Ref-count the filespecs used by diffcore
[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"
427dcb4b 7
25d5ea41
JH
8/* Table of rename/copy destinations */
9
10static struct diff_rename_dst {
11 struct diff_filespec *two;
12 struct diff_filepair *pair;
13} *rename_dst;
14static int rename_dst_nr, rename_dst_alloc;
427dcb4b 15
25d5ea41
JH
16static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
17 int insert_ok)
427dcb4b 18{
25d5ea41
JH
19 int first, last;
20
21 first = 0;
22 last = rename_dst_nr;
23 while (last > first) {
24 int next = (last + first) >> 1;
25 struct diff_rename_dst *dst = &(rename_dst[next]);
26 int cmp = strcmp(two->path, dst->two->path);
27 if (!cmp)
28 return dst;
29 if (cmp < 0) {
30 last = next;
31 continue;
32 }
33 first = next+1;
34 }
35 /* not found */
36 if (!insert_ok)
37 return NULL;
38 /* insert to make it at "first" */
39 if (rename_dst_alloc <= rename_dst_nr) {
40 rename_dst_alloc = alloc_nr(rename_dst_alloc);
41 rename_dst = xrealloc(rename_dst,
42 rename_dst_alloc * sizeof(*rename_dst));
43 }
44 rename_dst_nr++;
45 if (first < rename_dst_nr)
46 memmove(rename_dst + first + 1, rename_dst + first,
47 (rename_dst_nr - first - 1) * sizeof(*rename_dst));
5098bafb
JH
48 rename_dst[first].two = alloc_filespec(two->path);
49 fill_filespec(rename_dst[first].two, two->sha1, two->mode);
25d5ea41
JH
50 rename_dst[first].pair = NULL;
51 return &(rename_dst[first]);
427dcb4b
JH
52}
53
15d061b4 54/* Table of rename/copy src files */
25d5ea41
JH
55static struct diff_rename_src {
56 struct diff_filespec *one;
fc580719 57 unsigned short score; /* to remember the break score */
6bac10d8 58 unsigned src_path_left : 1;
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
JH
63 int src_path_left,
64 unsigned short score)
25d5ea41
JH
65{
66 int first, last;
67
68 first = 0;
69 last = rename_src_nr;
70 while (last > first) {
71 int next = (last + first) >> 1;
72 struct diff_rename_src *src = &(rename_src[next]);
73 int cmp = strcmp(one->path, src->one->path);
74 if (!cmp)
75 return src;
76 if (cmp < 0) {
77 last = next;
78 continue;
79 }
80 first = next+1;
81 }
15d061b4 82
25d5ea41
JH
83 /* insert to make it at "first" */
84 if (rename_src_alloc <= rename_src_nr) {
85 rename_src_alloc = alloc_nr(rename_src_alloc);
86 rename_src = xrealloc(rename_src,
87 rename_src_alloc * sizeof(*rename_src));
427dcb4b 88 }
25d5ea41
JH
89 rename_src_nr++;
90 if (first < rename_src_nr)
91 memmove(rename_src + first + 1, rename_src + first,
92 (rename_src_nr - first - 1) * sizeof(*rename_src));
93 rename_src[first].one = one;
fc580719 94 rename_src[first].score = score;
6bac10d8 95 rename_src[first].src_path_left = src_path_left;
25d5ea41 96 return &(rename_src[first]);
427dcb4b
JH
97}
98
17e6019a
JH
99static int is_exact_match(struct diff_filespec *src,
100 struct diff_filespec *dst,
101 int contents_too)
427dcb4b
JH
102{
103 if (src->sha1_valid && dst->sha1_valid &&
a89fccd2 104 !hashcmp(src->sha1, dst->sha1))
427dcb4b 105 return 1;
17e6019a
JH
106 if (!contents_too)
107 return 0;
f0c6b2a2
JH
108 if (diff_populate_filespec(src, 1) || diff_populate_filespec(dst, 1))
109 return 0;
110 if (src->size != dst->size)
111 return 0;
7da41f48
SP
112 if (src->sha1_valid && dst->sha1_valid)
113 return !hashcmp(src->sha1, dst->sha1);
