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[git.git] / diffcore-rename.c
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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"
10 /* Table of rename/copy destinations */
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;
18 static int find_rename_dst(struct diff_filespec *two)
20 int first, last;
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 next;
30 if (cmp < 0) {
31 last = next;
32 continue;
34 first = next+1;
36 return -first - 1;
39 static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two)
41 int ofs = find_rename_dst(two);
42 return ofs < 0 ? NULL : &rename_dst[ofs];
46 * Returns 0 on success, -1 if we found a duplicate.
48 static int add_rename_dst(struct diff_filespec *two)
50 int first = find_rename_dst(two);
52 if (first >= 0)
53 return -1;
54 first = -first - 1;
56 /* insert to make it at "first" */
57 ALLOC_GROW(rename_dst, rename_dst_nr + 1, rename_dst_alloc);
58 rename_dst_nr++;
59 if (first < rename_dst_nr)
60 MOVE_ARRAY(rename_dst + first + 1, rename_dst + first,
61 rename_dst_nr - first - 1);
62 rename_dst[first].two = alloc_filespec(two->path);
63 fill_filespec(rename_dst[first].two, &two->oid, two->oid_valid,
64 two->mode);
65 rename_dst[first].pair = NULL;
66 return 0;
69 /* Table of rename/copy src files */
70 static struct diff_rename_src {
71 struct diff_filepair *p;
72 unsigned short score; /* to remember the break score */
73 } *rename_src;
74 static int rename_src_nr, rename_src_alloc;
76 static struct diff_rename_src *register_rename_src(struct diff_filepair *p)
78 int first, last;
79 struct diff_filespec *one = p->one;
80 unsigned short score = p->score;
82 first = 0;
83 last = rename_src_nr;
84 while (last > first) {
85 int next = (last + first) >> 1;
86 struct diff_rename_src *src = &(rename_src[next]);
87 int cmp = strcmp(one->path, src->p->one->path);
88 if (!cmp)
89 return src;
90 if (cmp < 0) {
91 last = next;
92 continue;
94 first = next+1;
97 /* insert to make it at "first" */
98 ALLOC_GROW(rename_src, rename_src_nr + 1, rename_src_alloc);
99 rename_src_nr++;
100 if (first < rename_src_nr)
101 MOVE_ARRAY(rename_src + first + 1, rename_src + first,
102 rename_src_nr - first - 1);
103 rename_src[first].p = p;
104 rename_src[first].score = score;
105 return &(rename_src[first]);
108 static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
110 int src_len = strlen(src->path), dst_len = strlen(dst->path);
111 while (src_len && dst_len) {
112 char c1 = src->path[--src_len];
113 char c2 = dst->path[--dst_len];
114 if (c1 != c2)
115 return 0;
116 if (c1 == '/')
117 return 1;
119 return (!src_len || src->path[src_len - 1] == '/') &&
120 (!dst_len || dst->path[dst_len - 1] == '/');
123 struct diff_score {
124 int src; /* index in rename_src */
125 int dst; /* index in rename_dst */
126 unsigned short score;
127 short name_score;
130 static int estimate_similarity(struct diff_filespec *src,
131 struct diff_filespec *dst,
132 int minimum_score)
134 /* src points at a file that existed in the original tree (or
135 * optionally a file in the destination tree) and dst points
136 * at a newly created file. They may be quite similar, in which
137 * case we want to say src is renamed to dst or src is copied into
138 * dst, and then some edit has been applied to dst.
140 * Compare them and return how similar they are, representing
141 * the score as an integer between 0 and MAX_SCORE.
143 * When there is an exact match, it is considered a better
144 * match than anything else; the destination does not even
145 * call into this function in that case.
147 unsigned long max_size, delta_size, base_size, src_copied, literal_added;
148 int score;
150 /* We deal only with regular files. Symlink renames are handled
151 * only when they are exact matches --- in other words, no edits
152 * after renaming.
154 if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
155 return 0;
158 * Need to check that source and destination sizes are
159 * filled in before comparing them.
161 * If we already have "cnt_data" filled in, we know it's
162 * all good (avoid checking the size for zero, as that
163 * is a possible size - we really should have a flag to
164 * say whether the size is valid or not!)
166 if (!src->cnt_data &&
167 diff_populate_filespec(src, CHECK_SIZE_ONLY))
168 return 0;
169 if (!dst->cnt_data &&
170 diff_populate_filespec(dst, CHECK_SIZE_ONLY))
171 return 0;
173 max_size = ((src->size > dst->size) ? src->size : dst->size);
174 base_size = ((src->size < dst->size) ? src->size : dst->size);
175 delta_size = max_size - base_size;
177 /* We would not consider edits that change the file size so
178 * drastically. delta_size must be smaller than
179 * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
181 * Note that base_size == 0 case is handled here already
182 * and the final score computation below would not have a
183 * divide-by-zero issue.
