[thirdparty/git.git] / xdiff / xprepare.c

/*
 *  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 <davidel@xmailserver.org>
 *
 */

#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 {
	struct s_xdlclass *next;
	unsigned long ha;
	char const *line;
	long size;
	long idx;
	long len1, len2;
} xdlclass_t;

typedef struct s_xdlclassifier {
	unsigned int hbits;
	long hsize;
	xdlclass_t **rchash;
	chastore_t ncha;
	xdlclass_t **rcrecs;
	long alloc;
	long count;
	long flags;
} 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 (!XDL_CALLOC_ARRAY(cf->rchash, cf->hsize)) {

		xdl_cha_free(&cf->ncha);
		return -1;
	}

	cf->alloc = size;
	if (!XDL_ALLOC_ARRAY(cf->rcrecs, cf->alloc)) {

		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;

	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 (XDL_ALLOC_GROW(cf->rcrecs, cf->count, cf->alloc))
				return -1;
		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;
	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 (!XDL_ALLOC_ARRAY(recs, narec))
		goto abort;

	hbits = xdl_hashbits((unsigned int) narec);
	hsize = 1 << hbits;
	if (!XDL_CALLOC_ARRAY(rhash, hsize))
		goto abort;

	nrec = 0;
	if ((cur = blk = xdl_mmfile_first(mf, &bsize))) {
		for (top = blk + bsize; cur < top; ) {
			prev = cur;
			hav = xdl_hash_record(&cur, top, xpp->flags);
			if (XDL_ALLOC_GROW(recs, nrec + 1, narec))
				goto abort;
			if (!(crec = xdl_cha_alloc(&xdf->rcha)))
				goto abort;
			crec->ptr = prev;
			crec->size = (long) (cur - prev);
			crec->ha = hav;
			recs[nrec++] = crec;
			if (xdl_classify_record(pass, cf, rhash, hbits, crec) < 0)
				goto abort;
		}
	}

	if (!XDL_CALLOC_ARRAY(rchg, nrec + 2))
		goto abort;

	if ((XDF_DIFF_ALG(xpp->flags) != XDF_PATIENCE_DIFF) &&
	    (XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF)) {
		if (!XDL_ALLOC_ARRAY(rindex, nrec + 1))
			goto abort;
		if (!XDL_ALLOC_ARRAY(ha, nrec + 1))
			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 (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;
	}

