Merge branch 'maint'
[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 comits */
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 int load_bitmap_entries_v1(struct bitmap_index *index)
201 {
202         static const size_t MAX_XOR_OFFSET = 160;
203
204         uint32_t i;
205         struct stored_bitmap **recent_bitmaps;
206         struct bitmap_disk_entry *entry;
207
208         recent_bitmaps = xcalloc(MAX_XOR_OFFSET, sizeof(struct stored_bitmap));
209
210         for (i = 0; i < index->entry_count; ++i) {
211                 int xor_offset, flags;
212                 struct ewah_bitmap *bitmap = NULL;
213                 struct stored_bitmap *xor_bitmap = NULL;
214                 uint32_t commit_idx_pos;
215                 const unsigned char *sha1;
216
217                 entry = (struct bitmap_disk_entry *)(index->map + index->map_pos);
218                 index->map_pos += sizeof(struct bitmap_disk_entry);
219
220                 commit_idx_pos = ntohl(entry->object_pos);
221                 sha1 = nth_packed_object_sha1(index->pack, commit_idx_pos);
222
223                 xor_offset = (int)entry->xor_offset;
224                 flags = (int)entry->flags;
225
226                 bitmap = read_bitmap_1(index);
227                 if (!bitmap)
228                         return -1;
229
230                 if (xor_offset > MAX_XOR_OFFSET || xor_offset > i)
231                         return error("Corrupted bitmap pack index");
232
233                 if (xor_offset > 0) {
234                         xor_bitmap = recent_bitmaps[(i - xor_offset) % MAX_XOR_OFFSET];
235
236                         if (xor_bitmap == NULL)
237                                 return error("Invalid XOR offset in bitmap pack index");
238                 }
239
240                 recent_bitmaps[i % MAX_XOR_OFFSET] = store_bitmap(
241                         index, bitmap, sha1, xor_bitmap, flags);
242         }
243
244         return 0;
245 }
246
247 static int open_pack_bitmap_1(struct packed_git *packfile)
248 {
249         int fd;
250         struct stat st;
251         char *idx_name;
252
253         if (open_pack_index(packfile))
254                 return -1;
255
256         idx_name = pack_bitmap_filename(packfile);
257         fd = git_open_noatime(idx_name);
258         free(idx_name);
259
260         if (fd < 0)
261                 return -1;
262
263         if (fstat(fd, &st)) {
264                 close(fd);
265                 return -1;
266         }
267
268         if (bitmap_git.pack) {
269                 warning("ignoring extra bitmap file: %s", packfile->pack_name);
270                 close(fd);
271                 return -1;
272         }
273
274         bitmap_git.pack = packfile;
275         bitmap_git.map_size = xsize_t(st.st_size);
276         bitmap_git.map = xmmap(NULL, bitmap_git.map_size, PROT_READ, MAP_PRIVATE, fd, 0);
277         bitmap_git.map_pos = 0;
278         close(fd);
279
280         if (load_bitmap_header(&bitmap_git) < 0) {
281                 munmap(bitmap_git.map, bitmap_git.map_size);
282                 bitmap_git.map = NULL;
283                 bitmap_git.map_size = 0;
284                 return -1;
285         }
286
287         return 0;
288 }
289
290 static int load_pack_bitmap(void)
291 {
292         assert(bitmap_git.map && !bitmap_git.loaded);
293
294         bitmap_git.bitmaps = kh_init_sha1();
295         bitmap_git.ext_index.positions = kh_init_sha1_pos();
296         bitmap_git.reverse_index = revindex_for_pack(bitmap_git.pack);
297
298         if (!(bitmap_git.commits = read_bitmap_1(&bitmap_git)) ||
299                 !(bitmap_git.trees = read_bitmap_1(&bitmap_git)) ||
300                 !(bitmap_git.blobs = read_bitmap_1(&bitmap_git)) ||
301                 !(bitmap_git.tags = read_bitmap_1(&bitmap_git)))
302                 goto failed;
303
304         if (load_bitmap_entries_v1(&bitmap_git) < 0)
