diffcore-rename.con commit Fourth batch (bc12974)
   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
  13static struct diff_rename_dst {
  14        struct diff_filespec *two;
  15        struct diff_filepair *pair;
  16} *rename_dst;
  17static int rename_dst_nr, rename_dst_alloc;
  18
  19static 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
  40static 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 */
  49static 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 */
  71static struct diff_rename_src {
  72        struct diff_filepair *p;
  73        unsigned short score; /* to remember the break score */
  74} *rename_src;
  75static int rename_src_nr, rename_src_alloc;
  76
  77static 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
 109static 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
 124struct 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
 131static 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
 210static 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 */
 238static 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
 254struct file_similarity {
 255        struct hashmap_entry entry;
 256        int index;
 257        struct diff_filespec *filespec;
 258};
 259
 260static 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(filespec->data, filespec->size, "blob",
 267                                 &filespec->oid);
 268        }
 269        return oidhash(&filespec->oid);
 270}
 271
 272static int find_identical_files(struct hashmap *srcs,
 273                                int dst_index,
 274                                struct diff_options *options)
 275{
 276        int renames = 0;
 277
 278        struct diff_filespec *target = rename_dst[dst_index].two;
 279        struct file_similarity *p, *best = NULL;
 280        int i = 100, best_score = -1;
 281
 282        /*
 283         * Find the best source match for specified destination.
 284         */
 285        p = hashmap_get_from_hash(srcs,
 286                                  hash_filespec(options->repo, target),
 287                                  NULL);
 288        for (; p; p = hashmap_get_next(srcs, p)) {
 289                int score;
 290                struct diff_filespec *source = p->filespec;
 291
 292                /* False hash collision? */
 293                if (!oideq(&source->oid, &target->oid))
 294                        continue;
 295                /* Non-regular files? If so, the modes must match! */
 296                if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
 297                        if (source->mode != target->mode)
 298                                continue;
 299                }
 300                /* Give higher scores to sources that haven't been used already */
 301                score = !source->rename_used;
 302                if (source->rename_used && options->detect_rename != DIFF_DETECT_COPY)
 303                        continue;
 304                score += basename_same(source, target);
 305                if (score > best_score) {
 306                        best = p;
 307                        best_score = score;
 308                        if (score == 2)
 309                                break;
 310                }
 311
 312                /* Too many identical alternatives? Pick one */
 313                if (!--i)
 314                        break;
 315        }
 316        if (best) {
 317                record_rename_pair(dst_index, best->index, MAX_SCORE);
 318                renames++;
 319        }
 320        return renames;
 321}
 322
 323static void insert_file_table(struct repository *r,
 324                              struct hashmap *table, int index,
 325                              struct diff_filespec *filespec)
 326{
 327        struct file_similarity *entry = xmalloc(sizeof(*entry));
 328
 329        entry->index = index;
 330        entry->filespec = filespec;
 331
 332        hashmap_entry_init(entry, hash_filespec(r, filespec));
 333        hashmap_add(table, entry);
 334}
 335
 336/*
 337 * Find exact renames first.
 338 *
 339 * The first round matches up the up-to-date entries,
 340 * and then during the second round we try to match
 341 * cache-dirty entries as well.
 342 */
 343static int find_exact_renames(struct diff_options *options)
 344{
 345        int i, renames = 0;
 346        struct hashmap file_table;
 347
 348        /* Add all sources to the hash table in reverse order, because
 349         * later on they will be retrieved in LIFO order.