f0c6b2a2 114 if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
427dcb4b
JH
115 return 0;
116 if (src->size == dst->size &&
117 !memcmp(src->data, dst->data, src->size))
118 return 1;
119 return 0;
120}
121
0ce39643
JS
122static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
123{
124 int src_len = strlen(src->path), dst_len = strlen(dst->path);
125 while (src_len && dst_len) {
126 char c1 = src->path[--src_len];
127 char c2 = dst->path[--dst_len];
128 if (c1 != c2)
129 return 0;
130 if (c1 == '/')
131 return 1;
132 }
133 return (!src_len || src->path[src_len - 1] == '/') &&
134 (!dst_len || dst->path[dst_len - 1] == '/');
135}
136
427dcb4b 137struct diff_score {
25d5ea41
JH
138 int src; /* index in rename_src */
139 int dst; /* index in rename_dst */
427dcb4b 140 int score;
cfc0aef1 141 int name_score;
427dcb4b
JH
142};
143
144static int estimate_similarity(struct diff_filespec *src,
145 struct diff_filespec *dst,
146 int minimum_score)
147{
148 /* src points at a file that existed in the original tree (or
149 * optionally a file in the destination tree) and dst points
150 * at a newly created file. They may be quite similar, in which
151 * case we want to say src is renamed to dst or src is copied into
152 * dst, and then some edit has been applied to dst.
153 *
154 * Compare them and return how similar they are, representing
f0c6b2a2
JH
155 * the score as an integer between 0 and MAX_SCORE.
156 *
157 * When there is an exact match, it is considered a better
158 * match than anything else; the destination does not even
159 * call into this function in that case.
427dcb4b 160 */
90bd932c 161 unsigned long max_size, delta_size, base_size, src_copied, literal_added;
75c660ac 162 unsigned long delta_limit;
427dcb4b
JH
163 int score;
164
60896c7b
JH
165 /* We deal only with regular files. Symlink renames are handled
166 * only when they are exact matches --- in other words, no edits
167 * after renaming.
168 */
169 if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
170 return 0;
171
90bd932c 172 max_size = ((src->size > dst->size) ? src->size : dst->size);
58b103f5 173 base_size = ((src->size < dst->size) ? src->size : dst->size);
90bd932c 174 delta_size = max_size - base_size;
427dcb4b 175
58b103f5
JH
176 /* We would not consider edits that change the file size so
177 * drastically. delta_size must be smaller than
cd1870ed 178 * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
f0c6b2a2 179 *
58b103f5
JH
180 * Note that base_size == 0 case is handled here already
181 * and the final score computation below would not have a
182 * divide-by-zero issue.
427dcb4b 183 */
cd1870ed 184 if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
427dcb4b
JH
185 return 0;
186
eede7b7d
JK
187 if ((!src->cnt_data && diff_populate_filespec(src, 0))
188 || (!dst->cnt_data && diff_populate_filespec(dst, 0)))
f0c6b2a2
JH
189 return 0; /* error but caught downstream */
190
85976974 191
dc49cd76
SP
192 delta_limit = (unsigned long)
193 (base_size * (MAX_SCORE-minimum_score) / MAX_SCORE);
d8c3d03a 194 if (diffcore_count_changes(src, dst,
c06c7966 195 &src->cnt_data, &dst->cnt_data,
65416758
JH
196 delta_limit,
197 &src_copied, &literal_added))
85976974 198 return 0;
355e76a4 199
1706306a
JH
200 /* How similar are they?
201 * what percentage of material in dst are from source?
