commit-graph.txt: update design document
[git/git.git] / commit-graph.c
CommitLineData
08fd81c9
DS
1#include "cache.h"
2#include "config.h"
3#include "git-compat-util.h"
4#include "lockfile.h"
5#include "pack.h"
6#include "packfile.h"
7#include "commit.h"
8#include "object.h"
9#include "revision.h"
10#include "sha1-lookup.h"
11#include "commit-graph.h"
12
13#define GRAPH_SIGNATURE 0x43475048 /* "CGPH" */
14#define GRAPH_CHUNKID_OIDFANOUT 0x4f494446 /* "OIDF" */
15#define GRAPH_CHUNKID_OIDLOOKUP 0x4f49444c /* "OIDL" */
16#define GRAPH_CHUNKID_DATA 0x43444154 /* "CDAT" */
17#define GRAPH_CHUNKID_LARGEEDGES 0x45444745 /* "EDGE" */
18
19#define GRAPH_DATA_WIDTH 36
20
21#define GRAPH_VERSION_1 0x1
22#define GRAPH_VERSION GRAPH_VERSION_1
23
24#define GRAPH_OID_VERSION_SHA1 1
25#define GRAPH_OID_LEN_SHA1 GIT_SHA1_RAWSZ
26#define GRAPH_OID_VERSION GRAPH_OID_VERSION_SHA1
27#define GRAPH_OID_LEN GRAPH_OID_LEN_SHA1
28
29#define GRAPH_OCTOPUS_EDGES_NEEDED 0x80000000
30#define GRAPH_PARENT_MISSING 0x7fffffff
31#define GRAPH_EDGE_LAST_MASK 0x7fffffff
32#define GRAPH_PARENT_NONE 0x70000000
33
34#define GRAPH_LAST_EDGE 0x80000000
35
36#define GRAPH_FANOUT_SIZE (4 * 256)
37#define GRAPH_CHUNKLOOKUP_WIDTH 12
38#define GRAPH_MIN_SIZE (5 * GRAPH_CHUNKLOOKUP_WIDTH + GRAPH_FANOUT_SIZE + \
39 GRAPH_OID_LEN + 8)
40
2a2e32bd 41char *get_commit_graph_filename(const char *obj_dir)
08fd81c9
DS
42{
43 return xstrfmt("%s/info/commit-graph", obj_dir);
44}
45
2a2e32bd
DS
46static struct commit_graph *alloc_commit_graph(void)
47{
48 struct commit_graph *g = xcalloc(1, sizeof(*g));
49 g->graph_fd = -1;
50
51 return g;
52}
53
54struct commit_graph *load_commit_graph_one(const char *graph_file)
55{
56 void *graph_map;
57 const unsigned char *data, *chunk_lookup;
58 size_t graph_size;
59 struct stat st;
60 uint32_t i;
61 struct commit_graph *graph;
62 int fd = git_open(graph_file);
63 uint64_t last_chunk_offset;
64 uint32_t last_chunk_id;
65 uint32_t graph_signature;
66 unsigned char graph_version, hash_version;
67
68 if (fd < 0)
69 return NULL;
70 if (fstat(fd, &st)) {
71 close(fd);
72 return NULL;
73 }
74 graph_size = xsize_t(st.st_size);
75
76 if (graph_size < GRAPH_MIN_SIZE) {
77 close(fd);
78 die("graph file %s is too small", graph_file);
79 }
80 graph_map = xmmap(NULL, graph_size, PROT_READ, MAP_PRIVATE, fd, 0);
81 data = (const unsigned char *)graph_map;
82
83 graph_signature = get_be32(data);
84 if (graph_signature != GRAPH_SIGNATURE) {
85 error("graph signature %X does not match signature %X",
86 graph_signature, GRAPH_SIGNATURE);
87 goto cleanup_fail;
88 }
89
90 graph_version = *(unsigned char*)(data + 4);
91 if (graph_version != GRAPH_VERSION) {
92 error("graph version %X does not match version %X",
93 graph_version, GRAPH_VERSION);
94 goto cleanup_fail;
95 }
96
97 hash_version = *(unsigned char*)(data + 5);
98 if (hash_version != GRAPH_OID_VERSION) {
99 error("hash version %X does not match version %X",
100 hash_version, GRAPH_OID_VERSION);
101 goto cleanup_fail;
102 }
103
104 graph = alloc_commit_graph();
105
106 graph->hash_len = GRAPH_OID_LEN;
107 graph->num_chunks = *(unsigned char*)(data + 6);
108 graph->graph_fd = fd;
109 graph->data = graph_map;
110 graph->data_len = graph_size;
111
112 last_chunk_id = 0;
113 last_chunk_offset = 8;
114 chunk_lookup = data + 8;
115 for (i = 0; i < graph->num_chunks; i++) {
116 uint32_t chunk_id = get_be32(chunk_lookup + 0);
117 uint64_t chunk_offset = get_be64(chunk_lookup + 4);
118 int chunk_repeated = 0;
119
