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 "object-store.h"
   8 #include "hashmap.h"
   9 #include "progress.h"
  10
  11 /* Table of rename/copy destinations */
  12
  13 static struct diff_rename_dst {
  14         struct diff_filespec *two;
  15         struct diff_filepair *pair;
  16 } *rename_dst;
  17 static int rename_dst_nr, rename_dst_alloc;
  18
  19 static int find_rename_dst(struct diff_filespec *two)
  20 {
  21         int first, last;
  22
  23         first = 0;
  24         last = rename_dst_nr;
  25         while (last > first) {
  26                 int next = first + ((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 next;
  31                 if (cmp < 0) {
  32                         last = next;
  33                         continue;
  34                 }
  35                 first = next+1;
  36         }
  37         return -first - 1;
  38 }
  39
  40 static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two)
  41 {
  42         int ofs = find_rename_dst(two);
  43         return ofs < 0 ? NULL : &rename_dst[ofs];
  44 }
  45
  46 /*
  47  * Returns 0 on success, -1 if we found a duplicate.
  48  */
  49 static int add_rename_dst(struct diff_filespec *two)
  50 {
  51         int first = find_rename_dst(two);
  52
  53         if (first >= 0)
  54                 return -1;
  55         first = -first - 1;
  56
  57         /* insert to make it at "first" */
  58         ALLOC_GROW(rename_dst, rename_dst_nr + 1, rename_dst_alloc);
  59         rename_dst_nr++;
  60         if (first < rename_dst_nr)
  61                 MOVE_ARRAY(rename_dst + first + 1, rename_dst + first,
  62                            rename_dst_nr - first - 1);
  63         rename_dst[first].two = alloc_filespec(two->path);
  64         fill_filespec(rename_dst[first].two, &two->oid, two->oid_valid,
  65                       two->mode);
  66         rename_dst[first].pair = NULL;
  67         return 0;
  68 }
  69
  70 /* Table of rename/copy src files */
  71 static struct diff_rename_src {
  72         struct diff_filepair *p;
  73         unsigned short score; /* to remember the break score */
  74 } *rename_src;
  75 static int rename_src_nr, rename_src_alloc;
  76
  77 static struct diff_rename_src *register_rename_src(struct diff_filepair *p)
  78 {
  79         int first, last;
  80         struct diff_filespec *one = p->one;
  81         unsigned short score = p->score;
  82
  83         first = 0;
  84         last = rename_src_nr;
  85         while (last > first) {
  86                 int next = first + ((last - first) >> 1);
  87                 struct diff_rename_src *src = &(rename_src[next]);
  88                 int cmp = strcmp(one->path, src->p->one->path);
  89                 if (!cmp)
  90                         return src;
  91                 if (cmp < 0) {
  92                         last = next;
  93                         continue;
  94                 }
  95                 first = next+1;
  96         }
  97
  98         /* insert to make it at "first" */
  99         ALLOC_GROW(rename_src, rename_src_nr + 1, rename_src_alloc);
 100         rename_src_nr++;
 101         if (first < rename_src_nr)
 102                 MOVE_ARRAY(rename_src + first + 1, rename_src + first,
 103                            rename_src_nr - first - 1);
 104         rename_src[first].p = p;
 105         rename_src[first].score = score;
 106         return &(rename_src[first]);
 107 }
 108
 109 static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
 110 {
 111         int src_len = strlen(src->path), dst_len = strlen(dst->path);
 112         while (src_len && dst_len) {
 113                 char c1 = src->path[--src_len];
 114                 char c2 = dst->path[--dst_len];
 115                 if (c1 != c2)
 116                         return 0;
 117                 if (c1 == '/')
 118                         return 1;
 119         }
 120         return (!src_len || src->path[src_len - 1] == '/') &&
 121                 (!dst_len || dst->path[dst_len - 1] == '/');
 122 }
 123
 124 struct diff_score {
 125         int src; /* index in rename_src */
 126         int dst; /* index in rename_dst */
 127         unsigned short score;
 128         short name_score;
 129 };
 130
 131 static int estimate_similarity(struct repository *r,
 132                                struct diff_filespec *src,
 133                                struct diff_filespec *dst,
 134                                int minimum_score)
 135 {
 136         /* src points at a file that existed in the original tree (or
 137          * optionally a file in the destination tree) and dst points
 138          * at a newly created file.  They may be quite similar, in which
 139          * case we want to say src is renamed to dst or src is copied into
 140          * dst, and then some edit has been applied to dst.
 141          *
 142          * Compare them and return how similar they are, representing
 143          * the score as an integer between 0 and MAX_SCORE.
