Merge ../gitk
[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 "hash.h"
8
9 /* Table of rename/copy destinations */
10
11 static struct diff_rename_dst {
12         struct diff_filespec *two;
13         struct diff_filepair *pair;
14 } *rename_dst;
15 static int rename_dst_nr, rename_dst_alloc;
16
17 static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
18                                                  int insert_ok)
19 {
20         int first, last;
21
22         first = 0;
23         last = rename_dst_nr;
24         while (last > first) {
25                 int next = (last + first) >> 1;
26                 struct diff_rename_dst *dst = &(rename_dst[next]);
27                 int cmp = strcmp(two->path, dst->two->path);
28                 if (!cmp)
29                         return dst;
30                 if (cmp < 0) {
31                         last = next;
32                         continue;
33                 }
34                 first = next+1;
35         }
36         /* not found */
37         if (!insert_ok)
38                 return NULL;
39         /* insert to make it at "first" */
40         if (rename_dst_alloc <= rename_dst_nr) {
41                 rename_dst_alloc = alloc_nr(rename_dst_alloc);
42                 rename_dst = xrealloc(rename_dst,
43                                       rename_dst_alloc * sizeof(*rename_dst));
44         }
45         rename_dst_nr++;
46         if (first < rename_dst_nr)
47                 memmove(rename_dst + first + 1, rename_dst + first,
48                         (rename_dst_nr - first - 1) * sizeof(*rename_dst));
49         rename_dst[first].two = alloc_filespec(two->path);
50         fill_filespec(rename_dst[first].two, two->sha1, two->mode);
51         rename_dst[first].pair = NULL;
52         return &(rename_dst[first]);
53 }
54
55 /* Table of rename/copy src files */
56 static struct diff_rename_src {
57         struct diff_filespec *one;
58         unsigned short score; /* to remember the break score */
59 } *rename_src;
60 static int rename_src_nr, rename_src_alloc;
61
62 static struct diff_rename_src *register_rename_src(struct diff_filespec *one,
63                                                    unsigned short score)
64 {
65         int first, last;
66
67         first = 0;
68         last = rename_src_nr;
69         while (last > first) {
70                 int next = (last + first) >> 1;
71                 struct diff_rename_src *src = &(rename_src[next]);
72                 int cmp = strcmp(one->path, src->one->path);
73                 if (!cmp)
74                         return src;
75                 if (cmp < 0) {
76                         last = next;
77                         continue;
78                 }
79                 first = next+1;
80         }
81
82         /* insert to make it at "first" */
83         if (rename_src_alloc <= rename_src_nr) {
84                 rename_src_alloc = alloc_nr(rename_src_alloc);
85                 rename_src = xrealloc(rename_src,
86                                       rename_src_alloc * sizeof(*rename_src));
87         }
88         rename_src_nr++;
89         if (first < rename_src_nr)
90                 memmove(rename_src + first + 1, rename_src + first,
91                         (rename_src_nr - first - 1) * sizeof(*rename_src));
92         rename_src[first].one = one;
93         rename_src[first].score = score;
94         return &(rename_src[first]);
95 }
96
97 static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
98 {
99         int src_len = strlen(src->path), dst_len = strlen(dst->path);
100         while (src_len && dst_len) {
101                 char c1 = src->path[--src_len];
102                 char c2 = dst->path[--dst_len];
103                 if (c1 != c2)
104                         return 0;
105                 if (c1 == '/')
106                         return 1;
107         }
108         return (!src_len || src->path[src_len - 1] == '/') &&
109                 (!dst_len || dst->path[dst_len - 1] == '/');
110 }
111
112 struct diff_score {
113         int src; /* index in rename_src */
114         int dst; /* index in rename_dst */
115         int score;
116         int name_score;
117 };
118
119 static int estimate_similarity(struct diff_filespec *src,
120                                struct diff_filespec *dst,
121                                int minimum_score)
122 {
123         /* src points at a file that existed in the original tree (or
124          * optionally a file in the destination tree) and dst points
125          * at a newly created file.  They may be quite similar, in which
126          * case we want to say src is renamed to dst or src is copied into
127          * dst, and then some edit has been applied to dst.
