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 int find_rename_dst(struct diff_filespec *two)
  19 {
  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 next;
  30                 if (cmp < 0) {
  31                         last = next;
  32                         continue;
  33                 }
  34                 first = next+1;
  35         }
  36         return -first - 1;
  37 }
  38
  39 static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two)
  40 {
  41         int ofs = find_rename_dst(two);
  42         return ofs < 0 ? NULL : &rename_dst[ofs];
  43 }
  44
  45 /*
  46  * Returns 0 on success, -1 if we found a duplicate.
  47  */
  48 static int add_rename_dst(struct diff_filespec *two)
  49 {
  50         int first = find_rename_dst(two);
  51
  52         if (first >= 0)
  53                 return -1;
  54         first = -first - 1;
  55
  56         /* insert to make it at "first" */
  57         ALLOC_GROW(rename_dst, rename_dst_nr + 1, rename_dst_alloc);
  58         rename_dst_nr++;
  59         if (first < rename_dst_nr)
  60                 memmove(rename_dst + first + 1, rename_dst + first,
  61                         (rename_dst_nr - first - 1) * sizeof(*rename_dst));
  62         rename_dst[first].two = alloc_filespec(two->path);
  63         fill_filespec(rename_dst[first].two, two->oid.hash, two->oid_valid,
  64                       two->mode);
  65         rename_dst[first].pair = NULL;
  66         return 0;
  67 }
  68
  69 /* Table of rename/copy src files */
  70 static struct diff_rename_src {
  71         struct diff_filepair *p;
  72         unsigned short score; /* to remember the break score */
  73 } *rename_src;
  74 static int rename_src_nr, rename_src_alloc;
  75
  76 static struct diff_rename_src *register_rename_src(struct diff_filepair *p)
  77 {
  78         int first, last;
  79         struct diff_filespec *one = p->one;
  80         unsigned short score = p->score;
  81
  82         first = 0;
  83         last = rename_src_nr;
  84         while (last > first) {
  85                 int next = (last + first) >> 1;
  86                 struct diff_rename_src *src = &(rename_src[next]);
  87                 int cmp = strcmp(one->path, src->p->one->path);
  88                 if (!cmp)
  89                         return src;
  90                 if (cmp < 0) {
  91                         last = next;
  92                         continue;
  93                 }
  94                 first = next+1;
  95         }
  96
  97         /* insert to make it at "first" */
  98         ALLOC_GROW(rename_src, rename_src_nr + 1, rename_src_alloc);
  99         rename_src_nr++;
 100         if (first < rename_src_nr)
 101                 memmove(rename_src + first + 1, rename_src + first,
 102                         (rename_src_nr - first - 1) * sizeof(*rename_src));
 103         rename_src[first].p = p;
 104         rename_src[first].score = score;
 105         return &(rename_src[first]);
 106 }
 107
 108 static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
 109 {
 110         int src_len = strlen(src->path), dst_len = strlen(dst->path);
 111         while (src_len && dst_len) {
 112                 char c1 = src->path[--src_len];
 113                 char c2 = dst->path[--dst_len];
 114                 if (c1 != c2)
 115                         return 0;
 116                 if (c1 == '/')
 117                         return 1;
 118         }
 119         return (!src_len || src->path[src_len - 1] == '/') &&
 120                 (!dst_len || dst->path[dst_len - 1] == '/');
 121 }
 122
 123 struct diff_score {
 124         int src; /* index in rename_src */
 125         int dst; /* index in rename_dst */
 126         unsigned short score;
 127         short name_score;
 128 };
 129
 130 static int estimate_similarity(struct diff_filespec *src,
 131                                struct diff_filespec *dst,
 132                                int minimum_score)
 133 {
 134         /* src points at a file that existed in the original tree (or
 135          * optionally a file in the destination tree) and dst points
 136          * at a newly created file.  They may be quite similar, in which
 137          * case we want to say src is renamed to dst or src is copied into
 138          * dst, and then some edit has been applied to dst.
 139          *
 140          * Compare them and return how similar they are, representing
 141          * the score as an integer between 0 and MAX_SCORE.
 142          *
 143          * When there is an exact match, it is considered a better
 144          * match than anything else; the destination does not even
 145          * call into this function in that case.
 146          */
 147         unsigned long max_size, delta_size, base_size, src_copied, literal_added;
 148         unsigned long delta_limit;
 149         int score;
 150
 151         /* We deal only with regular files.  Symlink renames are handled
 152          * only when they are exact matches --- in other words, no edits
 153          * after renaming.
