diffcore-rename.c

   1 /*
   2  * Copyright (C) 2005 Junio C Hamano
   3  */
   4 #include "cache.h"
   5 #include "diff.h"
   6 #include "diffcore.h"
   7 #include "hashmap.h"
   8 #include "progress.h"
   9
  10 /* Table of rename/copy destinations */
  11
  12 static struct diff_rename_dst {
  13         struct diff_filespec *two;
  14         struct diff_filepair *pair;
  15 } *rename_dst;
  16 static int rename_dst_nr, rename_dst_alloc;
  17
  18 static 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         ALLOC_GROW(rename_dst, rename_dst_nr + 1, rename_dst_alloc);
  42         rename_dst_nr++;
  43         if (first < rename_dst_nr)
  44                 memmove(rename_dst + first + 1, rename_dst + first,
  45                         (rename_dst_nr - first - 1) * sizeof(*rename_dst));
  46         rename_dst[first].two = alloc_filespec(two->path);
  47         fill_filespec(rename_dst[first].two, two->sha1, two->sha1_valid, two->mode);
  48         rename_dst[first].pair = NULL;
  49         return &(rename_dst[first]);
  50 }
  51
  52 /* Table of rename/copy src files */
  53 static struct diff_rename_src {
  54         struct diff_filepair *p;
  55         unsigned short score; /* to remember the break score */
  56 } *rename_src;
  57 static int rename_src_nr, rename_src_alloc;
  58
  59 static struct diff_rename_src *register_rename_src(struct diff_filepair *p)
  60 {
  61         int first, last;
  62         struct diff_filespec *one = p->one;
  63         unsigned short score = p->score;
  64
  65         first = 0;
  66         last = rename_src_nr;
  67         while (last > first) {
  68                 int next = (last + first) >> 1;
  69                 struct diff_rename_src *src = &(rename_src[next]);
  70                 int cmp = strcmp(one->path, src->p->one->path);
  71                 if (!cmp)
  72                         return src;
  73                 if (cmp < 0) {
  74                         last = next;
  75                         continue;
  76                 }
  77                 first = next+1;
  78         }
  79
  80         /* insert to make it at "first" */
  81         ALLOC_GROW(rename_src, rename_src_nr + 1, rename_src_alloc);
  82         rename_src_nr++;
  83         if (first < rename_src_nr)
  84                 memmove(rename_src + first + 1, rename_src + first,
  85                         (rename_src_nr - first - 1) * sizeof(*rename_src));
  86         rename_src[first].p = p;
  87         rename_src[first].score = score;
  88         return &(rename_src[first]);
  89 }
  90
  91 static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
  92 {
  93         int src_len = strlen(src->path), dst_len = strlen(dst->path);
  94         while (src_len && dst_len) {
  95                 char c1 = src->path[--src_len];
  96                 char c2 = dst->path[--dst_len];
  97                 if (c1 != c2)
  98                         return 0;
  99                 if (c1 == '/')
 100                         return 1;
 101         }
 102         return (!src_len || src->path[src_len - 1] == '/') &&
 103                 (!dst_len || dst->path[dst_len - 1] == '/');
 104 }
 105
 106 struct diff_score {
 107         int src; /* index in rename_src */
 108         int dst; /* index in rename_dst */
 109         unsigned short score;
 110         short name_score;
 111 };
 112
 113 static int estimate_similarity(struct diff_filespec *src,
 114                                struct diff_filespec *dst,
 115                                int minimum_score)
 116 {
 117         /* src points at a file that existed in the original tree (or
 118          * optionally a file in the destination tree) and dst points
 119          * at a newly created file.  They may be quite similar, in which
 120          * case we want to say src is renamed to dst or src is copied into
 121          * dst, and then some edit has been applied to dst.
 122          *
 123          * Compare them and return how similar they are, representing
 124          * the score as an integer between 0 and MAX_SCORE.
 125          *
 126          * When there is an exact match, it is considered a better
 127          * match than anything else; the destination does not even
 128          * call into this function in that case.
 129          */
 130         unsigned long max_size, delta_size, base_size, src_copied, literal_added;
 131         unsigned long delta_limit;
 132         int score;
 133
 134         /* We deal only with regular files.  Symlink renames are handled
 135          * only when they are exact matches --- in other words, no edits
 136          * after renaming.
 137          */
 138         if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
 139                 return 0;
 140
 141         /*
 142          * Need to check that source and destination sizes are
 143          * filled in before comparing them.
