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[git] / shallow.c
1 #include "cache.h"
2 #include "commit.h"
3 #include "tag.h"
4 #include "pkt-line.h"
5 #include "remote.h"
6 #include "refs.h"
7 #include "sha1-array.h"
8 #include "diff.h"
9 #include "revision.h"
10 #include "commit-slab.h"
11 #include "sigchain.h"
12
13 static int is_shallow = -1;
14 static struct stat_validity shallow_stat;
15 static char *alternate_shallow_file;
16
17 void set_alternate_shallow_file(const char *path, int override)
18 {
19         if (is_shallow != -1)
20                 die("BUG: is_repository_shallow must not be called before set_alternate_shallow_file");
21         if (alternate_shallow_file && !override)
22                 return;
23         free(alternate_shallow_file);
24         alternate_shallow_file = path ? xstrdup(path) : NULL;
25 }
26
27 int register_shallow(const unsigned char *sha1)
28 {
29         struct commit_graft *graft =
30                 xmalloc(sizeof(struct commit_graft));
31         struct commit *commit = lookup_commit(sha1);
32
33         hashcpy(graft->sha1, sha1);
34         graft->nr_parent = -1;
35         if (commit && commit->object.parsed)
36                 commit->parents = NULL;
37         return register_commit_graft(graft, 0);
38 }
39
40 int is_repository_shallow(void)
41 {
42         FILE *fp;
43         char buf[1024];
44         const char *path = alternate_shallow_file;
45
46         if (is_shallow >= 0)
47                 return is_shallow;
48
49         if (!path)
50                 path = git_path("shallow");
51         /*
52          * fetch-pack sets '--shallow-file ""' as an indicator that no
53          * shallow file should be used. We could just open it and it
54          * will likely fail. But let's do an explicit check instead.
55          */
56         if (!*path || (fp = fopen(path, "r")) == NULL) {
57                 stat_validity_clear(&shallow_stat);
58                 is_shallow = 0;
59                 return is_shallow;
60         }
61         stat_validity_update(&shallow_stat, fileno(fp));
62         is_shallow = 1;
63
64         while (fgets(buf, sizeof(buf), fp)) {
65                 unsigned char sha1[20];
66                 if (get_sha1_hex(buf, sha1))
67                         die("bad shallow line: %s", buf);
68                 register_shallow(sha1);
69         }
70         fclose(fp);
71         return is_shallow;
72 }
73
74 struct commit_list *get_shallow_commits(struct object_array *heads, int depth,
75                 int shallow_flag, int not_shallow_flag)
76 {
77         int i = 0, cur_depth = 0;
78         struct commit_list *result = NULL;
79         struct object_array stack = OBJECT_ARRAY_INIT;
80         struct commit *commit = NULL;
81         struct commit_graft *graft;
82
83         while (commit || i < heads->nr || stack.nr) {
84                 struct commit_list *p;
85                 if (!commit) {
86                         if (i < heads->nr) {
87                                 commit = (struct commit *)
88                                         deref_tag(heads->objects[i++].item, NULL, 0);
89                                 if (!commit || commit->object.type != OBJ_COMMIT) {
90                                         commit = NULL;
91                                         continue;
92                                 }
93                                 if (!commit->util)
94                                         commit->util = xmalloc(sizeof(int));
95                                 *(int *)commit->util = 0;
96                                 cur_depth = 0;
97                         } else {
98                                 commit = (struct commit *)
99                                         stack.objects[--stack.nr].item;
100                                 cur_depth = *(int *)commit->util;
101                         }
102                 }
103                 parse_commit_or_die(commit);
104                 cur_depth++;
105                 if ((depth != INFINITE_DEPTH && cur_depth >= depth) ||
106                     (is_repository_shallow() && !commit->parents &&
107                      (graft = lookup_commit_graft(commit->object.sha1)) != NULL &&
108                      graft->nr_parent < 0)) {
109                         commit_list_insert(commit, &result);
110                         commit->object.flags |= shallow_flag;
111                         commit = NULL;
112                         continue;
113                 }
114                 commit->object.flags |= not_shallow_flag;
115                 for (p = commit->parents, commit = NULL; p; p = p->next) {
116                         if (!p->item->util) {
117                                 int *pointer = xmalloc(sizeof(int));
118                                 p->item->util = pointer;
119                                 *pointer =  cur_depth;
120                         } else {