305                 goto failed;
306
307         bitmap_git.loaded = 1;
308         return 0;
309
310 failed:
311         munmap(bitmap_git.map, bitmap_git.map_size);
312         bitmap_git.map = NULL;
313         bitmap_git.map_size = 0;
314         return -1;
315 }
316
317 char *pack_bitmap_filename(struct packed_git *p)
318 {
319         char *idx_name;
320         int len;
321
322         len = strlen(p->pack_name) - strlen(".pack");
323         idx_name = xmalloc(len + strlen(".bitmap") + 1);
324
325         memcpy(idx_name, p->pack_name, len);
326         memcpy(idx_name + len, ".bitmap", strlen(".bitmap") + 1);
327
328         return idx_name;
329 }
330
331 static int open_pack_bitmap(void)
332 {
333         struct packed_git *p;
334         int ret = -1;
335
336         assert(!bitmap_git.map && !bitmap_git.loaded);
337
338         prepare_packed_git();
339         for (p = packed_git; p; p = p->next) {
340                 if (open_pack_bitmap_1(p) == 0)
341                         ret = 0;
342         }
343
344         return ret;
345 }
346
347 int prepare_bitmap_git(void)
348 {
349         if (bitmap_git.loaded)
350                 return 0;
351
352         if (!open_pack_bitmap())
353                 return load_pack_bitmap();
354
355         return -1;
356 }
357
358 struct include_data {
359         struct bitmap *base;
360         struct bitmap *seen;
361 };
362
363 static inline int bitmap_position_extended(const unsigned char *sha1)
364 {
365         khash_sha1_pos *positions = bitmap_git.ext_index.positions;
366         khiter_t pos = kh_get_sha1_pos(positions, sha1);
367
368         if (pos < kh_end(positions)) {
369                 int bitmap_pos = kh_value(positions, pos);
370                 return bitmap_pos + bitmap_git.pack->num_objects;
371         }
372
373         return -1;
374 }
375
376 static inline int bitmap_position_packfile(const unsigned char *sha1)
377 {
378         off_t offset = find_pack_entry_one(sha1, bitmap_git.pack);
379         if (!offset)
380                 return -1;
381
382         return find_revindex_position(bitmap_git.reverse_index, offset);
383 }
384
385 static int bitmap_position(const unsigned char *sha1)
386 {
387         int pos = bitmap_position_packfile(sha1);
388         return (pos >= 0) ? pos : bitmap_position_extended(sha1);
389 }
390
391 static int ext_index_add_object(struct object *object, const char *name)
392 {
393         struct eindex *eindex = &bitmap_git.ext_index;
394
395         khiter_t hash_pos;
396         int hash_ret;
397         int bitmap_pos;
398
399         hash_pos = kh_put_sha1_pos(eindex->positions, object->sha1, &hash_ret);
400         if (hash_ret > 0) {
401                 if (eindex->count >= eindex->alloc) {
402                         eindex->alloc = (eindex->alloc + 16) * 3 / 2;
403                         REALLOC_ARRAY(eindex->objects, eindex->alloc);
404                         REALLOC_ARRAY(eindex->hashes, eindex->alloc);
405                 }
406
407                 bitmap_pos = eindex->count;
408                 eindex->objects[eindex->count] = object;
409                 eindex->hashes[eindex->count] = pack_name_hash(name);
410                 kh_value(eindex->positions, hash_pos) = bitmap_pos;
411                 eindex->count++;
412         } else {
413                 bitmap_pos = kh_value(eindex->positions, hash_pos);
414         }
415
416         return bitmap_pos + bitmap_git.pack->num_objects;
417 }
418
419 static void show_object(struct object *object, const struct name_path *path,
420                         const char *last, void *data)
421 {
422         struct bitmap *base = data;
423         int bitmap_pos;
424
425         bitmap_pos = bitmap_position(object->sha1);
426
427         if (bitmap_pos < 0) {
428                 char *name = path_name(path, last);
429                 bitmap_pos = ext_index_add_object(object, name);
430                 free(name);
