diffcore-rename.c

   1 /*
   2  * Copyright (C) 2005 Junio C Hamano
   3  */
   4 #include "cache.h"
   5 #include "diff.h"
   6 #include "diffcore.h"
   7 #include "hashmap.h"
   8 #include "progress.h"
   9
  10 /* Table of rename/copy destinations */
  11
  12 static struct diff_rename_dst {
  13         struct diff_filespec *two;
  14         struct diff_filepair *pair;
  15 } *rename_dst;
  16 static int rename_dst_nr, rename_dst_alloc;
  17
  18 static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
  19                                                  int insert_ok)
  20 {
  21         int first, last;
  22
  23         first = 0;
  24         last = rename_dst_nr;
  25         while (last > first) {
  26                 int next = (last + first) >> 1;
  27                 struct diff_rename_dst *dst = &(rename_dst[next]);
  28                 int cmp = strcmp(two->path, dst->two->path);
  29                 if (!cmp)
  30                         return dst;
  31                 if (cmp < 0) {
  32                         last = next;
  33                         continue;
  34                 }
  35                 first = next+1;
  36         }
  37         /* not found */
  38         if (!insert_ok)
  39                 return NULL;
  40         /* insert to make it at "first" */
  41         if (rename_dst_alloc <= rename_dst_nr) {
  42                 rename_dst_alloc = alloc_nr(rename_dst_alloc);
  43                 rename_dst = xrealloc(rename_dst,
  44                                       rename_dst_alloc * sizeof(*rename_dst));
  45         }
  46         rename_dst_nr++;
  47         if (first < rename_dst_nr)
  48                 memmove(rename_dst + first + 1, rename_dst + first,
  49                         (rename_dst_nr - first - 1) * sizeof(*rename_dst));
  50         rename_dst[first].two = alloc_filespec(two->path);
  51         fill_filespec(rename_dst[first].two, two->sha1, two->sha1_valid, two->mode);
  52         rename_dst[first].pair = NULL;
  53         return &(rename_dst[first]);
  54 }
  55
  56 /* Table of rename/copy src files */
  57 static struct diff_rename_src {
  58         struct diff_filepair *p;
  59         unsigned short score; /* to remember the break score */
  60 } *rename_src;
  61 static int rename_src_nr, rename_src_alloc;
  62
  63 static struct diff_rename_src *register_rename_src(struct diff_filepair *p)
  64 {
  65         int first, last;
  66         struct diff_filespec *one = p->one;
  67         unsigned short score = p->score;
  68
  69         first = 0;
  70         last = rename_src_nr;
  71         while (last > first) {
  72                 int next = (last + first) >> 1;
  73                 struct diff_rename_src *src = &(rename_src[next]);
  74                 int cmp = strcmp(one->path, src->p->one->path);
  75                 if (!cmp)
  76                         return src;
  77                 if (cmp < 0) {
  78                         last = next;
  79                         continue;
  80                 }
  81                 first = next+1;
  82         }
  83
  84         /* insert to make it at "first" */
  85         if (rename_src_alloc <= rename_src_nr) {
  86                 rename_src_alloc = alloc_nr(rename_src_alloc);
  87                 rename_src = xrealloc(rename_src,
  88                                       rename_src_alloc * sizeof(*rename_src));
  89         }
  90         rename_src_nr++;
  91         if (first < rename_src_nr)
  92                 memmove(rename_src + first + 1, rename_src + first,
  93                         (rename_src_nr - first - 1) * sizeof(*rename_src));
  94         rename_src[first].p = p;
  95         rename_src[first].score = score;
  96         return &(rename_src[first]);
  97 }
  98
  99 static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
 100 {
 101         int src_len = strlen(src->path), dst_len = strlen(dst->path);
 102         while (src_len && dst_len) {
 103                 char c1 = src->path[--src_len];
 104                 char c2 = dst->path[--dst_len];
 105                 if (c1 != c2)
 106                         return 0;
 107                 if (c1 == '/')
 108                         return 1;
 109         }
 110         return (!src_len || src->path[src_len - 1] == '/') &&
 111                 (!dst_len || dst->path[dst_len - 1] == '/');
 112 }
 113
 114 struct diff_score {
 115         int src; /* index in rename_src */
 116         int dst; /* index in rename_dst */
 117         unsigned short score;
 118         short name_score;
 119 };
 120
 121 static int estimate_similarity(struct diff_filespec *src,
 122                                struct diff_filespec *dst,
 123                                int minimum_score)
 124 {
 125         /* src points at a file that existed in the original tree (or
 126          * optionally a file in the destination tree) and dst points
 127          * at a newly created file.  They may be quite similar, in which
 128          * case we want to say src is renamed to dst or src is copied into
 129          * dst, and then some edit has been applied to dst.