 144          *
 145          * If we already have "cnt_data" filled in, we know it's
 146          * all good (avoid checking the size for zero, as that
 147          * is a possible size - we really should have a flag to
 148          * say whether the size is valid or not!)
 149          */
 150         if (!src->cnt_data && diff_populate_filespec(src, 1))
 151                 return 0;
 152         if (!dst->cnt_data && diff_populate_filespec(dst, 1))
 153                 return 0;
 154
 155         max_size = ((src->size > dst->size) ? src->size : dst->size);
 156         base_size = ((src->size < dst->size) ? src->size : dst->size);
 157         delta_size = max_size - base_size;
 158
 159         /* We would not consider edits that change the file size so
 160          * drastically.  delta_size must be smaller than
 161          * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
 162          *
 163          * Note that base_size == 0 case is handled here already
 164          * and the final score computation below would not have a
 165          * divide-by-zero issue.
 166          */
 167         if (max_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
 168                 return 0;
 169
 170         if (!src->cnt_data && diff_populate_filespec(src, 0))
 171                 return 0;
 172         if (!dst->cnt_data && diff_populate_filespec(dst, 0))
 173                 return 0;
 174
 175         delta_limit = (unsigned long)
 176                 (base_size * (MAX_SCORE-minimum_score) / MAX_SCORE);
 177         if (diffcore_count_changes(src, dst,
 178                                    &src->cnt_data, &dst->cnt_data,
 179                                    delta_limit,
 180                                    &src_copied, &literal_added))
 181                 return 0;
 182
 183         /* How similar are they?
 184          * what percentage of material in dst are from source?
 185          */
 186         if (!dst->size)
 187                 score = 0; /* should not happen */
 188         else
 189                 score = (int)(src_copied * MAX_SCORE / max_size);
 190         return score;
 191 }
 192
 193 static void record_rename_pair(int dst_index, int src_index, int score)
 194 {
 195         struct diff_filespec *src, *dst;
 196         struct diff_filepair *dp;
 197
 198         if (rename_dst[dst_index].pair)
 199                 die("internal error: dst already matched.");
 200
 201         src = rename_src[src_index].p->one;
 202         src->rename_used++;
 203         src->count++;
 204
 205         dst = rename_dst[dst_index].two;
 206         dst->count++;
 207
 208         dp = diff_queue(NULL, src, dst);
 209         dp->renamed_pair = 1;
 210         if (!strcmp(src->path, dst->path))
 211                 dp->score = rename_src[src_index].score;
 212         else
 213                 dp->score = score;
 214         rename_dst[dst_index].pair = dp;
 215 }
 216
 217 /*
 218  * We sort the rename similarity matrix with the score, in descending
 219  * order (the most similar first).
 220  */
 221 static int score_compare(const void *a_, const void *b_)
 222 {
 223         const struct diff_score *a = a_, *b = b_;
 224
 225         /* sink the unused ones to the bottom */
 226         if (a->dst < 0)
 227                 return (0 <= b->dst);
 228         else if (b->dst < 0)
 229                 return -1;
 230
 231         if (a->score == b->score)
 232                 return b->name_score - a->name_score;
 233
 234         return b->score - a->score;
 235 }
 236
 237 struct file_similarity {
 238         struct hashmap_entry entry;
 239         int index;
 240         struct diff_filespec *filespec;
 241 };
 242
 243 static unsigned int hash_filespec(struct diff_filespec *filespec)
 244 {
 245         if (!filespec->sha1_valid) {
 246                 if (diff_populate_filespec(filespec, 0))
 247                         return 0;
 248                 hash_sha1_file(filespec->data, filespec->size, "blob", filespec->sha1);
 249         }
 250         return sha1hash(filespec->sha1);
 251 }
 252
 253 static int find_identical_files(struct hashmap *srcs,
 254                                 int dst_index,
 255                                 struct diff_options *options)
 256 {
 257         int renames = 0;
 258
 259         struct diff_filespec *target = rename_dst[dst_index].two;
 260         struct file_similarity *p, *best = NULL;
 261         int i = 100, best_score = -1;
 262
 263         /*
 264          * Find the best source match for specified destination.
