diffcore-rename.c

   1 /*
   2  *
   3  * Copyright (C) 2005 Junio C Hamano
   4  */
   5 #include "cache.h"
   6 #include "diff.h"
   7 #include "diffcore.h"
   8 #include "object-store.h"
   9 #include "hashmap.h"
  10 #include "progress.h"
  11 #include "promisor-remote.h"
  12 #include "strmap.h"
  13
  14 /* Table of rename/copy destinations */
  15
  16 static struct diff_rename_dst {
  17         struct diff_filepair *p;
  18         struct diff_filespec *filespec_to_free;
  19         int is_rename; /* false -> just a create; true -> rename or copy */
  20 } *rename_dst;
  21 static int rename_dst_nr, rename_dst_alloc;
  22 /* Mapping from break source pathname to break destination index */
  23 static struct strintmap *break_idx = NULL;
  24
  25 static struct diff_rename_dst *locate_rename_dst(struct diff_filepair *p)
  26 {
  27         /* Lookup by p->ONE->path */
  28         int idx = break_idx ? strintmap_get(break_idx, p->one->path) : -1;
  29         return (idx == -1) ? NULL : &rename_dst[idx];
  30 }
  31
  32 /*
  33  * Returns 0 on success, -1 if we found a duplicate.
  34  */
  35 static int add_rename_dst(struct diff_filepair *p)
  36 {
  37         ALLOC_GROW(rename_dst, rename_dst_nr + 1, rename_dst_alloc);
  38         rename_dst[rename_dst_nr].p = p;
  39         rename_dst[rename_dst_nr].filespec_to_free = NULL;
  40         rename_dst[rename_dst_nr].is_rename = 0;
  41         rename_dst_nr++;
  42         return 0;
  43 }
  44
  45 /* Table of rename/copy src files */
  46 static struct diff_rename_src {
  47         struct diff_filepair *p;
  48         unsigned short score; /* to remember the break score */
  49 } *rename_src;
  50 static int rename_src_nr, rename_src_alloc;
  51
  52 static void register_rename_src(struct diff_filepair *p)
  53 {
  54         if (p->broken_pair) {
  55                 if (!break_idx) {
  56                         break_idx = xmalloc(sizeof(*break_idx));
  57                         strintmap_init(break_idx, -1);
  58                 }
  59                 strintmap_set(break_idx, p->one->path, rename_dst_nr);
  60         }
  61
  62         ALLOC_GROW(rename_src, rename_src_nr + 1, rename_src_alloc);
  63         rename_src[rename_src_nr].p = p;
  64         rename_src[rename_src_nr].score = p->score;
  65         rename_src_nr++;
  66 }
  67
  68 static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
  69 {
  70         int src_len = strlen(src->path), dst_len = strlen(dst->path);
  71         while (src_len && dst_len) {
  72                 char c1 = src->path[--src_len];
  73                 char c2 = dst->path[--dst_len];
  74                 if (c1 != c2)
  75                         return 0;
  76                 if (c1 == '/')
  77                         return 1;
  78         }
  79         return (!src_len || src->path[src_len - 1] == '/') &&
  80                 (!dst_len || dst->path[dst_len - 1] == '/');
  81 }
  82
  83 struct diff_score {
  84         int src; /* index in rename_src */
  85         int dst; /* index in rename_dst */
  86         unsigned short score;
  87         short name_score;
  88 };
  89
  90 struct prefetch_options {
  91         struct repository *repo;
  92         int skip_unmodified;
  93 };
  94 static void prefetch(void *prefetch_options)
  95 {
  96         struct prefetch_options *options = prefetch_options;
  97         int i;
  98         struct oid_array to_fetch = OID_ARRAY_INIT;
  99
 100         for (i = 0; i < rename_dst_nr; i++) {
 101                 if (rename_dst[i].p->renamed_pair)
 102                         /*
 103                          * The loop in diffcore_rename() will not need these
 104                          * blobs, so skip prefetching.
 105                          */
 106                         continue; /* already found exact match */
 107                 diff_add_if_missing(options->repo, &to_fetch,
 108                                     rename_dst[i].p->two);
 109         }
 110         for (i = 0; i < rename_src_nr; i++) {
 111                 if (options->skip_unmodified &&
 112                     diff_unmodified_pair(rename_src[i].p))
 113                         /*
 114                          * The loop in diffcore_rename() will not need these
 115                          * blobs, so skip prefetching.
