]> git.ipfire.org Git - thirdparty/git.git/blob - diffcore-rename.c
t3905: move all commands into test cases
[thirdparty/git.git] / diffcore-rename.c
1 /*
2 *
3 * Copyright (C) 2005 Junio C Hamano
4 */
5 #include "cache.h"
6 #include "diff.h"
7 #include "diffcore.h"
8 #include "object-store.h"
9 #include "hashmap.h"
10 #include "progress.h"
11 #include "promisor-remote.h"
12 #include "strmap.h"
13
14 /* Table of rename/copy destinations */
15
16 static struct diff_rename_dst {
17 struct diff_filepair *p;
18 struct diff_filespec *filespec_to_free;
19 int is_rename; /* false -> just a create; true -> rename or copy */
20 } *rename_dst;
21 static int rename_dst_nr, rename_dst_alloc;
22 /* Mapping from break source pathname to break destination index */
23 static struct strintmap *break_idx = NULL;
24
25 static struct diff_rename_dst *locate_rename_dst(struct diff_filepair *p)
26 {
27 /* Lookup by p->ONE->path */
28 int idx = break_idx ? strintmap_get(break_idx, p->one->path) : -1;
29 return (idx == -1) ? NULL : &rename_dst[idx];
30 }
31
32 /*
33 * Returns 0 on success, -1 if we found a duplicate.
34 */
35 static int add_rename_dst(struct diff_filepair *p)
36 {
37 ALLOC_GROW(rename_dst, rename_dst_nr + 1, rename_dst_alloc);
38 rename_dst[rename_dst_nr].p = p;
39 rename_dst[rename_dst_nr].filespec_to_free = NULL;
40 rename_dst[rename_dst_nr].is_rename = 0;
41 rename_dst_nr++;
42 return 0;
43 }
44
45 /* Table of rename/copy src files */
46 static struct diff_rename_src {
47 struct diff_filepair *p;
48 unsigned short score; /* to remember the break score */
49 } *rename_src;
50 static int rename_src_nr, rename_src_alloc;
51
52 static void register_rename_src(struct diff_filepair *p)
53 {
54 if (p->broken_pair) {
55 if (!break_idx) {
56 break_idx = xmalloc(sizeof(*break_idx));
57 strintmap_init(break_idx, -1);
58 }
59 strintmap_set(break_idx, p->one->path, rename_dst_nr);
60 }
61
62 ALLOC_GROW(rename_src, rename_src_nr + 1, rename_src_alloc);
63 rename_src[rename_src_nr].p = p;
64 rename_src[rename_src_nr].score = p->score;
65 rename_src_nr++;
66 }
67
68 static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
69 {
70 int src_len = strlen(src->path), dst_len = strlen(dst->path);
71 while (src_len && dst_len) {
72 char c1 = src->path[--src_len];
73 char c2 = dst->path[--dst_len];
74 if (c1 != c2)
75 return 0;
76 if (c1 == '/')
77 return 1;
78 }
79 return (!src_len || src->path[src_len - 1] == '/') &&
80 (!dst_len || dst->path[dst_len - 1] == '/');
81 }
82
83 struct diff_score {
84 int src; /* index in rename_src */
85 int dst; /* index in rename_dst */
86 unsigned short score;
87 short name_score;
88 };
89
90 struct prefetch_options {
91 struct repository *repo;
92 int skip_unmodified;
93 };
94 static void prefetch(void *prefetch_options)
95 {
96 struct prefetch_options *options = prefetch_options;
97 int i;
98 struct oid_array to_fetch = OID_ARRAY_INIT;
99
100 for (i = 0; i < rename_dst_nr; i++) {
101 if (rename_dst[i].p->renamed_pair)
102 /*
103 * The loop in diffcore_rename() will not need these
104 * blobs, so skip prefetching.
105 */
106 continue; /* already found exact match */
107 diff_add_if_missing(options->repo, &to_fetch,
108 rename_dst[i].p->two);
109 }
110 for (i = 0; i < rename_src_nr; i++) {
111 if (options->skip_unmodified &&
112 diff_unmodified_pair(rename_src[i].p))
113 /*
114 * The loop in diffcore_rename() will not need these
115 * blobs, so skip prefetching.