 130          *
 131          * Compare them and return how similar they are, representing
 132          * the score as an integer between 0 and MAX_SCORE.
 133          *
 134          * When there is an exact match, it is considered a better
 135          * match than anything else; the destination does not even
 136          * call into this function in that case.
 137          */
 138         unsigned long max_size, delta_size, base_size, src_copied, literal_added;
 139         unsigned long delta_limit;
 140         int score;
 141
 142         /* We deal only with regular files.  Symlink renames are handled
 143          * only when they are exact matches --- in other words, no edits
 144          * after renaming.
 145          */
 146         if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
 147                 return 0;
 148
 149         /*
 150          * Need to check that source and destination sizes are
 151          * filled in before comparing them.
 152          *
 153          * If we already have "cnt_data" filled in, we know it's
 154          * all good (avoid checking the size for zero, as that
 155          * is a possible size - we really should have a flag to
 156          * say whether the size is valid or not!)
 157          */
 158         if (!src->cnt_data && diff_populate_filespec(src, 1))
 159                 return 0;
 160         if (!dst->cnt_data && diff_populate_filespec(dst, 1))
 161                 return 0;
 162
 163         max_size = ((src->size > dst->size) ? src->size : dst->size);
 164         base_size = ((src->size < dst->size) ? src->size : dst->size);
 165         delta_size = max_size - base_size;
 166
 167         /* We would not consider edits that change the file size so
 168          * drastically.  delta_size must be smaller than
 169          * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
 170          *
 171          * Note that base_size == 0 case is handled here already
 172          * and the final score computation below would not have a
 173          * divide-by-zero issue.
 174          */
 175         if (max_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
 176                 return 0;
 177
 178         if (!src->cnt_data && diff_populate_filespec(src, 0))
 179                 return 0;
 180         if (!dst->cnt_data && diff_populate_filespec(dst, 0))
 181                 return 0;
 182
 183         delta_limit = (unsigned long)
 184                 (base_size * (MAX_SCORE-minimum_score) / MAX_SCORE);
 185         if (diffcore_count_changes(src, dst,
 186                                    &src->cnt_data, &dst->cnt_data,
 187                                    delta_limit,
 188                                    &src_copied, &literal_added))
 189                 return 0;
 190
 191         /* How similar are they?
 192          * what percentage of material in dst are from source?
 193          */
 194         if (!dst->size)
 195                 score = 0; /* should not happen */
 196         else
 197                 score = (int)(src_copied * MAX_SCORE / max_size);
 198         return score;
 199 }
 200
 201 static void record_rename_pair(int dst_index, int src_index, int score)
 202 {
 203         struct diff_filespec *src, *dst;
 204         struct diff_filepair *dp;
 205
 206         if (rename_dst[dst_index].pair)
 207                 die("internal error: dst already matched.");
 208
 209         src = rename_src[src_index].p->one;
 210         src->rename_used++;
 211         src->count++;
 212
 213         dst = rename_dst[dst_index].two;
 214         dst->count++;
 215
 216         dp = diff_queue(NULL, src, dst);
 217         dp->renamed_pair = 1;
 218         if (!strcmp(src->path, dst->path))
 219                 dp->score = rename_src[src_index].score;
 220         else
 221                 dp->score = score;
 222         rename_dst[dst_index].pair = dp;
 223 }
 224
 225 /*
 226  * We sort the rename similarity matrix with the score, in descending
 227  * order (the most similar first).
