Start maintenance track for 2.10.x series
[git] / shallow.c
1 #include "cache.h"
2 #include "tempfile.h"
3 #include "lockfile.h"
4 #include "commit.h"
5 #include "tag.h"
6 #include "pkt-line.h"
7 #include "remote.h"
8 #include "refs.h"
9 #include "sha1-array.h"
10 #include "diff.h"
11 #include "revision.h"
12 #include "commit-slab.h"
13
14 static int is_shallow = -1;
15 static struct stat_validity shallow_stat;
16 static char *alternate_shallow_file;
17
18 void set_alternate_shallow_file(const char *path, int override)
19 {
20         if (is_shallow != -1)
21                 die("BUG: is_repository_shallow must not be called before set_alternate_shallow_file");
22         if (alternate_shallow_file && !override)
23                 return;
24         free(alternate_shallow_file);
25         alternate_shallow_file = xstrdup_or_null(path);
26 }
27
28 int register_shallow(const unsigned char *sha1)
29 {
30         struct commit_graft *graft =
31                 xmalloc(sizeof(struct commit_graft));
32         struct commit *commit = lookup_commit(sha1);
33
34         hashcpy(graft->oid.hash, sha1);
35         graft->nr_parent = -1;
36         if (commit && commit->object.parsed)
37                 commit->parents = NULL;
38         return register_commit_graft(graft, 0);
39 }
40
41 int is_repository_shallow(void)
42 {
43         FILE *fp;
44         char buf[1024];
45         const char *path = alternate_shallow_file;
46
47         if (is_shallow >= 0)
48                 return is_shallow;
49
50         if (!path)
51                 path = git_path_shallow();
52         /*
53          * fetch-pack sets '--shallow-file ""' as an indicator that no
54          * shallow file should be used. We could just open it and it
55          * will likely fail. But let's do an explicit check instead.
56          */
57         if (!*path || (fp = fopen(path, "r")) == NULL) {
58                 stat_validity_clear(&shallow_stat);
59                 is_shallow = 0;
60                 return is_shallow;
61         }
62         stat_validity_update(&shallow_stat, fileno(fp));
63         is_shallow = 1;
64
65         while (fgets(buf, sizeof(buf), fp)) {
66                 unsigned char sha1[20];
67                 if (get_sha1_hex(buf, sha1))
68                         die("bad shallow line: %s", buf);
69                 register_shallow(sha1);
70         }
71         fclose(fp);
72         return is_shallow;
73 }
74
75 struct commit_list *get_shallow_commits(struct object_array *heads, int depth,
76                 int shallow_flag, int not_shallow_flag)
77 {
78         int i = 0, cur_depth = 0;
79         struct commit_list *result = NULL;
80         struct object_array stack = OBJECT_ARRAY_INIT;
81         struct commit *commit = NULL;
82         struct commit_graft *graft;
83
84         while (commit || i < heads->nr || stack.nr) {
85                 struct commit_list *p;
86                 if (!commit) {
87                         if (i < heads->nr) {
88                                 commit = (struct commit *)
89                                         deref_tag(heads->objects[i++].item, NULL, 0);
90                                 if (!commit || commit->object.type != OBJ_COMMIT) {
91                                         commit = NULL;
92                                         continue;
93                                 }
94                                 if (!commit->util)
95                                         commit->util = xmalloc(sizeof(int));
96                                 *(int *)commit->util = 0;
97                                 cur_depth = 0;
98                         } else {
99                                 commit = (struct commit *)
100                                         stack.objects[--stack.nr].item;
101                                 cur_depth = *(int *)commit->util;
102                         }
103                 }
104                 parse_commit_or_die(commit);
105                 cur_depth++;
106                 if ((depth != INFINITE_DEPTH && cur_depth >= depth) ||
107                     (is_repository_shallow() && !commit->parents &&
108                      (graft = lookup_commit_graft(commit->object.oid.hash)) != NULL &&
109                      graft->nr_parent < 0)) {
110                         commit_list_insert(commit, &result);
111                         commit->object.flags |= shallow_flag;
112                         commit = NULL;
113                         continue;
114                 }