 265          */
 266         p = hashmap_get_from_hash(srcs, hash_filespec(target), NULL);
 267         for (; p; p = hashmap_get_next(srcs, p)) {
 268                 int score;
 269                 struct diff_filespec *source = p->filespec;
 270
 271                 /* False hash collision? */
 272                 if (hashcmp(source->sha1, target->sha1))
 273                         continue;
 274                 /* Non-regular files? If so, the modes must match! */
 275                 if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
 276                         if (source->mode != target->mode)
 277                                 continue;
 278                 }
 279                 /* Give higher scores to sources that haven't been used already */
 280                 score = !source->rename_used;
 281                 if (source->rename_used && options->detect_rename != DIFF_DETECT_COPY)
 282                         continue;
 283                 score += basename_same(source, target);
 284                 if (score > best_score) {
 285                         best = p;
 286                         best_score = score;
 287                         if (score == 2)
 288                                 break;
 289                 }
 290
 291                 /* Too many identical alternatives? Pick one */
 292                 if (!--i)
 293                         break;
 294         }
 295         if (best) {
 296                 record_rename_pair(dst_index, best->index, MAX_SCORE);
 297                 renames++;
 298         }
 299         return renames;
 300 }
 301
 302 static void insert_file_table(struct hashmap *table, int index, struct diff_filespec *filespec)
 303 {
 304         struct file_similarity *entry = xmalloc(sizeof(*entry));
 305
 306         entry->index = index;
 307         entry->filespec = filespec;
 308
 309         hashmap_entry_init(entry, hash_filespec(filespec));
 310         hashmap_add(table, entry);
 311 }
 312
 313 /*
 314  * Find exact renames first.
 315  *
 316  * The first round matches up the up-to-date entries,
 317  * and then during the second round we try to match
 318  * cache-dirty entries as well.
 319  */
 320 static int find_exact_renames(struct diff_options *options)
 321 {
 322         int i, renames = 0;
 323         struct hashmap file_table;
 324
 325         /* Add all sources to the hash table */
 326         hashmap_init(&file_table, NULL, rename_src_nr);
 327         for (i = 0; i < rename_src_nr; i++)
 328                 insert_file_table(&file_table, i, rename_src[i].p->one);
 329
 330         /* Walk the destinations and find best source match */
 331         for (i = 0; i < rename_dst_nr; i++)
 332                 renames += find_identical_files(&file_table, i, options);
 333
 334         /* Free the hash data structure and entries */
 335         hashmap_free(&file_table, 1);
 336
 337         return renames;
 338 }
 339
 340 #define NUM_CANDIDATE_PER_DST 4
 341 static void record_if_better(struct diff_score m[], struct diff_score *o)
 342 {
 343         int i, worst;
 344
 345         /* find the worst one */
 346         worst = 0;
 347         for (i = 1; i < NUM_CANDIDATE_PER_DST; i++)
 348                 if (score_compare(&m[i], &m[worst]) > 0)
 349                         worst = i;
 350
 351         /* is it better than the worst one? */
 352         if (score_compare(&m[worst], o) > 0)
 353                 m[worst] = *o;
 354 }
 355
 356 /*
 357  * Returns:
 358  * 0 if we are under the limit;
 359  * 1 if we need to disable inexact rename detection;
 360  * 2 if we would be under the limit if we were given -C instead of -C -C.
 361  */
 362 static int too_many_rename_candidates(int num_create,
 363                                       struct diff_options *options)
 364 {
 365         int rename_limit = options->rename_limit;
 366         int num_src = rename_src_nr;
 367         int i;
 368
 369         options->needed_rename_limit = 0;
 370
 371         /*
 372          * This basically does a test for the rename matrix not
 373          * growing larger than a "rename_limit" square matrix, ie:
 374          *
 375          *    num_create * num_src > rename_limit * rename_limit
 376          *
 377          * but handles the potential overflow case specially (and we
 378          * assume at least 32-bit integers)
 379          */
 380         if (rename_limit <= 0 || rename_limit > 32767)
 381                 rename_limit = 32767;
 382         if ((num_create <= rename_limit || num_src <= rename_limit) &&
 383             (num_create * num_src <= rename_limit * rename_limit))
 384                 return 0;
 385
 386         options->needed_rename_limit =
 387                 num_src > num_create ? num_src : num_create;
 388
 389         /* Are we running under -C -C? */
 390         if (!DIFF_OPT_TST(options, FIND_COPIES_HARDER))
 391                 return 1;
 392
 393         /* Would we bust the limit if we were running under -C? */
 394         for (num_src = i = 0; i < rename_src_nr; i++) {
 395                 if (diff_unmodified_pair(rename_src[i].p))
 396                         continue;
 397                 num_src++;
 398         }
 399         if ((num_create <= rename_limit || num_src <= rename_limit) &&
 400             (num_create * num_src <= rename_limit * rename_limit))
 401                 return 2;
 402         return 1;
 403 }
 404
 405 static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, int copies)
 406 {
 407         int count = 0, i;
 408
 409         for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
 410                 struct diff_rename_dst *dst;
 411
 412                 if ((mx[i].dst < 0) ||
 413                     (mx[i].score < minimum_score))
 414                         break; /* there is no more usable pair. */
 415                 dst = &rename_dst[mx[i].dst];
 416                 if (dst->pair)
