diffcore-rename.con commit diff-lib: allow ita entries treated as "not yet exist in index" (425a28e)
   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                memmove(rename_dst + first + 1, rename_dst + first,
  61                        (rename_dst_nr - first - 1) * sizeof(*rename_dst));
  62        rename_dst[first].two = alloc_filespec(two->path);
  63        fill_filespec(rename_dst[first].two, two->oid.hash, 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                memmove(rename_src + first + 1, rename_src + first,
 102                        (rename_src_nr - first - 1) * sizeof(*rename_src));
 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        unsigned long delta_limit;
 149        int score;
 150
 151        /* We deal only with regular files.  Symlink renames are handled
 152         * only when they are exact matches --- in other words, no edits
 153         * after renaming.
 154         */
 155        if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
 156                return 0;
 157
 158        /*
 159         * Need to check that source and destination sizes are
 160         * filled in before comparing them.
 161         *
 162         * If we already have "cnt_data" filled in, we know it's
 163         * all good (avoid checking the size for zero, as that
 164         * is a possible size - we really should have a flag to
 165         * say whether the size is valid or not!)
 166         */
 167        if (!src->cnt_data &&
 168            diff_populate_filespec(src, CHECK_SIZE_ONLY))
 169                return 0;
 170        if (!dst->cnt_data &&
 171            diff_populate_filespec(dst, CHECK_SIZE_ONLY))
 172                return 0;
 173
 174        max_size = ((src->size > dst->size) ? src->size : dst->size);
 175        base_size = ((src->size < dst->size) ? src->size : dst->size);
 176        delta_size = max_size - base_size;
 177
 178        /* We would not consider edits that change the file size so
 179         * drastically.  delta_size must be smaller than
 180         * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
 181         *
 182         * Note that base_size == 0 case is handled here already
 183         * and the final score computation below would not have a
 184         * divide-by-zero issue.
 185         */
 186        if (max_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
 187                return 0;
 188
 189        if (!src->cnt_data && diff_populate_filespec(src, 0))
 190                return 0;
 191        if (!dst->cnt_data && diff_populate_filespec(dst, 0))
 192                return 0;
 193
 194        delta_limit = (unsigned long)
 195                (base_size * (MAX_SCORE-minimum_score) / MAX_SCORE);
 196        if (diffcore_count_changes(src, dst,
 197                                   &src->cnt_data, &dst->cnt_data,
 198                                   delta_limit,
 199                                   &src_copied, &literal_added))
 200                return 0;
 201
 202        /* How similar are they?
 203         * what percentage of material in dst are from source?
 204         */
 205        if (!dst->size)
 206                score = 0; /* should not happen */
 207        else
 208                score = (int)(src_copied * MAX_SCORE / max_size);
 209        return score;
 210}
 211
 212static void record_rename_pair(int dst_index, int src_index, int score)
 213{
 214        struct diff_filespec *src, *dst;
 215        struct diff_filepair *dp;
 216
 217        if (rename_dst[dst_index].pair)
 218                die("internal error: dst already matched.");
 219
 220        src = rename_src[src_index].p->one;
 221        src->rename_used++;
 222        src->count++;
 223
 224        dst = rename_dst[dst_index].two;
 225        dst->count++;
 226
 227        dp = diff_queue(NULL, src, dst);
 228        dp->renamed_pair = 1;
 229        if (!strcmp(src->path, dst->path))
 230                dp->score = rename_src[src_index].score;
 231        else
 232                dp->score = score;
 233        rename_dst[dst_index].pair = dp;
 234}
 235
 236/*
 237 * We sort the rename similarity matrix with the score, in descending
 238 * order (the most similar first).
