Merge branch 'jk/war-on-sprintf' into maint-2.7
[git] / pack-bitmap.c
1 #include "cache.h"
2 #include "commit.h"
3 #include "tag.h"
4 #include "diff.h"
5 #include "revision.h"
6 #include "progress.h"
7 #include "list-objects.h"
8 #include "pack.h"
9 #include "pack-bitmap.h"
10 #include "pack-revindex.h"
11 #include "pack-objects.h"
12
13 /*
14  * An entry on the bitmap index, representing the bitmap for a given
15  * commit.
16  */
17 struct stored_bitmap {
18         unsigned char sha1[20];
19         struct ewah_bitmap *root;
20         struct stored_bitmap *xor;
21         int flags;
22 };
23
24 /*
25  * The currently active bitmap index. By design, repositories only have
26  * a single bitmap index available (the index for the biggest packfile in
27  * the repository), since bitmap indexes need full closure.
28  *
29  * If there is more than one bitmap index available (e.g. because of alternates),
30  * the active bitmap index is the largest one.
31  */
32 static struct bitmap_index {
33         /* Packfile to which this bitmap index belongs to */
34         struct packed_git *pack;
35
36         /* reverse index for the packfile */
37         struct pack_revindex *reverse_index;
38
39         /*
40          * Mark the first `reuse_objects` in the packfile as reused:
41          * they will be sent as-is without using them for repacking
42          * calculations
43          */
44         uint32_t reuse_objects;
45
46         /* mmapped buffer of the whole bitmap index */
47         unsigned char *map;
48         size_t map_size; /* size of the mmaped buffer */
49         size_t map_pos; /* current position when loading the index */
50
51         /*
52          * Type indexes.
53          *
54          * Each bitmap marks which objects in the packfile  are of the given
55          * type. This provides type information when yielding the objects from
56          * the packfile during a walk, which allows for better delta bases.
57          */
58         struct ewah_bitmap *commits;
59         struct ewah_bitmap *trees;
60         struct ewah_bitmap *blobs;
61         struct ewah_bitmap *tags;
62
63         /* Map from SHA1 -> `stored_bitmap` for all the bitmapped commits */
64         khash_sha1 *bitmaps;
65
66         /* Number of bitmapped commits */
67         uint32_t entry_count;
68
69         /* Name-hash cache (or NULL if not present). */
70         uint32_t *hashes;
71
72         /*
73          * Extended index.
74          *
75          * When trying to perform bitmap operations with objects that are not
76          * packed in `pack`, these objects are added to this "fake index" and
77          * are assumed to appear at the end of the packfile for all operations
78          */
79         struct eindex {
80                 struct object **objects;
81                 uint32_t *hashes;
82                 uint32_t count, alloc;
83                 khash_sha1_pos *positions;
84         } ext_index;
85
86         /* Bitmap result of the last performed walk */
87         struct bitmap *result;
88
89         /* Version of the bitmap index */
90         unsigned int version;
91
92         unsigned loaded : 1;
93
94 } bitmap_git;
95
96 static struct ewah_bitmap *lookup_stored_bitmap(struct stored_bitmap *st)
97 {
98         struct ewah_bitmap *parent;
99         struct ewah_bitmap *composed;
100
101         if (st->xor == NULL)
102                 return st->root;
103
104         composed = ewah_pool_new();
105         parent = lookup_stored_bitmap(st->xor);
106         ewah_xor(st->root, parent, composed);
107
108         ewah_pool_free(st->root);
109         st->root = composed;
110         st->xor = NULL;
111
112         return composed;
113 }
114
115 /*
116  * Read a bitmap from the current read position on the mmaped
117  * index, and increase the read position accordingly
118  */
119 static struct ewah_bitmap *read_bitmap_1(struct bitmap_index *index)
120 {
121         struct ewah_bitmap *b = ewah_pool_new();
122
123         int bitmap_size = ewah_read_mmap(b,
124                 index->map + index->map_pos,
125                 index->map_size - index->map_pos);
126
127         if (bitmap_size < 0) {
128                 error("Failed to load bitmap index (corrupted?)");
129                 ewah_pool_free(b);
130                 return NULL;
131         }
132
133         index->map_pos += bitmap_size;
134         return b;
135 }
136
137 static int load_bitmap_header(struct bitmap_index *index)
138 {
139         struct bitmap_disk_header *header = (void *)index->map;
140
141         if (index->map_size < sizeof(*header) + 20)