431         }
432
433         bitmap_set(base, bitmap_pos);
434 }
435
436 static void show_commit(struct commit *commit, void *data)
437 {
438 }
439
440 static int add_to_include_set(struct include_data *data,
441                               const unsigned char *sha1,
442                               int bitmap_pos)
443 {
444         khiter_t hash_pos;
445
446         if (data->seen && bitmap_get(data->seen, bitmap_pos))
447                 return 0;
448
449         if (bitmap_get(data->base, bitmap_pos))
450                 return 0;
451
452         hash_pos = kh_get_sha1(bitmap_git.bitmaps, sha1);
453         if (hash_pos < kh_end(bitmap_git.bitmaps)) {
454                 struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, hash_pos);
455                 bitmap_or_ewah(data->base, lookup_stored_bitmap(st));
456                 return 0;
457         }
458
459         bitmap_set(data->base, bitmap_pos);
460         return 1;
461 }
462
463 static int should_include(struct commit *commit, void *_data)
464 {
465         struct include_data *data = _data;
466         int bitmap_pos;
467
468         bitmap_pos = bitmap_position(commit->object.sha1);
469         if (bitmap_pos < 0)
470                 bitmap_pos = ext_index_add_object((struct object *)commit, NULL);
471
472         if (!add_to_include_set(data, commit->object.sha1, bitmap_pos)) {
473                 struct commit_list *parent = commit->parents;
474
475                 while (parent) {
476                         parent->item->object.flags |= SEEN;
477                         parent = parent->next;
478                 }
479
480                 return 0;
481         }
482
483         return 1;
484 }
485
486 static struct bitmap *find_objects(struct rev_info *revs,
487                                    struct object_list *roots,
488                                    struct bitmap *seen)
489 {
490         struct bitmap *base = NULL;
491         int needs_walk = 0;
492
493         struct object_list *not_mapped = NULL;
494
495         /*
496          * Go through all the roots for the walk. The ones that have bitmaps
497          * on the bitmap index will be `or`ed together to form an initial
498          * global reachability analysis.
499          *
500          * The ones without bitmaps in the index will be stored in the
501          * `not_mapped_list` for further processing.
502          */
503         while (roots) {
504                 struct object *object = roots->item;
505                 roots = roots->next;
506
507                 if (object->type == OBJ_COMMIT) {
508                         khiter_t pos = kh_get_sha1(bitmap_git.bitmaps, object->sha1);
509
510                         if (pos < kh_end(bitmap_git.bitmaps)) {
511                                 struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, pos);
512                                 struct ewah_bitmap *or_with = lookup_stored_bitmap(st);
513
514                                 if (base == NULL)
515                                         base = ewah_to_bitmap(or_with);
516                                 else
517                                         bitmap_or_ewah(base, or_with);
518
519                                 object->flags |= SEEN;
520                                 continue;
521                         }
522                 }
523
524                 object_list_insert(object, &not_mapped);
525         }
526
527         /*
528          * Best case scenario: We found bitmaps for all the roots,
529          * so the resulting `or` bitmap has the full reachability analysis
530          */
531         if (not_mapped == NULL)
532                 return base;
533
534         roots = not_mapped;
535
536         /*
537          * Let's iterate through all the roots that don't have bitmaps to
538          * check if we can determine them to be reachable from the existing
539          * global bitmap.