 154          */
 155         if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
 156                 return 0;
 157
 158         /*
 159          * Need to check that source and destination sizes are
 160          * filled in before comparing them.
 161          *
 162          * If we already have "cnt_data" filled in, we know it's
 163          * all good (avoid checking the size for zero, as that
 164          * is a possible size - we really should have a flag to
 165          * say whether the size is valid or not!)
 166          */
 167         if (!src->cnt_data &&
 168             diff_populate_filespec(src, CHECK_SIZE_ONLY))
 169                 return 0;
 170         if (!dst->cnt_data &&
 171             diff_populate_filespec(dst, CHECK_SIZE_ONLY))
 172                 return 0;
 173
 174         max_size = ((src->size > dst->size) ? src->size : dst->size);
 175         base_size = ((src->size < dst->size) ? src->size : dst->size);
 176         delta_size = max_size - base_size;
 177
 178         /* We would not consider edits that change the file size so
 179          * drastically.  delta_size must be smaller than
 180          * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
 181          *
 182          * Note that base_size == 0 case is handled here already
 183          * and the final score computation below would not have a
 184          * divide-by-zero issue.
 185          */
 186         if (max_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
 187                 return 0;
 188
 189         if (!src->cnt_data && diff_populate_filespec(src, 0))
 190                 return 0;
 191         if (!dst->cnt_data && diff_populate_filespec(dst, 0))
 192                 return 0;
 193
 194         delta_limit = (unsigned long)
 195                 (base_size * (MAX_SCORE-minimum_score) / MAX_SCORE);
 196         if (diffcore_count_changes(src, dst,
 197                                    &src->cnt_data, &dst->cnt_data,
 198                                    delta_limit,
 199                                    &src_copied, &literal_added))
 200                 return 0;
 201
 202         /* How similar are they?
 203          * what percentage of material in dst are from source?
 204          */
 205         if (!dst->size)
 206                 score = 0; /* should not happen */
 207         else
 208                 score = (int)(src_copied * MAX_SCORE / max_size);
 209         return score;
 210 }
 211
 212 static void record_rename_pair(int dst_index, int src_index, int score)
 213 {
 214         struct diff_filespec *src, *dst;
 215         struct diff_filepair *dp;
 216
 217         if (rename_dst[dst_index].pair)
 218                 die("internal error: dst already matched.");
 219
 220         src = rename_src[src_index].p->one;
 221         src->rename_used++;
 222         src->count++;
 223
 224         dst = rename_dst[dst_index].two;
 225         dst->count++;
 226
 227         dp = diff_queue(NULL, src, dst);
 228         dp->renamed_pair = 1;
 229         if (!strcmp(src->path, dst->path))
 230                 dp->score = rename_src[src_index].score;
 231         else
 232                 dp->score = score;
 233         rename_dst[dst_index].pair = dp;
 234 }
 235
 236 /*
 237  * We sort the rename similarity matrix with the score, in descending
 238  * order (the most similar first).
 239  */
 240 static int score_compare(const void *a_, const void *b_)
 241 {
 242         const struct diff_score *a = a_, *b = b_;
 243
 244         /* sink the unused ones to the bottom */
 245         if (a->dst < 0)
 246                 return (0 <= b->dst);
 247         else if (b->dst < 0)
 248                 return -1;
 249
 250         if (a->score == b->score)
 251                 return b->name_score - a->name_score;
 252
 253         return b->score - a->score;
 254 }
 255
 256 struct file_similarity {
 257         struct hashmap_entry entry;
 258         int index;
 259         struct diff_filespec *filespec;
 260 };
 261
 262 static unsigned int hash_filespec(struct diff_filespec *filespec)
 263 {
 264         if (!filespec->oid_valid) {
 265                 if (diff_populate_filespec(filespec, 0))
 266                         return 0;
 267                 hash_sha1_file(filespec->data, filespec->size, "blob",
 268                                filespec->oid.hash);
 269         }
 270         return sha1hash(filespec->oid.hash);
 271 }
 272
 273 static int find_identical_files(struct hashmap *srcs,
 274                                 int dst_index,
 275                                 struct diff_options *options)
 276 {
 277         int renames = 0;
 278
 279         struct diff_filespec *target = rename_dst[dst_index].two;
 280         struct file_similarity *p, *best = NULL;
 281         int i = 100, best_score = -1;
 282
 283         /*
 284          * Find the best source match for specified destination.