 350         */
 351        hashmap_init(&file_table, NULL, NULL, rename_src_nr);
 352        for (i = rename_src_nr-1; i >= 0; i--)
 353                insert_file_table(options->repo,
 354                                  &file_table, i,
 355                                  rename_src[i].p->one);
 356
 357        /* Walk the destinations and find best source match */
 358        for (i = 0; i < rename_dst_nr; i++)
 359                renames += find_identical_files(&file_table, i, options);
 360
 361        /* Free the hash data structure and entries */
 362        hashmap_free(&file_table, 1);
 363
 364        return renames;
 365}
 366
 367#define NUM_CANDIDATE_PER_DST 4
 368static void record_if_better(struct diff_score m[], struct diff_score *o)
 369{
 370        int i, worst;
 371
 372        /* find the worst one */
 373        worst = 0;
 374        for (i = 1; i < NUM_CANDIDATE_PER_DST; i++)
 375                if (score_compare(&m[i], &m[worst]) > 0)
 376                        worst = i;
 377
 378        /* is it better than the worst one? */
 379        if (score_compare(&m[worst], o) > 0)
 380                m[worst] = *o;
 381}
 382
 383/*
 384 * Returns:
 385 * 0 if we are under the limit;
 386 * 1 if we need to disable inexact rename detection;
 387 * 2 if we would be under the limit if we were given -C instead of -C -C.
 388 */
 389static int too_many_rename_candidates(int num_create,
 390                                      struct diff_options *options)
 391{
 392        int rename_limit = options->rename_limit;
 393        int num_src = rename_src_nr;
 394        int i;
 395
 396        options->needed_rename_limit = 0;
 397
 398        /*
 399         * This basically does a test for the rename matrix not
 400         * growing larger than a "rename_limit" square matrix, ie:
 401         *
 402         *    num_create * num_src > rename_limit * rename_limit
 403         */
 404        if (rename_limit <= 0)
 405                rename_limit = 32767;
 406        if ((num_create <= rename_limit || num_src <= rename_limit) &&
 407            ((uint64_t)num_create * (uint64_t)num_src
 408             <= (uint64_t)rename_limit * (uint64_t)rename_limit))
 409                return 0;
 410
 411        options->needed_rename_limit =
 412                num_src > num_create ? num_src : num_create;
 413
 414        /* Are we running under -C -C? */
 415        if (!options->flags.find_copies_harder)
 416                return 1;
 417
 418        /* Would we bust the limit if we were running under -C? */
 419        for (num_src = i = 0; i < rename_src_nr; i++) {
 420                if (diff_unmodified_pair(rename_src[i].p))
 421                        continue;
 422                num_src++;
 423        }
 424        if ((num_create <= rename_limit || num_src <= rename_limit) &&
 425            ((uint64_t)num_create * (uint64_t)num_src
 426             <= (uint64_t)rename_limit * (uint64_t)rename_limit))
 427                return 2;
 428        return 1;
 429}
 430
 431static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, int copies)
 432{
 433        int count = 0, i;
 434
 435        for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
 436                struct diff_rename_dst *dst;
 437
 438                if ((mx[i].dst < 0) ||
 439                    (mx[i].score < minimum_score))
 440                        break; /* there is no more usable pair. */
 441                dst = &rename_dst[mx[i].dst];
 442                if (dst->pair)
 443                        continue; /* already done, either exact or fuzzy. */
 444                if (!copies && rename_src[mx[i].src].p->one->rename_used)
 445                        continue;
 446                record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
 447                count++;
 448        }
 449        return count;
 450}
 451
 452void diffcore_rename(struct diff_options *options)
 453{
 454        int detect_rename = options->detect_rename;
 455        int minimum_score = options->rename_score;
 456        struct diff_queue_struct *q = &diff_queued_diff;
 457        struct diff_queue_struct outq;
 458        struct diff_score *mx;
 459        int i, j, rename_count, skip_unmodified = 0;
 460        int num_create, dst_cnt;
 461        struct progress *progress = NULL;
 462
 463        if (!minimum_score)
 464                minimum_score = DEFAULT_RENAME_SCORE;
 465
 466        for (i = 0; i < q->nr; i++) {
 467                struct diff_filepair *p = q->queue[i];
 468                if (!DIFF_FILE_VALID(p->one)) {
 469                        if (!DIFF_FILE_VALID(p->two))
 470                                continue; /* unmerged */
 471                        else if (options->single_follow &&
 472                                 strcmp(options->single_follow, p->two->path))
 473                                continue; /* not interested */
 474                        else if (!options->flags.rename_empty &&
 475                                 is_empty_blob_oid(&p->two->oid))
 476                                continue;
 477                        else if (add_rename_dst(p->two) < 0) {
 478                                warning("skipping rename detection, detected"
 479                                        " duplicate destination '%s'",
 480                                        p->two->path);
 481                                goto cleanup;
 482                        }
 483                }
 484                else if (!options->flags.rename_empty &&
 485                         is_empty_blob_oid(&p->one->oid))
 486                        continue;
 487                else if (!DIFF_PAIR_UNMERGED(p) && !DIFF_FILE_VALID(p->two)) {
 488                        /*
 489                         * If the source is a broken "delete", and
 490                         * they did not really want to get broken,
 491                         * that means the source actually stays.
