[PATCH] clean up pack index handling a bit
[git/git.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 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 }
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 int p1_off, p2_off;
251 const unsigned char *p1_base, *p2_base;
252 struct llist_item *p1_hint = NULL, *p2_hint = NULL;
253
254 p1_off = p2_off = 256 * 4 + 4;
255 p1_base = p1->pack->index_data;
256 p2_base = p2->pack->index_data;
257
258 while (p1_off <= p1->pack->index_size - 3 * 20 &&
259 p2_off <= p2->pack->index_size - 3 * 20)
260 {
261 int cmp = hashcmp(p1_base + p1_off, p2_base + p2_off);
262 /* cmp ~ p1 - p2 */
263 if (cmp == 0) {
264 p1_hint = llist_sorted_remove(p1->unique_objects,
265 p1_base + p1_off, p1_hint);
266 p2_hint = llist_sorted_remove(p2->unique_objects,
267 p1_base + p1_off, p2_hint);
268 p1_off+=24;
269 p2_off+=24;
270 continue;
271 }
272 if (cmp < 0) { /* p1 has the object, p2 doesn't */
273 p1_off+=24;
274 } else { /* p2 has the object, p1 doesn't */
275 p2_off+=24;
276 }
277 }
278 }
279
280 static void pll_free(struct pll *l)
281 {
282 struct pll *old;
283 struct pack_list *opl;
284
285 while (l) {
286 old = l;
287 while (l->pl) {
288 opl = l->pl;
289 l->pl = opl->next;
290 free(opl);
291 }
292 l = l->next;
293 free(old);
294 }
295 }
296
297 /* all the permutations have to be free()d at the same time,
298 * since they refer to each other
299 */
300 static struct pll * get_permutations(struct pack_list *list, int n)
301 {
302 struct pll *subset, *ret = NULL, *new_pll = NULL, *pll;
303
304 if (list == NULL || pack_list_size(list) < n || n == 0)
305 return NULL;
306
307 if (n == 1) {
308 while (list) {
309 new_pll = xmalloc(sizeof(pll));
310 new_pll->pl = NULL;
311 pack_list_insert(&new_pll->pl, list);
312 new_pll->next = ret;
313 ret = new_pll;
314 list = list->next;
315 }
316 return ret;
317 }
318
319 while (list->next) {
320 subset = get_permutations(list->next, n - 1);
321 while (subset) {
322 new_pll = xmalloc(sizeof(pll));
323 new_pll->pl = subset->pl;
324 pack_list_insert(&new_pll->pl, list);
325 new_pll->next = ret;
326 ret = new_pll;
327 subset = subset->next;
328 }
329 list = list->next;
330 }
331 return ret;
332 }
333
334 static int is_superset(struct pack_list *pl, struct llist *list)
335 {
336 struct llist *diff;
337
338 diff = llist_copy(list);
339
340 while (pl) {
341 llist_sorted_difference_inplace(diff, pl->all_objects);
342 if (diff->size == 0) { /* we're done */
343 llist_free(diff);
344 return 1;
345 }
346 pl = pl->next;
347 }
348 llist_free(diff);
349 return 0;
350 }
351
352 static size_t sizeof_union(struct packed_git *p1, struct packed_git *p2)
353 {
354 size_t ret = 0;
355 int p1_off, p2_off;
356 const unsigned char *p1_base, *p2_base;
357
358 p1_off = p2_off = 256 * 4 + 4;
359 p1_base = p1->index_data;
360 p2_base = p2->index_data;
361
362 while (p1_off <= p1->index_size - 3 * 20 &&
363 p2_off <= p2->index_size - 3 * 20)
364 {
365 int cmp = hashcmp(p1_base + p1_off, p2_base + p2_off);
366 /* cmp ~ p1 - p2 */
367 if (cmp == 0) {
368 ret++;
369 p1_off+=24;
370 p2_off+=24;
371 continue;
372 }
373 if (cmp < 0) { /* p1 has the object, p2 doesn't */
374 p1_off+=24;
375 } else { /* p2 has the object, p1 doesn't */
376 p2_off+=24;
377 }
378 }
379 return ret;
380 }
381
382 /* another O(n^2) function ... */
383 static size_t get_pack_redundancy(struct pack_list *pl)
384 {
385 struct pack_list *subset;
386 size_t ret = 0;
387
388 if (pl == NULL)
389 return 0;
390
391 while ((subset = pl->next)) {
392 while(subset) {
