Merge branch 'nd/stop-setenv-work-tree' into nd/clear-gitenv-upon-use-of-alias
[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         char *idx_name;
256         int len;
257
258         len = strlen(p->pack_name) - strlen(".pack");
259         idx_name = xmalloc(len + strlen(".bitmap") + 1);
260
261         memcpy(idx_name, p->pack_name, len);
262         memcpy(idx_name + len, ".bitmap", strlen(".bitmap") + 1);
263
264         return idx_name;
265 }
266
267 static int open_pack_bitmap_1(struct packed_git *packfile)
268 {
269         int fd;
270         struct stat st;
271         char *idx_name;
272
273         if (open_pack_index(packfile))
274                 return -1;
275
276         idx_name = pack_bitmap_filename(packfile);
277         fd = git_open_noatime(idx_name);
278         free(idx_name);
279
280         if (fd < 0)
281                 return -1;
282
283         if (fstat(fd, &st)) {
284                 close(fd);
285                 return -1;
286         }
287
288         if (bitmap_git.pack) {
289                 warning("ignoring extra bitmap file: %s", packfile->pack_name);
290                 close(fd);
291                 return -1;
292         }
293
294         bitmap_git.pack = packfile;
295         bitmap_git.map_size = xsize_t(st.st_size);
296         bitmap_git.map = xmmap(NULL, bitmap_git.map_size, PROT_READ, MAP_PRIVATE, fd, 0);
297         bitmap_git.map_pos = 0;
298         close(fd);
299
300         if (load_bitmap_header(&bitmap_git) < 0) {
301                 munmap(bitmap_git.map, bitmap_git.map_size);
302                 bitmap_git.map = NULL;
303                 bitmap_git.map_size = 0;
304                 return -1;
305         }
306
307         return 0;
308 }
309
310 static int load_pack_bitmap(void)
311 {
312         assert(bitmap_git.map && !bitmap_git.loaded);
313
314         bitmap_git.bitmaps = kh_init_sha1();
315         bitmap_git.ext_index.positions = kh_init_sha1_pos();
316         bitmap_git.reverse_index = revindex_for_pack(bitmap_git.pack);
317
318         if (!(bitmap_git.commits = read_bitmap_1(&bitmap_git)) ||
319                 !(bitmap_git.trees = read_bitmap_1(&bitmap_git)) ||
320                 !(bitmap_git.blobs = read_bitmap_1(&bitmap_git)) ||
321                 !(bitmap_git.tags = read_bitmap_1(&bitmap_git)))
322                 goto failed;
323
324         if (load_bitmap_entries_v1(&bitmap_git) < 0)
325                 goto failed;
326
327         bitmap_git.loaded = 1;
328         return 0;
329
330 failed:
331         munmap(bitmap_git.map, bitmap_git.map_size);
332         bitmap_git.map = NULL;
333         bitmap_git.map_size = 0;
334         return -1;
335 }
336
337 static int open_pack_bitmap(void)
338 {
339         struct packed_git *p;
340         int ret = -1;
341
342         assert(!bitmap_git.map && !bitmap_git.loaded);
343
344         prepare_packed_git();
345         for (p = packed_git; p; p = p->next) {
346                 if (open_pack_bitmap_1(p) == 0)
347                         ret = 0;
348         }
349
350         return ret;
351 }
352
353 int prepare_bitmap_git(void)
354 {
355         if (bitmap_git.loaded)
356                 return 0;
357
358         if (!open_pack_bitmap())
359                 return load_pack_bitmap();
360
361         return -1;
362 }
363
364 struct include_data {
365         struct bitmap *base;
366         struct bitmap *seen;
367 };
368
369 static inline int bitmap_position_extended(const unsigned char *sha1)
370 {
371         khash_sha1_pos *positions = bitmap_git.ext_index.positions;
372         khiter_t pos = kh_get_sha1_pos(positions, sha1);
373
374         if (pos < kh_end(positions)) {
375                 int bitmap_pos = kh_value(positions, pos);
376                 return bitmap_pos + bitmap_git.pack->num_objects;
377         }
378
379         return -1;
380 }
381
382 static inline int bitmap_position_packfile(const unsigned char *sha1)
383 {
384         off_t offset = find_pack_entry_one(sha1, bitmap_git.pack);
385         if (!offset)
386                 return -1;
387