 144          *
 145          * When there is an exact match, it is considered a better
 146          * match than anything else; the destination does not even
 147          * call into this function in that case.
 148          */
 149         unsigned long max_size, delta_size, base_size, src_copied, literal_added;
 150         int score;
 151
 152         /* We deal only with regular files.  Symlink renames are handled
 153          * only when they are exact matches --- in other words, no edits
 154          * after renaming.
 155          */
 156         if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
 157                 return 0;
 158
 159         /*
 160          * Need to check that source and destination sizes are
 161          * filled in before comparing them.
 162          *
 163          * If we already have "cnt_data" filled in, we know it's
 164          * all good (avoid checking the size for zero, as that
 165          * is a possible size - we really should have a flag to
 166          * say whether the size is valid or not!)
 167          */
 168         if (!src->cnt_data &&
 169             diff_populate_filespec(r, src, CHECK_SIZE_ONLY))
 170                 return 0;
 171         if (!dst->cnt_data &&
 172             diff_populate_filespec(r, dst, CHECK_SIZE_ONLY))
 173                 return 0;
 174
 175         max_size = ((src->size > dst->size) ? src->size : dst->size);
 176         base_size = ((src->size < dst->size) ? src->size : dst->size);
 177         delta_size = max_size - base_size;
 178
 179         /* We would not consider edits that change the file size so
 180          * drastically.  delta_size must be smaller than
 181          * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
 182          *
 183          * Note that base_size == 0 case is handled here already
 184          * and the final score computation below would not have a
 185          * divide-by-zero issue.
 186          */
 187         if (max_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
 188                 return 0;
 189
 190         if (!src->cnt_data && diff_populate_filespec(r, src, 0))
 191                 return 0;
 192         if (!dst->cnt_data && diff_populate_filespec(r, dst, 0))
 193                 return 0;
 194
 195         if (diffcore_count_changes(r, src, dst,
 196                                    &src->cnt_data, &dst->cnt_data,
 197                                    &src_copied, &literal_added))
 198                 return 0;
 199
 200         /* How similar are they?
 201          * what percentage of material in dst are from source?
 202          */
 203         if (!dst->size)
 204                 score = 0; /* should not happen */
 205         else
 206                 score = (int)(src_copied * MAX_SCORE / max_size);
 207         return score;
 208 }
 209
 210 static void record_rename_pair(int dst_index, int src_index, int score)
 211 {
 212         struct diff_filespec *src, *dst;
 213         struct diff_filepair *dp;
 214
 215         if (rename_dst[dst_index].pair)
 216                 die("internal error: dst already matched.");
 217
 218         src = rename_src[src_index].p->one;
 219         src->rename_used++;
 220         src->count++;
 221
 222         dst = rename_dst[dst_index].two;
 223         dst->count++;
 224
 225         dp = diff_queue(NULL, src, dst);
 226         dp->renamed_pair = 1;
 227         if (!strcmp(src->path, dst->path))
 228                 dp->score = rename_src[src_index].score;
 229         else
 230                 dp->score = score;
 231         rename_dst[dst_index].pair = dp;
 232 }
 233
 234 /*
 235  * We sort the rename similarity matrix with the score, in descending
 236  * order (the most similar first).
 237  */
 238 static int score_compare(const void *a_, const void *b_)
 239 {
 240         const struct diff_score *a = a_, *b = b_;
 241
 242         /* sink the unused ones to the bottom */
 243         if (a->dst < 0)
 244                 return (0 <= b->dst);
 245         else if (b->dst < 0)
 246                 return -1;
 247
 248         if (a->score == b->score)
 249                 return b->name_score - a->name_score;
 250
 251         return b->score - a->score;
 252 }
 253
 254 struct file_similarity {
 255         struct hashmap_entry entry;
 256         int index;
 257         struct diff_filespec *filespec;
 258 };
 259
 260 static unsigned int hash_filespec(struct repository *r,
 261                                   struct diff_filespec *filespec)
 262 {
 263         if (!filespec->oid_valid) {
 264                 if (diff_populate_filespec(r, filespec, 0))
 265                         return 0;
 266                 hash_object_file(r->hash_algo, filespec->data, filespec->size,
 267                                  "blob", &filespec->oid);
 268         }
 269         return oidhash(&filespec->oid);
 270 }
 271
 272 static int find_identical_files(struct hashmap *srcs,
 273                                 int dst_index,
 274                                 struct diff_options *options)
 275 {
 276         int renames = 0;
 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         unsigned int hash = hash_filespec(options->repo, target);
 281
 282         /*
 283          * Find the best source match for specified destination.
