Andrew's git - gitweb.git/blob

   1/*
   2 *  LibXDiff by Davide Libenzi ( File Differential Library )
   3 *  Copyright (C) 2003  Davide Libenzi
   4 *
   5 *  This library is free software; you can redistribute it and/or
   6 *  modify it under the terms of the GNU Lesser General Public
   7 *  License as published by the Free Software Foundation; either
   8 *  version 2.1 of the License, or (at your option) any later version.
   9 *
  10 *  This library is distributed in the hope that it will be useful,
  11 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13 *  Lesser General Public License for more details.
  14 *
  15 *  You should have received a copy of the GNU Lesser General Public
  16 *  License along with this library; if not, write to the Free Software
  17 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18 *
  19 *  Davide Libenzi <davidel@xmailserver.org>
  20 *
  21 */
  22
  23#include "xinclude.h"
  24
  25
  26#define XDL_KPDIS_RUN 4
  27#define XDL_MAX_EQLIMIT 1024
  28#define XDL_SIMSCAN_WINDOW 100
  29
  30
  31typedef struct s_xdlclass {
  32        struct s_xdlclass *next;
  33        unsigned long ha;
  34        char const *line;
  35        long size;
  36        long idx;
  37} xdlclass_t;
  38
  39typedef struct s_xdlclassifier {
  40        unsigned int hbits;
  41        long hsize;
  42        xdlclass_t **rchash;
  43        chastore_t ncha;
  44        long count;
  45        long flags;
  46} xdlclassifier_t;
  47
  48
  49
  50
  51static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags);
  52static void xdl_free_classifier(xdlclassifier_t *cf);
  53static int xdl_classify_record(xdlclassifier_t *cf, xrecord_t **rhash, unsigned int hbits,
  54                               xrecord_t *rec);
  55static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
  56                           xdlclassifier_t *cf, xdfile_t *xdf);
  57static void xdl_free_ctx(xdfile_t *xdf);
  58static int xdl_clean_mmatch(char const *dis, long i, long s, long e);
  59static int xdl_cleanup_records(xdfile_t *xdf1, xdfile_t *xdf2);
  60static int xdl_trim_ends(xdfile_t *xdf1, xdfile_t *xdf2);
  61static int xdl_optimize_ctxs(xdfile_t *xdf1, xdfile_t *xdf2);
  62
  63
  64
  65
  66static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags) {
  67        cf->flags = flags;
  68
  69        cf->hbits = xdl_hashbits((unsigned int) size);
  70        cf->hsize = 1 << cf->hbits;
  71
  72        if (xdl_cha_init(&cf->ncha, sizeof(xdlclass_t), size / 4 + 1) < 0) {
  73
  74                return -1;
  75        }
  76        if (!(cf->rchash = (xdlclass_t **) xdl_malloc(cf->hsize * sizeof(xdlclass_t *)))) {
  77
  78                xdl_cha_free(&cf->ncha);
  79                return -1;
  80        }
  81        memset(cf->rchash, 0, cf->hsize * sizeof(xdlclass_t *));
  82
  83        cf->count = 0;
  84
  85        return 0;
  86}
  87
  88
  89static void xdl_free_classifier(xdlclassifier_t *cf) {
  90
  91        xdl_free(cf->rchash);
  92        xdl_cha_free(&cf->ncha);
  93}
  94
  95
  96static int xdl_classify_record(xdlclassifier_t *cf, xrecord_t **rhash, unsigned int hbits,
  97                               xrecord_t *rec) {
  98        long hi;
  99        char const *line;
 100        xdlclass_t *rcrec;
 101
 102        line = rec->ptr;
 103        hi = (long) XDL_HASHLONG(rec->ha, cf->hbits);
 104        for (rcrec = cf->rchash[hi]; rcrec; rcrec = rcrec->next)
 105                if (rcrec->ha == rec->ha &&
 106                                xdl_recmatch(rcrec->line, rcrec->size,
 107                                        rec->ptr, rec->size, cf->flags))
 108                        break;
 109
 110        if (!rcrec) {
 111                if (!(rcrec = xdl_cha_alloc(&cf->ncha))) {
 112
 113                        return -1;
 114                }
 115                rcrec->idx = cf->count++;
 116                rcrec->line = line;
 117                rcrec->size = rec->size;
 118                rcrec->ha = rec->ha;
 119                rcrec->next = cf->rchash[hi];
 120                cf->rchash[hi] = rcrec;
 121        }
 122
 123        rec->ha = (unsigned long) rcrec->idx;
 124
 125        hi = (long) XDL_HASHLONG(rec->ha, hbits);
 126        rec->next = rhash[hi];
 127        rhash[hi] = rec;
 128
 129        return 0;