115                 commit->object.flags |= not_shallow_flag;
116                 for (p = commit->parents, commit = NULL; p; p = p->next) {
117                         if (!p->item->util) {
118                                 int *pointer = xmalloc(sizeof(int));
119                                 p->item->util = pointer;
120                                 *pointer =  cur_depth;
121                         } else {
122                                 int *pointer = p->item->util;
123                                 if (cur_depth >= *pointer)
124                                         continue;
125                                 *pointer = cur_depth;
126                         }
127                         if (p->next)
128                                 add_object_array(&p->item->object,
129                                                 NULL, &stack);
130                         else {
131                                 commit = p->item;
132                                 cur_depth = *(int *)commit->util;
133                         }
134                 }
135         }
136
137         return result;
138 }
139
140 static void check_shallow_file_for_update(void)
141 {
142         if (is_shallow == -1)
143                 die("BUG: shallow must be initialized by now");
144
145         if (!stat_validity_check(&shallow_stat, git_path_shallow()))
146                 die("shallow file has changed since we read it");
147 }
148
149 #define SEEN_ONLY 1
150 #define VERBOSE   2
151
152 struct write_shallow_data {
153         struct strbuf *out;
154         int use_pack_protocol;
155         int count;
156         unsigned flags;
157 };
158
159 static int write_one_shallow(const struct commit_graft *graft, void *cb_data)
160 {
161         struct write_shallow_data *data = cb_data;
162         const char *hex = oid_to_hex(&graft->oid);
163         if (graft->nr_parent != -1)
164                 return 0;
165         if (data->flags & SEEN_ONLY) {
166                 struct commit *c = lookup_commit(graft->oid.hash);
167                 if (!c || !(c->object.flags & SEEN)) {
168                         if (data->flags & VERBOSE)
169                                 printf("Removing %s from .git/shallow\n",
170                                        oid_to_hex(&c->object.oid));
171                         return 0;
172                 }
173         }
174         data->count++;
175         if (data->use_pack_protocol)
176                 packet_buf_write(data->out, "shallow %s", hex);
177         else {
178                 strbuf_addstr(data->out, hex);
179                 strbuf_addch(data->out, '\n');
180         }
181         return 0;
182 }
183
184 static int write_shallow_commits_1(struct strbuf *out, int use_pack_protocol,
185                                    const struct sha1_array *extra,
186                                    unsigned flags)
187 {
188         struct write_shallow_data data;
189         int i;
190         data.out = out;
191         data.use_pack_protocol = use_pack_protocol;
192         data.count = 0;
193         data.flags = flags;
194         for_each_commit_graft(write_one_shallow, &data);
195         if (!extra)
196                 return data.count;
197         for (i = 0; i < extra->nr; i++) {
198                 strbuf_addstr(out, sha1_to_hex(extra->sha1[i]));
199                 strbuf_addch(out, '\n');
200                 data.count++;
201         }
202         return data.count;
203 }
204
205 int write_shallow_commits(struct strbuf *out, int use_pack_protocol,
206                           const struct sha1_array *extra)
207 {
208         return write_shallow_commits_1(out, use_pack_protocol, extra, 0);
209 }
210
211 static struct tempfile temporary_shallow;
212
213 const char *setup_temporary_shallow(const struct sha1_array *extra)
214 {
215         struct strbuf sb = STRBUF_INIT;
216         int fd;
217
218         if (write_shallow_commits(&sb, 0, extra)) {
219                 fd = xmks_tempfile(&temporary_shallow, git_path("shallow_XXXXXX"));
220
221                 if (write_in_full(fd, sb.buf, sb.len) != sb.len)
222                         die_errno("failed to write to %s",
223                                   get_tempfile_path(&temporary_shallow));
224                 close_tempfile(&temporary_shallow);
225                 strbuf_release(&sb);
226                 return get_tempfile_path(&temporary_shallow);
227         }
228         /*
229          * is_repository_shallow() sees empty string as "no shallow
230          * file".