 284          */
 285         p = hashmap_get_entry_from_hash(srcs, hash, NULL,
 286                                         struct file_similarity, entry);
 287         hashmap_for_each_entry_from(srcs, p, entry) {
 288                 int score;
 289                 struct diff_filespec *source = p->filespec;
 290
 291                 /* False hash collision? */
 292                 if (!oideq(&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 repository *r,
 323                               struct hashmap *table, int index,
 324                               struct diff_filespec *filespec)
 325 {
 326         struct file_similarity *entry = xmalloc(sizeof(*entry));
 327
 328         entry->index = index;
 329         entry->filespec = filespec;
 330
 331         hashmap_entry_init(&entry->entry, hash_filespec(r, filespec));
 332         hashmap_add(table, &entry->entry);
 333 }
 334
 335 /*
 336  * Find exact renames first.
 337  *
 338  * The first round matches up the up-to-date entries,
 339  * and then during the second round we try to match
 340  * cache-dirty entries as well.
 341  */
 342 static int find_exact_renames(struct diff_options *options)
 343 {
 344         int i, renames = 0;
 345         struct hashmap file_table;
 346
 347         /* Add all sources to the hash table in reverse order, because
 348          * later on they will be retrieved in LIFO order.
 349          */
 350         hashmap_init(&file_table, NULL, NULL, rename_src_nr);
 351         for (i = rename_src_nr-1; i >= 0; i--)
 352                 insert_file_table(options->repo,
 353                                   &file_table, i,
 354                                   rename_src[i].p->one);
 355
 356         /* Walk the destinations and find best source match */
 357         for (i = 0; i < rename_dst_nr; i++)
 358                 renames += find_identical_files(&file_table, i, options);
 359
 360         /* Free the hash data structure and entries */
 361         hashmap_free_entries(&file_table, struct file_similarity, entry);
 362
 363         return renames;
 364 }
 365
 366 #define NUM_CANDIDATE_PER_DST 4
 367 static void record_if_better(struct diff_score m[], struct diff_score *o)
 368 {
 369         int i, worst;
 370
 371         /* find the worst one */
 372         worst = 0;
 373         for (i = 1; i < NUM_CANDIDATE_PER_DST; i++)
 374                 if (score_compare(&m[i], &m[worst]) > 0)
 375                         worst = i;
 376
 377         /* is it better than the worst one? */
 378         if (score_compare(&m[worst], o) > 0)
 379                 m[worst] = *o;
 380 }
 381
 382 /*
 383  * Returns:
 384  * 0 if we are under the limit;
 385  * 1 if we need to disable inexact rename detection;
 386  * 2 if we would be under the limit if we were given -C instead of -C -C.
 387  */
 388 static int too_many_rename_candidates(int num_create,
 389                                       struct diff_options *options)
 390 {
 391         int rename_limit = options->rename_limit;
 392         int num_src = rename_src_nr;
 393         int i;
 394
 395         options->needed_rename_limit = 0;
 396
 397         /*
 398          * This basically does a test for the rename matrix not
 399          * growing larger than a "rename_limit" square matrix, ie:
 400          *
 401          *    num_create * num_src > rename_limit * rename_limit
 402          */
 403         if (rename_limit <= 0)
 404                 rename_limit = 32767;
 405         if ((num_create <= rename_limit || num_src <= rename_limit) &&
 406             ((uint64_t)num_create * (uint64_t)num_src
 407              <= (uint64_t)rename_limit * (uint64_t)rename_limit))
 408                 return 0;
 409
 410         options->needed_rename_limit =
 411                 num_src > num_create ? num_src : num_create;
 412
 413         /* Are we running under -C -C? */
 414         if (!options->flags.find_copies_harder)
 415                 return 1;
 416
 417         /* Would we bust the limit if we were running under -C? */
 418         for (num_src = i = 0; i < rename_src_nr; i++) {
 419                 if (diff_unmodified_pair(rename_src[i].p))
 420                         continue;
 421                 num_src++;
 422         }
 423         if ((num_create <= rename_limit || num_src <= rename_limit) &&
 424             ((uint64_t)num_create * (uint64_t)num_src
 425              <= (uint64_t)rename_limit * (uint64_t)rename_limit))
 426                 return 2;
 427         return 1;
 428 }
 429
 430 static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, int copies)
 431 {
 432         int count = 0, i;
 433
 434         for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
 435                 struct diff_rename_dst *dst;
 436
 437                 if ((mx[i].dst < 0) ||
 438                     (mx[i].score < minimum_score))
 439                         break; /* there is no more usable pair. */
 440                 dst = &rename_dst[mx[i].dst];
 441                 if (dst->pair)
 442                         continue; /* already done, either exact or fuzzy. */
 443                 if (!copies && rename_src[mx[i].src].p->one->rename_used)
 444                         continue;
 445                 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
 446                 count++;
 447         }
 448         return count;
 449 }
 450
 451 void diffcore_rename(struct diff_options *options)
 452 {
 453         int detect_rename = options->detect_rename;
 454         int minimum_score = options->rename_score;
 455         struct diff_queue_struct *q = &diff_queued_diff;
 456         struct diff_queue_struct outq;