 285          */
 286         p = hashmap_get_from_hash(srcs, hash_filespec(target), NULL);
 287         for (; p; p = hashmap_get_next(srcs, p)) {
 288                 int score;
 289                 struct diff_filespec *source = p->filespec;
 290
 291                 /* False hash collision? */
 292                 if (oidcmp(&source->oid, &target->oid))
 293                         continue;
 294                 /* Non-regular files? If so, the modes must match! */
 295                 if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
 296                         if (source->mode != target->mode)
 297                                 continue;
 298                 }
 299                 /* Give higher scores to sources that haven't been used already */
 300                 score = !source->rename_used;
 301                 if (source->rename_used && options->detect_rename != DIFF_DETECT_COPY)
 302                         continue;
 303                 score += basename_same(source, target);
 304                 if (score > best_score) {
 305                         best = p;
 306                         best_score = score;
 307                         if (score == 2)
 308                                 break;
 309                 }
 310
 311                 /* Too many identical alternatives? Pick one */
 312                 if (!--i)
 313                         break;
 314         }
 315         if (best) {
 316                 record_rename_pair(dst_index, best->index, MAX_SCORE);
 317                 renames++;
 318         }
 319         return renames;
 320 }
 321
 322 static void insert_file_table(struct hashmap *table, int index, struct diff_filespec *filespec)
 323 {
 324         struct file_similarity *entry = xmalloc(sizeof(*entry));
 325
 326         entry->index = index;
 327         entry->filespec = filespec;
 328
 329         hashmap_entry_init(entry, hash_filespec(filespec));
 330         hashmap_add(table, entry);
 331 }
 332
 333 /*
 334  * Find exact renames first.
 335  *
 336  * The first round matches up the up-to-date entries,
 337  * and then during the second round we try to match
 338  * cache-dirty entries as well.
 339  */
 340 static int find_exact_renames(struct diff_options *options)
 341 {
 342         int i, renames = 0;
 343         struct hashmap file_table;
 344
 345         /* Add all sources to the hash table in reverse order, because
 346          * later on they will be retrieved in LIFO order.
 347          */
 348         hashmap_init(&file_table, NULL, rename_src_nr);
 349         for (i = rename_src_nr-1; i >= 0; i--)
 350                 insert_file_table(&file_table, i, rename_src[i].p->one);
 351
 352         /* Walk the destinations and find best source match */
 353         for (i = 0; i < rename_dst_nr; i++)
 354                 renames += find_identical_files(&file_table, i, options);
 355
 356         /* Free the hash data structure and entries */
 357         hashmap_free(&file_table, 1);
 358
 359         return renames;
 360 }
 361
 362 #define NUM_CANDIDATE_PER_DST 4
 363 static void record_if_better(struct diff_score m[], struct diff_score *o)
 364 {
 365         int i, worst;
 366
 367         /* find the worst one */
 368         worst = 0;
 369         for (i = 1; i < NUM_CANDIDATE_PER_DST; i++)
 370                 if (score_compare(&m[i], &m[worst]) > 0)
 371                         worst = i;
 372
 373         /* is it better than the worst one? */
 374         if (score_compare(&m[worst], o) > 0)
 375                 m[worst] = *o;
 376 }
 377
 378 /*
 379  * Returns:
 380  * 0 if we are under the limit;
 381  * 1 if we need to disable inexact rename detection;
 382  * 2 if we would be under the limit if we were given -C instead of -C -C.
