Merge branch 'bp/test-drop-caches-for-windows'
[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 = (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 = (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 diff_filespec *src,
132                                struct diff_filespec *dst,
133                                int minimum_score)
134 {
135         /* src points at a file that existed in the original tree (or
136          * optionally a file in the destination tree) and dst points
137          * at a newly created file.  They may be quite similar, in which
138          * case we want to say src is renamed to dst or src is copied into
139          * dst, and then some edit has been applied to dst.
140          *
141          * Compare them and return how similar they are, representing
142          * the score as an integer between 0 and MAX_SCORE.
143          *
144          * When there is an exact match, it is considered a better
145          * match than anything else; the destination does not even
146          * call into this function in that case.
147          */
148         unsigned long max_size, delta_size, base_size, src_copied, literal_added;
149         int score;
150
151         /* We deal only with regular files.  Symlink renames are handled
152          * only when they are exact matches --- in other words, no edits
153          * after renaming.
154          */
155         if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
156                 return 0;
157
158         /*
159          * Need to check that source and destination sizes are
160          * filled in before comparing them.
161          *
162          * If we already have "cnt_data" filled in, we know it's
163          * all good (avoid checking the size for zero, as that
164          * is a possible size - we really should have a flag to
165          * say whether the size is valid or not!)
166          */
167         if (!src->cnt_data &&
168             diff_populate_filespec(src, CHECK_SIZE_ONLY))
169                 return 0;
170         if (!dst->cnt_data &&
171             diff_populate_filespec(dst, CHECK_SIZE_ONLY))
172                 return 0;
173
174         max_size = ((src->size > dst->size) ? src->size : dst->size);
175         base_size = ((src->size < dst->size) ? src->size : dst->size);
176         delta_size = max_size - base_size;
177
178         /* We would not consider edits that change the file size so
179          * drastically.  delta_size must be smaller than
180          * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
181          *
182          * Note that base_size == 0 case is handled here already
183          * and the final score computation below would not have a
184          * divide-by-zero issue.
185          */
186         if (max_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
187                 return 0;
188
189         if (!src->cnt_data && diff_populate_filespec(src, 0))
190                 return 0;
191         if (!dst->cnt_data && diff_populate_filespec(dst, 0))
192                 return 0;
193
194         if (diffcore_count_changes(src, dst,
195                                    &src->cnt_data, &dst->cnt_data,
196                                    &src_copied, &literal_added))
197                 return 0;
198
199         /* How similar are they?
200          * what percentage of material in dst are from source?
201          */
202         if (!dst->size)
203                 score = 0; /* should not happen */
204         else
205                 score = (int)(src_copied * MAX_SCORE / max_size);
206         return score;
207 }
208
209 static void record_rename_pair(int dst_index, int src_index, int score)
210 {
211         struct diff_filespec *src, *dst;
212         struct diff_filepair *dp;
213
214         if (rename_dst[dst_index].pair)
215                 die("internal error: dst already matched.");
216
217         src = rename_src[src_index].p->one;
218         src->rename_used++;
219         src->count++;
220
221         dst = rename_dst[dst_index].two;
222         dst->count++;
223
224         dp = diff_queue(NULL, src, dst);
225         dp->renamed_pair = 1;
226         if (!strcmp(src->path, dst->path))
227                 dp->score = rename_src[src_index].score;
228         else
229                 dp->score = score;
230         rename_dst[dst_index].pair = dp;
231 }
232
233 /*
234  * We sort the rename similarity matrix with the score, in descending
235  * order (the most similar first).
236  */
237 static int score_compare(const void *a_, const void *b_)
238 {
239         const struct diff_score *a = a_, *b = b_;
240
241         /* sink the unused ones to the bottom */
242         if (a->dst < 0)
243                 return (0 <= b->dst);
244         else if (b->dst < 0)
245                 return -1;
246
247         if (a->score == b->score)
248                 return b->name_score - a->name_score;
249
250         return b->score - a->score;
251 }
252
253 struct file_similarity {
254         struct hashmap_entry entry;
255         int index;
256         struct diff_filespec *filespec;
257 };
258
259 static unsigned int hash_filespec(struct diff_filespec *filespec)
260 {
261         if (!filespec->oid_valid) {
262                 if (diff_populate_filespec(filespec, 0))
263                         return 0;
264                 hash_object_file(filespec->data, filespec->size, "blob",
265                                  &filespec->oid);
266         }
267         return sha1hash(filespec->oid.hash);
268 }
269
270 static int find_identical_files(struct hashmap *srcs,
271                                 int dst_index,
272                                 struct diff_options *options)
273 {
274         int renames = 0;
275
276         struct diff_filespec *target = rename_dst[dst_index].two;
277         struct file_similarity *p, *best = NULL;
278         int i = 100, best_score = -1;
279
280         /*
281          * Find the best source match for specified destination.
