Merge branch 'jk/prune-packed-server-info'
[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 "hashmap.h"
8 #include "progress.h"
9
10 /* Table of rename/copy destinations */
11
12 static struct diff_rename_dst {
13         struct diff_filespec *two;
14         struct diff_filepair *pair;
15 } *rename_dst;
16 static int rename_dst_nr, rename_dst_alloc;
17
18 static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
19                                                  int insert_ok)
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 dst;
31                 if (cmp < 0) {
32                         last = next;
33                         continue;
34                 }
35                 first = next+1;
36         }
37         /* not found */
38         if (!insert_ok)
39                 return NULL;
40         /* insert to make it at "first" */
41         ALLOC_GROW(rename_dst, rename_dst_nr + 1, rename_dst_alloc);
42         rename_dst_nr++;
43         if (first < rename_dst_nr)
44                 memmove(rename_dst + first + 1, rename_dst + first,
45                         (rename_dst_nr - first - 1) * sizeof(*rename_dst));
46         rename_dst[first].two = alloc_filespec(two->path);
47         fill_filespec(rename_dst[first].two, two->sha1, two->sha1_valid, two->mode);
48         rename_dst[first].pair = NULL;
49         return &(rename_dst[first]);
50 }
51
52 /* Table of rename/copy src files */
53 static struct diff_rename_src {
54         struct diff_filepair *p;
55         unsigned short score; /* to remember the break score */
56 } *rename_src;
57 static int rename_src_nr, rename_src_alloc;
58
59 static struct diff_rename_src *register_rename_src(struct diff_filepair *p)
60 {
61         int first, last;
62         struct diff_filespec *one = p->one;
63         unsigned short score = p->score;
64
65         first = 0;
66         last = rename_src_nr;
67         while (last > first) {
68                 int next = (last + first) >> 1;
69                 struct diff_rename_src *src = &(rename_src[next]);
70                 int cmp = strcmp(one->path, src->p->one->path);
71                 if (!cmp)
72                         return src;
73                 if (cmp < 0) {
74                         last = next;
75                         continue;
76                 }
77                 first = next+1;
78         }
79
80         /* insert to make it at "first" */
81         ALLOC_GROW(rename_src, rename_src_nr + 1, rename_src_alloc);
82         rename_src_nr++;
83         if (first < rename_src_nr)
84                 memmove(rename_src + first + 1, rename_src + first,
85                         (rename_src_nr - first - 1) * sizeof(*rename_src));
86         rename_src[first].p = p;
87         rename_src[first].score = score;
88         return &(rename_src[first]);
89 }
90
91 static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
92 {
93         int src_len = strlen(src->path), dst_len = strlen(dst->path);
94         while (src_len && dst_len) {
95                 char c1 = src->path[--src_len];
96                 char c2 = dst->path[--dst_len];
97                 if (c1 != c2)
98                         return 0;
99                 if (c1 == '/')
100                         return 1;
101         }
102         return (!src_len || src->path[src_len - 1] == '/') &&
103                 (!dst_len || dst->path[dst_len - 1] == '/');
104 }
105
106 struct diff_score {
107         int src; /* index in rename_src */
108         int dst; /* index in rename_dst */
109         unsigned short score;
110         short name_score;
111 };
112
113 static int estimate_similarity(struct diff_filespec *src,
114                                struct diff_filespec *dst,
115                                int minimum_score)
116 {
117         /* src points at a file that existed in the original tree (or
118          * optionally a file in the destination tree) and dst points
119          * at a newly created file.  They may be quite similar, in which
120          * case we want to say src is renamed to dst or src is copied into
121          * dst, and then some edit has been applied to dst.
122          *
123          * Compare them and return how similar they are, representing
124          * the score as an integer between 0 and MAX_SCORE.
125          *
126          * When there is an exact match, it is considered a better
127          * match than anything else; the destination does not even
128          * call into this function in that case.
129          */
130         unsigned long max_size, delta_size, base_size, src_copied, literal_added;
131         unsigned long delta_limit;
132         int score;
133
134         /* We deal only with regular files.  Symlink renames are handled
135          * only when they are exact matches --- in other words, no edits
136          * after renaming.
137          */
138         if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
139                 return 0;
140
141         /*
142          * Need to check that source and destination sizes are
143          * filled in before comparing them.
