diffcore-rename.con commit Documentation/technical/api-diff.txt: correct name of diff_unmerge() (7a45c31)
   1/*
   2 * Copyright (C) 2005 Junio C Hamano
   3 */
   4#include "cache.h"
   5#include "diff.h"
   6#include "diffcore.h"
   7#include "hash.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 struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
  19                                                 int insert_ok)
  20{
  21        int first, last;
  22
  23        first = 0;
  24        last = rename_dst_nr;
  25        while (last > first) {
  26                int next = (last + first) >> 1;
  27                struct diff_rename_dst *dst = &(rename_dst[next]);
  28                int cmp = strcmp(two->path, dst->two->path);
  29                if (!cmp)
  30                        return dst;
  31                if (cmp < 0) {
  32                        last = next;
  33                        continue;
  34                }
  35                first = next+1;
  36        }
  37        /* not found */
  38        if (!insert_ok)
  39                return NULL;
  40        /* insert to make it at "first" */
  41        if (rename_dst_alloc <= rename_dst_nr) {
  42                rename_dst_alloc = alloc_nr(rename_dst_alloc);
  43                rename_dst = xrealloc(rename_dst,
  44                                      rename_dst_alloc * sizeof(*rename_dst));
  45        }
  46        rename_dst_nr++;
  47        if (first < rename_dst_nr)
  48                memmove(rename_dst + first + 1, rename_dst + first,
  49                        (rename_dst_nr - first - 1) * sizeof(*rename_dst));
  50        rename_dst[first].two = alloc_filespec(two->path);
  51        fill_filespec(rename_dst[first].two, two->sha1, two->mode);
  52        rename_dst[first].pair = NULL;
  53        return &(rename_dst[first]);
  54}
  55
  56/* Table of rename/copy src files */
  57static struct diff_rename_src {
  58        struct diff_filespec *one;
  59        unsigned short score; /* to remember the break score */
  60} *rename_src;
  61static int rename_src_nr, rename_src_alloc;
  62
  63static struct diff_rename_src *register_rename_src(struct diff_filespec *one,
  64                                                   unsigned short score)
  65{
  66        int first, last;
  67
  68        first = 0;
  69        last = rename_src_nr;
  70        while (last > first) {
  71                int next = (last + first) >> 1;
  72                struct diff_rename_src *src = &(rename_src[next]);
  73                int cmp = strcmp(one->path, src->one->path);
  74                if (!cmp)
  75                        return src;
  76                if (cmp < 0) {
  77                        last = next;
  78                        continue;
  79                }
  80                first = next+1;
  81        }
  82
  83        /* insert to make it at "first" */
  84        if (rename_src_alloc <= rename_src_nr) {
  85                rename_src_alloc = alloc_nr(rename_src_alloc);
  86                rename_src = xrealloc(rename_src,
  87                                      rename_src_alloc * sizeof(*rename_src));
  88        }
  89        rename_src_nr++;
  90        if (first < rename_src_nr)
  91                memmove(rename_src + first + 1, rename_src + first,
  92                        (rename_src_nr - first - 1) * sizeof(*rename_src));
  93        rename_src[first].one = one;
  94        rename_src[first].score = score;
  95        return &(rename_src[first]);
  96}
  97
  98static int basename_same(struct diff_filespec *src, struct diff_filespec *dst)
  99{
 100        int src_len = strlen(src->path), dst_len = strlen(dst->path);
 101        while (src_len && dst_len) {
 102                char c1 = src->path[--src_len];
 103                char c2 = dst->path[--dst_len];
 104                if (c1 != c2)
 105                        return 0;
 106                if (c1 == '/')
 107                        return 1;
 108        }
 109        return (!src_len || src->path[src_len - 1] == '/') &&
 110                (!dst_len || dst->path[dst_len - 1] == '/');
 111}
 112
 113struct diff_score {
 114        int src; /* index in rename_src */
 115        int dst; /* index in rename_dst */
 116        unsigned short score;
 117        short name_score;
 118};
 119
 120static int estimate_similarity(struct diff_filespec *src,
 121                               struct diff_filespec *dst,
 122                               int minimum_score)
 123{
 124        /* src points at a file that existed in the original tree (or
 125         * optionally a file in the destination tree) and dst points
 126         * at a newly created file.  They may be quite similar, in which
 127         * case we want to say src is renamed to dst or src is copied into
 128         * dst, and then some edit has been applied to dst.
