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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 memmove(rename_dst + first + 1, rename_dst + first,
61 (rename_dst_nr - first - 1) * sizeof(*rename_dst));
62 rename_dst[first].two = alloc_filespec(two->path);
63 fill_filespec(rename_dst[first].two, two->sha1, two->sha1_valid, two->mode);
64 rename_dst[first].pair = NULL;
65 return 0;
68 /* Table of rename/copy src files */
69 static struct diff_rename_src {
70 struct diff_filepair *p;
71 unsigned short score; /* to remember the break score */
72 } *rename_src;
73 static int rename_src_nr, rename_src_alloc;
75 static struct diff_rename_src *register_rename_src(struct diff_filepair *p)
77 int first, last;
78 struct diff_filespec *one = p->one;
79 unsigned short score = p->score;
81 first = 0;
82 last = rename_src_nr;
83 while (last > first) {
84 int next = (last + first) >> 1;
85 struct diff_rename_src *src = &(rename_src[next]);
86 int cmp = strcmp(one->path, src->p->one->path);
87 if (!cmp)
88 return src;
89 if (cmp < 0) {
90 last = next;
91 continue;
93 first = next+1;
96 /* insert to make it at "first" */
97 ALLOC_GROW(rename_src, rename_src_nr + 1, rename_src_alloc);
98 rename_src_nr++;
99 if (first < rename_src_nr)
100 memmove(rename_src + first + 1, rename_src + first,
101 (rename_src_nr - first - 1) * sizeof(*rename_src));
102 rename_src[first].p = p;
103 rename_src[first].score = score;
104 return &(rename_src[first]);
107 static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
109 int src_len = strlen(src->path), dst_len = strlen(dst->path);
110 while (src_len && dst_len) {
111 char c1 = src->path[--src_len];
112 char c2 = dst->path[--dst_len];
113 if (c1 != c2)
114 return 0;
115 if (c1 == '/')
116 return 1;
118 return (!src_len || src->path[src_len - 1] == '/') &&
119 (!dst_len || dst->path[dst_len - 1] == '/');
122 struct diff_score {
123 int src; /* index in rename_src */
124 int dst; /* index in rename_dst */
125 unsigned short score;
126 short name_score;
129 static int estimate_similarity(struct diff_filespec *src,
130 struct diff_filespec *dst,
131 int minimum_score)
133 /* src points at a file that existed in the original tree (or
134 * optionally a file in the destination tree) and dst points
135 * at a newly created file. They may be quite similar, in which
136 * case we want to say src is renamed to dst or src is copied into
137 * dst, and then some edit has been applied to dst.
139 * Compare them and return how similar they are, representing
140 * the score as an integer between 0 and MAX_SCORE.
142 * When there is an exact match, it is considered a better
143 * match than anything else; the destination does not even
144 * call into this function in that case.
146 unsigned long max_size, delta_size, base_size, src_copied, literal_added;
147 unsigned long delta_limit;
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 delta_limit = (unsigned long)
194 (base_size * (MAX_SCORE-minimum_score) / MAX_SCORE);
195 if (diffcore_count_changes(src, dst,
196 &src->cnt_data, &dst->cnt_data,
197 delta_limit,
198 &src_copied, &literal_added))
199 return 0;
201 /* How similar are they?
202 * what percentage of material in dst are from source?
204 if (!dst->size)
205 score = 0; /* should not happen */
206 else
207 score = (int)(src_copied * MAX_SCORE / max_size);
208 return score;
211 static void record_rename_pair(int dst_index, int src_index, int score)
213 struct diff_filespec *src, *dst;
214 struct diff_filepair *dp;
216 if (rename_dst[dst_index].pair)
217 die("internal error: dst already matched.");
219 src = rename_src[src_index].p->one;
220 src->rename_used++;
221 src->count++;
223 dst = rename_dst[dst_index].two;
224 dst->count++;
226 dp = diff_queue(NULL, src, dst);
227 dp->renamed_pair = 1;
228 if (!strcmp(src->path, dst->path))
229 dp->score = rename_src[src_index].score;
230 else
231 dp->score = score;
232 rename_dst[dst_index].pair = dp;
236 * We sort the rename similarity matrix with the score, in descending
237 * order (the most similar first).
