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[git/git.git] / pack-redundant.c
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c283ab21
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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
9bc0f32c 11static const char pack_redundant_usage[] =
1c3039e8 12"git-pack-redundant [ --verbose ] [ --alt-odb ] < --all | <.pack filename> ...>";
c283ab21 13
1c3039e8 14int load_all_packs = 0, verbose = 0, alt_odb = 0;
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15
16struct llist_item {
17 struct llist_item *next;
18 char *sha1;
19};
20struct llist {
21 struct llist_item *front;
22 struct llist_item *back;
23 size_t size;
1c3039e8 24} *all_objects; /* all objects which must be present in local packfiles */
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25
26struct pack_list {
27 struct pack_list *next;
28 struct packed_git *pack;
29 struct llist *unique_objects;
30 struct llist *all_objects;
1c3039e8 31} *local_packs = NULL, *altodb_packs = NULL;
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32
33struct pll {
34 struct pll *next;
35 struct pack_list *pl;
36};
37
38inline void llist_free(struct llist *list)
39{
40 while((list->back = list->front)) {
41 list->front = list->front->next;
42 free(list->back);
43 }
44 free(list);
45}
46
47inline void llist_init(struct llist **list)
48{
49 *list = xmalloc(sizeof(struct llist));
50 (*list)->front = (*list)->back = NULL;
51 (*list)->size = 0;
52}
53
54struct llist * llist_copy(struct llist *list)
55{
56 struct llist *ret;
57 struct llist_item *new, *old, *prev;
58
59 llist_init(&ret);
60
61 if ((ret->size = list->size) == 0)
62 return ret;
63
64 new = ret->front = xmalloc(sizeof(struct llist_item));
65 new->sha1 = list->front->sha1;
66
67 old = list->front->next;
68 while (old) {
69 prev = new;
70 new = xmalloc(sizeof(struct llist_item));
71 prev->next = new;
72 new->sha1 = old->sha1;
73 old = old->next;
74 }
75 new->next = NULL;
76 ret->back = new;
77
78 return ret;
79}
80
81inline struct llist_item * llist_insert(struct llist *list,
82 struct llist_item *after, char *sha1)
83{
84 struct llist_item *new = xmalloc(sizeof(struct llist_item));
85 new->sha1 = sha1;
86 new->next = NULL;
87
88 if (after != NULL) {
89 new->next = after->next;
90 after->next = new;
91 if (after == list->back)
92 list->back = new;
93 } else {/* insert in front */
94 if (list->size == 0)
95 list->back = new;
96 else
97 new->next = list->front;
98 list->front = new;
99 }
100 list->size++;
101 return new;
102}
103
104inline struct llist_item * llist_insert_back(struct llist *list, char *sha1)
105{
106 return llist_insert(list, list->back, sha1);
107}
108
109inline struct llist_item * llist_insert_sorted_unique(struct llist *list,
110 char *sha1, struct llist_item *hint)
111{
112 struct llist_item *prev = NULL, *l;
113
114 l = (hint == NULL) ? list->front : hint;
115 while (l) {
116 int cmp = memcmp(l->sha1, sha1, 20);
117 if (cmp > 0) { /* we insert before this entry */
118 return llist_insert(list, prev, sha1);
119 }
120 if(!cmp) { /* already exists */
121 return l;
122 }
123 prev = l;
124 l = l->next;
125 }
126 /* insert at the end */
127 return llist_insert_back(list, sha1);
128}
129
130/* computes A\B */
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131void llist_sorted_difference_inplace(struct llist *A,
132 struct llist *B)
c283ab21 133{
1c3039e8 134 struct llist_item *prev, *a, *b, *x;
c283ab21 135
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136 prev = a = A->front;
137 b = B->front;
138
139 while (a != NULL && b != NULL) {
140 int cmp = memcmp(a->sha1, b->sha1, 20);
c283ab21 141 if (!cmp) {
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142 x = a;
143 if (a == A->front)
144 A->front = a->next;
145 a = prev->next = a->next;
146
147 if (a == NULL) /* end of list */
148 A->back = prev;
149 A->size--;
150 free(x);
151 b = b->next;
152 } else
153 if (cmp > 0)
154 b = b->next;
155 else {
156 prev = a;
157 a = a->next;
158 }
c283ab21 159 }
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160}
161
162/* returns a pointer to an item in front of sha1 */
163inline struct llist_item * llist_sorted_remove(struct llist *list, char *sha1,
164 struct llist_item *hint)
165{
166 struct llist_item *prev, *l;
167
168redo_from_start:
