Merge branch 'tm/doc-submodule-absorb-fix'
[git] / diffcore-rename.c
1 /*
2  * Copyright (C) 2005 Junio C Hamano
3  */
4 #include "cache.h"
5 #include "diff.h"
6 #include "diffcore.h"
7 #include "object-store.h"
8 #include "hashmap.h"
9 #include "progress.h"
10
11 /* Table of rename/copy destinations */
12
13 static struct diff_rename_dst {
14         struct diff_filespec *two;
15         struct diff_filepair *pair;
16 } *rename_dst;
17 static int rename_dst_nr, rename_dst_alloc;
18
19 static int find_rename_dst(struct diff_filespec *two)
20 {
21         int first, last;
22
23         first = 0;
24         last = rename_dst_nr;
25         while (last > first) {
26                 int next = first + ((last - first) >> 1);
27                 struct diff_rename_dst *dst = &(rename_dst[next]);
28                 int cmp = strcmp(two->path, dst->two->path);
29                 if (!cmp)
30                         return next;
31                 if (cmp < 0) {
32                         last = next;
33                         continue;
34                 }
35                 first = next+1;
36         }
37         return -first - 1;
38 }
39
40 static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two)
41 {
42         int ofs = find_rename_dst(two);
43         return ofs < 0 ? NULL : &rename_dst[ofs];
44 }
45
46 /*
47  * Returns 0 on success, -1 if we found a duplicate.
48  */
49 static int add_rename_dst(struct diff_filespec *two)
50 {
51         int first = find_rename_dst(two);
52
53         if (first >= 0)
54                 return -1;
55         first = -first - 1;
56
57         /* insert to make it at "first" */
58         ALLOC_GROW(rename_dst, rename_dst_nr + 1, rename_dst_alloc);
59         rename_dst_nr++;
60         if (first < rename_dst_nr)
61                 MOVE_ARRAY(rename_dst + first + 1, rename_dst + first,
62                            rename_dst_nr - first - 1);
63         rename_dst[first].two = alloc_filespec(two->path);
64         fill_filespec(rename_dst[first].two, &two->oid, two->oid_valid,
65                       two->mode);
66         rename_dst[first].pair = NULL;
67         return 0;
68 }
69
70 /* Table of rename/copy src files */
71 static struct diff_rename_src {
72         struct diff_filepair *p;
73         unsigned short score; /* to remember the break score */
74 } *rename_src;
75 static int rename_src_nr, rename_src_alloc;
76
77 static struct diff_rename_src *register_rename_src(struct diff_filepair *p)
78 {
79         int first, last;
80         struct diff_filespec *one = p->one;
81         unsigned short score = p->score;
82
83         first = 0;
84         last = rename_src_nr;
85         while (last > first) {
86                 int next = first + ((last - first) >> 1);
87                 struct diff_rename_src *src = &(rename_src[next]);
88                 int cmp = strcmp(one->path, src->p->one->path);
89                 if (!cmp)
90                         return src;
91                 if (cmp < 0) {
92                         last = next;
93                         continue;
94                 }
95                 first = next+1;
96         }
97
98         /* insert to make it at "first" */
99         ALLOC_GROW(rename_src, rename_src_nr + 1, rename_src_alloc);
100         rename_src_nr++;
101         if (first < rename_src_nr)
102                 MOVE_ARRAY(rename_src + first + 1, rename_src + first,
103                            rename_src_nr - first - 1);
104         rename_src[first].p = p;
105         rename_src[first].score = score;
106         return &(rename_src[first]);
107 }
108
109 static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
110 {
111         int src_len = strlen(src->path), dst_len = strlen(dst->path);
112         while (src_len && dst_len) {
113                 char c1 = src->path[--src_len];
114                 char c2 = dst->path[--dst_len];
115                 if (c1 != c2)
116                         return 0;
117                 if (c1 == '/')
118                         return 1;
119         }
120         return (!src_len || src->path[src_len - 1] == '/') &&
121                 (!dst_len || dst->path[dst_len - 1] == '/');
122 }
123
124 struct diff_score {
125         int src; /* index in rename_src */
126         int dst; /* index in rename_dst */
127         unsigned short score;
128         short name_score;
129 };
130
131 static int estimate_similarity(struct repository *r,
132                                struct diff_filespec *src,
133                                struct diff_filespec *dst,
134                                int minimum_score)
135 {
136         /* src points at a file that existed in the original tree (or
137          * optionally a file in the destination tree) and dst points
138          * at a newly created file.  They may be quite similar, in which
139          * case we want to say src is renamed to dst or src is copied into
140          * dst, and then some edit has been applied to dst.