121                                 int *pointer = p->item->util;
122                                 if (cur_depth >= *pointer)
123                                         continue;
124                                 *pointer = cur_depth;
125                         }
126                         if (p->next)
127                                 add_object_array(&p->item->object,
128                                                 NULL, &stack);
129                         else {
130                                 commit = p->item;
131                                 cur_depth = *(int *)commit->util;
132                         }
133                 }
134         }
135
136         return result;
137 }
138
139 void check_shallow_file_for_update(void)
140 {
141         if (is_shallow == -1)
142                 die("BUG: shallow must be initialized by now");
143
144         if (!stat_validity_check(&shallow_stat, git_path("shallow")))
145                 die("shallow file has changed since we read it");
146 }
147
148 #define SEEN_ONLY 1
149 #define VERBOSE   2
150
151 struct write_shallow_data {
152         struct strbuf *out;
153         int use_pack_protocol;
154         int count;
155         unsigned flags;
156 };
157
158 static int write_one_shallow(const struct commit_graft *graft, void *cb_data)
159 {
160         struct write_shallow_data *data = cb_data;
161         const char *hex = sha1_to_hex(graft->sha1);
162         if (graft->nr_parent != -1)
163                 return 0;
164         if (data->flags & SEEN_ONLY) {
165                 struct commit *c = lookup_commit(graft->sha1);
166                 if (!c || !(c->object.flags & SEEN)) {
167                         if (data->flags & VERBOSE)
168                                 printf("Removing %s from .git/shallow\n",
169                                        sha1_to_hex(c->object.sha1));
170                         return 0;
171                 }
172         }
173         data->count++;
174         if (data->use_pack_protocol)
175                 packet_buf_write(data->out, "shallow %s", hex);
176         else {
177                 strbuf_addstr(data->out, hex);
178                 strbuf_addch(data->out, '\n');
179         }
180         return 0;
181 }
182
183 static int write_shallow_commits_1(struct strbuf *out, int use_pack_protocol,
184                                    const struct sha1_array *extra,
185                                    unsigned flags)
186 {
187         struct write_shallow_data data;
188         int i;
189         data.out = out;
190         data.use_pack_protocol = use_pack_protocol;
191         data.count = 0;
192         data.flags = flags;
193         for_each_commit_graft(write_one_shallow, &data);
194         if (!extra)
195                 return data.count;
196         for (i = 0; i < extra->nr; i++) {
197                 strbuf_addstr(out, sha1_to_hex(extra->sha1[i]));
198                 strbuf_addch(out, '\n');
199                 data.count++;
200         }
201         return data.count;
202 }
203
204 int write_shallow_commits(struct strbuf *out, int use_pack_protocol,
205                           const struct sha1_array *extra)
206 {
207         return write_shallow_commits_1(out, use_pack_protocol, extra, 0);
208 }
209
210 static struct strbuf temporary_shallow = STRBUF_INIT;
211
212 static void remove_temporary_shallow(void)
213 {
214         if (temporary_shallow.len) {
215                 unlink_or_warn(temporary_shallow.buf);
216                 strbuf_reset(&temporary_shallow);
217         }
218 }
219
220 static void remove_temporary_shallow_on_signal(int signo)
221 {
222         remove_temporary_shallow();
223         sigchain_pop(signo);
224         raise(signo);
225 }
226
227 const char *setup_temporary_shallow(const struct sha1_array *extra)
228 {
229         static int installed_handler;
230         struct strbuf sb = STRBUF_INIT;
231         int fd;
232
233         if (temporary_shallow.len)
234                 die("BUG: attempt to create two temporary shallow files");
235
236         if (write_shallow_commits(&sb, 0, extra)) {
237                 strbuf_addstr(&temporary_shallow, git_path("shallow_XXXXXX"));
238                 fd = xmkstemp(temporary_shallow.buf);
239
240                 if (!installed_handler) {
241                         atexit(remove_temporary_shallow);
242                         sigchain_push_common(remove_temporary_shallow_on_signal);
243                 }
244
245                 if (write_in_full(fd, sb.buf, sb.len) != sb.len)
246                         die_errno("failed to write to %s",
247                                   temporary_shallow.buf);
248                 close(fd);
249                 strbuf_release(&sb);
250                 return temporary_shallow.buf;
251         }
252         /*
253          * is_repository_shallow() sees empty string as "no shallow
254          * file".
