/*

* LibXDiff by Davide Libenzi ( File Differential Library )

* Copyright (C) 2003 Davide Libenzi

*

* This library is free software; you can redistribute it and/or

* modify it under the terms of the GNU Lesser General Public

* License as published by the Free Software Foundation; either

* version 2.1 of the License, or (at your option) any later version.

*

* This library is distributed in the hope that it will be useful,

* but WITHOUT ANY WARRANTY; without even the implied warranty of

* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

* Lesser General Public License for more details.

*

* You should have received a copy of the GNU Lesser General Public

* License along with this library; if not, see

* <http://www.gnu.org/licenses/>.

*

* Davide Libenzi <[email protected]>

*

*/

#include "xinclude.h"

#define XDL_KPDIS_RUN 4

#define XDL_MAX_EQLIMIT 1024

#define XDL_SIMSCAN_WINDOW 100

#define XDL_GUESS_NLINES1 256

#define XDL_GUESS_NLINES2 20

typedef struct s_xdlclass {

} xdlclass_t;

typedef struct s_xdlclassifier {

} xdlclassifier_t;

static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags);

static void xdl_free_classifier(xdlclassifier_t *cf);

static int xdl_classify_record(unsigned int pass, xdlclassifier_t *cf, xrecord_t **rhash,

unsigned int hbits, xrecord_t *rec);

static int xdl_prepare_ctx(unsigned int pass, mmfile_t *mf, long narec, xpparam_t const *xpp,

xdlclassifier_t *cf, xdfile_t *xdf);

static void xdl_free_ctx(xdfile_t *xdf);

static int xdl_clean_mmatch(char const *dis, long i, long s, long e);

static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2);

static int xdl_trim_ends(xdfile_t *xdf1, xdfile_t *xdf2);

static int xdl_optimize_ctxs(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2);

static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags) {

cf->flags = flags;

cf->hbits = xdl_hashbits((unsigned int) size);

cf->hsize = 1 << cf->hbits;

if (xdl_cha_init(&cf->ncha, sizeof(xdlclass_t), size / 4 + 1) < 0) {

return -1;

}

if (!(cf->rchash = (xdlclass_t **) xdl_malloc(cf->hsize * sizeof(xdlclass_t *)))) {

xdl_cha_free(&cf->ncha);

return -1;

}

memset(cf->rchash, 0, cf->hsize * sizeof(xdlclass_t *));

cf->alloc = size;

if (!(cf->rcrecs = (xdlclass_t **) xdl_malloc(cf->alloc * sizeof(xdlclass_t *)))) {

xdl_free(cf->rchash);

xdl_cha_free(&cf->ncha);

return -1;

}

cf->count = 0;

return 0;

}

static void xdl_free_classifier(xdlclassifier_t *cf) {

xdl_free(cf->rcrecs);

xdl_free(cf->rchash);

xdl_cha_free(&cf->ncha);

}

static int xdl_classify_record(unsigned int pass, xdlclassifier_t *cf, xrecord_t **rhash,

unsigned int hbits, xrecord_t *rec) {

long hi;

char const *line;

xdlclass_t *rcrec;

xdlclass_t **rcrecs;

line = rec->ptr;

hi = (long) XDL_HASHLONG(rec->ha, cf->hbits);

for (rcrec = cf->rchash[hi]; rcrec; rcrec = rcrec->next)

if (rcrec->ha == rec->ha &&

xdl_recmatch(rcrec->line, rcrec->size,

rec->ptr, rec->size, cf->flags))

break;

if (!rcrec) {

if (!(rcrec = xdl_cha_alloc(&cf->ncha))) {

return -1;

}

rcrec->idx = cf->count++;

if (cf->count > cf->alloc) {

cf->alloc *= 2;

if (!(rcrecs = (xdlclass_t **) xdl_realloc(cf->rcrecs, cf->alloc * sizeof(xdlclass_t *)))) {

return -1;

}

cf->rcrecs = rcrecs;

}

cf->rcrecs[rcrec->idx] = rcrec;

rcrec->line = line;

rcrec->size = rec->size;

rcrec->ha = rec->ha;

rcrec->len1 = rcrec->len2 = 0;

rcrec->next = cf->rchash[hi];

cf->rchash[hi] = rcrec;

}

(pass == 1) ? rcrec->len1++ : rcrec->len2++;

rec->ha = (unsigned long) rcrec->idx;

hi = (long) XDL_HASHLONG(rec->ha, hbits);

rec->next = rhash[hi];

rhash[hi] = rec;

return 0;

