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, see
  17 *  <http://www.gnu.org/licenses/>.
  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#define XDL_GUESS_NLINES1 256
  30#define XDL_GUESS_NLINES2 20
  31
  32
  33typedef struct s_xdlclass {
  34        struct s_xdlclass *next;
  35        unsigned long ha;
  36        char const *line;
  37        long size;
  38        long idx;
  39        long len1, len2;
  40} xdlclass_t;
  41
  42typedef struct s_xdlclassifier {
  43        unsigned int hbits;
  44        long hsize;
  45        xdlclass_t **rchash;
  46        chastore_t ncha;
  47        xdlclass_t **rcrecs;
  48        long alloc;
  49        long count;
  50        long flags;
  51} xdlclassifier_t;
  52
  53
  54
  55
  56static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags);
  57static void xdl_free_classifier(xdlclassifier_t *cf);
  58static int xdl_classify_record(unsigned int pass, xdlclassifier_t *cf, xrecord_t **rhash,
  59                               unsigned int hbits, xrecord_t *rec);
  60static int xdl_prepare_ctx(unsigned int pass, mmfile_t *mf, long narec, xpparam_t const *xpp,
  61                           xdlclassifier_t *cf, xdfile_t *xdf);
  62static void xdl_free_ctx(xdfile_t *xdf);
  63static int xdl_clean_mmatch(char const *dis, long i, long s, long e);
  64static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2);
  65static int xdl_trim_ends(xdfile_t *xdf1, xdfile_t *xdf2);
  66static int xdl_optimize_ctxs(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2);
  67
  68
  69
  70
  71static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags) {
  72        cf->flags = flags;
  73
  74        cf->hbits = xdl_hashbits((unsigned int) size);
  75        cf->hsize = 1 << cf->hbits;
  76
  77        if (xdl_cha_init(&cf->ncha, sizeof(xdlclass_t), size / 4 + 1) < 0) {
  78
  79                return -1;
  80        }
  81        if (!(cf->rchash = (xdlclass_t **) xdl_malloc(cf->hsize * sizeof(xdlclass_t *)))) {
  82
  83                xdl_cha_free(&cf->ncha);
  84                return -1;
  85        }
  86        memset(cf->rchash, 0, cf->hsize * sizeof(xdlclass_t *));
  87
  88        cf->alloc = size;
  89        if (!(cf->rcrecs = (xdlclass_t **) xdl_malloc(cf->alloc * sizeof(xdlclass_t *)))) {
  90
  91                xdl_free(cf->rchash);
  92                xdl_cha_free(&cf->ncha);
  93                return -1;
  94        }
  95
  96        cf->count = 0;
  97
  98        return 0;
  99}
 100
 101
 102static void xdl_free_classifier(xdlclassifier_t *cf) {
 103
 104        xdl_free(cf->rcrecs);
 105        xdl_free(cf->rchash);
 106        xdl_cha_free(&cf->ncha);
 107}
 108
 109
 110static int xdl_classify_record(unsigned int pass, xdlclassifier_t *cf, xrecord_t **rhash,
 111                               unsigned int hbits, xrecord_t *rec) {
 112        long hi;
 113        char const *line;
 114        xdlclass_t *rcrec;
 115        xdlclass_t **rcrecs;
 116
 117        line = rec->ptr;
 118        hi = (long) XDL_HASHLONG(rec->ha, cf->hbits);
 119        for (rcrec = cf->rchash[hi]; rcrec; rcrec = rcrec->next)
 120                if (rcrec->ha == rec->ha &&
 121                                xdl_recmatch(rcrec->line, rcrec->size,
 122                                        rec->ptr, rec->size, cf->flags))
 123                        break;
 124
 125        if (!rcrec) {
 126                if (!(rcrec = xdl_cha_alloc(&cf->ncha))) {
 127
 128                        return -1;
 129                }
 130                rcrec->idx = cf->count++;
 131                if (cf->count > cf->alloc) {
 132                        cf->alloc *= 2;
 133                        if (!(rcrecs = (xdlclass_t **) xdl_realloc(cf->rcrecs, cf->alloc * sizeof(xdlclass_t *)))) {
 134
 135                                return -1;
 136                        }
 137                        cf->rcrecs = rcrecs;
 138                }
 139                cf->rcrecs[rcrec->idx] = rcrec;
 140                rcrec->line = line;
 141                rcrec->size = rec->size;
 142                rcrec->ha = rec->ha;
 143                rcrec->len1 = rcrec->len2 = 0;
 144                rcrec->next = cf->rchash[hi];
 145                cf->rchash[hi] = rcrec;
