pack-objects: a bit of document about struct object_entry
[git/git.git] / pack-bitmap-write.c
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1#include "cache.h"
2#include "commit.h"
3#include "tag.h"
4#include "diff.h"
5#include "revision.h"
6#include "list-objects.h"
7#include "progress.h"
8#include "pack-revindex.h"
9#include "pack.h"
10#include "pack-bitmap.h"
11#include "sha1-lookup.h"
12#include "pack-objects.h"
13
14struct bitmapped_commit {
15 struct commit *commit;
16 struct ewah_bitmap *bitmap;
17 struct ewah_bitmap *write_as;
18 int flags;
19 int xor_offset;
20 uint32_t commit_pos;
21};
22
23struct bitmap_writer {
24 struct ewah_bitmap *commits;
25 struct ewah_bitmap *trees;
26 struct ewah_bitmap *blobs;
27 struct ewah_bitmap *tags;
28
29 khash_sha1 *bitmaps;
30 khash_sha1 *reused;
31 struct packing_data *to_pack;
32
33 struct bitmapped_commit *selected;
34 unsigned int selected_nr, selected_alloc;
35
36 struct progress *progress;
37 int show_progress;
38 unsigned char pack_checksum[20];
39};
40
41static struct bitmap_writer writer;
42
43void bitmap_writer_show_progress(int show)
44{
45 writer.show_progress = show;
46}
47
48/**
49 * Build the initial type index for the packfile
50 */
51void bitmap_writer_build_type_index(struct pack_idx_entry **index,
52 uint32_t index_nr)
53{
54 uint32_t i;
55
56 writer.commits = ewah_new();
57 writer.trees = ewah_new();
58 writer.blobs = ewah_new();
59 writer.tags = ewah_new();
60
61 for (i = 0; i < index_nr; ++i) {
62 struct object_entry *entry = (struct object_entry *)index[i];
63 enum object_type real_type;
64
65 entry->in_pack_pos = i;
66
67 switch (entry->type) {
68 case OBJ_COMMIT:
69 case OBJ_TREE:
70 case OBJ_BLOB:
71 case OBJ_TAG:
72 real_type = entry->type;
73 break;
74
75 default:
abef9020 76 real_type = oid_object_info(&entry->idx.oid, NULL);
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77 break;
78 }
79
80 switch (real_type) {
81 case OBJ_COMMIT:
82 ewah_set(writer.commits, i);
83 break;
84
85 case OBJ_TREE:
86 ewah_set(writer.trees, i);
87 break;
88
89 case OBJ_BLOB:
90 ewah_set(writer.blobs, i);
91 break;
92
93 case OBJ_TAG:
94 ewah_set(writer.tags, i);
95 break;
96
97 default:
98 die("Missing type information for %s (%d/%d)",
e6a492b7 99 oid_to_hex(&entry->idx.oid), real_type,
100 entry->type);
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101 }
102 }
103}
104
105/**
106 * Compute the actual bitmaps
107 */
108static struct object **seen_objects;
109static unsigned int seen_objects_nr, seen_objects_alloc;
110
111static inline void push_bitmapped_commit(struct commit *commit, struct ewah_bitmap *reused)
112{
113 if (writer.selected_nr >= writer.selected_alloc) {
114 writer.selected_alloc = (writer.selected_alloc + 32) * 2;
2756ca43 115 REALLOC_ARRAY(writer.selected, writer.selected_alloc);
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116 }
117
118 writer.selected[writer.selected_nr].commit = commit;
119 writer.selected[writer.selected_nr].bitmap = reused;
120 writer.selected[writer.selected_nr].flags = 0;
121
122 writer.selected_nr++;
123}
124
125static inline void mark_as_seen(struct object *object)
126{
127 ALLOC_GROW(seen_objects, seen_objects_nr + 1, seen_objects_alloc);
128 seen_objects[seen_objects_nr++] = object;
129}
130
131static inline void reset_all_seen(void)
132{
133 unsigned int i;
134 for (i = 0; i < seen_objects_nr; ++i) {
135 seen_objects[i]->flags &= ~(SEEN | ADDED | SHOWN);
136 }
137 seen_objects_nr = 0;
138}
139
140static uint32_t find_object_pos(const unsigned char *sha1)
141{
142 struct object_entry *entry = packlist_find(writer.to_pack, sha1, NULL);
143
144 if (!entry) {
145 die("Failed to write bitmap index. Packfile doesn't have full closure "
146 "(object %s is missing)", sha1_to_hex(sha1));
147 }
148
149 return entry->in_pack_pos;
150}
151
de1e67d0 152static void show_object(struct object *object, const char *name, void *data)
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153{