144          *
145          * If we already have "cnt_data" filled in, we know it's
146          * all good (avoid checking the size for zero, as that
147          * is a possible size - we really should have a flag to
148          * say whether the size is valid or not!)
149          */
150         if (!src->cnt_data &&
151             diff_populate_filespec(src, CHECK_SIZE_ONLY))
152                 return 0;
153         if (!dst->cnt_data &&
154             diff_populate_filespec(dst, CHECK_SIZE_ONLY))
155                 return 0;
156
157         max_size = ((src->size > dst->size) ? src->size : dst->size);
158         base_size = ((src->size < dst->size) ? src->size : dst->size);
159         delta_size = max_size - base_size;
160
161         /* We would not consider edits that change the file size so
162          * drastically.  delta_size must be smaller than
163          * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
164          *
165          * Note that base_size == 0 case is handled here already
166          * and the final score computation below would not have a
167          * divide-by-zero issue.
168          */
169         if (max_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
170                 return 0;
171
172         if (!src->cnt_data && diff_populate_filespec(src, 0))
173                 return 0;
174         if (!dst->cnt_data && diff_populate_filespec(dst, 0))
175                 return 0;
176
177         delta_limit = (unsigned long)
178                 (base_size * (MAX_SCORE-minimum_score) / MAX_SCORE);
179         if (diffcore_count_changes(src, dst,
180                                    &src->cnt_data, &dst->cnt_data,
181                                    delta_limit,
182                                    &src_copied, &literal_added))
183                 return 0;
184
185         /* How similar are they?
186          * what percentage of material in dst are from source?
187          */
188         if (!dst->size)
189                 score = 0; /* should not happen */
190         else
191                 score = (int)(src_copied * MAX_SCORE / max_size);
192         return score;
193 }
194
195 static void record_rename_pair(int dst_index, int src_index, int score)
196 {
197         struct diff_filespec *src, *dst;
198         struct diff_filepair *dp;
199
200         if (rename_dst[dst_index].pair)
201                 die("internal error: dst already matched.");
202
203         src = rename_src[src_index].p->one;
204         src->rename_used++;
205         src->count++;
206
207         dst = rename_dst[dst_index].two;
208         dst->count++;
209
210         dp = diff_queue(NULL, src, dst);
211         dp->renamed_pair = 1;
212         if (!strcmp(src->path, dst->path))
213                 dp->score = rename_src[src_index].score;
214         else
215                 dp->score = score;
216         rename_dst[dst_index].pair = dp;
217 }
218
219 /*
220  * We sort the rename similarity matrix with the score, in descending
221  * order (the most similar first).
222  */
223 static int score_compare(const void *a_, const void *b_)
224 {
225         const struct diff_score *a = a_, *b = b_;
226
227         /* sink the unused ones to the bottom */
228         if (a->dst < 0)
229                 return (0 <= b->dst);
230         else if (b->dst < 0)
231                 return -1;
232
233         if (a->score == b->score)
234                 return b->name_score - a->name_score;
235
236         return b->score - a->score;
237 }
238
239 struct file_similarity {
240         struct hashmap_entry entry;
241         int index;
242         struct diff_filespec *filespec;
243 };
244
245 static unsigned int hash_filespec(struct diff_filespec *filespec)
246 {
247         if (!filespec->sha1_valid) {
248                 if (diff_populate_filespec(filespec, 0))
249                         return 0;
250                 hash_sha1_file(filespec->data, filespec->size, "blob", filespec->sha1);
251         }
252         return sha1hash(filespec->sha1);
253 }
254
255 static int find_identical_files(struct hashmap *srcs,
256                                 int dst_index,
257                                 struct diff_options *options)
258 {
259         int renames = 0;
260
261         struct diff_filespec *target = rename_dst[dst_index].two;
262         struct file_similarity *p, *best = NULL;
263         int i = 100, best_score = -1;
264
265         /*
266          * Find the best source match for specified destination.
