pkt-line: introduce struct packet_writer
[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 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 sha1hash(filespec->oid.hash);
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
278         struct diff_filespec *target = rename_dst[dst_index].two;
279         struct file_similarity *p, *best = NULL;
280         int i = 100, best_score = -1;
281
282         /*
283          * Find the best source match for specified destination.
284          */
285         p = hashmap_get_from_hash(srcs,
286                                   hash_filespec(options->repo, target),
287                                   NULL);
288         for (; p; p = hashmap_get_next(srcs, p)) {
289                 int score;
290                 struct diff_filespec *source = p->filespec;
291
292                 /* False hash collision? */
293                 if (!oideq(&source->oid, &target->oid))
294                         continue;
295                 /* Non-regular files? If so, the modes must match! */
296                 if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
297                         if (source->mode != target->mode)
298                                 continue;
299                 }
300                 /* Give higher scores to sources that haven't been used already */
301                 score = !source->rename_used;
302                 if (source->rename_used && options->detect_rename != DIFF_DETECT_COPY)
303                         continue;
304                 score += basename_same(source, target);
305                 if (score > best_score) {
306                         best = p;
307                         best_score = score;
308                         if (score == 2)
309                                 break;
310                 }
311
312                 /* Too many identical alternatives? Pick one */
313                 if (!--i)
314                         break;
315         }
316         if (best) {
317                 record_rename_pair(dst_index, best->index, MAX_SCORE);
318                 renames++;
319         }
320         return renames;
321 }
322
323 static void insert_file_table(struct repository *r,
324                               struct hashmap *table, int index,
325                               struct diff_filespec *filespec)
326 {
327         struct file_similarity *entry = xmalloc(sizeof(*entry));
328
329         entry->index = index;
330         entry->filespec = filespec;
331
332         hashmap_entry_init(entry, hash_filespec(r, filespec));
333         hashmap_add(table, entry);
334 }
335
336 /*
337  * Find exact renames first.
338  *
339  * The first round matches up the up-to-date entries,
340  * and then during the second round we try to match
341  * cache-dirty entries as well.
342  */
343 static int find_exact_renames(struct diff_options *options)
344 {
345         int i, renames = 0;
346         struct hashmap file_table;
347
348         /* Add all sources to the hash table in reverse order, because
349          * later on they will be retrieved in LIFO order.
350          */
351         hashmap_init(&file_table, NULL, NULL, rename_src_nr);
352         for (i = rename_src_nr-1; i >= 0; i--)
353                 insert_file_table(options->repo,
354                                   &file_table, i,
355                                   rename_src[i].p->one);
356
357         /* Walk the destinations and find best source match */
358         for (i = 0; i < rename_dst_nr; i++)
359                 renames += find_identical_files(&file_table, i, options);
360
361         /* Free the hash data structure and entries */
362         hashmap_free(&file_table, 1);
363
364         return renames;
365 }
366
367 #define NUM_CANDIDATE_PER_DST 4
368 static void record_if_better(struct diff_score m[], struct diff_score *o)
369 {
370         int i, worst;
371
372         /* find the worst one */
373         worst = 0;
374         for (i = 1; i < NUM_CANDIDATE_PER_DST; i++)
375                 if (score_compare(&m[i], &m[worst]) > 0)
376                         worst = i;
377
378         /* is it better than the worst one? */
379         if (score_compare(&m[worst], o) > 0)
380                 m[worst] = *o;
381 }
382
383 /*
384  * Returns:
385  * 0 if we are under the limit;
386  * 1 if we need to disable inexact rename detection;
387  * 2 if we would be under the limit if we were given -C instead of -C -C.