393 ret += sizeof_union(pl->pack, subset->pack);
394 subset = subset->next;
395 }
396 pl = pl->next;
397 }
398 return ret;
399 }
400
401 static inline off_t pack_set_bytecount(struct pack_list *pl)
402 {
403 off_t ret = 0;
404 while (pl) {
405 ret += pl->pack->pack_size;
406 ret += pl->pack->index_size;
407 pl = pl->next;
408 }
409 return ret;
410 }
411
412 static void minimize(struct pack_list **min)
413 {
414 struct pack_list *pl, *unique = NULL,
415 *non_unique = NULL, *min_perm = NULL;
416 struct pll *perm, *perm_all, *perm_ok = NULL, *new_perm;
417 struct llist *missing;
418 off_t min_perm_size = 0, perm_size;
419 int n;
420
421 pl = local_packs;
422 while (pl) {
423 if(pl->unique_objects->size)
424 pack_list_insert(&unique, pl);
425 else
426 pack_list_insert(&non_unique, pl);
427 pl = pl->next;
428 }
429 /* find out which objects are missing from the set of unique packs */
430 missing = llist_copy(all_objects);
431 pl = unique;
432 while (pl) {
433 llist_sorted_difference_inplace(missing, pl->all_objects);
434 pl = pl->next;
435 }
436
437 /* return if there are no objects missing from the unique set */
438 if (missing->size == 0) {
439 *min = unique;
440 return;
441 }
442
443 /* find the permutations which contain all missing objects */
444 for (n = 1; n <= pack_list_size(non_unique) && !perm_ok; n++) {
445 perm_all = perm = get_permutations(non_unique, n);
446 while (perm) {
447 if (is_superset(perm->pl, missing)) {
448 new_perm = xmalloc(sizeof(struct pll));
449 memcpy(new_perm, perm, sizeof(struct pll));
450 new_perm->next = perm_ok;
451 perm_ok = new_perm;
452 }
453 perm = perm->next;
454 }
455 if (perm_ok)
456 break;
457 pll_free(perm_all);
458 }
459 if (perm_ok == NULL)
460 die("Internal error: No complete sets found!\n");
461
462 /* find the permutation with the smallest size */
463 perm = perm_ok;
464 while (perm) {
465 perm_size = pack_set_bytecount(perm->pl);
466 if (!min_perm_size || min_perm_size > perm_size) {
467 min_perm_size = perm_size;
468 min_perm = perm->pl;
469 }
470 perm = perm->next;
471 }
472 *min = min_perm;
473 /* add the unique packs to the list */
474 pl = unique;
475 while(pl) {
476 pack_list_insert(min, pl);
477 pl = pl->next;
478 }
479 }
480
481 static void load_all_objects(void)
482 {
483 struct pack_list *pl = local_packs;
484 struct llist_item *hint, *l;
485
486 llist_init(&all_objects);
487
488 while (pl) {
489 hint = NULL;
490 l = pl->all_objects->front;
491 while (l) {
492 hint = llist_insert_sorted_unique(all_objects,
493 l->sha1, hint);
494 l = l->next;
495 }
496 pl = pl->next;
497 }
498 /* remove objects present in remote packs */
499 pl = altodb_packs;
500 while (pl) {
501 llist_sorted_difference_inplace(all_objects, pl->all_objects);
502 pl = pl->next;
503 }
504 }
505
506 /* this scales like O(n^2) */
507 static void cmp_local_packs(void)
508 {
509 struct pack_list *subset, *pl = local_packs;
510
511 while ((subset = pl)) {
512 while((subset = subset->next))
513 cmp_two_packs(pl, subset);
514 pl = pl->next;
515 }
516 }
517
518 static void scan_alt_odb_packs(void)
519 {
520 struct pack_list *local, *alt;
521
522 alt = altodb_packs;
523 while (alt) {
524 local = local_packs;
525 while (local) {
526 llist_sorted_difference_inplace(local->unique_objects,
527 alt->all_objects);
528 local = local->next;
529 }
530 llist_sorted_difference_inplace(all_objects, alt->all_objects);
531 alt = alt->next;
532 }
533 }
534
535 static struct pack_list * add_pack(struct packed_git *p)
536 {
537 struct pack_list l;
538 size_t off;
539 const unsigned char *base;
