Andrew's git / gitweb.git / xdiff/xprepare.c
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xdiff / xprepare.con commit revision.c: explain what tree_difference does (0a4ba7f)
   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
  27#define XDL_KPDIS_RUN 4
  28#define XDL_MAX_EQLIMIT 1024
  29
  30
  31
  32typedef struct s_xdlclass {
  33        struct s_xdlclass *next;
  34        unsigned long ha;
  35        char const *line;
  36        long size;
  37        long idx;
  38} xdlclass_t;
  39
  40typedef struct s_xdlclassifier {
  41        unsigned int hbits;
  42        long hsize;
  43        xdlclass_t **rchash;
  44        chastore_t ncha;
  45        long count;
  46        long flags;
  47} xdlclassifier_t;
  48
  49
  50
  51
  52static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags);
  53static void xdl_free_classifier(xdlclassifier_t *cf);
  54static int xdl_classify_record(xdlclassifier_t *cf, xrecord_t **rhash, unsigned int hbits,
  55                               xrecord_t *rec);
  56static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
  57                           xdlclassifier_t *cf, xdfile_t *xdf);
  58static void xdl_free_ctx(xdfile_t *xdf);
  59static int xdl_clean_mmatch(char const *dis, long i, long s, long e);
  60static int xdl_cleanup_records(xdfile_t *xdf1, xdfile_t *xdf2);
  61static int xdl_trim_ends(xdfile_t *xdf1, xdfile_t *xdf2);
  62static int xdl_optimize_ctxs(xdfile_t *xdf1, xdfile_t *xdf2);
  63
  64
  65
  66
  67static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags) {
  68        long i;
  69
  70        cf->flags = flags;
  71
  72        cf->hbits = xdl_hashbits((unsigned int) size);
  73        cf->hsize = 1 << cf->hbits;
  74
  75        if (xdl_cha_init(&cf->ncha, sizeof(xdlclass_t), size / 4 + 1) < 0) {
  76
  77                return -1;
  78        }
  79        if (!(cf->rchash = (xdlclass_t **) xdl_malloc(cf->hsize * sizeof(xdlclass_t *)))) {
  80
  81                xdl_cha_free(&cf->ncha);
  82                return -1;
  83        }
  84        for (i = 0; i < cf->hsize; i++)
  85                cf->rchash[i] = NULL;
  86
  87        cf->count = 0;
  88
  89        return 0;
  90}
  91
  92
  93static void xdl_free_classifier(xdlclassifier_t *cf) {
  94
  95        xdl_free(cf->rchash);
  96        xdl_cha_free(&cf->ncha);
  97}
  98
  99
 100static int xdl_classify_record(xdlclassifier_t *cf, xrecord_t **rhash, unsigned int hbits,
 101                               xrecord_t *rec) {
 102        long hi;
 103        char const *line;
 104        xdlclass_t *rcrec;
 105
 106        line = rec->ptr;
 107        hi = (long) XDL_HASHLONG(rec->ha, cf->hbits);
 108        for (rcrec = cf->rchash[hi]; rcrec; rcrec = rcrec->next)
 109                if (rcrec->ha == rec->ha &&
 110                                xdl_recmatch(rcrec->line, rcrec->size,
 111                                        rec->ptr, rec->size, cf->flags))
 112                        break;
 113
 114        if (!rcrec) {
 115                if (!(rcrec = xdl_cha_alloc(&cf->ncha))) {
 116
 117                        return -1;
 118                }
 119                rcrec->idx = cf->count++;
 120                rcrec->line = line;
 121                rcrec->size = rec->size;
 122                rcrec->ha = rec->ha;
 123                rcrec->next = cf->rchash[hi];
 124                cf->rchash[hi] = rcrec;
 125        }
 126
 127        rec->ha = (unsigned long) rcrec->idx;
 128
 129        hi = (long) XDL_HASHLONG(rec->ha, hbits);
 130        rec->next = rhash[hi];
 131        rhash[hi] = rec;
 132
 133        return 0;
 134}
 135
 136
 137static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
 138                           xdlclassifier_t *cf, xdfile_t *xdf) {
 139        unsigned int hbits;
 140        long i, nrec, hsize, bsize;
 141        unsigned long hav;