116 */
117 continue;
118 diff_add_if_missing(options->repo, &to_fetch,
119 rename_src[i].p->one);
120 }
121 promisor_remote_get_direct(options->repo, to_fetch.oid, to_fetch.nr);
122 oid_array_clear(&to_fetch);
123 }
124
125 static int estimate_similarity(struct repository *r,
126 struct diff_filespec *src,
127 struct diff_filespec *dst,
128 int minimum_score,
129 int skip_unmodified)
130 {
131 /* src points at a file that existed in the original tree (or
132 * optionally a file in the destination tree) and dst points
133 * at a newly created file. They may be quite similar, in which
134 * case we want to say src is renamed to dst or src is copied into
135 * dst, and then some edit has been applied to dst.
136 *
137 * Compare them and return how similar they are, representing
138 * the score as an integer between 0 and MAX_SCORE.
139 *
140 * When there is an exact match, it is considered a better
141 * match than anything else; the destination does not even
142 * call into this function in that case.
143 */
144 unsigned long max_size, delta_size, base_size, src_copied, literal_added;
145 int score;
146 struct diff_populate_filespec_options dpf_options = {
147 .check_size_only = 1
148 };
149 struct prefetch_options prefetch_options = {r, skip_unmodified};
150
151 if (r == the_repository && has_promisor_remote()) {
152 dpf_options.missing_object_cb = prefetch;
153 dpf_options.missing_object_data = &prefetch_options;
154 }
155
156 /* We deal only with regular files. Symlink renames are handled
157 * only when they are exact matches --- in other words, no edits
158 * after renaming.
159 */
160 if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
161 return 0;
162
163 /*
164 * Need to check that source and destination sizes are
165 * filled in before comparing them.
166 *
167 * If we already have "cnt_data" filled in, we know it's
168 * all good (avoid checking the size for zero, as that
169 * is a possible size - we really should have a flag to
170 * say whether the size is valid or not!)
171 */
172 if (!src->cnt_data &&
173 diff_populate_filespec(r, src, &dpf_options))
174 return 0;
175 if (!dst->cnt_data &&
176 diff_populate_filespec(r, dst, &dpf_options))
177 return 0;
178
179 max_size = ((src->size > dst->size) ? src->size : dst->size);
180 base_size = ((src->size < dst->size) ? src->size : dst->size);
181 delta_size = max_size - base_size;
182
183 /* We would not consider edits that change the file size so
184 * drastically. delta_size must be smaller than
185 * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
186 *
187 * Note that base_size == 0 case is handled here already
188 * and the final score computation below would not have a
189 * divide-by-zero issue.
190 */
191 if (max_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
192 return 0;
193
194 dpf_options.check_size_only = 0;
195
196 if (!src->cnt_data && diff_populate_filespec(r, src, &dpf_options))
197 return 0;
198 if (!dst->cnt_data && diff_populate_filespec(r, dst, &dpf_options))
199 return 0;
200
201 if (diffcore_count_changes(r, src, dst,
202 &src->cnt_data, &dst->cnt_data,
203 &src_copied, &literal_added))
204 return 0;
205
206 /* How similar are they?
207 * what percentage of material in dst are from source?
208 */
209 if (!dst->size)
210 score = 0; /* should not happen */
211 else
212 score = (int)(src_copied * MAX_SCORE / max_size);
213 return score;
214 }
215
216 static void record_rename_pair(int dst_index, int src_index, int score)
217 {
218 struct diff_filepair *src = rename_src[src_index].p;
219 struct diff_filepair *dst = rename_dst[dst_index].p;
220
221 if (dst->renamed_pair)
222 die("internal error: dst already matched.");
223
224 src->one->rename_used++;
225 src->one->count++;
226
227 rename_dst[dst_index].filespec_to_free = dst->one;
228 rename_dst[dst_index].is_rename = 1;
229
230 dst->one = src->one;
231 dst->renamed_pair = 1;
232 if (!strcmp(dst->one->path, dst->two->path))
233 dst->score = rename_src[src_index].score;
234 else
235 dst->score = score;
236 }
237
238 /*
239 * We sort the rename similarity matrix with the score, in descending
240 * order (the most similar first).
241 */
242 static int score_compare(const void *a_, const void *b_)
243 {
244 const struct diff_score *a = a_, *b = b_;
245
246 /* sink the unused ones to the bottom */
247 if (a->dst < 0)
248 return (0 <= b->dst);
249 else if (b->dst < 0)
250 return -1;
251
252 if (a->score == b->score)
253 return b->name_score - a->name_score;
254
255 return b->score - a->score;
256 }
257
258 struct file_similarity {
259 struct hashmap_entry entry;
260 int index;
261 struct diff_filespec *filespec;
262 };
263
264 static unsigned int hash_filespec(struct repository *r,
265 struct diff_filespec *filespec)
266 {
267 if (!filespec->oid_valid) {
268 if (diff_populate_filespec(r, filespec, NULL))
269 return 0;
270 hash_object_file(r->hash_algo, filespec->data, filespec->size,
271 "blob", &filespec->oid);
272 }
273 return oidhash(&filespec->oid);
274 }
275
276 static int find_identical_files(struct hashmap *srcs,
277 int dst_index,
278 struct diff_options *options)
279 {
280 int renames = 0;
281 struct diff_filespec *target = rename_dst[dst_index].p->two;
282 struct file_similarity *p, *best = NULL;
283 int i = 100, best_score = -1;
284 unsigned int hash = hash_filespec(options->repo, target);
285
286 /*
287 * Find the best source match for specified destination.
