diffcore-rename.con commit rebase: fix documentation formatting (81d395c)
   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
  12static struct diff_rename_dst {
  13        struct diff_filespec *two;
  14        struct diff_filepair *pair;
  15} *rename_dst;
  16static int rename_dst_nr, rename_dst_alloc;
  17
  18static 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
  39static 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 */
  48static 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                MOVE_ARRAY(rename_dst + first + 1, rename_dst + first,
  61                           rename_dst_nr - first - 1);
  62        rename_dst[first].two = alloc_filespec(two->path);
  63        fill_filespec(rename_dst[first].two, &two->oid, two->oid_valid,
  64                      two->mode);
  65        rename_dst[first].pair = NULL;
  66        return 0;
  67}
  68
  69/* Table of rename/copy src files */
  70static struct diff_rename_src {
  71        struct diff_filepair *p;
  72        unsigned short score; /* to remember the break score */
  73} *rename_src;
  74static int rename_src_nr, rename_src_alloc;
  75
  76static struct diff_rename_src *register_rename_src(struct diff_filepair *p)
  77{
  78        int first, last;
  79        struct diff_filespec *one = p->one;
  80        unsigned short score = p->score;
  81
  82        first = 0;
  83        last = rename_src_nr;
  84        while (last > first) {
  85                int next = (last + first) >> 1;
  86                struct diff_rename_src *src = &(rename_src[next]);
  87                int cmp = strcmp(one->path, src->p->one->path);
  88                if (!cmp)
  89                        return src;
  90                if (cmp < 0) {
  91                        last = next;
  92                        continue;
  93                }
  94                first = next+1;
  95        }
  96
  97        /* insert to make it at "first" */
  98        ALLOC_GROW(rename_src, rename_src_nr + 1, rename_src_alloc);
  99        rename_src_nr++;
 100        if (first < rename_src_nr)
 101                MOVE_ARRAY(rename_src + first + 1, rename_src + first,
 102                           rename_src_nr - first - 1);
 103        rename_src[first].p = p;
 104        rename_src[first].score = score;
 105        return &(rename_src[first]);
 106}
 107
 108static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
 109{
 110        int src_len = strlen(src->path), dst_len = strlen(dst->path);
 111        while (src_len && dst_len) {
 112                char c1 = src->path[--src_len];
 113                char c2 = dst->path[--dst_len];
 114                if (c1 != c2)
 115                        return 0;
 116                if (c1 == '/')
 117                        return 1;
 118        }
 119        return (!src_len || src->path[src_len - 1] == '/') &&
 120                (!dst_len || dst->path[dst_len - 1] == '/');
 121}
 122
 123struct diff_score {
 124        int src; /* index in rename_src */
 125        int dst; /* index in rename_dst */
 126        unsigned short score;
 127        short name_score;
 128};
 129
 130static int estimate_similarity(struct diff_filespec *src,
 131                               struct diff_filespec *dst,
 132                               int minimum_score)
 133{
 134        /* src points at a file that existed in the original tree (or
 135         * optionally a file in the destination tree) and dst points
 136         * at a newly created file.  They may be quite similar, in which
 137         * case we want to say src is renamed to dst or src is copied into
 138         * dst, and then some edit has been applied to dst.
 139         *
 140         * Compare them and return how similar they are, representing
 141         * the score as an integer between 0 and MAX_SCORE.
 142         *
 143         * When there is an exact match, it is considered a better
 144         * match than anything else; the destination does not even
 145         * call into this function in that case.
 146         */
 147        unsigned long max_size, delta_size, base_size, src_copied, literal_added;
 148        int score;
 149
 150        /* We deal only with regular files.  Symlink renames are handled
 151         * only when they are exact matches --- in other words, no edits
 152         * after renaming.
 153         */
 154        if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
 155                return 0;
 156
 157        /*
 158         * Need to check that source and destination sizes are
 159         * filled in before comparing them.
 160         *
 161         * If we already have "cnt_data" filled in, we know it's
 162         * all good (avoid checking the size for zero, as that
 163         * is a possible size - we really should have a flag to
 164         * say whether the size is valid or not!)
