Do linear-time/space rename logic for exact renames
[git/git.git] / diffcore-rename.c
CommitLineData
427dcb4b
JH
1/*
2 * Copyright (C) 2005 Junio C Hamano
3 */
4#include "cache.h"
5#include "diff.h"
6#include "diffcore.h"
9027f53c 7#include "hash.h"
427dcb4b 8
25d5ea41
JH
9/* Table of rename/copy destinations */
10
11static struct diff_rename_dst {
12 struct diff_filespec *two;
13 struct diff_filepair *pair;
14} *rename_dst;
15static int rename_dst_nr, rename_dst_alloc;
427dcb4b 16
25d5ea41
JH
17static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
18 int insert_ok)
427dcb4b 19{
25d5ea41
JH
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));
5098bafb
JH
49 rename_dst[first].two = alloc_filespec(two->path);
50 fill_filespec(rename_dst[first].two, two->sha1, two->mode);
25d5ea41
JH
51 rename_dst[first].pair = NULL;
52 return &(rename_dst[first]);
427dcb4b
JH
53}
54
15d061b4 55/* Table of rename/copy src files */
25d5ea41
JH
56static struct diff_rename_src {
57 struct diff_filespec *one;
fc580719 58 unsigned short score; /* to remember the break score */
25d5ea41
JH
59} *rename_src;
60static int rename_src_nr, rename_src_alloc;
427dcb4b 61
15d061b4 62static struct diff_rename_src *register_rename_src(struct diff_filespec *one,
fc580719 63 unsigned short score)
25d5ea41
JH
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 }
15d061b4 81
25d5ea41
JH
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));
427dcb4b 87 }
25d5ea41
JH
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;
fc580719 93 rename_src[first].score = score;
25d5ea41 94 return &(rename_src[first]);
427dcb4b
JH
95}
96
0ce39643
JS
97static 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
427dcb4b 112struct diff_score {
25d5ea41
JH
113 int src; /* index in rename_src */
114 int dst; /* index in rename_dst */
427dcb4b 115 int score;
cfc0aef1 116 int name_score;
427dcb4b
JH
117};
118
119static 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
f0c6b2a2
JH
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.
427dcb4b 135 */
90bd932c 136 unsigned long max_size, delta_size, base_size, src_copied, literal_added;
75c660ac 137 unsigned long delta_limit;
427dcb4b
JH
138 int score;
139
60896c7b
JH
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
90bd932c 147 max_size = ((src->size > dst->size) ? src->size : dst->size);
58b103f5 148 base_size = ((src->size < dst->size) ? src->size : dst->size);
90bd932c 149 delta_size = max_size - base_size;
427dcb4b 150
58b103f5
JH
151 /* We would not consider edits that change the file size so
152 * drastically. delta_size must be smaller than
cd1870ed 153 * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
f0c6b2a2 154 *
58b103f5
JH
155 * Note that base_size == 0 case is handled here already
156 * and the final score computation below would not have a
157 * divide-by-zero issue.
427dcb4b 158 */
cd1870ed 159 if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
427dcb4b
JH
160 return 0;
161
eede7b7d
JK
162 if ((!src->cnt_data && diff_populate_filespec(src, 0))
163 || (!dst->cnt_data && diff_populate_filespec(dst, 0)))
f0c6b2a2
JH
164 return 0; /* error but caught downstream */
165
85976974 166
dc49cd76
SP
167 delta_limit = (unsigned long)
168 (base_size * (MAX_SCORE-minimum_score) / MAX_SCORE);
d8c3d03a 169 if (diffcore_count_changes(src, dst,
c06c7966 170 &src->cnt_data, &dst->cnt_data,
65416758
JH
171 delta_limit,
172 &src_copied, &literal_added))
85976974 173 return 0;
355e76a4 174
1706306a
JH
175 /* How similar are they?
176 * what percentage of material in dst are from source?
427dcb4b 177 */
90bd932c 178 if (!dst->size)
1706306a 179 score = 0; /* should not happen */
cfc0aef1 180 else
dc49cd76 181 score = (int)(src_copied * MAX_SCORE / max_size);
427dcb4b
JH
182 return score;
183}
184
5098bafb 185static void record_rename_pair(int dst_index, int src_index, int score)
427dcb4b 186{
9fb88419 187 struct diff_filespec *src, *dst;
25d5ea41 188 struct diff_filepair *dp;
f7c1512a 189
25d5ea41
JH
190 if (rename_dst[dst_index].pair)
191 die("internal error: dst already matched.");
427dcb4b 192
25d5ea41 193 src = rename_src[src_index].one;
64479711 194 src->rename_used++;
9fb88419 195 src->count++;
427dcb4b 196
25d5ea41 197 dst = rename_dst[dst_index].two;
9fb88419 198 dst->count++;
427dcb4b 199
9fb88419 200 dp = diff_queue(NULL, src, dst);
ef677686 201 dp->renamed_pair = 1;
fc580719
JH
202 if (!strcmp(src->path, dst->path))
203 dp->score = rename_src[src_index].score;
204 else
205 dp->score = score;
25d5ea41 206 rename_dst[dst_index].pair = dp;
427dcb4b
JH
207}
208
209/*
210 * We sort the rename similarity matrix with the score, in descending
15d061b4 211 * order (the most similar first).
