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