	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 (!XDL_CALLOC_ARRAY(dis, xdf1->nrec + xdf2->nrec + 2))
		return -1;
	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;
}
Commit	Line	Data
3443546f LT	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
48425792 TZ	16	* License along with this library; if not, see
48425792 TZ	17	* <http://www.gnu.org/licenses/>.
3443546f LT	18	*
	19	* Davide Libenzi <davidel@xmailserver.org>
	20	*
	21	*/
	22
	23	#include "xinclude.h"
	24
	25
3443546f	26	#define XDL_KPDIS_RUN 4
ca557aff	27	#define XDL_MAX_EQLIMIT 1024
9b28d554	28	#define XDL_SIMSCAN_WINDOW 100
86abba80 TRC	29	#define XDL_GUESS_NLINES1 256
86abba80 TRC	30	#define XDL_GUESS_NLINES2 20
3443546f LT	31
	32
	33	typedef struct s_xdlclass {
	34	struct s_xdlclass *next;
	35	unsigned long ha;
	36	char const *line;
	37	long size;
	38	long idx;
27af01d5	39	long len1, len2;
3443546f LT	40	} xdlclass_t;
	41
	42	typedef struct s_xdlclassifier {
	43	unsigned int hbits;
	44	long hsize;
	45	xdlclass_t **rchash;
	46	chastore_t ncha;
27af01d5 TRC	47	xdlclass_t **rcrecs;
27af01d5 TRC	48	long alloc;
3443546f	49	long count;
0d21efa5	50	long flags;
3443546f LT	51	} xdlclassifier_t;
	52
	53
	54
	55
0d21efa5	56	static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags);
3443546f	57	static void xdl_free_classifier(xdlclassifier_t *cf);
27af01d5 TRC	58	static int xdl_classify_record(unsigned int pass, xdlclassifier_t cf, xrecord_t *rhash,
	59	unsigned int hbits, xrecord_t *rec);
	60	static int xdl_prepare_ctx(unsigned int pass, mmfile_t mf, long narec, xpparam_t const xpp,
3443546f LT	61	xdlclassifier_t cf, xdfile_t xdf);
	62	static void xdl_free_ctx(xdfile_t *xdf);
	63	static int xdl_clean_mmatch(char const *dis, long i, long s, long e);
27af01d5	64	static int xdl_cleanup_records(xdlclassifier_t cf, xdfile_t xdf1, xdfile_t *xdf2);
3443546f	65	static int xdl_trim_ends(xdfile_t xdf1, xdfile_t xdf2);
27af01d5	66	static int xdl_optimize_ctxs(xdlclassifier_t cf, xdfile_t xdf1, xdfile_t *xdf2);
3443546f LT	67
	68
	69
	70
0d21efa5	71	static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags) {
0d21efa5 JS	72	cf->flags = flags;
0d21efa5 JS	73
3443546f LT	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	}
848fd5ae	81	if (!XDL_CALLOC_ARRAY(cf->rchash, cf->hsize)) {
3443546f LT	82
	83	xdl_cha_free(&cf->ncha);
	84	return -1;
	85	}
3443546f	86
27af01d5	87	cf->alloc = size;
abf04bda	88	if (!XDL_ALLOC_ARRAY(cf->rcrecs, cf->alloc)) {
27af01d5 TRC	89
	90	xdl_free(cf->rchash);
	91	xdl_cha_free(&cf->ncha);
	92	return -1;
	93	}
	94
3443546f LT	95	cf->count = 0;
	96
	97	return 0;
	98	}
	99
	100
	101	static void xdl_free_classifier(xdlclassifier_t *cf) {
	102
27af01d5	103	xdl_free(cf->rcrecs);
3443546f LT	104	xdl_free(cf->rchash);
	105	xdl_cha_free(&cf->ncha);
	106	}
	107
	108
27af01d5 TRC	109	static int xdl_classify_record(unsigned int pass, xdlclassifier_t cf, xrecord_t *rhash,
27af01d5 TRC	110	unsigned int hbits, xrecord_t *rec) {
3443546f LT	111	long hi;
	112	char const *line;
	113	xdlclass_t *rcrec;
	114
	115	line = rec->ptr;
	116	hi = (long) XDL_HASHLONG(rec->ha, cf->hbits);
	117	for (rcrec = cf->rchash[hi]; rcrec; rcrec = rcrec->next)
0d21efa5 JS	118	if (rcrec->ha == rec->ha &&
	119	xdl_recmatch(rcrec->line, rcrec->size,
	120	rec->ptr, rec->size, cf->flags))
3443546f LT	121	break;
	122
	123	if (!rcrec) {
	124	if (!(rcrec = xdl_cha_alloc(&cf->ncha))) {
	125
	126	return -1;
	127	}
	128	rcrec->idx = cf->count++;
f7b587bf	129	if (XDL_ALLOC_GROW(cf->rcrecs, cf->count, cf->alloc))