120 chunk_lookup += GRAPH_CHUNKLOOKUP_WIDTH;
121
122 if (chunk_offset > graph_size - GIT_MAX_RAWSZ) {
123 error("improper chunk offset %08x%08x", (uint32_t)(chunk_offset >> 32),
124 (uint32_t)chunk_offset);
125 goto cleanup_fail;
126 }
127
128 switch (chunk_id) {
129 case GRAPH_CHUNKID_OIDFANOUT:
130 if (graph->chunk_oid_fanout)
131 chunk_repeated = 1;
132 else
133 graph->chunk_oid_fanout = (uint32_t*)(data + chunk_offset);
134 break;
135
136 case GRAPH_CHUNKID_OIDLOOKUP:
137 if (graph->chunk_oid_lookup)
138 chunk_repeated = 1;
139 else
140 graph->chunk_oid_lookup = data + chunk_offset;
141 break;
142
143 case GRAPH_CHUNKID_DATA:
144 if (graph->chunk_commit_data)
145 chunk_repeated = 1;
146 else
147 graph->chunk_commit_data = data + chunk_offset;
148 break;
149
150 case GRAPH_CHUNKID_LARGEEDGES:
151 if (graph->chunk_large_edges)
152 chunk_repeated = 1;
153 else
154 graph->chunk_large_edges = data + chunk_offset;
155 break;
156 }
157
158 if (chunk_repeated) {
159 error("chunk id %08x appears multiple times", chunk_id);
160 goto cleanup_fail;
161 }
162
163 if (last_chunk_id == GRAPH_CHUNKID_OIDLOOKUP)
164 {
165 graph->num_commits = (chunk_offset - last_chunk_offset)
166 / graph->hash_len;
167 }
168
169 last_chunk_id = chunk_id;
170 last_chunk_offset = chunk_offset;
171 }
172
173 return graph;
174
175cleanup_fail:
176 munmap(graph_map, graph_size);
177 close(fd);
178 exit(1);
179}
180
177722b3
DS
181/* global storage */
182static struct commit_graph *commit_graph = NULL;
183
184static void prepare_commit_graph_one(const char *obj_dir)
185{
186 char *graph_name;
187
188 if (commit_graph)
189 return;
190
191 graph_name = get_commit_graph_filename(obj_dir);
192 commit_graph = load_commit_graph_one(graph_name);
193
194 FREE_AND_NULL(graph_name);
195}
196
197static int prepare_commit_graph_run_once = 0;
198static void prepare_commit_graph(void)
199{
200 struct alternate_object_database *alt;
201 char *obj_dir;
202
203 if (prepare_commit_graph_run_once)
204 return;
205 prepare_commit_graph_run_once = 1;
206
207 obj_dir = get_object_directory();
208 prepare_commit_graph_one(obj_dir);
209 prepare_alt_odb();
210 for (alt = alt_odb_list; !commit_graph && alt; alt = alt->next)
211 prepare_commit_graph_one(alt->path);
212}
213
214static void close_commit_graph(void)
215{
216 if (!commit_graph)
217 return;
218
219 if (commit_graph->graph_fd >= 0) {
220 munmap((void *)commit_graph->data, commit_graph->data_len);
221 commit_graph->data = NULL;
222 close(commit_graph->graph_fd);
223 }
224
225 FREE_AND_NULL(commit_graph);
226}
227
228static int bsearch_graph(struct commit_graph *g, struct object_id *oid, uint32_t *pos)
229{
230 return bsearch_hash(oid->hash, g->chunk_oid_fanout,
231 g->chunk_oid_lookup, g->hash_len, pos);
232}
233
234static struct commit_list **insert_parent_or_die(struct commit_graph *g,
235 uint64_t pos,
236 struct commit_list **pptr)
237{
238 struct commit *c;
239 struct object_id oid;
240 hashcpy(oid.hash, g->chunk_oid_lookup + g->hash_len * pos);
241 c = lookup_commit(&oid);
242 if (!c)
243 die("could not find commit %s", oid_to_hex(&oid));
244 c->graph_pos = pos;
245 return &commit_list_insert(c, pptr)->next;
246}
247
e2838d85
DS
248static void fill_commit_graph_info(struct commit *item, struct commit_graph *g, uint32_t pos)
249{
250 const unsigned char *commit_data = g->chunk_commit_data + GRAPH_DATA_WIDTH * pos;
251 item->graph_pos = pos;
252 item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
253}
254
177722b3
DS