231          */
232         return get_tempfile_path(&temporary_shallow);
233 }
234
235 void setup_alternate_shallow(struct lock_file *shallow_lock,
236                              const char **alternate_shallow_file,
237                              const struct sha1_array *extra)
238 {
239         struct strbuf sb = STRBUF_INIT;
240         int fd;
241
242         fd = hold_lock_file_for_update(shallow_lock, git_path_shallow(),
243                                        LOCK_DIE_ON_ERROR);
244         check_shallow_file_for_update();
245         if (write_shallow_commits(&sb, 0, extra)) {
246                 if (write_in_full(fd, sb.buf, sb.len) != sb.len)
247                         die_errno("failed to write to %s",
248                                   get_lock_file_path(shallow_lock));
249                 *alternate_shallow_file = get_lock_file_path(shallow_lock);
250         } else
251                 /*
252                  * is_repository_shallow() sees empty string as "no
253                  * shallow file".
254                  */
255                 *alternate_shallow_file = "";
256         strbuf_release(&sb);
257 }
258
259 static int advertise_shallow_grafts_cb(const struct commit_graft *graft, void *cb)
260 {
261         int fd = *(int *)cb;
262         if (graft->nr_parent == -1)
263                 packet_write(fd, "shallow %s\n", oid_to_hex(&graft->oid));
264         return 0;
265 }
266
267 void advertise_shallow_grafts(int fd)
268 {
269         if (!is_repository_shallow())
270                 return;
271         for_each_commit_graft(advertise_shallow_grafts_cb, &fd);
272 }
273
274 /*
275  * mark_reachable_objects() should have been run prior to this and all
276  * reachable commits marked as "SEEN".
277  */
278 void prune_shallow(int show_only)
279 {
280         static struct lock_file shallow_lock;
281         struct strbuf sb = STRBUF_INIT;
282         int fd;
283
284         if (show_only) {
285                 write_shallow_commits_1(&sb, 0, NULL, SEEN_ONLY | VERBOSE);
286                 strbuf_release(&sb);
287                 return;
288         }
289         fd = hold_lock_file_for_update(&shallow_lock, git_path_shallow(),
290                                        LOCK_DIE_ON_ERROR);
291         check_shallow_file_for_update();
292         if (write_shallow_commits_1(&sb, 0, NULL, SEEN_ONLY)) {
293                 if (write_in_full(fd, sb.buf, sb.len) != sb.len)
294                         die_errno("failed to write to %s",
295                                   get_lock_file_path(&shallow_lock));
296                 commit_lock_file(&shallow_lock);
297         } else {
298                 unlink(git_path_shallow());
299                 rollback_lock_file(&shallow_lock);
300         }
301         strbuf_release(&sb);
302 }
303
304 struct trace_key trace_shallow = TRACE_KEY_INIT(SHALLOW);
305
306 /*
307  * Step 1, split sender shallow commits into "ours" and "theirs"
308  * Step 2, clean "ours" based on .git/shallow
309  */
310 void prepare_shallow_info(struct shallow_info *info, struct sha1_array *sa)
311 {
312         int i;
313         trace_printf_key(&trace_shallow, "shallow: prepare_shallow_info\n");
314         memset(info, 0, sizeof(*info));
315         info->shallow = sa;
316         if (!sa)
317                 return;
318         ALLOC_ARRAY(info->ours, sa->nr);
319         ALLOC_ARRAY(info->theirs, sa->nr);
320         for (i = 0; i < sa->nr; i++) {
321                 if (has_sha1_file(sa->sha1[i])) {
322                         struct commit_graft *graft;
323                         graft = lookup_commit_graft(sa->sha1[i]);
324                         if (graft && graft->nr_parent < 0)
325                                 continue;
326                         info->ours[info->nr_ours++] = i;
327                 } else
328                         info->theirs[info->nr_theirs++] = i;
329         }
330 }
331
332 void clear_shallow_info(struct shallow_info *info)
333 {
334         free(info->ours);
335         free(info->theirs);
336 }
337
338 /* Step 4, remove non-existent ones in "theirs" after getting the pack */
339
340 void remove_nonexistent_theirs_shallow(struct shallow_info *info)
341 {
342         unsigned char (*sha1)[20] = info->shallow->sha1;
343         int i, dst;
344         trace_printf_key(&trace_shallow, "shallow: remove_nonexistent_theirs_shallow\n");
345         for (i = dst = 0; i < info->nr_theirs; i++) {
346                 if (i != dst)
347                         info->theirs[dst] = info->theirs[i];
348                 if (has_sha1_file(sha1[info->theirs[i]]))
349                         dst++;
350         }
351         info->nr_theirs = dst;