239 static int score_compare(const void *a_, const void *b_)
241 const struct diff_score *a = a_, *b = b_;
243 /* sink the unused ones to the bottom */
244 if (a->dst < 0)
245 return (0 <= b->dst);
246 else if (b->dst < 0)
247 return -1;
249 if (a->score == b->score)
250 return b->name_score - a->name_score;
252 return b->score - a->score;
255 struct file_similarity {
256 struct hashmap_entry entry;
257 int index;
258 struct diff_filespec *filespec;
261 static unsigned int hash_filespec(struct diff_filespec *filespec)
263 if (!filespec->sha1_valid) {
264 if (diff_populate_filespec(filespec, 0))
265 return 0;
266 hash_sha1_file(filespec->data, filespec->size, "blob", filespec->sha1);
268 return sha1hash(filespec->sha1);
271 static int find_identical_files(struct hashmap *srcs,
272 int dst_index,
273 struct diff_options *options)
275 int renames = 0;
277 struct diff_filespec *target = rename_dst[dst_index].two;
278 struct file_similarity *p, *best = NULL;
279 int i = 100, best_score = -1;
282 * Find the best source match for specified destination.
284 p = hashmap_get_from_hash(srcs, hash_filespec(target), NULL);
285 for (; p; p = hashmap_get_next(srcs, p)) {
286 int score;
287 struct diff_filespec *source = p->filespec;
289 /* False hash collision? */
290 if (hashcmp(source->sha1, target->sha1))
291 continue;
292 /* Non-regular files? If so, the modes must match! */
293 if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
294 if (source->mode != target->mode)
295 continue;
297 /* Give higher scores to sources that haven't been used already */
298 score = !source->rename_used;
299 if (source->rename_used && options->detect_rename != DIFF_DETECT_COPY)
300 continue;
301 score += basename_same(source, target);
302 if (score > best_score) {
303 best = p;
304 best_score = score;
305 if (score == 2)
306 break;
309 /* Too many identical alternatives? Pick one */
310 if (!--i)
311 break;
313 if (best) {
314 record_rename_pair(dst_index, best->index, MAX_SCORE);
315 renames++;
317 return renames;
320 static void insert_file_table(struct hashmap *table, int index, struct diff_filespec *filespec)
322 struct file_similarity *entry = xmalloc(sizeof(*entry));
324 entry->index = index;
325 entry->filespec = filespec;
327 hashmap_entry_init(entry, hash_filespec(filespec));
328 hashmap_add(table, entry);
332 * Find exact renames first.
334 * The first round matches up the up-to-date entries,
335 * and then during the second round we try to match
336 * cache-dirty entries as well.