}

static int xdl_prepare_ctx(unsigned int pass, mmfile_t *mf, long narec, xpparam_t const *xpp,

xdlclassifier_t *cf, xdfile_t *xdf) {

unsigned int hbits;

long nrec, hsize, bsize;

unsigned long hav;

char const *blk, *cur, *top, *prev;

xrecord_t *crec;

xrecord_t **recs, **rrecs;

xrecord_t **rhash;

unsigned long *ha;

char *rchg;

long *rindex;

ha = NULL;

rindex = NULL;

rchg = NULL;

rhash = NULL;

recs = NULL;

if (xdl_cha_init(&xdf->rcha, sizeof(xrecord_t), narec / 4 + 1) < 0)

goto abort;

if (!(recs = (xrecord_t **) xdl_malloc(narec * sizeof(xrecord_t *))))

goto abort;

if (XDF_DIFF_ALG(xpp->flags) == XDF_HISTOGRAM_DIFF)

hbits = hsize = 0;

else {

hbits = xdl_hashbits((unsigned int) narec);

hsize = 1 << hbits;

if (!(rhash = (xrecord_t **) xdl_malloc(hsize * sizeof(xrecord_t *))))

goto abort;

memset(rhash, 0, hsize * sizeof(xrecord_t *));

}

nrec = 0;

if ((cur = blk = xdl_mmfile_first(mf, &bsize)) != NULL) {

for (top = blk + bsize; cur < top; ) {

prev = cur;

hav = xdl_hash_record(&cur, top, xpp->flags);

if (nrec >= narec) {

narec *= 2;

if (!(rrecs = (xrecord_t **) xdl_realloc(recs, narec * sizeof(xrecord_t *))))

goto abort;

recs = rrecs;

}

if (!(crec = xdl_cha_alloc(&xdf->rcha)))

goto abort;

crec->ptr = prev;

crec->size = (long) (cur - prev);

crec->ha = hav;

recs[nrec++] = crec;

if ((XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF) &&

xdl_classify_record(pass, cf, rhash, hbits, crec) < 0)

goto abort;

}

}

if (!(rchg = (char *) xdl_malloc((nrec + 2) * sizeof(char))))

goto abort;

memset(rchg, 0, (nrec + 2) * sizeof(char));

if (!(rindex = (long *) xdl_malloc((nrec + 1) * sizeof(long))))

goto abort;

if (!(ha = (unsigned long *) xdl_malloc((nrec + 1) * sizeof(unsigned long))))

goto abort;

xdf->nrec = nrec;

xdf->recs = recs;

xdf->hbits = hbits;

xdf->rhash = rhash;

xdf->rchg = rchg + 1;

xdf->rindex = rindex;

xdf->nreff = 0;

xdf->ha = ha;

xdf->dstart = 0;

xdf->dend = nrec - 1;

return 0;

abort:

xdl_free(ha);

xdl_free(rindex);

xdl_free(rchg);

xdl_free(rhash);

xdl_free(recs);

xdl_cha_free(&xdf->rcha);

return -1;

}

static void xdl_free_ctx(xdfile_t *xdf) {

xdl_free(xdf->rhash);

xdl_free(xdf->rindex);

xdl_free(xdf->rchg - 1);

xdl_free(xdf->ha);

xdl_free(xdf->recs);

xdl_cha_free(&xdf->rcha);

}

int xdl_prepare_env(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,

xdfenv_t *xe) {

long enl1, enl2, sample;

xdlclassifier_t cf;

memset(&cf, 0, sizeof(cf));

/*

* For histogram diff, we can afford a smaller sample size and

* thus a poorer estimate of the number of lines, as the hash

* table (rhash) won't be filled up/grown. The number of lines

* (nrecs) will be updated correctly anyway by

* xdl_prepare_ctx().

*/

sample = (XDF_DIFF_ALG(xpp->flags) == XDF_HISTOGRAM_DIFF

? XDL_GUESS_NLINES2 : XDL_GUESS_NLINES1);

enl1 = xdl_guess_lines(mf1, sample) + 1;

enl2 = xdl_guess_lines(mf2, sample) + 1;

if (XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF &&

xdl_init_classifier(&cf, enl1 + enl2 + 1, xpp->flags) < 0)

return -1;

if (xdl_prepare_ctx(1, mf1, enl1, xpp, &cf, &xe->xdf1) < 0) {

xdl_free_classifier(&cf);

return -1;

}

if (xdl_prepare_ctx(2, mf2, enl2, xpp, &cf, &xe->xdf2) < 0) {

xdl_free_ctx(&xe->xdf1);

xdl_free_classifier(&cf);

return -1;

}

if ((XDF_DIFF_ALG(xpp->flags) != XDF_PATIENCE_DIFF) &&

(XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF) &&

xdl_optimize_ctxs(&cf, &xe->xdf1, &xe->xdf2) < 0) {

xdl_free_ctx(&xe->xdf2);

xdl_free_ctx(&xe->xdf1);

xdl_free_classifier(&cf);

return -1;

}

if (XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF)

xdl_free_classifier(&cf);

return 0;

}

void xdl_free_env(xdfenv_t *xe) {

xdl_free_ctx(&xe->xdf2);

xdl_free_ctx(&xe->xdf1);

}

static int xdl_clean_mmatch(char const *dis, long i, long s, long e) {

long r, rdis0, rpdis0, rdis1, rpdis1;

/*

* Limits the window the is examined during the similar-lines

* scan. The loops below stops when dis[i - r] == 1 (line that

* has no match), but there are corner cases where the loop

* proceed all the way to the extremities by causing huge

* performance penalties in case of big files.