 457         struct diff_score *mx;
 458         int i, j, rename_count, skip_unmodified = 0;
 459         int num_create, dst_cnt;
 460         struct progress *progress = NULL;
 461
 462         if (!minimum_score)
 463                 minimum_score = DEFAULT_RENAME_SCORE;
 464
 465         for (i = 0; i < q->nr; i++) {
 466                 struct diff_filepair *p = q->queue[i];
 467                 if (!DIFF_FILE_VALID(p->one)) {
 468                         if (!DIFF_FILE_VALID(p->two))
 469                                 continue; /* unmerged */
 470                         else if (options->single_follow &&
 471                                  strcmp(options->single_follow, p->two->path))
 472                                 continue; /* not interested */
 473                         else if (!options->flags.rename_empty &&
 474                                  is_empty_blob_oid(&p->two->oid))
 475                                 continue;
 476                         else if (add_rename_dst(p->two) < 0) {
 477                                 warning("skipping rename detection, detected"
 478                                         " duplicate destination '%s'",
 479                                         p->two->path);
 480                                 goto cleanup;
 481                         }
 482                 }
 483                 else if (!options->flags.rename_empty &&
 484                          is_empty_blob_oid(&p->one->oid))
 485                         continue;
 486                 else if (!DIFF_PAIR_UNMERGED(p) && !DIFF_FILE_VALID(p->two)) {
 487                         /*
 488                          * If the source is a broken "delete", and
 489                          * they did not really want to get broken,
 490                          * that means the source actually stays.
 491                          * So we increment the "rename_used" score
 492                          * by one, to indicate ourselves as a user
 493                          */
 494                         if (p->broken_pair && !p->score)
 495                                 p->one->rename_used++;
 496                         register_rename_src(p);
 497                 }
 498                 else if (detect_rename == DIFF_DETECT_COPY) {
 499                         /*
 500                          * Increment the "rename_used" score by
 501                          * one, to indicate ourselves as a user.
 502                          */
 503                         p->one->rename_used++;
 504                         register_rename_src(p);
 505                 }
 506         }
 507         if (rename_dst_nr == 0 || rename_src_nr == 0)
 508                 goto cleanup; /* nothing to do */
 509
 510         /*
 511          * We really want to cull the candidates list early
 512          * with cheap tests in order to avoid doing deltas.
 513          */
 514         rename_count = find_exact_renames(options);
 515
 516         /* Did we only want exact renames? */
 517         if (minimum_score == MAX_SCORE)
 518                 goto cleanup;
 519
 520         /*
 521          * Calculate how many renames are left (but all the source
 522          * files still remain as options for rename/copies!)
 523          */
 524         num_create = (rename_dst_nr - rename_count);
 525
 526         /* All done? */
 527         if (!num_create)
 528                 goto cleanup;
 529
 530         switch (too_many_rename_candidates(num_create, options)) {
 531         case 1:
 532                 goto cleanup;
 533         case 2:
 534                 options->degraded_cc_to_c = 1;
 535                 skip_unmodified = 1;
 536                 break;
 537         default:
 538                 break;
 539         }
 540
 541         if (options->show_rename_progress) {
 542                 progress = start_delayed_progress(
 543                                 _("Performing inexact rename detection"),
 544                                 (uint64_t)rename_dst_nr * (uint64_t)rename_src_nr);
 545         }
 546
 547         mx = xcalloc(st_mult(NUM_CANDIDATE_PER_DST, num_create), sizeof(*mx));
 548         for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
 549                 struct diff_filespec *two = rename_dst[i].two;
 550                 struct diff_score *m;
 551
 552                 if (rename_dst[i].pair)
 553                         continue; /* dealt with exact match already. */
 554
 555                 m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST];
 556                 for (j = 0; j < NUM_CANDIDATE_PER_DST; j++)
 557                         m[j].dst = -1;
 558
 559                 for (j = 0; j < rename_src_nr; j++) {
 560                         struct diff_filespec *one = rename_src[j].p->one;
 561                         struct diff_score this_src;
 562
 563                         if (skip_unmodified &&
 564                             diff_unmodified_pair(rename_src[j].p))
 565                                 continue;
 566
 567                         this_src.score = estimate_similarity(options->repo,
 568                                                              one, two,
 569                                                              minimum_score);
 570                         this_src.name_score = basename_same(one, two);
 571                         this_src.dst = i;
 572                         this_src.src = j;
 573                         record_if_better(m, &this_src);
 574                         /*
 575                          * Once we run estimate_similarity,
 576                          * We do not need the text anymore.