142                 return error("Corrupted bitmap index (missing header data)");
143
144         if (memcmp(header->magic, BITMAP_IDX_SIGNATURE, sizeof(BITMAP_IDX_SIGNATURE)) != 0)
145                 return error("Corrupted bitmap index file (wrong header)");
146
147         index->version = ntohs(header->version);
148         if (index->version != 1)
149                 return error("Unsupported version for bitmap index file (%d)", index->version);
150
151         /* Parse known bitmap format options */
152         {
153                 uint32_t flags = ntohs(header->options);
154
155                 if ((flags & BITMAP_OPT_FULL_DAG) == 0)
156                         return error("Unsupported options for bitmap index file "
157                                 "(Git requires BITMAP_OPT_FULL_DAG)");
158
159                 if (flags & BITMAP_OPT_HASH_CACHE) {
160                         unsigned char *end = index->map + index->map_size - 20;
161                         index->hashes = ((uint32_t *)end) - index->pack->num_objects;
162                 }
163         }
164
165         index->entry_count = ntohl(header->entry_count);
166         index->map_pos += sizeof(*header);
167         return 0;
168 }
169
170 static struct stored_bitmap *store_bitmap(struct bitmap_index *index,
171                                           struct ewah_bitmap *root,
172                                           const unsigned char *sha1,
173                                           struct stored_bitmap *xor_with,
174                                           int flags)
175 {
176         struct stored_bitmap *stored;
177         khiter_t hash_pos;
178         int ret;
179
180         stored = xmalloc(sizeof(struct stored_bitmap));
181         stored->root = root;
182         stored->xor = xor_with;
183         stored->flags = flags;
184         hashcpy(stored->sha1, sha1);
185
186         hash_pos = kh_put_sha1(index->bitmaps, stored->sha1, &ret);
187
188         /* a 0 return code means the insertion succeeded with no changes,
189          * because the SHA1 already existed on the map. this is bad, there
190          * shouldn't be duplicated commits in the index */
191         if (ret == 0) {
192                 error("Duplicate entry in bitmap index: %s", sha1_to_hex(sha1));
193                 return NULL;
194         }
195
196         kh_value(index->bitmaps, hash_pos) = stored;
197         return stored;
198 }
199
200 static inline uint32_t read_be32(const unsigned char *buffer, size_t *pos)
201 {
202         uint32_t result = get_be32(buffer + *pos);
203         (*pos) += sizeof(result);
204         return result;
205 }
206
207 static inline uint8_t read_u8(const unsigned char *buffer, size_t *pos)
208 {
209         return buffer[(*pos)++];
210 }
211
212 #define MAX_XOR_OFFSET 160
213
214 static int load_bitmap_entries_v1(struct bitmap_index *index)
215 {
216         uint32_t i;
217         struct stored_bitmap *recent_bitmaps[MAX_XOR_OFFSET] = { NULL };
218
219         for (i = 0; i < index->entry_count; ++i) {
220                 int xor_offset, flags;
221                 struct ewah_bitmap *bitmap = NULL;
222                 struct stored_bitmap *xor_bitmap = NULL;
223                 uint32_t commit_idx_pos;
224                 const unsigned char *sha1;
225
226                 commit_idx_pos = read_be32(index->map, &index->map_pos);
227                 xor_offset = read_u8(index->map, &index->map_pos);
228                 flags = read_u8(index->map, &index->map_pos);
229
230                 sha1 = nth_packed_object_sha1(index->pack, commit_idx_pos);
231
232                 bitmap = read_bitmap_1(index);
233                 if (!bitmap)
234                         return -1;
235
236                 if (xor_offset > MAX_XOR_OFFSET || xor_offset > i)
237                         return error("Corrupted bitmap pack index");
238
239                 if (xor_offset > 0) {
240                         xor_bitmap = recent_bitmaps[(i - xor_offset) % MAX_XOR_OFFSET];
241
242                         if (xor_bitmap == NULL)
243                                 return error("Invalid XOR offset in bitmap pack index");
244                 }
245
246                 recent_bitmaps[i % MAX_XOR_OFFSET] = store_bitmap(
247                         index, bitmap, sha1, xor_bitmap, flags);
248         }
249
250         return 0;
251 }
252
253 static char *pack_bitmap_filename(struct packed_git *p)
254 {
255         size_t len;
256
257         if (!strip_suffix(p->pack_name, ".pack", &len))
258                 die("BUG: pack_name does not end in .pack");
259         return xstrfmt("%.*s.bitmap", (int)len, p->pack_name);