 165         */
 166        if (!src->cnt_data &&
 167            diff_populate_filespec(src, CHECK_SIZE_ONLY))
 168                return 0;
 169        if (!dst->cnt_data &&
 170            diff_populate_filespec(dst, CHECK_SIZE_ONLY))
 171                return 0;
 172
 173        max_size = ((src->size > dst->size) ? src->size : dst->size);
 174        base_size = ((src->size < dst->size) ? src->size : dst->size);
 175        delta_size = max_size - base_size;
 176
 177        /* We would not consider edits that change the file size so
 178         * drastically.  delta_size must be smaller than
 179         * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
 180         *
 181         * Note that base_size == 0 case is handled here already
 182         * and the final score computation below would not have a
 183         * divide-by-zero issue.
 184         */
 185        if (max_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
 186                return 0;
 187
 188        if (!src->cnt_data && diff_populate_filespec(src, 0))
 189                return 0;
 190        if (!dst->cnt_data && diff_populate_filespec(dst, 0))
 191                return 0;
 192
 193        if (diffcore_count_changes(src, dst,
 194                                   &src->cnt_data, &dst->cnt_data,
 195                                   &src_copied, &literal_added))
 196                return 0;
 197
 198        /* How similar are they?
 199         * what percentage of material in dst are from source?
 200         */
 201        if (!dst->size)
 202                score = 0; /* should not happen */
 203        else
 204                score = (int)(src_copied * MAX_SCORE / max_size);
 205        return score;
 206}
 207
 208static void record_rename_pair(int dst_index, int src_index, int score)
 209{
 210        struct diff_filespec *src, *dst;
 211        struct diff_filepair *dp;
 212
 213        if (rename_dst[dst_index].pair)
 214                die("internal error: dst already matched.");
 215
 216        src = rename_src[src_index].p->one;
 217        src->rename_used++;
 218        src->count++;
 219
 220        dst = rename_dst[dst_index].two;
 221        dst->count++;
 222
 223        dp = diff_queue(NULL, src, dst);
 224        dp->renamed_pair = 1;
 225        if (!strcmp(src->path, dst->path))
 226                dp->score = rename_src[src_index].score;
 227        else
 228                dp->score = score;
 229        rename_dst[dst_index].pair = dp;
 230}
 231
 232/*
 233 * We sort the rename similarity matrix with the score, in descending
 234 * order (the most similar first).
 235 */
 236static int score_compare(const void *a_, const void *b_)
 237{
 238        const struct diff_score *a = a_, *b = b_;
 239
 240        /* sink the unused ones to the bottom */
 241        if (a->dst < 0)
 242                return (0 <= b->dst);
 243        else if (b->dst < 0)
 244                return -1;
 245
 246        if (a->score == b->score)
 247                return b->name_score - a->name_score;
 248
 249        return b->score - a->score;
 250}
 251
 252struct file_similarity {
 253        struct hashmap_entry entry;
 254        int index;
 255        struct diff_filespec *filespec;
 256};
 257
 258static unsigned int hash_filespec(struct diff_filespec *filespec)
 259{
 260        if (!filespec->oid_valid) {
 261                if (diff_populate_filespec(filespec, 0))
 262                        return 0;
 263                hash_object_file(filespec->data, filespec->size, "blob",
 264                                 &filespec->oid);
 265        }
 266        return sha1hash(filespec->oid.hash);
 267}
 268
 269static int find_identical_files(struct hashmap *srcs,
 270                                int dst_index,
 271                                struct diff_options *options)
 272{
 273        int renames = 0;
 274
 275        struct diff_filespec *target = rename_dst[dst_index].two;
 276        struct file_similarity *p, *best = NULL;
 277        int i = 100, best_score = -1;
 278
 279        /*
 280         * Find the best source match for specified destination.