 577                          */
 578                         diff_free_filespec_blob(one);
 579                         diff_free_filespec_blob(two);
 580                 }
 581                 dst_cnt++;
 582                 display_progress(progress, (uint64_t)(i+1)*(uint64_t)rename_src_nr);
 583         }
 584         stop_progress(&progress);
 585
 586         /* cost matrix sorted by most to least similar pair */
 587         STABLE_QSORT(mx, dst_cnt * NUM_CANDIDATE_PER_DST, score_compare);
 588
 589         rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
 590         if (detect_rename == DIFF_DETECT_COPY)
 591                 rename_count += find_renames(mx, dst_cnt, minimum_score, 1);
 592         free(mx);
 593
 594  cleanup:
 595         /* At this point, we have found some renames and copies and they
 596          * are recorded in rename_dst.  The original list is still in *q.
 597          */
 598         DIFF_QUEUE_CLEAR(&outq);
 599         for (i = 0; i < q->nr; i++) {
 600                 struct diff_filepair *p = q->queue[i];
 601                 struct diff_filepair *pair_to_free = NULL;
 602
 603                 if (DIFF_PAIR_UNMERGED(p)) {
 604                         diff_q(&outq, p);
 605                 }
 606                 else if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
 607                         /*
 608                          * Creation
 609                          *
 610                          * We would output this create record if it has
 611                          * not been turned into a rename/copy already.
 612                          */
 613                         struct diff_rename_dst *dst = locate_rename_dst(p->two);
 614                         if (dst && dst->pair) {
 615                                 diff_q(&outq, dst->pair);
 616                                 pair_to_free = p;
 617                         }
 618                         else
 619                                 /* no matching rename/copy source, so
 620                                  * record this as a creation.
 621                                  */
 622                                 diff_q(&outq, p);
 623                 }
 624                 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
 625                         /*
 626                          * Deletion
 627                          *
 628                          * We would output this delete record if:
 629                          *
 630                          * (1) this is a broken delete and the counterpart
 631                          *     broken create remains in the output; or
 632                          * (2) this is not a broken delete, and rename_dst
 633                          *     does not have a rename/copy to move p->one->path
 634                          *     out of existence.
 635                          *
 636                          * Otherwise, the counterpart broken create
 637                          * has been turned into a rename-edit; or
 638                          * delete did not have a matching create to
 639                          * begin with.
 640                          */
 641                         if (DIFF_PAIR_BROKEN(p)) {
 642                                 /* broken delete */
 643                                 struct diff_rename_dst *dst = locate_rename_dst(p->one);
 644                                 if (dst && dst->pair)
 645                                         /* counterpart is now rename/copy */
 646                                         pair_to_free = p;
 647                         }
 648                         else {
 649                                 if (p->one->rename_used)
 650                                         /* this path remains */
 651                                         pair_to_free = p;
 652                         }
 653
 654                         if (pair_to_free)
 655                                 ;
 656                         else
 657                                 diff_q(&outq, p);
 658                 }
 659                 else if (!diff_unmodified_pair(p))
 660                         /* all the usual ones need to be kept */
 661                         diff_q(&outq, p);
 662                 else
 663                         /* no need to keep unmodified pairs */
 664                         pair_to_free = p;
 665
 666                 if (pair_to_free)
 667                         diff_free_filepair(pair_to_free);
 668         }
 669         diff_debug_queue("done copying original", &outq);
 670
 671         free(q->queue);
 672         *q = outq;
 673         diff_debug_queue("done collapsing", q);
 674
 675         for (i = 0; i < rename_dst_nr; i++)
 676                 free_filespec(rename_dst[i].two);
 677
 678         FREE_AND_NULL(rename_dst);
 679         rename_dst_nr = rename_dst_alloc = 0;
 680         FREE_AND_NULL(rename_src);
 681         rename_src_nr = rename_src_alloc = 0;
 682         return;
 683 }