 146        }
 147
 148        (pass == 1) ? rcrec->len1++ : rcrec->len2++;
 149
 150        rec->ha = (unsigned long) rcrec->idx;
 151
 152        hi = (long) XDL_HASHLONG(rec->ha, hbits);
 153        rec->next = rhash[hi];
 154        rhash[hi] = rec;
 155
 156        return 0;
 157}
 158
 159
 160static int xdl_prepare_ctx(unsigned int pass, mmfile_t *mf, long narec, xpparam_t const *xpp,
 161                           xdlclassifier_t *cf, xdfile_t *xdf) {
 162        unsigned int hbits;
 163        long nrec, hsize, bsize;
 164        unsigned long hav;
 165        char const *blk, *cur, *top, *prev;
 166        xrecord_t *crec;
 167        xrecord_t **recs, **rrecs;
 168        xrecord_t **rhash;
 169        unsigned long *ha;
 170        char *rchg;
 171        long *rindex;
 172
 173        ha = NULL;
 174        rindex = NULL;
 175        rchg = NULL;
 176        rhash = NULL;
 177        recs = NULL;
 178
 179        if (xdl_cha_init(&xdf->rcha, sizeof(xrecord_t), narec / 4 + 1) < 0)
 180                goto abort;
 181        if (!(recs = (xrecord_t **) xdl_malloc(narec * sizeof(xrecord_t *))))
 182                goto abort;
 183
 184        if (XDF_DIFF_ALG(xpp->flags) == XDF_HISTOGRAM_DIFF)
 185                hbits = hsize = 0;
 186        else {
 187                hbits = xdl_hashbits((unsigned int) narec);
 188                hsize = 1 << hbits;
 189                if (!(rhash = (xrecord_t **) xdl_malloc(hsize * sizeof(xrecord_t *))))
 190                        goto abort;
 191                memset(rhash, 0, hsize * sizeof(xrecord_t *));
 192        }
 193
 194        nrec = 0;
 195        if ((cur = blk = xdl_mmfile_first(mf, &bsize)) != NULL) {
 196                for (top = blk + bsize; cur < top; ) {
 197                        prev = cur;
 198                        hav = xdl_hash_record(&cur, top, xpp->flags);
 199                        if (nrec >= narec) {
 200                                narec *= 2;
 201                                if (!(rrecs = (xrecord_t **) xdl_realloc(recs, narec * sizeof(xrecord_t *))))
 202                                        goto abort;
 203                                recs = rrecs;
 204                        }
 205                        if (!(crec = xdl_cha_alloc(&xdf->rcha)))
 206                                goto abort;
 207                        crec->ptr = prev;
 208                        crec->size = (long) (cur - prev);
 209                        crec->ha = hav;
 210                        recs[nrec++] = crec;
 211
 212                        if ((XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF) &&
 213                            xdl_classify_record(pass, cf, rhash, hbits, crec) < 0)
 214                                goto abort;
 215                }
 216        }
 217
 218        if (!(rchg = (char *) xdl_malloc((nrec + 2) * sizeof(char))))
 219                goto abort;
 220        memset(rchg, 0, (nrec + 2) * sizeof(char));
 221
 222        if (!(rindex = (long *) xdl_malloc((nrec + 1) * sizeof(long))))
 223                goto abort;
 224        if (!(ha = (unsigned long *) xdl_malloc((nrec + 1) * sizeof(unsigned long))))
 225                goto abort;
 226
 227        xdf->nrec = nrec;
 228        xdf->recs = recs;
 229        xdf->hbits = hbits;
 230        xdf->rhash = rhash;
 231        xdf->rchg = rchg + 1;
 232        xdf->rindex = rindex;
 233        xdf->nreff = 0;
 234        xdf->ha = ha;
 235        xdf->dstart = 0;
 236        xdf->dend = nrec - 1;
 237
 238        return 0;
 239
 240abort:
 241        xdl_free(ha);
 242        xdl_free(rindex);
 243        xdl_free(rchg);
 244        xdl_free(rhash);
 245        xdl_free(recs);
 246        xdl_cha_free(&xdf->rcha);
 247        return -1;
 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, sample;
 265        xdlclassifier_t cf;
 266
 267        memset(&cf, 0, sizeof(cf));
 268
 269        /*
 270         * For histogram diff, we can afford a smaller sample size and
 271         * thus a poorer estimate of the number of lines, as the hash
 272         * table (rhash) won't be filled up/grown. The number of lines
 273         * (nrecs) will be updated correctly anyway by
 274         * xdl_prepare_ctx().