260 }
261
262 static int open_pack_bitmap_1(struct packed_git *packfile)
263 {
264         int fd;
265         struct stat st;
266         char *idx_name;
267
268         if (open_pack_index(packfile))
269                 return -1;
270
271         idx_name = pack_bitmap_filename(packfile);
272         fd = git_open_noatime(idx_name);
273         free(idx_name);
274
275         if (fd < 0)
276                 return -1;
277
278         if (fstat(fd, &st)) {
279                 close(fd);
280                 return -1;
281         }
282
283         if (bitmap_git.pack) {
284                 warning("ignoring extra bitmap file: %s", packfile->pack_name);
285                 close(fd);
286                 return -1;
287         }
288
289         bitmap_git.pack = packfile;
290         bitmap_git.map_size = xsize_t(st.st_size);
291         bitmap_git.map = xmmap(NULL, bitmap_git.map_size, PROT_READ, MAP_PRIVATE, fd, 0);
292         bitmap_git.map_pos = 0;
293         close(fd);
294
295         if (load_bitmap_header(&bitmap_git) < 0) {
296                 munmap(bitmap_git.map, bitmap_git.map_size);
297                 bitmap_git.map = NULL;
298                 bitmap_git.map_size = 0;
299                 return -1;
300         }
301
302         return 0;
303 }
304
305 static int load_pack_bitmap(void)
306 {
307         assert(bitmap_git.map && !bitmap_git.loaded);
308
309         bitmap_git.bitmaps = kh_init_sha1();
310         bitmap_git.ext_index.positions = kh_init_sha1_pos();
311         bitmap_git.reverse_index = revindex_for_pack(bitmap_git.pack);
312
313         if (!(bitmap_git.commits = read_bitmap_1(&bitmap_git)) ||
314                 !(bitmap_git.trees = read_bitmap_1(&bitmap_git)) ||
315                 !(bitmap_git.blobs = read_bitmap_1(&bitmap_git)) ||
316                 !(bitmap_git.tags = read_bitmap_1(&bitmap_git)))
317                 goto failed;
318
319         if (load_bitmap_entries_v1(&bitmap_git) < 0)
320                 goto failed;
321
322         bitmap_git.loaded = 1;
323         return 0;
324
325 failed:
326         munmap(bitmap_git.map, bitmap_git.map_size);
327         bitmap_git.map = NULL;
328         bitmap_git.map_size = 0;
329         return -1;
330 }
331
332 static int open_pack_bitmap(void)
333 {
334         struct packed_git *p;
335         int ret = -1;
336
337         assert(!bitmap_git.map && !bitmap_git.loaded);
338
339         prepare_packed_git();
340         for (p = packed_git; p; p = p->next) {
341                 if (open_pack_bitmap_1(p) == 0)
342                         ret = 0;
343         }
344
345         return ret;
346 }
347
348 int prepare_bitmap_git(void)
349 {
350         if (bitmap_git.loaded)
351                 return 0;
352
353         if (!open_pack_bitmap())
354                 return load_pack_bitmap();
355
356         return -1;
357 }
358
359 struct include_data {
360         struct bitmap *base;
361         struct bitmap *seen;
362 };
363
364 static inline int bitmap_position_extended(const unsigned char *sha1)
365 {
366         khash_sha1_pos *positions = bitmap_git.ext_index.positions;
367         khiter_t pos = kh_get_sha1_pos(positions, sha1);
368
369         if (pos < kh_end(positions)) {
370                 int bitmap_pos = kh_value(positions, pos);
371                 return bitmap_pos + bitmap_git.pack->num_objects;
372         }
373
374         return -1;
375 }
376
377 static inline int bitmap_position_packfile(const unsigned char *sha1)
378 {
379         off_t offset = find_pack_entry_one(sha1, bitmap_git.pack);
380         if (!offset)
381                 return -1;
382
383         return find_revindex_position(bitmap_git.reverse_index, offset);
384 }
385
386 static int bitmap_position(const unsigned char *sha1)
387 {
388         int pos = bitmap_position_packfile(sha1);
389         return (pos >= 0) ? pos : bitmap_position_extended(sha1);
390 }
391
392 static int ext_index_add_object(struct object *object, const char *name)
393 {
394         struct eindex *eindex = &bitmap_git.ext_index;
395
396         khiter_t hash_pos;
397         int hash_ret;
398         int bitmap_pos;
399
400         hash_pos = kh_put_sha1_pos(eindex->positions, object->oid.hash, &hash_ret);
401         if (hash_ret > 0) {
402                 if (eindex->count >= eindex->alloc) {
403                         eindex->alloc = (eindex->alloc + 16) * 3 / 2;
404                         REALLOC_ARRAY(eindex->objects, eindex->alloc);
405                         REALLOC_ARRAY(eindex->hashes, eindex->alloc);
406                 }
407
408                 bitmap_pos = eindex->count;
409                 eindex->objects[eindex->count] = object;
