[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, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *  Davide Libenzi <davidel@xmailserver.org>
 *
 */

#include "xinclude.h"


#define XDL_KPDIS_RUN 4
#define XDL_MAX_EQLIMIT 1024
#define XDL_SIMSCAN_WINDOW 100


typedef struct s_xdlclass {
	struct s_xdlclass *next;
	unsigned long ha;
	char const *line;
	long size;
	long idx;
} xdlclass_t;

typedef struct s_xdlclassifier {
	unsigned int hbits;
	long hsize;
	xdlclass_t **rchash;
	chastore_t ncha;
	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(xdlclassifier_t *cf, xrecord_t **rhash, unsigned int hbits,
			       xrecord_t *rec);
static int xdl_prepare_ctx(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(xdfile_t *xdf1, xdfile_t *xdf2);
static int xdl_trim_ends(xdfile_t *xdf1, xdfile_t *xdf2);
static int xdl_optimize_ctxs(xdfile_t *xdf1, xdfile_t *xdf2);


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

	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;
	}
	for (i = 0; i < cf->hsize; i++)
		cf->rchash[i] = NULL;

	cf->count = 0;

	return 0;
}


static void xdl_free_classifier(xdlclassifier_t *cf) {

	xdl_free(cf->rchash);
	xdl_cha_free(&cf->ncha);
}


static int xdl_classify_record(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++;
		rcrec->line = line;
		rcrec->size = rec->size;
		rcrec->ha = rec->ha;
		rcrec->next = cf->rchash[hi];
		cf->rchash[hi] = rcrec;
	}

	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(mmfile_t *mf, long narec, xpparam_t const *xpp,
			   xdlclassifier_t *cf, xdfile_t *xdf) {
	unsigned int hbits;
	long i, 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;

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

		return -1;
	}
	if (!(recs = (xrecord_t **) xdl_malloc(narec * sizeof(xrecord_t *)))) {

		xdl_cha_free(&xdf->rcha);
		return -1;
	}

	hbits = xdl_hashbits((unsigned int) narec);
	hsize = 1 << hbits;
	if (!(rhash = (xrecord_t **) xdl_malloc(hsize * sizeof(xrecord_t *)))) {

		xdl_free(recs);
		xdl_cha_free(&xdf->rcha);
		return -1;
	}
	for (i = 0; i < hsize; i++)
		rhash[i] = NULL;

	nrec = 0;
	if ((cur = blk = xdl_mmfile_first(mf, &bsize)) != NULL) {
		for (top = blk + bsize;;) {
			if (cur >= top) {
				if (!(cur = blk = xdl_mmfile_next(mf, &bsize)))
					break;
				top = blk + bsize;
			}
			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 *)))) {

					xdl_free(rhash);
					xdl_free(recs);
					xdl_cha_free(&xdf->rcha);
					return -1;
				}
				recs = rrecs;
			}
			if (!(crec = xdl_cha_alloc(&xdf->rcha))) {

				xdl_free(rhash);
				xdl_free(recs);
				xdl_cha_free(&xdf->rcha);
				return -1;
			}
			crec->ptr = prev;
			crec->size = (long) (cur - prev);
			crec->ha = hav;
			recs[nrec++] = crec;

			if (xdl_classify_record(cf, rhash, hbits, crec) < 0) {

				xdl_free(rhash);
				xdl_free(recs);
				xdl_cha_free(&xdf->rcha);
				return -1;
			}
		}
	}

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

		xdl_free(rhash);
		xdl_free(recs);
		xdl_cha_free(&xdf->rcha);
		return -1;
	}
	memset(rchg, 0, (nrec + 2) * sizeof(char));

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

		xdl_free(rchg);
		xdl_free(rhash);
		xdl_free(recs);
		xdl_cha_free(&xdf->rcha);
		return -1;
	}
	if (!(ha = (unsigned long *) xdl_malloc((nrec + 1) * sizeof(unsigned long)))) {

		xdl_free(rindex);
		xdl_free(rchg);
		xdl_free(rhash);
		xdl_free(recs);
		xdl_cha_free(&xdf->rcha);
		return -1;
	}

	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;
}


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;
	xdlclassifier_t cf;

	enl1 = xdl_guess_lines(mf1) + 1;
	enl2 = xdl_guess_lines(mf2) + 1;