255static int fill_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t pos)
256{
177722b3
DS
257 uint32_t edge_value;
258 uint32_t *parent_data_ptr;
259 uint64_t date_low, date_high;
260 struct commit_list **pptr;
261 const unsigned char *commit_data = g->chunk_commit_data + (g->hash_len + 16) * pos;
262
263 item->object.parsed = 1;
264 item->graph_pos = pos;
265
7b8a21db 266 item->maybe_tree = NULL;
177722b3
DS
267
268 date_high = get_be32(commit_data + g->hash_len + 8) & 0x3;
269 date_low = get_be32(commit_data + g->hash_len + 12);
270 item->date = (timestamp_t)((date_high << 32) | date_low);
271
83073cc9
DS
272 item->generation = get_be32(commit_data + g->hash_len + 8) >> 2;
273
177722b3
DS
274 pptr = &item->parents;
275
276 edge_value = get_be32(commit_data + g->hash_len);
277 if (edge_value == GRAPH_PARENT_NONE)
278 return 1;
279 pptr = insert_parent_or_die(g, edge_value, pptr);
280
281 edge_value = get_be32(commit_data + g->hash_len + 4);
282 if (edge_value == GRAPH_PARENT_NONE)
283 return 1;
284 if (!(edge_value & GRAPH_OCTOPUS_EDGES_NEEDED)) {
285 pptr = insert_parent_or_die(g, edge_value, pptr);
286 return 1;
287 }
288
289 parent_data_ptr = (uint32_t*)(g->chunk_large_edges +
290 4 * (uint64_t)(edge_value & GRAPH_EDGE_LAST_MASK));
291 do {
292 edge_value = get_be32(parent_data_ptr);
293 pptr = insert_parent_or_die(g,
294 edge_value & GRAPH_EDGE_LAST_MASK,
295 pptr);
296 parent_data_ptr++;
297 } while (!(edge_value & GRAPH_LAST_EDGE));
298
299 return 1;
300}
301
e2838d85
DS
302static int find_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t *pos)
303{
304 if (item->graph_pos != COMMIT_NOT_FROM_GRAPH) {
305 *pos = item->graph_pos;
306 return 1;
307 } else {
308 return bsearch_graph(g, &(item->object.oid), pos);
309 }
310}
311
177722b3
DS
312int parse_commit_in_graph(struct commit *item)
313{
e2838d85
DS
314 uint32_t pos;
315
177722b3
DS
316 if (!core_commit_graph)
317 return 0;
318 if (item->object.parsed)
319 return 1;
177722b3 320 prepare_commit_graph();
e2838d85
DS
321 if (commit_graph && find_commit_in_graph(item, commit_graph, &pos))
322 return fill_commit_in_graph(item, commit_graph, pos);
177722b3
DS
323 return 0;
324}
325
e2838d85
DS
326void load_commit_graph_info(struct commit *item)
327{
328 uint32_t pos;
329 if (!core_commit_graph)
330 return;
331 prepare_commit_graph();
332 if (commit_graph && find_commit_in_graph(item, commit_graph, &pos))
333 fill_commit_graph_info(item, commit_graph, pos);
334}
335
7b8a21db
DS
336static struct tree *load_tree_for_commit(struct commit_graph *g, struct commit *c)
337{
338 struct object_id oid;
339 const unsigned char *commit_data = g->chunk_commit_data +
340 GRAPH_DATA_WIDTH * (c->graph_pos);
341
342 hashcpy(oid.hash, commit_data);
343 c->maybe_tree = lookup_tree(&oid);
344
345 return c->maybe_tree;
346}
347
348struct tree *get_commit_tree_in_graph(const struct commit *c)
349{
350 if (c->maybe_tree)
351 return c->maybe_tree;
352 if (c->graph_pos == COMMIT_NOT_FROM_GRAPH)
353 BUG("get_commit_tree_in_graph called from non-commit-graph commit");
354
355 return load_tree_for_commit(commit_graph, (struct commit *)c);
356}
357
08fd81c9
DS
358static void write_graph_chunk_fanout(struct hashfile *f,
359 struct commit **commits,
360 int nr_commits)
361{
362 int i, count = 0;
363 struct commit **list = commits;
364
365 /*
366 * Write the first-level table (the list is sorted,
367 * but we use a 256-entry lookup to be able to avoid
368 * having to do eight extra binary search iterations).