 492                         * So we increment the "rename_used" score
 493                         * by one, to indicate ourselves as a user
 494                         */
 495                        if (p->broken_pair && !p->score)
 496                                p->one->rename_used++;
 497                        register_rename_src(p);
 498                }
 499                else if (detect_rename == DIFF_DETECT_COPY) {
 500                        /*
 501                         * Increment the "rename_used" score by
 502                         * one, to indicate ourselves as a user.
 503                         */
 504                        p->one->rename_used++;
 505                        register_rename_src(p);
 506                }
 507        }
 508        if (rename_dst_nr == 0 || rename_src_nr == 0)
 509                goto cleanup; /* nothing to do */
 510
 511        /*
 512         * We really want to cull the candidates list early
 513         * with cheap tests in order to avoid doing deltas.
 514         */
 515        rename_count = find_exact_renames(options);
 516
 517        /* Did we only want exact renames? */
 518        if (minimum_score == MAX_SCORE)
 519                goto cleanup;
 520
 521        /*
 522         * Calculate how many renames are left (but all the source
 523         * files still remain as options for rename/copies!)
 524         */
 525        num_create = (rename_dst_nr - rename_count);
 526
 527        /* All done? */
 528        if (!num_create)
 529                goto cleanup;
 530
 531        switch (too_many_rename_candidates(num_create, options)) {
 532        case 1:
 533                goto cleanup;
 534        case 2:
 535                options->degraded_cc_to_c = 1;
 536                skip_unmodified = 1;
 537                break;
 538        default:
 539                break;
 540        }
 541
 542        if (options->show_rename_progress) {
 543                progress = start_delayed_progress(
 544                                _("Performing inexact rename detection"),
 545                                (uint64_t)rename_dst_nr * (uint64_t)rename_src_nr);
 546        }
 547
 548        mx = xcalloc(st_mult(NUM_CANDIDATE_PER_DST, num_create), sizeof(*mx));
 549        for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
 550                struct diff_filespec *two = rename_dst[i].two;
 551                struct diff_score *m;
 552
 553                if (rename_dst[i].pair)
 554                        continue; /* dealt with exact match already. */
 555
 556                m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST];
 557                for (j = 0; j < NUM_CANDIDATE_PER_DST; j++)
 558                        m[j].dst = -1;
 559
 560                for (j = 0; j < rename_src_nr; j++) {
 561                        struct diff_filespec *one = rename_src[j].p->one;
 562                        struct diff_score this_src;
 563
 564                        if (skip_unmodified &&
 565                            diff_unmodified_pair(rename_src[j].p))
 566                                continue;
 567
 568                        this_src.score = estimate_similarity(options->repo,
 569                                                             one, two,
 570                                                             minimum_score);
 571                        this_src.name_score = basename_same(one, two);
 572                        this_src.dst = i;
 573                        this_src.src = j;
 574                        record_if_better(m, &this_src);
 575                        /*
 576                         * Once we run estimate_similarity,
 577                         * We do not need the text anymore.