141          *
142          * Compare them and return how similar they are, representing
143          * the score as an integer between 0 and MAX_SCORE.
144          *
145          * When there is an exact match, it is considered a better
146          * match than anything else; the destination does not even
147          * call into this function in that case.
148          */
149         unsigned long max_size, delta_size, base_size, src_copied, literal_added;
150         int score;
151
152         /* We deal only with regular files.  Symlink renames are handled
153          * only when they are exact matches --- in other words, no edits
154          * after renaming.
155          */
156         if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
157                 return 0;
158
159         /*
160          * Need to check that source and destination sizes are
161          * filled in before comparing them.
162          *
163          * If we already have "cnt_data" filled in, we know it's
164          * all good (avoid checking the size for zero, as that
165          * is a possible size - we really should have a flag to
166          * say whether the size is valid or not!)
167          */
168         if (!src->cnt_data &&
169             diff_populate_filespec(r, src, CHECK_SIZE_ONLY))
170                 return 0;
171         if (!dst->cnt_data &&
172             diff_populate_filespec(r, dst, CHECK_SIZE_ONLY))
173                 return 0;
174
175         max_size = ((src->size > dst->size) ? src->size : dst->size);
176         base_size = ((src->size < dst->size) ? src->size : dst->size);
177         delta_size = max_size - base_size;
178
179         /* We would not consider edits that change the file size so
180          * drastically.  delta_size must be smaller than
181          * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
182          *
183          * Note that base_size == 0 case is handled here already
184          * and the final score computation below would not have a
185          * divide-by-zero issue.
186          */
187         if (max_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
188                 return 0;
189
190         if (!src->cnt_data && diff_populate_filespec(r, src, 0))
191                 return 0;
192         if (!dst->cnt_data && diff_populate_filespec(r, dst, 0))
193                 return 0;
194
195         if (diffcore_count_changes(r, src, dst,
196                                    &src->cnt_data, &dst->cnt_data,
197                                    &src_copied, &literal_added))
198                 return 0;
199
200         /* How similar are they?
201          * what percentage of material in dst are from source?
202          */
203         if (!dst->size)
204                 score = 0; /* should not happen */
205         else
206                 score = (int)(src_copied * MAX_SCORE / max_size);
207         return score;
208 }
209
210 static void record_rename_pair(int dst_index, int src_index, int score)
211 {
212         struct diff_filespec *src, *dst;
213         struct diff_filepair *dp;
214
215         if (rename_dst[dst_index].pair)
216                 die("internal error: dst already matched.");
217
218         src = rename_src[src_index].p->one;
219         src->rename_used++;
220         src->count++;
221
222         dst = rename_dst[dst_index].two;
223         dst->count++;
224
225         dp = diff_queue(NULL, src, dst);
226         dp->renamed_pair = 1;
227         if (!strcmp(src->path, dst->path))
228                 dp->score = rename_src[src_index].score;
229         else
230                 dp->score = score;
231         rename_dst[dst_index].pair = dp;
232 }
233
234 /*
235  * We sort the rename similarity matrix with the score, in descending
236  * order (the most similar first).
237  */
238 static int score_compare(const void *a_, const void *b_)
239 {
240         const struct diff_score *a = a_, *b = b_;
241
242         /* sink the unused ones to the bottom */
243         if (a->dst < 0)
244                 return (0 <= b->dst);
245         else if (b->dst < 0)
246                 return -1;
247
248         if (a->score == b->score)
249                 return b->name_score - a->name_score;
250
251         return b->score - a->score;
252 }
253
254 struct file_similarity {
255         struct hashmap_entry entry;
256         int index;
257         struct diff_filespec *filespec;
258 };
259
260 static unsigned int hash_filespec(struct repository *r,
261                                   struct diff_filespec *filespec)
262 {
263         if (!filespec->oid_valid) {
264                 if (diff_populate_filespec(r, filespec, 0))
265                         return 0;
266                 hash_object_file(filespec->data, filespec->size, "blob",
267                                  &filespec->oid);
268         }
269         return oidhash(&filespec->oid);
270 }
271
272 static int find_identical_files(struct hashmap *srcs,
273                                 int dst_index,
274                                 struct diff_options *options)
275 {
276         int renames = 0;
277         struct diff_filespec *target = rename_dst[dst_index].two;
278         struct file_similarity *p, *best = NULL;
279         int i = 100, best_score = -1;
280         unsigned int hash = hash_filespec(options->repo, target);
281
282         /*
283          * Find the best source match for specified destination.