369 */
370 for (i = 0; i < 256; i++) {
371 while (count < nr_commits) {
372 if ((*list)->object.oid.hash[0] != i)
373 break;
374 count++;
375 list++;
376 }
377
378 hashwrite_be32(f, count);
379 }
380}
381
382static void write_graph_chunk_oids(struct hashfile *f, int hash_len,
383 struct commit **commits, int nr_commits)
384{
385 struct commit **list = commits;
386 int count;
387 for (count = 0; count < nr_commits; count++, list++)
388 hashwrite(f, (*list)->object.oid.hash, (int)hash_len);
389}
390
391static const unsigned char *commit_to_sha1(size_t index, void *table)
392{
393 struct commit **commits = table;
394 return commits[index]->object.oid.hash;
395}
396
397static void write_graph_chunk_data(struct hashfile *f, int hash_len,
398 struct commit **commits, int nr_commits)
399{
400 struct commit **list = commits;
401 struct commit **last = commits + nr_commits;
402 uint32_t num_extra_edges = 0;
403
404 while (list < last) {
405 struct commit_list *parent;
406 int edge_value;
407 uint32_t packedDate[2];
408
409 parse_commit(*list);
2e27bd77 410 hashwrite(f, get_commit_tree_oid(*list)->hash, hash_len);
08fd81c9
DS
411
412 parent = (*list)->parents;
413
414 if (!parent)
415 edge_value = GRAPH_PARENT_NONE;
416 else {
417 edge_value = sha1_pos(parent->item->object.oid.hash,
418 commits,
419 nr_commits,
420 commit_to_sha1);
421
422 if (edge_value < 0)
423 edge_value = GRAPH_PARENT_MISSING;
424 }
425
426 hashwrite_be32(f, edge_value);
427
428 if (parent)
429 parent = parent->next;
430
431 if (!parent)
432 edge_value = GRAPH_PARENT_NONE;
433 else if (parent->next)
434 edge_value = GRAPH_OCTOPUS_EDGES_NEEDED | num_extra_edges;
435 else {
436 edge_value = sha1_pos(parent->item->object.oid.hash,
437 commits,
438 nr_commits,
439 commit_to_sha1);
440 if (edge_value < 0)
441 edge_value = GRAPH_PARENT_MISSING;
442 }
443
444 hashwrite_be32(f, edge_value);
445
446 if (edge_value & GRAPH_OCTOPUS_EDGES_NEEDED) {
447 do {
448 num_extra_edges++;
449 parent = parent->next;
450 } while (parent);
451 }
452
453 if (sizeof((*list)->date) > 4)
454 packedDate[0] = htonl(((*list)->date >> 32) & 0x3);
455 else
456 packedDate[0] = 0;
457
3258c663
DS
458 packedDate[0] |= htonl((*list)->generation << 2);
459
08fd81c9
DS
460 packedDate[1] = htonl((*list)->date);
461 hashwrite(f, packedDate, 8);
462
463 list++;
464 }
465}
466
467static void write_graph_chunk_large_edges(struct hashfile *f,
468 struct commit **commits,
469 int nr_commits)
470{
471 struct commit **list = commits;
472 struct commit **last = commits + nr_commits;
473 struct commit_list *parent;
474
475 while (list < last) {