 275         */
 276        sample = (XDF_DIFF_ALG(xpp->flags) == XDF_HISTOGRAM_DIFF
 277                  ? XDL_GUESS_NLINES2 : XDL_GUESS_NLINES1);
 278
 279        enl1 = xdl_guess_lines(mf1, sample) + 1;
 280        enl2 = xdl_guess_lines(mf2, sample) + 1;
 281
 282        if (XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF &&
 283            xdl_init_classifier(&cf, enl1 + enl2 + 1, xpp->flags) < 0)
 284                return -1;
 285
 286        if (xdl_prepare_ctx(1, mf1, enl1, xpp, &cf, &xe->xdf1) < 0) {
 287
 288                xdl_free_classifier(&cf);
 289                return -1;
 290        }
 291        if (xdl_prepare_ctx(2, mf2, enl2, xpp, &cf, &xe->xdf2) < 0) {
 292
 293                xdl_free_ctx(&xe->xdf1);
 294                xdl_free_classifier(&cf);
 295                return -1;
 296        }
 297
 298        if ((XDF_DIFF_ALG(xpp->flags) != XDF_PATIENCE_DIFF) &&
 299            (XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF) &&
 300            xdl_optimize_ctxs(&cf, &xe->xdf1, &xe->xdf2) < 0) {
 301
 302                xdl_free_ctx(&xe->xdf2);
 303                xdl_free_ctx(&xe->xdf1);
 304                xdl_free_classifier(&cf);
 305                return -1;
 306        }
 307
 308        if (XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF)
 309                xdl_free_classifier(&cf);
 310
 311        return 0;
 312}
 313
 314
 315void xdl_free_env(xdfenv_t *xe) {
 316
 317        xdl_free_ctx(&xe->xdf2);
 318        xdl_free_ctx(&xe->xdf1);
 319}
 320
 321
 322static int xdl_clean_mmatch(char const *dis, long i, long s, long e) {
 323        long r, rdis0, rpdis0, rdis1, rpdis1;
 324
 325        /*
 326         * Limits the window the is examined during the similar-lines
 327         * scan. The loops below stops when dis[i - r] == 1 (line that
 328         * has no match), but there are corner cases where the loop
 329         * proceed all the way to the extremities by causing huge
 330         * performance penalties in case of big files.
 331         */
 332        if (i - s > XDL_SIMSCAN_WINDOW)
 333                s = i - XDL_SIMSCAN_WINDOW;
 334        if (e - i > XDL_SIMSCAN_WINDOW)
 335                e = i + XDL_SIMSCAN_WINDOW;
 336
 337        /*
 338         * Scans the lines before 'i' to find a run of lines that either
 339         * have no match (dis[j] == 0) or have multiple matches (dis[j] > 1).
 340         * Note that we always call this function with dis[i] > 1, so the
 341         * current line (i) is already a multimatch line.
 342         */
 343        for (r = 1, rdis0 = 0, rpdis0 = 1; (i - r) >= s; r++) {
 344                if (!dis[i - r])
 345                        rdis0++;
 346                else if (dis[i - r] == 2)
 347                        rpdis0++;
 348                else
 349                        break;
 350        }
 351        /*
 352         * If the run before the line 'i' found only multimatch lines, we
 353         * return 0 and hence we don't make the current line (i) discarded.
 354         * We want to discard multimatch lines only when they appear in the
 355         * middle of runs with nomatch lines (dis[j] == 0).
 356         */
 357        if (rdis0 == 0)
 358                return 0;
 359        for (r = 1, rdis1 = 0, rpdis1 = 1; (i + r) <= e; r++) {
 360                if (!dis[i + r])
 361                        rdis1++;
 362                else if (dis[i + r] == 2)
 363                        rpdis1++;
 364                else
 365                        break;
 366        }
 367        /*
 368         * If the run after the line 'i' found only multimatch lines, we
 369         * return 0 and hence we don't make the current line (i) discarded.