255          */
256         return temporary_shallow.buf;
257 }
258
259 void setup_alternate_shallow(struct lock_file *shallow_lock,
260                              const char **alternate_shallow_file,
261                              const struct sha1_array *extra)
262 {
263         struct strbuf sb = STRBUF_INIT;
264         int fd;
265
266         fd = hold_lock_file_for_update(shallow_lock, git_path("shallow"),
267                                        LOCK_DIE_ON_ERROR);
268         check_shallow_file_for_update();
269         if (write_shallow_commits(&sb, 0, extra)) {
270                 if (write_in_full(fd, sb.buf, sb.len) != sb.len)
271                         die_errno("failed to write to %s",
272                                   shallow_lock->filename);
273                 *alternate_shallow_file = shallow_lock->filename;
274         } else
275                 /*
276                  * is_repository_shallow() sees empty string as "no
277                  * shallow file".
278                  */
279                 *alternate_shallow_file = "";
280         strbuf_release(&sb);
281 }
282
283 static int advertise_shallow_grafts_cb(const struct commit_graft *graft, void *cb)
284 {
285         int fd = *(int *)cb;
286         if (graft->nr_parent == -1)
287                 packet_write(fd, "shallow %s\n", sha1_to_hex(graft->sha1));
288         return 0;
289 }
290
291 void advertise_shallow_grafts(int fd)
292 {
293         if (!is_repository_shallow())
294                 return;
295         for_each_commit_graft(advertise_shallow_grafts_cb, &fd);
296 }
297
298 /*
299  * mark_reachable_objects() should have been run prior to this and all
300  * reachable commits marked as "SEEN".
301  */
302 void prune_shallow(int show_only)
303 {
304         static struct lock_file shallow_lock;
305         struct strbuf sb = STRBUF_INIT;
306         int fd;
307
308         if (show_only) {
309                 write_shallow_commits_1(&sb, 0, NULL, SEEN_ONLY | VERBOSE);
310                 strbuf_release(&sb);
311                 return;
312         }
313         fd = hold_lock_file_for_update(&shallow_lock, git_path("shallow"),
314                                        LOCK_DIE_ON_ERROR);
315         check_shallow_file_for_update();
316         if (write_shallow_commits_1(&sb, 0, NULL, SEEN_ONLY)) {
317                 if (write_in_full(fd, sb.buf, sb.len) != sb.len)
318                         die_errno("failed to write to %s",
319                                   shallow_lock.filename);
320                 commit_lock_file(&shallow_lock);
321         } else {
322                 unlink(git_path("shallow"));
323                 rollback_lock_file(&shallow_lock);
324         }
325         strbuf_release(&sb);
326 }
327
328 #define TRACE_KEY "GIT_TRACE_SHALLOW"
329
330 /*
331  * Step 1, split sender shallow commits into "ours" and "theirs"
332  * Step 2, clean "ours" based on .git/shallow
333  */
334 void prepare_shallow_info(struct shallow_info *info, struct sha1_array *sa)
335 {
336         int i;
337         trace_printf_key(TRACE_KEY, "shallow: prepare_shallow_info\n");
338         memset(info, 0, sizeof(*info));
339         info->shallow = sa;
340         if (!sa)
341                 return;
342         info->ours = xmalloc(sizeof(*info->ours) * sa->nr);
343         info->theirs = xmalloc(sizeof(*info->theirs) * sa->nr);
344         for (i = 0; i < sa->nr; i++) {
345                 if (has_sha1_file(sa->sha1[i])) {
346                         struct commit_graft *graft;
347                         graft = lookup_commit_graft(sa->sha1[i]);
348                         if (graft && graft->nr_parent < 0)
349                                 continue;
350                         info->ours[info->nr_ours++] = i;
351                 } else
352                         info->theirs[info->nr_theirs++] = i;
353         }
354 }
355
356 void clear_shallow_info(struct shallow_info *info)
357 {
358         free(info->ours);
359         free(info->theirs);
360 }
361
362 /* Step 4, remove non-existent ones in "theirs" after getting the pack */
363
364 void remove_nonexistent_theirs_shallow(struct shallow_info *info)
365 {
366         unsigned char (*sha1)[20] = info->shallow->sha1;
367         int i, dst;
368         trace_printf_key(TRACE_KEY, "shallow: remove_nonexistent_theirs_shallow\n");
369         for (i = dst = 0; i < info->nr_theirs; i++) {
370                 if (i != dst)
371                         info->theirs[dst] = info->theirs[i];
372                 if (has_sha1_file(sha1[info->theirs[i]]))
373                         dst++;
374         }
375         info->nr_theirs = dst;
376 }
377
378 define_commit_slab(ref_bitmap, uint32_t *);
379
380 struct paint_info {
