Merge branch 'mr/doc-negative-pathspec'
[git] / 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;
52         if ( free_nodes ) {
53                 new = free_nodes;
54                 free_nodes = free_nodes->next;
55         } else {
56                 int i = 1;
57                 ALLOC_ARRAY(new, BLKSIZE);
58                 for (; i < BLKSIZE; i++)
59                         llist_item_put(&new[i]);
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                                                const 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,
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 }