builtin-commit: use reduce_heads() only when appropriate
[git] / builtin-rev-list.c
1 #include "cache.h"
2 #include "refs.h"
3 #include "tag.h"
4 #include "commit.h"
5 #include "tree.h"
6 #include "blob.h"
7 #include "tree-walk.h"
8 #include "diff.h"
9 #include "revision.h"
10 #include "list-objects.h"
11 #include "builtin.h"
12 #include "log-tree.h"
13 #include "graph.h"
14
15 /* bits #0-15 in revision.h */
16
17 #define COUNTED         (1u<<16)
18
19 static const char rev_list_usage[] =
20 "git rev-list [OPTION] <commit-id>... [ -- paths... ]\n"
21 "  limiting output:\n"
22 "    --max-count=nr\n"
23 "    --max-age=epoch\n"
24 "    --min-age=epoch\n"
25 "    --sparse\n"
26 "    --no-merges\n"
27 "    --remove-empty\n"
28 "    --all\n"
29 "    --branches\n"
30 "    --tags\n"
31 "    --remotes\n"
32 "    --stdin\n"
33 "    --quiet\n"
34 "  ordering output:\n"
35 "    --topo-order\n"
36 "    --date-order\n"
37 "    --reverse\n"
38 "  formatting output:\n"
39 "    --parents\n"
40 "    --children\n"
41 "    --objects | --objects-edge\n"
42 "    --unpacked\n"
43 "    --header | --pretty\n"
44 "    --abbrev=nr | --no-abbrev\n"
45 "    --abbrev-commit\n"
46 "    --left-right\n"
47 "  special purpose:\n"
48 "    --bisect\n"
49 "    --bisect-vars\n"
50 "    --bisect-all"
51 ;
52
53 static struct rev_info revs;
54
55 static int bisect_list;
56 static int show_timestamp;
57 static int hdr_termination;
58 static const char *header_prefix;
59
60 static void finish_commit(struct commit *commit);
61 static void show_commit(struct commit *commit)
62 {
63         graph_show_commit(revs.graph);
64
65         if (show_timestamp)
66                 printf("%lu ", commit->date);
67         if (header_prefix)
68                 fputs(header_prefix, stdout);
69
70         if (!revs.graph) {
71                 if (commit->object.flags & BOUNDARY)
72                         putchar('-');
73                 else if (commit->object.flags & UNINTERESTING)
74                         putchar('^');
75                 else if (revs.left_right) {
76                         if (commit->object.flags & SYMMETRIC_LEFT)
77                                 putchar('<');
78                         else
79                                 putchar('>');
80                 }
81         }
82         if (revs.abbrev_commit && revs.abbrev)
83                 fputs(find_unique_abbrev(commit->object.sha1, revs.abbrev),
84                       stdout);
85         else
86                 fputs(sha1_to_hex(commit->object.sha1), stdout);
87         if (revs.print_parents) {
88                 struct commit_list *parents = commit->parents;
89                 while (parents) {
90                         printf(" %s", sha1_to_hex(parents->item->object.sha1));
91                         parents = parents->next;
92                 }
93         }
94         if (revs.children.name) {
95                 struct commit_list *children;
96
97                 children = lookup_decoration(&revs.children, &commit->object);
98                 while (children) {
99                         printf(" %s", sha1_to_hex(children->item->object.sha1));
100                         children = children->next;
101                 }
102         }
103         show_decorations(commit);
104         if (revs.commit_format == CMIT_FMT_ONELINE)
105                 putchar(' ');
106         else
107                 putchar('\n');
108
109         if (revs.verbose_header && commit->buffer) {
110                 struct strbuf buf;
111                 strbuf_init(&buf, 0);
112                 pretty_print_commit(revs.commit_format, commit,
113                                     &buf, revs.abbrev, NULL, NULL,
114                                     revs.date_mode, 0);
115                 if (revs.graph) {
116                         if (buf.len) {
117                                 if (revs.commit_format != CMIT_FMT_ONELINE)
118                                         graph_show_oneline(revs.graph);
119
120                                 graph_show_commit_msg(revs.graph, &buf);
121
122                                 /*
123                                  * Add a newline after the commit message.
124                                  *
125                                  * Usually, this newline produces a blank
126                                  * padding line between entries, in which case
127                                  * we need to add graph padding on this line.
128                                  *
129                                  * However, the commit message may not end in a
130                                  * newline.  In this case the newline simply
131                                  * ends the last line of the commit message,
132                                  * and we don't need any graph output.  (This
133                                  * always happens with CMIT_FMT_ONELINE, and it
134                                  * happens with CMIT_FMT_USERFORMAT when the
135                                  * format doesn't explicitly end in a newline.)