282          */
283         p = hashmap_get_from_hash(srcs, hash_filespec(target), NULL);
284         for (; p; p = hashmap_get_next(srcs, p)) {
285                 int score;
286                 struct diff_filespec *source = p->filespec;
287
288                 /* False hash collision? */
289                 if (oidcmp(&source->oid, &target->oid))
290                         continue;
291                 /* Non-regular files? If so, the modes must match! */
292                 if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
293                         if (source->mode != target->mode)
294                                 continue;
295                 }
296                 /* Give higher scores to sources that haven't been used already */
297                 score = !source->rename_used;
298                 if (source->rename_used && options->detect_rename != DIFF_DETECT_COPY)
299                         continue;
300                 score += basename_same(source, target);
301                 if (score > best_score) {
302                         best = p;
303                         best_score = score;
304                         if (score == 2)
305                                 break;
306                 }
307
308                 /* Too many identical alternatives? Pick one */
309                 if (!--i)
310                         break;
311         }
312         if (best) {
313                 record_rename_pair(dst_index, best->index, MAX_SCORE);
314                 renames++;
315         }
316         return renames;
317 }
318
319 static void insert_file_table(struct hashmap *table, int index, struct diff_filespec *filespec)
320 {
321         struct file_similarity *entry = xmalloc(sizeof(*entry));
322
323         entry->index = index;
324         entry->filespec = filespec;
325
326         hashmap_entry_init(entry, hash_filespec(filespec));
327         hashmap_add(table, entry);
328 }
329
330 /*
331  * Find exact renames first.
332  *
333  * The first round matches up the up-to-date entries,
334  * and then during the second round we try to match
335  * cache-dirty entries as well.
336  */
337 static int find_exact_renames(struct diff_options *options)
338 {
339         int i, renames = 0;
340         struct hashmap file_table;
341
342         /* Add all sources to the hash table in reverse order, because
343          * later on they will be retrieved in LIFO order.
344          */
345         hashmap_init(&file_table, NULL, NULL, rename_src_nr);
346         for (i = rename_src_nr-1; i >= 0; i--)
347                 insert_file_table(&file_table, i, rename_src[i].p->one);
348
349         /* Walk the destinations and find best source match */
350         for (i = 0; i < rename_dst_nr; i++)
351                 renames += find_identical_files(&file_table, i, options);
352
353         /* Free the hash data structure and entries */
354         hashmap_free(&file_table, 1);
355
356         return renames;
357 }
358
359 #define NUM_CANDIDATE_PER_DST 4
360 static void record_if_better(struct diff_score m[], struct diff_score *o)
361 {
362         int i, worst;
363
364         /* find the worst one */
365         worst = 0;
366         for (i = 1; i < NUM_CANDIDATE_PER_DST; i++)
367                 if (score_compare(&m[i], &m[worst]) > 0)
368                         worst = i;
369
370         /* is it better than the worst one? */
371         if (score_compare(&m[worst], o) > 0)
372                 m[worst] = *o;
373 }
374
375 /*
376  * Returns:
377  * 0 if we are under the limit;
378  * 1 if we need to disable inexact rename detection;
379  * 2 if we would be under the limit if we were given -C instead of -C -C.