128          *
129          * Compare them and return how similar they are, representing
130          * the score as an integer between 0 and MAX_SCORE.
131          *
132          * When there is an exact match, it is considered a better
133          * match than anything else; the destination does not even
134          * call into this function in that case.
135          */
136         unsigned long max_size, delta_size, base_size, src_copied, literal_added;
137         unsigned long delta_limit;
138         int score;
139
140         /* We deal only with regular files.  Symlink renames are handled
141          * only when they are exact matches --- in other words, no edits
142          * after renaming.
143          */
144         if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
145                 return 0;
146
147         /*
148          * Need to check that source and destination sizes are
149          * filled in before comparing them.
150          *
151          * If we already have "cnt_data" filled in, we know it's
152          * all good (avoid checking the size for zero, as that
153          * is a possible size - we really should have a flag to
154          * say whether the size is valid or not!)
155          */
156         if (!src->cnt_data && diff_populate_filespec(src, 0))
157                 return 0;
158         if (!dst->cnt_data && diff_populate_filespec(dst, 0))
159                 return 0;
160
161         max_size = ((src->size > dst->size) ? src->size : dst->size);
162         base_size = ((src->size < dst->size) ? src->size : dst->size);
163         delta_size = max_size - base_size;
164
165         /* We would not consider edits that change the file size so
166          * drastically.  delta_size must be smaller than
167          * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
168          *
169          * Note that base_size == 0 case is handled here already
170          * and the final score computation below would not have a
171          * divide-by-zero issue.
172          */
173         if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
174                 return 0;
175
176         delta_limit = (unsigned long)
177                 (base_size * (MAX_SCORE-minimum_score) / MAX_SCORE);
178         if (diffcore_count_changes(src, dst,
179                                    &src->cnt_data, &dst->cnt_data,
180                                    delta_limit,
181                                    &src_copied, &literal_added))
182                 return 0;
183
184         /* How similar are they?
185          * what percentage of material in dst are from source?
186          */
187         if (!dst->size)
188                 score = 0; /* should not happen */
189         else
190                 score = (int)(src_copied * MAX_SCORE / max_size);
191         return score;
192 }
193
194 static void record_rename_pair(int dst_index, int src_index, int score)
195 {
196         struct diff_filespec *src, *dst;
197         struct diff_filepair *dp;
198
199         if (rename_dst[dst_index].pair)
200                 die("internal error: dst already matched.");
201
202         src = rename_src[src_index].one;
203         src->rename_used++;
204         src->count++;
205
206         dst = rename_dst[dst_index].two;
207         dst->count++;
208
209         dp = diff_queue(NULL, src, dst);
210         dp->renamed_pair = 1;
211         if (!strcmp(src->path, dst->path))
212                 dp->score = rename_src[src_index].score;
213         else
214                 dp->score = score;
215         rename_dst[dst_index].pair = dp;
216 }
217
218 /*
219  * We sort the rename similarity matrix with the score, in descending
220  * order (the most similar first).
221  */
222 static int score_compare(const void *a_, const void *b_)
223 {
224         const struct diff_score *a = a_, *b = b_;
225
226         if (a->score == b->score)
227                 return b->name_score - a->name_score;
228
229         return b->score - a->score;
230 }
231
232 struct file_similarity {
233         int src_dst, index;
234         struct diff_filespec *filespec;
235         struct file_similarity *next;
236 };
237
238 static int find_identical_files(struct file_similarity *src,
239                                 struct file_similarity *dst)
240 {
241         int renames = 0;
242
243         /*
244          * Walk over all the destinations ...