427dcb4b 202 */
90bd932c 203 if (!dst->size)
1706306a 204 score = 0; /* should not happen */
cfc0aef1 205 else
dc49cd76 206 score = (int)(src_copied * MAX_SCORE / max_size);
427dcb4b
JH
207 return score;
208}
209
5098bafb 210static void record_rename_pair(int dst_index, int src_index, int score)
427dcb4b 211{
9fb88419 212 struct diff_filespec *src, *dst;
25d5ea41 213 struct diff_filepair *dp;
f7c1512a 214
25d5ea41
JH
215 if (rename_dst[dst_index].pair)
216 die("internal error: dst already matched.");
427dcb4b 217
25d5ea41 218 src = rename_src[src_index].one;
9fb88419 219 src->count++;
427dcb4b 220
25d5ea41 221 dst = rename_dst[dst_index].two;
9fb88419 222 dst->count++;
427dcb4b 223
9fb88419 224 dp = diff_queue(NULL, src, dst);
ef677686 225 dp->renamed_pair = 1;
fc580719
JH
226 if (!strcmp(src->path, dst->path))
227 dp->score = rename_src[src_index].score;
228 else
229 dp->score = score;
6bac10d8 230 dp->source_stays = rename_src[src_index].src_path_left;
25d5ea41 231 rename_dst[dst_index].pair = dp;
427dcb4b
JH
232}
233
234/*
235 * We sort the rename similarity matrix with the score, in descending
15d061b4 236 * order (the most similar first).
427dcb4b
JH
237 */
238static int score_compare(const void *a_, const void *b_)
239{
240 const struct diff_score *a = a_, *b = b_;
cfc0aef1
RS
241
242 if (a->score == b->score)
243 return b->name_score - a->name_score;
244
427dcb4b
JH
245 return b->score - a->score;
246}
247
6bac10d8
JH
248static int compute_stays(struct diff_queue_struct *q,
249 struct diff_filespec *one)
250{
251 int i;
252 for (i = 0; i < q->nr; i++) {
253 struct diff_filepair *p = q->queue[i];
254 if (strcmp(one->path, p->two->path))
255 continue;
256 if (DIFF_PAIR_RENAME(p)) {
257 return 0; /* something else is renamed into this */
258 }
259 }
260 return 1;
261}
262
cb1491b6
LT
263/*
264 * Find exact renames first.
265 *
266 * The first round matches up the up-to-date entries,
267 * and then during the second round we try to match
268 * cache-dirty entries as well.
269 *
270 * Note: the rest of the rename logic depends on this
271 * phase also populating all the filespecs for any
272 * entry that isn't matched up with an exact rename,
273 * see "is_exact_match()".
274 */
275static int find_exact_renames(void)
276{
277 int rename_count = 0;
278 int contents_too;
279
280 for (contents_too = 0; contents_too < 2; contents_too++) {
281 int i;
282
283 for (i = 0; i < rename_dst_nr; i++) {
284 struct diff_filespec *two = rename_dst[i].two;
285 int j;
286
287 if (rename_dst[i].pair)
288 continue; /* dealt with an earlier round */
289 for (j = 0; j < rename_src_nr; j++) {
290 int k;
291 struct diff_filespec *one = rename_src[j].one;
292 if (!is_exact_match(one, two, contents_too))
293 continue;
294
295 /* see if there is a basename match, too */
296 for (k = j; k < rename_src_nr; k++) {
297 one = rename_src[k].one;
298 if (basename_same(one, two) &&
299 is_exact_match(one, two,
300 contents_too)) {
301 j = k;
302 break;
303 }
304 }
305
306 record_rename_pair(i, j, (int)MAX_SCORE);
307 rename_count++;
308 break; /* we are done with this entry */
309 }
310 }
311 }
312 return rename_count;
313}
314
8082d8d3 315void diffcore_rename(struct diff_options *options)
427dcb4b 316{
8082d8d3
JH
317 int detect_rename = options->detect_rename;
318 int minimum_score = options->rename_score;
319 int rename_limit = options->rename_limit;
38c6f780 320 struct diff_queue_struct *q = &diff_queued_diff;
5098bafb 321 struct diff_queue_struct outq;
427dcb4b 322 struct diff_score *mx;
cb1491b6 323 int i, j, rename_count;
25d5ea41 324 int num_create, num_src, dst_cnt;
427dcb4b 325
26dee0ad 326 if (!minimum_score)
f345b0a0 327 minimum_score = DEFAULT_RENAME_SCORE;
427dcb4b 328
427dcb4b 329 for (i = 0; i < q->nr; i++) {
52e95789 330 struct diff_filepair *p = q->queue[i];
2f3f8b21 331 if (!DIFF_FILE_VALID(p->one)) {
81e50eab 332 if (!DIFF_FILE_VALID(p->two))
60896c7b 333 continue; /* unmerged */
2f3f8b21
JH
334 else if (options->single_follow &&
335 strcmp(options->single_follow, p->two->path))
336 continue; /* not interested */
427dcb4b 337 else
25d5ea41 338 locate_rename_dst(p->two, 1);
2f3f8b21 339 }
2210100a
JH
340 else if (!DIFF_FILE_VALID(p->two)) {
341 /* If the source is a broken "delete", and
342 * they did not really want to get broken,
343 * that means the source actually stays.