 281         */
 282        p = hashmap_get_from_hash(srcs, hash_filespec(target), NULL);
 283        for (; p; p = hashmap_get_next(srcs, p)) {
 284                int score;
 285                struct diff_filespec *source = p->filespec;
 286
 287                /* False hash collision? */
 288                if (oidcmp(&source->oid, &target->oid))
 289                        continue;
 290                /* Non-regular files? If so, the modes must match! */
 291                if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
 292                        if (source->mode != target->mode)
 293                                continue;
 294                }
 295                /* Give higher scores to sources that haven't been used already */
 296                score = !source->rename_used;
 297                if (source->rename_used && options->detect_rename != DIFF_DETECT_COPY)
 298                        continue;
 299                score += basename_same(source, target);
 300                if (score > best_score) {
 301                        best = p;
 302                        best_score = score;
 303                        if (score == 2)
 304                                break;
 305                }
 306
 307                /* Too many identical alternatives? Pick one */
 308                if (!--i)
 309                        break;
 310        }
 311        if (best) {
 312                record_rename_pair(dst_index, best->index, MAX_SCORE);
 313                renames++;
 314        }
 315        return renames;
 316}
 317
 318static void insert_file_table(struct hashmap *table, int index, struct diff_filespec *filespec)
 319{
 320        struct file_similarity *entry = xmalloc(sizeof(*entry));
 321
 322        entry->index = index;
 323        entry->filespec = filespec;
 324
 325        hashmap_entry_init(entry, hash_filespec(filespec));
 326        hashmap_add(table, entry);
 327}
 328
 329/*
 330 * Find exact renames first.
 331 *
 332 * The first round matches up the up-to-date entries,
 333 * and then during the second round we try to match
 334 * cache-dirty entries as well.
 335 */
 336static int find_exact_renames(struct diff_options *options)
 337{
 338        int i, renames = 0;
 339        struct hashmap file_table;
 340
 341        /* Add all sources to the hash table in reverse order, because
 342         * later on they will be retrieved in LIFO order.
 343         */
 344        hashmap_init(&file_table, NULL, NULL, rename_src_nr);
 345        for (i = rename_src_nr-1; i >= 0; i--)
 346                insert_file_table(&file_table, i, rename_src[i].p->one);
 347
 348        /* Walk the destinations and find best source match */
 349        for (i = 0; i < rename_dst_nr; i++)
 350                renames += find_identical_files(&file_table, i, options);
 351
 352        /* Free the hash data structure and entries */
 353        hashmap_free(&file_table, 1);
 354
 355        return renames;
 356}
 357
 358#define NUM_CANDIDATE_PER_DST 4
 359static void record_if_better(struct diff_score m[], struct diff_score *o)
 360{
 361        int i, worst;
 362
 363        /* find the worst one */
 364        worst = 0;
 365        for (i = 1; i < NUM_CANDIDATE_PER_DST; i++)
 366                if (score_compare(&m[i], &m[worst]) > 0)
 367                        worst = i;
 368
 369        /* is it better than the worst one? */
 370        if (score_compare(&m[worst], o) > 0)
 371                m[worst] = *o;
 372}
 373
 374/*
 375 * Returns:
 376 * 0 if we are under the limit;
 377 * 1 if we need to disable inexact rename detection;
 378 * 2 if we would be under the limit if we were given -C instead of -C -C.
 379 */
 380static int too_many_rename_candidates(int num_create,
 381                                      struct diff_options *options)
 382{
 383        int rename_limit = options->rename_limit;
 384        int num_src = rename_src_nr;
 385        int i;
 386
 387        options->needed_rename_limit = 0;
 388
 389        /*
 390         * This basically does a test for the rename matrix not
 391         * growing larger than a "rename_limit" square matrix, ie:
 392         *
 393         *    num_create * num_src > rename_limit * rename_limit
 394         */
 395        if (rename_limit <= 0)
 396                rename_limit = 32767;
 397        if ((num_create <= rename_limit || num_src <= rename_limit) &&
 398            ((uint64_t)num_create * (uint64_t)num_src
 399             <= (uint64_t)rename_limit * (uint64_t)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 (!options->flags.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            ((uint64_t)num_create * (uint64_t)num_src
 417             <= (uint64_t)rename_limit * (uint64_t)rename_limit))
 418                return 2;
 419        return 1;
 420}
 421
 422static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, int copies)
 423{
 424        int count = 0, i;
 425
 426        for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
 427                struct diff_rename_dst *dst;
 428
 429                if ((mx[i].dst < 0) ||
 430                    (mx[i].score < minimum_score))
 431                        break; /* there is no more usable pair. */
 432                dst = &rename_dst[mx[i].dst];
 433                if (dst->pair)
 434                        continue; /* already done, either exact or fuzzy. */
 435                if (!copies && rename_src[mx[i].src].p->one->rename_used)
 436                        continue;
 437                record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
 438                count++;
 439        }
 440        return count;
 441}
 442
 443void diffcore_rename(struct diff_options *options)