 370         */
 371        if (rdis1 == 0)
 372                return 0;
 373        rdis1 += rdis0;
 374        rpdis1 += rpdis0;
 375
 376        return rpdis1 * XDL_KPDIS_RUN < (rpdis1 + rdis1);
 377}
 378
 379
 380/*
 381 * Try to reduce the problem complexity, discard records that have no
 382 * matches on the other file. Also, lines that have multiple matches
 383 * might be potentially discarded if they happear in a run of discardable.
 384 */
 385static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2) {
 386        long i, nm, nreff, mlim;
 387        xrecord_t **recs;
 388        xdlclass_t *rcrec;
 389        char *dis, *dis1, *dis2;
 390
 391        if (!(dis = (char *) xdl_malloc(xdf1->nrec + xdf2->nrec + 2))) {
 392
 393                return -1;
 394        }
 395        memset(dis, 0, xdf1->nrec + xdf2->nrec + 2);
 396        dis1 = dis;
 397        dis2 = dis1 + xdf1->nrec + 1;
 398
 399        if ((mlim = xdl_bogosqrt(xdf1->nrec)) > XDL_MAX_EQLIMIT)
 400                mlim = XDL_MAX_EQLIMIT;
 401        for (i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart]; i <= xdf1->dend; i++, recs++) {
 402                rcrec = cf->rcrecs[(*recs)->ha];
 403                nm = rcrec ? rcrec->len2 : 0;
 404                dis1[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
 405        }
 406
 407        if ((mlim = xdl_bogosqrt(xdf2->nrec)) > XDL_MAX_EQLIMIT)
 408                mlim = XDL_MAX_EQLIMIT;
 409        for (i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart]; i <= xdf2->dend; i++, recs++) {
 410                rcrec = cf->rcrecs[(*recs)->ha];
 411                nm = rcrec ? rcrec->len1 : 0;
 412                dis2[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
 413        }
 414
 415        for (nreff = 0, i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart];
 416             i <= xdf1->dend; i++, recs++) {
 417                if (dis1[i] == 1 ||
 418                    (dis1[i] == 2 && !xdl_clean_mmatch(dis1, i, xdf1->dstart, xdf1->dend))) {
 419                        xdf1->rindex[nreff] = i;
 420                        xdf1->ha[nreff] = (*recs)->ha;
 421                        nreff++;
 422                } else
 423                        xdf1->rchg[i] = 1;
 424        }
 425        xdf1->nreff = nreff;
 426
 427        for (nreff = 0, i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart];
 428             i <= xdf2->dend; i++, recs++) {
 429                if (dis2[i] == 1 ||
 430                    (dis2[i] == 2 && !xdl_clean_mmatch(dis2, i, xdf2->dstart, xdf2->dend))) {
 431                        xdf2->rindex[nreff] = i;
 432                        xdf2->ha[nreff] = (*recs)->ha;
 433                        nreff++;
 434                } else
 435                        xdf2->rchg[i] = 1;
 436        }
 437        xdf2->nreff = nreff;
 438
 439        xdl_free(dis);
 440
 441        return 0;
 442}
 443
 444
 445/*
 446 * Early trim initial and terminal matching records.
 447 */
 448static int xdl_trim_ends(xdfile_t *xdf1, xdfile_t *xdf2) {
 449        long i, lim;
 450        xrecord_t **recs1, **recs2;
 451
 452        recs1 = xdf1->recs;
 453        recs2 = xdf2->recs;
 454        for (i = 0, lim = XDL_MIN(xdf1->nrec, xdf2->nrec); i < lim;
 455             i++, recs1++, recs2++)
 456                if ((*recs1)->ha != (*recs2)->ha)
 457                        break;
 458
 459        xdf1->dstart = xdf2->dstart = i;
 460
 461        recs1 = xdf1->recs + xdf1->nrec - 1;
 462        recs2 = xdf2->recs + xdf2->nrec - 1;
 463        for (lim -= i, i = 0; i < lim; i++, recs1--, recs2--)
 464                if ((*recs1)->ha != (*recs2)->ha)
 465                        break;
 466
 467        xdf1->dend = xdf1->nrec - i - 1;
 468        xdf2->dend = xdf2->nrec - i - 1;
 469
 470        return 0;
 471}
 472
 473
 474static int xdl_optimize_ctxs(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2) {
 475
 476        if (xdl_trim_ends(xdf1, xdf2) < 0 ||
 477            xdl_cleanup_records(cf, xdf1, xdf2) < 0) {
 478
 479                return -1;
 480        }
 481
 482        return 0;
 483}