 142        char const *blk, *cur, *top, *prev;
 143        xrecord_t *crec;
 144        xrecord_t **recs, **rrecs;
 145        xrecord_t **rhash;
 146        unsigned long *ha;
 147        char *rchg;
 148        long *rindex;
 149
 150        if (xdl_cha_init(&xdf->rcha, sizeof(xrecord_t), narec / 4 + 1) < 0) {
 151
 152                return -1;
 153        }
 154        if (!(recs = (xrecord_t **) xdl_malloc(narec * sizeof(xrecord_t *)))) {
 155
 156                xdl_cha_free(&xdf->rcha);
 157                return -1;
 158        }
 159
 160        hbits = xdl_hashbits((unsigned int) narec);
 161        hsize = 1 << hbits;
 162        if (!(rhash = (xrecord_t **) xdl_malloc(hsize * sizeof(xrecord_t *)))) {
 163
 164                xdl_free(recs);
 165                xdl_cha_free(&xdf->rcha);
 166                return -1;
 167        }
 168        for (i = 0; i < hsize; i++)
 169                rhash[i] = NULL;
 170
 171        nrec = 0;
 172        if ((cur = blk = xdl_mmfile_first(mf, &bsize)) != NULL) {
 173                for (top = blk + bsize;;) {
 174                        if (cur >= top) {
 175                                if (!(cur = blk = xdl_mmfile_next(mf, &bsize)))
 176                                        break;
 177                                top = blk + bsize;
 178                        }
 179                        prev = cur;
 180                        hav = xdl_hash_record(&cur, top, xpp->flags);
 181                        if (nrec >= narec) {
 182                                narec *= 2;
 183                                if (!(rrecs = (xrecord_t **) xdl_realloc(recs, narec * sizeof(xrecord_t *)))) {
 184
 185                                        xdl_free(rhash);
 186                                        xdl_free(recs);
 187                                        xdl_cha_free(&xdf->rcha);
 188                                        return -1;
 189                                }
 190                                recs = rrecs;
 191                        }
 192                        if (!(crec = xdl_cha_alloc(&xdf->rcha))) {
 193
 194                                xdl_free(rhash);
 195                                xdl_free(recs);
 196                                xdl_cha_free(&xdf->rcha);
 197                                return -1;
 198                        }
 199                        crec->ptr = prev;
 200                        crec->size = (long) (cur - prev);
 201                        crec->ha = hav;
 202                        recs[nrec++] = crec;
 203
 204                        if (xdl_classify_record(cf, rhash, hbits, crec) < 0) {
 205
 206                                xdl_free(rhash);
 207                                xdl_free(recs);
 208                                xdl_cha_free(&xdf->rcha);
 209                                return -1;
 210                        }
 211                }
 212        }
 213
 214        if (!(rchg = (char *) xdl_malloc((nrec + 2) * sizeof(char)))) {
 215
 216                xdl_free(rhash);
 217                xdl_free(recs);
 218                xdl_cha_free(&xdf->rcha);
 219                return -1;
 220        }
 221        memset(rchg, 0, (nrec + 2) * sizeof(char));
 222
 223        if (!(rindex = (long *) xdl_malloc((nrec + 1) * sizeof(long)))) {
 224
 225                xdl_free(rchg);
 226                xdl_free(rhash);
 227                xdl_free(recs);
 228                xdl_cha_free(&xdf->rcha);
 229                return -1;
 230        }
 231        if (!(ha = (unsigned long *) xdl_malloc((nrec + 1) * sizeof(unsigned long)))) {
 232
 233                xdl_free(rindex);
 234                xdl_free(rchg);
 235                xdl_free(rhash);
 236                xdl_free(recs);
 237                xdl_cha_free(&xdf->rcha);
 238                return -1;
 239        }
 240
 241        xdf->nrec = nrec;