185 if (max_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
186 return 0;
188 if (!src->cnt_data && diff_populate_filespec(src, 0))
189 return 0;
190 if (!dst->cnt_data && diff_populate_filespec(dst, 0))
191 return 0;
193 if (diffcore_count_changes(src, dst,
194 &src->cnt_data, &dst->cnt_data,
195 &src_copied, &literal_added))
196 return 0;
198 /* How similar are they?
199 * what percentage of material in dst are from source?
201 if (!dst->size)
202 score = 0; /* should not happen */
203 else
204 score = (int)(src_copied * MAX_SCORE / max_size);
205 return score;
208 static void record_rename_pair(int dst_index, int src_index, int score)
210 struct diff_filespec *src, *dst;
211 struct diff_filepair *dp;
213 if (rename_dst[dst_index].pair)
214 die("internal error: dst already matched.");
216 src = rename_src[src_index].p->one;
217 src->rename_used++;
218 src->count++;
220 dst = rename_dst[dst_index].two;
221 dst->count++;
223 dp = diff_queue(NULL, src, dst);
224 dp->renamed_pair = 1;
225 if (!strcmp(src->path, dst->path))
226 dp->score = rename_src[src_index].score;
227 else
228 dp->score = score;
229 rename_dst[dst_index].pair = dp;
233 * We sort the rename similarity matrix with the score, in descending
234 * order (the most similar first).
236 static int score_compare(const void *a_, const void *b_)
238 const struct diff_score *a = a_, *b = b_;
240 /* sink the unused ones to the bottom */
241 if (a->dst < 0)
242 return (0 <= b->dst);
243 else if (b->dst < 0)
244 return -1;
246 if (a->score == b->score)
247 return b->name_score - a->name_score;
249 return b->score - a->score;
252 struct file_similarity {
253 struct hashmap_entry entry;
254 int index;
255 struct diff_filespec *filespec;
258 static unsigned int hash_filespec(struct diff_filespec *filespec)
260 if (!filespec->oid_valid) {
261 if (diff_populate_filespec(filespec, 0))
262 return 0;
263 hash_object_file(filespec->data, filespec->size, "blob",
264 &filespec->oid);
266 return sha1hash(filespec->oid.hash);
269 static int find_identical_files(struct hashmap *srcs,
270 int dst_index,
271 struct diff_options *options)
273 int renames = 0;
275 struct diff_filespec *target = rename_dst[dst_index].two;
276 struct file_similarity *p, *best = NULL;
277 int i = 100, best_score = -1;
280 * Find the best source match for specified destination.
282 p = hashmap_get_from_hash(srcs, hash_filespec(target), NULL);
283 for (; p; p = hashmap_get_next(srcs, p)) {
284 int score;
285 struct diff_filespec *source = p->filespec;
287 /* False hash collision? */
288 if (oidcmp(&source->oid, &target->oid))
289 continue;
290 /* Non-regular files? If so, the modes must match! */
291 if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
292 if (source->mode != target->mode)
293 continue;
295 /* Give higher scores to sources that haven't been used already */
296 score = !source->rename_used;
297 if (source->rename_used && options->detect_rename != DIFF_DETECT_COPY)
298 continue;
299 score += basename_same(source, target);
300 if (score > best_score) {
301 best = p;
302 best_score = score;
303 if (score == 2)
304 break;
307 /* Too many identical alternatives? Pick one */
308 if (!--i)
309 break;
311 if (best) {
312 record_rename_pair(dst_index, best->index, MAX_SCORE);
313 renames++;
315 return renames;
318 static void insert_file_table(struct hashmap *table, int index, struct diff_filespec *filespec)
320 struct file_similarity *entry = xmalloc(sizeof(*entry));
322 entry->index = index;
323 entry->filespec = filespec;
325 hashmap_entry_init(entry, hash_filespec(filespec));
326 hashmap_add(table, entry);
330 * Find exact renames first.
332 * The first round matches up the up-to-date entries,
333 * and then during the second round we try to match
334 * cache-dirty entries as well.
336 static int find_exact_renames(struct diff_options *options)
338 int i, renames = 0;
339 struct hashmap file_table;
341 /* Add all sources to the hash table in reverse order, because
342 * later on they will be retrieved in LIFO order.