381         struct ref_bitmap ref_bitmap;
382         unsigned nr_bits;
383         char **slab;
384         char *free, *end;
385         unsigned slab_count;
386 };
387
388 static uint32_t *paint_alloc(struct paint_info *info)
389 {
390         unsigned nr = (info->nr_bits + 31) / 32;
391         unsigned size = nr * sizeof(uint32_t);
392         void *p;
393         if (!info->slab_count || info->free + size > info->end) {
394                 info->slab_count++;
395                 info->slab = xrealloc(info->slab,
396                                       info->slab_count * sizeof(*info->slab));
397                 info->free = xmalloc(COMMIT_SLAB_SIZE);
398                 info->slab[info->slab_count - 1] = info->free;
399                 info->end = info->free + COMMIT_SLAB_SIZE;
400         }
401         p = info->free;
402         info->free += size;
403         return p;
404 }
405
406 /*
407  * Given a commit SHA-1, walk down to parents until either SEEN,
408  * UNINTERESTING or BOTTOM is hit. Set the id-th bit in ref_bitmap for
409  * all walked commits.
410  */
411 static void paint_down(struct paint_info *info, const unsigned char *sha1,
412                        int id)
413 {
414         unsigned int i, nr;
415         struct commit_list *head = NULL;
416         int bitmap_nr = (info->nr_bits + 31) / 32;
417         int bitmap_size = bitmap_nr * sizeof(uint32_t);
418         uint32_t *tmp = xmalloc(bitmap_size); /* to be freed before return */
419         uint32_t *bitmap = paint_alloc(info);
420         struct commit *c = lookup_commit_reference_gently(sha1, 1);
421         if (!c)
422                 return;
423         memset(bitmap, 0, bitmap_size);
424         bitmap[id / 32] |= (1 << (id % 32));
425         commit_list_insert(c, &head);
426         while (head) {
427                 struct commit_list *p;
428                 struct commit *c = head->item;
429                 uint32_t **refs = ref_bitmap_at(&info->ref_bitmap, c);
430
431                 p = head;
432                 head = head->next;
433                 free(p);
434
435                 /* XXX check "UNINTERESTING" from pack bitmaps if available */
436                 if (c->object.flags & (SEEN | UNINTERESTING))
437                         continue;
438                 else
439                         c->object.flags |= SEEN;
440
441                 if (*refs == NULL)
442                         *refs = bitmap;
443                 else {
444                         memcpy(tmp, *refs, bitmap_size);
445                         for (i = 0; i < bitmap_nr; i++)
446                                 tmp[i] |= bitmap[i];
447                         if (memcmp(tmp, *refs, bitmap_size)) {
448                                 *refs = paint_alloc(info);
449                                 memcpy(*refs, tmp, bitmap_size);
450                         }
451                 }
452
453                 if (c->object.flags & BOTTOM)
454                         continue;
455
456                 if (parse_commit(c))
457                         die("unable to parse commit %s",
458                             sha1_to_hex(c->object.sha1));
459
460                 for (p = c->parents; p; p = p->next) {
461                         uint32_t **p_refs = ref_bitmap_at(&info->ref_bitmap,
462                                                           p->item);
463                         if (p->item->object.flags & SEEN)
464                                 continue;
465                         if (*p_refs == NULL || *p_refs == *refs)
466                                 *p_refs = *refs;
467                         commit_list_insert(p->item, &head);
468                 }
469         }
470
471         nr = get_max_object_index();
472         for (i = 0; i < nr; i++) {
473                 struct object *o = get_indexed_object(i);
474                 if (o && o->type == OBJ_COMMIT)
475                         o->flags &= ~SEEN;
476         }
477
478         free(tmp);
479 }
480
481 static int mark_uninteresting(const char *refname,
482                               const unsigned char *sha1,
483                               int flags, void *cb_data)
484 {
485         struct commit *commit = lookup_commit_reference_gently(sha1, 1);
486         if (!commit)
487                 return 0;
488         commit->object.flags |= UNINTERESTING;
489         mark_parents_uninteresting(commit);
490         return 0;
491 }
492
493 static void post_assign_shallow(struct shallow_info *info,
494                                 struct ref_bitmap *ref_bitmap,
495                                 int *ref_status);
496 /*
497  * Step 6(+7), associate shallow commits with new refs
498  *
499  * info->ref must be initialized before calling this function.
