                 llist_sorted_difference_inplace(all_objects, alt->all_objects);
529                 alt = alt->next;
530         }
531 }
532
533 static struct pack_list * add_pack(struct packed_git *p)
534 {
535         struct pack_list l;
536         size_t off;
537         unsigned char *base;
538
539         if (!p->pack_local && !(alt_odb || verbose))
540                 return NULL;
541
542         l.pack = p;
543         llist_init(&l.all_objects);
544
545         off = 256 * 4 + 4;
546         base = (unsigned char *)p->index_base;
547         while (off <= p->index_size - 3 * 20) {
548                 llist_insert_back(l.all_objects, base + off);
549                 off += 24;
550         }
551         /* this list will be pruned in cmp_two_packs later */
552         l.unique_objects = llist_copy(l.all_objects);
553         if (p->pack_local)
554                 return pack_list_insert(&local_packs, &l);
555         else
556                 return pack_list_insert(&altodb_packs, &l);
557 }
558
559 static struct pack_list * add_pack_file(char *filename)
560 {
561         struct packed_git *p = packed_git;
562
563         if (strlen(filename) < 40)
564                 die("Bad pack filename: %s\n", filename);
565
566         while (p) {
567                 if (strstr(p->pack_name, filename))
568                         return add_pack(p);
569                 p = p->next;
570         }
571         die("Filename %s not found in packed_git\n", filename);
572 }
573
574 static void load_all(void)
575 {
576         struct packed_git *p = packed_git;
577
578         while (p) {
579                 add_pack(p);
580                 p = p->next;
581         }
582 }
583
584 int main(int argc, char **argv)
585 {
586         int i;
587         struct pack_list *min, *red, *pl;
588         struct llist *ignore;
589         unsigned char *sha1;
590         char buf[42]; /* 40 byte sha1 + \n + \0 */
591
592         setup_git_directory();
593
594         for (i = 1; i < argc; i++) {
595                 const char *arg = argv[i];
596                 if(!strcmp(arg, "--")) {
597                         i++;
598                         break;
599                 }
600                 if(!strcmp(arg, "--all")) {
601                         load_all_packs = 1;
602                         continue;
603                 }
604                 if(!strcmp(arg, "--verbose")) {
605                         verbose = 1;
606                         continue;
607                 }
608                 if(!strcmp(arg, "--alt-odb")) {
609                         alt_odb = 1;
610                         continue;
611                 }
612                 if(*arg == '-')
613                         usage(pack_redundant_usage);
614                 else
615                         break;
616         }
617
618         prepare_packed_git();
619
620         if (load_all_packs)
621                 load_all();
622         else
623                 while (*(argv + i) != NULL)
624                         add_pack_file(*(argv + i++));
625
626         if (local_packs == NULL)
627                 die("Zero packs found!\n");
628
629         load_all_objects();
630
631         cmp_local_packs();
632         if (alt_odb)
633                 scan_alt_odb_packs();
634
635         /* ignore objects given on stdin */
636         llist_init(&ignore);
637         if (!isatty(0)) {
638                 while (fgets(buf, sizeof(buf), stdin)) {
639                         sha1 = xmalloc(20);
640                         if (get_sha1_hex(buf, sha1))
641                                 die("Bad sha1 on stdin: %s", buf);
642                         llist_insert_sorted_unique(ignore, sha1, NULL);
643                 }
644         }
645         llist_sorted_difference_inplace(all_objects, ignore);
646         pl = local_packs;
647         while (pl) {
648                 llist_sorted_difference_inplace(pl->unique_objects, ignore);
649                 pl = pl->next;
650         }
651
652         minimize(&min);
653
654         if (verbose) {
655                 fprintf(stderr, "There are %lu packs available in alt-odbs.\n",
656                         (unsigned long)pack_list_size(altodb_packs));
657                 fprintf(stderr, "The smallest (bytewise) set of packs is:\n");
658                 pl = min;
659                 while (pl) {
660                         fprintf(stderr, "\t%s\n", pl->pack->pack_name);
661                         pl = pl->next;
662                 }
663                 fprintf(stderr, "containing %lu duplicate objects "
664                                 "with a total size of %lukb.\n",
665                         (unsigned long)get_pack_redundancy(min),
666                         (unsigned long)pack_set_bytecount(min)/1024);
667                 fprintf(stderr, "A total of %lu unique objects were considered.\n",
668                         (unsigned long)all_objects->size);
669                 fprintf(stderr, "Redundant packs (with indexes):\n");
670         }
671         pl = red = pack_list_difference(local_packs, min);
672         while (pl) {
673                 printf("%s\n%s\n",
674                        sha1_pack_index_name(pl->pack->sha1),
675                        pl->pack->pack_name);
676                 pl = pl->next;
677         }
678         if (verbose)
679                 fprintf(stderr, "%luMB of redundant packs in total.\n",
680                         (unsigned long)pack_set_bytecount(red)/(1024*1024));
681
682         return 0;
683 }