27af01d5	130	return -1;
27af01d5	131	cf->rcrecs[rcrec->idx] = rcrec;
3443546f LT	132	rcrec->line = line;
	133	rcrec->size = rec->size;
	134	rcrec->ha = rec->ha;
27af01d5	135	rcrec->len1 = rcrec->len2 = 0;
3443546f LT	136	rcrec->next = cf->rchash[hi];
	137	cf->rchash[hi] = rcrec;
	138	}
	139
27af01d5 TRC	140	(pass == 1) ? rcrec->len1++ : rcrec->len2++;
27af01d5 TRC	141
3443546f LT	142	rec->ha = (unsigned long) rcrec->idx;
	143
	144	hi = (long) XDL_HASHLONG(rec->ha, hbits);
	145	rec->next = rhash[hi];
	146	rhash[hi] = rec;
	147
	148	return 0;
	149	}
	150
	151
27af01d5	152	static int xdl_prepare_ctx(unsigned int pass, mmfile_t mf, long narec, xpparam_t const xpp,
3443546f LT	153	xdlclassifier_t cf, xdfile_t xdf) {
3443546f LT	154	unsigned int hbits;
452f4fa5	155	long nrec, hsize, bsize;
3443546f LT	156	unsigned long hav;
	157	char const blk, cur, top, prev;
	158	xrecord_t *crec;
f7b587bf	159	xrecord_t **recs;
3443546f LT	160	xrecord_t **rhash;
	161	unsigned long *ha;
	162	char *rchg;
	163	long *rindex;
	164
159607a8 TRC	165	ha = NULL;
	166	rindex = NULL;
	167	rchg = NULL;
	168	rhash = NULL;
	169	recs = NULL;
3443546f	170
159607a8 TRC	171	if (xdl_cha_init(&xdf->rcha, sizeof(xrecord_t), narec / 4 + 1) < 0)
159607a8 TRC	172	goto abort;
abf04bda	173	if (!XDL_ALLOC_ARRAY(recs, narec))
159607a8	174	goto abort;
3443546f	175
663c5ad0 PW	176	hbits = xdl_hashbits((unsigned int) narec);
663c5ad0 PW	177	hsize = 1 << hbits;
848fd5ae	178	if (!XDL_CALLOC_ARRAY(rhash, hsize))
663c5ad0	179	goto abort;
3443546f LT	180
3443546f LT	181	nrec = 0;
afe8a907	182	if ((cur = blk = xdl_mmfile_first(mf, &bsize))) {
739864b1	183	for (top = blk + bsize; cur < top; ) {
3443546f	184	prev = cur;
0d21efa5	185	hav = xdl_hash_record(&cur, top, xpp->flags);
f7b587bf PW	186	if (XDL_ALLOC_GROW(recs, nrec + 1, narec))
f7b587bf PW	187	goto abort;
159607a8 TRC	188	if (!(crec = xdl_cha_alloc(&xdf->rcha)))
159607a8 TRC	189	goto abort;
3443546f LT	190	crec->ptr = prev;
	191	crec->size = (long) (cur - prev);
	192	crec->ha = hav;
	193	recs[nrec++] = crec;
663c5ad0	194	if (xdl_classify_record(pass, cf, rhash, hbits, crec) < 0)
159607a8	195	goto abort;
3443546f LT	196	}
	197	}
	198
848fd5ae	199	if (!XDL_CALLOC_ARRAY(rchg, nrec + 2))
159607a8	200	goto abort;
3443546f	201
b82dd3f7 PW	202	if ((XDF_DIFF_ALG(xpp->flags) != XDF_PATIENCE_DIFF) &&
b82dd3f7 PW	203	(XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF)) {
abf04bda	204	if (!XDL_ALLOC_ARRAY(rindex, nrec + 1))
b82dd3f7	205	goto abort;
abf04bda	206	if (!XDL_ALLOC_ARRAY(ha, nrec + 1))
b82dd3f7 PW	207	goto abort;
b82dd3f7 PW	208	}
3443546f LT	209
	210	xdf->nrec = nrec;
	211	xdf->recs = recs;
	212	xdf->hbits = hbits;
	213	xdf->rhash = rhash;
	214	xdf->rchg = rchg + 1;
	215	xdf->rindex = rindex;
	216	xdf->nreff = 0;
	217	xdf->ha = ha;
	218	xdf->dstart = 0;
	219	xdf->dend = nrec - 1;
	220
	221	return 0;
159607a8 TRC	222
	223	abort:
	224	xdl_free(ha);
	225	xdl_free(rindex);
	226	xdl_free(rchg);
	227	xdl_free(rhash);
	228	xdl_free(recs);
	229	xdl_cha_free(&xdf->rcha);
	230	return -1;
3443546f LT	231	}
	232
	233
	234	static void xdl_free_ctx(xdfile_t *xdf) {
	235
	236	xdl_free(xdf->rhash);
	237	xdl_free(xdf->rindex);
	238	xdl_free(xdf->rchg - 1);
	239	xdl_free(xdf->ha);
	240	xdl_free(xdf->recs);
	241	xdl_cha_free(&xdf->rcha);
	242	}
	243
	244
	245	int xdl_prepare_env(mmfile_t mf1, mmfile_t mf2, xpparam_t const *xpp,
	246	xdfenv_t *xe) {
86abba80	247	long enl1, enl2, sample;
3443546f LT	248	xdlclassifier_t cf;