344 */
345 int stays = (p->broken_pair && !p->score);
fc580719 346 register_rename_src(p->one, stays, p->score);
2210100a 347 }
15d061b4 348 else if (detect_rename == DIFF_DETECT_COPY)
fc580719 349 register_rename_src(p->one, 1, p->score);
427dcb4b 350 }
0024a549 351 if (rename_dst_nr == 0 || rename_src_nr == 0)
427dcb4b
JH
352 goto cleanup; /* nothing to do */
353
0024a549
LT
354 /*
355 * This basically does a test for the rename matrix not
356 * growing larger than a "rename_limit" square matrix, ie:
357 *
358 * rename_dst_nr * rename_src_nr > rename_limit * rename_limit
359 *
360 * but handles the potential overflow case specially (and we
361 * assume at least 32-bit integers)
362 */
363 if (rename_limit <= 0 || rename_limit > 32767)
364 rename_limit = 32767;
365 if (rename_dst_nr > rename_limit && rename_src_nr > rename_limit)
366 goto cleanup;
367 if (rename_dst_nr * rename_src_nr > rename_limit * rename_limit)
368 goto cleanup;
369
cb1491b6
LT
370 /*
371 * We really want to cull the candidates list early
427dcb4b 372 * with cheap tests in order to avoid doing deltas.
427dcb4b 373 */
cb1491b6 374 rename_count = find_exact_renames();
427dcb4b
JH
375
376 /* Have we run out the created file pool? If so we can avoid
377 * doing the delta matrix altogether.
378 */
5098bafb 379 if (rename_count == rename_dst_nr)
15d061b4 380 goto cleanup;
427dcb4b 381
9f70b806
JH
382 if (minimum_score == MAX_SCORE)
383 goto cleanup;
384
5098bafb 385 num_create = (rename_dst_nr - rename_count);
25d5ea41 386 num_src = rename_src_nr;
427dcb4b 387 mx = xmalloc(sizeof(*mx) * num_create * num_src);
25d5ea41 388 for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
427dcb4b 389 int base = dst_cnt * num_src;
25d5ea41
JH
390 struct diff_filespec *two = rename_dst[i].two;
391 if (rename_dst[i].pair)
427dcb4b 392 continue; /* dealt with exact match already. */
25d5ea41
JH
393 for (j = 0; j < rename_src_nr; j++) {
394 struct diff_filespec *one = rename_src[j].one;
395 struct diff_score *m = &mx[base+j];
396 m->src = j;
397 m->dst = i;
398 m->score = estimate_similarity(one, two,
399 minimum_score);
cfc0aef1 400 m->name_score = basename_same(one, two);
8ae92e63 401 diff_free_filespec_blob(one);
427dcb4b 402 }
2821104d 403 /* We do not need the text anymore */
8ae92e63 404 diff_free_filespec_blob(two);
427dcb4b
JH
405 dst_cnt++;
406 }
407 /* cost matrix sorted by most to least similar pair */
408 qsort(mx, num_create * num_src, sizeof(*mx), score_compare);
409 for (i = 0; i < num_create * num_src; i++) {
25d5ea41
JH
410 struct diff_rename_dst *dst = &rename_dst[mx[i].dst];
411 if (dst->pair)
412 continue; /* already done, either exact or fuzzy. */
427dcb4b 413 if (mx[i].score < minimum_score)
15d061b4 414 break; /* there is no more usable pair. */
5098bafb
JH
415 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
416 rename_count++;
427dcb4b
JH
417 }
418 free(mx);
427dcb4b 419
15d061b4 420 cleanup:
427dcb4b 421 /* At this point, we have found some renames and copies and they
5098bafb 422 * are recorded in rename_dst. The original list is still in *q.
