1/* 2 * Copyright (C) 2005 Junio C Hamano 3 */ 4#include "cache.h" 5#include "diff.h" 6#include "diffcore.h" 7#include "delta.h" 8#include "count-delta.h" 9 10/* Table of rename/copy destinations */ 11 12static struct diff_rename_dst { 13 struct diff_filespec *two; 14 struct diff_filepair *pair; 15} *rename_dst; 16static int rename_dst_nr, rename_dst_alloc; 17 18static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two, 19 int insert_ok) 20{ 21 int first, last; 22 23 first = 0; 24 last = rename_dst_nr; 25 while (last > first) { 26 int next = (last + first) >> 1; 27 struct diff_rename_dst *dst = &(rename_dst[next]); 28 int cmp = strcmp(two->path, dst->two->path); 29 if (!cmp) 30 return dst; 31 if (cmp < 0) { 32 last = next; 33 continue; 34 } 35 first = next+1; 36 } 37 /* not found */ 38 if (!insert_ok) 39 return NULL; 40 /* insert to make it at "first" */ 41 if (rename_dst_alloc <= rename_dst_nr) { 42 rename_dst_alloc = alloc_nr(rename_dst_alloc); 43 rename_dst = xrealloc(rename_dst, 44 rename_dst_alloc * sizeof(*rename_dst)); 45 } 46 rename_dst_nr++; 47 if (first < rename_dst_nr) 48 memmove(rename_dst + first + 1, rename_dst + first, 49 (rename_dst_nr - first - 1) * sizeof(*rename_dst)); 50 rename_dst[first].two = two; 51 rename_dst[first].pair = NULL; 52 return &(rename_dst[first]); 53} 54 55static struct diff_rename_src { 56 struct diff_filespec *one; 57 unsigned src_used : 1; 58} *rename_src; 59static int rename_src_nr, rename_src_alloc; 60 61static struct diff_rename_src *locate_rename_src(struct diff_filespec *one, 62 int insert_ok) 63{ 64 int first, last; 65 66 first = 0; 67 last = rename_src_nr; 68 while (last > first) { 69 int next = (last + first) >> 1; 70 struct diff_rename_src *src = &(rename_src[next]); 71 int cmp = strcmp(one->path, src->one->path); 72 if (!cmp) 73 return src; 74 if (cmp < 0) { 75 last = next; 76 continue; 77 } 78 first = next+1; 79 } 80 /* not found */ 81 if (!insert_ok) 82 return NULL; 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)); 88 } 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; 94 rename_src[first].src_used = 0; 95 return &(rename_src[first]); 96} 97 98static int is_exact_match(struct diff_filespec *src, struct diff_filespec *dst) 99{ 100 if (src->sha1_valid && dst->sha1_valid && 101 !memcmp(src->sha1, dst->sha1, 20)) 102 return 1; 103 if (diff_populate_filespec(src) || diff_populate_filespec(dst)) 104 /* this is an error but will be caught downstream */ 105 return 0; 106 if (src->size == dst->size && 107 !memcmp(src->data, dst->data, src->size)) 108 return 1; 109 return 0; 110} 111 112struct diff_score { 113 int src; /* index in rename_src */ 114 int dst; /* index in rename_dst */ 115 int score; 116}; 117 118static int estimate_similarity(struct diff_filespec *src, 119 struct diff_filespec *dst, 120 int minimum_score) 121{ 122 /* src points at a file that existed in the original tree (or 123 * optionally a file in the destination tree) and dst points 124 * at a newly created file. They may be quite similar, in which 125 * case we want to say src is renamed to dst or src is copied into 126 * dst, and then some edit has been applied to dst. 127 * 128 * Compare them and return how similar they are, representing 129 * the score as an integer between 0 and 10000, except 130 * where they match exactly it is considered better than anything 131 * else. 132 */ 133 void *delta; 134 unsigned long delta_size, base_size; 135 int score; 136 137 /* We deal only with regular files. Symlink renames are handled 138 * only when they are exact matches --- in other words, no edits 139 * after renaming. 140 */ 141 if (!S_ISREG(src->mode) || !S_ISREG(dst->mode)) 142 return 0; 143 144 delta_size = ((src->size < dst->size) ? 