 116                          */
 117                         continue;
 118                 diff_add_if_missing(options->repo, &to_fetch,
 119                                     rename_src[i].p->one);
 120         }
 121         promisor_remote_get_direct(options->repo, to_fetch.oid, to_fetch.nr);
 122         oid_array_clear(&to_fetch);
 123 }
 124
 125 static int estimate_similarity(struct repository *r,
 126                                struct diff_filespec *src,
 127                                struct diff_filespec *dst,
 128                                int minimum_score,
 129                                int skip_unmodified)
 130 {
 131         /* src points at a file that existed in the original tree (or
 132          * optionally a file in the destination tree) and dst points
 133          * at a newly created file.  They may be quite similar, in which
 134          * case we want to say src is renamed to dst or src is copied into
 135          * dst, and then some edit has been applied to dst.
 136          *
 137          * Compare them and return how similar they are, representing
 138          * the score as an integer between 0 and MAX_SCORE.
 139          *
 140          * When there is an exact match, it is considered a better
 141          * match than anything else; the destination does not even
 142          * call into this function in that case.
 143          */
 144         unsigned long max_size, delta_size, base_size, src_copied, literal_added;
 145         int score;
 146         struct diff_populate_filespec_options dpf_options = {
 147                 .check_size_only = 1
 148         };
 149         struct prefetch_options prefetch_options = {r, skip_unmodified};
 150
 151         if (r == the_repository && has_promisor_remote()) {
 152                 dpf_options.missing_object_cb = prefetch;
 153                 dpf_options.missing_object_data = &prefetch_options;
 154         }
 155
 156         /* We deal only with regular files.  Symlink renames are handled
 157          * only when they are exact matches --- in other words, no edits
 158          * after renaming.
 159          */
 160         if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
 161                 return 0;
 162
 163         /*
 164          * Need to check that source and destination sizes are
 165          * filled in before comparing them.
 166          *
 167          * If we already have "cnt_data" filled in, we know it's
 168          * all good (avoid checking the size for zero, as that
 169          * is a possible size - we really should have a flag to
 170          * say whether the size is valid or not!)
 171          */
 172         if (!src->cnt_data &&
 173             diff_populate_filespec(r, src, &dpf_options))
 174                 return 0;
 175         if (!dst->cnt_data &&
 176             diff_populate_filespec(r, dst, &dpf_options))
 177                 return 0;
 178
 179         max_size = ((src->size > dst->size) ? src->size : dst->size);
 180         base_size = ((src->size < dst->size) ? src->size : dst->size);
 181         delta_size = max_size - base_size;
 182
 183         /* We would not consider edits that change the file size so
 184          * drastically.  delta_size must be smaller than
 185          * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
 186          *
 187          * Note that base_size == 0 case is handled here already
 188          * and the final score computation below would not have a
 189          * divide-by-zero issue.
 190          */
 191         if (max_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
 192                 return 0;
 193
 194         dpf_options.check_size_only = 0;
 195
 196         if (!src->cnt_data && diff_populate_filespec(r, src, &dpf_options))
 197                 return 0;
 198         if (!dst->cnt_data && diff_populate_filespec(r, dst, &dpf_options))
 199                 return 0;
 200
 201         if (diffcore_count_changes(r, src, dst,
 202                                    &src->cnt_data, &dst->cnt_data,
 203                                    &src_copied, &literal_added))
 204                 return 0;
 205
 206         /* How similar are they?
 207          * what percentage of material in dst are from source?
 208          */
 209         if (!dst->size)
 210                 score = 0; /* should not happen */
 211         else
 212                 score = (int)(src_copied * MAX_SCORE / max_size);
 213         return score;
 214 }
 215
 216 static void record_rename_pair(int dst_index, int src_index, int score)
 217 {
 218         struct diff_filepair *src = rename_src[src_index].p;
 219         struct diff_filepair *dst = rename_dst[dst_index].p;
 220
 221         if (dst->renamed_pair)
 222                 die("internal error: dst already matched.");
 223
 224         src->one->rename_used++;
 225         src->one->count++;
 226
 227         rename_dst[dst_index].filespec_to_free = dst->one;
 228         rename_dst[dst_index].is_rename = 1;
 229
 230         dst->one = src->one;
 231         dst->renamed_pair = 1;
 232         if (!strcmp(dst->one->path, dst->two->path))
 233                 dst->score = rename_src[src_index].score;
 234         else
 235                 dst->score = score;
 236 }
 237
 238 /*
 239  * We sort the rename similarity matrix with the score, in descending
 240  * order (the most similar first).