540
541 if (!p->pack_local && !(alt_odb || verbose))
542 return NULL;
543
544 l.pack = p;
545 llist_init(&l.all_objects);
546
547 off = 256 * 4 + 4;
548 base = p->index_data;
549 while (off <= p->index_size - 3 * 20) {
550 llist_insert_back(l.all_objects, base + off);
551 off += 24;
552 }
553 /* this list will be pruned in cmp_two_packs later */
554 l.unique_objects = llist_copy(l.all_objects);
555 if (p->pack_local)
556 return pack_list_insert(&local_packs, &l);
557 else
558 return pack_list_insert(&altodb_packs, &l);
559 }
560
561 static struct pack_list * add_pack_file(char *filename)
562 {
563 struct packed_git *p = packed_git;
564
565 if (strlen(filename) < 40)
566 die("Bad pack filename: %s\n", filename);
567
568 while (p) {
569 if (strstr(p->pack_name, filename))
570 return add_pack(p);
571 p = p->next;
572 }
573 die("Filename %s not found in packed_git\n", filename);
574 }
575
576 static void load_all(void)
577 {
578 struct packed_git *p = packed_git;
579
580 while (p) {
581 add_pack(p);
582 p = p->next;
583 }
584 }
585
586 int main(int argc, char **argv)
587 {
588 int i;
589 struct pack_list *min, *red, *pl;
590 struct llist *ignore;
591 unsigned char *sha1;
592 char buf[42]; /* 40 byte sha1 + \n + \0 */
593
594 setup_git_directory();
595
596 for (i = 1; i < argc; i++) {
597 const char *arg = argv[i];
598 if(!strcmp(arg, "--")) {
599 i++;
600 break;
601 }
602 if(!strcmp(arg, "--all")) {
603 load_all_packs = 1;
604 continue;
605 }
606 if(!strcmp(arg, "--verbose")) {
607 verbose = 1;
608 continue;
609 }
610 if(!strcmp(arg, "--alt-odb")) {
611 alt_odb = 1;
612 continue;
613 }
614 if(*arg == '-')
615 usage(pack_redundant_usage);
616 else
617 break;
618 }
619
620 prepare_packed_git();
621
622 if (load_all_packs)
623 load_all();
624 else
625 while (*(argv + i) != NULL)
626 add_pack_file(*(argv + i++));
627
628 if (local_packs == NULL)
629 die("Zero packs found!\n");
630
631 load_all_objects();
632
633 cmp_local_packs();
634 if (alt_odb)
635 scan_alt_odb_packs();
636
637 /* ignore objects given on stdin */
638 llist_init(&ignore);
639 if (!isatty(0)) {
640 while (fgets(buf, sizeof(buf), stdin)) {
641 sha1 = xmalloc(20);
642 if (get_sha1_hex(buf, sha1))
643 die("Bad sha1 on stdin: %s", buf);
644 llist_insert_sorted_unique(ignore, sha1, NULL);
645 }
646 }
647 llist_sorted_difference_inplace(all_objects, ignore);
648 pl = local_packs;
649 while (pl) {
650 llist_sorted_difference_inplace(pl->unique_objects, ignore);
651 pl = pl->next;
652 }
653
654 minimize(&min);
655
656 if (verbose) {
657 fprintf(stderr, "There are %lu packs available in alt-odbs.\n",
658 (unsigned long)pack_list_size(altodb_packs));
659 fprintf(stderr, "The smallest (bytewise) set of packs is:\n");
660 pl = min;
661 while (pl) {
662 fprintf(stderr, "\t%s\n", pl->pack->pack_name);
663 pl = pl->next;
664 }
665 fprintf(stderr, "containing %lu duplicate objects "
666 "with a total size of %lukb.\n",
667 (unsigned long)get_pack_redundancy(min),
668 (unsigned long)pack_set_bytecount(min)/1024);
669 fprintf(stderr, "A total of %lu unique objects were considered.\n",
670 (unsigned long)all_objects->size);
671 fprintf(stderr, "Redundant packs (with indexes):\n");
672 }
673 pl = red = pack_list_difference(local_packs, min);
674 while (pl) {
675 printf("%s\n%s\n",
676 sha1_pack_index_name(pl->pack->sha1),
677 pl->pack->pack_name);
678 pl = pl->next;
679 }
680 if (verbose)
681 fprintf(stderr, "%luMB of redundant packs in total.\n",
682 (unsigned long)pack_set_bytecount(red)/(1024*1024));
683
684 return 0;
685 }