 242        xdf->recs = recs;
 243        xdf->hbits = hbits;
 244        xdf->rhash = rhash;
 245        xdf->rchg = rchg + 1;
 246        xdf->rindex = rindex;
 247        xdf->nreff = 0;
 248        xdf->ha = ha;
 249        xdf->dstart = 0;
 250        xdf->dend = nrec - 1;
 251
 252        return 0;
 253}
 254
 255
 256static void xdl_free_ctx(xdfile_t *xdf) {
 257
 258        xdl_free(xdf->rhash);
 259        xdl_free(xdf->rindex);
 260        xdl_free(xdf->rchg - 1);
 261        xdl_free(xdf->ha);
 262        xdl_free(xdf->recs);
 263        xdl_cha_free(&xdf->rcha);
 264}
 265
 266
 267int xdl_prepare_env(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
 268                    xdfenv_t *xe) {
 269        long enl1, enl2;
 270        xdlclassifier_t cf;
 271
 272        enl1 = xdl_guess_lines(mf1) + 1;
 273        enl2 = xdl_guess_lines(mf2) + 1;
 274
 275        if (xdl_init_classifier(&cf, enl1 + enl2 + 1, xpp->flags) < 0) {
 276
 277                return -1;
 278        }
 279
 280        if (xdl_prepare_ctx(mf1, enl1, xpp, &cf, &xe->xdf1) < 0) {
 281
 282                xdl_free_classifier(&cf);
 283                return -1;
 284        }
 285        if (xdl_prepare_ctx(mf2, enl2, xpp, &cf, &xe->xdf2) < 0) {
 286
 287                xdl_free_ctx(&xe->xdf1);
 288                xdl_free_classifier(&cf);
 289                return -1;
 290        }
 291
 292        xdl_free_classifier(&cf);
 293
 294        if (xdl_optimize_ctxs(&xe->xdf1, &xe->xdf2) < 0) {
 295
 296                xdl_free_ctx(&xe->xdf2);
 297                xdl_free_ctx(&xe->xdf1);
 298                return -1;
 299        }
 300
 301        return 0;
 302}
 303
 304
 305void xdl_free_env(xdfenv_t *xe) {
 306
 307        xdl_free_ctx(&xe->xdf2);
 308        xdl_free_ctx(&xe->xdf1);
 309}
 310
 311
 312static int xdl_clean_mmatch(char const *dis, long i, long s, long e) {
 313        long r, rdis0, rpdis0, rdis1, rpdis1;
 314
 315        /*
 316         * Scans the lines before 'i' to find a run of lines that either
 317         * have no match (dis[j] == 0) or have multiple matches (dis[j] > 1).
 318         * Note that we always call this function with dis[i] > 1, so the
 319         * current line (i) is already a multimatch line.
 320         */
 321        for (r = 1, rdis0 = 0, rpdis0 = 1; (i - r) >= s; r++) {
 322                if (!dis[i - r])
 323                        rdis0++;
 324                else if (dis[i - r] == 2)
 325                        rpdis0++;
 326                else
 327                        break;
 328        }
 329        /*
 330         * If the run before the line 'i' found only multimatch lines, we
 331         * return 0 and hence we don't make the current line (i) discarded.
 332         * We want to discard multimatch lines only when they appear in the
 333         * middle of runs with nomatch lines (dis[j] == 0).
 334         */
 335        if (rdis0 == 0)
 336                return 0;
 337        for (r = 1, rdis1 = 0, rpdis1 = 1; (i + r) <= e; r++) {
 338                if (!dis[i + r])
 339                        rdis1++;
 340                else if (dis[i + r] == 2)
 341                        rpdis1++;
 342                else
 343                        break;
 344        }
 345        /*
 346         * If the run after the line 'i' found only multimatch lines, we
 347         * return 0 and hence we don't make the current line (i) discarded.
 348         */
 349        if (rdis1 == 0)
 350                return 0;
 351        rdis1 += rdis0;
 352        rpdis1 += rpdis0;
 353
 354        return rpdis1 * XDL_KPDIS_RUN < (rpdis1 + rdis1);
 355}
 356
 357
 358/*
 359 * Try to reduce the problem complexity, discard records that have no
 360 * matches on the other file. Also, lines that have multiple matches
 361 * might be potentially discarded if they happear in a run of discardable.