267          */
268         p = hashmap_get_from_hash(srcs, hash_filespec(target), NULL);
269         for (; p; p = hashmap_get_next(srcs, p)) {
270                 int score;
271                 struct diff_filespec *source = p->filespec;
272
273                 /* False hash collision? */
274                 if (hashcmp(source->sha1, target->sha1))
275                         continue;
276                 /* Non-regular files? If so, the modes must match! */
277                 if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
278                         if (source->mode != target->mode)
279                                 continue;
280                 }
281                 /* Give higher scores to sources that haven't been used already */
282                 score = !source->rename_used;
283                 if (source->rename_used && options->detect_rename != DIFF_DETECT_COPY)
284                         continue;
285                 score += basename_same(source, target);
286                 if (score > best_score) {
287                         best = p;
288                         best_score = score;
289                         if (score == 2)
290                                 break;
291                 }
292
293                 /* Too many identical alternatives? Pick one */
294                 if (!--i)
295                         break;
296         }
297         if (best) {
298                 record_rename_pair(dst_index, best->index, MAX_SCORE);
299                 renames++;
300         }
301         return renames;
302 }
303
304 static void insert_file_table(struct hashmap *table, int index, struct diff_filespec *filespec)
305 {
306         struct file_similarity *entry = xmalloc(sizeof(*entry));
307
308         entry->index = index;
309         entry->filespec = filespec;
310
311         hashmap_entry_init(entry, hash_filespec(filespec));
312         hashmap_add(table, entry);
313 }
314
315 /*
316  * Find exact renames first.
317  *
318  * The first round matches up the up-to-date entries,
319  * and then during the second round we try to match
320  * cache-dirty entries as well.
321  */
322 static int find_exact_renames(struct diff_options *options)
323 {
324         int i, renames = 0;
325         struct hashmap file_table;
326
327         /* Add all sources to the hash table */
328         hashmap_init(&file_table, NULL, rename_src_nr);
329         for (i = 0; i < rename_src_nr; i++)
330                 insert_file_table(&file_table, i, rename_src[i].p->one);
331
332         /* Walk the destinations and find best source match */
333         for (i = 0; i < rename_dst_nr; i++)
334                 renames += find_identical_files(&file_table, i, options);
335
336         /* Free the hash data structure and entries */
337         hashmap_free(&file_table, 1);
338
339         return renames;
340 }
341
342 #define NUM_CANDIDATE_PER_DST 4
343 static void record_if_better(struct diff_score m[], struct diff_score *o)
344 {
345         int i, worst;
346
347         /* find the worst one */
348         worst = 0;
349         for (i = 1; i < NUM_CANDIDATE_PER_DST; i++)
350                 if (score_compare(&m[i], &m[worst]) > 0)
351                         worst = i;
352
353         /* is it better than the worst one? */
354         if (score_compare(&m[worst], o) > 0)
355                 m[worst] = *o;
356 }
357
358 /*
359  * Returns:
360  * 0 if we are under the limit;
361  * 1 if we need to disable inexact rename detection;
362  * 2 if we would be under the limit if we were given -C instead of -C -C.
363  */
364 static int too_many_rename_candidates(int num_create,
365                                       struct diff_options *options)
366 {
367         int rename_limit = options->rename_limit;
368         int num_src = rename_src_nr;
369         int i;
370
371         options->needed_rename_limit = 0;
372
373         /*
374          * This basically does a test for the rename matrix not
375          * growing larger than a "rename_limit" square matrix, ie:
376          *
377          *    num_create * num_src > rename_limit * rename_limit
378          *
379          * but handles the potential overflow case specially (and we
380          * assume at least 32-bit integers)
381          */
382         if (rename_limit <= 0 || rename_limit > 32767)
383                 rename_limit = 32767;
384         if ((num_create <= rename_limit || num_src <= rename_limit) &&
385             (num_create * num_src <= rename_limit * rename_limit))
386                 return 0;
387
388         options->needed_rename_limit =
389                 num_src > num_create ? num_src : num_create;
390
391         /* Are we running under -C -C? */
392         if (!DIFF_OPT_TST(options, FIND_COPIES_HARDER))
393                 return 1;
394
395         /* Would we bust the limit if we were running under -C? */
396         for (num_src = i = 0; i < rename_src_nr; i++) {
397                 if (diff_unmodified_pair(rename_src[i].p))
398                         continue;
399                 num_src++;
400         }
401         if ((num_create <= rename_limit || num_src <= rename_limit) &&
402             (num_create * num_src <= rename_limit * rename_limit))
403                 return 2;
404         return 1;
405 }
406
407 static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, int copies)
408 {
409         int count = 0, i;
410
411         for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
412                 struct diff_rename_dst *dst;
413
414                 if ((mx[i].dst < 0) ||
415                     (mx[i].score < minimum_score))
416                         break; /* there is no more usable pair. */
417                 dst = &rename_dst[mx[i].dst];
418                 if (dst->pair)
