gitweb: use new Git::Repo API, and add optional caching
[git/gitweb-caching.git] / diffcore-rename.c
blob1b2ebb40014d820fe4fb679509ab694d453be7b4
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"
9 /* Table of rename/copy destinations */
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;
17 static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
18 int insert_ok)
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 dst;
30 if (cmp < 0) {
31 last = next;
32 continue;
34 first = next+1;
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));
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]);
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;
62 static struct diff_rename_src *register_rename_src(struct diff_filespec *one,
63 unsigned short score)
65 int first, last;
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;
79 first = next+1;
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));
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]);
97 static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
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;
108 return (!src_len || src->path[src_len - 1] == '/') &&
109 (!dst_len || dst->path[dst_len - 1] == '/');
112 struct diff_score {
113 int src; /* index in rename_src */
114 int dst; /* index in rename_dst */
115 unsigned short score;
116 short name_score;
119 static int estimate_similarity(struct diff_filespec *src,
120 struct diff_filespec *dst,
121 int minimum_score)
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.
129 * Compare them and return how similar they are, representing
130 * the score as an integer between 0 and MAX_SCORE.
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.
136 unsigned long max_size, delta_size, base_size, src_copied, literal_added;
137 unsigned long delta_limit;
138 int score;
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.
144 if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
145 return 0;
148 * Need to check that source and destination sizes are
149 * filled in before comparing them.
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!)
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;
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;
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).
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.
173 if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
174 return 0;
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;
184 /* How similar are they?
185 * what percentage of material in dst are from source?
187 if (!dst->size)
188 score = 0; /* should not happen */
189 else
190 score = (int)(src_copied * MAX_SCORE / max_size);
191 return score;
194 static void record_rename_pair(int dst_index, int src_index, int score)
196 struct diff_filespec *src, *dst;
197 struct diff_filepair *dp;
199 if (rename_dst[dst_index].pair)
200 die("internal error: dst already matched.");
202 src = rename_src[src_index].one;
203 src->rename_used++;
204 src->count++;
206 dst = rename_dst[dst_index].two;
207 dst->count++;
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;
219 * We sort the rename similarity matrix with the score, in descending
220 * order (the most similar first).
222 static int score_compare(const void *a_, const void *b_)
224 const struct diff_score *a = a_, *b = b_;
226 /* sink the unused ones to the bottom */
227 if (a->dst < 0)
228 return (0 <= b->dst);
229 else if (b->dst < 0)
230 return -1;
232 if (a->score == b->score)
233 return b->name_score - a->name_score;
235 return b->score - a->score;
238 struct file_similarity {
239 int src_dst, index;
240 struct diff_filespec *filespec;
241 struct file_similarity *next;
244 static int find_identical_files(struct file_similarity *src,
245 struct file_similarity *dst)
247 int renames = 0;
250 * Walk over all the destinations ...
252 do {
253 struct diff_filespec *target = dst->filespec;
254 struct file_similarity *p, *best;
255 int i = 100, best_score = -1;
258 * .. to find the best source match
260 best = NULL;
261 for (p = src; p; p = p->next) {
262 int score;
263 struct diff_filespec *source = p->filespec;
265 /* False hash collission? */
266 if (hashcmp(source->sha1, target->sha1))
267 continue;
268 /* Non-regular files? If so, the modes must match! */
269 if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
270 if (source->mode != target->mode)
271 continue;
273 /* Give higher scores to sources that haven't been used already */
274 score = !source->rename_used;
275 score += basename_same(source, target);
276 if (score > best_score) {
277 best = p;
278 best_score = score;
279 if (score == 2)
280 break;
283 /* Too many identical alternatives? Pick one */
284 if (!--i)
285 break;
287 if (best) {
288 record_rename_pair(dst->index, best->index, MAX_SCORE);
289 renames++;
291 } while ((dst = dst->next) != NULL);
292 return renames;
295 static void free_similarity_list(struct file_similarity *p)
297 while (p) {
298 struct file_similarity *entry = p;
299 p = p->next;
300 free(entry);
304 static int find_same_files(void *ptr)
306 int ret;
307 struct file_similarity *p = ptr;
308 struct file_similarity *src = NULL, *dst = NULL;
310 /* Split the hash list up into sources and destinations */
311 do {
312 struct file_similarity *entry = p;
313 p = p->next;
314 if (entry->src_dst < 0) {
315 entry->next = src;
316 src = entry;
317 } else {
318 entry->next = dst;
319 dst = entry;
321 } while (p);
324 * If we have both sources *and* destinations, see if
325 * we can match them up
327 ret = (src && dst) ? find_identical_files(src, dst) : 0;
329 /* Free the hashes and return the number of renames found */
330 free_similarity_list(src);
331 free_similarity_list(dst);
332 return ret;
335 static unsigned int hash_filespec(struct diff_filespec *filespec)
337 unsigned int hash;
338 if (!filespec->sha1_valid) {
339 if (diff_populate_filespec(filespec, 0))
340 return 0;
341 hash_sha1_file(filespec->data, filespec->size, "blob", filespec->sha1);
343 memcpy(&hash, filespec->sha1, sizeof(hash));
344 return hash;
347 static void insert_file_table(struct hash_table *table, int src_dst, int index, struct diff_filespec *filespec)
349 void **pos;
350 unsigned int hash;
351 struct file_similarity *entry = xmalloc(sizeof(*entry));
353 entry->src_dst = src_dst;
354 entry->index = index;
355 entry->filespec = filespec;
356 entry->next = NULL;
358 hash = hash_filespec(filespec);
359 pos = insert_hash(hash, entry, table);
361 /* We already had an entry there? */
362 if (pos) {
363 entry->next = *pos;
364 *pos = entry;
369 * Find exact renames first.