136                                  */
137                                 if (buf.len && buf.buf[buf.len - 1] == '\n')
138                                         graph_show_padding(revs.graph);
139                                 putchar('\n');
140                         } else {
141                                 /*
142                                  * If the message buffer is empty, just show
143                                  * the rest of the graph output for this
144                                  * commit.
145                                  */
146                                 if (graph_show_remainder(revs.graph))
147                                         putchar('\n');
148                         }
149                 } else {
150                         if (buf.len)
151                                 printf("%s%c", buf.buf, hdr_termination);
152                 }
153                 strbuf_release(&buf);
154         } else {
155                 if (graph_show_remainder(revs.graph))
156                         putchar('\n');
157         }
158         maybe_flush_or_die(stdout, "stdout");
159         finish_commit(commit);
160 }
161
162 static void finish_commit(struct commit *commit)
163 {
164         if (commit->parents) {
165                 free_commit_list(commit->parents);
166                 commit->parents = NULL;
167         }
168         free(commit->buffer);
169         commit->buffer = NULL;
170 }
171
172 static void finish_object(struct object_array_entry *p)
173 {
174         if (p->item->type == OBJ_BLOB && !has_sha1_file(p->item->sha1))
175                 die("missing blob object '%s'", sha1_to_hex(p->item->sha1));
176 }
177
178 static void show_object(struct object_array_entry *p)
179 {
180         /* An object with name "foo\n0000000..." can be used to
181          * confuse downstream "git pack-objects" very badly.
182          */
183         const char *ep = strchr(p->name, '\n');
184
185         finish_object(p);
186         if (ep) {
187                 printf("%s %.*s\n", sha1_to_hex(p->item->sha1),
188                        (int) (ep - p->name),
189                        p->name);
190         }
191         else
192                 printf("%s %s\n", sha1_to_hex(p->item->sha1), p->name);
193 }
194
195 static void show_edge(struct commit *commit)
196 {
197         printf("-%s\n", sha1_to_hex(commit->object.sha1));
198 }
199
200 /*
201  * This is a truly stupid algorithm, but it's only
202  * used for bisection, and we just don't care enough.
203  *
204  * We care just barely enough to avoid recursing for
205  * non-merge entries.
206  */
207 static int count_distance(struct commit_list *entry)
208 {
209         int nr = 0;
210
211         while (entry) {
212                 struct commit *commit = entry->item;
213                 struct commit_list *p;
214
215                 if (commit->object.flags & (UNINTERESTING | COUNTED))
216                         break;
217                 if (!(commit->object.flags & TREESAME))
218                         nr++;
219                 commit->object.flags |= COUNTED;
220                 p = commit->parents;
221                 entry = p;
222                 if (p) {
223                         p = p->next;
224                         while (p) {
225                                 nr += count_distance(p);
226                                 p = p->next;
227                         }
228                 }
229         }
230
231         return nr;
232 }
233
234 static void clear_distance(struct commit_list *list)
235 {
236         while (list) {
237                 struct commit *commit = list->item;
238                 commit->object.flags &= ~COUNTED;
239                 list = list->next;
240         }
241 }
242
243 #define DEBUG_BISECT 0
244
245 static inline int weight(struct commit_list *elem)
246 {
247         return *((int*)(elem->item->util));
248 }
249
250 static inline void weight_set(struct commit_list *elem, int weight)
251 {
252         *((int*)(elem->item->util)) = weight;
253 }
254
255 static int count_interesting_parents(struct commit *commit)
256 {
257         struct commit_list *p;
258         int count;
259
260         for (count = 0, p = commit->parents; p; p = p->next) {
261                 if (p->item->object.flags & UNINTERESTING)
262                         continue;
263                 count++;
264         }
265         return count;
266 }
267
268 static inline int halfway(struct commit_list *p, int nr)
269 {
270         /*
271          * Don't short-cut something we are not going to return!
272          */
273         if (p->item->object.flags & TREESAME)
274                 return 0;
275         if (DEBUG_BISECT)
276                 return 0;
277         /*
278          * 2 and 3 are halfway of 5.
279          * 3 is halfway of 6 but 2 and 4 are not.