352 }
353
354 define_commit_slab(ref_bitmap, uint32_t *);
355
356 struct paint_info {
357         struct ref_bitmap ref_bitmap;
358         unsigned nr_bits;
359         char **slab;
360         char *free, *end;
361         unsigned slab_count;
362 };
363
364 static uint32_t *paint_alloc(struct paint_info *info)
365 {
366         unsigned nr = (info->nr_bits + 31) / 32;
367         unsigned size = nr * sizeof(uint32_t);
368         void *p;
369         if (!info->slab_count || info->free + size > info->end) {
370                 info->slab_count++;
371                 REALLOC_ARRAY(info->slab, info->slab_count);
372                 info->free = xmalloc(COMMIT_SLAB_SIZE);
373                 info->slab[info->slab_count - 1] = info->free;
374                 info->end = info->free + COMMIT_SLAB_SIZE;
375         }
376         p = info->free;
377         info->free += size;
378         return p;
379 }
380
381 /*
382  * Given a commit SHA-1, walk down to parents until either SEEN,
383  * UNINTERESTING or BOTTOM is hit. Set the id-th bit in ref_bitmap for
384  * all walked commits.
385  */
386 static void paint_down(struct paint_info *info, const unsigned char *sha1,
387                        int id)
388 {
389         unsigned int i, nr;
390         struct commit_list *head = NULL;
391         int bitmap_nr = (info->nr_bits + 31) / 32;
392         size_t bitmap_size = st_mult(sizeof(uint32_t), bitmap_nr);
393         uint32_t *tmp = xmalloc(bitmap_size); /* to be freed before return */
394         uint32_t *bitmap = paint_alloc(info);
395         struct commit *c = lookup_commit_reference_gently(sha1, 1);
396         if (!c)
397                 return;
398         memset(bitmap, 0, bitmap_size);
399         bitmap[id / 32] |= (1 << (id % 32));
400         commit_list_insert(c, &head);
401         while (head) {
402                 struct commit_list *p;
403                 struct commit *c = pop_commit(&head);
404                 uint32_t **refs = ref_bitmap_at(&info->ref_bitmap, c);
405
406                 /* XXX check "UNINTERESTING" from pack bitmaps if available */
407                 if (c->object.flags & (SEEN | UNINTERESTING))
408                         continue;
409                 else
410                         c->object.flags |= SEEN;
411
412                 if (*refs == NULL)
413                         *refs = bitmap;
414                 else {
415                         memcpy(tmp, *refs, bitmap_size);
416                         for (i = 0; i < bitmap_nr; i++)
417                                 tmp[i] |= bitmap[i];
418                         if (memcmp(tmp, *refs, bitmap_size)) {
419                                 *refs = paint_alloc(info);
420                                 memcpy(*refs, tmp, bitmap_size);
421                         }
422                 }
423
424                 if (c->object.flags & BOTTOM)
425                         continue;
426
427                 if (parse_commit(c))
428                         die("unable to parse commit %s",
429                             oid_to_hex(&c->object.oid));
430
431                 for (p = c->parents; p; p = p->next) {
432                         uint32_t **p_refs = ref_bitmap_at(&info->ref_bitmap,
433                                                           p->item);
434                         if (p->item->object.flags & SEEN)
435                                 continue;
436                         if (*p_refs == NULL || *p_refs == *refs)
437                                 *p_refs = *refs;
438                         commit_list_insert(p->item, &head);
439                 }
440         }
441
442         nr = get_max_object_index();
443         for (i = 0; i < nr; i++) {
444                 struct object *o = get_indexed_object(i);
445                 if (o && o->type == OBJ_COMMIT)
446                         o->flags &= ~SEEN;
447         }
448
449         free(tmp);
450 }
451
452 static int mark_uninteresting(const char *refname, const struct object_id *oid,
453                               int flags, void *cb_data)
454 {
455         struct commit *commit = lookup_commit_reference_gently(oid->hash, 1);
456         if (!commit)
457                 return 0;
458         commit->object.flags |= UNINTERESTING;
459         mark_parents_uninteresting(commit);
460         return 0;
461 }
462
463 static void post_assign_shallow(struct shallow_info *info,
464                                 struct ref_bitmap *ref_bitmap,
465                                 int *ref_status);
466 /*
467  * Step 6(+7), associate shallow commits with new refs
468  *
469  * info->ref must be initialized before calling this function.