338 static int find_exact_renames(struct diff_options *options)
340 int i, renames = 0;
341 struct hashmap file_table;
343 /* Add all sources to the hash table */
344 hashmap_init(&file_table, NULL, rename_src_nr);
345 for (i = 0; i < rename_src_nr; 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 * but handles the potential overflow case specially (and we
396 * assume at least 32-bit integers)
398 if (rename_limit <= 0 || rename_limit > 32767)
399 rename_limit = 32767;
400 if ((num_create <= rename_limit || num_src <= rename_limit) &&
401 (num_create * num_src <= rename_limit * rename_limit))
402 return 0;
404 options->needed_rename_limit =
405 num_src > num_create ? num_src : num_create;
407 /* Are we running under -C -C? */
408 if (!DIFF_OPT_TST(options, FIND_COPIES_HARDER))
409 return 1;
411 /* Would we bust the limit if we were running under -C? */
412 for (num_src = i = 0; i < rename_src_nr; i++) {
413 if (diff_unmodified_pair(rename_src[i].p))
414 continue;
415 num_src++;
417 if ((num_create <= rename_limit || num_src <= rename_limit) &&
418 (num_create * num_src <= rename_limit * rename_limit))
419 return 2;
420 return 1;
423 static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, int copies)
425 int count = 0, i;
427 for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
428 struct diff_rename_dst *dst;
430 if ((mx[i].dst < 0) ||
431 (mx[i].score < minimum_score))
432 break; /* there is no more usable pair. */
433 dst = &rename_dst[mx[i].dst];
434 if (dst->pair)
435 continue; /* already done, either exact or fuzzy. */
436 if (!copies && rename_src[mx[i].src].p->one->rename_used)
437 continue;
438 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
439 count++;
441 return count;
444 void diffcore_rename(struct diff_options *options)
446 int detect_rename = options->detect_rename;
447 int minimum_score = options->rename_score;
448 struct diff_queue_struct *q = &diff_queued_diff;
449 struct diff_queue_struct outq;
450 struct diff_score *mx;
451 int i, j, rename_count, skip_unmodified = 0;
452 int num_create, dst_cnt;
453 struct progress *progress = NULL;
455 if (!minimum_score)
456 minimum_score = DEFAULT_RENAME_SCORE;
458 for (i = 0; i < q->nr; i++) {
459 struct diff_filepair *p = q->queue[i];
460 if (!DIFF_FILE_VALID(p->one)) {
461 if (!DIFF_FILE_VALID(p->two))
462 continue; /* unmerged */
463 else if (options->single_follow &&
464 strcmp(options->single_follow, p->two->path))
465 continue; /* not interested */
466 else if (!DIFF_OPT_TST(options, RENAME_EMPTY) &&
467 is_empty_blob_sha1(p->two->sha1))
468 continue;
469 else if (add_rename_dst(p->two) < 0) {
470 warning("skipping rename detection, detected"
471 " duplicate destination '%s'",
472 p->two->path);
473 goto cleanup;
476 else if (!DIFF_OPT_TST(options, RENAME_EMPTY) &&
477 is_empty_blob_sha1(p->one->sha1))
478 continue;
479 else if (!DIFF_PAIR_UNMERGED(p) && !DIFF_FILE_VALID(p->two)) {
481 * If the source is a broken "delete", and
482 * they did not really want to get broken,
483 * that means the source actually stays.
484 * So we increment the "rename_used" score
485 * by one, to indicate ourselves as a user
487 if (p->broken_pair && !p->score)
488 p->one->rename_used++;
489 register_rename_src(p);
491 else if (detect_rename == DIFF_DETECT_COPY) {
493 * Increment the "rename_used" score by
494 * one, to indicate ourselves as a user.
496 p->one->rename_used++;
497 register_rename_src(p);
500 if (rename_dst_nr == 0 || rename_src_nr == 0)
501 goto cleanup; /* nothing to do */
504 * We really want to cull the candidates list early
505 * with cheap tests in order to avoid doing deltas.
507 rename_count = find_exact_renames(options);
509 /* Did we only want exact renames? */
510 if (minimum_score == MAX_SCORE)
511 goto cleanup;
514 * Calculate how many renames are left (but all the source
515 * files still remain as options for rename/copies!)