540          *
541          * If we cannot find them in the existing global bitmap, we'll need
542          * to push them to an actual walk and run it until we can confirm
543          * they are reachable
544          */
545         while (roots) {
546                 struct object *object = roots->item;
547                 int pos;
548
549                 roots = roots->next;
550                 pos = bitmap_position(object->sha1);
551
552                 if (pos < 0 || base == NULL || !bitmap_get(base, pos)) {
553                         object->flags &= ~UNINTERESTING;
554                         add_pending_object(revs, object, "");
555                         needs_walk = 1;
556                 } else {
557                         object->flags |= SEEN;
558                 }
559         }
560
561         if (needs_walk) {
562                 struct include_data incdata;
563
564                 if (base == NULL)
565                         base = bitmap_new();
566
567                 incdata.base = base;
568                 incdata.seen = seen;
569
570                 revs->include_check = should_include;
571                 revs->include_check_data = &incdata;
572
573                 if (prepare_revision_walk(revs))
574                         die("revision walk setup failed");
575
576                 traverse_commit_list(revs, show_commit, show_object, base);
577         }
578
579         return base;
580 }
581
582 static void show_extended_objects(struct bitmap *objects,
583                                   show_reachable_fn show_reach)
584 {
585         struct eindex *eindex = &bitmap_git.ext_index;
586         uint32_t i;
587
588         for (i = 0; i < eindex->count; ++i) {
589                 struct object *obj;
590
591                 if (!bitmap_get(objects, bitmap_git.pack->num_objects + i))
592                         continue;
593
594                 obj = eindex->objects[i];
595                 show_reach(obj->sha1, obj->type, 0, eindex->hashes[i], NULL, 0);
596         }
597 }
598
599 static void show_objects_for_type(
600         struct bitmap *objects,
601         struct ewah_bitmap *type_filter,
602         enum object_type object_type,
603         show_reachable_fn show_reach)
604 {
605         size_t pos = 0, i = 0;
606         uint32_t offset;
607
608         struct ewah_iterator it;
609         eword_t filter;
610
611         if (bitmap_git.reuse_objects == bitmap_git.pack->num_objects)
612                 return;
613
614         ewah_iterator_init(&it, type_filter);
615
616         while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) {
617                 eword_t word = objects->words[i] & filter;
618
619                 for (offset = 0; offset < BITS_IN_WORD; ++offset) {
620                         const unsigned char *sha1;
621                         struct revindex_entry *entry;
622                         uint32_t hash = 0;
623
624                         if ((word >> offset) == 0)
625                                 break;
626
627                         offset += ewah_bit_ctz64(word >> offset);
628
629                         if (pos + offset < bitmap_git.reuse_objects)
630                                 continue;
631
632                         entry = &bitmap_git.reverse_index->revindex[pos + offset];
633                         sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
634
635                         if (bitmap_git.hashes)
636                                 hash = ntohl(bitmap_git.hashes[entry->nr]);
637
638                         show_reach(sha1, object_type, 0, hash, bitmap_git.pack, entry->offset);
639                 }
640
641                 pos += BITS_IN_WORD;
642                 i++;
643         }
644 }
645
646 static int in_bitmapped_pack(struct object_list *roots)
647 {
648         while (roots) {
649                 struct object *object = roots->item;
650                 roots = roots->next;
651
652                 if (find_pack_entry_one(object->sha1, bitmap_git.pack) > 0)
653                         return 1;
654         }
655
656         return 0;
657 }
658
659 int prepare_bitmap_walk(struct rev_info *revs)
660 {
661         unsigned int i;
662         unsigned int pending_nr = revs->pending.nr;
663         struct object_array_entry *pending_e = revs->pending.objects;
664
665         struct object_list *wants = NULL;
666         struct object_list *haves = NULL;
667
668         struct bitmap *wants_bitmap = NULL;
669         struct bitmap *haves_bitmap = NULL;
670
671         if (!bitmap_git.loaded) {
672                 /* try to open a bitmapped pack, but don't parse it yet
673                  * because we may not need to use it */
674                 if (open_pack_bitmap() < 0)
675                         return -1;