288 */
289 p = hashmap_get_entry_from_hash(srcs, hash, NULL,
290 struct file_similarity, entry);
291 hashmap_for_each_entry_from(srcs, p, entry) {
292 int score;
293 struct diff_filespec *source = p->filespec;
294
295 /* False hash collision? */
296 if (!oideq(&source->oid, &target->oid))
297 continue;
298 /* Non-regular files? If so, the modes must match! */
299 if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
300 if (source->mode != target->mode)
301 continue;
302 }
303 /* Give higher scores to sources that haven't been used already */
304 score = !source->rename_used;
305 if (source->rename_used && options->detect_rename != DIFF_DETECT_COPY)
306 continue;
307 score += basename_same(source, target);
308 if (score > best_score) {
309 best = p;
310 best_score = score;
311 if (score == 2)
312 break;
313 }
314
315 /* Too many identical alternatives? Pick one */
316 if (!--i)
317 break;
318 }
319 if (best) {
320 record_rename_pair(dst_index, best->index, MAX_SCORE);
321 renames++;
322 }
323 return renames;
324 }
325
326 static void insert_file_table(struct repository *r,
327 struct hashmap *table, int index,
328 struct diff_filespec *filespec)
329 {
330 struct file_similarity *entry = xmalloc(sizeof(*entry));
331
332 entry->index = index;
333 entry->filespec = filespec;
334
335 hashmap_entry_init(&entry->entry, hash_filespec(r, filespec));
336 hashmap_add(table, &entry->entry);
337 }
338
339 /*
340 * Find exact renames first.
341 *
342 * The first round matches up the up-to-date entries,
343 * and then during the second round we try to match
344 * cache-dirty entries as well.
345 */
346 static int find_exact_renames(struct diff_options *options)
347 {
348 int i, renames = 0;
349 struct hashmap file_table;
350
351 /* Add all sources to the hash table in reverse order, because
352 * later on they will be retrieved in LIFO order.
353 */
354 hashmap_init(&file_table, NULL, NULL, rename_src_nr);
355 for (i = rename_src_nr-1; i >= 0; i--)
356 insert_file_table(options->repo,
357 &file_table, i,
358 rename_src[i].p->one);
359
360 /* Walk the destinations and find best source match */
361 for (i = 0; i < rename_dst_nr; i++)
362 renames += find_identical_files(&file_table, i, options);
363
364 /* Free the hash data structure and entries */
365 hashmap_clear_and_free(&file_table, struct file_similarity, entry);
366
367 return renames;
368 }
369
370 #define NUM_CANDIDATE_PER_DST 4
371 static void record_if_better(struct diff_score m[], struct diff_score *o)
372 {
373 int i, worst;
374
375 /* find the worst one */
376 worst = 0;
377 for (i = 1; i < NUM_CANDIDATE_PER_DST; i++)
378 if (score_compare(&m[i], &m[worst]) > 0)
379 worst = i;
380
381 /* is it better than the worst one? */
382 if (score_compare(&m[worst], o) > 0)
383 m[worst] = *o;
384 }
385
386 /*
387 * Returns:
388 * 0 if we are under the limit;
389 * 1 if we need to disable inexact rename detection;
390 * 2 if we would be under the limit if we were given -C instead of -C -C.
391 */
392 static int too_many_rename_candidates(int num_destinations, int num_sources,
393 struct diff_options *options)
394 {
395 int rename_limit = options->rename_limit;
396 int i, limited_sources;
397
398 options->needed_rename_limit = 0;
399
400 /*
401 * This basically does a test for the rename matrix not
402 * growing larger than a "rename_limit" square matrix, ie:
403 *
404 * num_destinations * num_sources > rename_limit * rename_limit
405 *
406 * We use st_mult() to check overflow conditions; in the
407 * exceptional circumstance that size_t isn't large enough to hold
408 * the multiplication, the system won't be able to allocate enough
409 * memory for the matrix anyway.
