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->sha1, two->sha1_valid, two->mode);
  64         rename_dst[first].pair = NULL;
  65         return 0;
  66 }
  67
  68 /* Table of rename/copy src files */
  69 static struct diff_rename_src {
  70         struct diff_filepair *p;
  71         unsigned short score; /* to remember the break score */
  72 } *rename_src;
  73 static int rename_src_nr, rename_src_alloc;
  74
  75 static struct diff_rename_src *register_rename_src(struct diff_filepair *p)
  76 {
  77         int first, last;
  78         struct diff_filespec *one = p->one;
  79         unsigned short score = p->score;
  80
  81         first = 0;
  82         last = rename_src_nr;
  83         while (last > first) {
  84                 int next = (last + first) >> 1;
  85                 struct diff_rename_src *src = &(rename_src[next]);
  86                 int cmp = strcmp(one->path, src->p->one->path);
  87                 if (!cmp)
  88                         return src;
  89                 if (cmp < 0) {
  90                         last = next;
  91                         continue;
  92                 }
  93                 first = next+1;
  94         }
  95
  96         /* insert to make it at "first" */
  97         ALLOC_GROW(rename_src, rename_src_nr + 1, rename_src_alloc);
  98         rename_src_nr++;
  99         if (first < rename_src_nr)
 100                 memmove(rename_src + first + 1, rename_src + first,
 101                         (rename_src_nr - first - 1) * sizeof(*rename_src));
 102         rename_src[first].p = p;
 103         rename_src[first].score = score;
 104         return &(rename_src[first]);
 105 }
 106
 107 static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
 108 {
 109         int src_len = strlen(src->path), dst_len = strlen(dst->path);
 110         while (src_len && dst_len) {
 111                 char c1 = src->path[--src_len];
 112                 char c2 = dst->path[--dst_len];
 113                 if (c1 != c2)
 114                         return 0;
 115                 if (c1 == '/')
 116                         return 1;
 117         }
 118         return (!src_len || src->path[src_len - 1] == '/') &&
 119                 (!dst_len || dst->path[dst_len - 1] == '/');
 120 }
 121
 122 struct diff_score {
 123         int src; /* index in rename_src */
 124         int dst; /* index in rename_dst */
 125         unsigned short score;
 126         short name_score;
 127 };
 128
 129 static int estimate_similarity(struct diff_filespec *src,
 130                                struct diff_filespec *dst,
 131                                int minimum_score)
 132 {
 133         /* src points at a file that existed in the original tree (or
 134          * optionally a file in the destination tree) and dst points
 135          * at a newly created file.  They may be quite similar, in which
 136          * case we want to say src is renamed to dst or src is copied into
 137          * dst, and then some edit has been applied to dst.
 138          *
 139          * Compare them and return how similar they are, representing
 140          * the score as an integer between 0 and MAX_SCORE.
 141          *
 142          * When there is an exact match, it is considered a better
 143          * match than anything else; the destination does not even
 144          * call into this function in that case.
 145          */
 146         unsigned long max_size, delta_size, base_size, src_copied, literal_added;
 147         unsigned long delta_limit;
 148         int score;
 149
 150         /* We deal only with regular files.  Symlink renames are handled
 151          * only when they are exact matches --- in other words, no edits
 152          * after renaming.
 153          */
 154         if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
 155                 return 0;
 156
 157         /*
 158          * Need to check that source and destination sizes are
 159          * filled in before comparing them.
 160          *
 161          * If we already have "cnt_data" filled in, we know it's
 162          * all good (avoid checking the size for zero, as that
 163          * is a possible size - we really should have a flag to
 164          * say whether the size is valid or not!)
 165          */
 166         if (!src->cnt_data &&
 167             diff_populate_filespec(src, CHECK_SIZE_ONLY))
 168                 return 0;
 169         if (!dst->cnt_data &&
 170             diff_populate_filespec(dst, CHECK_SIZE_ONLY))
 171                 return 0;
 172
 173         max_size = ((src->size > dst->size) ? src->size : dst->size);
 174         base_size = ((src->size < dst->size) ? src->size : dst->size);
 175         delta_size = max_size - base_size;
 176
 177         /* We would not consider edits that change the file size so
 178          * drastically.  delta_size must be smaller than
 179          * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
 180          *
 181          * Note that base_size == 0 case is handled here already
 182          * and the final score computation below would not have a
 183          * divide-by-zero issue.