500  *
501  * If used is not NULL, it's an array of info->shallow->nr
502  * bitmaps. The n-th bit set in the m-th bitmap if ref[n] needs the
503  * m-th shallow commit from info->shallow.
504  *
505  * If used is NULL, "ours" and "theirs" are updated. And if ref_status
506  * is not NULL it's an array of ref->nr ints. ref_status[i] is true if
507  * the ref needs some shallow commits from either info->ours or
508  * info->theirs.
509  */
510 void assign_shallow_commits_to_refs(struct shallow_info *info,
511                                     uint32_t **used, int *ref_status)
512 {
513         unsigned char (*sha1)[20] = info->shallow->sha1;
514         struct sha1_array *ref = info->ref;
515         unsigned int i, nr;
516         int *shallow, nr_shallow = 0;
517         struct paint_info pi;
518
519         trace_printf_key(TRACE_KEY, "shallow: assign_shallow_commits_to_refs\n");
520         shallow = xmalloc(sizeof(*shallow) * (info->nr_ours + info->nr_theirs));
521         for (i = 0; i < info->nr_ours; i++)
522                 shallow[nr_shallow++] = info->ours[i];
523         for (i = 0; i < info->nr_theirs; i++)
524                 shallow[nr_shallow++] = info->theirs[i];
525
526         /*
527          * Prepare the commit graph to track what refs can reach what
528          * (new) shallow commits.
529          */
530         nr = get_max_object_index();
531         for (i = 0; i < nr; i++) {
532                 struct object *o = get_indexed_object(i);
533                 if (!o || o->type != OBJ_COMMIT)
534                         continue;
535
536                 o->flags &= ~(UNINTERESTING | BOTTOM | SEEN);
537         }
538
539         memset(&pi, 0, sizeof(pi));
540         init_ref_bitmap(&pi.ref_bitmap);
541         pi.nr_bits = ref->nr;
542
543         /*
544          * "--not --all" to cut short the traversal if new refs
545          * connect to old refs. If not (e.g. force ref updates) it'll
546          * have to go down to the current shallow commits.
547          */
548         head_ref(mark_uninteresting, NULL);
549         for_each_ref(mark_uninteresting, NULL);
550
551         /* Mark potential bottoms so we won't go out of bound */
552         for (i = 0; i < nr_shallow; i++) {
553                 struct commit *c = lookup_commit(sha1[shallow[i]]);
554                 c->object.flags |= BOTTOM;
555         }
556
557         for (i = 0; i < ref->nr; i++)
558                 paint_down(&pi, ref->sha1[i], i);
559
560         if (used) {
561                 int bitmap_size = ((pi.nr_bits + 31) / 32) * sizeof(uint32_t);
562                 memset(used, 0, sizeof(*used) * info->shallow->nr);
563                 for (i = 0; i < nr_shallow; i++) {
564                         const struct commit *c = lookup_commit(sha1[shallow[i]]);
565                         uint32_t **map = ref_bitmap_at(&pi.ref_bitmap, c);
566                         if (*map)
567                                 used[shallow[i]] = xmemdupz(*map, bitmap_size);
568                 }
569                 /*
570                  * unreachable shallow commits are not removed from
571                  * "ours" and "theirs". The user is supposed to run
572                  * step 7 on every ref separately and not trust "ours"
573                  * and "theirs" any more.