 129         *
 130         * Compare them and return how similar they are, representing
 131         * the score as an integer between 0 and MAX_SCORE.
 132         *
 133         * When there is an exact match, it is considered a better
 134         * match than anything else; the destination does not even
 135         * call into this function in that case.
 136         */
 137        unsigned long max_size, delta_size, base_size, src_copied, literal_added;
 138        unsigned long delta_limit;
 139        int score;
 140
 141        /* We deal only with regular files.  Symlink renames are handled
 142         * only when they are exact matches --- in other words, no edits
 143         * after renaming.
 144         */
 145        if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
 146                return 0;
 147
 148        /*
 149         * Need to check that source and destination sizes are
 150         * filled in before comparing them.
 151         *
 152         * If we already have "cnt_data" filled in, we know it's
 153         * all good (avoid checking the size for zero, as that
 154         * is a possible size - we really should have a flag to
 155         * say whether the size is valid or not!)
 156         */
 157        if (!src->cnt_data && diff_populate_filespec(src, 1))
 158                return 0;
 159        if (!dst->cnt_data && diff_populate_filespec(dst, 1))
 160                return 0;
 161
 162        max_size = ((src->size > dst->size) ? src->size : dst->size);
 163        base_size = ((src->size < dst->size) ? src->size : dst->size);
 164        delta_size = max_size - base_size;
 165
 166        /* We would not consider edits that change the file size so
 167         * drastically.  delta_size must be smaller than
 168         * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
 169         *
 170         * Note that base_size == 0 case is handled here already
 171         * and the final score computation below would not have a
 172         * divide-by-zero issue.
 173         */
 174        if (max_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
 175                return 0;
 176
 177        if (!src->cnt_data && diff_populate_filespec(src, 0))
 178                return 0;
 179        if (!dst->cnt_data && diff_populate_filespec(dst, 0))
 180                return 0;
 181
 182        delta_limit = (unsigned long)
 183                (base_size * (MAX_SCORE-minimum_score) / MAX_SCORE);
 184        if (diffcore_count_changes(src, dst,
 185                                   &src->cnt_data, &dst->cnt_data,
 186                                   delta_limit,
 187                                   &src_copied, &literal_added))
 188                return 0;
 189
 190        /* How similar are they?
 191         * what percentage of material in dst are from source?
 192         */
 193        if (!dst->size)
 194                score = 0; /* should not happen */
 195        else
 196                score = (int)(src_copied * MAX_SCORE / max_size);
 197        return score;
 198}
 199
 200static void record_rename_pair(int dst_index, int src_index, int score)
 201{
 202        struct diff_filespec *src, *dst;
 203        struct diff_filepair *dp;
 204
 205        if (rename_dst[dst_index].pair)
 206                die("internal error: dst already matched.");
 207
 208        src = rename_src[src_index].one;
 209        src->rename_used++;
 210        src->count++;
 211
 212        dst = rename_dst[dst_index].two;
 213        dst->count++;
 214
 215        dp = diff_queue(NULL, src, dst);
 216        dp->renamed_pair = 1;
 217        if (!strcmp(src->path, dst->path))
 218                dp->score = rename_src[src_index].score;
 219        else
 220                dp->score = score;
 221        rename_dst[dst_index].pair = dp;
 222}
 223
 224/*
 225 * We sort the rename similarity matrix with the score, in descending
 226 * order (the most similar first).
 227 */
 228static int score_compare(const void *a_, const void *b_)
 229{
 230        const struct diff_score *a = a_, *b = b_;
 231
 232        /* sink the unused ones to the bottom */
 233        if (a->dst < 0)
 234                return (0 <= b->dst);
 235        else if (b->dst < 0)
 236                return -1;
 237
 238        if (a->score == b->score)
 239                return b->name_score - a->name_score;
 240
 241        return b->score - a->score;
 242}
 243
 244struct file_similarity {
 245        int src_dst, index;
 246        struct diff_filespec *filespec;
 247        struct file_similarity *next;
 248};
 249
 250static int find_identical_files(struct file_similarity *src,
 251                                struct file_similarity *dst,
 252                                struct diff_options *options)
 253{
 254        int renames = 0;
 255
 256        /*
 257         * Walk over all the destinations ...