 241  */
 242 static int score_compare(const void *a_, const void *b_)
 243 {
 244         const struct diff_score *a = a_, *b = b_;
 245
 246         /* sink the unused ones to the bottom */
 247         if (a->dst < 0)
 248                 return (0 <= b->dst);
 249         else if (b->dst < 0)
 250                 return -1;
 251
 252         if (a->score == b->score)
 253                 return b->name_score - a->name_score;
 254
 255         return b->score - a->score;
 256 }
 257
 258 struct file_similarity {
 259         struct hashmap_entry entry;
 260         int index;
 261         struct diff_filespec *filespec;
 262 };
 263
 264 static unsigned int hash_filespec(struct repository *r,
 265                                   struct diff_filespec *filespec)
 266 {
 267         if (!filespec->oid_valid) {
 268                 if (diff_populate_filespec(r, filespec, NULL))
 269                         return 0;
 270                 hash_object_file(r->hash_algo, filespec->data, filespec->size,
 271                                  "blob", &filespec->oid);
 272         }
 273         return oidhash(&filespec->oid);
 274 }
 275
 276 static int find_identical_files(struct hashmap *srcs,
 277                                 int dst_index,
 278                                 struct diff_options *options)
 279 {
 280         int renames = 0;
 281         struct diff_filespec *target = rename_dst[dst_index].p->two;
 282         struct file_similarity *p, *best = NULL;
 283         int i = 100, best_score = -1;
 284         unsigned int hash = hash_filespec(options->repo, target);
 285
 286         /*
 287          * Find the best source match for specified destination.
 288          */
 289         p = hashmap_get_entry_from_hash(srcs, hash, NULL,
 290                                         struct file_similarity, entry);
 291         hashmap_for_each_entry_from(srcs, p, entry) {
 292                 int score;
 293                 struct diff_filespec *source = p->filespec;
 294
 295                 /* False hash collision? */
 296                 if (!oideq(&source->oid, &target->oid))
 297                         continue;
 298                 /* Non-regular files? If so, the modes must match! */
 299                 if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
 300                         if (source->mode != target->mode)
 301                                 continue;
 302                 }
 303                 /* Give higher scores to sources that haven't been used already */
 304                 score = !source->rename_used;
 305                 if (source->rename_used && options->detect_rename != DIFF_DETECT_COPY)
 306                         continue;
 307                 score += basename_same(source, target);
 308                 if (score > best_score) {
 309                         best = p;
 310                         best_score = score;
 311                         if (score == 2)
 312                                 break;
 313                 }
 314
 315                 /* Too many identical alternatives? Pick one */
 316                 if (!--i)
 317                         break;
 318         }
 319         if (best) {
 320                 record_rename_pair(dst_index, best->index, MAX_SCORE);
 321                 renames++;
 322         }
 323         return renames;
 324 }
 325
 326 static void insert_file_table(struct repository *r,
 327                               struct hashmap *table, int index,
 328                               struct diff_filespec *filespec)
 329 {
 330         struct file_similarity *entry = xmalloc(sizeof(*entry));
 331
 332         entry->index = index;
 333         entry->filespec = filespec;
 334
 335         hashmap_entry_init(&entry->entry, hash_filespec(r, filespec));
 336         hashmap_add(table, &entry->entry);
 337 }
 338
 339 /*
 340  * Find exact renames first.
 341  *
 342  * The first round matches up the up-to-date entries,
 343  * and then during the second round we try to match
 344  * cache-dirty entries as well.
 345  */
 346 static int find_exact_renames(struct diff_options *options)
 347 {
 348         int i, renames = 0;
 349         struct hashmap file_table;
 350
 351         /* Add all sources to the hash table in reverse order, because
 352          * later on they will be retrieved in LIFO order.