410                 eindex->hashes[eindex->count] = pack_name_hash(name);
411                 kh_value(eindex->positions, hash_pos) = bitmap_pos;
412                 eindex->count++;
413         } else {
414                 bitmap_pos = kh_value(eindex->positions, hash_pos);
415         }
416
417         return bitmap_pos + bitmap_git.pack->num_objects;
418 }
419
420 static void show_object(struct object *object, const char *name, void *data)
421 {
422         struct bitmap *base = data;
423         int bitmap_pos;
424
425         bitmap_pos = bitmap_position(object->oid.hash);
426
427         if (bitmap_pos < 0)
428                 bitmap_pos = ext_index_add_object(object, name);
429
430         bitmap_set(base, bitmap_pos);
431 }
432
433 static void show_commit(struct commit *commit, void *data)
434 {
435 }
436
437 static int add_to_include_set(struct include_data *data,
438                               const unsigned char *sha1,
439                               int bitmap_pos)
440 {
441         khiter_t hash_pos;
442
443         if (data->seen && bitmap_get(data->seen, bitmap_pos))
444                 return 0;
445
446         if (bitmap_get(data->base, bitmap_pos))
447                 return 0;
448
449         hash_pos = kh_get_sha1(bitmap_git.bitmaps, sha1);
450         if (hash_pos < kh_end(bitmap_git.bitmaps)) {
451                 struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, hash_pos);
452                 bitmap_or_ewah(data->base, lookup_stored_bitmap(st));
453                 return 0;
454         }
455
456         bitmap_set(data->base, bitmap_pos);
457         return 1;
458 }
459
460 static int should_include(struct commit *commit, void *_data)
461 {
462         struct include_data *data = _data;
463         int bitmap_pos;
464
465         bitmap_pos = bitmap_position(commit->object.oid.hash);
466         if (bitmap_pos < 0)
467                 bitmap_pos = ext_index_add_object((struct object *)commit, NULL);
468
469         if (!add_to_include_set(data, commit->object.oid.hash, bitmap_pos)) {
470                 struct commit_list *parent = commit->parents;
471
472                 while (parent) {
473                         parent->item->object.flags |= SEEN;
474                         parent = parent->next;
475                 }
476
477                 return 0;
478         }
479
480         return 1;
481 }
482
483 static struct bitmap *find_objects(struct rev_info *revs,
484                                    struct object_list *roots,
485                                    struct bitmap *seen)
486 {
487         struct bitmap *base = NULL;
488         int needs_walk = 0;
489
490         struct object_list *not_mapped = NULL;
491
492         /*
493          * Go through all the roots for the walk. The ones that have bitmaps
494          * on the bitmap index will be `or`ed together to form an initial
495          * global reachability analysis.
496          *
497          * The ones without bitmaps in the index will be stored in the
498          * `not_mapped_list` for further processing.
499          */
500         while (roots) {
501                 struct object *object = roots->item;
502                 roots = roots->next;
503
504                 if (object->type == OBJ_COMMIT) {
505                         khiter_t pos = kh_get_sha1(bitmap_git.bitmaps, object->oid.hash);
506
507                         if (pos < kh_end(bitmap_git.bitmaps)) {
508                                 struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, pos);
509                                 struct ewah_bitmap *or_with = lookup_stored_bitmap(st);
510
511                                 if (base == NULL)
512                                         base = ewah_to_bitmap(or_with);
513                                 else
514                                         bitmap_or_ewah(base, or_with);
515
516                                 object->flags |= SEEN;
517                                 continue;
518                         }
519                 }
520
521                 object_list_insert(object, &not_mapped);
522         }
523
524         /*
525          * Best case scenario: We found bitmaps for all the roots,
526          * so the resulting `or` bitmap has the full reachability analysis
527          */
528         if (not_mapped == NULL)
529                 return base;
530
531         roots = not_mapped;
532
533         /*
534          * Let's iterate through all the roots that don't have bitmaps to
535          * check if we can determine them to be reachable from the existing
536          * global bitmap.