476 int num_parents = 0;
477 for (parent = (*list)->parents; num_parents < 3 && parent;
478 parent = parent->next)
479 num_parents++;
480
481 if (num_parents <= 2) {
482 list++;
483 continue;
484 }
485
486 /* Since num_parents > 2, this initializer is safe. */
487 for (parent = (*list)->parents->next; parent; parent = parent->next) {
488 int edge_value = sha1_pos(parent->item->object.oid.hash,
489 commits,
490 nr_commits,
491 commit_to_sha1);
492
493 if (edge_value < 0)
494 edge_value = GRAPH_PARENT_MISSING;
495 else if (!parent->next)
496 edge_value |= GRAPH_LAST_EDGE;
497
498 hashwrite_be32(f, edge_value);
499 }
500
501 list++;
502 }
503}
504
505static int commit_compare(const void *_a, const void *_b)
506{
507 const struct object_id *a = (const struct object_id *)_a;
508 const struct object_id *b = (const struct object_id *)_b;
509 return oidcmp(a, b);
510}
511
512struct packed_commit_list {
513 struct commit **list;
514 int nr;
515 int alloc;
516};
517
518struct packed_oid_list {
519 struct object_id *list;
520 int nr;
521 int alloc;
522};
523
524static int add_packed_commits(const struct object_id *oid,
525 struct packed_git *pack,
526 uint32_t pos,
527 void *data)
528{
529 struct packed_oid_list *list = (struct packed_oid_list*)data;
530 enum object_type type;
531 off_t offset = nth_packed_object_offset(pack, pos);
532 struct object_info oi = OBJECT_INFO_INIT;
533
534 oi.typep = &type;
535 if (packed_object_info(pack, offset, &oi) < 0)
536 die("unable to get type of object %s", oid_to_hex(oid));
537
538 if (type != OBJ_COMMIT)
539 return 0;
540
541 ALLOC_GROW(list->list, list->nr + 1, list->alloc);
542 oidcpy(&(list->list[list->nr]), oid);
543 list->nr++;
544
545 return 0;
546}
547
4f2542b4
DS
548static void add_missing_parents(struct packed_oid_list *oids, struct commit *commit)
549{
550 struct commit_list *parent;
551 for (parent = commit->parents; parent; parent = parent->next) {
552 if (!(parent->item->object.flags & UNINTERESTING)) {
553 ALLOC_GROW(oids->list, oids->nr + 1, oids->alloc);
554 oidcpy(&oids->list[oids->nr], &(parent->item->object.oid));
555 oids->nr++;
556 parent->item->object.flags |= UNINTERESTING;
557 }
558 }
559}
560
561static void close_reachable(struct packed_oid_list *oids)
562{
563 int i;
564 struct commit *commit;
565
566 for (i = 0; i < oids->nr; i++) {
567 commit = lookup_commit(&oids->list[i]);
568 if (commit)
569 commit->object.flags |= UNINTERESTING;
570 }
571
572 /*
573 * As this loop runs, oids->nr may grow, but not more
574 * than the number of missing commits in the reachable
575 * closure.