470  *
471  * If used is not NULL, it's an array of info->shallow->nr
472  * bitmaps. The n-th bit set in the m-th bitmap if ref[n] needs the
473  * m-th shallow commit from info->shallow.
474  *
475  * If used is NULL, "ours" and "theirs" are updated. And if ref_status
476  * is not NULL it's an array of ref->nr ints. ref_status[i] is true if
477  * the ref needs some shallow commits from either info->ours or
478  * info->theirs.
479  */
480 void assign_shallow_commits_to_refs(struct shallow_info *info,
481                                     uint32_t **used, int *ref_status)
482 {
483         unsigned char (*sha1)[20] = info->shallow->sha1;
484         struct sha1_array *ref = info->ref;
485         unsigned int i, nr;
486         int *shallow, nr_shallow = 0;
487         struct paint_info pi;
488
489         trace_printf_key(&trace_shallow, "shallow: assign_shallow_commits_to_refs\n");
490         ALLOC_ARRAY(shallow, info->nr_ours + info->nr_theirs);
491         for (i = 0; i < info->nr_ours; i++)
492                 shallow[nr_shallow++] = info->ours[i];
493         for (i = 0; i < info->nr_theirs; i++)
494                 shallow[nr_shallow++] = info->theirs[i];
495
496         /*
497          * Prepare the commit graph to track what refs can reach what
498          * (new) shallow commits.
499          */
500         nr = get_max_object_index();
501         for (i = 0; i < nr; i++) {
502                 struct object *o = get_indexed_object(i);
503                 if (!o || o->type != OBJ_COMMIT)
504                         continue;
505
506                 o->flags &= ~(UNINTERESTING | BOTTOM | SEEN);
507         }
508
509         memset(&pi, 0, sizeof(pi));
510         init_ref_bitmap(&pi.ref_bitmap);
511         pi.nr_bits = ref->nr;
512
513         /*
514          * "--not --all" to cut short the traversal if new refs
515          * connect to old refs. If not (e.g. force ref updates) it'll
516          * have to go down to the current shallow commits.
517          */
518         head_ref(mark_uninteresting, NULL);
519         for_each_ref(mark_uninteresting, NULL);
520
521         /* Mark potential bottoms so we won't go out of bound */
522         for (i = 0; i < nr_shallow; i++) {
523                 struct commit *c = lookup_commit(sha1[shallow[i]]);
524                 c->object.flags |= BOTTOM;
525         }
526
527         for (i = 0; i < ref->nr; i++)
528                 paint_down(&pi, ref->sha1[i], i);
529
530         if (used) {
531                 int bitmap_size = ((pi.nr_bits + 31) / 32) * sizeof(uint32_t);
532                 memset(used, 0, sizeof(*used) * info->shallow->nr);
533                 for (i = 0; i < nr_shallow; i++) {
534                         const struct commit *c = lookup_commit(sha1[shallow[i]]);
535                         uint32_t **map = ref_bitmap_at(&pi.ref_bitmap, c);
536                         if (*map)
537                                 used[shallow[i]] = xmemdupz(*map, bitmap_size);
538                 }
539                 /*
540                  * unreachable shallow commits are not removed from
541                  * "ours" and "theirs". The user is supposed to run
542                  * step 7 on every ref separately and not trust "ours"
543                  * and "theirs" any more.