388         return find_revindex_position(bitmap_git.reverse_index, offset);
389 }
390
391 static int bitmap_position(const unsigned char *sha1)
392 {
393         int pos = bitmap_position_packfile(sha1);
394         return (pos >= 0) ? pos : bitmap_position_extended(sha1);
395 }
396
397 static int ext_index_add_object(struct object *object, const char *name)
398 {
399         struct eindex *eindex = &bitmap_git.ext_index;
400
401         khiter_t hash_pos;
402         int hash_ret;
403         int bitmap_pos;
404
405         hash_pos = kh_put_sha1_pos(eindex->positions, object->sha1, &hash_ret);
406         if (hash_ret > 0) {
407                 if (eindex->count >= eindex->alloc) {
408                         eindex->alloc = (eindex->alloc + 16) * 3 / 2;
409                         REALLOC_ARRAY(eindex->objects, eindex->alloc);
410                         REALLOC_ARRAY(eindex->hashes, eindex->alloc);
411                 }
412
413                 bitmap_pos = eindex->count;
414                 eindex->objects[eindex->count] = object;
415                 eindex->hashes[eindex->count] = pack_name_hash(name);
416                 kh_value(eindex->positions, hash_pos) = bitmap_pos;
417                 eindex->count++;
418         } else {
419                 bitmap_pos = kh_value(eindex->positions, hash_pos);
420         }
421
422         return bitmap_pos + bitmap_git.pack->num_objects;
423 }
424
425 static void show_object(struct object *object, const struct name_path *path,
426                         const char *last, void *data)
427 {
428         struct bitmap *base = data;
429         int bitmap_pos;
430
431         bitmap_pos = bitmap_position(object->sha1);
432
433         if (bitmap_pos < 0) {
434                 char *name = path_name(path, last);
435                 bitmap_pos = ext_index_add_object(object, name);
436                 free(name);
437         }
438
439         bitmap_set(base, bitmap_pos);
440 }
441
442 static void show_commit(struct commit *commit, void *data)
443 {
444 }
445
446 static int add_to_include_set(struct include_data *data,
447                               const unsigned char *sha1,
448                               int bitmap_pos)
449 {
450         khiter_t hash_pos;
451
452         if (data->seen && bitmap_get(data->seen, bitmap_pos))
453                 return 0;
454
455         if (bitmap_get(data->base, bitmap_pos))
456                 return 0;
457
458         hash_pos = kh_get_sha1(bitmap_git.bitmaps, sha1);
459         if (hash_pos < kh_end(bitmap_git.bitmaps)) {
460                 struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, hash_pos);
461                 bitmap_or_ewah(data->base, lookup_stored_bitmap(st));
462                 return 0;
463         }
464
465         bitmap_set(data->base, bitmap_pos);
466         return 1;
467 }
468
469 static int should_include(struct commit *commit, void *_data)
470 {
471         struct include_data *data = _data;
472         int bitmap_pos;
473
474         bitmap_pos = bitmap_position(commit->object.sha1);
475         if (bitmap_pos < 0)
476                 bitmap_pos = ext_index_add_object((struct object *)commit, NULL);
477
478         if (!add_to_include_set(data, commit->object.sha1, bitmap_pos)) {
479                 struct commit_list *parent = commit->parents;
480
481                 while (parent) {
482                         parent->item->object.flags |= SEEN;
483                         parent = parent->next;
484                 }
485
486                 return 0;
487         }
488
489         return 1;
490 }
491
492 static struct bitmap *find_objects(struct rev_info *revs,
493                                    struct object_list *roots,
494                                    struct bitmap *seen)
495 {
496         struct bitmap *base = NULL;
497         int needs_walk = 0;
498
499         struct object_list *not_mapped = NULL;
500
501         /*
502          * Go through all the roots for the walk. The ones that have bitmaps
503          * on the bitmap index will be `or`ed together to form an initial
504          * global reachability analysis.