 383  */
 384 static int too_many_rename_candidates(int num_create,
 385                                       struct diff_options *options)
 386 {
 387         int rename_limit = options->rename_limit;
 388         int num_src = rename_src_nr;
 389         int i;
 390
 391         options->needed_rename_limit = 0;
 392
 393         /*
 394          * This basically does a test for the rename matrix not
 395          * growing larger than a "rename_limit" square matrix, ie:
 396          *
 397          *    num_create * num_src > rename_limit * rename_limit
 398          *
 399          * but handles the potential overflow case specially (and we
 400          * assume at least 32-bit integers)
 401          */
 402         if (rename_limit <= 0 || rename_limit > 32767)
 403                 rename_limit = 32767;
 404         if ((num_create <= rename_limit || num_src <= rename_limit) &&
 405             (num_create * num_src <= rename_limit * rename_limit))
 406                 return 0;
 407
 408         options->needed_rename_limit =
 409                 num_src > num_create ? num_src : num_create;
 410
 411         /* Are we running under -C -C? */
 412         if (!DIFF_OPT_TST(options, FIND_COPIES_HARDER))
 413                 return 1;
 414
 415         /* Would we bust the limit if we were running under -C? */
 416         for (num_src = i = 0; i < rename_src_nr; i++) {
 417                 if (diff_unmodified_pair(rename_src[i].p))
 418                         continue;
 419                 num_src++;
 420         }
 421         if ((num_create <= rename_limit || num_src <= rename_limit) &&
 422             (num_create * num_src <= rename_limit * rename_limit))
 423                 return 2;
 424         return 1;
 425 }
 426
 427 static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, int copies)
 428 {
 429         int count = 0, i;
 430
 431         for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
 432                 struct diff_rename_dst *dst;
 433
 434                 if ((mx[i].dst < 0) ||
 435                     (mx[i].score < minimum_score))
 436                         break; /* there is no more usable pair. */
 437                 dst = &rename_dst[mx[i].dst];
 438                 if (dst->pair)
 439                         continue; /* already done, either exact or fuzzy. */
 440                 if (!copies && rename_src[mx[i].src].p->one->rename_used)
 441                         continue;
 442                 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
 443                 count++;
 444         }
 445         return count;
 446 }
 447
 448 void diffcore_rename(struct diff_options *options)
 449 {
 450         int detect_rename = options->detect_rename;
 451         int minimum_score = options->rename_score;
 452         struct diff_queue_struct *q = &diff_queued_diff;
 453         struct diff_queue_struct outq;
 454         struct diff_score *mx;
 455         int i, j, rename_count, skip_unmodified = 0;
 456         int num_create, dst_cnt;
 457         struct progress *progress = NULL;
 458
 459         if (!minimum_score)
 460                 minimum_score = DEFAULT_RENAME_SCORE;
 461
 462         for (i = 0; i < q->nr; i++) {
 463                 struct diff_filepair *p = q->queue[i];
 464                 if (!DIFF_FILE_VALID(p->one)) {
 465                         if (!DIFF_FILE_VALID(p->two))
 466                                 continue; /* unmerged */
 467                         else if (options->single_follow &&
 468                                  strcmp(options->single_follow, p->two->path))
 469                                 continue; /* not interested */
 470                         else if (!DIFF_OPT_TST(options, RENAME_EMPTY) &&
 471                                  is_empty_blob_sha1(p->two->oid.hash))
 472                                 continue;
 473                         else if (add_rename_dst(p->two) < 0) {
 474                                 warning("skipping rename detection, detected"
 475                                         " duplicate destination '%s'",
 476                                         p->two->path);
 477                                 goto cleanup;
 478                         }
 479                 }
 480                 else if (!DIFF_OPT_TST(options, RENAME_EMPTY) &&
 481                          is_empty_blob_sha1(p->one->oid.hash))
 482                         continue;
 483                 else if (!DIFF_PAIR_UNMERGED(p) && !DIFF_FILE_VALID(p->two)) {
 484                         /*
 485                          * If the source is a broken "delete", and
 486                          * they did not really want to get broken,
 487                          * that means the source actually stays.
 488                          * So we increment the "rename_used" score
 489                          * by one, to indicate ourselves as a user
 490                          */
 491                         if (p->broken_pair && !p->score)
 492                                 p->one->rename_used++;
 493                         register_rename_src(p);
 494                 }
 495                 else if (detect_rename == DIFF_DETECT_COPY) {
 496                         /*
 497                          * Increment the "rename_used" score by
 498                          * one, to indicate ourselves as a user.
 499                          */
 500                         p->one->rename_used++;
 501                         register_rename_src(p);
 502                 }
 503         }
 504         if (rename_dst_nr == 0 || rename_src_nr == 0)
 505                 goto cleanup; /* nothing to do */
 506
 507         /*
 508          * We really want to cull the candidates list early
 509          * with cheap tests in order to avoid doing deltas.
 510          */
 511         rename_count = find_exact_renames(options);
 512
 513         /* Did we only want exact renames? */
 514         if (minimum_score == MAX_SCORE)
 515                 goto cleanup;
 516
 517         /*
 518          * Calculate how many renames are left (but all the source
 519          * files still remain as options for rename/copies!)