 228  */
 229 static int score_compare(const void *a_, const void *b_)
 230 {
 231         const struct diff_score *a = a_, *b = b_;
 232
 233         /* sink the unused ones to the bottom */
 234         if (a->dst < 0)
 235                 return (0 <= b->dst);
 236         else if (b->dst < 0)
 237                 return -1;
 238
 239         if (a->score == b->score)
 240                 return b->name_score - a->name_score;
 241
 242         return b->score - a->score;
 243 }
 244
 245 struct file_similarity {
 246         struct hashmap_entry entry;
 247         int index;
 248         struct diff_filespec *filespec;
 249 };
 250
 251 static unsigned int hash_filespec(struct diff_filespec *filespec)
 252 {
 253         unsigned int hash;
 254         if (!filespec->sha1_valid) {
 255                 if (diff_populate_filespec(filespec, 0))
 256                         return 0;
 257                 hash_sha1_file(filespec->data, filespec->size, "blob", filespec->sha1);
 258         }
 259         memcpy(&hash, filespec->sha1, sizeof(hash));
 260         return hash;
 261 }
 262
 263 static int find_identical_files(struct hashmap *srcs,
 264                                 int dst_index,
 265                                 struct diff_options *options)
 266 {
 267         int renames = 0;
 268
 269         struct diff_filespec *target = rename_dst[dst_index].two;
 270         struct file_similarity *p, *best, dst;
 271         int i = 100, best_score = -1;
 272
 273         /*
 274          * Find the best source match for specified destination.
 275          */
 276         best = NULL;
 277         hashmap_entry_init(&dst, hash_filespec(target));
 278         for (p = hashmap_get(srcs, &dst, NULL); p; p = hashmap_get_next(srcs, p)) {
 279                 int score;
 280                 struct diff_filespec *source = p->filespec;
 281
 282                 /* False hash collision? */
 283                 if (hashcmp(source->sha1, target->sha1))
 284                         continue;
 285                 /* Non-regular files? If so, the modes must match! */
 286                 if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
 287                         if (source->mode != target->mode)
 288                                 continue;
 289                 }
 290                 /* Give higher scores to sources that haven't been used already */
 291                 score = !source->rename_used;
 292                 if (source->rename_used && options->detect_rename != DIFF_DETECT_COPY)
 293                         continue;
 294                 score += basename_same(source, target);
 295                 if (score > best_score) {
 296                         best = p;
 297                         best_score = score;
 298                         if (score == 2)
 299                                 break;
 300                 }
 301
 302                 /* Too many identical alternatives? Pick one */
 303                 if (!--i)
 304                         break;
 305         }
 306         if (best) {
 307                 record_rename_pair(dst_index, best->index, MAX_SCORE);
 308                 renames++;
 309         }
 310         return renames;
 311 }
 312
 313 static void insert_file_table(struct hashmap *table, int index, struct diff_filespec *filespec)
 314 {
 315         struct file_similarity *entry = xmalloc(sizeof(*entry));
 316
 317         entry->index = index;
 318         entry->filespec = filespec;
 319
 320         hashmap_entry_init(entry, hash_filespec(filespec));
 321         hashmap_add(table, entry);
 322 }
 323
 324 /*
 325  * Find exact renames first.
 326  *
 327  * The first round matches up the up-to-date entries,
 328  * and then during the second round we try to match
 329  * cache-dirty entries as well.