 417                         continue; /* already done, either exact or fuzzy. */
 418                 if (!copies && rename_src[mx[i].src].p->one->rename_used)
 419                         continue;
 420                 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
 421                 count++;
 422         }
 423         return count;
 424 }
 425
 426 void diffcore_rename(struct diff_options *options)
 427 {
 428         int detect_rename = options->detect_rename;
 429         int minimum_score = options->rename_score;
 430         struct diff_queue_struct *q = &diff_queued_diff;
 431         struct diff_queue_struct outq;
 432         struct diff_score *mx;
 433         int i, j, rename_count, skip_unmodified = 0;
 434         int num_create, dst_cnt;
 435         struct progress *progress = NULL;
 436
 437         if (!minimum_score)
 438                 minimum_score = DEFAULT_RENAME_SCORE;
 439
 440         for (i = 0; i < q->nr; i++) {
 441                 struct diff_filepair *p = q->queue[i];
 442                 if (!DIFF_FILE_VALID(p->one)) {
 443                         if (!DIFF_FILE_VALID(p->two))
 444                                 continue; /* unmerged */
 445                         else if (options->single_follow &&
 446                                  strcmp(options->single_follow, p->two->path))
 447                                 continue; /* not interested */
 448                         else if (!DIFF_OPT_TST(options, RENAME_EMPTY) &&
 449                                  is_empty_blob_sha1(p->two->sha1))
 450                                 continue;
 451                         else
 452                                 locate_rename_dst(p->two, 1);
 453                 }
 454                 else if (!DIFF_OPT_TST(options, RENAME_EMPTY) &&
 455                          is_empty_blob_sha1(p->one->sha1))
 456                         continue;
 457                 else if (!DIFF_PAIR_UNMERGED(p) && !DIFF_FILE_VALID(p->two)) {
 458                         /*
 459                          * If the source is a broken "delete", and
 460                          * they did not really want to get broken,
 461                          * that means the source actually stays.
 462                          * So we increment the "rename_used" score
 463                          * by one, to indicate ourselves as a user
 464                          */
 465                         if (p->broken_pair && !p->score)
 466                                 p->one->rename_used++;
 467                         register_rename_src(p);
 468                 }
 469                 else if (detect_rename == DIFF_DETECT_COPY) {
 470                         /*
 471                          * Increment the "rename_used" score by
 472                          * one, to indicate ourselves as a user.
 473                          */
 474                         p->one->rename_used++;
 475                         register_rename_src(p);
 476                 }
 477         }
 478         if (rename_dst_nr == 0 || rename_src_nr == 0)
 479                 goto cleanup; /* nothing to do */
 480
 481         /*
 482          * We really want to cull the candidates list early
 483          * with cheap tests in order to avoid doing deltas.
 484          */
 485         rename_count = find_exact_renames(options);
 486
 487         /* Did we only want exact renames? */
 488         if (minimum_score == MAX_SCORE)
 489                 goto cleanup;
 490
 491         /*
 492          * Calculate how many renames are left (but all the source
 493          * files still remain as options for rename/copies!)
 494          */
 495         num_create = (rename_dst_nr - rename_count);
 496
 497         /* All done? */
 498         if (!num_create)
 499                 goto cleanup;
 500
 501         switch (too_many_rename_candidates(num_create, options)) {
 502         case 1:
 503                 goto cleanup;
 504         case 2:
 505                 options->degraded_cc_to_c = 1;
 506                 skip_unmodified = 1;
 507                 break;
 508         default:
 509                 break;
 510         }
 511
 512         if (options->show_rename_progress) {
 513                 progress = start_progress_delay(
 514                                 _("Performing inexact rename detection"),
 515                                 rename_dst_nr * rename_src_nr, 50, 1);
 516         }
 517
 518         mx = xcalloc(num_create * NUM_CANDIDATE_PER_DST, sizeof(*mx));
 519         for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
 520                 struct diff_filespec *two = rename_dst[i].two;
 521                 struct diff_score *m;
 522
 523                 if (rename_dst[i].pair)
 524                         continue; /* dealt with exact match already. */
 525
 526                 m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST];
 527                 for (j = 0; j < NUM_CANDIDATE_PER_DST; j++)
 528                         m[j].dst = -1;
 529
 530                 for (j = 0; j < rename_src_nr; j++) {
 531                         struct diff_filespec *one = rename_src[j].p->one;
 532                         struct diff_score this_src;
 533
 534                         if (skip_unmodified &&
 535                             diff_unmodified_pair(rename_src[j].p))
 536                                 continue;
 537
 538                         this_src.score = estimate_similarity(one, two,
 539                                                              minimum_score);
 540                         this_src.name_score = basename_same(one, two);
 541                         this_src.dst = i;
 542                         this_src.src = j;
 543                         record_if_better(m, &this_src);
 544                         /*
 545                          * Once we run estimate_similarity,
 546                          * We do not need the text anymore.