 520          */
 521         num_create = (rename_dst_nr - rename_count);
 522
 523         /* All done? */
 524         if (!num_create)
 525                 goto cleanup;
 526
 527         switch (too_many_rename_candidates(num_create, options)) {
 528         case 1:
 529                 goto cleanup;
 530         case 2:
 531                 options->degraded_cc_to_c = 1;
 532                 skip_unmodified = 1;
 533                 break;
 534         default:
 535                 break;
 536         }
 537
 538         if (options->show_rename_progress) {
 539                 progress = start_progress_delay(
 540                                 _("Performing inexact rename detection"),
 541                                 rename_dst_nr * rename_src_nr, 50, 1);
 542         }
 543
 544         mx = xcalloc(st_mult(NUM_CANDIDATE_PER_DST, num_create), sizeof(*mx));
 545         for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
 546                 struct diff_filespec *two = rename_dst[i].two;
 547                 struct diff_score *m;
 548
 549                 if (rename_dst[i].pair)
 550                         continue; /* dealt with exact match already. */
 551
 552                 m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST];
 553                 for (j = 0; j < NUM_CANDIDATE_PER_DST; j++)
 554                         m[j].dst = -1;
 555
 556                 for (j = 0; j < rename_src_nr; j++) {
 557                         struct diff_filespec *one = rename_src[j].p->one;
 558                         struct diff_score this_src;
 559
 560                         if (skip_unmodified &&
 561                             diff_unmodified_pair(rename_src[j].p))
 562                                 continue;
 563
 564                         this_src.score = estimate_similarity(one, two,
 565                                                              minimum_score);
 566                         this_src.name_score = basename_same(one, two);
 567                         this_src.dst = i;
 568                         this_src.src = j;
 569                         record_if_better(m, &this_src);
 570                         /*
 571                          * Once we run estimate_similarity,
 572                          * We do not need the text anymore.
 573                          */
 574                         diff_free_filespec_blob(one);
 575                         diff_free_filespec_blob(two);
 576                 }
 577                 dst_cnt++;
 578                 display_progress(progress, (i+1)*rename_src_nr);
 579         }
 580         stop_progress(&progress);
 581
 582         /* cost matrix sorted by most to least similar pair */
 583         QSORT(mx, dst_cnt * NUM_CANDIDATE_PER_DST, score_compare);
 584
 585         rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
 586         if (detect_rename == DIFF_DETECT_COPY)
 587                 rename_count += find_renames(mx, dst_cnt, minimum_score, 1);
 588         free(mx);
 589
 590  cleanup:
 591         /* At this point, we have found some renames and copies and they
 592          * are recorded in rename_dst.  The original list is still in *q.
 593          */
 594         DIFF_QUEUE_CLEAR(&outq);
 595         for (i = 0; i < q->nr; i++) {
 596                 struct diff_filepair *p = q->queue[i];
 597                 struct diff_filepair *pair_to_free = NULL;
 598
 599                 if (DIFF_PAIR_UNMERGED(p)) {
 600                         diff_q(&outq, p);
 601                 }
 602                 else if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
 603                         /*
 604                          * Creation
 605                          *
 606                          * We would output this create record if it has
 607                          * not been turned into a rename/copy already.
 608                          */
 609                         struct diff_rename_dst *dst = locate_rename_dst(p->two);
 610                         if (dst && dst->pair) {
 611                                 diff_q(&outq, dst->pair);
 612                                 pair_to_free = p;
 613                         }
 614                         else
 615                                 /* no matching rename/copy source, so
 616                                  * record this as a creation.
 617                                  */
 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->one);
 640                                 if (dst && dst->pair)
 641                                         /* counterpart is now rename/copy */
 642                                         pair_to_free = p;
 643                         }
 644                         else {
 645                                 if (p->one->rename_used)
 646                                         /* this path remains */
 647                                         pair_to_free = p;
 648                         }
 649
 650                         if (pair_to_free)
 651                                 ;
 652                         else
 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 */
 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                 free_filespec(rename_dst[i].two);
 673
 674         free(rename_dst);
 675         rename_dst = NULL;
 676         rename_dst_nr = rename_dst_alloc = 0;
 677         free(rename_src);
 678         rename_src = NULL;
 679         rename_src_nr = rename_src_alloc = 0;
 680         return;
 681 }