537          *
538          * If we cannot find them in the existing global bitmap, we'll need
539          * to push them to an actual walk and run it until we can confirm
540          * they are reachable
541          */
542         while (roots) {
543                 struct object *object = roots->item;
544                 int pos;
545
546                 roots = roots->next;
547                 pos = bitmap_position(object->oid.hash);
548
549                 if (pos < 0 || base == NULL || !bitmap_get(base, pos)) {
550                         object->flags &= ~UNINTERESTING;
551                         add_pending_object(revs, object, "");
552                         needs_walk = 1;
553                 } else {
554                         object->flags |= SEEN;
555                 }
556         }
557
558         if (needs_walk) {
559                 struct include_data incdata;
560
561                 if (base == NULL)
562                         base = bitmap_new();
563
564                 incdata.base = base;
565                 incdata.seen = seen;
566
567                 revs->include_check = should_include;
568                 revs->include_check_data = &incdata;
569
570                 if (prepare_revision_walk(revs))
571                         die("revision walk setup failed");
572
573                 traverse_commit_list(revs, show_commit, show_object, base);
574         }
575
576         return base;
577 }
578
579 static void show_extended_objects(struct bitmap *objects,
580                                   show_reachable_fn show_reach)
581 {
582         struct eindex *eindex = &bitmap_git.ext_index;
583         uint32_t i;
584
585         for (i = 0; i < eindex->count; ++i) {
586                 struct object *obj;
587
588                 if (!bitmap_get(objects, bitmap_git.pack->num_objects + i))
589                         continue;
590
591                 obj = eindex->objects[i];
592                 show_reach(obj->oid.hash, obj->type, 0, eindex->hashes[i], NULL, 0);
593         }
594 }
595
596 static void show_objects_for_type(
597         struct bitmap *objects,
598         struct ewah_bitmap *type_filter,
599         enum object_type object_type,
600         show_reachable_fn show_reach)
601 {
602         size_t pos = 0, i = 0;
603         uint32_t offset;
604
605         struct ewah_iterator it;
606         eword_t filter;
607
608         if (bitmap_git.reuse_objects == bitmap_git.pack->num_objects)
609                 return;
610
611         ewah_iterator_init(&it, type_filter);
612
613         while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) {
614                 eword_t word = objects->words[i] & filter;
615
616                 for (offset = 0; offset < BITS_IN_EWORD; ++offset) {
617                         const unsigned char *sha1;
618                         struct revindex_entry *entry;
619                         uint32_t hash = 0;
620
621                         if ((word >> offset) == 0)
622                                 break;
623
624                         offset += ewah_bit_ctz64(word >> offset);
625
626                         if (pos + offset < bitmap_git.reuse_objects)
627                                 continue;
628
629                         entry = &bitmap_git.reverse_index->revindex[pos + offset];
630                         sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
631
632                         if (bitmap_git.hashes)
633                                 hash = ntohl(bitmap_git.hashes[entry->nr]);
634
635                         show_reach(sha1, object_type, 0, hash, bitmap_git.pack, entry->offset);
636                 }
637
638                 pos += BITS_IN_EWORD;
639                 i++;
640         }
641 }
642
643 static int in_bitmapped_pack(struct object_list *roots)
644 {
645         while (roots) {
646                 struct object *object = roots->item;
647                 roots = roots->next;
648
649                 if (find_pack_entry_one(object->oid.hash, bitmap_git.pack) > 0)
650                         return 1;
651         }
652
653         return 0;
654 }
655
656 int prepare_bitmap_walk(struct rev_info *revs)
657 {
658         unsigned int i;
659         unsigned int pending_nr = revs->pending.nr;
660         struct object_array_entry *pending_e = revs->pending.objects;
661
662         struct object_list *wants = NULL;
663         struct object_list *haves = NULL;
664
665         struct bitmap *wants_bitmap = NULL;
666         struct bitmap *haves_bitmap = NULL;
667
668         if (!bitmap_git.loaded) {
669                 /* try to open a bitmapped pack, but don't parse it yet
670                  * because we may not need to use it */
671                 if (open_pack_bitmap() < 0)