245          */
246         do {
247                 struct diff_filespec *target = dst->filespec;
248                 struct file_similarity *p, *best;
249                 int i = 100, best_score = -1;
250
251                 /*
252                  * .. to find the best source match
253                  */
254                 best = NULL;
255                 for (p = src; p; p = p->next) {
256                         int score;
257                         struct diff_filespec *source = p->filespec;
258
259                         /* False hash collission? */
260                         if (hashcmp(source->sha1, target->sha1))
261                                 continue;
262                         /* Non-regular files? If so, the modes must match! */
263                         if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
264                                 if (source->mode != target->mode)
265                                         continue;
266                         }
267                         /* Give higher scores to sources that haven't been used already */
268                         score = !source->rename_used;
269                         score += basename_same(source, target);
270                         if (score > best_score) {
271                                 best = p;
272                                 best_score = score;
273                                 if (score == 2)
274                                         break;
275                         }
276
277                         /* Too many identical alternatives? Pick one */
278                         if (!--i)
279                                 break;
280                 }
281                 if (best) {
282                         record_rename_pair(dst->index, best->index, MAX_SCORE);
283                         renames++;
284                 }
285         } while ((dst = dst->next) != NULL);
286         return renames;
287 }
288
289 static void free_similarity_list(struct file_similarity *p)
290 {
291         while (p) {
292                 struct file_similarity *entry = p;
293                 p = p->next;
294                 free(entry);
295         }
296 }
297
298 static int find_same_files(void *ptr)
299 {
300         int ret;
301         struct file_similarity *p = ptr;
302         struct file_similarity *src = NULL, *dst = NULL;
303
304         /* Split the hash list up into sources and destinations */
305         do {
306                 struct file_similarity *entry = p;
307                 p = p->next;
308                 if (entry->src_dst < 0) {
309                         entry->next = src;
310                         src = entry;
311                 } else {
312                         entry->next = dst;
313                         dst = entry;
314                 }
315         } while (p);
316
317         /*
318          * If we have both sources *and* destinations, see if
319          * we can match them up
320          */
321         ret = (src && dst) ? find_identical_files(src, dst) : 0;
322
323         /* Free the hashes and return the number of renames found */
324         free_similarity_list(src);
325         free_similarity_list(dst);
326         return ret;
327 }
328
329 static unsigned int hash_filespec(struct diff_filespec *filespec)
330 {
331         unsigned int hash;
332         if (!filespec->sha1_valid) {
333                 if (diff_populate_filespec(filespec, 0))
334                         return 0;
335                 hash_sha1_file(filespec->data, filespec->size, "blob", filespec->sha1);
336         }
337         memcpy(&hash, filespec->sha1, sizeof(hash));
338         return hash;
339 }
340
341 static void insert_file_table(struct hash_table *table, int src_dst, int index, struct diff_filespec *filespec)
342 {
343         void **pos;
344         unsigned int hash;
345         struct file_similarity *entry = xmalloc(sizeof(*entry));
346
347         entry->src_dst = src_dst;
348         entry->index = index;
349         entry->filespec = filespec;
350         entry->next = NULL;
351
352         hash = hash_filespec(filespec);
353         pos = insert_hash(hash, entry, table);
354
355         /* We already had an entry there? */
356         if (pos) {
357                 entry->next = *pos;
358                 *pos = entry;
359         }
360 }
361
362 /*
363  * Find exact renames first.
364  *
365  * The first round matches up the up-to-date entries,
366  * and then during the second round we try to match
367  * cache-dirty entries as well.