*/

if (i - s > XDL_SIMSCAN_WINDOW)

s = i - XDL_SIMSCAN_WINDOW;

if (e - i > XDL_SIMSCAN_WINDOW)

e = i + XDL_SIMSCAN_WINDOW;

/*

* Scans the lines before 'i' to find a run of lines that either

* have no match (dis[j] == 0) or have multiple matches (dis[j] > 1).

* Note that we always call this function with dis[i] > 1, so the

* current line (i) is already a multimatch line.

*/

for (r = 1, rdis0 = 0, rpdis0 = 1; (i - r) >= s; r++) {

if (!dis[i - r])

rdis0++;

else if (dis[i - r] == 2)

rpdis0++;

else

break;

}

/*

* If the run before the line 'i' found only multimatch lines, we

* return 0 and hence we don't make the current line (i) discarded.

* We want to discard multimatch lines only when they appear in the

* middle of runs with nomatch lines (dis[j] == 0).

*/

if (rdis0 == 0)

return 0;

for (r = 1, rdis1 = 0, rpdis1 = 1; (i + r) <= e; r++) {

if (!dis[i + r])

rdis1++;

else if (dis[i + r] == 2)

rpdis1++;

else

break;

}

/*

* If the run after the line 'i' found only multimatch lines, we

* return 0 and hence we don't make the current line (i) discarded.

*/

if (rdis1 == 0)

return 0;

rdis1 += rdis0;

rpdis1 += rpdis0;

return rpdis1 * XDL_KPDIS_RUN < (rpdis1 + rdis1);

}

/*

* Try to reduce the problem complexity, discard records that have no

* matches on the other file. Also, lines that have multiple matches

* might be potentially discarded if they happear in a run of discardable.

*/

static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2) {

long i, nm, nreff, mlim;

xrecord_t **recs;

xdlclass_t *rcrec;

char *dis, *dis1, *dis2;

if (!(dis = (char *) xdl_malloc(xdf1->nrec + xdf2->nrec + 2))) {

return -1;

}

memset(dis, 0, xdf1->nrec + xdf2->nrec + 2);

dis1 = dis;

dis2 = dis1 + xdf1->nrec + 1;

if ((mlim = xdl_bogosqrt(xdf1->nrec)) > XDL_MAX_EQLIMIT)

mlim = XDL_MAX_EQLIMIT;

for (i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart]; i <= xdf1->dend; i++, recs++) {

rcrec = cf->rcrecs[(*recs)->ha];

nm = rcrec ? rcrec->len2 : 0;

dis1[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;

}

if ((mlim = xdl_bogosqrt(xdf2->nrec)) > XDL_MAX_EQLIMIT)

mlim = XDL_MAX_EQLIMIT;

for (i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart]; i <= xdf2->dend; i++, recs++) {

rcrec = cf->rcrecs[(*recs)->ha];

nm = rcrec ? rcrec->len1 : 0;

dis2[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;

}

for (nreff = 0, i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart];

i <= xdf1->dend; i++, recs++) {

if (dis1[i] == 1 ||

(dis1[i] == 2 && !xdl_clean_mmatch(dis1, i, xdf1->dstart, xdf1->dend))) {

xdf1->rindex[nreff] = i;

xdf1->ha[nreff] = (*recs)->ha;

nreff++;

} else

xdf1->rchg[i] = 1;

}

xdf1->nreff = nreff;

for (nreff = 0, i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart];

i <= xdf2->dend; i++, recs++) {

if (dis2[i] == 1 ||

(dis2[i] == 2 && !xdl_clean_mmatch(dis2, i, xdf2->dstart, xdf2->dend))) {

xdf2->rindex[nreff] = i;

xdf2->ha[nreff] = (*recs)->ha;

nreff++;

} else

xdf2->rchg[i] = 1;

}

xdf2->nreff = nreff;

xdl_free(dis);

return 0;

}

/*

* Early trim initial and terminal matching records.

*/

static int xdl_trim_ends(xdfile_t *xdf1, xdfile_t *xdf2) {

long i, lim;

xrecord_t **recs1, **recs2;

recs1 = xdf1->recs;

recs2 = xdf2->recs;

for (i = 0, lim = XDL_MIN(xdf1->nrec, xdf2->nrec); i < lim;

i++, recs1++, recs2++)

if ((*recs1)->ha != (*recs2)->ha)

break;

xdf1->dstart = xdf2->dstart = i;

recs1 = xdf1->recs + xdf1->nrec - 1;

recs2 = xdf2->recs + xdf2->nrec - 1;

for (lim -= i, i = 0; i < lim; i++, recs1--, recs2--)

if ((*recs1)->ha != (*recs2)->ha)

break;

xdf1->dend = xdf1->nrec - i - 1;

xdf2->dend = xdf2->nrec - i - 1;

return 0;

}

static int xdl_optimize_ctxs(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2) {

if (xdl_trim_ends(xdf1, xdf2) < 0 ||

xdl_cleanup_records(cf, xdf1, xdf2) < 0) {

return -1;

}

return 0;

}