 130}
 131
 132
 133static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
 134                           xdlclassifier_t *cf, xdfile_t *xdf) {
 135        unsigned int hbits;
 136        long nrec, hsize, bsize;
 137        unsigned long hav;
 138        char const *blk, *cur, *top, *prev;
 139        xrecord_t *crec;
 140        xrecord_t **recs, **rrecs;
 141        xrecord_t **rhash;
 142        unsigned long *ha;
 143        char *rchg;
 144        long *rindex;
 145
 146        if (xdl_cha_init(&xdf->rcha, sizeof(xrecord_t), narec / 4 + 1) < 0) {
 147
 148                return -1;
 149        }
 150        if (!(recs = (xrecord_t **) xdl_malloc(narec * sizeof(xrecord_t *)))) {
 151
 152                xdl_cha_free(&xdf->rcha);
 153                return -1;
 154        }
 155
 156        hbits = xdl_hashbits((unsigned int) narec);
 157        hsize = 1 << hbits;
 158        if (!(rhash = (xrecord_t **) xdl_malloc(hsize * sizeof(xrecord_t *)))) {
 159
 160                xdl_free(recs);
 161                xdl_cha_free(&xdf->rcha);
 162                return -1;
 163        }
 164        memset(rhash, 0, hsize * sizeof(xrecord_t *));
 165
 166        nrec = 0;
 167        if ((cur = blk = xdl_mmfile_first(mf, &bsize)) != NULL) {
 168                for (top = blk + bsize;;) {
 169                        if (cur >= top) {
 170                                if (!(cur = blk = xdl_mmfile_next(mf, &bsize)))
 171                                        break;
 172                                top = blk + bsize;
 173                        }
 174                        prev = cur;
 175                        hav = xdl_hash_record(&cur, top, xpp->flags);
 176                        if (nrec >= narec) {
 177                                narec *= 2;
 178                                if (!(rrecs = (xrecord_t **) xdl_realloc(recs, narec * sizeof(xrecord_t *)))) {
 179
 180                                        xdl_free(rhash);
 181                                        xdl_free(recs);
 182                                        xdl_cha_free(&xdf->rcha);
 183                                        return -1;
 184                                }
 185                                recs = rrecs;
 186                        }
 187                        if (!(crec = xdl_cha_alloc(&xdf->rcha))) {
 188
 189                                xdl_free(rhash);
 190                                xdl_free(recs);
 191                                xdl_cha_free(&xdf->rcha);
 192                                return -1;
 193                        }
 194                        crec->ptr = prev;
 195                        crec->size = (long) (cur - prev);
 196                        crec->ha = hav;
 197                        recs[nrec++] = crec;
 198
 199                        if (xdl_classify_record(cf, rhash, hbits, crec) < 0) {
 200
 201                                xdl_free(rhash);
 202                                xdl_free(recs);
 203                                xdl_cha_free(&xdf->rcha);
 204                                return -1;
 205                        }
 206                }
 207        }
 208
 209        if (!(rchg = (char *) xdl_malloc((nrec + 2) * sizeof(char)))) {
 210
 211                xdl_free(rhash);
 212                xdl_free(recs);
 213                xdl_cha_free(&xdf->rcha);
 214                return -1;
 215        }
 216        memset(rchg, 0, (nrec + 2) * sizeof(char));
 217
 218        if (!(rindex = (long *) xdl_malloc((nrec + 1) * sizeof(long)))) {
 219
 220                xdl_free(rchg);
 221                xdl_free(rhash);
 222                xdl_free(recs);
 223                xdl_cha_free(&xdf->rcha);
 224                return -1;
 225        }
 226        if (!(ha = (unsigned long *) xdl_malloc((nrec + 1) * sizeof(unsigned long)))) {
 227
 228                xdl_free(rindex);
 229                xdl_free(rchg);
 230                xdl_free(rhash);
 231                xdl_free(recs);
 232                xdl_cha_free(&xdf->rcha);
 233                return -1;
 234        }
 235
 236        xdf->nrec = nrec;
 237        xdf->recs = recs;
 238        xdf->hbits = hbits;
 239        xdf->rhash = rhash;
 240        xdf->rchg = rchg + 1;
 241        xdf->rindex = rindex;
 242        xdf->nreff = 0;