505          *
506          * The ones without bitmaps in the index will be stored in the
507          * `not_mapped_list` for further processing.
508          */
509         while (roots) {
510                 struct object *object = roots->item;
511                 roots = roots->next;
512
513                 if (object->type == OBJ_COMMIT) {
514                         khiter_t pos = kh_get_sha1(bitmap_git.bitmaps, object->sha1);
515
516                         if (pos < kh_end(bitmap_git.bitmaps)) {
517                                 struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, pos);
518                                 struct ewah_bitmap *or_with = lookup_stored_bitmap(st);
519
520                                 if (base == NULL)
521                                         base = ewah_to_bitmap(or_with);
522                                 else
523                                         bitmap_or_ewah(base, or_with);
524
525                                 object->flags |= SEEN;
526                                 continue;
527                         }
528                 }
529
530                 object_list_insert(object, &not_mapped);
531         }
532
533         /*
534          * Best case scenario: We found bitmaps for all the roots,
535          * so the resulting `or` bitmap has the full reachability analysis
536          */
537         if (not_mapped == NULL)
538                 return base;
539
540         roots = not_mapped;
541
542         /*
543          * Let's iterate through all the roots that don't have bitmaps to
544          * check if we can determine them to be reachable from the existing
545          * global bitmap.
546          *
547          * If we cannot find them in the existing global bitmap, we'll need
548          * to push them to an actual walk and run it until we can confirm
549          * they are reachable
550          */
551         while (roots) {
552                 struct object *object = roots->item;
553                 int pos;
554
555                 roots = roots->next;
556                 pos = bitmap_position(object->sha1);
557
558                 if (pos < 0 || base == NULL || !bitmap_get(base, pos)) {
559                         object->flags &= ~UNINTERESTING;
560                         add_pending_object(revs, object, "");
561                         needs_walk = 1;
562                 } else {
563                         object->flags |= SEEN;
564                 }
565         }
566
567         if (needs_walk) {
568                 struct include_data incdata;
569
570                 if (base == NULL)
571                         base = bitmap_new();
572
573                 incdata.base = base;
574                 incdata.seen = seen;
575
576                 revs->include_check = should_include;
577                 revs->include_check_data = &incdata;
578
579                 if (prepare_revision_walk(revs))
580                         die("revision walk setup failed");
581
582                 traverse_commit_list(revs, show_commit, show_object, base);
583         }
584
585         return base;
586 }
587
588 static void show_extended_objects(struct bitmap *objects,
589                                   show_reachable_fn show_reach)
590 {
591         struct eindex *eindex = &bitmap_git.ext_index;
592         uint32_t i;
593
594         for (i = 0; i < eindex->count; ++i) {
595                 struct object *obj;
596
597                 if (!bitmap_get(objects, bitmap_git.pack->num_objects + i))
598                         continue;
599
600                 obj = eindex->objects[i];
601                 show_reach(obj->sha1, obj->type, 0, eindex->hashes[i], NULL, 0);
602         }
603 }
604
605 static void show_objects_for_type(
606         struct bitmap *objects,
607         struct ewah_bitmap *type_filter,
608         enum object_type object_type,
609         show_reachable_fn show_reach)
610 {
611         size_t pos = 0, i = 0;
612         uint32_t offset;
613
614         struct ewah_iterator it;
615         eword_t filter;
616
617         if (bitmap_git.reuse_objects == bitmap_git.pack->num_objects)
618                 return;