419                         continue; /* already done, either exact or fuzzy. */
420                 if (!copies && rename_src[mx[i].src].p->one->rename_used)
421                         continue;
422                 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
423                 count++;
424         }
425         return count;
426 }
427
428 void diffcore_rename(struct diff_options *options)
429 {
430         int detect_rename = options->detect_rename;
431         int minimum_score = options->rename_score;
432         struct diff_queue_struct *q = &diff_queued_diff;
433         struct diff_queue_struct outq;
434         struct diff_score *mx;
435         int i, j, rename_count, skip_unmodified = 0;
436         int num_create, dst_cnt;
437         struct progress *progress = NULL;
438
439         if (!minimum_score)
440                 minimum_score = DEFAULT_RENAME_SCORE;
441
442         for (i = 0; i < q->nr; i++) {
443                 struct diff_filepair *p = q->queue[i];
444                 if (!DIFF_FILE_VALID(p->one)) {
445                         if (!DIFF_FILE_VALID(p->two))
446                                 continue; /* unmerged */
447                         else if (options->single_follow &&
448                                  strcmp(options->single_follow, p->two->path))
449                                 continue; /* not interested */
450                         else if (!DIFF_OPT_TST(options, RENAME_EMPTY) &&
451                                  is_empty_blob_sha1(p->two->sha1))
452                                 continue;
453                         else
454                                 locate_rename_dst(p->two, 1);
455                 }
456                 else if (!DIFF_OPT_TST(options, RENAME_EMPTY) &&
457                          is_empty_blob_sha1(p->one->sha1))
458                         continue;
459                 else if (!DIFF_PAIR_UNMERGED(p) && !DIFF_FILE_VALID(p->two)) {
460                         /*
461                          * If the source is a broken "delete", and
462                          * they did not really want to get broken,
463                          * that means the source actually stays.
464                          * So we increment the "rename_used" score
465                          * by one, to indicate ourselves as a user
466                          */
467                         if (p->broken_pair && !p->score)
468                                 p->one->rename_used++;
469                         register_rename_src(p);
470                 }
471                 else if (detect_rename == DIFF_DETECT_COPY) {
472                         /*
473                          * Increment the "rename_used" score by
474                          * one, to indicate ourselves as a user.
475                          */
476                         p->one->rename_used++;
477                         register_rename_src(p);
478                 }
479         }
480         if (rename_dst_nr == 0 || rename_src_nr == 0)
481                 goto cleanup; /* nothing to do */
482
483         /*
484          * We really want to cull the candidates list early
485          * with cheap tests in order to avoid doing deltas.
486          */
487         rename_count = find_exact_renames(options);
488
489         /* Did we only want exact renames? */
490         if (minimum_score == MAX_SCORE)
491                 goto cleanup;
492
493         /*
494          * Calculate how many renames are left (but all the source
495          * files still remain as options for rename/copies!)
496          */
497         num_create = (rename_dst_nr - rename_count);
498
499         /* All done? */
500         if (!num_create)
501                 goto cleanup;
502
503         switch (too_many_rename_candidates(num_create, options)) {
504         case 1:
505                 goto cleanup;
506         case 2:
507                 options->degraded_cc_to_c = 1;
508                 skip_unmodified = 1;
509                 break;
510         default:
511                 break;
512         }
513
514         if (options->show_rename_progress) {
515                 progress = start_progress_delay(
516                                 _("Performing inexact rename detection"),
517                                 rename_dst_nr * rename_src_nr, 50, 1);
518         }
519
520         mx = xcalloc(num_create * NUM_CANDIDATE_PER_DST, sizeof(*mx));
521         for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
522                 struct diff_filespec *two = rename_dst[i].two;
523                 struct diff_score *m;
524
525                 if (rename_dst[i].pair)
526                         continue; /* dealt with exact match already. */
527
528                 m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST];
529                 for (j = 0; j < NUM_CANDIDATE_PER_DST; j++)
530                         m[j].dst = -1;
531
532                 for (j = 0; j < rename_src_nr; j++) {
533                         struct diff_filespec *one = rename_src[j].p->one;
534                         struct diff_score this_src;
535
536                         if (skip_unmodified &&
537                             diff_unmodified_pair(rename_src[j].p))
538                                 continue;
539
540                         this_src.score = estimate_similarity(one, two,
541                                                              minimum_score);
542                         this_src.name_score = basename_same(one, two);
543                         this_src.dst = i;
544                         this_src.src = j;
545                         record_if_better(m, &this_src);
546                         /*
547                          * Once we run estimate_similarity,
548                          * We do not need the text anymore.