 239 */
 240static int score_compare(const void *a_, const void *b_)
 241{
 242        const struct diff_score *a = a_, *b = b_;
 243
 244        /* sink the unused ones to the bottom */
 245        if (a->dst < 0)
 246                return (0 <= b->dst);
 247        else if (b->dst < 0)
 248                return -1;
 249
 250        if (a->score == b->score)
 251                return b->name_score - a->name_score;
 252
 253        return b->score - a->score;
 254}
 255
 256struct file_similarity {
 257        struct hashmap_entry entry;
 258        int index;
 259        struct diff_filespec *filespec;
 260};
 261
 262static unsigned int hash_filespec(struct diff_filespec *filespec)
 263{
 264        if (!filespec->oid_valid) {
 265                if (diff_populate_filespec(filespec, 0))
 266                        return 0;
 267                hash_sha1_file(filespec->data, filespec->size, "blob",
 268                               filespec->oid.hash);
 269        }
 270        return sha1hash(filespec->oid.hash);
 271}
 272
 273static int find_identical_files(struct hashmap *srcs,
 274                                int dst_index,
 275                                struct diff_options *options)
 276{
 277        int renames = 0;
 278
 279        struct diff_filespec *target = rename_dst[dst_index].two;
 280        struct file_similarity *p, *best = NULL;
 281        int i = 100, best_score = -1;
 282
 283        /*
 284         * Find the best source match for specified destination.
 285         */
 286        p = hashmap_get_from_hash(srcs, hash_filespec(target), NULL);
 287        for (; p; p = hashmap_get_next(srcs, p)) {
 288                int score;
 289                struct diff_filespec *source = p->filespec;
 290
 291                /* False hash collision? */
 292                if (oidcmp(&source->oid, &target->oid))
 293                        continue;
 294                /* Non-regular files? If so, the modes must match! */
 295                if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
 296                        if (source->mode != target->mode)
 297                                continue;
 298                }
 299                /* Give higher scores to sources that haven't been used already */
 300                score = !source->rename_used;
 301                if (source->rename_used && options->detect_rename != DIFF_DETECT_COPY)
 302                        continue;
 303                score += basename_same(source, target);
 304                if (score > best_score) {
 305                        best = p;
 306                        best_score = score;
 307                        if (score == 2)
 308                                break;
 309                }
 310
 311                /* Too many identical alternatives? Pick one */
 312                if (!--i)
 313                        break;
 314        }
 315        if (best) {
 316                record_rename_pair(dst_index, best->index, MAX_SCORE);
 317                renames++;
 318        }
 319        return renames;
 320}
 321
 322static void insert_file_table(struct hashmap *table, int index, struct diff_filespec *filespec)
 323{
 324        struct file_similarity *entry = xmalloc(sizeof(*entry));
 325
 326        entry->index = index;
 327        entry->filespec = filespec;
 328
 329        hashmap_entry_init(entry, hash_filespec(filespec));
 330        hashmap_add(table, entry);
 331}
 332
 333/*
 334 * Find exact renames first.
 335 *
 336 * The first round matches up the up-to-date entries,
 337 * and then during the second round we try to match
 338 * cache-dirty entries as well.
 339 */
 340static int find_exact_renames(struct diff_options *options)
 341{
 342        int i, renames = 0;
 343        struct hashmap file_table;
 344
 345        /* Add all sources to the hash table in reverse order, because
 346         * later on they will be retrieved in LIFO order.
 347         */
 348        hashmap_init(&file_table, NULL, rename_src_nr);
 349        for (i = rename_src_nr-1; i >= 0; i--)
 350                insert_file_table(&file_table, i, rename_src[i].p->one);
 351
 352        /* Walk the destinations and find best source match */
 353        for (i = 0; i < rename_dst_nr; i++)
 354                renames += find_identical_files(&file_table, i, options);
 355
 356        /* Free the hash data structure and entries */
 357        hashmap_free(&file_table, 1);
 358
 359        return renames;
 360}
 361
 362#define NUM_CANDIDATE_PER_DST 4
 363static void record_if_better(struct diff_score m[], struct diff_score *o)
 364{
 365        int i, worst;
 366
 367        /* find the worst one */
 368        worst = 0;
 369        for (i = 1; i < NUM_CANDIDATE_PER_DST; i++)
 370                if (score_compare(&m[i], &m[worst]) > 0)
 371                        worst = i;
 372
 373        /* is it better than the worst one? */
 374        if (score_compare(&m[worst], o) > 0)
 375                m[worst] = *o;
 376}
 377
 378/*
 379 * Returns:
 380 * 0 if we are under the limit;
 381 * 1 if we need to disable inexact rename detection;
 382 * 2 if we would be under the limit if we were given -C instead of -C -C.