676         }
677
678         for (i = 0; i < pending_nr; ++i) {
679                 struct object *object = pending_e[i].item;
680
681                 if (object->type == OBJ_NONE)
682                         parse_object_or_die(object->sha1, NULL);
683
684                 while (object->type == OBJ_TAG) {
685                         struct tag *tag = (struct tag *) object;
686
687                         if (object->flags & UNINTERESTING)
688                                 object_list_insert(object, &haves);
689                         else
690                                 object_list_insert(object, &wants);
691
692                         if (!tag->tagged)
693                                 die("bad tag");
694                         object = parse_object_or_die(tag->tagged->sha1, NULL);
695                 }
696
697                 if (object->flags & UNINTERESTING)
698                         object_list_insert(object, &haves);
699                 else
700                         object_list_insert(object, &wants);
701         }
702
703         /*
704          * if we have a HAVES list, but none of those haves is contained
705          * in the packfile that has a bitmap, we don't have anything to
706          * optimize here
707          */
708         if (haves && !in_bitmapped_pack(haves))
709                 return -1;
710
711         /* if we don't want anything, we're done here */
712         if (!wants)
713                 return -1;
714
715         /*
716          * now we're going to use bitmaps, so load the actual bitmap entries
717          * from disk. this is the point of no return; after this the rev_list
718          * becomes invalidated and we must perform the revwalk through bitmaps
719          */
720         if (!bitmap_git.loaded && load_pack_bitmap() < 0)
721                 return -1;
722
723         revs->pending.nr = 0;
724         revs->pending.alloc = 0;
725         revs->pending.objects = NULL;
726
727         if (haves) {
728                 revs->ignore_missing_links = 1;
729                 haves_bitmap = find_objects(revs, haves, NULL);
730                 reset_revision_walk();
731                 revs->ignore_missing_links = 0;
732
733                 if (haves_bitmap == NULL)
734                         die("BUG: failed to perform bitmap walk");
735         }
736
737         wants_bitmap = find_objects(revs, wants, haves_bitmap);
738
739         if (!wants_bitmap)
740                 die("BUG: failed to perform bitmap walk");
741
742         if (haves_bitmap)
743                 bitmap_and_not(wants_bitmap, haves_bitmap);
744
745         bitmap_git.result = wants_bitmap;
746
747         bitmap_free(haves_bitmap);
748         return 0;
749 }
750
751 int reuse_partial_packfile_from_bitmap(struct packed_git **packfile,
752                                        uint32_t *entries,
753                                        off_t *up_to)
754 {
755         /*
756          * Reuse the packfile content if we need more than
757          * 90% of its objects
758          */
759         static const double REUSE_PERCENT = 0.9;
760
761         struct bitmap *result = bitmap_git.result;
762         uint32_t reuse_threshold;
763         uint32_t i, reuse_objects = 0;
764
765         assert(result);
766
767         for (i = 0; i < result->word_alloc; ++i) {
768                 if (result->words[i] != (eword_t)~0) {
769                         reuse_objects += ewah_bit_ctz64(~result->words[i]);
770                         break;
771                 }
772
773                 reuse_objects += BITS_IN_WORD;
774         }
775
776 #ifdef GIT_BITMAP_DEBUG
777         {
778                 const unsigned char *sha1;
779                 struct revindex_entry *entry;
780
781                 entry = &bitmap_git.reverse_index->revindex[reuse_objects];
782                 sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
783
784                 fprintf(stderr, "Failed to reuse at %d (%016llx)\n",
785                         reuse_objects, result->words[i]);
786                 fprintf(stderr, " %s\n", sha1_to_hex(sha1));
787         }
788 #endif
789
790         if (!reuse_objects)
791                 return -1;
792
793         if (reuse_objects >= bitmap_git.pack->num_objects) {
794                 bitmap_git.reuse_objects = *entries = bitmap_git.pack->num_objects;
795                 *up_to = -1; /* reuse the full pack */
796                 *packfile = bitmap_git.pack;
797                 return 0;
798         }
799
800         reuse_threshold = bitmap_popcount(bitmap_git.result) * REUSE_PERCENT;
801
802         if (reuse_objects < reuse_threshold)
803                 return -1;
804
805         bitmap_git.reuse_objects = *entries = reuse_objects;