145 (dst->size - src->size) : (src->size - dst->size)); 146 base_size = ((src->size < dst->size) ? src->size : dst->size); 147 148 /* We would not consider edits that change the file size so 149 * drastically. delta_size must be smaller than 150 * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size). 151 * Note that base_size == 0 case is handled here already 152 * and the final score computation below would not have a 153 * divide-by-zero issue. 154 */ 155 if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE) 156 return 0; 157 158 delta = diff_delta(src->data, src->size, 159 dst->data, dst->size, 160 &delta_size); 161 162 /* A delta that has a lot of literal additions would have 163 * big delta_size no matter what else it does. 164 */ 165 if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE) 166 return 0; 167 168 /* Estimate the edit size by interpreting delta. */ 169 delta_size = count_delta(delta, delta_size); 170 free(delta); 171 if (delta_size == UINT_MAX) 172 return 0; 173 174 /* 175 * Now we will give some score to it. 100% edit gets 0 points 176 * and 0% edit gets MAX_SCORE points. 177 */ 178 score = MAX_SCORE - (MAX_SCORE * delta_size / base_size); 179 if (score < 0) return 0; 180 if (MAX_SCORE < score) return MAX_SCORE; 181 return score; 182} 183 184static void record_rename_pair(struct diff_queue_struct *renq, 185 int dst_index, int src_index, int score) 186{ 187 struct diff_filespec *one, *two, *src, *dst; 188 struct diff_filepair *dp; 189 190 if (rename_dst[dst_index].pair) 191 die("internal error: dst already matched."); 192 193 src = rename_src[src_index].one; 194 one = alloc_filespec(src->path); 195 fill_filespec(one, src->sha1, src->mode); 196 197 dst = rename_dst[dst_index].two; 198 two = alloc_filespec(dst->path); 199 fill_filespec(two, dst->sha1, dst->mode); 200 201 dp = diff_queue(renq, one, two); 202 dp->score = score; 203 204 rename_src[src_index].src_used = 1; 205 rename_dst[dst_index].pair = dp; 206} 207 208/* 209 * We sort the rename similarity matrix with the score, in descending 210 * order (more similar first). 211 */ 212static int score_compare(const void *a_, const void *b_) 213{ 214 const struct diff_score *a = a_, *b = b_; 215 return b->score - a->score; 216} 217 218int diff_scoreopt_parse(const char *opt) 219{ 220 int diglen, num, scale, i; 221 if (opt[0] != '-' || (opt[1] != 'M' && opt[1] != 'C')) 222 return -1; /* that is not a -M nor -C option */ 223 diglen = strspn(opt+2, "0123456789"); 224 if (diglen == 0 || strlen(opt+2) != diglen) 225 return 0; /* use default */ 226 sscanf(opt+2, "%d", &num); 227 for (i = 0, scale = 1; i < diglen; i++) 228 scale *= 10; 229 230 /* user says num divided by scale and we say internally that 231 * is MAX_SCORE * num / scale. 232 */ 233 return MAX_SCORE * num / scale; 234} 235 236void diffcore_rename(int detect_rename, int minimum_score) 237{ 238 struct diff_queue_struct *q = &diff_queued_diff; 239 struct diff_queue_struct renq, outq; 240 struct diff_score *mx; 241 int i, j; 242 int num_create, num_src, dst_cnt; 243 244 if (!minimum_score) 245 minimum_score = DEFAULT_MINIMUM_SCORE; 246 renq.queue = NULL; 247 renq.nr = renq.alloc = 0; 248 249 for (i = 0; i < q->nr; i++) { 250 struct diff_filepair *p = q->queue[i]; 251 if (!DIFF_FILE_VALID(p->one)) 252 if (!DIFF_FILE_VALID(p->two)) 253 continue; /* unmerged */ 254 else 255 locate_rename_dst(p->two, 1); 256 else if (!DIFF_FILE_VALID(p->two)) 257 locate_rename_src(p->one, 1); 258 else if (1 < detect_rename) /* find copy, too */ 259 locate_rename_src(p->one, 1); 260 } 261 if (rename_dst_nr == 0) 262 goto cleanup; /* nothing to do */ 263 264 /* We really want to cull the candidates list early 265 * with cheap tests in order to avoid doing deltas. 