154 struct bitmap *base = data;
ed1c9977 155 bitmap_set(base, find_object_pos(object->oid.hash));
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156 mark_as_seen(object);
157}
158
159static void show_commit(struct commit *commit, void *data)
160{
161 mark_as_seen((struct object *)commit);
162}
163
164static int
165add_to_include_set(struct bitmap *base, struct commit *commit)
166{
167 khiter_t hash_pos;
ed1c9977 168 uint32_t bitmap_pos = find_object_pos(commit->object.oid.hash);
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169
170 if (bitmap_get(base, bitmap_pos))
171 return 0;
172
ed1c9977 173 hash_pos = kh_get_sha1(writer.bitmaps, commit->object.oid.hash);
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174 if (hash_pos < kh_end(writer.bitmaps)) {
175 struct bitmapped_commit *bc = kh_value(writer.bitmaps, hash_pos);
176 bitmap_or_ewah(base, bc->bitmap);
177 return 0;
178 }
179
180 bitmap_set(base, bitmap_pos);
181 return 1;
182}
183
184static int
185should_include(struct commit *commit, void *_data)
186{
187 struct bitmap *base = _data;
188
189 if (!add_to_include_set(base, commit)) {
190 struct commit_list *parent = commit->parents;
191
192 mark_as_seen((struct object *)commit);
193
194 while (parent) {
195 parent->item->object.flags |= SEEN;
196 mark_as_seen((struct object *)parent->item);
197 parent = parent->next;
198 }
199
200 return 0;
201 }
202
203 return 1;
204}
205
206static void compute_xor_offsets(void)
207{
208 static const int MAX_XOR_OFFSET_SEARCH = 10;
209
210 int i, next = 0;
211
212 while (next < writer.selected_nr) {
213 struct bitmapped_commit *stored = &writer.selected[next];
214
215 int best_offset = 0;
216 struct ewah_bitmap *best_bitmap = stored->bitmap;
217 struct ewah_bitmap *test_xor;
218
219 for (i = 1; i <= MAX_XOR_OFFSET_SEARCH; ++i) {
220 int curr = next - i;
221
222 if (curr < 0)
223 break;
224
225 test_xor = ewah_pool_new();
226 ewah_xor(writer.selected[curr].bitmap, stored->bitmap, test_xor);
227
228 if (test_xor->buffer_size < best_bitmap->buffer_size) {
229 if (best_bitmap != stored->bitmap)
230 ewah_pool_free(best_bitmap);
231
232 best_bitmap = test_xor;
233 best_offset = i;
234 } else {
235 ewah_pool_free(test_xor);
236 }
237 }
238
239 stored->xor_offset = best_offset;
240 stored->write_as = best_bitmap;
241
242 next++;
243 }
244}
245
246void bitmap_writer_build(struct packing_data *to_pack)
247{
248 static const double REUSE_BITMAP_THRESHOLD = 0.2;
249
250 int i, reuse_after, need_reset;
251 struct bitmap *base = bitmap_new();
252 struct rev_info revs;
253
254 writer.bitmaps = kh_init_sha1();
255 writer.to_pack = to_pack;
256
257 if (writer.show_progress)
258 writer.progress = start_progress("Building bitmaps", writer.selected_nr);
259
260 init_revisions(&revs, NULL);
261 revs.tag_objects = 1;
262 revs.tree_objects = 1;
263 revs.blob_objects = 1;
264 revs.no_walk = 0;
265
266 revs.include_check = should_include;
267 reset_revision_walk();
268
269 reuse_after = writer.selected_nr * REUSE_BITMAP_THRESHOLD;
270 need_reset = 0;
271
272 for (i = writer.selected_nr - 1; i >= 0; --i) {
273 struct bitmapped_commit *stored;
274 struct object *object;
275
276 khiter_t hash_pos;
277 int hash_ret;
278
279 stored = &writer.selected[i];
280 object = (struct object *)stored->commit;
281
282 if (stored->bitmap == NULL) {
283 if (i < writer.selected_nr - 1 &&
284 (need_reset ||
285 !in_merge_bases(writer.selected[i + 1].commit,
286 stored->commit))) {
287 bitmap_reset(base);
288 reset_all_seen();
289 }
290
291 add_pending_object(&revs, object, "");
292 revs.include_check_data = base;
293
294 if (prepare_revision_walk(&revs))
295 die("revision walk setup failed");
296
297 traverse_commit_list(&revs, show_commit, show_object, base);
298
4d01a7fa 299 object_array_clear(&revs.pending);
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300
301 stored->bitmap = bitmap_to_ewah(base);
302 need_reset = 0;
303 } else
304 need_reset = 1;
305
306 if (i >= reuse_after)