 330  */
 331 static int find_exact_renames(struct diff_options *options)
 332 {
 333         int i, renames = 0;
 334         struct hashmap file_table;
 335
 336         /* Add all sources to the hash table */
 337         hashmap_init(&file_table, NULL, rename_src_nr);
 338         for (i = 0; i < rename_src_nr; i++)
 339                 insert_file_table(&file_table, i, rename_src[i].p->one);
 340
 341         /* Walk the destinations and find best source match */
 342         for (i = 0; i < rename_dst_nr; i++)
 343                 renames += find_identical_files(&file_table, i, options);
 344
 345         /* Free the hash data structure and entries */
 346         hashmap_free(&file_table, 1);
 347
 348         return renames;
 349 }
 350
 351 #define NUM_CANDIDATE_PER_DST 4
 352 static void record_if_better(struct diff_score m[], struct diff_score *o)
 353 {
 354         int i, worst;
 355
 356         /* find the worst one */
 357         worst = 0;
 358         for (i = 1; i < NUM_CANDIDATE_PER_DST; i++)
 359                 if (score_compare(&m[i], &m[worst]) > 0)
 360                         worst = i;
 361
 362         /* is it better than the worst one? */
 363         if (score_compare(&m[worst], o) > 0)
 364                 m[worst] = *o;
 365 }
 366
 367 /*
 368  * Returns:
 369  * 0 if we are under the limit;
 370  * 1 if we need to disable inexact rename detection;
 371  * 2 if we would be under the limit if we were given -C instead of -C -C.
 372  */
 373 static int too_many_rename_candidates(int num_create,
 374                                       struct diff_options *options)
 375 {
 376         int rename_limit = options->rename_limit;
 377         int num_src = rename_src_nr;
 378         int i;
 379
 380         options->needed_rename_limit = 0;
 381
 382         /*
 383          * This basically does a test for the rename matrix not
 384          * growing larger than a "rename_limit" square matrix, ie:
 385          *
 386          *    num_create * num_src > rename_limit * rename_limit
 387          *
 388          * but handles the potential overflow case specially (and we
 389          * assume at least 32-bit integers)
 390          */
 391         if (rename_limit <= 0 || rename_limit > 32767)
 392                 rename_limit = 32767;
 393         if ((num_create <= rename_limit || num_src <= rename_limit) &&
 394             (num_create * num_src <= rename_limit * rename_limit))
 395                 return 0;
 396
 397         options->needed_rename_limit =
 398                 num_src > num_create ? num_src : num_create;
 399
 400         /* Are we running under -C -C? */
 401         if (!DIFF_OPT_TST(options, FIND_COPIES_HARDER))
 402                 return 1;
 403
 404         /* Would we bust the limit if we were running under -C? */
 405         for (num_src = i = 0; i < rename_src_nr; i++) {
 406                 if (diff_unmodified_pair(rename_src[i].p))
 407                         continue;
 408                 num_src++;
 409         }
 410         if ((num_create <= rename_limit || num_src <= rename_limit) &&
 411             (num_create * num_src <= rename_limit * rename_limit))
 412                 return 2;
 413         return 1;
 414 }
 415
 416 static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, int copies)
 417 {
 418         int count = 0, i;
 419
 420         for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
 421                 struct diff_rename_dst *dst;
 422
 423                 if ((mx[i].dst < 0) ||
 424                     (mx[i].score < minimum_score))
 425                         break; /* there is no more usable pair. */
 426                 dst = &rename_dst[mx[i].dst];
 427                 if (dst->pair)
 428                         continue; /* already done, either exact or fuzzy. */
 429                 if (!copies && rename_src[mx[i].src].p->one->rename_used)
 430                         continue;
 431                 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
 432                 count++;
 433         }
 434         return count;
 435 }
 436
 437 void diffcore_rename(struct diff_options *options)
 438 {
 439         int detect_rename = options->detect_rename;
 440         int minimum_score = options->rename_score;
 441         struct diff_queue_struct *q = &diff_queued_diff;
 442         struct diff_queue_struct outq;
 443         struct diff_score *mx;
 444         int i, j, rename_count, skip_unmodified = 0;
 445         int num_create, dst_cnt;
 446         struct progress *progress = NULL;
 447
 448         if (!minimum_score)
 449                 minimum_score = DEFAULT_RENAME_SCORE;
 450
 451         for (i = 0; i < q->nr; i++) {
 452                 struct diff_filepair *p = q->queue[i];
 453                 if (!DIFF_FILE_VALID(p->one)) {
 454                         if (!DIFF_FILE_VALID(p->two))
 455                                 continue; /* unmerged */
 456                         else if (options->single_follow &&
 457                                  strcmp(options->single_follow, p->two->path))
 458                                 continue; /* not interested */
 459                         else if (!DIFF_OPT_TST(options, RENAME_EMPTY) &&
 460                                  is_empty_blob_sha1(p->two->sha1))
 461                                 continue;
 462                         else
 463                                 locate_rename_dst(p->two, 1);
 464                 }
 465                 else if (!DIFF_OPT_TST(options, RENAME_EMPTY) &&
 466                          is_empty_blob_sha1(p->one->sha1))
 467                         continue;
 468                 else if (!DIFF_PAIR_UNMERGED(p) && !DIFF_FILE_VALID(p->two)) {
 469                         /*
 470                          * If the source is a broken "delete", and
 471                          * they did not really want to get broken,
 472                          * that means the source actually stays.