 353          */
 354         hashmap_init(&file_table, NULL, NULL, rename_src_nr);
 355         for (i = rename_src_nr-1; i >= 0; i--)
 356                 insert_file_table(options->repo,
 357                                   &file_table, i,
 358                                   rename_src[i].p->one);
 359
 360         /* Walk the destinations and find best source match */
 361         for (i = 0; i < rename_dst_nr; i++)
 362                 renames += find_identical_files(&file_table, i, options);
 363
 364         /* Free the hash data structure and entries */
 365         hashmap_clear_and_free(&file_table, struct file_similarity, entry);
 366
 367         return renames;
 368 }
 369
 370 #define NUM_CANDIDATE_PER_DST 4
 371 static void record_if_better(struct diff_score m[], struct diff_score *o)
 372 {
 373         int i, worst;
 374
 375         /* find the worst one */
 376         worst = 0;
 377         for (i = 1; i < NUM_CANDIDATE_PER_DST; i++)
 378                 if (score_compare(&m[i], &m[worst]) > 0)
 379                         worst = i;
 380
 381         /* is it better than the worst one? */
 382         if (score_compare(&m[worst], o) > 0)
 383                 m[worst] = *o;
 384 }
 385
 386 /*
 387  * Returns:
 388  * 0 if we are under the limit;
 389  * 1 if we need to disable inexact rename detection;
 390  * 2 if we would be under the limit if we were given -C instead of -C -C.
 391  */
 392 static int too_many_rename_candidates(int num_destinations, int num_sources,
 393                                       struct diff_options *options)
 394 {
 395         int rename_limit = options->rename_limit;
 396         int i, limited_sources;
 397
 398         options->needed_rename_limit = 0;
 399
 400         /*
 401          * This basically does a test for the rename matrix not
 402          * growing larger than a "rename_limit" square matrix, ie:
 403          *
 404          *    num_destinations * num_sources > rename_limit * rename_limit
 405          *
 406          * We use st_mult() to check overflow conditions; in the
 407          * exceptional circumstance that size_t isn't large enough to hold
 408          * the multiplication, the system won't be able to allocate enough
 409          * memory for the matrix anyway.
 410          */
 411         if (rename_limit <= 0)
 412                 rename_limit = 32767;
 413         if (st_mult(num_destinations, num_sources)
 414             <= st_mult(rename_limit, rename_limit))
 415                 return 0;
 416
 417         options->needed_rename_limit =
 418                 num_sources > num_destinations ? num_sources : num_destinations;
 419
 420         /* Are we running under -C -C? */
 421         if (!options->flags.find_copies_harder)
 422                 return 1;
 423
 424         /* Would we bust the limit if we were running under -C? */
 425         for (limited_sources = i = 0; i < num_sources; i++) {
 426                 if (diff_unmodified_pair(rename_src[i].p))
 427                         continue;
 428                 limited_sources++;
 429         }
 430         if (st_mult(num_destinations, limited_sources)
 431             <= st_mult(rename_limit, rename_limit))
 432                 return 2;
 433         return 1;
 434 }
 435
 436 static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, int copies)
 437 {
 438         int count = 0, i;
 439
 440         for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
 441                 struct diff_rename_dst *dst;
 442
 443                 if ((mx[i].dst < 0) ||
 444                     (mx[i].score < minimum_score))
 445                         break; /* there is no more usable pair. */
 446                 dst = &rename_dst[mx[i].dst];
 447                 if (dst->is_rename)
 448                         continue; /* already done, either exact or fuzzy. */
 449                 if (!copies && rename_src[mx[i].src].p->one->rename_used)
 450                         continue;
 451                 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
 452                 count++;
 453         }
 454         return count;
 455 }
 456
 457 void diffcore_rename(struct diff_options *options)
 458 {
 459         int detect_rename = options->detect_rename;
 460         int minimum_score = options->rename_score;
 461         struct diff_queue_struct *q = &diff_queued_diff;
 462         struct diff_queue_struct outq;
 463         struct diff_score *mx;
 464         int i, j, rename_count, skip_unmodified = 0;
 465         int num_destinations, dst_cnt;
 466         struct progress *progress = NULL;
 467
 468         trace2_region_enter("diff", "setup", options->repo);
 469         if (!minimum_score)
 470                 minimum_score = DEFAULT_RENAME_SCORE;
 471
 472         for (i = 0; i < q->nr; i++) {
 473                 struct diff_filepair *p = q->queue[i];
 474                 if (!DIFF_FILE_VALID(p->one)) {
 475                         if (!DIFF_FILE_VALID(p->two))
 476                                 continue; /* unmerged */
 477                         else if (options->single_follow &&
 478                                  strcmp(options->single_follow, p->two->path))
 479                                 continue; /* not interested */
 480                         else if (!options->flags.rename_empty &&
 481                                  is_empty_blob_oid(&p->two->oid))
 482                                 continue;
 483                         else if (add_rename_dst(p) < 0) {
 484                                 warning("skipping rename detection, detected"
 485                                         " duplicate destination '%s'",
 486                                         p->two->path);
 487                                 goto cleanup;
 488                         }
 489                 }
 490                 else if (!options->flags.rename_empty &&
 491                          is_empty_blob_oid(&p->one->oid))
 492                         continue;
 493                 else if (!DIFF_PAIR_UNMERGED(p) && !DIFF_FILE_VALID(p->two)) {
 494                         /*
 495                          * If the source is a broken "delete", and
 496                          * they did not really want to get broken,
 497                          * that means the source actually stays.