169 l = (hint == NULL) ? list->front : hint;
170 prev = NULL;
171 while (l) {
172 int cmp = memcmp(l->sha1, sha1, 20);
173 if (cmp > 0) /* not in list, since sorted */
174 return prev;
175 if(!cmp) { /* found */
176 if (prev == NULL) {
177 if (hint != NULL && hint != list->front) {
178 /* we don't know the previous element */
179 hint = NULL;
180 goto redo_from_start;
181 }
182 list->front = l->next;
183 } else
184 prev->next = l->next;
185 if (l == list->back)
186 list->back = prev;
187 free(l);
188 list->size--;
189 return prev;
190 }
191 prev = l;
192 l = l->next;
193 }
194 return prev;
195}
196
197inline struct pack_list * pack_list_insert(struct pack_list **pl,
198 struct pack_list *entry)
199{
200 struct pack_list *p = xmalloc(sizeof(struct pack_list));
201 memcpy(p, entry, sizeof(struct pack_list));
202 p->next = *pl;
203 *pl = p;
204 return p;
205}
206
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207inline size_t pack_list_size(struct pack_list *pl)
208{
209 size_t ret = 0;
210 while(pl) {
211 ret++;
212 pl = pl->next;
213 }
214 return ret;
215}
216
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217struct pack_list * pack_list_difference(struct pack_list *A,
218 struct pack_list *B)
219{
220 struct pack_list *ret, *pl;
221
222 if (A == NULL)
223 return NULL;
224
225 pl = B;
226 while (pl != NULL) {
227 if (A->pack == pl->pack)
228 return pack_list_difference(A->next, B);
229 pl = pl->next;
230 }
231 ret = xmalloc(sizeof(struct pack_list));
232 memcpy(ret, A, sizeof(struct pack_list));
233 ret->next = pack_list_difference(A->next, B);
234 return ret;
235}
236
237void cmp_two_packs(struct pack_list *p1, struct pack_list *p2)
238{
239 int p1_off, p2_off;
240 void *p1_base, *p2_base;
241 struct llist_item *p1_hint = NULL, *p2_hint = NULL;
242
243 p1_off = p2_off = 256 * 4 + 4;
244 p1_base = (void *)p1->pack->index_base;
245 p2_base = (void *)p2->pack->index_base;
246
247 while (p1_off <= p1->pack->index_size - 3 * 20 &&
248 p2_off <= p2->pack->index_size - 3 * 20)
249 {
250 int cmp = memcmp(p1_base + p1_off, p2_base + p2_off, 20);
251 /* cmp ~ p1 - p2 */
252 if (cmp == 0) {
253 p1_hint = llist_sorted_remove(p1->unique_objects,
254 p1_base + p1_off, p1_hint);
255 p2_hint = llist_sorted_remove(p2->unique_objects,
256 p1_base + p1_off, p2_hint);
257 p1_off+=24;
258 p2_off+=24;
259 continue;
260 }
261 if (cmp < 0) { /* p1 has the object, p2 doesn't */
262 p1_off+=24;
263 } else { /* p2 has the object, p1 doesn't */
264 p2_off+=24;
265 }
266 }
267}
268
269/* all the permutations have to be free()d at the same time,
270 * since they refer to each other
271 */
272struct pll * get_all_permutations(struct pack_list *list)
273{
274 struct pll *subset, *pll, *new_pll = NULL; /*silence warning*/
275
276 if (list == NULL)
277 return NULL;
278
279 if (list->next == NULL) {
280 new_pll = xmalloc(sizeof(struct pll));
281 new_pll->next = NULL;
282 new_pll->pl = list;
283 return new_pll;
284 }
285
286 pll = subset = get_all_permutations(list->next);
287 while (pll) {
288 new_pll = xmalloc(sizeof(struct pll));
289 new_pll->next = pll->next;
290 pll->next = new_pll;
291
292 new_pll->pl = xmalloc(sizeof(struct pack_list));
293 memcpy(new_pll->pl, list, sizeof(struct pack_list));
294 new_pll->pl->next = pll->pl;
295
296 pll = new_pll->next;
297 }
298 /* add ourself to the end */
299 new_pll->next = xmalloc(sizeof(struct pll));
300 new_pll->next->pl = xmalloc(sizeof(struct pack_list));
301 new_pll->next->next = NULL;
302 memcpy(new_pll->next->pl, list, sizeof(struct pack_list));
303 new_pll->next->pl->next = NULL;
304
305 return subset;
306}
307
308int is_superset(struct pack_list *pl, struct llist *list)
309{
1c3039e8 310 struct llist *diff;
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311
312 diff = llist_copy(list);
313
314 while (pl) {
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315 llist_sorted_difference_inplace(diff,
316 pl->all_objects);
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317 if (diff->size == 0) { /* we're done */
318 llist_free(diff);
319 return 1;
320 }
321 pl = pl->next;
322 }
323 llist_free(diff);
324 return 0;
325}
326
327size_t sizeof_union(struct packed_git *p1, struct packed_git *p2)
328{
329 size_t ret = 0;
330 int p1_off, p2_off;
331 void *p1_base, *p2_base;
332
333 p1_off = p2_off = 256 * 4 + 4;