410 */
411 if (rename_limit <= 0)
412 rename_limit = 32767;
413 if (st_mult(num_destinations, num_sources)
414 <= st_mult(rename_limit, rename_limit))
415 return 0;
416
417 options->needed_rename_limit =
418 num_sources > num_destinations ? num_sources : num_destinations;
419
420 /* Are we running under -C -C? */
421 if (!options->flags.find_copies_harder)
422 return 1;
423
424 /* Would we bust the limit if we were running under -C? */
425 for (limited_sources = i = 0; i < num_sources; i++) {
426 if (diff_unmodified_pair(rename_src[i].p))
427 continue;
428 limited_sources++;
429 }
430 if (st_mult(num_destinations, limited_sources)
431 <= st_mult(rename_limit, rename_limit))
432 return 2;
433 return 1;
434 }
435
436 static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, int copies)
437 {
438 int count = 0, i;
439
440 for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
441 struct diff_rename_dst *dst;
442
443 if ((mx[i].dst < 0) ||
444 (mx[i].score < minimum_score))
445 break; /* there is no more usable pair. */
446 dst = &rename_dst[mx[i].dst];
447 if (dst->is_rename)
448 continue; /* already done, either exact or fuzzy. */
449 if (!copies && rename_src[mx[i].src].p->one->rename_used)
450 continue;
451 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
452 count++;
453 }
454 return count;
455 }
456
457 void diffcore_rename(struct diff_options *options)
458 {
459 int detect_rename = options->detect_rename;
460 int minimum_score = options->rename_score;
461 struct diff_queue_struct *q = &diff_queued_diff;
462 struct diff_queue_struct outq;
463 struct diff_score *mx;
464 int i, j, rename_count, skip_unmodified = 0;
465 int num_destinations, dst_cnt;
466 struct progress *progress = NULL;
467
468 if (!minimum_score)
469 minimum_score = DEFAULT_RENAME_SCORE;
470
471 for (i = 0; i < q->nr; i++) {
472 struct diff_filepair *p = q->queue[i];
473 if (!DIFF_FILE_VALID(p->one)) {
474 if (!DIFF_FILE_VALID(p->two))
475 continue; /* unmerged */
476 else if (options->single_follow &&
477 strcmp(options->single_follow, p->two->path))
478 continue; /* not interested */
479 else if (!options->flags.rename_empty &&
480 is_empty_blob_oid(&p->two->oid))
481 continue;
482 else if (add_rename_dst(p) < 0) {
483 warning("skipping rename detection, detected"
484 " duplicate destination '%s'",
485 p->two->path);
486 goto cleanup;
487 }
488 }
489 else if (!options->flags.rename_empty &&
490 is_empty_blob_oid(&p->one->oid))
491 continue;
492 else if (!DIFF_PAIR_UNMERGED(p) && !DIFF_FILE_VALID(p->two)) {
493 /*
494 * If the source is a broken "delete", and
495 * they did not really want to get broken,
496 * that means the source actually stays.
497 * So we increment the "rename_used" score
498 * by one, to indicate ourselves as a user
499 */
500 if (p->broken_pair && !p->score)
501 p->one->rename_used++;
502 register_rename_src(p);
503 }
504 else if (detect_rename == DIFF_DETECT_COPY) {
505 /*
506 * Increment the "rename_used" score by
507 * one, to indicate ourselves as a user.
508 */
509 p->one->rename_used++;
510 register_rename_src(p);
511 }
512 }
513 if (rename_dst_nr == 0 || rename_src_nr == 0)
514 goto cleanup; /* nothing to do */
515
516 /*
517 * We really want to cull the candidates list early
518 * with cheap tests in order to avoid doing deltas.
519 */
520 rename_count = find_exact_renames(options);
521
522 /* Did we only want exact renames? */
523 if (minimum_score == MAX_SCORE)
524 goto cleanup;
525
526 /*
527 * Calculate how many renames are left (but all the source
528 * files still remain as options for rename/copies!)