368  */
369 static int find_exact_renames(void)
370 {
371         int i;
372         struct hash_table file_table;
373
374         init_hash(&file_table);
375         for (i = 0; i < rename_src_nr; i++)
376                 insert_file_table(&file_table, -1, i, rename_src[i].one);
377
378         for (i = 0; i < rename_dst_nr; i++)
379                 insert_file_table(&file_table, 1, i, rename_dst[i].two);
380
381         /* Find the renames */
382         i = for_each_hash(&file_table, find_same_files);
383
384         /* .. and free the hash data structure */
385         free_hash(&file_table);
386
387         return i;
388 }
389
390 void diffcore_rename(struct diff_options *options)
391 {
392         int detect_rename = options->detect_rename;
393         int minimum_score = options->rename_score;
394         int rename_limit = options->rename_limit;
395         struct diff_queue_struct *q = &diff_queued_diff;
396         struct diff_queue_struct outq;
397         struct diff_score *mx;
398         int i, j, rename_count;
399         int num_create, num_src, dst_cnt;
400
401         if (!minimum_score)
402                 minimum_score = DEFAULT_RENAME_SCORE;
403
404         for (i = 0; i < q->nr; i++) {
405                 struct diff_filepair *p = q->queue[i];
406                 if (!DIFF_FILE_VALID(p->one)) {
407                         if (!DIFF_FILE_VALID(p->two))
408                                 continue; /* unmerged */
409                         else if (options->single_follow &&
410                                  strcmp(options->single_follow, p->two->path))
411                                 continue; /* not interested */
412                         else
413                                 locate_rename_dst(p->two, 1);
414                 }
415                 else if (!DIFF_FILE_VALID(p->two)) {
416                         /*
417                          * If the source is a broken "delete", and
418                          * they did not really want to get broken,
419                          * that means the source actually stays.
420                          * So we increment the "rename_used" score
421                          * by one, to indicate ourselves as a user
422                          */
423                         if (p->broken_pair && !p->score)
424                                 p->one->rename_used++;
425                         register_rename_src(p->one, p->score);
426                 }
427                 else if (detect_rename == DIFF_DETECT_COPY) {
428                         /*
429                          * Increment the "rename_used" score by
430                          * one, to indicate ourselves as a user.
431                          */
432                         p->one->rename_used++;
433                         register_rename_src(p->one, p->score);
434                 }
435         }
436         if (rename_dst_nr == 0 || rename_src_nr == 0)
437                 goto cleanup; /* nothing to do */
438
439         /*
440          * We really want to cull the candidates list early
441          * with cheap tests in order to avoid doing deltas.
442          */
443         rename_count = find_exact_renames();
444
445         /* Did we only want exact renames? */
446         if (minimum_score == MAX_SCORE)
447                 goto cleanup;
448
449         /*
450          * Calculate how many renames are left (but all the source
451          * files still remain as options for rename/copies!)
452          */
453         num_create = (rename_dst_nr - rename_count);
454         num_src = rename_src_nr;
455
456         /* All done? */
457         if (!num_create)
458                 goto cleanup;
459
460         /*
461          * This basically does a test for the rename matrix not
462          * growing larger than a "rename_limit" square matrix, ie:
463          *
464          *    num_create * num_src > rename_limit * rename_limit
465          *
466          * but handles the potential overflow case specially (and we
467          * assume at least 32-bit integers)
468          */
469         if (rename_limit <= 0 || rename_limit > 32767)
470                 rename_limit = 32767;
471         if (num_create > rename_limit && num_src > rename_limit)
472                 goto cleanup;
473         if (num_create * num_src > rename_limit * rename_limit)
474                 goto cleanup;
475
476         mx = xmalloc(sizeof(*mx) * num_create * num_src);
477         for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
478                 int base = dst_cnt * num_src;
479                 struct diff_filespec *two = rename_dst[i].two;
480                 if (rename_dst[i].pair)
481                         continue; /* dealt with exact match already. */
482                 for (j = 0; j < rename_src_nr; j++) {
483                         struct diff_filespec *one = rename_src[j].one;
484                         struct diff_score *m = &mx[base+j];
485                         m->src = j;
486                         m->dst = i;
487                         m->score = estimate_similarity(one, two,
488                                                        minimum_score);
489                         m->name_score = basename_same(one, two);
490                         diff_free_filespec_blob(one);
491                 }
492                 /* We do not need the text anymore */
493                 diff_free_filespec_blob(two);
494                 dst_cnt++;
495         }
496         /* cost matrix sorted by most to least similar pair */
497         qsort(mx, num_create * num_src, sizeof(*mx), score_compare);
498         for (i = 0; i < num_create * num_src; i++) {
499                 struct diff_rename_dst *dst = &rename_dst[mx[i].dst];
500                 struct diff_filespec *src;
501                 if (dst->pair)
502                         continue; /* already done, either exact or fuzzy. */
503                 if (mx[i].score < minimum_score)
504                         break; /* there is no more usable pair. */
505                 src = rename_src[mx[i].src].one;
506                 if (src->rename_used)
507                         continue;
508                 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
509                 rename_count++;
510         }
511         for (i = 0; i < num_create * num_src; i++) {
512                 struct diff_rename_dst *dst = &rename_dst[mx[i].dst];
513                 if (dst->pair)
514                         continue; /* already done, either exact or fuzzy. */
515                 if (mx[i].score < minimum_score)
516                         break; /* there is no more usable pair. */
517                 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
518                 rename_count++;
519         }
520         free(mx);
521
522  cleanup:
523         /* At this point, we have found some renames and copies and they
524          * are recorded in rename_dst.  The original list is still in *q.