672                         return -1;
673         }
674
675         for (i = 0; i < pending_nr; ++i) {
676                 struct object *object = pending_e[i].item;
677
678                 if (object->type == OBJ_NONE)
679                         parse_object_or_die(object->oid.hash, NULL);
680
681                 while (object->type == OBJ_TAG) {
682                         struct tag *tag = (struct tag *) object;
683
684                         if (object->flags & UNINTERESTING)
685                                 object_list_insert(object, &haves);
686                         else
687                                 object_list_insert(object, &wants);
688
689                         if (!tag->tagged)
690                                 die("bad tag");
691                         object = parse_object_or_die(tag->tagged->oid.hash, NULL);
692                 }
693
694                 if (object->flags & UNINTERESTING)
695                         object_list_insert(object, &haves);
696                 else
697                         object_list_insert(object, &wants);
698         }
699
700         /*
701          * if we have a HAVES list, but none of those haves is contained
702          * in the packfile that has a bitmap, we don't have anything to
703          * optimize here
704          */
705         if (haves && !in_bitmapped_pack(haves))
706                 return -1;
707
708         /* if we don't want anything, we're done here */
709         if (!wants)
710                 return -1;
711
712         /*
713          * now we're going to use bitmaps, so load the actual bitmap entries
714          * from disk. this is the point of no return; after this the rev_list
715          * becomes invalidated and we must perform the revwalk through bitmaps
716          */
717         if (!bitmap_git.loaded && load_pack_bitmap() < 0)
718                 return -1;
719
720         revs->pending.nr = 0;
721         revs->pending.alloc = 0;
722         revs->pending.objects = NULL;
723
724         if (haves) {
725                 revs->ignore_missing_links = 1;
726                 haves_bitmap = find_objects(revs, haves, NULL);
727                 reset_revision_walk();
728                 revs->ignore_missing_links = 0;
729
730                 if (haves_bitmap == NULL)
731                         die("BUG: failed to perform bitmap walk");
732         }
733
734         wants_bitmap = find_objects(revs, wants, haves_bitmap);
735
736         if (!wants_bitmap)
737                 die("BUG: failed to perform bitmap walk");
738
739         if (haves_bitmap)
740                 bitmap_and_not(wants_bitmap, haves_bitmap);
741
742         bitmap_git.result = wants_bitmap;
743
744         bitmap_free(haves_bitmap);
745         return 0;
746 }
747
748 int reuse_partial_packfile_from_bitmap(struct packed_git **packfile,
749                                        uint32_t *entries,
750                                        off_t *up_to)
751 {
752         /*
753          * Reuse the packfile content if we need more than
754          * 90% of its objects
755          */
756         static const double REUSE_PERCENT = 0.9;
757
758         struct bitmap *result = bitmap_git.result;
759         uint32_t reuse_threshold;
760         uint32_t i, reuse_objects = 0;
761
762         assert(result);
763
764         for (i = 0; i < result->word_alloc; ++i) {
765                 if (result->words[i] != (eword_t)~0) {
766                         reuse_objects += ewah_bit_ctz64(~result->words[i]);
767                         break;
768                 }
769
770                 reuse_objects += BITS_IN_EWORD;
771         }
772
773 #ifdef GIT_BITMAP_DEBUG
774         {
775                 const unsigned char *sha1;
776                 struct revindex_entry *entry;
777
778                 entry = &bitmap_git.reverse_index->revindex[reuse_objects];
779                 sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
780
781                 fprintf(stderr, "Failed to reuse at %d (%016llx)\n",
782                         reuse_objects, result->words[i]);
783                 fprintf(stderr, " %s\n", sha1_to_hex(sha1));
784         }
785 #endif
786
787         if (!reuse_objects)
788                 return -1;
789
790         if (reuse_objects >= bitmap_git.pack->num_objects) {
791                 bitmap_git.reuse_objects = *entries = bitmap_git.pack->num_objects;
792                 *up_to = -1; /* reuse the full pack */
793                 *packfile = bitmap_git.pack;
794                 return 0;
795         }
796
797         reuse_threshold = bitmap_popcount(bitmap_git.result) * REUSE_PERCENT;
798
799         if (reuse_objects < reuse_threshold)
800                 return -1;
801
802         bitmap_git.reuse_objects = *entries = reuse_objects;