 498                          * So we increment the "rename_used" score
 499                          * by one, to indicate ourselves as a user
 500                          */
 501                         if (p->broken_pair && !p->score)
 502                                 p->one->rename_used++;
 503                         register_rename_src(p);
 504                 }
 505                 else if (detect_rename == DIFF_DETECT_COPY) {
 506                         /*
 507                          * Increment the "rename_used" score by
 508                          * one, to indicate ourselves as a user.
 509                          */
 510                         p->one->rename_used++;
 511                         register_rename_src(p);
 512                 }
 513         }
 514         trace2_region_leave("diff", "setup", options->repo);
 515         if (rename_dst_nr == 0 || rename_src_nr == 0)
 516                 goto cleanup; /* nothing to do */
 517
 518         trace2_region_enter("diff", "exact renames", options->repo);
 519         /*
 520          * We really want to cull the candidates list early
 521          * with cheap tests in order to avoid doing deltas.
 522          */
 523         rename_count = find_exact_renames(options);
 524         trace2_region_leave("diff", "exact renames", options->repo);
 525
 526         /* Did we only want exact renames? */
 527         if (minimum_score == MAX_SCORE)
 528                 goto cleanup;
 529
 530         /*
 531          * Calculate how many renames are left (but all the source
 532          * files still remain as options for rename/copies!)
 533          */
 534         num_destinations = (rename_dst_nr - rename_count);
 535
 536         /* All done? */
 537         if (!num_destinations)
 538                 goto cleanup;
 539
 540         switch (too_many_rename_candidates(num_destinations, rename_src_nr,
 541                                            options)) {
 542         case 1:
 543                 goto cleanup;
 544         case 2:
 545                 options->degraded_cc_to_c = 1;
 546                 skip_unmodified = 1;
 547                 break;
 548         default:
 549                 break;
 550         }
 551
 552         trace2_region_enter("diff", "inexact renames", options->repo);
 553         if (options->show_rename_progress) {
 554                 progress = start_delayed_progress(
 555                                 _("Performing inexact rename detection"),
 556                                 (uint64_t)num_destinations * (uint64_t)rename_src_nr);
 557         }
 558
 559         mx = xcalloc(st_mult(NUM_CANDIDATE_PER_DST, num_destinations),
 560                      sizeof(*mx));
 561         for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
 562                 struct diff_filespec *two = rename_dst[i].p->two;
 563                 struct diff_score *m;
 564
 565                 if (rename_dst[i].is_rename)
 566                         continue; /* dealt with exact match already. */
 567
 568                 m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST];
 569                 for (j = 0; j < NUM_CANDIDATE_PER_DST; j++)
 570                         m[j].dst = -1;
 571
 572                 for (j = 0; j < rename_src_nr; j++) {
 573                         struct diff_filespec *one = rename_src[j].p->one;
 574                         struct diff_score this_src;
 575
 576                         if (skip_unmodified &&
 577                             diff_unmodified_pair(rename_src[j].p))
 578                                 continue;
 579
 580                         this_src.score = estimate_similarity(options->repo,
 581                                                              one, two,
 582                                                              minimum_score,
 583                                                              skip_unmodified);
 584                         this_src.name_score = basename_same(one, two);
 585                         this_src.dst = i;
 586                         this_src.src = j;
 587                         record_if_better(m, &this_src);
 588                         /*
 589                          * Once we run estimate_similarity,
 590                          * We do not need the text anymore.
