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