334 p1_base = (void *)p1->index_base;
335 p2_base = (void *)p2->index_base;
336
337 while (p1_off <= p1->index_size - 3 * 20 &&
338 p2_off <= p2->index_size - 3 * 20)
339 {
340 int cmp = memcmp(p1_base + p1_off, p2_base + p2_off, 20);
341 /* cmp ~ p1 - p2 */
342 if (cmp == 0) {
343 ret++;
344 p1_off+=24;
345 p2_off+=24;
346 continue;
347 }
348 if (cmp < 0) { /* p1 has the object, p2 doesn't */
349 p1_off+=24;
350 } else { /* p2 has the object, p1 doesn't */
351 p2_off+=24;
352 }
353 }
354 return ret;
355}
356
357/* another O(n^2) function ... */
358size_t get_pack_redundancy(struct pack_list *pl)
359{
360 struct pack_list *subset;
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361
362 if (pl == NULL)
363 return 0;
364
c283ab21
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365 size_t ret = 0;
366 while ((subset = pl->next)) {
367 while(subset) {
368 ret += sizeof_union(pl->pack, subset->pack);
369 subset = subset->next;
370 }
371 pl = pl->next;
372 }
373 return ret;
374}
375
376inline size_t pack_set_bytecount(struct pack_list *pl)
377{
378 size_t ret = 0;
379 while (pl) {
380 ret += pl->pack->pack_size;
381 ret += pl->pack->index_size;
382 pl = pl->next;
383 }
384 return ret;
385}
386
387void minimize(struct pack_list **min)
388{
389 struct pack_list *pl, *unique = NULL,
390 *non_unique = NULL, *min_perm = NULL;
391 struct pll *perm, *perm_all, *perm_ok = NULL, *new_perm;
1c3039e8 392 struct llist *missing;
c283ab21
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393 size_t min_perm_size = (size_t)-1, perm_size;
394
1c3039e8 395 pl = local_packs;
c283ab21
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396 while (pl) {
397 if(pl->unique_objects->size)
398 pack_list_insert(&unique, pl);
399 else
400 pack_list_insert(&non_unique, pl);
401 pl = pl->next;
402 }
403 /* find out which objects are missing from the set of unique packs */
404 missing = llist_copy(all_objects);
405 pl = unique;
406 while (pl) {
1c3039e8
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407 llist_sorted_difference_inplace(missing,
408 pl->all_objects);
c283ab21
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409 pl = pl->next;
410 }
411
1c3039e8 412 /* return if there are no objects missing from the unique set */
c283ab21
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413 if (missing->size == 0) {
414 *min = unique;
415 return;
416 }
417
418 /* find the permutations which contain all missing objects */
419 perm_all = perm = get_all_permutations(non_unique);
420 while (perm) {
421 if (is_superset(perm->pl, missing)) {
422 new_perm = xmalloc(sizeof(struct pll));
423 new_perm->pl = perm->pl;
424 new_perm->next = perm_ok;
425 perm_ok = new_perm;
426 }
427 perm = perm->next;
428 }
429
430 if (perm_ok == NULL)
431 die("Internal error: No complete sets found!\n");
432
433 /* find the permutation with the smallest size */
434 perm = perm_ok;
435 while (perm) {
436 perm_size = pack_set_bytecount(perm->pl);
437 if (min_perm_size > perm_size) {
438 min_perm_size = perm_size;
439 min_perm = perm->pl;
440 }
441 perm = perm->next;
442 }
443 *min = min_perm;
444 /* add the unique packs to the list */
445 pl = unique;
446 while(pl) {
447 pack_list_insert(min, pl);
448 pl = pl->next;
449 }
450}
451
452void load_all_objects()
453{
1c3039e8 454 struct pack_list *pl = local_packs;
c283ab21
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455 struct llist_item *hint, *l;
456 int i;
457
458 llist_init(&all_objects);
459
460 while (pl) {
461 i = 0;
462 hint = NULL;
463 l = pl->all_objects->front;
464 while (l) {
465 hint = llist_insert_sorted_unique(all_objects,
466 l->sha1, hint);
467 l = l->next;
468 }
469 pl = pl->next;
470 }
1c3039e8
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471 /* remove objects present in remote packs */
472 pl = altodb_packs;
473 while (pl) {
474 llist_sorted_difference_inplace(all_objects, pl->all_objects);
475 pl = pl->next;
476 }
c283ab21
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477}
478
479/* this scales like O(n^2) */
480void cmp_packs()
481{
1c3039e8 482 struct pack_list *subset, *pl = local_packs;
c283ab21 483
1c3039e8 484 while ((subset = pl)) {
c283ab21 485 while((subset = subset->next))
1c3039e8
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486 cmp_two_packs(pl, subset);
487 pl = pl->next;