619
620         ewah_iterator_init(&it, type_filter);
621
622         while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) {
623                 eword_t word = objects->words[i] & filter;
624
625                 for (offset = 0; offset < BITS_IN_EWORD; ++offset) {
626                         const unsigned char *sha1;
627                         struct revindex_entry *entry;
628                         uint32_t hash = 0;
629
630                         if ((word >> offset) == 0)
631                                 break;
632
633                         offset += ewah_bit_ctz64(word >> offset);
634
635                         if (pos + offset < bitmap_git.reuse_objects)
636                                 continue;
637
638                         entry = &bitmap_git.reverse_index->revindex[pos + offset];
639                         sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
640
641                         if (bitmap_git.hashes)
642                                 hash = ntohl(bitmap_git.hashes[entry->nr]);
643
644                         show_reach(sha1, object_type, 0, hash, bitmap_git.pack, entry->offset);
645                 }
646
647                 pos += BITS_IN_EWORD;
648                 i++;
649         }
650 }
651
652 static int in_bitmapped_pack(struct object_list *roots)
653 {
654         while (roots) {
655                 struct object *object = roots->item;
656                 roots = roots->next;
657
658                 if (find_pack_entry_one(object->sha1, bitmap_git.pack) > 0)
659                         return 1;
660         }
661
662         return 0;
663 }
664
665 int prepare_bitmap_walk(struct rev_info *revs)
666 {
667         unsigned int i;
668         unsigned int pending_nr = revs->pending.nr;
669         struct object_array_entry *pending_e = revs->pending.objects;
670
671         struct object_list *wants = NULL;
672         struct object_list *haves = NULL;
673
674         struct bitmap *wants_bitmap = NULL;
675         struct bitmap *haves_bitmap = NULL;
676
677         if (!bitmap_git.loaded) {
678                 /* try to open a bitmapped pack, but don't parse it yet
679                  * because we may not need to use it */
680                 if (open_pack_bitmap() < 0)
681                         return -1;
682         }
683
684         for (i = 0; i < pending_nr; ++i) {
685                 struct object *object = pending_e[i].item;
686
687                 if (object->type == OBJ_NONE)
688                         parse_object_or_die(object->sha1, NULL);
689
690                 while (object->type == OBJ_TAG) {
691                         struct tag *tag = (struct tag *) object;
692
693                         if (object->flags & UNINTERESTING)
694                                 object_list_insert(object, &haves);
695                         else
696                                 object_list_insert(object, &wants);
697
698                         if (!tag->tagged)
699                                 die("bad tag");
700                         object = parse_object_or_die(tag->tagged->sha1, NULL);
701                 }
702
703                 if (object->flags & UNINTERESTING)
704                         object_list_insert(object, &haves);
705                 else
706                         object_list_insert(object, &wants);
707         }
708
709         /*
710          * if we have a HAVES list, but none of those haves is contained
711          * in the packfile that has a bitmap, we don't have anything to
712          * optimize here
713          */
714         if (haves && !in_bitmapped_pack(haves))
715                 return -1;
716
717         /* if we don't want anything, we're done here */
718         if (!wants)
719                 return -1;
720
721         /*
722          * now we're going to use bitmaps, so load the actual bitmap entries
723          * from disk. this is the point of no return; after this the rev_list
724          * becomes invalidated and we must perform the revwalk through bitmaps
725          */
726         if (!bitmap_git.loaded && load_pack_bitmap() < 0)
727                 return -1;
728