 591                          */
 592                         diff_free_filespec_blob(one);
 593                         diff_free_filespec_blob(two);
 594                 }
 595                 dst_cnt++;
 596                 display_progress(progress,
 597                                  (uint64_t)dst_cnt * (uint64_t)rename_src_nr);
 598         }
 599         stop_progress(&progress);
 600
 601         /* cost matrix sorted by most to least similar pair */
 602         STABLE_QSORT(mx, dst_cnt * NUM_CANDIDATE_PER_DST, score_compare);
 603
 604         rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
 605         if (detect_rename == DIFF_DETECT_COPY)
 606                 rename_count += find_renames(mx, dst_cnt, minimum_score, 1);
 607         free(mx);
 608         trace2_region_leave("diff", "inexact renames", options->repo);
 609
 610  cleanup:
 611         /* At this point, we have found some renames and copies and they
 612          * are recorded in rename_dst.  The original list is still in *q.
 613          */
 614         trace2_region_enter("diff", "write back to queue", options->repo);
 615         DIFF_QUEUE_CLEAR(&outq);
 616         for (i = 0; i < q->nr; i++) {
 617                 struct diff_filepair *p = q->queue[i];
 618                 struct diff_filepair *pair_to_free = NULL;
 619
 620                 if (DIFF_PAIR_UNMERGED(p)) {
 621                         diff_q(&outq, p);
 622                 }
 623                 else if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
 624                         /* Creation */
 625                         diff_q(&outq, p);
 626                 }
 627                 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
 628                         /*
 629                          * Deletion
 630                          *
 631                          * We would output this delete record if:
 632                          *
 633                          * (1) this is a broken delete and the counterpart
 634                          *     broken create remains in the output; or
 635                          * (2) this is not a broken delete, and rename_dst
 636                          *     does not have a rename/copy to move p->one->path
 637                          *     out of existence.
 638                          *
 639                          * Otherwise, the counterpart broken create
 640                          * has been turned into a rename-edit; or
 641                          * delete did not have a matching create to
 642                          * begin with.
 643                          */
 644                         if (DIFF_PAIR_BROKEN(p)) {
 645                                 /* broken delete */
 646                                 struct diff_rename_dst *dst = locate_rename_dst(p);
 647                                 if (!dst)
 648                                         BUG("tracking failed somehow; failed to find associated dst for broken pair");
 649                                 if (dst->is_rename)
 650                                         /* counterpart is now rename/copy */
 651                                         pair_to_free = p;
 652                         }
 653                         else {
 654                                 if (p->one->rename_used)
 655                                         /* this path remains */
 656                                         pair_to_free = p;
 657                         }
 658
 659                         if (!pair_to_free)
 660                                 diff_q(&outq, p);
 661                 }
 662                 else if (!diff_unmodified_pair(p))
 663                         /* all the usual ones need to be kept */
 664                         diff_q(&outq, p);
 665                 else
 666                         /* no need to keep unmodified pairs; FIXME: remove earlier? */
 667                         pair_to_free = p;
 668
 669                 if (pair_to_free)
 670                         diff_free_filepair(pair_to_free);
 671         }
 672         diff_debug_queue("done copying original", &outq);
 673
 674         free(q->queue);
 675         *q = outq;
 676         diff_debug_queue("done collapsing", q);
 677
 678         for (i = 0; i < rename_dst_nr; i++)
 679                 if (rename_dst[i].filespec_to_free)
 680                         free_filespec(rename_dst[i].filespec_to_free);
 681
 682         FREE_AND_NULL(rename_dst);
 683         rename_dst_nr = rename_dst_alloc = 0;
 684         FREE_AND_NULL(rename_src);
 685         rename_src_nr = rename_src_alloc = 0;
 686         if (break_idx) {
 687                 strintmap_clear(break_idx);
 688                 FREE_AND_NULL(break_idx);
 689         }
 690         trace2_region_leave("diff", "write back to queue", options->repo);
 691         return;
 692 }