 184          */
 185         if (max_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
 186                 return 0;
 187
 188         if (!src->cnt_data && diff_populate_filespec(src, 0))
 189                 return 0;
 190         if (!dst->cnt_data && diff_populate_filespec(dst, 0))
 191                 return 0;
 192
 193         delta_limit = (unsigned long)
 194                 (base_size * (MAX_SCORE-minimum_score) / MAX_SCORE);
 195         if (diffcore_count_changes(src, dst,
 196                                    &src->cnt_data, &dst->cnt_data,
 197                                    delta_limit,
 198                                    &src_copied, &literal_added))
 199                 return 0;
 200
 201         /* How similar are they?
 202          * what percentage of material in dst are from source?
 203          */
 204         if (!dst->size)
 205                 score = 0; /* should not happen */
 206         else
 207                 score = (int)(src_copied * MAX_SCORE / max_size);
 208         return score;
 209 }
 210
 211 static void record_rename_pair(int dst_index, int src_index, int score)
 212 {
 213         struct diff_filespec *src, *dst;
 214         struct diff_filepair *dp;
 215
 216         if (rename_dst[dst_index].pair)
 217                 die("internal error: dst already matched.");
 218
 219         src = rename_src[src_index].p->one;
 220         src->rename_used++;
 221         src->count++;
 222
 223         dst = rename_dst[dst_index].two;
 224         dst->count++;
 225
 226         dp = diff_queue(NULL, src, dst);
 227         dp->renamed_pair = 1;
 228         if (!strcmp(src->path, dst->path))
 229                 dp->score = rename_src[src_index].score;
 230         else
 231                 dp->score = score;
 232         rename_dst[dst_index].pair = dp;
 233 }
 234
 235 /*
 236  * We sort the rename similarity matrix with the score, in descending
 237  * order (the most similar first).
 238  */
 239 static int score_compare(const void *a_, const void *b_)
 240 {
 241         const struct diff_score *a = a_, *b = b_;
 242
 243         /* sink the unused ones to the bottom */
 244         if (a->dst < 0)
 245                 return (0 <= b->dst);
 246         else if (b->dst < 0)
 247                 return -1;
 248
 249         if (a->score == b->score)
 250                 return b->name_score - a->name_score;
 251
 252         return b->score - a->score;
 253 }
 254
 255 struct file_similarity {
 256         struct hashmap_entry entry;
 257         int index;
 258         struct diff_filespec *filespec;
 259 };
 260
 261 static unsigned int hash_filespec(struct diff_filespec *filespec)
 262 {
 263         if (!filespec->sha1_valid) {
 264                 if (diff_populate_filespec(filespec, 0))
 265                         return 0;
 266                 hash_sha1_file(filespec->data, filespec->size, "blob", filespec->sha1);
 267         }
 268         return sha1hash(filespec->sha1);
 269 }
 270
 271 static int find_identical_files(struct hashmap *srcs,
 272                                 int dst_index,
 273                                 struct diff_options *options)
 274 {
 275         int renames = 0;
 276
 277         struct diff_filespec *target = rename_dst[dst_index].two;
 278         struct file_similarity *p, *best = NULL;
 279         int i = 100, best_score = -1;
 280
 281         /*
 282          * Find the best source match for specified destination.
 283          */
 284         p = hashmap_get_from_hash(srcs, hash_filespec(target), NULL);
 285         for (; p; p = hashmap_get_next(srcs, p)) {
 286                 int score;
 287                 struct diff_filespec *source = p->filespec;
 288
 289                 /* False hash collision? */
 290                 if (hashcmp(source->sha1, target->sha1))
 291                         continue;
 292                 /* Non-regular files? If so, the modes must match! */
 293                 if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
 294                         if (source->mode != target->mode)
 295                                 continue;
 296                 }
 297                 /* Give higher scores to sources that haven't been used already */
 298                 score = !source->rename_used;
 299                 if (source->rename_used && options->detect_rename != DIFF_DETECT_COPY)
 300                         continue;
 301                 score += basename_same(source, target);
 302                 if (score > best_score) {
 303                         best = p;
 304                         best_score = score;
 305                         if (score == 2)
 306                                 break;
 307                 }
 308
 309                 /* Too many identical alternatives? Pick one */
 310                 if (!--i)
 311                         break;
 312         }
 313         if (best) {
 314                 record_rename_pair(dst_index, best->index, MAX_SCORE);
 315                 renames++;
 316         }
 317         return renames;
 318 }
 319
 320 static void insert_file_table(struct hashmap *table, int index, struct diff_filespec *filespec)
 321 {
 322         struct file_similarity *entry = xmalloc(sizeof(*entry));
 323
 324         entry->index = index;
 325         entry->filespec = filespec;
 326
 327         hashmap_entry_init(entry, hash_filespec(filespec));
 328         hashmap_add(table, entry);
 329 }
 330
 331 /*
 332  * Find exact renames first.