 547                          */
 548                         diff_free_filespec_blob(one);
 549                         diff_free_filespec_blob(two);
 550                 }
 551                 dst_cnt++;
 552                 display_progress(progress, (i+1)*rename_src_nr);
 553         }
 554         stop_progress(&progress);
 555
 556         /* cost matrix sorted by most to least similar pair */
 557         qsort(mx, dst_cnt * NUM_CANDIDATE_PER_DST, sizeof(*mx), score_compare);
 558
 559         rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
 560         if (detect_rename == DIFF_DETECT_COPY)
 561                 rename_count += find_renames(mx, dst_cnt, minimum_score, 1);
 562         free(mx);
 563
 564  cleanup:
 565         /* At this point, we have found some renames and copies and they
 566          * are recorded in rename_dst.  The original list is still in *q.
 567          */
 568         DIFF_QUEUE_CLEAR(&outq);
 569         for (i = 0; i < q->nr; i++) {
 570                 struct diff_filepair *p = q->queue[i];
 571                 struct diff_filepair *pair_to_free = NULL;
 572
 573                 if (DIFF_PAIR_UNMERGED(p)) {
 574                         diff_q(&outq, p);
 575                 }
 576                 else if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
 577                         /*
 578                          * Creation
 579                          *
 580                          * We would output this create record if it has
 581                          * not been turned into a rename/copy already.
 582                          */
 583                         struct diff_rename_dst *dst =
 584                                 locate_rename_dst(p->two, 0);
 585                         if (dst && dst->pair) {
 586                                 diff_q(&outq, dst->pair);
 587                                 pair_to_free = p;
 588                         }
 589                         else
 590                                 /* no matching rename/copy source, so
 591                                  * record this as a creation.
 592                                  */
 593                                 diff_q(&outq, p);
 594                 }
 595                 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
 596                         /*
 597                          * Deletion
 598                          *
 599                          * We would output this delete record if:
 600                          *
 601                          * (1) this is a broken delete and the counterpart
 602                          *     broken create remains in the output; or
 603                          * (2) this is not a broken delete, and rename_dst
 604                          *     does not have a rename/copy to move p->one->path
 605                          *     out of existence.
 606                          *
 607                          * Otherwise, the counterpart broken create
 608                          * has been turned into a rename-edit; or
 609                          * delete did not have a matching create to
 610                          * begin with.
 611                          */
 612                         if (DIFF_PAIR_BROKEN(p)) {
 613                                 /* broken delete */
 614                                 struct diff_rename_dst *dst =
 615                                         locate_rename_dst(p->one, 0);
 616                                 if (dst && dst->pair)
 617                                         /* counterpart is now rename/copy */
 618                                         pair_to_free = p;
 619                         }
 620                         else {
 621                                 if (p->one->rename_used)
 622                                         /* this path remains */
 623                                         pair_to_free = p;
 624                         }
 625
 626                         if (pair_to_free)
 627                                 ;
 628                         else
 629                                 diff_q(&outq, p);
 630                 }
 631                 else if (!diff_unmodified_pair(p))
 632                         /* all the usual ones need to be kept */
 633                         diff_q(&outq, p);
 634                 else
 635                         /* no need to keep unmodified pairs */
 636                         pair_to_free = p;
 637
 638                 if (pair_to_free)
 639                         diff_free_filepair(pair_to_free);
 640         }
 641         diff_debug_queue("done copying original", &outq);
 642
 643         free(q->queue);
 644         *q = outq;
 645         diff_debug_queue("done collapsing", q);
 646
 647         for (i = 0; i < rename_dst_nr; i++)
 648                 free_filespec(rename_dst[i].two);
 649
 650         free(rename_dst);
 651         rename_dst = NULL;
 652         rename_dst_nr = rename_dst_alloc = 0;
 653         free(rename_src);
 654         rename_src = NULL;
 655         rename_src_nr = rename_src_alloc = 0;
 656         return;
 657 }