544                  */
545         } else
546                 post_assign_shallow(info, &pi.ref_bitmap, ref_status);
547
548         clear_ref_bitmap(&pi.ref_bitmap);
549         for (i = 0; i < pi.slab_count; i++)
550                 free(pi.slab[i]);
551         free(pi.slab);
552         free(shallow);
553 }
554
555 struct commit_array {
556         struct commit **commits;
557         int nr, alloc;
558 };
559
560 static int add_ref(const char *refname, const struct object_id *oid,
561                    int flags, void *cb_data)
562 {
563         struct commit_array *ca = cb_data;
564         ALLOC_GROW(ca->commits, ca->nr + 1, ca->alloc);
565         ca->commits[ca->nr] = lookup_commit_reference_gently(oid->hash, 1);
566         if (ca->commits[ca->nr])
567                 ca->nr++;
568         return 0;
569 }
570
571 static void update_refstatus(int *ref_status, int nr, uint32_t *bitmap)
572 {
573         int i;
574         if (!ref_status)
575                 return;
576         for (i = 0; i < nr; i++)
577                 if (bitmap[i / 32] & (1 << (i % 32)))
578                         ref_status[i]++;
579 }
580
581 /*
582  * Step 7, reachability test on "ours" at commit level
583  */
584 static void post_assign_shallow(struct shallow_info *info,
585                                 struct ref_bitmap *ref_bitmap,
586                                 int *ref_status)
587 {
588         unsigned char (*sha1)[20] = info->shallow->sha1;
589         struct commit *c;
590         uint32_t **bitmap;
591         int dst, i, j;
592         int bitmap_nr = (info->ref->nr + 31) / 32;
593         struct commit_array ca;
594
595         trace_printf_key(&trace_shallow, "shallow: post_assign_shallow\n");
596         if (ref_status)
597                 memset(ref_status, 0, sizeof(*ref_status) * info->ref->nr);
598
599         /* Remove unreachable shallow commits from "theirs" */
600         for (i = dst = 0; i < info->nr_theirs; i++) {
601                 if (i != dst)
602                         info->theirs[dst] = info->theirs[i];
603                 c = lookup_commit(sha1[info->theirs[i]]);
604                 bitmap = ref_bitmap_at(ref_bitmap, c);
605                 if (!*bitmap)
606                         continue;
607                 for (j = 0; j < bitmap_nr; j++)
608                         if (bitmap[0][j]) {
609                                 update_refstatus(ref_status, info->ref->nr, *bitmap);
610                                 dst++;
611                                 break;
612                         }
613         }
614         info->nr_theirs = dst;
615
616         memset(&ca, 0, sizeof(ca));
617         head_ref(add_ref, &ca);
618         for_each_ref(add_ref, &ca);
619
620         /* Remove unreachable shallow commits from "ours" */
621         for (i = dst = 0; i < info->nr_ours; i++) {
622                 if (i != dst)
623                         info->ours[dst] = info->ours[i];
624                 c = lookup_commit(sha1[info->ours[i]]);
625                 bitmap = ref_bitmap_at(ref_bitmap, c);
626                 if (!*bitmap)
627                         continue;
628                 for (j = 0; j < bitmap_nr; j++)
629                         if (bitmap[0][j] &&
630                             /* Step 7, reachability test at commit level */
631                             !in_merge_bases_many(c, ca.nr, ca.commits)) {
632                                 update_refstatus(ref_status, info->ref->nr, *bitmap);
633                                 dst++;
634                                 break;
635                         }
636         }
637         info->nr_ours = dst;
638
639         free(ca.commits);
640 }
641
642 /* (Delayed) step 7, reachability test at commit level */
643 int delayed_reachability_test(struct shallow_info *si, int c)
644 {
645         if (si->need_reachability_test[c]) {
646                 struct commit *commit = lookup_commit(si->shallow->sha1[c]);
647
648                 if (!si->commits) {
649                         struct commit_array ca;
650
651                         memset(&ca, 0, sizeof(ca));
652                         head_ref(add_ref, &ca);
653                         for_each_ref(add_ref, &ca);
654                         si->commits = ca.commits;
655                         si->nr_commits = ca.nr;
656                 }
657
658                 si->reachable[c] = in_merge_bases_many(commit,
659                                                        si->nr_commits,
660                                                        si->commits);
661                 si->need_reachability_test[c] = 0;
662         }
663         return si->reachable[c];
664 }