 333  *
 334  * The first round matches up the up-to-date entries,
 335  * and then during the second round we try to match
 336  * cache-dirty entries as well.
 337  */
 338 static int find_exact_renames(struct diff_options *options)
 339 {
 340         int i, renames = 0;
 341         struct hashmap file_table;
 342
 343         /* Add all sources to the hash table in reverse order, because
 344          * later on they will be retrieved in LIFO order.
 345          */
 346         hashmap_init(&file_table, NULL, rename_src_nr);
 347         for (i = rename_src_nr-1; i >= 0; i--)
 348                 insert_file_table(&file_table, i, rename_src[i].p->one);
 349
 350         /* Walk the destinations and find best source match */
 351         for (i = 0; i < rename_dst_nr; i++)
 352                 renames += find_identical_files(&file_table, i, options);
 353
 354         /* Free the hash data structure and entries */
 355         hashmap_free(&file_table, 1);
 356
 357         return renames;
 358 }
 359
 360 #define NUM_CANDIDATE_PER_DST 4
 361 static void record_if_better(struct diff_score m[], struct diff_score *o)
 362 {
 363         int i, worst;
 364
 365         /* find the worst one */
 366         worst = 0;
 367         for (i = 1; i < NUM_CANDIDATE_PER_DST; i++)
 368                 if (score_compare(&m[i], &m[worst]) > 0)
 369                         worst = i;
 370
 371         /* is it better than the worst one? */
 372         if (score_compare(&m[worst], o) > 0)
 373                 m[worst] = *o;
 374 }
 375
 376 /*
 377  * Returns:
 378  * 0 if we are under the limit;
 379  * 1 if we need to disable inexact rename detection;
 380  * 2 if we would be under the limit if we were given -C instead of -C -C.
 381  */
 382 static int too_many_rename_candidates(int num_create,
 383                                       struct diff_options *options)
 384 {
 385         int rename_limit = options->rename_limit;
 386         int num_src = rename_src_nr;
 387         int i;
 388
 389         options->needed_rename_limit = 0;
 390
 391         /*
 392          * This basically does a test for the rename matrix not
 393          * growing larger than a "rename_limit" square matrix, ie:
 394          *
 395          *    num_create * num_src > rename_limit * rename_limit
 396          *
 397          * but handles the potential overflow case specially (and we
 398          * assume at least 32-bit integers)
 399          */
 400         if (rename_limit <= 0 || rename_limit > 32767)
 401                 rename_limit = 32767;
 402         if ((num_create <= rename_limit || num_src <= rename_limit) &&
 403             (num_create * num_src <= rename_limit * rename_limit))
 404                 return 0;
 405
 406         options->needed_rename_limit =
 407                 num_src > num_create ? num_src : num_create;
 408
 409         /* Are we running under -C -C? */
 410         if (!DIFF_OPT_TST(options, FIND_COPIES_HARDER))
 411                 return 1;
 412
 413         /* Would we bust the limit if we were running under -C? */
 414         for (num_src = i = 0; i < rename_src_nr; i++) {
 415                 if (diff_unmodified_pair(rename_src[i].p))
 416                         continue;
 417                 num_src++;
 418         }
 419         if ((num_create <= rename_limit || num_src <= rename_limit) &&
 420             (num_create * num_src <= rename_limit * rename_limit))
 421                 return 2;
 422         return 1;
 423 }
 424
 425 static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, int copies)
 426 {
 427         int count = 0, i;
 428
 429         for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
 430                 struct diff_rename_dst *dst;
 431
 432                 if ((mx[i].dst < 0) ||
 433                     (mx[i].score < minimum_score))
 434                         break; /* there is no more usable pair. */
 435                 dst = &rename_dst[mx[i].dst];
 436                 if (dst->pair)
 437                         continue; /* already done, either exact or fuzzy. */
 438                 if (!copies && rename_src[mx[i].src].p->one->rename_used)
 439                         continue;
 440                 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
 441                 count++;
 442         }
 443         return count;
 444 }
 445
 446 void diffcore_rename(struct diff_options *options)
 447 {
 448         int detect_rename = options->detect_rename;
 449         int minimum_score = options->rename_score;
 450         struct diff_queue_struct *q = &diff_queued_diff;
 451         struct diff_queue_struct outq;
 452         struct diff_score *mx;
 453         int i, j, rename_count, skip_unmodified = 0;
 454         int num_create, dst_cnt;
 455         struct progress *progress = NULL;
 456
 457         if (!minimum_score)
 458                 minimum_score = DEFAULT_RENAME_SCORE;
 459
 460         for (i = 0; i < q->nr; i++) {
 461                 struct diff_filepair *p = q->queue[i];
 462                 if (!DIFF_FILE_VALID(p->one)) {
 463                         if (!DIFF_FILE_VALID(p->two))