 258         */
 259        do {
 260                struct diff_filespec *target = dst->filespec;
 261                struct file_similarity *p, *best;
 262                int i = 100, best_score = -1;
 263
 264                /*
 265                 * .. to find the best source match
 266                 */
 267                best = NULL;
 268                for (p = src; p; p = p->next) {
 269                        int score;
 270                        struct diff_filespec *source = p->filespec;
 271
 272                        /* False hash collision? */
 273                        if (hashcmp(source->sha1, target->sha1))
 274                                continue;
 275                        /* Non-regular files? If so, the modes must match! */
 276                        if (!S_ISREG(source->mode) || !S_ISREG(target->mode)) {
 277                                if (source->mode != target->mode)
 278                                        continue;
 279                        }
 280                        /* Give higher scores to sources that haven't been used already */
 281                        score = !source->rename_used;
 282                        if (source->rename_used && options->detect_rename != DIFF_DETECT_COPY)
 283                                continue;
 284                        score += basename_same(source, target);
 285                        if (score > best_score) {
 286                                best = p;
 287                                best_score = score;
 288                                if (score == 2)
 289                                        break;
 290                        }
 291
 292                        /* Too many identical alternatives? Pick one */
 293                        if (!--i)
 294                                break;
 295                }
 296                if (best) {
 297                        record_rename_pair(dst->index, best->index, MAX_SCORE);
 298                        renames++;
 299                }
 300        } while ((dst = dst->next) != NULL);
 301        return renames;
 302}
 303
 304static void free_similarity_list(struct file_similarity *p)
 305{
 306        while (p) {
 307                struct file_similarity *entry = p;
 308                p = p->next;
 309                free(entry);
 310        }
 311}
 312
 313static int find_same_files(void *ptr, void *data)
 314{
 315        int ret;
 316        struct file_similarity *p = ptr;
 317        struct file_similarity *src = NULL, *dst = NULL;
 318        struct diff_options *options = data;
 319
 320        /* Split the hash list up into sources and destinations */
 321        do {
 322                struct file_similarity *entry = p;
 323                p = p->next;
 324                if (entry->src_dst < 0) {
 325                        entry->next = src;
 326                        src = entry;
 327                } else {
 328                        entry->next = dst;
 329                        dst = entry;
 330                }
 331        } while (p);
 332
 333        /*
 334         * If we have both sources *and* destinations, see if
 335         * we can match them up
 336         */
 337        ret = (src && dst) ? find_identical_files(src, dst, options) : 0;
 338
 339        /* Free the hashes and return the number of renames found */
 340        free_similarity_list(src);
 341        free_similarity_list(dst);
 342        return ret;
 343}
 344
 345static unsigned int hash_filespec(struct diff_filespec *filespec)
 346{
 347        unsigned int hash;
 348        if (!filespec->sha1_valid) {
 349                if (diff_populate_filespec(filespec, 0))
 350                        return 0;
 351                hash_sha1_file(filespec->data, filespec->size, "blob", filespec->sha1);
 352        }
 353        memcpy(&hash, filespec->sha1, sizeof(hash));
 354        return hash;
 355}
 356
 357static void insert_file_table(struct hash_table *table, int src_dst, int index, struct diff_filespec *filespec)
 358{
 359        void **pos;
 360        unsigned int hash;
 361        struct file_similarity *entry = xmalloc(sizeof(*entry));
 362
 363        entry->src_dst = src_dst;
 364        entry->index = index;
 365        entry->filespec = filespec;
 366        entry->next = NULL;
 367
 368        hash = hash_filespec(filespec);
 369        pos = insert_hash(hash, entry, table);
 370
 371        /* We already had an entry there? */
 372        if (pos) {
 373                entry->next = *pos;
 374                *pos = entry;
 375        }
 376}
 377
 378/*
 379 * Find exact renames first.
 380 *
 381 * The first round matches up the up-to-date entries,
 382 * and then during the second round we try to match
 383 * cache-dirty entries as well.