427dcb4b
JH
212 */
213static int score_compare(const void *a_, const void *b_)
214{
215 const struct diff_score *a = a_, *b = b_;
cfc0aef1
RS
216
217 if (a->score == b->score)
218 return b->name_score - a->name_score;
219
427dcb4b
JH
220 return b->score - a->score;
221}
222
9027f53c
LT
223struct file_similarity {
224 int src_dst, index;
225 struct diff_filespec *filespec;
226 struct file_similarity *next;
227};
228
229static int find_identical_files(struct file_similarity *src,
230 struct file_similarity *dst)
231{
232 int renames = 0;
233
234 /*
235 * Walk over all the destinations ...
236 */
237 do {
238 struct diff_filespec *one = dst->filespec;
239 struct file_similarity *p, *best;
240 int i = 100;
241
242 /*
243 * .. to find the best source match
244 */
245 best = NULL;
246 for (p = src; p; p = p->next) {
247 struct diff_filespec *two = p->filespec;
248
249 /* False hash collission? */
250 if (hashcmp(one->sha1, two->sha1))
251 continue;
252 /* Non-regular files? If so, the modes must match! */
253 if (!S_ISREG(one->mode) || !S_ISREG(two->mode)) {
254 if (one->mode != two->mode)
255 continue;
256 }
257 best = p;
258 if (basename_same(one, two))
259 break;
260
261 /* Too many identical alternatives? Pick one */
262 if (!--i)
263 break;
264 }
265 if (best) {
266 record_rename_pair(dst->index, best->index, MAX_SCORE);
267 renames++;
268 }
269 } while ((dst = dst->next) != NULL);
270 return renames;
271}
272
273/*
274 * Note: the rest of the rename logic depends on this
275 * phase also populating all the filespecs for any
276 * entry that isn't matched up with an exact rename.
277 */
278static void free_similarity_list(struct file_similarity *p)
279{
280 while (p) {
281 struct file_similarity *entry = p;
282 p = p->next;
283
284 /* Stupid special case, see note above! */
285 diff_populate_filespec(entry->filespec, 0);
286 free(entry);
287 }
288}
289
290static int find_same_files(void *ptr)
291{
292 int ret;
293 struct file_similarity *p = ptr;
294 struct file_similarity *src = NULL, *dst = NULL;
295
296 /* Split the hash list up into sources and destinations */
297 do {
298 struct file_similarity *entry = p;
299 p = p->next;
300 if (entry->src_dst < 0) {
301 entry->next = src;
302 src = entry;
303 } else {
304 entry->next = dst;
305 dst = entry;
306 }
307 } while (p);
308
309 /*
310 * If we have both sources *and* destinations, see if
311 * we can match them up
312 */
313 ret = (src && dst) ? find_identical_files(src, dst) : 0;
314
315 /* Free the hashes and return the number of renames found */
316 free_similarity_list(src);
317 free_similarity_list(dst);
318 return ret;
319}
320
321static unsigned int hash_filespec(struct diff_filespec *filespec)
322{
323 unsigned int hash;
324 if (!filespec->sha1_valid) {
325 if (diff_populate_filespec(filespec, 0))
326 return 0;
327 hash_sha1_file(filespec->data, filespec->size, "blob", filespec->sha1);
328 }
329 memcpy(&hash, filespec->sha1, sizeof(hash));
330 return hash;
331}
332
333static void insert_file_table(struct hash_table *table, int src_dst, int index, struct diff_filespec *filespec)
334{
335 void **pos;
336 unsigned int hash;
337 struct file_similarity *entry = xmalloc(sizeof(*entry));
338
339 entry->src_dst = src_dst;
340 entry->index = index;
341 entry->filespec = filespec;
342 entry->next = NULL;
343
344 hash = hash_filespec(filespec);
345 pos = insert_hash(hash, entry, table);
346
347 /* We already had an entry there? */
348 if (pos) {
349 entry->next = *pos;
350 *pos = entry;
351 }
352}
353
cb1491b6
LT
354/*
355 * Find exact renames first.