3443546f LT	249
2738bc3f TRC	250	memset(&cf, 0, sizeof(cf));
2738bc3f TRC	251
86abba80 TRC	252	/*
	253	* For histogram diff, we can afford a smaller sample size and
	254	* thus a poorer estimate of the number of lines, as the hash
	255	* table (rhash) won't be filled up/grown. The number of lines
	256	* (nrecs) will be updated correctly anyway by
	257	* xdl_prepare_ctx().
	258	*/
307ab20b JH	259	sample = (XDF_DIFF_ALG(xpp->flags) == XDF_HISTOGRAM_DIFF
307ab20b JH	260	? XDL_GUESS_NLINES2 : XDL_GUESS_NLINES1);
86abba80 TRC	261
	262	enl1 = xdl_guess_lines(mf1, sample) + 1;
	263	enl2 = xdl_guess_lines(mf2, sample) + 1;
3443546f	264
663c5ad0	265	if (xdl_init_classifier(&cf, enl1 + enl2 + 1, xpp->flags) < 0)
3443546f	266	return -1;
3443546f	267
27af01d5	268	if (xdl_prepare_ctx(1, mf1, enl1, xpp, &cf, &xe->xdf1) < 0) {
3443546f LT	269
	270	xdl_free_classifier(&cf);
	271	return -1;
	272	}
27af01d5	273	if (xdl_prepare_ctx(2, mf2, enl2, xpp, &cf, &xe->xdf2) < 0) {
3443546f LT	274
	275	xdl_free_ctx(&xe->xdf1);
	276	xdl_free_classifier(&cf);
	277	return -1;
	278	}
	279
307ab20b JH	280	if ((XDF_DIFF_ALG(xpp->flags) != XDF_PATIENCE_DIFF) &&
	281	(XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF) &&
	282	xdl_optimize_ctxs(&cf, &xe->xdf1, &xe->xdf2) < 0) {
3443546f LT	283
	284	xdl_free_ctx(&xe->xdf2);
	285	xdl_free_ctx(&xe->xdf1);
87f16258	286	xdl_free_classifier(&cf);
3443546f LT	287	return -1;
	288	}
	289
663c5ad0	290	xdl_free_classifier(&cf);
27af01d5	291
3443546f LT	292	return 0;
	293	}
	294
	295
	296	void xdl_free_env(xdfenv_t *xe) {
	297
	298	xdl_free_ctx(&xe->xdf2);
	299	xdl_free_ctx(&xe->xdf1);
	300	}
	301
	302
	303	static int xdl_clean_mmatch(char const *dis, long i, long s, long e) {
ca557aff DL	304	long r, rdis0, rpdis0, rdis1, rpdis1;
ca557aff DL	305
9b28d554 DL	306	/*
	307	* Limits the window the is examined during the similar-lines
	308	* scan. The loops below stops when dis[i - r] == 1 (line that
	309	* has no match), but there are corner cases where the loop
	310	* proceed all the way to the extremities by causing huge
	311	* performance penalties in case of big files.
	312	*/
	313	if (i - s > XDL_SIMSCAN_WINDOW)
	314	s = i - XDL_SIMSCAN_WINDOW;
	315	if (e - i > XDL_SIMSCAN_WINDOW)
	316	e = i + XDL_SIMSCAN_WINDOW;
	317
ca557aff DL	318	/*
	319	* Scans the lines before 'i' to find a run of lines that either
	320	* have no match (dis[j] == 0) or have multiple matches (dis[j] > 1).
	321	* Note that we always call this function with dis[i] > 1, so the
	322	* current line (i) is already a multimatch line.
	323	*/
	324	for (r = 1, rdis0 = 0, rpdis0 = 1; (i - r) >= s; r++) {
3443546f	325	if (!dis[i - r])
ca557aff	326	rdis0++;
3443546f	327	else if (dis[i - r] == 2)
ca557aff	328	rpdis0++;
3443546f LT	329	else
	330	break;
	331	}
ca557aff DL	332	/*
	333	* If the run before the line 'i' found only multimatch lines, we
	334	* return 0 and hence we don't make the current line (i) discarded.
	335	* We want to discard multimatch lines only when they appear in the
	336	* middle of runs with nomatch lines (dis[j] == 0).
	337	*/
	338	if (rdis0 == 0)
	339	return 0;
	340	for (r = 1, rdis1 = 0, rpdis1 = 1; (i + r) <= e; r++) {
3443546f	341	if (!dis[i + r])
ca557aff	342	rdis1++;
3443546f	343	else if (dis[i + r] == 2)
ca557aff	344	rpdis1++;
3443546f LT	345	else
	346	break;
	347	}
ca557aff DL	348	/*
	349	* If the run after the line 'i' found only multimatch lines, we
	350	* return 0 and hence we don't make the current line (i) discarded.
	351	*/