 383 */
 384static int too_many_rename_candidates(int num_create,
 385                                      struct diff_options *options)
 386{
 387        int rename_limit = options->rename_limit;
 388        int num_src = rename_src_nr;
 389        int i;
 390
 391        options->needed_rename_limit = 0;
 392
 393        /*
 394         * This basically does a test for the rename matrix not
 395         * growing larger than a "rename_limit" square matrix, ie:
 396         *
 397         *    num_create * num_src > rename_limit * rename_limit
 398         *
 399         * but handles the potential overflow case specially (and we
 400         * assume at least 32-bit integers)
 401         */
 402        if (rename_limit <= 0 || rename_limit > 32767)
 403                rename_limit = 32767;
 404        if ((num_create <= rename_limit || num_src <= rename_limit) &&
 405            (num_create * num_src <= rename_limit * rename_limit))
 406                return 0;
 407
 408        options->needed_rename_limit =
 409                num_src > num_create ? num_src : num_create;
 410
 411        /* Are we running under -C -C? */
 412        if (!DIFF_OPT_TST(options, FIND_COPIES_HARDER))
 413                return 1;
 414
 415        /* Would we bust the limit if we were running under -C? */
 416        for (num_src = i = 0; i < rename_src_nr; i++) {
 417                if (diff_unmodified_pair(rename_src[i].p))
 418                        continue;
 419                num_src++;
 420        }
 421        if ((num_create <= rename_limit || num_src <= rename_limit) &&
 422            (num_create * num_src <= rename_limit * rename_limit))
 423                return 2;
 424        return 1;
 425}
 426
 427static int find_renames(struct diff_score *mx, int dst_cnt, int minimum_score, int copies)
 428{
 429        int count = 0, i;
 430
 431        for (i = 0; i < dst_cnt * NUM_CANDIDATE_PER_DST; i++) {
 432                struct diff_rename_dst *dst;
 433
 434                if ((mx[i].dst < 0) ||
 435                    (mx[i].score < minimum_score))
 436                        break; /* there is no more usable pair. */
 437                dst = &rename_dst[mx[i].dst];
 438                if (dst->pair)
 439                        continue; /* already done, either exact or fuzzy. */
 440                if (!copies && rename_src[mx[i].src].p->one->rename_used)
 441                        continue;
 442                record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
 443                count++;
 444        }
 445        return count;
 446}
 447
 448void diffcore_rename(struct diff_options *options)
 449{
 450        int detect_rename = options->detect_rename;
 451        int minimum_score = options->rename_score;
 452        struct diff_queue_struct *q = &diff_queued_diff;
 453        struct diff_queue_struct outq;
 454        struct diff_score *mx;
 455        int i, j, rename_count, skip_unmodified = 0;
 456        int num_create, dst_cnt;
 457        struct progress *progress = NULL;
 458
 459        if (!minimum_score)
 460                minimum_score = DEFAULT_RENAME_SCORE;
 461
 462        for (i = 0; i < q->nr; i++) {
 463                struct diff_filepair *p = q->queue[i];
 464                if (!DIFF_FILE_VALID(p->one)) {
 465                        if (!DIFF_FILE_VALID(p->two))
 466                                continue; /* unmerged */
 467                        else if (options->single_follow &&
 468                                 strcmp(options->single_follow, p->two->path))
 469                                continue; /* not interested */
 470                        else if (!DIFF_OPT_TST(options, RENAME_EMPTY) &&
 471                                 is_empty_blob_sha1(p->two->oid.hash))
 472                                continue;
 473                        else if (add_rename_dst(p->two) < 0) {
 474                                warning("skipping rename detection, detected"
 475                                        " duplicate destination '%s'",
 476                                        p->two->path);
 477                                goto cleanup;
 478                        }
 479                }
 480                else if (!DIFF_OPT_TST(options, RENAME_EMPTY) &&
 481                         is_empty_blob_sha1(p->one->oid.hash))
 482                        continue;
 483                else if (!DIFF_PAIR_UNMERGED(p) && !DIFF_FILE_VALID(p->two)) {
 484                        /*
 485                         * If the source is a broken "delete", and
 486                         * they did not really want to get broken,
 487                         * that means the source actually stays.