 444{
 445        int detect_rename = options->detect_rename;
 446        int minimum_score = options->rename_score;
 447        struct diff_queue_struct *q = &diff_queued_diff;
 448        struct diff_queue_struct outq;
 449        struct diff_score *mx;
 450        int i, j, rename_count, skip_unmodified = 0;
 451        int num_create, dst_cnt;
 452        struct progress *progress = NULL;
 453
 454        if (!minimum_score)
 455                minimum_score = DEFAULT_RENAME_SCORE;
 456
 457        for (i = 0; i < q->nr; i++) {
 458                struct diff_filepair *p = q->queue[i];
 459                if (!DIFF_FILE_VALID(p->one)) {
 460                        if (!DIFF_FILE_VALID(p->two))
 461                                continue; /* unmerged */
 462                        else if (options->single_follow &&
 463                                 strcmp(options->single_follow, p->two->path))
 464                                continue; /* not interested */
 465                        else if (!options->flags.rename_empty &&
 466                                 is_empty_blob_oid(&p->two->oid))
 467                                continue;
 468                        else if (add_rename_dst(p->two) < 0) {
 469                                warning("skipping rename detection, detected"
 470                                        " duplicate destination '%s'",
 471                                        p->two->path);
 472                                goto cleanup;
 473                        }
 474                }
 475                else if (!options->flags.rename_empty &&
 476                         is_empty_blob_oid(&p->one->oid))
 477                        continue;
 478                else if (!DIFF_PAIR_UNMERGED(p) && !DIFF_FILE_VALID(p->two)) {
 479                        /*
 480                         * If the source is a broken "delete", and
 481                         * they did not really want to get broken,
 482                         * that means the source actually stays.
 483                         * So we increment the "rename_used" score
 484                         * by one, to indicate ourselves as a user
 485                         */
 486                        if (p->broken_pair && !p->score)
 487                                p->one->rename_used++;
 488                        register_rename_src(p);
 489                }
 490                else if (detect_rename == DIFF_DETECT_COPY) {
 491                        /*
 492                         * Increment the "rename_used" score by
 493                         * one, to indicate ourselves as a user.
 494                         */
 495                        p->one->rename_used++;
 496                        register_rename_src(p);
 497                }
 498        }
 499        if (rename_dst_nr == 0 || rename_src_nr == 0)
 500                goto cleanup; /* nothing to do */
 501
 502        /*
 503         * We really want to cull the candidates list early
 504         * with cheap tests in order to avoid doing deltas.
 505         */
 506        rename_count = find_exact_renames(options);
 507
 508        /* Did we only want exact renames? */
 509        if (minimum_score == MAX_SCORE)
 510                goto cleanup;
 511
 512        /*
 513         * Calculate how many renames are left (but all the source
 514         * files still remain as options for rename/copies!)
 515         */
 516        num_create = (rename_dst_nr - rename_count);
 517
 518        /* All done? */
 519        if (!num_create)
 520                goto cleanup;
 521
 522        switch (too_many_rename_candidates(num_create, options)) {
 523        case 1:
 524                goto cleanup;
 525        case 2:
 526                options->degraded_cc_to_c = 1;
 527                skip_unmodified = 1;
 528                break;
 529        default:
 530                break;
 531        }
 532
 533        if (options->show_rename_progress) {
 534                progress = start_delayed_progress(
 535                                _("Performing inexact rename detection"),
 536                                (uint64_t)rename_dst_nr * (uint64_t)rename_src_nr);
 537        }
 538
 539        mx = xcalloc(st_mult(NUM_CANDIDATE_PER_DST, num_create), sizeof(*mx));
 540        for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
 541                struct diff_filespec *two = rename_dst[i].two;
 542                struct diff_score *m;
 543
 544                if (rename_dst[i].pair)
 545                        continue; /* dealt with exact match already. */
 546
 547                m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST];
 548                for (j = 0; j < NUM_CANDIDATE_PER_DST; j++)
 549                        m[j].dst = -1;
 550
 551                for (j = 0; j < rename_src_nr; j++) {
 552                        struct diff_filespec *one = rename_src[j].p->one;
 553                        struct diff_score this_src;
 554
 555                        if (skip_unmodified &&
 556                            diff_unmodified_pair(rename_src[j].p))
 557                                continue;
 558
 559                        this_src.score = estimate_similarity(one, two,
 560                                                             minimum_score);
 561                        this_src.name_score = basename_same(one, two);
 562                        this_src.dst = i;
 563                        this_src.src = j;
 564                        record_if_better(m, &this_src);
 565                        /*
 566                         * Once we run estimate_similarity,
 567                         * We do not need the text anymore.
