object-store: free alt_odb_list
[git/git.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 }