356 *
357 * The first round matches up the up-to-date entries,
358 * and then during the second round we try to match
359 * cache-dirty entries as well.
cb1491b6
LT
360 */
361static int find_exact_renames(void)
362{
9027f53c
LT
363 int i;
364 struct hash_table file_table;
cb1491b6 365
9027f53c
LT
366 init_hash(&file_table);
367 for (i = 0; i < rename_src_nr; i++)
368 insert_file_table(&file_table, -1, i, rename_src[i].one);
369
370 for (i = 0; i < rename_dst_nr; i++)
371 insert_file_table(&file_table, 1, i, rename_dst[i].two);
372
373 /* Find the renames */
374 i = for_each_hash(&file_table, find_same_files);
375
376 /* .. and free the hash data structure */
377 free_hash(&file_table);
378
379 return i;
cb1491b6
LT
380}
381
8082d8d3 382void diffcore_rename(struct diff_options *options)
427dcb4b 383{
8082d8d3
JH
384 int detect_rename = options->detect_rename;
385 int minimum_score = options->rename_score;
386 int rename_limit = options->rename_limit;
38c6f780 387 struct diff_queue_struct *q = &diff_queued_diff;
5098bafb 388 struct diff_queue_struct outq;
427dcb4b 389 struct diff_score *mx;
cb1491b6 390 int i, j, rename_count;
25d5ea41 391 int num_create, num_src, dst_cnt;
427dcb4b 392
26dee0ad 393 if (!minimum_score)
f345b0a0 394 minimum_score = DEFAULT_RENAME_SCORE;
427dcb4b 395
427dcb4b 396 for (i = 0; i < q->nr; i++) {
52e95789 397 struct diff_filepair *p = q->queue[i];
2f3f8b21 398 if (!DIFF_FILE_VALID(p->one)) {
81e50eab 399 if (!DIFF_FILE_VALID(p->two))
60896c7b 400 continue; /* unmerged */
2f3f8b21
JH
401 else if (options->single_follow &&
402 strcmp(options->single_follow, p->two->path))
403 continue; /* not interested */
427dcb4b 404 else
25d5ea41 405 locate_rename_dst(p->two, 1);
2f3f8b21 406 }
2210100a 407 else if (!DIFF_FILE_VALID(p->two)) {
64479711
LT
408 /*
409 * If the source is a broken "delete", and
2210100a
JH
410 * they did not really want to get broken,
411 * that means the source actually stays.
64479711
LT
412 * So we increment the "rename_used" score
413 * by one, to indicate ourselves as a user
414 */
415 if (p->broken_pair && !p->score)
416 p->one->rename_used++;
417 register_rename_src(p->one, p->score);
418 }
419 else if (detect_rename == DIFF_DETECT_COPY) {
420 /*
421 * Increment the "rename_used" score by
422 * one, to indicate ourselves as a user.
2210100a 423 */
64479711
LT
424 p->one->rename_used++;
425 register_rename_src(p->one, p->score);
2210100a 426 }
427dcb4b 427 }
0024a549 428 if (rename_dst_nr == 0 || rename_src_nr == 0)
427dcb4b
JH
429 goto cleanup; /* nothing to do */
430
0024a549
LT
431 /*
432 * This basically does a test for the rename matrix not
433 * growing larger than a "rename_limit" square matrix, ie:
434 *
435 * rename_dst_nr * rename_src_nr > rename_limit * rename_limit
436 *
437 * but handles the potential overflow case specially (and we
438 * assume at least 32-bit integers)
439 */
440 if (rename_limit <= 0 || rename_limit > 32767)
441 rename_limit = 32767;
442 if (rename_dst_nr > rename_limit && rename_src_nr > rename_limit)
443 goto cleanup;
444 if (rename_dst_nr * rename_src_nr > rename_limit * rename_limit)
445 goto cleanup;
446
cb1491b6
LT
447 /*
448 * We really want to cull the candidates list early
427dcb4b 449 * with cheap tests in order to avoid doing deltas.
427dcb4b 450 */
cb1491b6 451 rename_count = find_exact_renames();
427dcb4b
JH
452
453 /* Have we run out the created file pool? If so we can avoid
454 * doing the delta matrix altogether.