803         *up_to = bitmap_git.reverse_index->revindex[reuse_objects].offset;
804         *packfile = bitmap_git.pack;
805
806         return 0;
807 }
808
809 void traverse_bitmap_commit_list(show_reachable_fn show_reachable)
810 {
811         assert(bitmap_git.result);
812
813         show_objects_for_type(bitmap_git.result, bitmap_git.commits,
814                 OBJ_COMMIT, show_reachable);
815         show_objects_for_type(bitmap_git.result, bitmap_git.trees,
816                 OBJ_TREE, show_reachable);
817         show_objects_for_type(bitmap_git.result, bitmap_git.blobs,
818                 OBJ_BLOB, show_reachable);
819         show_objects_for_type(bitmap_git.result, bitmap_git.tags,
820                 OBJ_TAG, show_reachable);
821
822         show_extended_objects(bitmap_git.result, show_reachable);
823
824         bitmap_free(bitmap_git.result);
825         bitmap_git.result = NULL;
826 }
827
828 static uint32_t count_object_type(struct bitmap *objects,
829                                   enum object_type type)
830 {
831         struct eindex *eindex = &bitmap_git.ext_index;
832
833         uint32_t i = 0, count = 0;
834         struct ewah_iterator it;
835         eword_t filter;
836
837         switch (type) {
838         case OBJ_COMMIT:
839                 ewah_iterator_init(&it, bitmap_git.commits);
840                 break;
841
842         case OBJ_TREE:
843                 ewah_iterator_init(&it, bitmap_git.trees);
844                 break;
845
846         case OBJ_BLOB:
847                 ewah_iterator_init(&it, bitmap_git.blobs);
848                 break;
849
850         case OBJ_TAG:
851                 ewah_iterator_init(&it, bitmap_git.tags);
852                 break;
853
854         default:
855                 return 0;
856         }
857
858         while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) {
859                 eword_t word = objects->words[i++] & filter;
860                 count += ewah_bit_popcount64(word);
861         }
862
863         for (i = 0; i < eindex->count; ++i) {
864                 if (eindex->objects[i]->type == type &&
865                         bitmap_get(objects, bitmap_git.pack->num_objects + i))
866                         count++;
867         }
868
869         return count;
870 }
871
872 void count_bitmap_commit_list(uint32_t *commits, uint32_t *trees,
873                               uint32_t *blobs, uint32_t *tags)
874 {
875         assert(bitmap_git.result);
876
877         if (commits)
878                 *commits = count_object_type(bitmap_git.result, OBJ_COMMIT);
879
880         if (trees)
881                 *trees = count_object_type(bitmap_git.result, OBJ_TREE);
882
883         if (blobs)
884                 *blobs = count_object_type(bitmap_git.result, OBJ_BLOB);
885
886         if (tags)
887                 *tags = count_object_type(bitmap_git.result, OBJ_TAG);
888 }
889
890 struct bitmap_test_data {
891         struct bitmap *base;
892         struct progress *prg;
893         size_t seen;
894 };
895
896 static void test_show_object(struct object *object, const char *name,
897                              void *data)
898 {
899         struct bitmap_test_data *tdata = data;
900         int bitmap_pos;
901
902         bitmap_pos = bitmap_position(object->oid.hash);
903         if (bitmap_pos < 0)
904                 die("Object not in bitmap: %s\n", oid_to_hex(&object->oid));
905
906         bitmap_set(tdata->base, bitmap_pos);
907         display_progress(tdata->prg, ++tdata->seen);
908 }
909
910 static void test_show_commit(struct commit *commit, void *data)
911 {
912         struct bitmap_test_data *tdata = data;
913         int bitmap_pos;
914
915         bitmap_pos = bitmap_position(commit->object.oid.hash);
916         if (bitmap_pos < 0)
917                 die("Object not in bitmap: %s\n", oid_to_hex(&commit->object.oid));
918
919         bitmap_set(tdata->base, bitmap_pos);
920         display_progress(tdata->prg, ++tdata->seen);
921 }
922
923 void test_bitmap_walk(struct rev_info *revs)
924 {
925         struct object *root;
926         struct bitmap *result = NULL;
927         khiter_t pos;
928         size_t result_popcnt;
929         struct bitmap_test_data tdata;
930
931         if (prepare_bitmap_git())
932                 die("failed to load bitmap indexes");
933
934         if (revs->pending.nr != 1)
935                 die("you must specify exactly one commit to test");
936
937         fprintf(stderr, "Bitmap v%d test (%d entries loaded)\n",
938                 bitmap_git.version, bitmap_git.entry_count);
939
940         root = revs->pending.objects[0].item;
941         pos = kh_get_sha1(bitmap_git.bitmaps, root->oid.hash);
942
943         if (pos < kh_end(bitmap_git.bitmaps)) {