284          */
285         p = hashmap_get_entry_from_hash(srcs, hash, NULL,
286                                         struct file_similarity, entry);
287         hashmap_for_each_entry_from(srcs, p, entry) {
288                 int score;
289                 struct diff_filespec *source = p->filespec;
290
291                 /* False hash collision? */
292                 if (!oideq(&source->oid, &target->oid))
293                         continue;
294                 /* Non-regular files? If so, the modes must match! */
295                 if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
296                         if (source->mode != target->mode)
297                                 continue;
298                 }
299                 /* Give higher scores to sources that haven't been used already */
300                 score = !source->rename_used;
301                 if (source->rename_used && options->detect_rename != DIFF_DETECT_COPY)
302                         continue;
303                 score += basename_same(source, target);
304                 if (score > best_score) {
305                         best = p;
306                         best_score = score;
307                         if (score == 2)
308                                 break;
309                 }
310
311                 /* Too many identical alternatives? Pick one */
312                 if (!--i)
313                         break;
314         }
315         if (best) {
316                 record_rename_pair(dst_index, best->index, MAX_SCORE);
317                 renames++;
318         }
319         return renames;
320 }
321
322 static void insert_file_table(struct repository *r,
323                               struct hashmap *table, int index,
324                               struct diff_filespec *filespec)
325 {
326         struct file_similarity *entry = xmalloc(sizeof(*entry));
327
328         entry->index = index;
329         entry->filespec = filespec;
330
331         hashmap_entry_init(&entry->entry, hash_filespec(r, filespec));
332         hashmap_add(table, &entry->entry);
333 }
334
335 /*
336  * Find exact renames first.
337  *
338  * The first round matches up the up-to-date entries,
339  * and then during the second round we try to match
340  * cache-dirty entries as well.
341  */
342 static int find_exact_renames(struct diff_options *options)
343 {
344         int i, renames = 0;
345         struct hashmap file_table;
346
347         /* Add all sources to the hash table in reverse order, because
348          * later on they will be retrieved in LIFO order.
349          */
350         hashmap_init(&file_table, NULL, NULL, rename_src_nr);
351         for (i = rename_src_nr-1; i >= 0; i--)
352                 insert_file_table(options->repo,
353                                   &file_table, i,
354                                   rename_src[i].p->one);
355
356         /* Walk the destinations and find best source match */
357         for (i = 0; i < rename_dst_nr; i++)
358                 renames += find_identical_files(&file_table, i, options);
359
360         /* Free the hash data structure and entries */
361         hashmap_free_entries(&file_table, struct file_similarity, entry);
362
363         return renames;
364 }
365
366 #define NUM_CANDIDATE_PER_DST 4
367 static void record_if_better(struct diff_score m[], struct diff_score *o)
368 {
369         int i, worst;
370
371         /* find the worst one */
372         worst = 0;
373         for (i = 1; i < NUM_CANDIDATE_PER_DST; i++)
374                 if (score_compare(&m[i], &m[worst]) > 0)
375                         worst = i;
376
377         /* is it better than the worst one? */
378         if (score_compare(&m[worst], o) > 0)
379                 m[worst] = *o;
380 }
381
382 /*
383  * Returns:
384  * 0 if we are under the limit;
385  * 1 if we need to disable inexact rename detection;
386  * 2 if we would be under the limit if we were given -C instead of -C -C.