729         revs->pending.nr = 0;
730         revs->pending.alloc = 0;
731         revs->pending.objects = NULL;
732
733         if (haves) {
734                 revs->ignore_missing_links = 1;
735                 haves_bitmap = find_objects(revs, haves, NULL);
736                 reset_revision_walk();
737                 revs->ignore_missing_links = 0;
738
739                 if (haves_bitmap == NULL)
740                         die("BUG: failed to perform bitmap walk");
741         }
742
743         wants_bitmap = find_objects(revs, wants, haves_bitmap);
744
745         if (!wants_bitmap)
746                 die("BUG: failed to perform bitmap walk");
747
748         if (haves_bitmap)
749                 bitmap_and_not(wants_bitmap, haves_bitmap);
750
751         bitmap_git.result = wants_bitmap;
752
753         bitmap_free(haves_bitmap);
754         return 0;
755 }
756
757 int reuse_partial_packfile_from_bitmap(struct packed_git **packfile,
758                                        uint32_t *entries,
759                                        off_t *up_to)
760 {
761         /*
762          * Reuse the packfile content if we need more than
763          * 90% of its objects
764          */
765         static const double REUSE_PERCENT = 0.9;
766
767         struct bitmap *result = bitmap_git.result;
768         uint32_t reuse_threshold;
769         uint32_t i, reuse_objects = 0;
770
771         assert(result);
772
773         for (i = 0; i < result->word_alloc; ++i) {
774                 if (result->words[i] != (eword_t)~0) {
775                         reuse_objects += ewah_bit_ctz64(~result->words[i]);
776                         break;
777                 }
778
779                 reuse_objects += BITS_IN_EWORD;
780         }
781
782 #ifdef GIT_BITMAP_DEBUG
783         {
784                 const unsigned char *sha1;
785                 struct revindex_entry *entry;
786
787                 entry = &bitmap_git.reverse_index->revindex[reuse_objects];
788                 sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
789
790                 fprintf(stderr, "Failed to reuse at %d (%016llx)\n",
791                         reuse_objects, result->words[i]);
792                 fprintf(stderr, " %s\n", sha1_to_hex(sha1));
793         }
794 #endif
795
796         if (!reuse_objects)
797                 return -1;
798
799         if (reuse_objects >= bitmap_git.pack->num_objects) {
800                 bitmap_git.reuse_objects = *entries = bitmap_git.pack->num_objects;
801                 *up_to = -1; /* reuse the full pack */
802                 *packfile = bitmap_git.pack;
803                 return 0;
804         }
805
806         reuse_threshold = bitmap_popcount(bitmap_git.result) * REUSE_PERCENT;
807
808         if (reuse_objects < reuse_threshold)
809                 return -1;
810
811         bitmap_git.reuse_objects = *entries = reuse_objects;
812         *up_to = bitmap_git.reverse_index->revindex[reuse_objects].offset;
813         *packfile = bitmap_git.pack;
814
815         return 0;
816 }
817
818 void traverse_bitmap_commit_list(show_reachable_fn show_reachable)
819 {
820         assert(bitmap_git.result);
821
822         show_objects_for_type(bitmap_git.result, bitmap_git.commits,
823                 OBJ_COMMIT, show_reachable);
824         show_objects_for_type(bitmap_git.result, bitmap_git.trees,
825                 OBJ_TREE, show_reachable);
826         show_objects_for_type(bitmap_git.result, bitmap_git.blobs,
827                 OBJ_BLOB, show_reachable);
828         show_objects_for_type(bitmap_git.result, bitmap_git.tags,
829                 OBJ_TAG, show_reachable);
830
831         show_extended_objects(bitmap_git.result, show_reachable);
832
833         bitmap_free(bitmap_git.result);
834         bitmap_git.result = NULL;
835 }
836
837 static uint32_t count_object_type(struct bitmap *objects,
838                                   enum object_type type)
839 {
840         struct eindex *eindex = &bitmap_git.ext_index;
841
842         uint32_t i = 0, count = 0;
843         struct ewah_iterator it;
844         eword_t filter;
845
846         switch (type) {
847         case OBJ_COMMIT:
848                 ewah_iterator_init(&it, bitmap_git.commits);
849                 break;
850
851         case OBJ_TREE:
852                 ewah_iterator_init(&it, bitmap_git.trees);
853                 break;
854
855         case OBJ_BLOB:
856                 ewah_iterator_init(&it, bitmap_git.blobs);
857                 break;
858
859         case OBJ_TAG:
860                 ewah_iterator_init(&it, bitmap_git.tags);
861                 break;
862
863         default:
864                 return 0;
865         }
866
867         while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) {
868                 eword_t word = objects->words[i++] & filter;
869                 count += ewah_bit_popcount64(word);
870         }
871
872         for (i = 0; i < eindex->count; ++i) {
873                 if (eindex->objects[i]->type == type &&
874                         bitmap_get(objects, bitmap_git.pack->num_objects + i))
875                         count++;
876         }
877
878         return count;
879 }
880
881 void count_bitmap_commit_list(uint32_t *commits, uint32_t *trees,
882                               uint32_t *blobs, uint32_t *tags)
883 {
884         assert(bitmap_git.result);
885
886         if (commits)
887                 *commits = count_object_type(bitmap_git.result, OBJ_COMMIT);
888
889         if (trees)
890                 *trees = count_object_type(bitmap_git.result, OBJ_TREE);
891
892         if (blobs)
893                 *blobs = count_object_type(bitmap_git.result, OBJ_BLOB);
894
895         if (tags)
896                 *tags = count_object_type(bitmap_git.result, OBJ_TAG);
897 }
898
899 struct bitmap_test_data {
900         struct bitmap *base;
901         struct progress *prg;
902         size_t seen;
903 };
904
905 static void test_show_object(struct object *object,
906                              const struct name_path *path,
907                              const char *last, void *data)
908 {
909         struct bitmap_test_data *tdata = data;
910         int bitmap_pos;
911
912         bitmap_pos = bitmap_position(object->sha1);
913         if (bitmap_pos < 0)
914                 die("Object not in bitmap: %s\n", sha1_to_hex(object->sha1));
915
916         bitmap_set(tdata->base, bitmap_pos);
917         display_progress(tdata->prg, ++tdata->seen);
918 }
919
920 static void test_show_commit(struct commit *commit, void *data)
921 {
922         struct bitmap_test_data *tdata = data;
923         int bitmap_pos;
924
925         bitmap_pos = bitmap_position(commit->object.sha1);
926         if (bitmap_pos < 0)
927                 die("Object not in bitmap: %s\n", sha1_to_hex(commit->object.sha1));
928
929         bitmap_set(tdata->base, bitmap_pos);
930         display_progress(tdata->prg, ++tdata->seen);
931 }
932
933 void test_bitmap_walk(struct rev_info *revs)
934 {
935         struct object *root;
936         struct bitmap *result = NULL;
937         khiter_t pos;
938         size_t result_popcnt;
939         struct bitmap_test_data tdata;
940
941         if (prepare_bitmap_git())
942                 die("failed to load bitmap indexes");
943
944         if (revs->pending.nr != 1)
945                 die("you must specify exactly one commit to test");
946
947         fprintf(stderr, "Bitmap v%d test (%d entries loaded)\n",
948                 bitmap_git.version, bitmap_git.entry_count);
949
950         root = revs->pending.objects[0].item;
951         pos = kh_get_sha1(bitmap_git.bitmaps, root->sha1);
952
953         if (pos < kh_end(bitmap_git.bitmaps)) {
954                 struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, pos);
955                 struct ewah_bitmap *bm = lookup_stored_bitmap(st);
956
957                 fprintf(stderr, "Found bitmap for %s. %d bits / %08x checksum\n",
958                         sha1_to_hex(root->sha1), (int)bm->bit_size, ewah_checksum(bm));
959
960                 result = ewah_to_bitmap(bm);
961         }
962
963         if (result == NULL)
964                 die("Commit %s doesn't have an indexed bitmap", sha1_to_hex(root->sha1));
965
966         revs->tag_objects = 1;
967         revs->tree_objects = 1;