380  */
381 static int too_many_rename_candidates(int num_create,
382                                       struct diff_options *options)
383 {
384         int rename_limit = options->rename_limit;
385         int num_src = rename_src_nr;
386         int i;
387
388         options->needed_rename_limit = 0;
389
390         /*
391          * This basically does a test for the rename matrix not
392          * growing larger than a "rename_limit" square matrix, ie:
393          *
394          *    num_create * num_src > rename_limit * rename_limit
395          */
396         if (rename_limit <= 0)
397                 rename_limit = 32767;
398         if ((num_create <= rename_limit || num_src <= rename_limit) &&
399             ((uint64_t)num_create * (uint64_t)num_src
400              <= (uint64_t)rename_limit * (uint64_t)rename_limit))
401                 return 0;
402
403         options->needed_rename_limit =
404                 num_src > num_create ? num_src : num_create;
405
406         /* Are we running under -C -C? */
407         if (!options->flags.find_copies_harder)
408                 return 1;
409
410         /* Would we bust the limit if we were running under -C? */
411         for (num_src = i = 0; i < rename_src_nr; i++) {
412                 if (diff_unmodified_pair(rename_src[i].p))
413                         continue;
414                 num_src++;
415         }
416         if ((num_create <= rename_limit || num_src <= rename_limit) &&
417             ((uint64_t)num_create * (uint64_t)num_src
418              <= (uint64_t)rename_limit * (uint64_t)rename_limit))
419                 return 2;
420         return 1;
421 }
422
423 static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, int copies)
424 {
425         int count = 0, i;
426
427         for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
428                 struct diff_rename_dst *dst;
429
430                 if ((mx[i].dst < 0) ||
431                     (mx[i].score < minimum_score))
432                         break; /* there is no more usable pair. */
433                 dst = &rename_dst[mx[i].dst];
434                 if (dst->pair)
435                         continue; /* already done, either exact or fuzzy. */
436                 if (!copies && rename_src[mx[i].src].p->one->rename_used)
437                         continue;
438                 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
439                 count++;
440         }
441         return count;
442 }
443
444 void diffcore_rename(struct diff_options *options)
445 {
446         int detect_rename = options->detect_rename;
447         int minimum_score = options->rename_score;
448         struct diff_queue_struct *q = &diff_queued_diff;
449         struct diff_queue_struct outq;
450         struct diff_score *mx;
451         int i, j, rename_count, skip_unmodified = 0;
452         int num_create, dst_cnt;
453         struct progress *progress = NULL;
454
455         if (!minimum_score)
456                 minimum_score = DEFAULT_RENAME_SCORE;
457
458         for (i = 0; i < q->nr; i++) {
459                 struct diff_filepair *p = q->queue[i];
460                 if (!DIFF_FILE_VALID(p->one)) {
461                         if (!DIFF_FILE_VALID(p->two))
462                                 continue; /* unmerged */
463                         else if (options->single_follow &&
464                                  strcmp(options->single_follow, p->two->path))
465                                 continue; /* not interested */
466                         else if (!options->flags.rename_empty &&
467                                  is_empty_blob_oid(&p->two->oid))
468                                 continue;
469                         else if (add_rename_dst(p->two) < 0) {
470                                 warning("skipping rename detection, detected"
471                                         " duplicate destination '%s'",
472                                         p->two->path);
473                                 goto cleanup;
474                         }
475                 }
476                 else if (!options->flags.rename_empty &&
477                          is_empty_blob_oid(&p->one->oid))
478                         continue;
479                 else if (!DIFF_PAIR_UNMERGED(p) && !DIFF_FILE_VALID(p->two)) {
480                         /*
481                          * If the source is a broken "delete", and
482                          * they did not really want to get broken,
483                          * that means the source actually stays.
484                          * So we increment the "rename_used" score
485                          * by one, to indicate ourselves as a user
486                          */
487                         if (p->broken_pair && !p->score)
488                                 p->one->rename_used++;
489                         register_rename_src(p);
490                 }
491                 else if (detect_rename == DIFF_DETECT_COPY) {
492                         /*
493                          * Increment the "rename_used" score by
494                          * one, to indicate ourselves as a user.
495                          */
496                         p->one->rename_used++;
497                         register_rename_src(p);
498                 }
499         }
500         if (rename_dst_nr == 0 || rename_src_nr == 0)
501                 goto cleanup; /* nothing to do */
502
503         /*
504          * We really want to cull the candidates list early
505          * with cheap tests in order to avoid doing deltas.
506          */
507         rename_count = find_exact_renames(options);
508
509         /* Did we only want exact renames? */
510         if (minimum_score == MAX_SCORE)
511                 goto cleanup;
512
513         /*
514          * Calculate how many renames are left (but all the source
515          * files still remain as options for rename/copies!)