 568                         */
 569                        diff_free_filespec_blob(one);
 570                        diff_free_filespec_blob(two);
 571                }
 572                dst_cnt++;
 573                display_progress(progress, (uint64_t)(i+1)*(uint64_t)rename_src_nr);
 574        }
 575        stop_progress(&progress);
 576
 577        /* cost matrix sorted by most to least similar pair */
 578        QSORT(mx, dst_cnt * NUM_CANDIDATE_PER_DST, score_compare);
 579
 580        rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
 581        if (detect_rename == DIFF_DETECT_COPY)
 582                rename_count += find_renames(mx, dst_cnt, minimum_score, 1);
 583        free(mx);
 584
 585 cleanup:
 586        /* At this point, we have found some renames and copies and they
 587         * are recorded in rename_dst.  The original list is still in *q.
 588         */
 589        DIFF_QUEUE_CLEAR(&outq);
 590        for (i = 0; i < q->nr; i++) {
 591                struct diff_filepair *p = q->queue[i];
 592                struct diff_filepair *pair_to_free = NULL;
 593
 594                if (DIFF_PAIR_UNMERGED(p)) {
 595                        diff_q(&outq, p);
 596                }
 597                else if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
 598                        /*
 599                         * Creation
 600                         *
 601                         * We would output this create record if it has
 602                         * not been turned into a rename/copy already.
 603                         */
 604                        struct diff_rename_dst *dst = locate_rename_dst(p->two);
 605                        if (dst && dst->pair) {
 606                                diff_q(&outq, dst->pair);
 607                                pair_to_free = p;
 608                        }
 609                        else
 610                                /* no matching rename/copy source, so
 611                                 * record this as a creation.
 612                                 */
 613                                diff_q(&outq, p);
 614                }
 615                else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
 616                        /*
 617                         * Deletion
 618                         *
 619                         * We would output this delete record if:
 620                         *
 621                         * (1) this is a broken delete and the counterpart
 622                         *     broken create remains in the output; or
 623                         * (2) this is not a broken delete, and rename_dst
 624                         *     does not have a rename/copy to move p->one->path
 625                         *     out of existence.
 626                         *
 627                         * Otherwise, the counterpart broken create
 628                         * has been turned into a rename-edit; or
 629                         * delete did not have a matching create to
 630                         * begin with.
 631                         */
 632                        if (DIFF_PAIR_BROKEN(p)) {
 633                                /* broken delete */
 634                                struct diff_rename_dst *dst = locate_rename_dst(p->one);
 635                                if (dst && dst->pair)
 636                                        /* counterpart is now rename/copy */
 637                                        pair_to_free = p;
 638                        }
 639                        else {
 640                                if (p->one->rename_used)
 641                                        /* this path remains */
 642                                        pair_to_free = p;
 643                        }
 644
 645                        if (pair_to_free)
 646                                ;
 647                        else
 648                                diff_q(&outq, p);
 649                }
 650                else if (!diff_unmodified_pair(p))
 651                        /* all the usual ones need to be kept */
 652                        diff_q(&outq, p);
 653                else
 654                        /* no need to keep unmodified pairs */
 655                        pair_to_free = p;
 656
 657                if (pair_to_free)
 658                        diff_free_filepair(pair_to_free);
 659        }
 660        diff_debug_queue("done copying original", &outq);
 661
 662        free(q->queue);
 663        *q = outq;
 664        diff_debug_queue("done collapsing", q);
 665
 666        for (i = 0; i < rename_dst_nr; i++)
 667                free_filespec(rename_dst[i].two);
 668
 669        FREE_AND_NULL(rename_dst);
 670        rename_dst_nr = rename_dst_alloc = 0;
 671        FREE_AND_NULL(rename_src);
 672        rename_src_nr = rename_src_alloc = 0;
 673        return;
 674}