 464                                 continue; /* unmerged */
 465                         else if (options->single_follow &&
 466                                  strcmp(options->single_follow, p->two->path))
 467                                 continue; /* not interested */
 468                         else if (!DIFF_OPT_TST(options, RENAME_EMPTY) &&
 469                                  is_empty_blob_sha1(p->two->sha1))
 470                                 continue;
 471                         else if (add_rename_dst(p->two) < 0) {
 472                                 warning("skipping rename detection, detected"
 473                                         " duplicate destination '%s'",
 474                                         p->two->path);
 475                                 goto cleanup;
 476                         }
 477                 }
 478                 else if (!DIFF_OPT_TST(options, RENAME_EMPTY) &&
 479                          is_empty_blob_sha1(p->one->sha1))
 480                         continue;
 481                 else if (!DIFF_PAIR_UNMERGED(p) && !DIFF_FILE_VALID(p->two)) {
 482                         /*
 483                          * If the source is a broken "delete", and
 484                          * they did not really want to get broken,
 485                          * that means the source actually stays.
 486                          * So we increment the "rename_used" score
 487                          * by one, to indicate ourselves as a user
 488                          */
 489                         if (p->broken_pair && !p->score)
 490                                 p->one->rename_used++;
 491                         register_rename_src(p);
 492                 }
 493                 else if (detect_rename == DIFF_DETECT_COPY) {
 494                         /*
 495                          * Increment the "rename_used" score by
 496                          * one, to indicate ourselves as a user.
 497                          */
 498                         p->one->rename_used++;
 499                         register_rename_src(p);
 500                 }
 501         }
 502         if (rename_dst_nr == 0 || rename_src_nr == 0)
 503                 goto cleanup; /* nothing to do */
 504
 505         /*
 506          * We really want to cull the candidates list early
 507          * with cheap tests in order to avoid doing deltas.
 508          */
 509         rename_count = find_exact_renames(options);
 510
 511         /* Did we only want exact renames? */
 512         if (minimum_score == MAX_SCORE)
 513                 goto cleanup;
 514
 515         /*
 516          * Calculate how many renames are left (but all the source
 517          * files still remain as options for rename/copies!)
 518          */
 519         num_create = (rename_dst_nr - rename_count);
 520
 521         /* All done? */
 522         if (!num_create)
 523                 goto cleanup;
 524
 525         switch (too_many_rename_candidates(num_create, options)) {
 526         case 1:
 527                 goto cleanup;
 528         case 2:
 529                 options->degraded_cc_to_c = 1;
 530                 skip_unmodified = 1;
 531                 break;
 532         default:
 533                 break;
 534         }
 535
 536         if (options->show_rename_progress) {
 537                 progress = start_progress_delay(
 538                                 _("Performing inexact rename detection"),
 539                                 rename_dst_nr * rename_src_nr, 50, 1);
 540         }
 541
 542         mx = xcalloc(st_mult(num_create, NUM_CANDIDATE_PER_DST), sizeof(*mx));
 543         for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
 544                 struct diff_filespec *two = rename_dst[i].two;
 545                 struct diff_score *m;
 546
 547                 if (rename_dst[i].pair)
 548                         continue; /* dealt with exact match already. */
 549
 550                 m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST];
 551                 for (j = 0; j < NUM_CANDIDATE_PER_DST; j++)
 552                         m[j].dst = -1;
 553
 554                 for (j = 0; j < rename_src_nr; j++) {
 555                         struct diff_filespec *one = rename_src[j].p->one;
 556                         struct diff_score this_src;
 557
 558                         if (skip_unmodified &&
 559                             diff_unmodified_pair(rename_src[j].p))
 560                                 continue;
 561
 562                         this_src.score = estimate_similarity(one, two,
 563                                                              minimum_score);
 564                         this_src.name_score = basename_same(one, two);
 565                         this_src.dst = i;
 566                         this_src.src = j;
 567                         record_if_better(m, &this_src);
 568                         /*
 569                          * Once we run estimate_similarity,
 570                          * We do not need the text anymore.