266 */ 267 for (i = 0; i < rename_dst_nr; i++) { 268 struct diff_filespec *two = rename_dst[i].two; 269 for (j = 0; j < rename_src_nr; j++) { 270 struct diff_filespec *one = rename_src[j].one; 271 if (!is_exact_match(one, two)) 272 continue; 273 record_rename_pair(&renq, i, j, MAX_SCORE); 274 break; /* we are done with this entry */ 275 } 276 } 277 diff_debug_queue("done detecting exact", &renq); 278 279 /* Have we run out the created file pool? If so we can avoid 280 * doing the delta matrix altogether. 281 */ 282 if (renq.nr == rename_dst_nr) 283 goto flush_rest; 284 285 num_create = (rename_dst_nr - renq.nr); 286 num_src = rename_src_nr; 287 mx = xmalloc(sizeof(*mx) * num_create * num_src); 288 for (dst_cnt = i = 0; i < rename_dst_nr; i++) { 289 int base = dst_cnt * num_src; 290 struct diff_filespec *two = rename_dst[i].two; 291 if (rename_dst[i].pair) 292 continue; /* dealt with exact match already. */ 293 for (j = 0; j < rename_src_nr; j++) { 294 struct diff_filespec *one = rename_src[j].one; 295 struct diff_score *m = &mx[base+j]; 296 m->src = j; 297 m->dst = i; 298 m->score = estimate_similarity(one, two, 299 minimum_score); 300 } 301 dst_cnt++; 302 } 303 /* cost matrix sorted by most to least similar pair */ 304 qsort(mx, num_create * num_src, sizeof(*mx), score_compare); 305 for (i = 0; i < num_create * num_src; i++) { 306 struct diff_rename_dst *dst = &rename_dst[mx[i].dst]; 307 if (dst->pair) 308 continue; /* already done, either exact or fuzzy. */ 309 if (mx[i].score < minimum_score) 310 break; /* there is not any more diffs applicable. */ 311 record_rename_pair(&renq, mx[i].dst, mx[i].src, mx[i].score); 312 } 313 free(mx); 314 diff_debug_queue("done detecting fuzzy", &renq); 315 316 flush_rest: 317 /* At this point, we have found some renames and copies and they 318 * are kept in renq. The original list is still in *q. 319 * 320 * Scan the original list and move them into the outq; we will sort 321 * outq and swap it into the queue supplied to pass that to 322 * downstream, so we assign the sort keys in this loop. 323 * 324 * See comments at the top of record_rename_pair for numbers used 325 * to assign rename_rank. 326 */ 327 outq.queue = NULL; 328 outq.nr = outq.alloc = 0; 329 for (i = 0; i < q->nr; i++) { 330 struct diff_filepair *p = q->queue[i]; 331 struct diff_rename_src *src = locate_rename_src(p->one, 0); 332 struct diff_rename_dst *dst = locate_rename_dst(p->two, 0); 333 struct diff_filepair *pair_to_free = NULL; 334 335 if (dst) { 336 /* creation */ 337 if (dst->pair) { 338 /* renq has rename/copy already to produce 339 * this file, so we do not emit the creation 340 * record in the output. 341 */ 342 diff_q(&outq, dst->pair); 343 pair_to_free = p; 344 } 345 else 346 /* no matching rename/copy source, so record 347 * this as a creation. 348 */ 349 diff_q(&outq, p); 350 } 351 else if (!diff_unmodified_pair(p)) 352 /* all the other cases need to be recorded as is */ 353 diff_q(&outq, p); 354 else { 355 /* unmodified pair needs to be recorded only if 356 * it is used as the source of rename/copy 357 */ 358 if (src && src->src_used) 359 diff_q(&outq, p); 360 else 361 pair_to_free = p; 362 } 363 if (pair_to_free) 364 diff_free_filepair(pair_to_free); 365 } 366 diff_debug_queue("done copying original", &outq); 367 368 free(renq.queue); 369 free(q->queue); 370 *q = outq; 371 diff_debug_queue("done collapsing", q); 372 373 cleanup: 374 free(rename_dst); 375 rename_dst = NULL; 376 rename_dst_nr = rename_dst_alloc = 0; 377 free(rename_src); 378 rename_src = NULL; 379 rename_src_nr = rename_src_alloc = 0; 380 return; 381}