 243        xdf->ha = ha;
 244        xdf->dstart = 0;
 245        xdf->dend = nrec - 1;
 246
 247        return 0;
 248}
 249
 250
 251static void xdl_free_ctx(xdfile_t *xdf) {
 252
 253        xdl_free(xdf->rhash);
 254        xdl_free(xdf->rindex);
 255        xdl_free(xdf->rchg - 1);
 256        xdl_free(xdf->ha);
 257        xdl_free(xdf->recs);
 258        xdl_cha_free(&xdf->rcha);
 259}
 260
 261
 262int xdl_prepare_env(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
 263                    xdfenv_t *xe) {
 264        long enl1, enl2;
 265        xdlclassifier_t cf;
 266
 267        enl1 = xdl_guess_lines(mf1) + 1;
 268        enl2 = xdl_guess_lines(mf2) + 1;
 269
 270        if (xdl_init_classifier(&cf, enl1 + enl2 + 1, xpp->flags) < 0) {
 271
 272                return -1;
 273        }
 274
 275        if (xdl_prepare_ctx(mf1, enl1, xpp, &cf, &xe->xdf1) < 0) {
 276
 277                xdl_free_classifier(&cf);
 278                return -1;
 279        }
 280        if (xdl_prepare_ctx(mf2, enl2, xpp, &cf, &xe->xdf2) < 0) {
 281
 282                xdl_free_ctx(&xe->xdf1);
 283                xdl_free_classifier(&cf);
 284                return -1;
 285        }
 286
 287        xdl_free_classifier(&cf);
 288
 289        if (!(xpp->flags & XDF_PATIENCE_DIFF) &&
 290                        xdl_optimize_ctxs(&xe->xdf1, &xe->xdf2) < 0) {
 291
 292                xdl_free_ctx(&xe->xdf2);
 293                xdl_free_ctx(&xe->xdf1);
 294                return -1;
 295        }
 296
 297        return 0;
 298}
 299
 300
 301void xdl_free_env(xdfenv_t *xe) {
 302
 303        xdl_free_ctx(&xe->xdf2);
 304        xdl_free_ctx(&xe->xdf1);
 305}
 306
 307
 308static int xdl_clean_mmatch(char const *dis, long i, long s, long e) {
 309        long r, rdis0, rpdis0, rdis1, rpdis1;
 310
 311        /*
 312         * Limits the window the is examined during the similar-lines
 313         * scan. The loops below stops when dis[i - r] == 1 (line that
 314         * has no match), but there are corner cases where the loop
 315         * proceed all the way to the extremities by causing huge
 316         * performance penalties in case of big files.
 317         */
 318        if (i - s > XDL_SIMSCAN_WINDOW)
 319                s = i - XDL_SIMSCAN_WINDOW;
 320        if (e - i > XDL_SIMSCAN_WINDOW)
 321                e = i + XDL_SIMSCAN_WINDOW;
 322
 323        /*
 324         * Scans the lines before 'i' to find a run of lines that either
 325         * have no match (dis[j] == 0) or have multiple matches (dis[j] > 1).
 326         * Note that we always call this function with dis[i] > 1, so the
 327         * current line (i) is already a multimatch line.
 328         */
 329        for (r = 1, rdis0 = 0, rpdis0 = 1; (i - r) >= s; r++) {
 330                if (!dis[i - r])
 331                        rdis0++;
 332                else if (dis[i - r] == 2)
 333                        rpdis0++;
 334                else
 335                        break;
 336        }
 337        /*
 338         * If the run before the line 'i' found only multimatch lines, we
 339         * return 0 and hence we don't make the current line (i) discarded.
 340         * We want to discard multimatch lines only when they appear in the
 341         * middle of runs with nomatch lines (dis[j] == 0).
 342         */
 343        if (rdis0 == 0)
 344                return 0;
 345        for (r = 1, rdis1 = 0, rpdis1 = 1; (i + r) <= e; r++) {
 346                if (!dis[i + r])
 347                        rdis1++;
 348                else if (dis[i + r] == 2)
 349                        rpdis1++;
 350                else
 351                        break;
 352        }
 353        /*
 354         * If the run after the line 'i' found only multimatch lines, we
 355         * return 0 and hence we don't make the current line (i) discarded.
 356         */
 357        if (rdis1 == 0)
 358                return 0;
 359        rdis1 += rdis0;
 360        rpdis1 += rpdis0;
 361
 362        return rpdis1 * XDL_KPDIS_RUN < (rpdis1 + rdis1);
 363}
 364
 365
 366/*
 367 * Try to reduce the problem complexity, discard records that have no
 368 * matches on the other file. Also, lines that have multiple matches
 369 * might be potentially discarded if they happear in a run of discardable.