307 stored->flags |= BITMAP_FLAG_REUSE;
308
ed1c9977 309 hash_pos = kh_put_sha1(writer.bitmaps, object->oid.hash, &hash_ret);
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310 if (hash_ret == 0)
311 die("Duplicate entry when writing index: %s",
f2fd0760 312 oid_to_hex(&object->oid));
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313
314 kh_value(writer.bitmaps, hash_pos) = stored;
315 display_progress(writer.progress, writer.selected_nr - i);
316 }
317
318 bitmap_free(base);
319 stop_progress(&writer.progress);
320
321 compute_xor_offsets();
322}
323
324/**
325 * Select the commits that will be bitmapped
326 */
327static inline unsigned int next_commit_index(unsigned int idx)
328{
329 static const unsigned int MIN_COMMITS = 100;
330 static const unsigned int MAX_COMMITS = 5000;
331
332 static const unsigned int MUST_REGION = 100;
333 static const unsigned int MIN_REGION = 20000;
334
335 unsigned int offset, next;
336
337 if (idx <= MUST_REGION)
338 return 0;
339
340 if (idx <= MIN_REGION) {
341 offset = idx - MUST_REGION;
342 return (offset < MIN_COMMITS) ? offset : MIN_COMMITS;
343 }
344
345 offset = idx - MIN_REGION;
346 next = (offset < MAX_COMMITS) ? offset : MAX_COMMITS;
347
348 return (next > MIN_COMMITS) ? next : MIN_COMMITS;
349}
350
351static int date_compare(const void *_a, const void *_b)
352{
353 struct commit *a = *(struct commit **)_a;
354 struct commit *b = *(struct commit **)_b;
355 return (long)b->date - (long)a->date;
356}
357
358void bitmap_writer_reuse_bitmaps(struct packing_data *to_pack)
359{
360 if (prepare_bitmap_git() < 0)
361 return;
362
363 writer.reused = kh_init_sha1();
364 rebuild_existing_bitmaps(to_pack, writer.reused, writer.show_progress);
365}
366
367static struct ewah_bitmap *find_reused_bitmap(const unsigned char *sha1)
368{
369 khiter_t hash_pos;
370
371 if (!writer.reused)
372 return NULL;
373
374 hash_pos = kh_get_sha1(writer.reused, sha1);
375 if (hash_pos >= kh_end(writer.reused))
376 return NULL;
377
378 return kh_value(writer.reused, hash_pos);
379}
380
381void bitmap_writer_select_commits(struct commit **indexed_commits,
382 unsigned int indexed_commits_nr,
383 int max_bitmaps)
384{
385 unsigned int i = 0, j, next;
386
9ed0d8d6 387 QSORT(indexed_commits, indexed_commits_nr, date_compare);
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388
389 if (writer.show_progress)
390 writer.progress = start_progress("Selecting bitmap commits", 0);
391
392 if (indexed_commits_nr < 100) {
393 for (i = 0; i < indexed_commits_nr; ++i)
394 push_bitmapped_commit(indexed_commits[i], NULL);
395 return;
396 }
397
398 for (;;) {
399 struct ewah_bitmap *reused_bitmap = NULL;
400 struct commit *chosen = NULL;
401
402 next = next_commit_index(i);
403
404 if (i + next >= indexed_commits_nr)
405 break;
406
407 if (max_bitmaps > 0 && writer.selected_nr >= max_bitmaps) {
408 writer.selected_nr = max_bitmaps;
409 break;
410 }
411
412 if (next == 0) {
413 chosen = indexed_commits[i];
ed1c9977 414 reused_bitmap = find_reused_bitmap(chosen->object.oid.hash);
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415 } else {
416 chosen = indexed_commits[i + next];
417
418 for (j = 0; j <= next; ++j) {
419 struct commit *cm = indexed_commits[i + j];
420
ed1c9977 421 reused_bitmap = find_reused_bitmap(cm->object.oid.hash);
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422 if (reused_bitmap || (cm->object.flags & NEEDS_BITMAP) != 0) {
423 chosen = cm;
424 break;
425 }
426
427 if (cm->parents && cm->parents->next)
428 chosen = cm;
429 }
430 }
431
432 push_bitmapped_commit(chosen, reused_bitmap);
433
434 i += next + 1;
435 display_progress(writer.progress, i);
436 }
437
438 stop_progress(&writer.progress);
439}
440
441
98a3beab 442static int hashwrite_ewah_helper(void *f, const void *buf, size_t len)
7cc8f971 443{
98a3beab 444 /* hashwrite will die on error */
445 hashwrite(f, buf, len);
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446 return len;