280          */
281         switch (2 * weight(p) - nr) {
282         case -1: case 0: case 1:
283                 return 1;
284         default:
285                 return 0;
286         }
287 }
288
289 #if !DEBUG_BISECT
290 #define show_list(a,b,c,d) do { ; } while (0)
291 #else
292 static void show_list(const char *debug, int counted, int nr,
293                       struct commit_list *list)
294 {
295         struct commit_list *p;
296
297         fprintf(stderr, "%s (%d/%d)\n", debug, counted, nr);
298
299         for (p = list; p; p = p->next) {
300                 struct commit_list *pp;
301                 struct commit *commit = p->item;
302                 unsigned flags = commit->object.flags;
303                 enum object_type type;
304                 unsigned long size;
305                 char *buf = read_sha1_file(commit->object.sha1, &type, &size);
306                 char *ep, *sp;
307
308                 fprintf(stderr, "%c%c%c ",
309                         (flags & TREESAME) ? ' ' : 'T',
310                         (flags & UNINTERESTING) ? 'U' : ' ',
311                         (flags & COUNTED) ? 'C' : ' ');
312                 if (commit->util)
313                         fprintf(stderr, "%3d", weight(p));
314                 else
315                         fprintf(stderr, "---");
316                 fprintf(stderr, " %.*s", 8, sha1_to_hex(commit->object.sha1));
317                 for (pp = commit->parents; pp; pp = pp->next)
318                         fprintf(stderr, " %.*s", 8,
319                                 sha1_to_hex(pp->item->object.sha1));
320
321                 sp = strstr(buf, "\n\n");
322                 if (sp) {
323                         sp += 2;
324                         for (ep = sp; *ep && *ep != '\n'; ep++)
325                                 ;
326                         fprintf(stderr, " %.*s", (int)(ep - sp), sp);
327                 }
328                 fprintf(stderr, "\n");
329         }
330 }
331 #endif /* DEBUG_BISECT */
332
333 static struct commit_list *best_bisection(struct commit_list *list, int nr)
334 {
335         struct commit_list *p, *best;
336         int best_distance = -1;
337
338         best = list;
339         for (p = list; p; p = p->next) {
340                 int distance;
341                 unsigned flags = p->item->object.flags;
342
343                 if (flags & TREESAME)
344                         continue;
345                 distance = weight(p);
346                 if (nr - distance < distance)
347                         distance = nr - distance;
348                 if (distance > best_distance) {
349                         best = p;
350                         best_distance = distance;
351                 }
352         }
353
354         return best;
355 }
356
357 struct commit_dist {
358         struct commit *commit;
359         int distance;
360 };
361
362 static int compare_commit_dist(const void *a_, const void *b_)
363 {
364         struct commit_dist *a, *b;
365
366         a = (struct commit_dist *)a_;
367         b = (struct commit_dist *)b_;
368         if (a->distance != b->distance)
369                 return b->distance - a->distance; /* desc sort */
370         return hashcmp(a->commit->object.sha1, b->commit->object.sha1);
371 }
372
373 static struct commit_list *best_bisection_sorted(struct commit_list *list, int nr)
374 {
375         struct commit_list *p;
376         struct commit_dist *array = xcalloc(nr, sizeof(*array));
377         int cnt, i;
378
379         for (p = list, cnt = 0; p; p = p->next) {
380                 int distance;
381                 unsigned flags = p->item->object.flags;
382
383                 if (flags & TREESAME)
384                         continue;
385                 distance = weight(p);
386                 if (nr - distance < distance)
387                         distance = nr - distance;
388                 array[cnt].commit = p->item;
389                 array[cnt].distance = distance;
390                 cnt++;
391         }
392         qsort(array, cnt, sizeof(*array), compare_commit_dist);
393         for (p = list, i = 0; i < cnt; i++) {
394                 struct name_decoration *r = xmalloc(sizeof(*r) + 100);
395                 struct object *obj = &(array[i].commit->object);
396
397                 sprintf(r->name, "dist=%d", array[i].distance);
398                 r->next = add_decoration(&name_decoration, obj, r);
399                 p->item = array[i].commit;
400                 p = p->next;
401         }
402         if (p)
403                 p->next = NULL;
404         free(array);
405         return list;
406 }
407
408 /*
409  * zero or positive weight is the number of interesting commits it can
410  * reach, including itself.  Especially, weight = 0 means it does not
411  * reach any tree-changing commits (e.g. just above uninteresting one
412  * but traversal is with pathspec).
413  *
414  * weight = -1 means it has one parent and its distance is yet to
415  * be computed.
416  *
417  * weight = -2 means it has more than one parent and its distance is
418  * unknown.  After running count_distance() first, they will get zero
419  * or positive distance.