576 */
577 for (i = 0; i < oids->nr; i++) {
578 commit = lookup_commit(&oids->list[i]);
579
580 if (commit && !parse_commit(commit))
581 add_missing_parents(oids, commit);
582 }
583
584 for (i = 0; i < oids->nr; i++) {
585 commit = lookup_commit(&oids->list[i]);
586
587 if (commit)
588 commit->object.flags &= ~UNINTERESTING;
589 }
590}
591
3258c663
DS
592static void compute_generation_numbers(struct packed_commit_list* commits)
593{
594 int i;
595 struct commit_list *list = NULL;
596
597 for (i = 0; i < commits->nr; i++) {
598 if (commits->list[i]->generation != GENERATION_NUMBER_INFINITY &&
599 commits->list[i]->generation != GENERATION_NUMBER_ZERO)
600 continue;
601
602 commit_list_insert(commits->list[i], &list);
603 while (list) {
604 struct commit *current = list->item;
605 struct commit_list *parent;
606 int all_parents_computed = 1;
607 uint32_t max_generation = 0;
608
609 for (parent = current->parents; parent; parent = parent->next) {
610 if (parent->item->generation == GENERATION_NUMBER_INFINITY ||
611 parent->item->generation == GENERATION_NUMBER_ZERO) {
612 all_parents_computed = 0;
613 commit_list_insert(parent->item, &list);
614 break;
615 } else if (parent->item->generation > max_generation) {
616 max_generation = parent->item->generation;
617 }
618 }
619
620 if (all_parents_computed) {
621 current->generation = max_generation + 1;
622 pop_commit(&list);
623
624 if (current->generation > GENERATION_NUMBER_MAX)
625 current->generation = GENERATION_NUMBER_MAX;
626 }
627 }
628 }
629}
630
049d51a2
DS
631void write_commit_graph(const char *obj_dir,
632 const char **pack_indexes,
3d5df01b
DS
633 int nr_packs,
634 const char **commit_hex,
7547b95b
DS
635 int nr_commits,
636 int append)
08fd81c9
DS
637{
638 struct packed_oid_list oids;
639 struct packed_commit_list commits;
640 struct hashfile *f;
641 uint32_t i, count_distinct = 0;
642 char *graph_name;
643 int fd;
644 struct lock_file lk = LOCK_INIT;
645 uint32_t chunk_ids[5];
646 uint64_t chunk_offsets[5];
647 int num_chunks;
648 int num_extra_edges;
649 struct commit_list *parent;
650
651 oids.nr = 0;
652 oids.alloc = approximate_object_count() / 4;
653
7547b95b
DS
654 if (append) {
655 prepare_commit_graph_one(obj_dir);
656 if (commit_graph)
657 oids.alloc += commit_graph->num_commits;
658 }
659
08fd81c9
DS
660 if (oids.alloc < 1024)
661 oids.alloc = 1024;
662 ALLOC_ARRAY(oids.list, oids.alloc);
663
7547b95b
DS
664 if (append && commit_graph) {
665 for (i = 0; i < commit_graph->num_commits; i++) {
666 const unsigned char *hash = commit_graph->chunk_oid_lookup +
667 commit_graph->hash_len * i;
668 hashcpy(oids.list[oids.nr++].hash, hash);
669 }
670 }
671
049d51a2
DS
672 if (pack_indexes) {
673 struct strbuf packname = STRBUF_INIT;
674 int dirlen;
675 strbuf_addf(&packname, "%s/pack/", obj_dir);
676 dirlen = packname.len;
677 for (i = 0; i < nr_packs; i++) {
678 struct packed_git *p;
679 strbuf_setlen(&packname, dirlen);
680 strbuf_addstr(&packname, pack_indexes[i]);
681 p = add_packed_git(packname.buf, packname.len, 1);
682 if (!p)
683 die("error adding pack %s", packname.buf);
684 if (open_pack_index(p))
685 die("error opening index for %s", packname.buf);
686 for_each_object_in_pack(p, add_packed_commits, &oids);
687 close_pack(p);
688 }
689 strbuf_release(&packname);
3d5df01b
DS
690 }
691
692 if (commit_hex) {
693 for (i = 0; i < nr_commits; i++) {
694 const char *end;
695 struct object_id oid;
696 struct commit *result;
697
698 if (commit_hex[i] && parse_oid_hex(commit_hex[i], &oid, &end))
699 continue;
700
701 result = lookup_commit_reference_gently(&oid, 1);
702
703 if (result) {