517 num_create = (rename_dst_nr - rename_count);
519 /* All done? */
520 if (!num_create)
521 goto cleanup;
523 switch (too_many_rename_candidates(num_create, options)) {
524 case 1:
525 goto cleanup;
526 case 2:
527 options->degraded_cc_to_c = 1;
528 skip_unmodified = 1;
529 break;
530 default:
531 break;
534 if (options->show_rename_progress) {
535 progress = start_progress_delay(
536 _("Performing inexact rename detection"),
537 rename_dst_nr * rename_src_nr, 50, 1);
540 mx = xcalloc(num_create * NUM_CANDIDATE_PER_DST, sizeof(*mx));
541 for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
542 struct diff_filespec *two = rename_dst[i].two;
543 struct diff_score *m;
545 if (rename_dst[i].pair)
546 continue; /* dealt with exact match already. */
548 m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST];
549 for (j = 0; j < NUM_CANDIDATE_PER_DST; j++)
550 m[j].dst = -1;
552 for (j = 0; j < rename_src_nr; j++) {
553 struct diff_filespec *one = rename_src[j].p->one;
554 struct diff_score this_src;
556 if (skip_unmodified &&
557 diff_unmodified_pair(rename_src[j].p))
558 continue;
560 this_src.score = estimate_similarity(one, two,
561 minimum_score);
562 this_src.name_score = basename_same(one, two);
563 this_src.dst = i;
564 this_src.src = j;
565 record_if_better(m, &this_src);
567 * Once we run estimate_similarity,
568 * We do not need the text anymore.
570 diff_free_filespec_blob(one);
571 diff_free_filespec_blob(two);
573 dst_cnt++;
574 display_progress(progress, (i+1)*rename_src_nr);
576 stop_progress(&progress);
578 /* cost matrix sorted by most to least similar pair */
579 qsort(mx, dst_cnt * NUM_CANDIDATE_PER_DST, sizeof(*mx), score_compare);
581 rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
582 if (detect_rename == DIFF_DETECT_COPY)
583 rename_count += find_renames(mx, dst_cnt, minimum_score, 1);
584 free(mx);
586 cleanup:
587 /* At this point, we have found some renames and copies and they
588 * are recorded in rename_dst. The original list is still in *q.
590 DIFF_QUEUE_CLEAR(&outq);
591 for (i = 0; i < q->nr; i++) {
592 struct diff_filepair *p = q->queue[i];
593 struct diff_filepair *pair_to_free = NULL;
595 if (DIFF_PAIR_UNMERGED(p)) {
596 diff_q(&outq, p);
598 else if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
600 * Creation
602 * We would output this create record if it has
603 * not been turned into a rename/copy already.
605 struct diff_rename_dst *dst = locate_rename_dst(p->two);
606 if (dst && dst->pair) {
607 diff_q(&outq, dst->pair);
608 pair_to_free = p;
610 else
611 /* no matching rename/copy source, so
612 * record this as a creation.
614 diff_q(&outq, p);
616 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
618 * Deletion
620 * We would output this delete record if:
622 * (1) this is a broken delete and the counterpart
623 * broken create remains in the output; or
624 * (2) this is not a broken delete, and rename_dst
625 * does not have a rename/copy to move p->one->path
626 * out of existence.
628 * Otherwise, the counterpart broken create
629 * has been turned into a rename-edit; or
630 * delete did not have a matching create to
631 * begin with.
633 if (DIFF_PAIR_BROKEN(p)) {
634 /* broken delete */
635 struct diff_rename_dst *dst = locate_rename_dst(p->one);
636 if (dst && dst->pair)
637 /* counterpart is now rename/copy */
638 pair_to_free = p;
640 else {
641 if (p->one->rename_used)
642 /* this path remains */
643 pair_to_free = p;
646 if (pair_to_free)
648 else
649 diff_q(&outq, p);
651 else if (!diff_unmodified_pair(p))
652 /* all the usual ones need to be kept */
653 diff_q(&outq, p);
654 else
655 /* no need to keep unmodified pairs */
656 pair_to_free = p;
658 if (pair_to_free)
659 diff_free_filepair(pair_to_free);
661 diff_debug_queue("done copying original", &outq);
663 free(q->queue);
664 *q = outq;
665 diff_debug_queue("done collapsing", q);
667 for (i = 0; i < rename_dst_nr; i++)
668 free_filespec(rename_dst[i].two);
670 free(rename_dst);
671 rename_dst = NULL;
672 rename_dst_nr = rename_dst_alloc = 0;
673 free(rename_src);
674 rename_src = NULL;
675 rename_src_nr = rename_src_alloc = 0;
676 return;