387  */
388 static int too_many_rename_candidates(int num_create,
389                                       struct diff_options *options)
390 {
391         int rename_limit = options->rename_limit;
392         int num_src = rename_src_nr;
393         int i;
394
395         options->needed_rename_limit = 0;
396
397         /*
398          * This basically does a test for the rename matrix not
399          * growing larger than a "rename_limit" square matrix, ie:
400          *
401          *    num_create * num_src > rename_limit * rename_limit
402          */
403         if (rename_limit <= 0)
404                 rename_limit = 32767;
405         if ((num_create <= rename_limit || num_src <= rename_limit) &&
406             ((uint64_t)num_create * (uint64_t)num_src
407              <= (uint64_t)rename_limit * (uint64_t)rename_limit))
408                 return 0;
409
410         options->needed_rename_limit =
411                 num_src > num_create ? num_src : num_create;
412
413         /* Are we running under -C -C? */
414         if (!options->flags.find_copies_harder)
415                 return 1;
416
417         /* Would we bust the limit if we were running under -C? */
418         for (num_src = i = 0; i < rename_src_nr; i++) {
419                 if (diff_unmodified_pair(rename_src[i].p))
420                         continue;
421                 num_src++;
422         }
423         if ((num_create <= rename_limit || num_src <= rename_limit) &&
424             ((uint64_t)num_create * (uint64_t)num_src
425              <= (uint64_t)rename_limit * (uint64_t)rename_limit))
426                 return 2;
427         return 1;
428 }
429
430 static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, int copies)
431 {
432         int count = 0, i;
433
434         for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
435                 struct diff_rename_dst *dst;
436
437                 if ((mx[i].dst < 0) ||
438                     (mx[i].score < minimum_score))
439                         break; /* there is no more usable pair. */
440                 dst = &rename_dst[mx[i].dst];
441                 if (dst->pair)
442                         continue; /* already done, either exact or fuzzy. */
443                 if (!copies && rename_src[mx[i].src].p->one->rename_used)
444                         continue;
445                 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
446                 count++;
447         }
448         return count;
449 }
450
451 void diffcore_rename(struct diff_options *options)
452 {
453         int detect_rename = options->detect_rename;
454         int minimum_score = options->rename_score;
455         struct diff_queue_struct *q = &diff_queued_diff;
456         struct diff_queue_struct outq;
457         struct diff_score *mx;
458         int i, j, rename_count, skip_unmodified = 0;
459         int num_create, dst_cnt;
460         struct progress *progress = NULL;
461
462         if (!minimum_score)
463                 minimum_score = DEFAULT_RENAME_SCORE;
464
465         for (i = 0; i < q->nr; i++) {
466                 struct diff_filepair *p = q->queue[i];
467                 if (!DIFF_FILE_VALID(p->one)) {
468                         if (!DIFF_FILE_VALID(p->two))
469                                 continue; /* unmerged */
470                         else if (options->single_follow &&
471                                  strcmp(options->single_follow, p->two->path))
472                                 continue; /* not interested */
473                         else if (!options->flags.rename_empty &&
474                                  is_empty_blob_oid(&p->two->oid))
475                                 continue;
476                         else if (add_rename_dst(p->two) < 0) {
477                                 warning("skipping rename detection, detected"
478                                         " duplicate destination '%s'",
479                                         p->two->path);
480                                 goto cleanup;
481                         }
482                 }
483                 else if (!options->flags.rename_empty &&
484                          is_empty_blob_oid(&p->one->oid))
485                         continue;
486                 else if (!DIFF_PAIR_UNMERGED(p) && !DIFF_FILE_VALID(p->two)) {
487                         /*
488                          * If the source is a broken "delete", and
489                          * they did not really want to get broken,
490                          * that means the source actually stays.
491                          * So we increment the "rename_used" score
492                          * by one, to indicate ourselves as a user
493                          */
494                         if (p->broken_pair && !p->score)
495                                 p->one->rename_used++;
496                         register_rename_src(p);
497                 }
498                 else if (detect_rename == DIFF_DETECT_COPY) {
499                         /*
500                          * Increment the "rename_used" score by
501                          * one, to indicate ourselves as a user.
502                          */
503                         p->one->rename_used++;
504                         register_rename_src(p);
505                 }
506         }
507         if (rename_dst_nr == 0 || rename_src_nr == 0)
508                 goto cleanup; /* nothing to do */
509
510         /*
511          * We really want to cull the candidates list early
512          * with cheap tests in order to avoid doing deltas.
513          */
514         rename_count = find_exact_renames(options);
515
516         /* Did we only want exact renames? */
517         if (minimum_score == MAX_SCORE)
518                 goto cleanup;
519
520         /*
521          * Calculate how many renames are left (but all the source
522          * files still remain as options for rename/copies!)