 488                         * So we increment the "rename_used" score
 489                         * by one, to indicate ourselves as a user
 490                         */
 491                        if (p->broken_pair && !p->score)
 492                                p->one->rename_used++;
 493                        register_rename_src(p);
 494                }
 495                else if (detect_rename == DIFF_DETECT_COPY) {
 496                        /*
 497                         * Increment the "rename_used" score by
 498                         * one, to indicate ourselves as a user.
 499                         */
 500                        p->one->rename_used++;
 501                        register_rename_src(p);
 502                }
 503        }
 504        if (rename_dst_nr == 0 || rename_src_nr == 0)
 505                goto cleanup; /* nothing to do */
 506
 507        /*
 508         * We really want to cull the candidates list early
 509         * with cheap tests in order to avoid doing deltas.
 510         */
 511        rename_count = find_exact_renames(options);
 512
 513        /* Did we only want exact renames? */
 514        if (minimum_score == MAX_SCORE)
 515                goto cleanup;
 516
 517        /*
 518         * Calculate how many renames are left (but all the source
 519         * files still remain as options for rename/copies!)
 520         */
 521        num_create = (rename_dst_nr - rename_count);
 522
 523        /* All done? */
 524        if (!num_create)
 525                goto cleanup;
 526
 527        switch (too_many_rename_candidates(num_create, options)) {
 528        case 1:
 529                goto cleanup;
 530        case 2:
 531                options->degraded_cc_to_c = 1;
 532                skip_unmodified = 1;
 533                break;
 534        default:
 535                break;
 536        }
 537
 538        if (options->show_rename_progress) {
 539                progress = start_progress_delay(
 540                                _("Performing inexact rename detection"),
 541                                rename_dst_nr * rename_src_nr, 50, 1);
 542        }
 543
 544        mx = xcalloc(st_mult(NUM_CANDIDATE_PER_DST, num_create), sizeof(*mx));
 545        for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
 546                struct diff_filespec *two = rename_dst[i].two;
 547                struct diff_score *m;
 548
 549                if (rename_dst[i].pair)
 550                        continue; /* dealt with exact match already. */
 551
 552                m = &mx[dst_cnt * NUM_CANDIDATE_PER_DST];
 553                for (j = 0; j < NUM_CANDIDATE_PER_DST; j++)
 554                        m[j].dst = -1;
 555
 556                for (j = 0; j < rename_src_nr; j++) {
 557                        struct diff_filespec *one = rename_src[j].p->one;
 558                        struct diff_score this_src;
 559
 560                        if (skip_unmodified &&
 561                            diff_unmodified_pair(rename_src[j].p))
 562                                continue;
 563
 564                        this_src.score = estimate_similarity(one, two,
 565                                                             minimum_score);
 566                        this_src.name_score = basename_same(one, two);
 567                        this_src.dst = i;
 568                        this_src.src = j;
 569                        record_if_better(m, &this_src);
 570                        /*
 571                         * Once we run estimate_similarity,
 572                         * We do not need the text anymore.