525          */
526         outq.queue = NULL;
527         outq.nr = outq.alloc = 0;
528         for (i = 0; i < q->nr; i++) {
529                 struct diff_filepair *p = q->queue[i];
530                 struct diff_filepair *pair_to_free = NULL;
531
532                 if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
533                         /*
534                          * Creation
535                          *
536                          * We would output this create record if it has
537                          * not been turned into a rename/copy already.
538                          */
539                         struct diff_rename_dst *dst =
540                                 locate_rename_dst(p->two, 0);
541                         if (dst && dst->pair) {
542                                 diff_q(&outq, dst->pair);
543                                 pair_to_free = p;
544                         }
545                         else
546                                 /* no matching rename/copy source, so
547                                  * record this as a creation.
548                                  */
549                                 diff_q(&outq, p);
550                 }
551                 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
552                         /*
553                          * Deletion
554                          *
555                          * We would output this delete record if:
556                          *
557                          * (1) this is a broken delete and the counterpart
558                          *     broken create remains in the output; or
559                          * (2) this is not a broken delete, and rename_dst
560                          *     does not have a rename/copy to move p->one->path
561                          *     out of existence.
562                          *
563                          * Otherwise, the counterpart broken create
564                          * has been turned into a rename-edit; or
565                          * delete did not have a matching create to
566                          * begin with.
567                          */
568                         if (DIFF_PAIR_BROKEN(p)) {
569                                 /* broken delete */
570                                 struct diff_rename_dst *dst =
571                                         locate_rename_dst(p->one, 0);
572                                 if (dst && dst->pair)
573                                         /* counterpart is now rename/copy */
574                                         pair_to_free = p;
575                         }
576                         else {
577                                 if (p->one->rename_used)
578                                         /* this path remains */
579                                         pair_to_free = p;
580                         }
581
582                         if (pair_to_free)
583                                 ;
584                         else
585                                 diff_q(&outq, p);
586                 }
587                 else if (!diff_unmodified_pair(p))
588                         /* all the usual ones need to be kept */
589                         diff_q(&outq, p);
590                 else
591                         /* no need to keep unmodified pairs */
592                         pair_to_free = p;
593
594                 if (pair_to_free)
595                         diff_free_filepair(pair_to_free);
596         }
597         diff_debug_queue("done copying original", &outq);
598
599         free(q->queue);
600         *q = outq;
601         diff_debug_queue("done collapsing", q);
602
603         for (i = 0; i < rename_dst_nr; i++)
604                 free_filespec(rename_dst[i].two);
605
606         free(rename_dst);
607         rename_dst = NULL;
608         rename_dst_nr = rename_dst_alloc = 0;
609         free(rename_src);
610         rename_src = NULL;
611         rename_src_nr = rename_src_alloc = 0;
612         return;
613 }