	352	if (rdis1 == 0)
	353	return 0;
	354	rdis1 += rdis0;
	355	rpdis1 += rpdis0;
	356
	357	return rpdis1 * XDL_KPDIS_RUN < (rpdis1 + rdis1);
3443546f LT	358	}
	359
	360
	361	/*
	362	* Try to reduce the problem complexity, discard records that have no
	363	* matches on the other file. Also, lines that have multiple matches
	364	* might be potentially discarded if they happear in a run of discardable.
	365	*/
27af01d5	366	static int xdl_cleanup_records(xdlclassifier_t cf, xdfile_t xdf1, xdfile_t *xdf2) {
c5aa9068	367	long i, nm, nreff, mlim;
3443546f	368	xrecord_t **recs;
27af01d5	369	xdlclass_t *rcrec;
3443546f LT	370	char dis, dis1, *dis2;
3443546f LT	371
848fd5ae	372	if (!XDL_CALLOC_ARRAY(dis, xdf1->nrec + xdf2->nrec + 2))
3443546f	373	return -1;
3443546f LT	374	dis1 = dis;
	375	dis2 = dis1 + xdf1->nrec + 1;
	376
c5aa9068 RS	377	if ((mlim = xdl_bogosqrt(xdf1->nrec)) > XDL_MAX_EQLIMIT)
c5aa9068 RS	378	mlim = XDL_MAX_EQLIMIT;
3443546f	379	for (i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart]; i <= xdf1->dend; i++, recs++) {
27af01d5 TRC	380	rcrec = cf->rcrecs[(*recs)->ha];
27af01d5 TRC	381	nm = rcrec ? rcrec->len2 : 0;
c5aa9068	382	dis1[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
3443546f LT	383	}
3443546f LT	384
c5aa9068 RS	385	if ((mlim = xdl_bogosqrt(xdf2->nrec)) > XDL_MAX_EQLIMIT)
c5aa9068 RS	386	mlim = XDL_MAX_EQLIMIT;
3443546f	387	for (i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart]; i <= xdf2->dend; i++, recs++) {
27af01d5 TRC	388	rcrec = cf->rcrecs[(*recs)->ha];
27af01d5 TRC	389	nm = rcrec ? rcrec->len1 : 0;
c5aa9068	390	dis2[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
3443546f LT	391	}
	392
	393	for (nreff = 0, i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart];
	394	i <= xdf1->dend; i++, recs++) {
	395	if (dis1[i] == 1 \|\|
	396	(dis1[i] == 2 && !xdl_clean_mmatch(dis1, i, xdf1->dstart, xdf1->dend))) {
	397	xdf1->rindex[nreff] = i;
	398	xdf1->ha[nreff] = (*recs)->ha;
	399	nreff++;
	400	} else
	401	xdf1->rchg[i] = 1;
	402	}
	403	xdf1->nreff = nreff;
	404
	405	for (nreff = 0, i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart];
	406	i <= xdf2->dend; i++, recs++) {
	407	if (dis2[i] == 1 \|\|
	408	(dis2[i] == 2 && !xdl_clean_mmatch(dis2, i, xdf2->dstart, xdf2->dend))) {
	409	xdf2->rindex[nreff] = i;
	410	xdf2->ha[nreff] = (*recs)->ha;
	411	nreff++;
	412	} else
	413	xdf2->rchg[i] = 1;
	414	}
	415	xdf2->nreff = nreff;
	416
	417	xdl_free(dis);
	418
	419	return 0;
	420	}
	421
	422
	423	/*
	424	* Early trim initial and terminal matching records.
	425	*/
	426	static int xdl_trim_ends(xdfile_t xdf1, xdfile_t xdf2) {
	427	long i, lim;
	428	xrecord_t recs1, recs2;
	429
	430	recs1 = xdf1->recs;
	431	recs2 = xdf2->recs;
	432	for (i = 0, lim = XDL_MIN(xdf1->nrec, xdf2->nrec); i < lim;
	433	i++, recs1++, recs2++)
	434	if ((recs1)->ha != (recs2)->ha)
	435	break;
	436
	437	xdf1->dstart = xdf2->dstart = i;
	438
	439	recs1 = xdf1->recs + xdf1->nrec - 1;
	440	recs2 = xdf2->recs + xdf2->nrec - 1;
	441	for (lim -= i, i = 0; i < lim; i++, recs1--, recs2--)
	442	if ((recs1)->ha != (recs2)->ha)
	443	break;
	444
	445	xdf1->dend = xdf1->nrec - i - 1;
	446	xdf2->dend = xdf2->nrec - i - 1;
	447
	448	return 0;
	449	}
	450
	451
27af01d5	452	static int xdl_optimize_ctxs(xdlclassifier_t cf, xdfile_t xdf1, xdfile_t *xdf2) {
3443546f LT	453
3443546f LT	454	if (xdl_trim_ends(xdf1, xdf2) < 0 \|\|
27af01d5	455	xdl_cleanup_records(cf, xdf1, xdf2) < 0) {
3443546f LT	456
	457	return -1;
	458	}
	459
	460	return 0;
	461	}