529 */
530 num_destinations = (rename_dst_nr - rename_count);
531
532 /* All done? */
533 if (!num_destinations)
534 goto cleanup;
535
536 switch (too_many_rename_candidates(num_destinations, rename_src_nr,
537 options)) {
538 case 1:
539 goto cleanup;
540 case 2:
541 options->degraded_cc_to_c = 1;
542 skip_unmodified = 1;
543 break;
544 default:
545 break;
546 }
547
548 if (options->show_rename_progress) {
549 progress = start_delayed_progress(
550 _("Performing inexact rename detection"),
551 (uint64_t)num_destinations * (uint64_t)rename_src_nr);
552 }
553
554 mx = xcalloc(st_mult(NUM_CANDIDATE_PER_DST, num_destinations),
555 sizeof(*mx));
556 for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
557 struct diff_filespec *two = rename_dst[i].p->two;
558 struct diff_score *m;
559
560 if (rename_dst[i].is_rename)
561 continue; /* dealt with exact match already. */
562
563 m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST];
564 for (j = 0; j < NUM_CANDIDATE_PER_DST; j++)
565 m[j].dst = -1;
566
567 for (j = 0; j < rename_src_nr; j++) {
568 struct diff_filespec *one = rename_src[j].p->one;
569 struct diff_score this_src;
570
571 if (skip_unmodified &&
572 diff_unmodified_pair(rename_src[j].p))
573 continue;
574
575 this_src.score = estimate_similarity(options->repo,
576 one, two,
577 minimum_score,
578 skip_unmodified);
579 this_src.name_score = basename_same(one, two);
580 this_src.dst = i;
581 this_src.src = j;
582 record_if_better(m, &this_src);
583 /*
584 * Once we run estimate_similarity,
585 * We do not need the text anymore.
586 */
587 diff_free_filespec_blob(one);
588 diff_free_filespec_blob(two);
589 }
590 dst_cnt++;
591 display_progress(progress,
592 (uint64_t)dst_cnt * (uint64_t)rename_src_nr);
593 }
594 stop_progress(&progress);
595
596 /* cost matrix sorted by most to least similar pair */
597 STABLE_QSORT(mx, dst_cnt * NUM_CANDIDATE_PER_DST, score_compare);
598
599 rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
600 if (detect_rename == DIFF_DETECT_COPY)
601 rename_count += find_renames(mx, dst_cnt, minimum_score, 1);
602 free(mx);
603
604 cleanup:
605 /* At this point, we have found some renames and copies and they
606 * are recorded in rename_dst. The original list is still in *q.
607 */
608 DIFF_QUEUE_CLEAR(&outq);
609 for (i = 0; i < q->nr; i++) {
610 struct diff_filepair *p = q->queue[i];
611 struct diff_filepair *pair_to_free = NULL;
612
613 if (DIFF_PAIR_UNMERGED(p)) {
614 diff_q(&outq, p);
615 }
616 else if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
617 /* Creation */
618 diff_q(&outq, p);
619 }
620 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
621 /*
622 * Deletion
623 *
624 * We would output this delete record if:
625 *
626 * (1) this is a broken delete and the counterpart
627 * broken create remains in the output; or
628 * (2) this is not a broken delete, and rename_dst
629 * does not have a rename/copy to move p->one->path
630 * out of existence.
631 *
632 * Otherwise, the counterpart broken create
633 * has been turned into a rename-edit; or
634 * delete did not have a matching create to
635 * begin with.
636 */
637 if (DIFF_PAIR_BROKEN(p)) {
638 /* broken delete */
639 struct diff_rename_dst *dst = locate_rename_dst(p);
640 if (!dst)
641 BUG("tracking failed somehow; failed to find associated dst for broken pair");
642 if (dst->is_rename)
643 /* counterpart is now rename/copy */
644 pair_to_free = p;
645 }
646 else {
647 if (p->one->rename_used)
648 /* this path remains */
649 pair_to_free = p;
650 }
651
652 if (!pair_to_free)
653 diff_q(&outq, p);
654 }
655 else if (!diff_unmodified_pair(p))
656 /* all the usual ones need to be kept */
657 diff_q(&outq, p);
658 else
659 /* no need to keep unmodified pairs; FIXME: remove earlier? */
660 pair_to_free = p;
661
662 if (pair_to_free)
663 diff_free_filepair(pair_to_free);
664 }
665 diff_debug_queue("done copying original", &outq);
666
667 free(q->queue);
668 *q = outq;
669 diff_debug_queue("done collapsing", q);
670
671 for (i = 0; i < rename_dst_nr; i++)
672 if (rename_dst[i].filespec_to_free)
673 free_filespec(rename_dst[i].filespec_to_free);
674
675 FREE_AND_NULL(rename_dst);
676 rename_dst_nr = rename_dst_alloc = 0;
677 FREE_AND_NULL(rename_src);
678 rename_src_nr = rename_src_alloc = 0;
679 if (break_idx) {
680 strintmap_clear(break_idx);
681 FREE_AND_NULL(break_idx);
682 }
683 return;
684 }