 362 */
 363static int xdl_cleanup_records(xdfile_t *xdf1, xdfile_t *xdf2) {
 364        long i, nm, rhi, nreff, mlim;
 365        unsigned long hav;
 366        xrecord_t **recs;
 367        xrecord_t *rec;
 368        char *dis, *dis1, *dis2;
 369
 370        if (!(dis = (char *) xdl_malloc(xdf1->nrec + xdf2->nrec + 2))) {
 371
 372                return -1;
 373        }
 374        memset(dis, 0, xdf1->nrec + xdf2->nrec + 2);
 375        dis1 = dis;
 376        dis2 = dis1 + xdf1->nrec + 1;
 377
 378        if ((mlim = xdl_bogosqrt(xdf1->nrec)) > XDL_MAX_EQLIMIT)
 379                mlim = XDL_MAX_EQLIMIT;
 380        for (i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart]; i <= xdf1->dend; i++, recs++) {
 381                hav = (*recs)->ha;
 382                rhi = (long) XDL_HASHLONG(hav, xdf2->hbits);
 383                for (nm = 0, rec = xdf2->rhash[rhi]; rec; rec = rec->next)
 384                        if (rec->ha == hav && ++nm == mlim)
 385                                break;
 386                dis1[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
 387        }
 388
 389        if ((mlim = xdl_bogosqrt(xdf2->nrec)) > XDL_MAX_EQLIMIT)
 390                mlim = XDL_MAX_EQLIMIT;
 391        for (i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart]; i <= xdf2->dend; i++, recs++) {
 392                hav = (*recs)->ha;
 393                rhi = (long) XDL_HASHLONG(hav, xdf1->hbits);
 394                for (nm = 0, rec = xdf1->rhash[rhi]; rec; rec = rec->next)
 395                        if (rec->ha == hav && ++nm == mlim)
 396                                break;
 397                dis2[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
 398        }
 399
 400        for (nreff = 0, i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart];
 401             i <= xdf1->dend; i++, recs++) {
 402                if (dis1[i] == 1 ||
 403                    (dis1[i] == 2 && !xdl_clean_mmatch(dis1, i, xdf1->dstart, xdf1->dend))) {
 404                        xdf1->rindex[nreff] = i;
 405                        xdf1->ha[nreff] = (*recs)->ha;
 406                        nreff++;
 407                } else
 408                        xdf1->rchg[i] = 1;
 409        }
 410        xdf1->nreff = nreff;
 411
 412        for (nreff = 0, i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart];
 413             i <= xdf2->dend; i++, recs++) {
 414                if (dis2[i] == 1 ||
 415                    (dis2[i] == 2 && !xdl_clean_mmatch(dis2, i, xdf2->dstart, xdf2->dend))) {
 416                        xdf2->rindex[nreff] = i;
 417                        xdf2->ha[nreff] = (*recs)->ha;
 418                        nreff++;
 419                } else
 420                        xdf2->rchg[i] = 1;
 421        }
 422        xdf2->nreff = nreff;
 423
 424        xdl_free(dis);
 425
 426        return 0;
 427}
 428
 429
 430/*
 431 * Early trim initial and terminal matching records.
 432 */
 433static int xdl_trim_ends(xdfile_t *xdf1, xdfile_t *xdf2) {
 434        long i, lim;
 435        xrecord_t **recs1, **recs2;
 436
 437        recs1 = xdf1->recs;
 438        recs2 = xdf2->recs;
 439        for (i = 0, lim = XDL_MIN(xdf1->nrec, xdf2->nrec); i < lim;
 440             i++, recs1++, recs2++)
 441                if ((*recs1)->ha != (*recs2)->ha)
 442                        break;
 443
 444        xdf1->dstart = xdf2->dstart = i;
 445
 446        recs1 = xdf1->recs + xdf1->nrec - 1;
 447        recs2 = xdf2->recs + xdf2->nrec - 1;
 448        for (lim -= i, i = 0; i < lim; i++, recs1--, recs2--)
 449                if ((*recs1)->ha != (*recs2)->ha)
 450                        break;
 451
 452        xdf1->dend = xdf1->nrec - i - 1;
 453        xdf2->dend = xdf2->nrec - i - 1;
 454
 455        return 0;
 456}
 457
 458
 459static int xdl_optimize_ctxs(xdfile_t *xdf1, xdfile_t *xdf2) {
 460
 461        if (xdl_trim_ends(xdf1, xdf2) < 0 ||
 462            xdl_cleanup_records(xdf1, xdf2) < 0) {
 463
 464                return -1;
 465        }
 466
 467        return 0;
 468}
 469