420  */
421 static struct commit_list *do_find_bisection(struct commit_list *list,
422                                              int nr, int *weights,
423                                              int find_all)
424 {
425         int n, counted;
426         struct commit_list *p;
427
428         counted = 0;
429
430         for (n = 0, p = list; p; p = p->next) {
431                 struct commit *commit = p->item;
432                 unsigned flags = commit->object.flags;
433
434                 p->item->util = &weights[n++];
435                 switch (count_interesting_parents(commit)) {
436                 case 0:
437                         if (!(flags & TREESAME)) {
438                                 weight_set(p, 1);
439                                 counted++;
440                                 show_list("bisection 2 count one",
441                                           counted, nr, list);
442                         }
443                         /*
444                          * otherwise, it is known not to reach any
445                          * tree-changing commit and gets weight 0.
446                          */
447                         break;
448                 case 1:
449                         weight_set(p, -1);
450                         break;
451                 default:
452                         weight_set(p, -2);
453                         break;
454                 }
455         }
456
457         show_list("bisection 2 initialize", counted, nr, list);
458
459         /*
460          * If you have only one parent in the resulting set
461          * then you can reach one commit more than that parent
462          * can reach.  So we do not have to run the expensive
463          * count_distance() for single strand of pearls.
464          *
465          * However, if you have more than one parents, you cannot
466          * just add their distance and one for yourself, since
467          * they usually reach the same ancestor and you would
468          * end up counting them twice that way.
469          *
470          * So we will first count distance of merges the usual
471          * way, and then fill the blanks using cheaper algorithm.
472          */
473         for (p = list; p; p = p->next) {
474                 if (p->item->object.flags & UNINTERESTING)
475                         continue;
476                 if (weight(p) != -2)
477                         continue;
478                 weight_set(p, count_distance(p));
479                 clear_distance(list);
480
481                 /* Does it happen to be at exactly half-way? */
482                 if (!find_all && halfway(p, nr))
483                         return p;
484                 counted++;
485         }
486
487         show_list("bisection 2 count_distance", counted, nr, list);
488
489         while (counted < nr) {
490                 for (p = list; p; p = p->next) {
491                         struct commit_list *q;
492                         unsigned flags = p->item->object.flags;
493
494                         if (0 <= weight(p))
495                                 continue;
496                         for (q = p->item->parents; q; q = q->next) {
497                                 if (q->item->object.flags & UNINTERESTING)
498                                         continue;
499                                 if (0 <= weight(q))
500                                         break;
501                         }
502                         if (!q)
503                                 continue;
504
505                         /*
506                          * weight for p is unknown but q is known.
507                          * add one for p itself if p is to be counted,
508                          * otherwise inherit it from q directly.
509                          */
510                         if (!(flags & TREESAME)) {
511                                 weight_set(p, weight(q)+1);
512                                 counted++;
513                                 show_list("bisection 2 count one",
514                                           counted, nr, list);
515                         }
516                         else
517                                 weight_set(p, weight(q));
518
519                         /* Does it happen to be at exactly half-way? */
520                         if (!find_all && halfway(p, nr))
521                                 return p;
522                 }
523         }
524
525         show_list("bisection 2 counted all", counted, nr, list);
526
527         if (!find_all)
528                 return best_bisection(list, nr);
529         else
530                 return best_bisection_sorted(list, nr);
531 }
532
533 static struct commit_list *find_bisection(struct commit_list *list,
534                                           int *reaches, int *all,
535                                           int find_all)
536 {
537         int nr, on_list;
538         struct commit_list *p, *best, *next, *last;
539         int *weights;
540
541         show_list("bisection 2 entry", 0, 0, list);
542
543         /*
544          * Count the number of total and tree-changing items on the
545          * list, while reversing the list.