 384 */
 385static int find_exact_renames(struct diff_options *options)
 386{
 387        int i;
 388        struct hash_table file_table;
 389
 390        init_hash(&file_table);
 391        for (i = 0; i < rename_src_nr; i++)
 392                insert_file_table(&file_table, -1, i, rename_src[i].one);
 393
 394        for (i = 0; i < rename_dst_nr; i++)
 395                insert_file_table(&file_table, 1, i, rename_dst[i].two);
 396
 397        /* Find the renames */
 398        i = for_each_hash(&file_table, find_same_files, options);
 399
 400        /* .. and free the hash data structure */
 401        free_hash(&file_table);
 402
 403        return i;
 404}
 405
 406#define NUM_CANDIDATE_PER_DST 4
 407static void record_if_better(struct diff_score m[], struct diff_score *o)
 408{
 409        int i, worst;
 410
 411        /* find the worst one */
 412        worst = 0;
 413        for (i = 1; i < NUM_CANDIDATE_PER_DST; i++)
 414                if (score_compare(&m[i], &m[worst]) > 0)
 415                        worst = i;
 416
 417        /* is it better than the worst one? */
 418        if (score_compare(&m[worst], o) > 0)
 419                m[worst] = *o;
 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].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        int rename_limit = options->rename_limit;
 448        struct diff_queue_struct *q = &diff_queued_diff;
 449        struct diff_queue_struct outq;
 450        struct diff_score *mx;
 451        int i, j, rename_count;
 452        int num_create, num_src, dst_cnt;
 453        struct progress *progress = NULL;
 454
 455        if (!minimum_score)
 456                minimum_score = DEFAULT_RENAME_SCORE;
 457
 458        for (i = 0; i < q->nr; i++) {
 459                struct diff_filepair *p = q->queue[i];
 460                if (!DIFF_FILE_VALID(p->one)) {
 461                        if (!DIFF_FILE_VALID(p->two))
 462                                continue; /* unmerged */
 463                        else if (options->single_follow &&
 464                                 strcmp(options->single_follow, p->two->path))
 465                                continue; /* not interested */
 466                        else
 467                                locate_rename_dst(p->two, 1);
 468                }
 469                else if (!DIFF_PAIR_UNMERGED(p) && !DIFF_FILE_VALID(p->two)) {
 470                        /*
 471                         * If the source is a broken "delete", and
 472                         * they did not really want to get broken,
 473                         * that means the source actually stays.
 474                         * So we increment the "rename_used" score
 475                         * by one, to indicate ourselves as a user
 476                         */
 477                        if (p->broken_pair && !p->score)
 478                                p->one->rename_used++;
 479                        register_rename_src(p->one, p->score);
 480                }
 481                else if (detect_rename == DIFF_DETECT_COPY) {
 482                        /*
 483                         * Increment the "rename_used" score by
 484                         * one, to indicate ourselves as a user.
 485                         */
 486                        p->one->rename_used++;
 487                        register_rename_src(p->one, p->score);
 488                }
 489        }
 490        if (rename_dst_nr == 0 || rename_src_nr == 0)
 491                goto cleanup; /* nothing to do */
 492
 493        /*
 494         * We really want to cull the candidates list early
 495         * with cheap tests in order to avoid doing deltas.
 496         */
 497        rename_count = find_exact_renames(options);
 498
 499        /* Did we only want exact renames? */
 500        if (minimum_score == MAX_SCORE)
 501                goto cleanup;
 502
 503        /*
 504         * Calculate how many renames are left (but all the source
 505         * files still remain as options for rename/copies!)
 506         */
 507        num_create = (rename_dst_nr - rename_count);
 508        num_src = rename_src_nr;
 509
 510        /* All done? */
 511        if (!num_create)
 512                goto cleanup;
 513
 514        /*
 515         * This basically does a test for the rename matrix not
 516         * growing larger than a "rename_limit" square matrix, ie:
 517         *
 518         *    num_create * num_src > rename_limit * rename_limit
 519         *
 520         * but handles the potential overflow case specially (and we
 521         * assume at least 32-bit integers)
 522         */
 523        options->needed_rename_limit = 0;
 524        if (rename_limit <= 0 || rename_limit > 32767)
 525                rename_limit = 32767;
 526        if ((num_create > rename_limit && num_src > rename_limit) ||
 527            (num_create * num_src > rename_limit * rename_limit)) {
 528                options->needed_rename_limit =
 529                        num_src > num_create ? num_src : num_create;
 530                goto cleanup;
 531        }
 532
 533        if (options->show_rename_progress) {
 534                progress = start_progress_delay(
 535                                "Performing inexact rename detection",
 536                                rename_dst_nr * rename_src_nr, 50, 1);
 537        }
 538
 539        mx = xcalloc(num_create * NUM_CANDIDATE_PER_DST, 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].one;
 553                        struct diff_score this_src;
 554                        this_src.score = estimate_similarity(one, two,
 555                                                             minimum_score);
 556                        this_src.name_score = basename_same(one, two);
 557                        this_src.dst = i;
 558                        this_src.src = j;
 559                        record_if_better(m, &this_src);
 560                        /*
 561                         * Once we run estimate_similarity,
 562                         * We do not need the text anymore.