 473                          * So we increment the "rename_used" score
 474                          * by one, to indicate ourselves as a user
 475                          */
 476                         if (p->broken_pair && !p->score)
 477                                 p->one->rename_used++;
 478                         register_rename_src(p);
 479                 }
 480                 else if (detect_rename == DIFF_DETECT_COPY) {
 481                         /*
 482                          * Increment the "rename_used" score by
 483                          * one, to indicate ourselves as a user.
 484                          */
 485                         p->one->rename_used++;
 486                         register_rename_src(p);
 487                 }
 488         }
 489         if (rename_dst_nr == 0 || rename_src_nr == 0)
 490                 goto cleanup; /* nothing to do */
 491
 492         /*
 493          * We really want to cull the candidates list early
 494          * with cheap tests in order to avoid doing deltas.
 495          */
 496         rename_count = find_exact_renames(options);
 497
 498         /* Did we only want exact renames? */
 499         if (minimum_score == MAX_SCORE)
 500                 goto cleanup;
 501
 502         /*
 503          * Calculate how many renames are left (but all the source
 504          * files still remain as options for rename/copies!)
 505          */
 506         num_create = (rename_dst_nr - rename_count);
 507
 508         /* All done? */
 509         if (!num_create)
 510                 goto cleanup;
 511
 512         switch (too_many_rename_candidates(num_create, options)) {
 513         case 1:
 514                 goto cleanup;
 515         case 2:
 516                 options->degraded_cc_to_c = 1;
 517                 skip_unmodified = 1;
 518                 break;
 519         default:
 520                 break;
 521         }
 522
 523         if (options->show_rename_progress) {
 524                 progress = start_progress_delay(
 525                                 _("Performing inexact rename detection"),
 526                                 rename_dst_nr * rename_src_nr, 50, 1);
 527         }
 528
 529         mx = xcalloc(num_create * NUM_CANDIDATE_PER_DST, sizeof(*mx));
 530         for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
 531                 struct diff_filespec *two = rename_dst[i].two;
 532                 struct diff_score *m;
 533
 534                 if (rename_dst[i].pair)
 535                         continue; /* dealt with exact match already. */
 536
 537                 m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST];
 538                 for (j = 0; j < NUM_CANDIDATE_PER_DST; j++)
 539                         m[j].dst = -1;
 540
 541                 for (j = 0; j < rename_src_nr; j++) {
 542                         struct diff_filespec *one = rename_src[j].p->one;
 543                         struct diff_score this_src;
 544
 545                         if (skip_unmodified &&
 546                             diff_unmodified_pair(rename_src[j].p))
 547                                 continue;
 548
 549                         this_src.score = estimate_similarity(one, two,
 550                                                              minimum_score);
 551                         this_src.name_score = basename_same(one, two);
 552                         this_src.dst = i;
 553                         this_src.src = j;
 554                         record_if_better(m, &this_src);
 555                         /*
 556                          * Once we run estimate_similarity,
 557                          * We do not need the text anymore.