 370 */
 371static int xdl_cleanup_records(xdfile_t *xdf1, xdfile_t *xdf2) {
 372        long i, nm, rhi, nreff, mlim;
 373        unsigned long hav;
 374        xrecord_t **recs;
 375        xrecord_t *rec;
 376        char *dis, *dis1, *dis2;
 377
 378        if (!(dis = (char *) xdl_malloc(xdf1->nrec + xdf2->nrec + 2))) {
 379
 380                return -1;
 381        }
 382        memset(dis, 0, xdf1->nrec + xdf2->nrec + 2);
 383        dis1 = dis;
 384        dis2 = dis1 + xdf1->nrec + 1;
 385
 386        if ((mlim = xdl_bogosqrt(xdf1->nrec)) > XDL_MAX_EQLIMIT)
 387                mlim = XDL_MAX_EQLIMIT;
 388        for (i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart]; i <= xdf1->dend; i++, recs++) {
 389                hav = (*recs)->ha;
 390                rhi = (long) XDL_HASHLONG(hav, xdf2->hbits);
 391                for (nm = 0, rec = xdf2->rhash[rhi]; rec; rec = rec->next)
 392                        if (rec->ha == hav && ++nm == mlim)
 393                                break;
 394                dis1[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
 395        }
 396
 397        if ((mlim = xdl_bogosqrt(xdf2->nrec)) > XDL_MAX_EQLIMIT)
 398                mlim = XDL_MAX_EQLIMIT;
 399        for (i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart]; i <= xdf2->dend; i++, recs++) {
 400                hav = (*recs)->ha;
 401                rhi = (long) XDL_HASHLONG(hav, xdf1->hbits);
 402                for (nm = 0, rec = xdf1->rhash[rhi]; rec; rec = rec->next)
 403                        if (rec->ha == hav && ++nm == mlim)
 404                                break;
 405                dis2[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
 406        }
 407
 408        for (nreff = 0, i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart];
 409             i <= xdf1->dend; i++, recs++) {
 410                if (dis1[i] == 1 ||
 411                    (dis1[i] == 2 && !xdl_clean_mmatch(dis1, i, xdf1->dstart, xdf1->dend))) {
 412                        xdf1->rindex[nreff] = i;
 413                        xdf1->ha[nreff] = (*recs)->ha;
 414                        nreff++;
 415                } else
 416                        xdf1->rchg[i] = 1;
 417        }
 418        xdf1->nreff = nreff;
 419
 420        for (nreff = 0, i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart];
 421             i <= xdf2->dend; i++, recs++) {
 422                if (dis2[i] == 1 ||
 423                    (dis2[i] == 2 && !xdl_clean_mmatch(dis2, i, xdf2->dstart, xdf2->dend))) {
 424                        xdf2->rindex[nreff] = i;
 425                        xdf2->ha[nreff] = (*recs)->ha;
 426                        nreff++;
 427                } else
 428                        xdf2->rchg[i] = 1;
 429        }
 430        xdf2->nreff = nreff;
 431
 432        xdl_free(dis);
 433
 434        return 0;
 435}
 436
 437
 438/*
 439 * Early trim initial and terminal matching records.
 440 */
 441static int xdl_trim_ends(xdfile_t *xdf1, xdfile_t *xdf2) {
 442        long i, lim;
 443        xrecord_t **recs1, **recs2;
 444
 445        recs1 = xdf1->recs;
 446        recs2 = xdf2->recs;
 447        for (i = 0, lim = XDL_MIN(xdf1->nrec, xdf2->nrec); i < lim;
 448             i++, recs1++, recs2++)
 449                if ((*recs1)->ha != (*recs2)->ha)
 450                        break;
 451
 452        xdf1->dstart = xdf2->dstart = i;
 453
 454        recs1 = xdf1->recs + xdf1->nrec - 1;
 455        recs2 = xdf2->recs + xdf2->nrec - 1;
 456        for (lim -= i, i = 0; i < lim; i++, recs1--, recs2--)
 457                if ((*recs1)->ha != (*recs2)->ha)
 458                        break;
 459
 460        xdf1->dend = xdf1->nrec - i - 1;
 461        xdf2->dend = xdf2->nrec - i - 1;
 462
 463        return 0;
 464}
 465
 466
 467static int xdl_optimize_ctxs(xdfile_t *xdf1, xdfile_t *xdf2) {
 468
 469        if (xdl_trim_ends(xdf1, xdf2) < 0 ||
 470            xdl_cleanup_records(xdf1, xdf2) < 0) {
 471
 472                return -1;
 473        }
 474
 475        return 0;
 476}