344 hashmap_init(&file_table, NULL, NULL, rename_src_nr);
345 for (i = rename_src_nr-1; i >= 0; i--)
346 insert_file_table(&file_table, i, rename_src[i].p->one);
348 /* Walk the destinations and find best source match */
349 for (i = 0; i < rename_dst_nr; i++)
350 renames += find_identical_files(&file_table, i, options);
352 /* Free the hash data structure and entries */
353 hashmap_free(&file_table, 1);
355 return renames;
358 #define NUM_CANDIDATE_PER_DST 4
359 static void record_if_better(struct diff_score m[], struct diff_score *o)
361 int i, worst;
363 /* find the worst one */
364 worst = 0;
365 for (i = 1; i < NUM_CANDIDATE_PER_DST; i++)
366 if (score_compare(&m[i], &m[worst]) > 0)
367 worst = i;
369 /* is it better than the worst one? */
370 if (score_compare(&m[worst], o) > 0)
371 m[worst] = *o;
375 * Returns:
376 * 0 if we are under the limit;
377 * 1 if we need to disable inexact rename detection;
378 * 2 if we would be under the limit if we were given -C instead of -C -C.
380 static int too_many_rename_candidates(int num_create,
381 struct diff_options *options)
383 int rename_limit = options->rename_limit;
384 int num_src = rename_src_nr;
385 int i;
387 options->needed_rename_limit = 0;
390 * This basically does a test for the rename matrix not
391 * growing larger than a "rename_limit" square matrix, ie:
393 * num_create * num_src > rename_limit * rename_limit
395 if (rename_limit <= 0)
396 rename_limit = 32767;
397 if ((num_create <= rename_limit || num_src <= rename_limit) &&
398 ((uint64_t)num_create * (uint64_t)num_src
399 <= (uint64_t)rename_limit * (uint64_t)rename_limit))
400 return 0;
402 options->needed_rename_limit =
403 num_src > num_create ? num_src : num_create;
405 /* Are we running under -C -C? */
406 if (!options->flags.find_copies_harder)
407 return 1;
409 /* Would we bust the limit if we were running under -C? */
410 for (num_src = i = 0; i < rename_src_nr; i++) {
411 if (diff_unmodified_pair(rename_src[i].p))
412 continue;
413 num_src++;
415 if ((num_create <= rename_limit || num_src <= rename_limit) &&
416 ((uint64_t)num_create * (uint64_t)num_src
417 <= (uint64_t)rename_limit * (uint64_t)rename_limit))
418 return 2;
419 return 1;
422 static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, int copies)
424 int count = 0, i;
426 for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
427 struct diff_rename_dst *dst;
429 if ((mx[i].dst < 0) ||
430 (mx[i].score < minimum_score))
431 break; /* there is no more usable pair. */
432 dst = &rename_dst[mx[i].dst];
433 if (dst->pair)
434 continue; /* already done, either exact or fuzzy. */
435 if (!copies && rename_src[mx[i].src].p->one->rename_used)
436 continue;
437 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
438 count++;
440 return count;
443 void diffcore_rename(struct diff_options *options)
445 int detect_rename = options->detect_rename;
446 int minimum_score = options->rename_score;
447 struct diff_queue_struct *q = &diff_queued_diff;
448 struct diff_queue_struct outq;
449 struct diff_score *mx;
450 int i, j, rename_count, skip_unmodified = 0;
451 int num_create, dst_cnt;
452 struct progress *progress = NULL;
454 if (!minimum_score)
455 minimum_score = DEFAULT_RENAME_SCORE;
457 for (i = 0; i < q->nr; i++) {
458 struct diff_filepair *p = q->queue[i];
459 if (!DIFF_FILE_VALID(p->one)) {
460 if (!DIFF_FILE_VALID(p->two))
461 continue; /* unmerged */
462 else if (options->single_follow &&
463 strcmp(options->single_follow, p->two->path))
464 continue; /* not interested */
465 else if (!options->flags.rename_empty &&
466 is_empty_blob_oid(&p->two->oid))
467 continue;
468 else if (add_rename_dst(p->two) < 0) {
469 warning("skipping rename detection, detected"
470 " duplicate destination '%s'",
471 p->two->path);
472 goto cleanup;
475 else if (!options->flags.rename_empty &&
476 is_empty_blob_oid(&p->one->oid))
477 continue;
478 else if (!DIFF_PAIR_UNMERGED(p) && !DIFF_FILE_VALID(p->two)) {
480 * If the source is a broken "delete", and
481 * they did not really want to get broken,
482 * that means the source actually stays.
483 * So we increment the "rename_used" score
484 * by one, to indicate ourselves as a user
486 if (p->broken_pair && !p->score)
487 p->one->rename_used++;
488 register_rename_src(p);
490 else if (detect_rename == DIFF_DETECT_COPY) {
492 * Increment the "rename_used" score by
493 * one, to indicate ourselves as a user.
495 p->one->rename_used++;
496 register_rename_src(p);
499 if (rename_dst_nr == 0 || rename_src_nr == 0)
500 goto cleanup; /* nothing to do */
503 * We really want to cull the candidates list early
504 * with cheap tests in order to avoid doing deltas.