546          */
547         for (nr = on_list = 0, last = NULL, p = list;
548              p;
549              p = next) {
550                 unsigned flags = p->item->object.flags;
551
552                 next = p->next;
553                 if (flags & UNINTERESTING)
554                         continue;
555                 p->next = last;
556                 last = p;
557                 if (!(flags & TREESAME))
558                         nr++;
559                 on_list++;
560         }
561         list = last;
562         show_list("bisection 2 sorted", 0, nr, list);
563
564         *all = nr;
565         weights = xcalloc(on_list, sizeof(*weights));
566
567         /* Do the real work of finding bisection commit. */
568         best = do_find_bisection(list, nr, weights, find_all);
569         if (best) {
570                 if (!find_all)
571                         best->next = NULL;
572                 *reaches = weight(best);
573         }
574         free(weights);
575         return best;
576 }
577
578 int cmd_rev_list(int argc, const char **argv, const char *prefix)
579 {
580         struct commit_list *list;
581         int i;
582         int read_from_stdin = 0;
583         int bisect_show_vars = 0;
584         int bisect_find_all = 0;
585         int quiet = 0;
586
587         git_config(git_default_config, NULL);
588         init_revisions(&revs, prefix);
589         revs.abbrev = 0;
590         revs.commit_format = CMIT_FMT_UNSPECIFIED;
591         argc = setup_revisions(argc, argv, &revs, NULL);
592
593         quiet = DIFF_OPT_TST(&revs.diffopt, QUIET);
594         for (i = 1 ; i < argc; i++) {
595                 const char *arg = argv[i];
596
597                 if (!strcmp(arg, "--header")) {
598                         revs.verbose_header = 1;
599                         continue;
600                 }
601                 if (!strcmp(arg, "--timestamp")) {
602                         show_timestamp = 1;
603                         continue;
604                 }
605                 if (!strcmp(arg, "--bisect")) {
606                         bisect_list = 1;
607                         continue;
608                 }
609                 if (!strcmp(arg, "--bisect-all")) {
610                         bisect_list = 1;
611                         bisect_find_all = 1;
612                         continue;
613                 }
614                 if (!strcmp(arg, "--bisect-vars")) {
615                         bisect_list = 1;
616                         bisect_show_vars = 1;
617                         continue;
618                 }
619                 if (!strcmp(arg, "--stdin")) {
620                         if (read_from_stdin++)
621                                 die("--stdin given twice?");
622                         read_revisions_from_stdin(&revs);
623                         continue;
624                 }
625                 usage(rev_list_usage);
626
627         }
628         if (revs.commit_format != CMIT_FMT_UNSPECIFIED) {
629                 /* The command line has a --pretty  */
630                 hdr_termination = '\n';
631                 if (revs.commit_format == CMIT_FMT_ONELINE)
632                         header_prefix = "";
633                 else
634                         header_prefix = "commit ";
635         }
636         else if (revs.verbose_header)
637                 /* Only --header was specified */
638                 revs.commit_format = CMIT_FMT_RAW;
639
640         list = revs.commits;
641
642         if ((!list &&
643              (!(revs.tag_objects||revs.tree_objects||revs.blob_objects) &&
644               !revs.pending.nr)) ||
645             revs.diff)
646                 usage(rev_list_usage);
647
648         save_commit_buffer = revs.verbose_header ||
649                 revs.grep_filter.pattern_list;
650         if (bisect_list)
651                 revs.limited = 1;
652
653         if (prepare_revision_walk(&revs))
654                 die("revision walk setup failed");
655         if (revs.tree_objects)
656                 mark_edges_uninteresting(revs.commits, &revs, show_edge);
657
658         if (bisect_list) {
659                 int reaches = reaches, all = all;
660
661                 revs.commits = find_bisection(revs.commits, &reaches, &all,
662                                               bisect_find_all);
663                 if (bisect_show_vars) {
664                         int cnt;
665                         char hex[41];
666                         if (!revs.commits)
667                                 return 1;
668                         /*
669                          * revs.commits can reach "reaches" commits among
670                          * "all" commits.  If it is good, then there are
671                          * (all-reaches) commits left to be bisected.
672                          * On the other hand, if it is bad, then the set
673                          * to bisect is "reaches".
674                          * A bisect set of size N has (N-1) commits further
675                          * to test, as we already know one bad one.
676                          */
677                         cnt = all - reaches;
678                         if (cnt < reaches)
679                                 cnt = reaches;
680                         strcpy(hex, sha1_to_hex(revs.commits->item->object.sha1));
681
682                         if (bisect_find_all) {
683                                 traverse_commit_list(&revs, show_commit, show_object);
684                                 printf("------\n");
685                         }
686
687                         printf("bisect_rev=%s\n"
688                                "bisect_nr=%d\n"
689                                "bisect_good=%d\n"
690                                "bisect_bad=%d\n"
691                                "bisect_all=%d\n",
692                                hex,
693                                cnt - 1,
694                                all - reaches - 1,
695                                reaches - 1,
696                                all);
697                         return 0;
698                 }
699         }
700
701         traverse_commit_list(&revs,
702                 quiet ? finish_commit : show_commit,
703                 quiet ? finish_object : show_object);
704
705         return 0;
706 }