968         revs->blob_objects = 1;
969
970         result_popcnt = bitmap_popcount(result);
971
972         if (prepare_revision_walk(revs))
973                 die("revision walk setup failed");
974
975         tdata.base = bitmap_new();
976         tdata.prg = start_progress("Verifying bitmap entries", result_popcnt);
977         tdata.seen = 0;
978
979         traverse_commit_list(revs, &test_show_commit, &test_show_object, &tdata);
980
981         stop_progress(&tdata.prg);
982
983         if (bitmap_equals(result, tdata.base))
984                 fprintf(stderr, "OK!\n");
985         else
986                 fprintf(stderr, "Mismatch!\n");
987
988         bitmap_free(result);
989 }
990
991 static int rebuild_bitmap(uint32_t *reposition,
992                           struct ewah_bitmap *source,
993                           struct bitmap *dest)
994 {
995         uint32_t pos = 0;
996         struct ewah_iterator it;
997         eword_t word;
998
999         ewah_iterator_init(&it, source);
1000
1001         while (ewah_iterator_next(&word, &it)) {
1002                 uint32_t offset, bit_pos;
1003
1004                 for (offset = 0; offset < BITS_IN_EWORD; ++offset) {
1005                         if ((word >> offset) == 0)
1006                                 break;
1007
1008                         offset += ewah_bit_ctz64(word >> offset);
1009
1010                         bit_pos = reposition[pos + offset];
1011                         if (bit_pos > 0)
1012                                 bitmap_set(dest, bit_pos - 1);
1013                         else /* can't reuse, we don't have the object */
1014                                 return -1;
1015                 }
1016
1017                 pos += BITS_IN_EWORD;
1018         }
1019         return 0;
1020 }
1021
1022 int rebuild_existing_bitmaps(struct packing_data *mapping,
1023                              khash_sha1 *reused_bitmaps,
1024                              int show_progress)
1025 {
1026         uint32_t i, num_objects;
1027         uint32_t *reposition;
1028         struct bitmap *rebuild;
1029         struct stored_bitmap *stored;
1030         struct progress *progress = NULL;
1031
1032         khiter_t hash_pos;
1033         int hash_ret;
1034
1035         if (prepare_bitmap_git() < 0)
1036                 return -1;
1037
1038         num_objects = bitmap_git.pack->num_objects;
1039         reposition = xcalloc(num_objects, sizeof(uint32_t));
1040
1041         for (i = 0; i < num_objects; ++i) {
1042                 const unsigned char *sha1;
1043                 struct revindex_entry *entry;
1044                 struct object_entry *oe;
1045
1046                 entry = &bitmap_git.reverse_index->revindex[i];
1047                 sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
1048                 oe = packlist_find(mapping, sha1, NULL);
1049
1050                 if (oe)
1051                         reposition[i] = oe->in_pack_pos + 1;
1052         }
1053
1054         rebuild = bitmap_new();
1055         i = 0;
1056
1057         if (show_progress)
1058                 progress = start_progress("Reusing bitmaps", 0);
1059
1060         kh_foreach_value(bitmap_git.bitmaps, stored, {
1061                 if (stored->flags & BITMAP_FLAG_REUSE) {
1062                         if (!rebuild_bitmap(reposition,
1063                                             lookup_stored_bitmap(stored),
1064                                             rebuild)) {
1065                                 hash_pos = kh_put_sha1(reused_bitmaps,
1066                                                        stored->sha1,
1067                                                        &hash_ret);
1068                                 kh_value(reused_bitmaps, hash_pos) =
1069                                         bitmap_to_ewah(rebuild);
1070                         }
1071                         bitmap_reset(rebuild);
1072                         display_progress(progress, ++i);
1073                 }
1074         });
1075
1076         stop_progress(&progress);
1077
1078         free(reposition);
1079         bitmap_free(rebuild);
1080         return 0;
1081 }