574                  */
575         } else
576                 post_assign_shallow(info, &pi.ref_bitmap, ref_status);
577
578         clear_ref_bitmap(&pi.ref_bitmap);
579         for (i = 0; i < pi.slab_count; i++)
580                 free(pi.slab[i]);
581         free(pi.slab);
582         free(shallow);
583 }
584
585 struct commit_array {
586         struct commit **commits;
587         int nr, alloc;
588 };
589
590 static int add_ref(const char *refname,
591                    const unsigned char *sha1, int flags, void *cb_data)
592 {
593         struct commit_array *ca = cb_data;
594         ALLOC_GROW(ca->commits, ca->nr + 1, ca->alloc);
595         ca->commits[ca->nr] = lookup_commit_reference_gently(sha1, 1);
596         if (ca->commits[ca->nr])
597                 ca->nr++;
598         return 0;
599 }
600
601 static void update_refstatus(int *ref_status, int nr, uint32_t *bitmap)
602 {
603         int i;
604         if (!ref_status)
605                 return;
606         for (i = 0; i < nr; i++)
607                 if (bitmap[i / 32] & (1 << (i % 32)))
608                         ref_status[i]++;
609 }
610
611 /*
612  * Step 7, reachability test on "ours" at commit level
613  */
614 static void post_assign_shallow(struct shallow_info *info,
615                                 struct ref_bitmap *ref_bitmap,
616                                 int *ref_status)
617 {
618         unsigned char (*sha1)[20] = info->shallow->sha1;
619         struct commit *c;
620         uint32_t **bitmap;
621         int dst, i, j;
622         int bitmap_nr = (info->ref->nr + 31) / 32;
623         struct commit_array ca;
624
625         trace_printf_key(TRACE_KEY, "shallow: post_assign_shallow\n");
626         if (ref_status)
627                 memset(ref_status, 0, sizeof(*ref_status) * info->ref->nr);
628
629         /* Remove unreachable shallow commits from "theirs" */
630         for (i = dst = 0; i < info->nr_theirs; i++) {
631                 if (i != dst)
632                         info->theirs[dst] = info->theirs[i];
633                 c = lookup_commit(sha1[info->theirs[i]]);
634                 bitmap = ref_bitmap_at(ref_bitmap, c);
635                 if (!*bitmap)
636                         continue;
637                 for (j = 0; j < bitmap_nr; j++)
638                         if (bitmap[0][j]) {
639                                 update_refstatus(ref_status, info->ref->nr, *bitmap);
640                                 dst++;
641                                 break;
642                         }
643         }
644         info->nr_theirs = dst;
645
646         memset(&ca, 0, sizeof(ca));
647         head_ref(add_ref, &ca);
648         for_each_ref(add_ref, &ca);
649
650         /* Remove unreachable shallow commits from "ours" */
651         for (i = dst = 0; i < info->nr_ours; i++) {
652                 if (i != dst)
653                         info->ours[dst] = info->ours[i];
654                 c = lookup_commit(sha1[info->ours[i]]);
655                 bitmap = ref_bitmap_at(ref_bitmap, c);
656                 if (!*bitmap)
657                         continue;
658                 for (j = 0; j < bitmap_nr; j++)
659                         if (bitmap[0][j] &&
660                             /* Step 7, reachability test at commit level */
661                             !in_merge_bases_many(c, ca.nr, ca.commits)) {
662                                 update_refstatus(ref_status, info->ref->nr, *bitmap);
663                                 dst++;
664                                 break;
665                         }
666         }
667         info->nr_ours = dst;
668
669         free(ca.commits);
670 }
671
672 /* (Delayed) step 7, reachability test at commit level */
673 int delayed_reachability_test(struct shallow_info *si, int c)
674 {
675         if (si->need_reachability_test[c]) {
676                 struct commit *commit = lookup_commit(si->shallow->sha1[c]);
677
678                 if (!si->commits) {
679                         struct commit_array ca;
680                         memset(&ca, 0, sizeof(ca));
681                         head_ref(add_ref, &ca);
682                         for_each_ref(add_ref, &ca);
683                         si->commits = ca.commits;
684                         si->nr_commits = ca.nr;
685                 }
686
687                 si->reachable[c] = in_merge_bases_many(commit,
688                                                        si->nr_commits,
689                                                        si->commits);
690                 si->need_reachability_test[c] = 0;
691         }
692         return si->reachable[c];
693 }