944                 struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, pos);
945                 struct ewah_bitmap *bm = lookup_stored_bitmap(st);
946
947                 fprintf(stderr, "Found bitmap for %s. %d bits / %08x checksum\n",
948                         oid_to_hex(&root->oid), (int)bm->bit_size, ewah_checksum(bm));
949
950                 result = ewah_to_bitmap(bm);
951         }
952
953         if (result == NULL)
954                 die("Commit %s doesn't have an indexed bitmap", oid_to_hex(&root->oid));
955
956         revs->tag_objects = 1;
957         revs->tree_objects = 1;
958         revs->blob_objects = 1;
959
960         result_popcnt = bitmap_popcount(result);
961
962         if (prepare_revision_walk(revs))
963                 die("revision walk setup failed");
964
965         tdata.base = bitmap_new();
966         tdata.prg = start_progress("Verifying bitmap entries", result_popcnt);
967         tdata.seen = 0;
968
969         traverse_commit_list(revs, &test_show_commit, &test_show_object, &tdata);
970
971         stop_progress(&tdata.prg);
972
973         if (bitmap_equals(result, tdata.base))
974                 fprintf(stderr, "OK!\n");
975         else
976                 fprintf(stderr, "Mismatch!\n");
977
978         bitmap_free(result);
979 }
980
981 static int rebuild_bitmap(uint32_t *reposition,
982                           struct ewah_bitmap *source,
983                           struct bitmap *dest)
984 {
985         uint32_t pos = 0;
986         struct ewah_iterator it;
987         eword_t word;
988
989         ewah_iterator_init(&it, source);
990
991         while (ewah_iterator_next(&word, &it)) {
992                 uint32_t offset, bit_pos;
993
994                 for (offset = 0; offset < BITS_IN_EWORD; ++offset) {
995                         if ((word >> offset) == 0)
996                                 break;
997
998                         offset += ewah_bit_ctz64(word >> offset);
999
1000                         bit_pos = reposition[pos + offset];
1001                         if (bit_pos > 0)
1002                                 bitmap_set(dest, bit_pos - 1);
1003                         else /* can't reuse, we don't have the object */
1004                                 return -1;
1005                 }
1006
1007                 pos += BITS_IN_EWORD;
1008         }
1009         return 0;
1010 }
1011
1012 int rebuild_existing_bitmaps(struct packing_data *mapping,
1013                              khash_sha1 *reused_bitmaps,
1014                              int show_progress)
1015 {
1016         uint32_t i, num_objects;
1017         uint32_t *reposition;
1018         struct bitmap *rebuild;
1019         struct stored_bitmap *stored;
1020         struct progress *progress = NULL;
1021
1022         khiter_t hash_pos;
1023         int hash_ret;
1024
1025         if (prepare_bitmap_git() < 0)
1026                 return -1;
1027
1028         num_objects = bitmap_git.pack->num_objects;
1029         reposition = xcalloc(num_objects, sizeof(uint32_t));
1030
1031         for (i = 0; i < num_objects; ++i) {
1032                 const unsigned char *sha1;
1033                 struct revindex_entry *entry;
1034                 struct object_entry *oe;
1035
1036                 entry = &bitmap_git.reverse_index->revindex[i];
1037                 sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
1038                 oe = packlist_find(mapping, sha1, NULL);
1039
1040                 if (oe)
1041                         reposition[i] = oe->in_pack_pos + 1;
1042         }
1043
1044         rebuild = bitmap_new();
1045         i = 0;
1046
1047         if (show_progress)
1048                 progress = start_progress("Reusing bitmaps", 0);
1049
1050         kh_foreach_value(bitmap_git.bitmaps, stored, {
1051                 if (stored->flags & BITMAP_FLAG_REUSE) {
1052                         if (!rebuild_bitmap(reposition,
1053                                             lookup_stored_bitmap(stored),
1054                                             rebuild)) {
1055                                 hash_pos = kh_put_sha1(reused_bitmaps,
1056                                                        stored->sha1,
1057                                                        &hash_ret);
1058                                 kh_value(reused_bitmaps, hash_pos) =
1059                                         bitmap_to_ewah(rebuild);
1060                         }
1061                         bitmap_reset(rebuild);
1062                         display_progress(progress, ++i);
1063                 }
1064         });
1065
1066         stop_progress(&progress);
1067
1068         free(reposition);
1069         bitmap_free(rebuild);
1070         return 0;
1071 }