806         *up_to = bitmap_git.reverse_index->revindex[reuse_objects].offset;
807         *packfile = bitmap_git.pack;
808
809         return 0;
810 }
811
812 void traverse_bitmap_commit_list(show_reachable_fn show_reachable)
813 {
814         assert(bitmap_git.result);
815
816         show_objects_for_type(bitmap_git.result, bitmap_git.commits,
817                 OBJ_COMMIT, show_reachable);
818         show_objects_for_type(bitmap_git.result, bitmap_git.trees,
819                 OBJ_TREE, show_reachable);
820         show_objects_for_type(bitmap_git.result, bitmap_git.blobs,
821                 OBJ_BLOB, show_reachable);
822         show_objects_for_type(bitmap_git.result, bitmap_git.tags,
823                 OBJ_TAG, show_reachable);
824
825         show_extended_objects(bitmap_git.result, show_reachable);
826
827         bitmap_free(bitmap_git.result);
828         bitmap_git.result = NULL;
829 }
830
831 static uint32_t count_object_type(struct bitmap *objects,
832                                   enum object_type type)
833 {
834         struct eindex *eindex = &bitmap_git.ext_index;
835
836         uint32_t i = 0, count = 0;
837         struct ewah_iterator it;
838         eword_t filter;
839
840         switch (type) {
841         case OBJ_COMMIT:
842                 ewah_iterator_init(&it, bitmap_git.commits);
843                 break;
844
845         case OBJ_TREE:
846                 ewah_iterator_init(&it, bitmap_git.trees);
847                 break;
848
849         case OBJ_BLOB:
850                 ewah_iterator_init(&it, bitmap_git.blobs);
851                 break;
852
853         case OBJ_TAG:
854                 ewah_iterator_init(&it, bitmap_git.tags);
855                 break;
856
857         default:
858                 return 0;
859         }
860
861         while (i < objects->word_alloc && ewah_iterator_next(&filter, &it)) {
862                 eword_t word = objects->words[i++] & filter;
863                 count += ewah_bit_popcount64(word);
864         }
865
866         for (i = 0; i < eindex->count; ++i) {
867                 if (eindex->objects[i]->type == type &&
868                         bitmap_get(objects, bitmap_git.pack->num_objects + i))
869                         count++;
870         }
871
872         return count;
873 }
874
875 void count_bitmap_commit_list(uint32_t *commits, uint32_t *trees,
876                               uint32_t *blobs, uint32_t *tags)
877 {
878         assert(bitmap_git.result);
879
880         if (commits)
881                 *commits = count_object_type(bitmap_git.result, OBJ_COMMIT);
882
883         if (trees)
884                 *trees = count_object_type(bitmap_git.result, OBJ_TREE);
885
886         if (blobs)
887                 *blobs = count_object_type(bitmap_git.result, OBJ_BLOB);
888
889         if (tags)
890                 *tags = count_object_type(bitmap_git.result, OBJ_TAG);
891 }
892
893 struct bitmap_test_data {
894         struct bitmap *base;
895         struct progress *prg;
896         size_t seen;
897 };
898
899 static void test_show_object(struct object *object,
900                              const struct name_path *path,
901                              const char *last, void *data)
902 {
903         struct bitmap_test_data *tdata = data;
904         int bitmap_pos;
905
906         bitmap_pos = bitmap_position(object->sha1);
907         if (bitmap_pos < 0)
908                 die("Object not in bitmap: %s\n", sha1_to_hex(object->sha1));
909
910         bitmap_set(tdata->base, bitmap_pos);
911         display_progress(tdata->prg, ++tdata->seen);
912 }
913
914 static void test_show_commit(struct commit *commit, void *data)
915 {
916         struct bitmap_test_data *tdata = data;
917         int bitmap_pos;
918
919         bitmap_pos = bitmap_position(commit->object.sha1);
920         if (bitmap_pos < 0)
921                 die("Object not in bitmap: %s\n", sha1_to_hex(commit->object.sha1));
922
923         bitmap_set(tdata->base, bitmap_pos);
924         display_progress(tdata->prg, ++tdata->seen);
925 }
926
927 void test_bitmap_walk(struct rev_info *revs)
928 {
929         struct object *root;
930         struct bitmap *result = NULL;
931         khiter_t pos;
932         size_t result_popcnt;
933         struct bitmap_test_data tdata;
934
935         if (prepare_bitmap_git())
936                 die("failed to load bitmap indexes");
937
938         if (revs->pending.nr != 1)
939                 die("you must specify exactly one commit to test");
940
941         fprintf(stderr, "Bitmap v%d test (%d entries loaded)\n",
942                 bitmap_git.version, bitmap_git.entry_count);
943
944         root = revs->pending.objects[0].item;
945         pos = kh_get_sha1(bitmap_git.bitmaps, root->sha1);
946