 571                          */
 572                         diff_free_filespec_blob(one);
 573                         diff_free_filespec_blob(two);
 574                 }
 575                 dst_cnt++;
 576                 display_progress(progress, (i+1)*rename_src_nr);
 577         }
 578         stop_progress(&progress);
 579
 580         /* cost matrix sorted by most to least similar pair */
 581         qsort(mx, dst_cnt * NUM_CANDIDATE_PER_DST, sizeof(*mx), score_compare);
 582
 583         rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
 584         if (detect_rename == DIFF_DETECT_COPY)
 585                 rename_count += find_renames(mx, dst_cnt, minimum_score, 1);
 586         free(mx);
 587
 588  cleanup:
 589         /* At this point, we have found some renames and copies and they
 590          * are recorded in rename_dst.  The original list is still in *q.
 591          */
 592         DIFF_QUEUE_CLEAR(&outq);
 593         for (i = 0; i < q->nr; i++) {
 594                 struct diff_filepair *p = q->queue[i];
 595                 struct diff_filepair *pair_to_free = NULL;
 596
 597                 if (DIFF_PAIR_UNMERGED(p)) {
 598                         diff_q(&outq, p);
 599                 }
 600                 else if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
 601                         /*
 602                          * Creation
 603                          *
 604                          * We would output this create record if it has
 605                          * not been turned into a rename/copy already.
 606                          */
 607                         struct diff_rename_dst *dst = locate_rename_dst(p->two);
 608                         if (dst && dst->pair) {
 609                                 diff_q(&outq, dst->pair);
 610                                 pair_to_free = p;
 611                         }
 612                         else
 613                                 /* no matching rename/copy source, so
 614                                  * record this as a creation.
 615                                  */
 616                                 diff_q(&outq, p);
 617                 }
 618                 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
 619                         /*
 620                          * Deletion
 621                          *
 622                          * We would output this delete record if:
 623                          *
 624                          * (1) this is a broken delete and the counterpart
 625                          *     broken create remains in the output; or
 626                          * (2) this is not a broken delete, and rename_dst
 627                          *     does not have a rename/copy to move p->one->path
 628                          *     out of existence.
 629                          *
 630                          * Otherwise, the counterpart broken create
 631                          * has been turned into a rename-edit; or
 632                          * delete did not have a matching create to
 633                          * begin with.
 634                          */
 635                         if (DIFF_PAIR_BROKEN(p)) {
 636                                 /* broken delete */
 637                                 struct diff_rename_dst *dst = locate_rename_dst(p->one);
 638                                 if (dst && dst->pair)
 639                                         /* counterpart is now rename/copy */
 640                                         pair_to_free = p;
 641                         }
 642                         else {
 643                                 if (p->one->rename_used)
 644                                         /* this path remains */
 645                                         pair_to_free = p;
 646                         }
 647
 648                         if (pair_to_free)
 649                                 ;
 650                         else
 651                                 diff_q(&outq, p);
 652                 }
 653                 else if (!diff_unmodified_pair(p))
 654                         /* all the usual ones need to be kept */
 655                         diff_q(&outq, p);
 656                 else
 657                         /* no need to keep unmodified pairs */
 658                         pair_to_free = p;
 659
 660                 if (pair_to_free)
 661                         diff_free_filepair(pair_to_free);
 662         }
 663         diff_debug_queue("done copying original", &outq);
 664
 665         free(q->queue);
 666         *q = outq;
 667         diff_debug_queue("done collapsing", q);
 668
 669         for (i = 0; i < rename_dst_nr; i++)
 670                 free_filespec(rename_dst[i].two);
 671
 672         free(rename_dst);
 673         rename_dst = NULL;
 674         rename_dst_nr = rename_dst_alloc = 0;
 675         free(rename_src);
 676         rename_src = NULL;
 677         rename_src_nr = rename_src_alloc = 0;
 678         return;
 679 }