506 rename_count = find_exact_renames(options);
508 /* Did we only want exact renames? */
509 if (minimum_score == MAX_SCORE)
510 goto cleanup;
513 * Calculate how many renames are left (but all the source
514 * files still remain as options for rename/copies!)
516 num_create = (rename_dst_nr - rename_count);
518 /* All done? */
519 if (!num_create)
520 goto cleanup;
522 switch (too_many_rename_candidates(num_create, options)) {
523 case 1:
524 goto cleanup;
525 case 2:
526 options->degraded_cc_to_c = 1;
527 skip_unmodified = 1;
528 break;
529 default:
530 break;
533 if (options->show_rename_progress) {
534 progress = start_delayed_progress(
535 _("Performing inexact rename detection"),
536 (uint64_t)rename_dst_nr * (uint64_t)rename_src_nr);
539 mx = xcalloc(st_mult(NUM_CANDIDATE_PER_DST, num_create), sizeof(*mx));
540 for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
541 struct diff_filespec *two = rename_dst[i].two;
542 struct diff_score *m;
544 if (rename_dst[i].pair)
545 continue; /* dealt with exact match already. */
547 m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST];
548 for (j = 0; j < NUM_CANDIDATE_PER_DST; j++)
549 m[j].dst = -1;
551 for (j = 0; j < rename_src_nr; j++) {
552 struct diff_filespec *one = rename_src[j].p->one;
553 struct diff_score this_src;
555 if (skip_unmodified &&
556 diff_unmodified_pair(rename_src[j].p))
557 continue;
559 this_src.score = estimate_similarity(one, two,
560 minimum_score);
561 this_src.name_score = basename_same(one, two);
562 this_src.dst = i;
563 this_src.src = j;
564 record_if_better(m, &this_src);
566 * Once we run estimate_similarity,
567 * We do not need the text anymore.
569 diff_free_filespec_blob(one);
570 diff_free_filespec_blob(two);
572 dst_cnt++;
573 display_progress(progress, (uint64_t)(i+1)*(uint64_t)rename_src_nr);
575 stop_progress(&progress);
577 /* cost matrix sorted by most to least similar pair */
578 QSORT(mx, dst_cnt * NUM_CANDIDATE_PER_DST, score_compare);
580 rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
581 if (detect_rename == DIFF_DETECT_COPY)
582 rename_count += find_renames(mx, dst_cnt, minimum_score, 1);
583 free(mx);
585 cleanup:
586 /* At this point, we have found some renames and copies and they
587 * are recorded in rename_dst. The original list is still in *q.
589 DIFF_QUEUE_CLEAR(&outq);
590 for (i = 0; i < q->nr; i++) {
591 struct diff_filepair *p = q->queue[i];
592 struct diff_filepair *pair_to_free = NULL;
594 if (DIFF_PAIR_UNMERGED(p)) {
595 diff_q(&outq, p);
597 else if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
599 * Creation
601 * We would output this create record if it has
602 * not been turned into a rename/copy already.
604 struct diff_rename_dst *dst = locate_rename_dst(p->two);
605 if (dst && dst->pair) {
606 diff_q(&outq, dst->pair);
607 pair_to_free = p;
609 else
610 /* no matching rename/copy source, so
611 * record this as a creation.
613 diff_q(&outq, p);
615 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
617 * Deletion
619 * We would output this delete record if:
621 * (1) this is a broken delete and the counterpart
622 * broken create remains in the output; or
623 * (2) this is not a broken delete, and rename_dst
624 * does not have a rename/copy to move p->one->path
625 * out of existence.
627 * Otherwise, the counterpart broken create
628 * has been turned into a rename-edit; or
629 * delete did not have a matching create to
630 * begin with.
632 if (DIFF_PAIR_BROKEN(p)) {
633 /* broken delete */
634 struct diff_rename_dst *dst = locate_rename_dst(p->one);
635 if (dst && dst->pair)
636 /* counterpart is now rename/copy */
637 pair_to_free = p;
639 else {
640 if (p->one->rename_used)
641 /* this path remains */
642 pair_to_free = p;
645 if (pair_to_free)
647 else
648 diff_q(&outq, p);
650 else if (!diff_unmodified_pair(p))
651 /* all the usual ones need to be kept */
652 diff_q(&outq, p);
653 else
654 /* no need to keep unmodified pairs */
655 pair_to_free = p;
657 if (pair_to_free)
658 diff_free_filepair(pair_to_free);
660 diff_debug_queue("done copying original", &outq);
662 free(q->queue);
663 *q = outq;
664 diff_debug_queue("done collapsing", q);
666 for (i = 0; i < rename_dst_nr; i++)
667 free_filespec(rename_dst[i].two);
669 FREE_AND_NULL(rename_dst);
670 rename_dst_nr = rename_dst_alloc = 0;
671 FREE_AND_NULL(rename_src);
672 rename_src_nr = rename_src_alloc = 0;
673 return;