488 }
489
490 pl = altodb_packs;
491 while (pl) {
492 subset = local_packs;
493 while (subset) {
494 llist_sorted_difference_inplace(subset->unique_objects,
495 pl->all_objects);
496 subset = subset->next;
497 }
498 pl = pl->next;
c283ab21
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499 }
500}
501
502struct pack_list * add_pack(struct packed_git *p)
503{
504 struct pack_list l;
505 size_t off;
506 void *base;
507
508 l.pack = p;
509 llist_init(&l.all_objects);
510
511 off = 256 * 4 + 4;
512 base = (void *)p->index_base;
513 while (off <= p->index_size - 3 * 20) {
514 llist_insert_back(l.all_objects, base + off);
515 off+=24;
516 }
517 /* this list will be pruned in cmp_two_packs later */
518 l.unique_objects = llist_copy(l.all_objects);
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519 if (p->pack_local)
520 return pack_list_insert(&local_packs, &l);
521 else
522 return alt_odb ? pack_list_insert(&altodb_packs, &l) : NULL;
c283ab21
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523}
524
525struct pack_list * add_pack_file(char *filename)
526{
527 struct packed_git *p = packed_git;
528
529 if (strlen(filename) < 40)
530 die("Bad pack filename: %s\n", filename);
531
532 while (p) {
533 if (strstr(p->pack_name, filename))
c283ab21
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534 return add_pack(p);
535 p = p->next;
536 }
537 die("Filename %s not found in packed_git\n", filename);
538}
539
540void load_all()
541{
542 struct packed_git *p = packed_git;
543
544 while (p) {
1c3039e8 545 add_pack(p);
c283ab21
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546 p = p->next;
547 }
548}
549
550int main(int argc, char **argv)
551{
552 int i;
553 struct pack_list *min, *red, *pl;
554
555 for (i = 1; i < argc; i++) {
556 const char *arg = argv[i];
9bc0f32c
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557 if(!strcmp(arg, "--")) {
558 i++;
c283ab21 559 break;
9bc0f32c 560 }
1c3039e8
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561 if(!strcmp(arg, "--all")) {
562 load_all_packs = 1;
c283ab21
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563 continue;
564 }
1c3039e8 565 if(!strcmp(arg, "--verbose")) {
c283ab21
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566 verbose = 1;
567 continue;
568 }
1c3039e8
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569 if(!strcmp(arg, "--alt-odb")) {
570 alt_odb = 1;
571 continue;
572 }
c283ab21 573 if(*arg == '-')
9bc0f32c 574 usage(pack_redundant_usage);
c283ab21
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575 else
576 break;
577 }
578
579 prepare_packed_git();
580
1c3039e8 581 if (load_all_packs)
c283ab21
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582 load_all();
583 else
584 while (*(argv + i) != NULL)
585 add_pack_file(*(argv + i++));
586
1c3039e8 587 if (local_packs == NULL)
c283ab21
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588 die("Zero packs found!\n");
589
590 cmp_packs();
591
592 load_all_objects();
593
594 minimize(&min);
595 if (verbose) {
abacbe41
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596 fprintf(stderr, "There are %lu packs available in alt-odbs.\n",
597 (unsigned long)pack_list_size(altodb_packs));
c283ab21
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598 fprintf(stderr, "The smallest (bytewise) set of packs is:\n");
599 pl = min;
600 while (pl) {
601 fprintf(stderr, "\t%s\n", pl->pack->pack_name);
602 pl = pl->next;
603 }
abacbe41
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604 fprintf(stderr, "containing %lu duplicate objects "
605 "with a total size of %lukb.\n",
606 (unsigned long)get_pack_redundancy(min),
607 (unsigned long)pack_set_bytecount(min)/1024);
608 fprintf(stderr, "A total of %lu unique objects were considered.\n",
609 (unsigned long)all_objects->size);
c283ab21
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610 fprintf(stderr, "Redundant packs (with indexes):\n");
611 }
1c3039e8 612 pl = red = pack_list_difference(local_packs, min);
c283ab21
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613 while (pl) {
614 printf("%s\n%s\n",
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615 sha1_pack_index_name(pl->pack->sha1),
616 pl->pack->pack_name);
c283ab21
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617 pl = pl->next;
618 }
619
620 return 0;
621}