947         if (pos < kh_end(bitmap_git.bitmaps)) {
948                 struct stored_bitmap *st = kh_value(bitmap_git.bitmaps, pos);
949                 struct ewah_bitmap *bm = lookup_stored_bitmap(st);
950
951                 fprintf(stderr, "Found bitmap for %s. %d bits / %08x checksum\n",
952                         sha1_to_hex(root->sha1), (int)bm->bit_size, ewah_checksum(bm));
953
954                 result = ewah_to_bitmap(bm);
955         }
956
957         if (result == NULL)
958                 die("Commit %s doesn't have an indexed bitmap", sha1_to_hex(root->sha1));
959
960         revs->tag_objects = 1;
961         revs->tree_objects = 1;
962         revs->blob_objects = 1;
963
964         result_popcnt = bitmap_popcount(result);
965
966         if (prepare_revision_walk(revs))
967                 die("revision walk setup failed");
968
969         tdata.base = bitmap_new();
970         tdata.prg = start_progress("Verifying bitmap entries", result_popcnt);
971         tdata.seen = 0;
972
973         traverse_commit_list(revs, &test_show_commit, &test_show_object, &tdata);
974
975         stop_progress(&tdata.prg);
976
977         if (bitmap_equals(result, tdata.base))
978                 fprintf(stderr, "OK!\n");
979         else
980                 fprintf(stderr, "Mismatch!\n");
981 }
982
983 static int rebuild_bitmap(uint32_t *reposition,
984                           struct ewah_bitmap *source,
985                           struct bitmap *dest)
986 {
987         uint32_t pos = 0;
988         struct ewah_iterator it;
989         eword_t word;
990
991         ewah_iterator_init(&it, source);
992
993         while (ewah_iterator_next(&word, &it)) {
994                 uint32_t offset, bit_pos;
995
996                 for (offset = 0; offset < BITS_IN_WORD; ++offset) {
997                         if ((word >> offset) == 0)
998                                 break;
999
1000                         offset += ewah_bit_ctz64(word >> offset);
1001
1002                         bit_pos = reposition[pos + offset];
1003                         if (bit_pos > 0)
1004                                 bitmap_set(dest, bit_pos - 1);
1005                         else /* can't reuse, we don't have the object */
1006                                 return -1;
1007                 }
1008
1009                 pos += BITS_IN_WORD;
1010         }
1011         return 0;
1012 }
1013
1014 int rebuild_existing_bitmaps(struct packing_data *mapping,
1015                              khash_sha1 *reused_bitmaps,
1016                              int show_progress)
1017 {
1018         uint32_t i, num_objects;
1019         uint32_t *reposition;
1020         struct bitmap *rebuild;
1021         struct stored_bitmap *stored;
1022         struct progress *progress = NULL;
1023
1024         khiter_t hash_pos;
1025         int hash_ret;
1026
1027         if (prepare_bitmap_git() < 0)
1028                 return -1;
1029
1030         num_objects = bitmap_git.pack->num_objects;
1031         reposition = xcalloc(num_objects, sizeof(uint32_t));
1032
1033         for (i = 0; i < num_objects; ++i) {
1034                 const unsigned char *sha1;
1035                 struct revindex_entry *entry;
1036                 struct object_entry *oe;
1037
1038                 entry = &bitmap_git.reverse_index->revindex[i];
1039                 sha1 = nth_packed_object_sha1(bitmap_git.pack, entry->nr);
1040                 oe = packlist_find(mapping, sha1, NULL);
1041
1042                 if (oe)
1043                         reposition[i] = oe->in_pack_pos + 1;
1044         }
1045
1046         rebuild = bitmap_new();
1047         i = 0;
1048
1049         if (show_progress)
1050                 progress = start_progress("Reusing bitmaps", 0);
1051
1052         kh_foreach_value(bitmap_git.bitmaps, stored, {
1053                 if (stored->flags & BITMAP_FLAG_REUSE) {
1054                         if (!rebuild_bitmap(reposition,
1055                                             lookup_stored_bitmap(stored),
1056                                             rebuild)) {
1057                                 hash_pos = kh_put_sha1(reused_bitmaps,
1058                                                        stored->sha1,
1059                                                        &hash_ret);
1060                                 kh_value(reused_bitmaps, hash_pos) =
1061                                         bitmap_to_ewah(rebuild);
1062                         }
1063                         bitmap_reset(rebuild);
1064                         display_progress(progress, ++i);
1065                 }
1066         });
1067
1068         stop_progress(&progress);
1069
1070         free(reposition);
1071         bitmap_free(rebuild);
1072         return 0;
1073 }