388  */
389 static int too_many_rename_candidates(int num_create,
390                                       struct diff_options *options)
391 {
392         int rename_limit = options->rename_limit;
393         int num_src = rename_src_nr;
394         int i;
395
396         options->needed_rename_limit = 0;
397
398         /*
399          * This basically does a test for the rename matrix not
400          * growing larger than a "rename_limit" square matrix, ie:
401          *
402          *    num_create * num_src > rename_limit * rename_limit
403          */
404         if (rename_limit <= 0)
405                 rename_limit = 32767;
406         if ((num_create <= rename_limit || num_src <= rename_limit) &&
407             ((uint64_t)num_create * (uint64_t)num_src
408              <= (uint64_t)rename_limit * (uint64_t)rename_limit))
409                 return 0;
410
411         options->needed_rename_limit =
412                 num_src > num_create ? num_src : num_create;
413
414         /* Are we running under -C -C? */
415         if (!options->flags.find_copies_harder)
416                 return 1;
417
418         /* Would we bust the limit if we were running under -C? */
419         for (num_src = i = 0; i < rename_src_nr; i++) {
420                 if (diff_unmodified_pair(rename_src[i].p))
421                         continue;
422                 num_src++;
423         }
424         if ((num_create <= rename_limit || num_src <= rename_limit) &&
425             ((uint64_t)num_create * (uint64_t)num_src
426              <= (uint64_t)rename_limit * (uint64_t)rename_limit))
427                 return 2;
428         return 1;
429 }
430
431 static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, int copies)
432 {
433         int count = 0, i;
434
435         for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
436                 struct diff_rename_dst *dst;
437
438                 if ((mx[i].dst < 0) ||
439                     (mx[i].score < minimum_score))
440                         break; /* there is no more usable pair. */
441                 dst = &rename_dst[mx[i].dst];
442                 if (dst->pair)
443                         continue; /* already done, either exact or fuzzy. */
444                 if (!copies && rename_src[mx[i].src].p->one->rename_used)
445                         continue;
446                 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
447                 count++;
448         }
449         return count;
450 }
451
452 void diffcore_rename(struct diff_options *options)
453 {
454         int detect_rename = options->detect_rename;
455         int minimum_score = options->rename_score;
456         struct diff_queue_struct *q = &diff_queued_diff;
457         struct diff_queue_struct outq;
458         struct diff_score *mx;
459         int i, j, rename_count, skip_unmodified = 0;
460         int num_create, dst_cnt;
461         struct progress *progress = NULL;
462
463         if (!minimum_score)
464                 minimum_score = DEFAULT_RENAME_SCORE;
465
466         for (i = 0; i < q->nr; i++) {
467                 struct diff_filepair *p = q->queue[i];
468                 if (!DIFF_FILE_VALID(p->one)) {
469                         if (!DIFF_FILE_VALID(p->two))
470                                 continue; /* unmerged */
471                         else if (options->single_follow &&
472                                  strcmp(options->single_follow, p->two->path))
473                                 continue; /* not interested */
474                         else if (!options->flags.rename_empty &&
475                                  is_empty_blob_oid(&p->two->oid))
476                                 continue;
477                         else if (add_rename_dst(p->two) < 0) {
478                                 warning("skipping rename detection, detected"
479                                         " duplicate destination '%s'",
480                                         p->two->path);
481                                 goto cleanup;
482                         }
483                 }
484                 else if (!options->flags.rename_empty &&
485                          is_empty_blob_oid(&p->one->oid))
486                         continue;
487                 else if (!DIFF_PAIR_UNMERGED(p) && !DIFF_FILE_VALID(p->two)) {
488                         /*
489                          * If the source is a broken "delete", and
490                          * they did not really want to get broken,
491                          * that means the source actually stays.
492                          * So we increment the "rename_used" score
493                          * by one, to indicate ourselves as a user
494                          */
495                         if (p->broken_pair && !p->score)
496                                 p->one->rename_used++;
497                         register_rename_src(p);
498                 }
499                 else if (detect_rename == DIFF_DETECT_COPY) {
500                         /*
501                          * Increment the "rename_used" score by
502                          * one, to indicate ourselves as a user.
503                          */
504                         p->one->rename_used++;
505                         register_rename_src(p);
506                 }
507         }
508         if (rename_dst_nr == 0 || rename_src_nr == 0)
509                 goto cleanup; /* nothing to do */
510
511         /*
512          * We really want to cull the candidates list early
513          * with cheap tests in order to avoid doing deltas.
514          */
515         rename_count = find_exact_renames(options);
516
517         /* Did we only want exact renames? */
518         if (minimum_score == MAX_SCORE)
519                 goto cleanup;
520
521         /*
522          * Calculate how many renames are left (but all the source
523          * files still remain as options for rename/copies!)