 578                         */
 579                        diff_free_filespec_blob(one);
 580                        diff_free_filespec_blob(two);
 581                }
 582                dst_cnt++;
 583                display_progress(progress, (uint64_t)(i+1)*(uint64_t)rename_src_nr);
 584        }
 585        stop_progress(&progress);
 586
 587        /* cost matrix sorted by most to least similar pair */
 588        QSORT(mx, dst_cnt * NUM_CANDIDATE_PER_DST, score_compare);
 589
 590        rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
 591        if (detect_rename == DIFF_DETECT_COPY)
 592                rename_count += find_renames(mx, dst_cnt, minimum_score, 1);
 593        free(mx);
 594
 595 cleanup:
 596        /* At this point, we have found some renames and copies and they
 597         * are recorded in rename_dst.  The original list is still in *q.
 598         */
 599        DIFF_QUEUE_CLEAR(&outq);
 600        for (i = 0; i < q->nr; i++) {
 601                struct diff_filepair *p = q->queue[i];
 602                struct diff_filepair *pair_to_free = NULL;
 603
 604                if (DIFF_PAIR_UNMERGED(p)) {
 605                        diff_q(&outq, p);
 606                }
 607                else if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
 608                        /*
 609                         * Creation
 610                         *
 611                         * We would output this create record if it has
 612                         * not been turned into a rename/copy already.
 613                         */
 614                        struct diff_rename_dst *dst = locate_rename_dst(p->two);
 615                        if (dst && dst->pair) {
 616                                diff_q(&outq, dst->pair);
 617                                pair_to_free = p;
 618                        }
 619                        else
 620                                /* no matching rename/copy source, so
 621                                 * record this as a creation.
 622                                 */
 623                                diff_q(&outq, p);
 624                }
 625                else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
 626                        /*
 627                         * Deletion
 628                         *
 629                         * We would output this delete record if:
 630                         *
 631                         * (1) this is a broken delete and the counterpart
 632                         *     broken create remains in the output; or
 633                         * (2) this is not a broken delete, and rename_dst
 634                         *     does not have a rename/copy to move p->one->path
 635                         *     out of existence.
 636                         *
 637                         * Otherwise, the counterpart broken create
 638                         * has been turned into a rename-edit; or
 639                         * delete did not have a matching create to
 640                         * begin with.
 641                         */
 642                        if (DIFF_PAIR_BROKEN(p)) {
 643                                /* broken delete */
 644                                struct diff_rename_dst *dst = locate_rename_dst(p->one);
 645                                if (dst && dst->pair)
 646                                        /* counterpart is now rename/copy */
 647                                        pair_to_free = p;
 648                        }
 649                        else {
 650                                if (p->one->rename_used)
 651                                        /* this path remains */
 652                                        pair_to_free = p;
 653                        }
 654
 655                        if (pair_to_free)
 656                                ;
 657                        else
 658                                diff_q(&outq, p);
 659                }
 660                else if (!diff_unmodified_pair(p))
 661                        /* all the usual ones need to be kept */
 662                        diff_q(&outq, p);
 663                else
 664                        /* no need to keep unmodified pairs */
 665                        pair_to_free = p;
 666
 667                if (pair_to_free)
 668                        diff_free_filepair(pair_to_free);
 669        }
 670        diff_debug_queue("done copying original", &outq);
 671
 672        free(q->queue);
 673        *q = outq;
 674        diff_debug_queue("done collapsing", q);
 675
 676        for (i = 0; i < rename_dst_nr; i++)
 677                free_filespec(rename_dst[i].two);
 678
 679        FREE_AND_NULL(rename_dst);
 680        rename_dst_nr = rename_dst_alloc = 0;
 681        FREE_AND_NULL(rename_src);
 682        rename_src_nr = rename_src_alloc = 0;
 683        return;
 684}