704 ALLOC_GROW(oids.list, oids.nr + 1, oids.alloc);
705 oidcpy(&oids.list[oids.nr], &(result->object.oid));
706 oids.nr++;
707 }
708 }
709 }
710
711 if (!pack_indexes && !commit_hex)
049d51a2
DS
712 for_each_packed_object(add_packed_commits, &oids, 0);
713
4f2542b4 714 close_reachable(&oids);
08fd81c9
DS
715
716 QSORT(oids.list, oids.nr, commit_compare);
717
718 count_distinct = 1;
719 for (i = 1; i < oids.nr; i++) {
720 if (oidcmp(&oids.list[i-1], &oids.list[i]))
721 count_distinct++;
722 }
723
724 if (count_distinct >= GRAPH_PARENT_MISSING)
725 die(_("the commit graph format cannot write %d commits"), count_distinct);
726
727 commits.nr = 0;
728 commits.alloc = count_distinct;
729 ALLOC_ARRAY(commits.list, commits.alloc);
730
731 num_extra_edges = 0;
732 for (i = 0; i < oids.nr; i++) {
733 int num_parents = 0;
734 if (i > 0 && !oidcmp(&oids.list[i-1], &oids.list[i]))
735 continue;
736
737 commits.list[commits.nr] = lookup_commit(&oids.list[i]);
738 parse_commit(commits.list[commits.nr]);
739
740 for (parent = commits.list[commits.nr]->parents;
741 parent; parent = parent->next)
742 num_parents++;
743
744 if (num_parents > 2)
745 num_extra_edges += num_parents - 1;
746
747 commits.nr++;
748 }
749 num_chunks = num_extra_edges ? 4 : 3;
750
751 if (commits.nr >= GRAPH_PARENT_MISSING)
752 die(_("too many commits to write graph"));
753
3258c663
DS
754 compute_generation_numbers(&commits);
755
08fd81c9
DS
756 graph_name = get_commit_graph_filename(obj_dir);
757 fd = hold_lock_file_for_update(&lk, graph_name, 0);
758
759 if (fd < 0) {
760 struct strbuf folder = STRBUF_INIT;
761 strbuf_addstr(&folder, graph_name);
762 strbuf_setlen(&folder, strrchr(folder.buf, '/') - folder.buf);
763
764 if (mkdir(folder.buf, 0777) < 0)
765 die_errno(_("cannot mkdir %s"), folder.buf);
766 strbuf_release(&folder);
767
768 fd = hold_lock_file_for_update(&lk, graph_name, LOCK_DIE_ON_ERROR);
769
770 if (fd < 0)
771 die_errno("unable to create '%s'", graph_name);
772 }
773
774 f = hashfd(lk.tempfile->fd, lk.tempfile->filename.buf);
775
776 hashwrite_be32(f, GRAPH_SIGNATURE);
777
778 hashwrite_u8(f, GRAPH_VERSION);
779 hashwrite_u8(f, GRAPH_OID_VERSION);
780 hashwrite_u8(f, num_chunks);
781 hashwrite_u8(f, 0); /* unused padding byte */
782
783 chunk_ids[0] = GRAPH_CHUNKID_OIDFANOUT;
784 chunk_ids[1] = GRAPH_CHUNKID_OIDLOOKUP;
785 chunk_ids[2] = GRAPH_CHUNKID_DATA;
786 if (num_extra_edges)
787 chunk_ids[3] = GRAPH_CHUNKID_LARGEEDGES;
788 else
789 chunk_ids[3] = 0;
790 chunk_ids[4] = 0;
791
792 chunk_offsets[0] = 8 + (num_chunks + 1) * GRAPH_CHUNKLOOKUP_WIDTH;
793 chunk_offsets[1] = chunk_offsets[0] + GRAPH_FANOUT_SIZE;
794 chunk_offsets[2] = chunk_offsets[1] + GRAPH_OID_LEN * commits.nr;
795 chunk_offsets[3] = chunk_offsets[2] + (GRAPH_OID_LEN + 16) * commits.nr;
796 chunk_offsets[4] = chunk_offsets[3] + 4 * num_extra_edges;
797
798 for (i = 0; i <= num_chunks; i++) {
799 uint32_t chunk_write[3];
800
801 chunk_write[0] = htonl(chunk_ids[i]);
802 chunk_write[1] = htonl(chunk_offsets[i] >> 32);
803 chunk_write[2] = htonl(chunk_offsets[i] & 0xffffffff);
804 hashwrite(f, chunk_write, 12);
805 }
806
807 write_graph_chunk_fanout(f, commits.list, commits.nr);
808 write_graph_chunk_oids(f, GRAPH_OID_LEN, commits.list, commits.nr);
809 write_graph_chunk_data(f, GRAPH_OID_LEN, commits.list, commits.nr);
810 write_graph_chunk_large_edges(f, commits.list, commits.nr);
811
177722b3 812 close_commit_graph();
08fd81c9
DS
813 finalize_hashfile(f, NULL, CSUM_HASH_IN_STREAM | CSUM_FSYNC);
814 commit_lock_file(&lk);
815
816 free(oids.list);
817 oids.alloc = 0;
818 oids.nr = 0;
819}