371 * The first round matches up the up-to-date entries,
372 * and then during the second round we try to match
373 * cache-dirty entries as well.
375 static int find_exact_renames(void)
377 int i;
378 struct hash_table file_table;
380 init_hash(&file_table);
381 for (i = 0; i < rename_src_nr; i++)
382 insert_file_table(&file_table, -1, i, rename_src[i].one);
384 for (i = 0; i < rename_dst_nr; i++)
385 insert_file_table(&file_table, 1, i, rename_dst[i].two);
387 /* Find the renames */
388 i = for_each_hash(&file_table, find_same_files);
390 /* .. and free the hash data structure */
391 free_hash(&file_table);
393 return i;
396 #define NUM_CANDIDATE_PER_DST 4
397 static void record_if_better(struct diff_score m[], struct diff_score *o)
399 int i, worst;
401 /* find the worst one */
402 worst = 0;
403 for (i = 1; i < NUM_CANDIDATE_PER_DST; i++)
404 if (score_compare(&m[i], &m[worst]) > 0)
405 worst = i;
407 /* is it better than the worst one? */
408 if (score_compare(&m[worst], o) > 0)
409 m[worst] = *o;
412 void diffcore_rename(struct diff_options *options)
414 int detect_rename = options->detect_rename;
415 int minimum_score = options->rename_score;
416 int rename_limit = options->rename_limit;
417 struct diff_queue_struct *q = &diff_queued_diff;
418 struct diff_queue_struct outq;
419 struct diff_score *mx;
420 int i, j, rename_count;
421 int num_create, num_src, dst_cnt;
423 if (!minimum_score)
424 minimum_score = DEFAULT_RENAME_SCORE;
426 for (i = 0; i < q->nr; i++) {
427 struct diff_filepair *p = q->queue[i];
428 if (!DIFF_FILE_VALID(p->one)) {
429 if (!DIFF_FILE_VALID(p->two))
430 continue; /* unmerged */
431 else if (options->single_follow &&
432 strcmp(options->single_follow, p->two->path))
433 continue; /* not interested */
434 else
435 locate_rename_dst(p->two, 1);
437 else if (!DIFF_FILE_VALID(p->two)) {
439 * If the source is a broken "delete", and
440 * they did not really want to get broken,
441 * that means the source actually stays.
442 * So we increment the "rename_used" score
443 * by one, to indicate ourselves as a user
445 if (p->broken_pair && !p->score)
446 p->one->rename_used++;
447 register_rename_src(p->one, p->score);
449 else if (detect_rename == DIFF_DETECT_COPY) {
451 * Increment the "rename_used" score by
452 * one, to indicate ourselves as a user.
454 p->one->rename_used++;
455 register_rename_src(p->one, p->score);
458 if (rename_dst_nr == 0 || rename_src_nr == 0)
459 goto cleanup; /* nothing to do */
462 * We really want to cull the candidates list early
463 * with cheap tests in order to avoid doing deltas.
465 rename_count = find_exact_renames();
467 /* Did we only want exact renames? */
468 if (minimum_score == MAX_SCORE)
469 goto cleanup;
472 * Calculate how many renames are left (but all the source
473 * files still remain as options for rename/copies!)