 558                          */
 559                         diff_free_filespec_blob(one);
 560                         diff_free_filespec_blob(two);
 561                 }
 562                 dst_cnt++;
 563                 display_progress(progress, (i+1)*rename_src_nr);
 564         }
 565         stop_progress(&progress);
 566
 567         /* cost matrix sorted by most to least similar pair */
 568         qsort(mx, dst_cnt * NUM_CANDIDATE_PER_DST, sizeof(*mx), score_compare);
 569
 570         rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
 571         if (detect_rename == DIFF_DETECT_COPY)
 572                 rename_count += find_renames(mx, dst_cnt, minimum_score, 1);
 573         free(mx);
 574
 575  cleanup:
 576         /* At this point, we have found some renames and copies and they
 577          * are recorded in rename_dst.  The original list is still in *q.
 578          */
 579         DIFF_QUEUE_CLEAR(&outq);
 580         for (i = 0; i < q->nr; i++) {
 581                 struct diff_filepair *p = q->queue[i];
 582                 struct diff_filepair *pair_to_free = NULL;
 583
 584                 if (DIFF_PAIR_UNMERGED(p)) {
 585                         diff_q(&outq, p);
 586                 }
 587                 else if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
 588                         /*
 589                          * Creation
 590                          *
 591                          * We would output this create record if it has
 592                          * not been turned into a rename/copy already.
 593                          */
 594                         struct diff_rename_dst *dst =
 595                                 locate_rename_dst(p->two, 0);
 596                         if (dst && dst->pair) {
 597                                 diff_q(&outq, dst->pair);
 598                                 pair_to_free = p;
 599                         }
 600                         else
 601                                 /* no matching rename/copy source, so
 602                                  * record this as a creation.
 603                                  */
 604                                 diff_q(&outq, p);
 605                 }
 606                 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
 607                         /*
 608                          * Deletion
 609                          *
 610                          * We would output this delete record if:
 611                          *
 612                          * (1) this is a broken delete and the counterpart
 613                          *     broken create remains in the output; or
 614                          * (2) this is not a broken delete, and rename_dst
 615                          *     does not have a rename/copy to move p->one->path
 616                          *     out of existence.
 617                          *
 618                          * Otherwise, the counterpart broken create
 619                          * has been turned into a rename-edit; or
 620                          * delete did not have a matching create to
 621                          * begin with.
 622                          */
 623                         if (DIFF_PAIR_BROKEN(p)) {
 624                                 /* broken delete */
 625                                 struct diff_rename_dst *dst =
 626                                         locate_rename_dst(p->one, 0);
 627                                 if (dst && dst->pair)
 628                                         /* counterpart is now rename/copy */
 629                                         pair_to_free = p;
 630                         }
 631                         else {
 632                                 if (p->one->rename_used)
 633                                         /* this path remains */
 634                                         pair_to_free = p;
 635                         }
 636
 637                         if (pair_to_free)
 638                                 ;
 639                         else
 640                                 diff_q(&outq, p);
 641                 }
 642                 else if (!diff_unmodified_pair(p))
 643                         /* all the usual ones need to be kept */
 644                         diff_q(&outq, p);
 645                 else
 646                         /* no need to keep unmodified pairs */
 647                         pair_to_free = p;
 648
 649                 if (pair_to_free)
 650                         diff_free_filepair(pair_to_free);
 651         }
 652         diff_debug_queue("done copying original", &outq);
 653
 654         free(q->queue);
 655         *q = outq;
 656         diff_debug_queue("done collapsing", q);
 657
 658         for (i = 0; i < rename_dst_nr; i++)
 659                 free_filespec(rename_dst[i].two);
 660
 661         free(rename_dst);
 662         rename_dst = NULL;
 663         rename_dst_nr = rename_dst_alloc = 0;
 664         free(rename_src);
 665         rename_src = NULL;
 666         rename_src_nr = rename_src_alloc = 0;
 667         return;
 668 }