455 */
5098bafb 456 if (rename_count == rename_dst_nr)
15d061b4 457 goto cleanup;
427dcb4b 458
9f70b806
JH
459 if (minimum_score == MAX_SCORE)
460 goto cleanup;
461
5098bafb 462 num_create = (rename_dst_nr - rename_count);
25d5ea41 463 num_src = rename_src_nr;
427dcb4b 464 mx = xmalloc(sizeof(*mx) * num_create * num_src);
25d5ea41 465 for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
427dcb4b 466 int base = dst_cnt * num_src;
25d5ea41
JH
467 struct diff_filespec *two = rename_dst[i].two;
468 if (rename_dst[i].pair)
427dcb4b 469 continue; /* dealt with exact match already. */
25d5ea41
JH
470 for (j = 0; j < rename_src_nr; j++) {
471 struct diff_filespec *one = rename_src[j].one;
472 struct diff_score *m = &mx[base+j];
473 m->src = j;
474 m->dst = i;
475 m->score = estimate_similarity(one, two,
476 minimum_score);
cfc0aef1 477 m->name_score = basename_same(one, two);
8ae92e63 478 diff_free_filespec_blob(one);
427dcb4b 479 }
2821104d 480 /* We do not need the text anymore */
8ae92e63 481 diff_free_filespec_blob(two);
427dcb4b
JH
482 dst_cnt++;
483 }
484 /* cost matrix sorted by most to least similar pair */
485 qsort(mx, num_create * num_src, sizeof(*mx), score_compare);
486 for (i = 0; i < num_create * num_src; i++) {
25d5ea41
JH
487 struct diff_rename_dst *dst = &rename_dst[mx[i].dst];
488 if (dst->pair)
489 continue; /* already done, either exact or fuzzy. */
427dcb4b 490 if (mx[i].score < minimum_score)
15d061b4 491 break; /* there is no more usable pair. */
5098bafb
JH
492 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
493 rename_count++;
427dcb4b
JH
494 }
495 free(mx);
427dcb4b 496
15d061b4 497 cleanup:
427dcb4b 498 /* At this point, we have found some renames and copies and they
5098bafb 499 * are recorded in rename_dst. The original list is still in *q.
427dcb4b 500 */
25d5ea41
JH
501 outq.queue = NULL;
502 outq.nr = outq.alloc = 0;
427dcb4b 503 for (i = 0; i < q->nr; i++) {
25d5ea41 504 struct diff_filepair *p = q->queue[i];
25d5ea41
JH
505 struct diff_filepair *pair_to_free = NULL;
506
2cd68882
JH
507 if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
508 /*
509 * Creation
510 *
511 * We would output this create record if it has
512 * not been turned into a rename/copy already.
513 */
514 struct diff_rename_dst *dst =
515 locate_rename_dst(p->two, 0);
516 if (dst && dst->pair) {
25d5ea41
JH
517 diff_q(&outq, dst->pair);
518 pair_to_free = p;
519 }
520 else
2cd68882
JH
521 /* no matching rename/copy source, so
522 * record this as a creation.
25d5ea41
JH
523 */
524 diff_q(&outq, p);
427dcb4b 525 }
2cd68882
JH
526 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
527 /*
528 * Deletion
529 *
f345b0a0
JH
530 * We would output this delete record if:
531 *
532 * (1) this is a broken delete and the counterpart
533 * broken create remains in the output; or
5098bafb
JH
534 * (2) this is not a broken delete, and rename_dst
535 * does not have a rename/copy to move p->one->path
536 * out of existence.
f345b0a0
JH
537 *
538 * Otherwise, the counterpart broken create
539 * has been turned into a rename-edit; or
540 * delete did not have a matching create to
541 * begin with.
2cd68882 542 */
f345b0a0
JH
543 if (DIFF_PAIR_BROKEN(p)) {
544 /* broken delete */
545 struct diff_rename_dst *dst =
546 locate_rename_dst(p->one, 0);
547 if (dst && dst->pair)
548 /* counterpart is now rename/copy */
549 pair_to_free = p;
550 }
551 else {
64479711 552 if (p->one->rename_used)
f345b0a0
JH
553 /* this path remains */
554 pair_to_free = p;
555 }
2cd68882
JH
556
557 if (pair_to_free)
558 ;
559 else
560 diff_q(&outq, p);
561 }
25d5ea41 562 else if (!diff_unmodified_pair(p))
15d061b4 563 /* all the usual ones need to be kept */
25d5ea41 564 diff_q(&outq, p);
15d061b4
JH
565 else
566 /* no need to keep unmodified pairs */
567 pair_to_free = p;
568
226406f6
JH
569 if (pair_to_free)
570 diff_free_filepair(pair_to_free);
427dcb4b 571 }
25d5ea41 572 diff_debug_queue("done copying original", &outq);
427dcb4b 573
25d5ea41
JH
574 free(q->queue);
575 *q = outq;
576 diff_debug_queue("done collapsing", q);
427dcb4b 577
9fb88419
LT
578 for (i = 0; i < rename_dst_nr; i++)
579 free_filespec(rename_dst[i].two);
5098bafb 580
25d5ea41
JH
581 free(rename_dst);
582 rename_dst = NULL;
583 rename_dst_nr = rename_dst_alloc = 0;
584 free(rename_src);
585 rename_src = NULL;
586 rename_src_nr = rename_src_alloc = 0;
427dcb4b
JH
587 return;
588}