475 num_create = (rename_dst_nr - rename_count);
476 num_src = rename_src_nr;
478 /* All done? */
479 if (!num_create)
480 goto cleanup;
483 * This basically does a test for the rename matrix not
484 * growing larger than a "rename_limit" square matrix, ie:
486 * num_create * num_src > rename_limit * rename_limit
488 * but handles the potential overflow case specially (and we
489 * assume at least 32-bit integers)
491 if (rename_limit <= 0 || rename_limit > 32767)
492 rename_limit = 32767;
493 if ((num_create > rename_limit && num_src > rename_limit) ||
494 (num_create * num_src > rename_limit * rename_limit)) {
495 if (options->warn_on_too_large_rename)
496 warning("too many files, skipping inexact rename detection");
497 goto cleanup;
500 mx = xcalloc(num_create * NUM_CANDIDATE_PER_DST, sizeof(*mx));
501 for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
502 struct diff_filespec *two = rename_dst[i].two;
503 struct diff_score *m;
505 if (rename_dst[i].pair)
506 continue; /* dealt with exact match already. */
508 m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST];
509 for (j = 0; j < NUM_CANDIDATE_PER_DST; j++)
510 m[j].dst = -1;
512 for (j = 0; j < rename_src_nr; j++) {
513 struct diff_filespec *one = rename_src[j].one;
514 struct diff_score this_src;
515 this_src.score = estimate_similarity(one, two,
516 minimum_score);
517 this_src.name_score = basename_same(one, two);
518 this_src.dst = i;
519 this_src.src = j;
520 record_if_better(m, &this_src);
521 diff_free_filespec_blob(one);
523 /* We do not need the text anymore */
524 diff_free_filespec_blob(two);
525 dst_cnt++;
528 /* cost matrix sorted by most to least similar pair */
529 qsort(mx, dst_cnt * NUM_CANDIDATE_PER_DST, sizeof(*mx), score_compare);
531 for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
532 struct diff_rename_dst *dst;
534 if ((mx[i].dst < 0) ||
535 (mx[i].score < minimum_score))
536 break; /* there is no more usable pair. */
537 dst = &rename_dst[mx[i].dst];
538 if (dst->pair)
539 continue; /* already done, either exact or fuzzy. */
540 if (rename_src[mx[i].src].one->rename_used)
541 continue;
542 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
543 rename_count++;
546 for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
547 struct diff_rename_dst *dst;
549 if ((mx[i].dst < 0) ||
550 (mx[i].score < minimum_score))
551 break; /* there is no more usable pair. */
552 dst = &rename_dst[mx[i].dst];
553 if (dst->pair)
554 continue; /* already done, either exact or fuzzy. */
555 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
556 rename_count++;
558 free(mx);
560 cleanup:
561 /* At this point, we have found some renames and copies and they
562 * are recorded in rename_dst. The original list is still in *q.
564 outq.queue = NULL;
565 outq.nr = outq.alloc = 0;
566 for (i = 0; i < q->nr; i++) {
567 struct diff_filepair *p = q->queue[i];
568 struct diff_filepair *pair_to_free = NULL;
570 if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
572 * Creation
574 * We would output this create record if it has
575 * not been turned into a rename/copy already.
577 struct diff_rename_dst *dst =
578 locate_rename_dst(p->two, 0);
579 if (dst && dst->pair) {
580 diff_q(&outq, dst->pair);
581 pair_to_free = p;
583 else
584 /* no matching rename/copy source, so
585 * record this as a creation.
587 diff_q(&outq, p);
589 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
591 * Deletion
593 * We would output this delete record if:
595 * (1) this is a broken delete and the counterpart
596 * broken create remains in the output; or
597 * (2) this is not a broken delete, and rename_dst
598 * does not have a rename/copy to move p->one->path
599 * out of existence.
601 * Otherwise, the counterpart broken create
602 * has been turned into a rename-edit; or
603 * delete did not have a matching create to
604 * begin with.
606 if (DIFF_PAIR_BROKEN(p)) {
607 /* broken delete */
608 struct diff_rename_dst *dst =
609 locate_rename_dst(p->one, 0);
610 if (dst && dst->pair)
611 /* counterpart is now rename/copy */
612 pair_to_free = p;
614 else {
615 if (p->one->rename_used)
616 /* this path remains */
617 pair_to_free = p;
620 if (pair_to_free)
622 else
623 diff_q(&outq, p);
625 else if (!diff_unmodified_pair(p))
626 /* all the usual ones need to be kept */
627 diff_q(&outq, p);
628 else
629 /* no need to keep unmodified pairs */
630 pair_to_free = p;
632 if (pair_to_free)
633 diff_free_filepair(pair_to_free);
635 diff_debug_queue("done copying original", &outq);
637 free(q->queue);
638 *q = outq;
639 diff_debug_queue("done collapsing", q);
641 for (i = 0; i < rename_dst_nr; i++)
642 free_filespec(rename_dst[i].two);
644 free(rename_dst);
645 rename_dst = NULL;
646 rename_dst_nr = rename_dst_alloc = 0;
647 free(rename_src);
648 rename_src = NULL;
649 rename_src_nr = rename_src_alloc = 0;
650 return;