427dcb4b 423 */
25d5ea41
JH
424 outq.queue = NULL;
425 outq.nr = outq.alloc = 0;
427dcb4b 426 for (i = 0; i < q->nr; i++) {
25d5ea41 427 struct diff_filepair *p = q->queue[i];
25d5ea41
JH
428 struct diff_filepair *pair_to_free = NULL;
429
2cd68882
JH
430 if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
431 /*
432 * Creation
433 *
434 * We would output this create record if it has
435 * not been turned into a rename/copy already.
436 */
437 struct diff_rename_dst *dst =
438 locate_rename_dst(p->two, 0);
439 if (dst && dst->pair) {
25d5ea41
JH
440 diff_q(&outq, dst->pair);
441 pair_to_free = p;
442 }
443 else
2cd68882
JH
444 /* no matching rename/copy source, so
445 * record this as a creation.
25d5ea41
JH
446 */
447 diff_q(&outq, p);
427dcb4b 448 }
2cd68882
JH
449 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
450 /*
451 * Deletion
452 *
f345b0a0
JH
453 * We would output this delete record if:
454 *
455 * (1) this is a broken delete and the counterpart
456 * broken create remains in the output; or
5098bafb
JH
457 * (2) this is not a broken delete, and rename_dst
458 * does not have a rename/copy to move p->one->path
459 * out of existence.
f345b0a0
JH
460 *
461 * Otherwise, the counterpart broken create
462 * has been turned into a rename-edit; or
463 * delete did not have a matching create to
464 * begin with.
2cd68882 465 */
f345b0a0
JH
466 if (DIFF_PAIR_BROKEN(p)) {
467 /* broken delete */
468 struct diff_rename_dst *dst =
469 locate_rename_dst(p->one, 0);
470 if (dst && dst->pair)
471 /* counterpart is now rename/copy */
472 pair_to_free = p;
473 }
474 else {
5098bafb
JH
475 for (j = 0; j < rename_dst_nr; j++) {
476 if (!rename_dst[j].pair)
477 continue;
478 if (strcmp(rename_dst[j].pair->
479 one->path,
480 p->one->path))
481 continue;
482 break;
483 }
484 if (j < rename_dst_nr)
f345b0a0
JH
485 /* this path remains */
486 pair_to_free = p;
487 }
2cd68882
JH
488
489 if (pair_to_free)
490 ;
491 else
492 diff_q(&outq, p);
493 }
25d5ea41 494 else if (!diff_unmodified_pair(p))
15d061b4 495 /* all the usual ones need to be kept */
25d5ea41 496 diff_q(&outq, p);
15d061b4
JH
497 else
498 /* no need to keep unmodified pairs */
499 pair_to_free = p;
500
226406f6
JH
501 if (pair_to_free)
502 diff_free_filepair(pair_to_free);
427dcb4b 503 }
25d5ea41 504 diff_debug_queue("done copying original", &outq);
427dcb4b 505
25d5ea41
JH
506 free(q->queue);
507 *q = outq;
508 diff_debug_queue("done collapsing", q);
427dcb4b 509
6bac10d8
JH
510 /* We need to see which rename source really stays here;
511 * earlier we only checked if the path is left in the result,
512 * but even if a path remains in the result, if that is coming
513 * from copying something else on top of it, then the original
514 * source is lost and does not stay.
515 */
516 for (i = 0; i < q->nr; i++) {
517 struct diff_filepair *p = q->queue[i];
518 if (DIFF_PAIR_RENAME(p) && p->source_stays) {
519 /* If one appears as the target of a rename-copy,
520 * then mark p->source_stays = 0; otherwise
521 * leave it as is.
522 */
523 p->source_stays = compute_stays(q, p->one);
524 }
525 }
526
9fb88419
LT
527 for (i = 0; i < rename_dst_nr; i++)
528 free_filespec(rename_dst[i].two);
5098bafb 529
25d5ea41
JH
530 free(rename_dst);
531 rename_dst = NULL;
532 rename_dst_nr = rename_dst_alloc = 0;
533 free(rename_src);
534 rename_src = NULL;
535 rename_src_nr = rename_src_alloc = 0;
427dcb4b
JH
536 return;
537}