524          */
525         num_create = (rename_dst_nr - rename_count);
526
527         /* All done? */
528         if (!num_create)
529                 goto cleanup;
530
531         switch (too_many_rename_candidates(num_create, options)) {
532         case 1:
533                 goto cleanup;
534         case 2:
535                 options->degraded_cc_to_c = 1;
536                 skip_unmodified = 1;
537                 break;
538         default:
539                 break;
540         }
541
542         if (options->show_rename_progress) {
543                 progress = start_delayed_progress(
544                                 _("Performing inexact rename detection"),
545                                 (uint64_t)rename_dst_nr * (uint64_t)rename_src_nr);
546         }
547
548         mx = xcalloc(st_mult(NUM_CANDIDATE_PER_DST, num_create), sizeof(*mx));
549         for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
550                 struct diff_filespec *two = rename_dst[i].two;
551                 struct diff_score *m;
552
553                 if (rename_dst[i].pair)
554                         continue; /* dealt with exact match already. */
555
556                 m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST];
557                 for (j = 0; j < NUM_CANDIDATE_PER_DST; j++)
558                         m[j].dst = -1;
559
560                 for (j = 0; j < rename_src_nr; j++) {
561                         struct diff_filespec *one = rename_src[j].p->one;
562                         struct diff_score this_src;
563
564                         if (skip_unmodified &&
565                             diff_unmodified_pair(rename_src[j].p))
566                                 continue;
567
568                         this_src.score = estimate_similarity(options->repo,
569                                                              one, two,
570                                                              minimum_score);
571                         this_src.name_score = basename_same(one, two);
572                         this_src.dst = i;
573                         this_src.src = j;
574                         record_if_better(m, &this_src);
575                         /*
576                          * Once we run estimate_similarity,
577                          * We do not need the text anymore.
578                          */
579                         diff_free_filespec_blob(one);
580                         diff_free_filespec_blob(two);
581                 }
582                 dst_cnt++;
583                 display_progress(progress, (uint64_t)(i+1)*(uint64_t)rename_src_nr);
584         }
585         stop_progress(&progress);
586
587         /* cost matrix sorted by most to least similar pair */
588         QSORT(mx, dst_cnt * NUM_CANDIDATE_PER_DST, score_compare);
589
590         rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
591         if (detect_rename == DIFF_DETECT_COPY)
592                 rename_count += find_renames(mx, dst_cnt, minimum_score, 1);
593         free(mx);
594
595  cleanup:
596         /* At this point, we have found some renames and copies and they
597          * are recorded in rename_dst.  The original list is still in *q.
598          */
599         DIFF_QUEUE_CLEAR(&outq);
600         for (i = 0; i < q->nr; i++) {
601                 struct diff_filepair *p = q->queue[i];
602                 struct diff_filepair *pair_to_free = NULL;
603
604                 if (DIFF_PAIR_UNMERGED(p)) {
605                         diff_q(&outq, p);
606                 }
607                 else if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
608                         /*
609                          * Creation
610                          *
611                          * We would output this create record if it has
612                          * not been turned into a rename/copy already.
613                          */
614                         struct diff_rename_dst *dst = locate_rename_dst(p->two);
615                         if (dst && dst->pair) {
616                                 diff_q(&outq, dst->pair);
617                                 pair_to_free = p;
618                         }
619                         else
620                                 /* no matching rename/copy source, so
621                                  * record this as a creation.
622                                  */
623                                 diff_q(&outq, p);
624                 }
625                 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
626                         /*
627                          * Deletion
628                          *
629                          * We would output this delete record if:
630                          *
631                          * (1) this is a broken delete and the counterpart
632                          *     broken create remains in the output; or
633                          * (2) this is not a broken delete, and rename_dst
634                          *     does not have a rename/copy to move p->one->path
635                          *     out of existence.
636                          *
637                          * Otherwise, the counterpart broken create
638                          * has been turned into a rename-edit; or
639                          * delete did not have a matching create to
640                          * begin with.
641                          */
642                         if (DIFF_PAIR_BROKEN(p)) {
643                                 /* broken delete */
644                                 struct diff_rename_dst *dst = locate_rename_dst(p->one);
645                                 if (dst && dst->pair)
646                                         /* counterpart is now rename/copy */
647                                         pair_to_free = p;
648                         }
649                         else {
650                                 if (p->one->rename_used)
651                                         /* this path remains */
652                                         pair_to_free = p;
653                         }
654
655                         if (pair_to_free)
656                                 ;
657                         else
658                                 diff_q(&outq, p);
659                 }
660                 else if (!diff_unmodified_pair(p))
661                         /* all the usual ones need to be kept */
662                         diff_q(&outq, p);
663                 else
664                         /* no need to keep unmodified pairs */
665                         pair_to_free = p;
666
667                 if (pair_to_free)
668                         diff_free_filepair(pair_to_free);
669         }
670         diff_debug_queue("done copying original", &outq);
671
672         free(q->queue);
673         *q = outq;
674         diff_debug_queue("done collapsing", q);
675
676         for (i = 0; i < rename_dst_nr; i++)
677                 free_filespec(rename_dst[i].two);
678
679         FREE_AND_NULL(rename_dst);
680         rename_dst_nr = rename_dst_alloc = 0;
681         FREE_AND_NULL(rename_src);
682         rename_src_nr = rename_src_alloc = 0;
683         return;
684 }