447}
448
449/**
450 * Write the bitmap index to disk
451 */
98a3beab 452static inline void dump_bitmap(struct hashfile *f, struct ewah_bitmap *bitmap)
7cc8f971 453{
98a3beab 454 if (ewah_serialize_to(bitmap, hashwrite_ewah_helper, f) < 0)
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455 die("Failed to write bitmap index");
456}
457
458static const unsigned char *sha1_access(size_t pos, void *table)
459{
460 struct pack_idx_entry **index = table;
e6a492b7 461 return index[pos]->oid.hash;
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462}
463
98a3beab 464static void write_selected_commits_v1(struct hashfile *f,
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465 struct pack_idx_entry **index,
466 uint32_t index_nr)
467{
468 int i;
469
470 for (i = 0; i < writer.selected_nr; ++i) {
471 struct bitmapped_commit *stored = &writer.selected[i];
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472
473 int commit_pos =
ed1c9977 474 sha1_pos(stored->commit->object.oid.hash, index, index_nr, sha1_access);
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475
476 if (commit_pos < 0)
477 die("BUG: trying to write commit not in index");
478
98a3beab 479 hashwrite_be32(f, commit_pos);
480 hashwrite_u8(f, stored->xor_offset);
481 hashwrite_u8(f, stored->flags);
7cc8f971 482
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483 dump_bitmap(f, stored->write_as);
484 }
485}
486
98a3beab 487static void write_hash_cache(struct hashfile *f,
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488 struct pack_idx_entry **index,
489 uint32_t index_nr)
490{
491 uint32_t i;
492
493 for (i = 0; i < index_nr; ++i) {
494 struct object_entry *entry = (struct object_entry *)index[i];
495 uint32_t hash_value = htonl(entry->hash);
98a3beab 496 hashwrite(f, &hash_value, sizeof(hash_value));
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497 }
498}
499
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500void bitmap_writer_set_checksum(unsigned char *sha1)
501{
502 hashcpy(writer.pack_checksum, sha1);
503}
504
505void bitmap_writer_finish(struct pack_idx_entry **index,
506 uint32_t index_nr,
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507 const char *filename,
508 uint16_t options)
7cc8f971 509{
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510 static uint16_t default_version = 1;
511 static uint16_t flags = BITMAP_OPT_FULL_DAG;
594fa999 512 struct strbuf tmp_file = STRBUF_INIT;
98a3beab 513 struct hashfile *f;
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514
515 struct bitmap_disk_header header;
516
594fa999 517 int fd = odb_mkstemp(&tmp_file, "pack/tmp_bitmap_XXXXXX");
7cc8f971 518
98a3beab 519 f = hashfd(fd, tmp_file.buf);
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520
521 memcpy(header.magic, BITMAP_IDX_SIGNATURE, sizeof(BITMAP_IDX_SIGNATURE));
522 header.version = htons(default_version);
ae4f07fb 523 header.options = htons(flags | options);
7cc8f971 524 header.entry_count = htonl(writer.selected_nr);
50546b15 525 hashcpy(header.checksum, writer.pack_checksum);
7cc8f971 526
98a3beab 527 hashwrite(f, &header, sizeof(header));
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528 dump_bitmap(f, writer.commits);
529 dump_bitmap(f, writer.trees);
530 dump_bitmap(f, writer.blobs);
531 dump_bitmap(f, writer.tags);
532 write_selected_commits_v1(f, index, index_nr);
533
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534 if (options & BITMAP_OPT_HASH_CACHE)
535 write_hash_cache(f, index, index_nr);
536
98a3beab 537 hashclose(f, NULL, CSUM_FSYNC);
7cc8f971 538
594fa999 539 if (adjust_shared_perm(tmp_file.buf))
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540 die_errno("unable to make temporary bitmap file readable");
541
594fa999 542 if (rename(tmp_file.buf, filename))
7cc8f971 543 die_errno("unable to rename temporary bitmap file to '%s'", filename);
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544
545 strbuf_release(&tmp_file);
7cc8f971 546}