 573                         */
 574                        diff_free_filespec_blob(one);
 575                        diff_free_filespec_blob(two);
 576                }
 577                dst_cnt++;
 578                display_progress(progress, (i+1)*rename_src_nr);
 579        }
 580        stop_progress(&progress);
 581
 582        /* cost matrix sorted by most to least similar pair */
 583        qsort(mx, dst_cnt * NUM_CANDIDATE_PER_DST, sizeof(*mx), score_compare);
 584
 585        rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
 586        if (detect_rename == DIFF_DETECT_COPY)
 587                rename_count += find_renames(mx, dst_cnt, minimum_score, 1);
 588        free(mx);
 589
 590 cleanup:
 591        /* At this point, we have found some renames and copies and they
 592         * are recorded in rename_dst.  The original list is still in *q.
 593         */
 594        DIFF_QUEUE_CLEAR(&outq);
 595        for (i = 0; i < q->nr; i++) {
 596                struct diff_filepair *p = q->queue[i];
 597                struct diff_filepair *pair_to_free = NULL;
 598
 599                if (DIFF_PAIR_UNMERGED(p)) {
 600                        diff_q(&outq, p);
 601                }
 602                else if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
 603                        /*
 604                         * Creation
 605                         *
 606                         * We would output this create record if it has
 607                         * not been turned into a rename/copy already.
 608                         */
 609                        struct diff_rename_dst *dst = locate_rename_dst(p->two);
 610                        if (dst && dst->pair) {
 611                                diff_q(&outq, dst->pair);
 612                                pair_to_free = p;
 613                        }
 614                        else
 615                                /* no matching rename/copy source, so
 616                                 * record this as a creation.
 617                                 */
 618                                diff_q(&outq, p);
 619                }
 620                else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
 621                        /*
 622                         * Deletion
 623                         *
 624                         * We would output this delete record if:
 625                         *
 626                         * (1) this is a broken delete and the counterpart
 627                         *     broken create remains in the output; or
 628                         * (2) this is not a broken delete, and rename_dst
 629                         *     does not have a rename/copy to move p->one->path
 630                         *     out of existence.
 631                         *
 632                         * Otherwise, the counterpart broken create
 633                         * has been turned into a rename-edit; or
 634                         * delete did not have a matching create to
 635                         * begin with.
 636                         */
 637                        if (DIFF_PAIR_BROKEN(p)) {
 638                                /* broken delete */
 639                                struct diff_rename_dst *dst = locate_rename_dst(p->one);
 640                                if (dst && dst->pair)
 641                                        /* counterpart is now rename/copy */
 642                                        pair_to_free = p;
 643                        }
 644                        else {
 645                                if (p->one->rename_used)
 646                                        /* this path remains */
 647                                        pair_to_free = p;
 648                        }
 649
 650                        if (pair_to_free)
 651                                ;
 652                        else
 653                                diff_q(&outq, p);
 654                }
 655                else if (!diff_unmodified_pair(p))
 656                        /* all the usual ones need to be kept */
 657                        diff_q(&outq, p);
 658                else
 659                        /* no need to keep unmodified pairs */
 660                        pair_to_free = p;
 661
 662                if (pair_to_free)
 663                        diff_free_filepair(pair_to_free);
 664        }
 665        diff_debug_queue("done copying original", &outq);
 666
 667        free(q->queue);
 668        *q = outq;
 669        diff_debug_queue("done collapsing", q);
 670
 671        for (i = 0; i < rename_dst_nr; i++)
 672                free_filespec(rename_dst[i].two);
 673
 674        free(rename_dst);
 675        rename_dst = NULL;
 676        rename_dst_nr = rename_dst_alloc = 0;
 677        free(rename_src);
 678        rename_src = NULL;
 679        rename_src_nr = rename_src_alloc = 0;
 680        return;
 681}