516          */
517         num_create = (rename_dst_nr - rename_count);
518
519         /* All done? */
520         if (!num_create)
521                 goto cleanup;
522
523         switch (too_many_rename_candidates(num_create, options)) {
524         case 1:
525                 goto cleanup;
526         case 2:
527                 options->degraded_cc_to_c = 1;
528                 skip_unmodified = 1;
529                 break;
530         default:
531                 break;
532         }
533
534         if (options->show_rename_progress) {
535                 progress = start_delayed_progress(
536                                 _("Performing inexact rename detection"),
537                                 (uint64_t)rename_dst_nr * (uint64_t)rename_src_nr);
538         }
539
540         mx = xcalloc(st_mult(NUM_CANDIDATE_PER_DST, num_create), sizeof(*mx));
541         for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
542                 struct diff_filespec *two = rename_dst[i].two;
543                 struct diff_score *m;
544
545                 if (rename_dst[i].pair)
546                         continue; /* dealt with exact match already. */
547
548                 m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST];
549                 for (j = 0; j < NUM_CANDIDATE_PER_DST; j++)
550                         m[j].dst = -1;
551
552                 for (j = 0; j < rename_src_nr; j++) {
553                         struct diff_filespec *one = rename_src[j].p->one;
554                         struct diff_score this_src;
555
556                         if (skip_unmodified &&
557                             diff_unmodified_pair(rename_src[j].p))
558                                 continue;
559
560                         this_src.score = estimate_similarity(one, two,
561                                                              minimum_score);
562                         this_src.name_score = basename_same(one, two);
563                         this_src.dst = i;
564                         this_src.src = j;
565                         record_if_better(m, &this_src);
566                         /*
567                          * Once we run estimate_similarity,
568                          * We do not need the text anymore.
569                          */
570                         diff_free_filespec_blob(one);
571                         diff_free_filespec_blob(two);
572                 }
573                 dst_cnt++;
574                 display_progress(progress, (uint64_t)(i+1)*(uint64_t)rename_src_nr);
575         }
576         stop_progress(&progress);
577
578         /* cost matrix sorted by most to least similar pair */
579         QSORT(mx, dst_cnt * NUM_CANDIDATE_PER_DST, score_compare);
580
581         rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
582         if (detect_rename == DIFF_DETECT_COPY)
583                 rename_count += find_renames(mx, dst_cnt, minimum_score, 1);
584         free(mx);
585
586  cleanup:
587         /* At this point, we have found some renames and copies and they
588          * are recorded in rename_dst.  The original list is still in *q.
589          */
590         DIFF_QUEUE_CLEAR(&outq);
591         for (i = 0; i < q->nr; i++) {
592                 struct diff_filepair *p = q->queue[i];
593                 struct diff_filepair *pair_to_free = NULL;
594
595                 if (DIFF_PAIR_UNMERGED(p)) {
596                         diff_q(&outq, p);
597                 }
598                 else if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
599                         /*
600                          * Creation
601                          *
602                          * We would output this create record if it has
603                          * not been turned into a rename/copy already.
604                          */
605                         struct diff_rename_dst *dst = locate_rename_dst(p->two);
606                         if (dst && dst->pair) {
607                                 diff_q(&outq, dst->pair);
608                                 pair_to_free = p;
609                         }
610                         else
611                                 /* no matching rename/copy source, so
612                                  * record this as a creation.
613                                  */
614                                 diff_q(&outq, p);
615                 }
616                 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
617                         /*
618                          * Deletion
619                          *
620                          * We would output this delete record if:
621                          *
622                          * (1) this is a broken delete and the counterpart
623                          *     broken create remains in the output; or
624                          * (2) this is not a broken delete, and rename_dst
625                          *     does not have a rename/copy to move p->one->path
626                          *     out of existence.
627                          *
628                          * Otherwise, the counterpart broken create
629                          * has been turned into a rename-edit; or
630                          * delete did not have a matching create to
631                          * begin with.
632                          */
633                         if (DIFF_PAIR_BROKEN(p)) {
634                                 /* broken delete */
635                                 struct diff_rename_dst *dst = locate_rename_dst(p->one);
636                                 if (dst && dst->pair)
637                                         /* counterpart is now rename/copy */
638                                         pair_to_free = p;
639                         }
640                         else {
641                                 if (p->one->rename_used)
642                                         /* this path remains */
643                                         pair_to_free = p;
644                         }
645
646                         if (pair_to_free)
647                                 ;
648                         else
649                                 diff_q(&outq, p);
650                 }
651                 else if (!diff_unmodified_pair(p))
652                         /* all the usual ones need to be kept */
653                         diff_q(&outq, p);
654                 else
655                         /* no need to keep unmodified pairs */
656                         pair_to_free = p;
657
658                 if (pair_to_free)
659                         diff_free_filepair(pair_to_free);
660         }
661         diff_debug_queue("done copying original", &outq);
662
663         free(q->queue);
664         *q = outq;
665         diff_debug_queue("done collapsing", q);
666
667         for (i = 0; i < rename_dst_nr; i++)
668                 free_filespec(rename_dst[i].two);
669
670         FREE_AND_NULL(rename_dst);
671         rename_dst_nr = rename_dst_alloc = 0;
672         FREE_AND_NULL(rename_src);
673         rename_src_nr = rename_src_alloc = 0;
674         return;
675 }