523          */
524         num_create = (rename_dst_nr - rename_count);
525
526         /* All done? */
527         if (!num_create)
528                 goto cleanup;
529
530         switch (too_many_rename_candidates(num_create, options)) {
531         case 1:
532                 goto cleanup;
533         case 2:
534                 options->degraded_cc_to_c = 1;
535                 skip_unmodified = 1;
536                 break;
537         default:
538                 break;
539         }
540
541         if (options->show_rename_progress) {
542                 progress = start_delayed_progress(
543                                 _("Performing inexact rename detection"),
544                                 (uint64_t)rename_dst_nr * (uint64_t)rename_src_nr);
545         }
546
547         mx = xcalloc(st_mult(NUM_CANDIDATE_PER_DST, num_create), sizeof(*mx));
548         for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
549                 struct diff_filespec *two = rename_dst[i].two;
550                 struct diff_score *m;
551
552                 if (rename_dst[i].pair)
553                         continue; /* dealt with exact match already. */
554
555                 m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST];
556                 for (j = 0; j < NUM_CANDIDATE_PER_DST; j++)
557                         m[j].dst = -1;
558
559                 for (j = 0; j < rename_src_nr; j++) {
560                         struct diff_filespec *one = rename_src[j].p->one;
561                         struct diff_score this_src;
562
563                         if (skip_unmodified &&
564                             diff_unmodified_pair(rename_src[j].p))
565                                 continue;
566
567                         this_src.score = estimate_similarity(options->repo,
568                                                              one, two,
569                                                              minimum_score);
570                         this_src.name_score = basename_same(one, two);
571                         this_src.dst = i;
572                         this_src.src = j;
573                         record_if_better(m, &this_src);
574                         /*
575                          * Once we run estimate_similarity,
576                          * We do not need the text anymore.
577                          */
578                         diff_free_filespec_blob(one);
579                         diff_free_filespec_blob(two);
580                 }
581                 dst_cnt++;
582                 display_progress(progress, (uint64_t)(i+1)*(uint64_t)rename_src_nr);
583         }
584         stop_progress(&progress);
585
586         /* cost matrix sorted by most to least similar pair */
587         STABLE_QSORT(mx, dst_cnt * NUM_CANDIDATE_PER_DST, score_compare);
588
589         rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
590         if (detect_rename == DIFF_DETECT_COPY)
591                 rename_count += find_renames(mx, dst_cnt, minimum_score, 1);
592         free(mx);
593
594  cleanup:
595         /* At this point, we have found some renames and copies and they
596          * are recorded in rename_dst.  The original list is still in *q.
597          */
598         DIFF_QUEUE_CLEAR(&outq);
599         for (i = 0; i < q->nr; i++) {
600                 struct diff_filepair *p = q->queue[i];
601                 struct diff_filepair *pair_to_free = NULL;
602
603                 if (DIFF_PAIR_UNMERGED(p)) {
604                         diff_q(&outq, p);
605                 }
606                 else if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
607                         /*
608                          * Creation
609                          *
610                          * We would output this create record if it has
611                          * not been turned into a rename/copy already.
612                          */
613                         struct diff_rename_dst *dst = locate_rename_dst(p->two);
614                         if (dst && dst->pair) {
615                                 diff_q(&outq, dst->pair);
616                                 pair_to_free = p;
617                         }
618                         else
619                                 /* no matching rename/copy source, so
620                                  * record this as a creation.
621                                  */
622                                 diff_q(&outq, p);
623                 }
624                 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
625                         /*
626                          * Deletion
627                          *
628                          * We would output this delete record if:
629                          *
630                          * (1) this is a broken delete and the counterpart
631                          *     broken create remains in the output; or
632                          * (2) this is not a broken delete, and rename_dst
633                          *     does not have a rename/copy to move p->one->path
634                          *     out of existence.
635                          *
636                          * Otherwise, the counterpart broken create
637                          * has been turned into a rename-edit; or
638                          * delete did not have a matching create to
639                          * begin with.
640                          */
641                         if (DIFF_PAIR_BROKEN(p)) {
642                                 /* broken delete */
643                                 struct diff_rename_dst *dst = locate_rename_dst(p->one);
644                                 if (dst && dst->pair)
645                                         /* counterpart is now rename/copy */
646                                         pair_to_free = p;
647                         }
648                         else {
649                                 if (p->one->rename_used)
650                                         /* this path remains */
651                                         pair_to_free = p;
652                         }
653
654                         if (pair_to_free)
655                                 ;
656                         else
657                                 diff_q(&outq, p);
658                 }
659                 else if (!diff_unmodified_pair(p))
660                         /* all the usual ones need to be kept */
661                         diff_q(&outq, p);
662                 else
663                         /* no need to keep unmodified pairs */
664                         pair_to_free = p;
665
666                 if (pair_to_free)
667                         diff_free_filepair(pair_to_free);
668         }
669         diff_debug_queue("done copying original", &outq);
670
671         free(q->queue);
672         *q = outq;
673         diff_debug_queue("done collapsing", q);
674
675         for (i = 0; i < rename_dst_nr; i++)
676                 free_filespec(rename_dst[i].two);
677
678         FREE_AND_NULL(rename_dst);
679         rename_dst_nr = rename_dst_alloc = 0;
680         FREE_AND_NULL(rename_src);
681         rename_src_nr = rename_src_alloc = 0;
682         return;
683 }