 563                         */
 564                        diff_free_filespec_blob(one);
 565                        diff_free_filespec_blob(two);
 566                }
 567                dst_cnt++;
 568                display_progress(progress, (i+1)*rename_src_nr);
 569        }
 570        stop_progress(&progress);
 571
 572        /* cost matrix sorted by most to least similar pair */
 573        qsort(mx, dst_cnt * NUM_CANDIDATE_PER_DST, sizeof(*mx), score_compare);
 574
 575        rename_count += find_renames(mx, dst_cnt, minimum_score, 0);
 576        if (detect_rename == DIFF_DETECT_COPY)
 577                rename_count += find_renames(mx, dst_cnt, minimum_score, 1);
 578        free(mx);
 579
 580 cleanup:
 581        /* At this point, we have found some renames and copies and they
 582         * are recorded in rename_dst.  The original list is still in *q.
 583         */
 584        DIFF_QUEUE_CLEAR(&outq);
 585        for (i = 0; i < q->nr; i++) {
 586                struct diff_filepair *p = q->queue[i];
 587                struct diff_filepair *pair_to_free = NULL;
 588
 589                if (DIFF_PAIR_UNMERGED(p)) {
 590                        diff_q(&outq, p);
 591                }
 592                else if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
 593                        /*
 594                         * Creation
 595                         *
 596                         * We would output this create record if it has
 597                         * not been turned into a rename/copy already.
 598                         */
 599                        struct diff_rename_dst *dst =
 600                                locate_rename_dst(p->two, 0);
 601                        if (dst && dst->pair) {
 602                                diff_q(&outq, dst->pair);
 603                                pair_to_free = p;
 604                        }
 605                        else
 606                                /* no matching rename/copy source, so
 607                                 * record this as a creation.
 608                                 */
 609                                diff_q(&outq, p);
 610                }
 611                else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
 612                        /*
 613                         * Deletion
 614                         *
 615                         * We would output this delete record if:
 616                         *
 617                         * (1) this is a broken delete and the counterpart
 618                         *     broken create remains in the output; or
 619                         * (2) this is not a broken delete, and rename_dst
 620                         *     does not have a rename/copy to move p->one->path
 621                         *     out of existence.
 622                         *
 623                         * Otherwise, the counterpart broken create
 624                         * has been turned into a rename-edit; or
 625                         * delete did not have a matching create to
 626                         * begin with.
 627                         */
 628                        if (DIFF_PAIR_BROKEN(p)) {
 629                                /* broken delete */
 630                                struct diff_rename_dst *dst =
 631                                        locate_rename_dst(p->one, 0);
 632                                if (dst && dst->pair)
 633                                        /* counterpart is now rename/copy */
 634                                        pair_to_free = p;
 635                        }
 636                        else {
 637                                if (p->one->rename_used)
 638                                        /* this path remains */
 639                                        pair_to_free = p;
 640                        }
 641
 642                        if (pair_to_free)
 643                                ;
 644                        else
 645                                diff_q(&outq, p);
 646                }
 647                else if (!diff_unmodified_pair(p))
 648                        /* all the usual ones need to be kept */
 649                        diff_q(&outq, p);
 650                else
 651                        /* no need to keep unmodified pairs */
 652                        pair_to_free = p;
 653
 654                if (pair_to_free)
 655                        diff_free_filepair(pair_to_free);
 656        }
 657        diff_debug_queue("done copying original", &outq);
 658
 659        free(q->queue);
 660        *q = outq;
 661        diff_debug_queue("done collapsing", q);
 662
 663        for (i = 0; i < rename_dst_nr; i++)
 664                free_filespec(rename_dst[i].two);
 665
 666        free(rename_dst);
 667        rename_dst = NULL;
 668        rename_dst_nr = rename_dst_alloc = 0;
 669        free(rename_src);
 670        rename_src = NULL;
 671        rename_src_nr = rename_src_alloc = 0;
 672        return;
 673}