549                          */
550                         diff_free_filespec_blob(one);
551                         diff_free_filespec_blob(two);
552                 }
553                 dst_cnt++;
554                 display_progress(progress, (i+1)*rename_src_nr);
555         }
556         stop_progress(&progress);
557
558         /* cost matrix sorted by most to least similar pair */
559         qsort(mx, dst_cnt * NUM_CANDIDATE_PER_DST, sizeof(*mx), score_compare);
560
561         rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
562         if (detect_rename == DIFF_DETECT_COPY)
563                 rename_count += find_renames(mx, dst_cnt, minimum_score, 1);
564         free(mx);
565
566  cleanup:
567         /* At this point, we have found some renames and copies and they
568          * are recorded in rename_dst.  The original list is still in *q.
569          */
570         DIFF_QUEUE_CLEAR(&outq);
571         for (i = 0; i < q->nr; i++) {
572                 struct diff_filepair *p = q->queue[i];
573                 struct diff_filepair *pair_to_free = NULL;
574
575                 if (DIFF_PAIR_UNMERGED(p)) {
576                         diff_q(&outq, p);
577                 }
578                 else if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
579                         /*
580                          * Creation
581                          *
582                          * We would output this create record if it has
583                          * not been turned into a rename/copy already.
584                          */
585                         struct diff_rename_dst *dst =
586                                 locate_rename_dst(p->two, 0);
587                         if (dst && dst->pair) {
588                                 diff_q(&outq, dst->pair);
589                                 pair_to_free = p;
590                         }
591                         else
592                                 /* no matching rename/copy source, so
593                                  * record this as a creation.
594                                  */
595                                 diff_q(&outq, p);
596                 }
597                 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
598                         /*
599                          * Deletion
600                          *
601                          * We would output this delete record if:
602                          *
603                          * (1) this is a broken delete and the counterpart
604                          *     broken create remains in the output; or
605                          * (2) this is not a broken delete, and rename_dst
606                          *     does not have a rename/copy to move p->one->path
607                          *     out of existence.
608                          *
609                          * Otherwise, the counterpart broken create
610                          * has been turned into a rename-edit; or
611                          * delete did not have a matching create to
612                          * begin with.
613                          */
614                         if (DIFF_PAIR_BROKEN(p)) {
615                                 /* broken delete */
616                                 struct diff_rename_dst *dst =
617                                         locate_rename_dst(p->one, 0);
618                                 if (dst && dst->pair)
619                                         /* counterpart is now rename/copy */
620                                         pair_to_free = p;
621                         }
622                         else {
623                                 if (p->one->rename_used)
624                                         /* this path remains */
625                                         pair_to_free = p;
626                         }
627
628                         if (pair_to_free)
629                                 ;
630                         else
631                                 diff_q(&outq, p);
632                 }
633                 else if (!diff_unmodified_pair(p))
634                         /* all the usual ones need to be kept */
635                         diff_q(&outq, p);
636                 else
637                         /* no need to keep unmodified pairs */
638                         pair_to_free = p;
639
640                 if (pair_to_free)
641                         diff_free_filepair(pair_to_free);
642         }
643         diff_debug_queue("done copying original", &outq);
644
645         free(q->queue);
646         *q = outq;
647         diff_debug_queue("done collapsing", q);
648
649         for (i = 0; i < rename_dst_nr; i++)
650                 free_filespec(rename_dst[i].two);
651
652         free(rename_dst);
653         rename_dst = NULL;
654         rename_dst_nr = rename_dst_alloc = 0;
655         free(rename_src);
656         rename_src = NULL;
657         rename_src_nr = rename_src_alloc = 0;
658         return;
659 }