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

		return -1;
	}

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

		xdl_free_classifier(&cf);
		return -1;
	}
	if (xdl_prepare_ctx(mf2, enl2, xpp, &cf, &xe->xdf2) < 0) {

		xdl_free_ctx(&xe->xdf1);
		xdl_free_classifier(&cf);
		return -1;
	}

	xdl_free_classifier(&cf);

	if (!(xpp->flags & XDF_PATIENCE_DIFF) &&
			xdl_optimize_ctxs(&xe->xdf1, &xe->xdf2) < 0) {

		xdl_free_ctx(&xe->xdf2);
		xdl_free_ctx(&xe->xdf1);
		return -1;
	}

	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(xdfile_t *xdf1, xdfile_t *xdf2) {
	long i, nm, rhi, nreff, mlim;
	unsigned long hav;
	xrecord_t **recs;
	xrecord_t *rec;
	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++) {
		hav = (*recs)->ha;
		rhi = (long) XDL_HASHLONG(hav, xdf2->hbits);
		for (nm = 0, rec = xdf2->rhash[rhi]; rec; rec = rec->next)
			if (rec->ha == hav && ++nm == mlim)
				break;
		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++) {
		hav = (*recs)->ha;
		rhi = (long) XDL_HASHLONG(hav, xdf1->hbits);
		for (nm = 0, rec = xdf1->rhash[rhi]; rec; rec = rec->next)
			if (rec->ha == hav && ++nm == mlim)
				break;
		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(xdfile_t *xdf1, xdfile_t *xdf2) {

	if (xdl_trim_ends(xdf1, xdf2) < 0 ||
	    xdl_cleanup_records(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
	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
3443546f	26	#define XDL_KPDIS_RUN 4
ca557aff	27	#define XDL_MAX_EQLIMIT 1024
9b28d554	28	#define XDL_SIMSCAN_WINDOW 100
3443546f LT	29
	30
	31	typedef 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
	39	typedef struct s_xdlclassifier {
	40	unsigned int hbits;
	41	long hsize;
	42	xdlclass_t **rchash;
	43	chastore_t ncha;
	44	long count;
0d21efa5	45	long flags;
3443546f LT	46	} xdlclassifier_t;
	47
	48
	49
	50
0d21efa5	51	static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags);
3443546f LT	52	static void xdl_free_classifier(xdlclassifier_t *cf);
	53	static int xdl_classify_record(xdlclassifier_t cf, xrecord_t *rhash, unsigned int hbits,
	54	xrecord_t *rec);
	55	static int xdl_prepare_ctx(mmfile_t mf, long narec, xpparam_t const xpp,
	56	xdlclassifier_t cf, xdfile_t xdf);
	57	static void xdl_free_ctx(xdfile_t *xdf);
	58	static int xdl_clean_mmatch(char const *dis, long i, long s, long e);
	59	static int xdl_cleanup_records(xdfile_t xdf1, xdfile_t xdf2);
	60	static int xdl_trim_ends(xdfile_t xdf1, xdfile_t xdf2);
	61	static int xdl_optimize_ctxs(xdfile_t xdf1, xdfile_t xdf2);
	62
	63
	64
	65
0d21efa5	66	static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags) {
3443546f LT	67	long i;
3443546f LT	68
0d21efa5 JS	69	cf->flags = flags;
0d21efa5 JS	70
3443546f LT	71	cf->hbits = xdl_hashbits((unsigned int) size);
	72	cf->hsize = 1 << cf->hbits;
	73
	74	if (xdl_cha_init(&cf->ncha, sizeof(xdlclass_t), size / 4 + 1) < 0) {
	75
	76	return -1;
	77	}
	78	if (!(cf->rchash = (xdlclass_t *) xdl_malloc(cf->hsize sizeof(xdlclass_t *)))) {
	79
	80	xdl_cha_free(&cf->ncha);
	81	return -1;
	82	}
	83	for (i = 0; i < cf->hsize; i++)
	84	cf->rchash[i] = NULL;
	85
	86	cf->count = 0;
	87
	88	return 0;
	89	}
	90
	91
	92	static void xdl_free_classifier(xdlclassifier_t *cf) {
	93
	94	xdl_free(cf->rchash);
	95	xdl_cha_free(&cf->ncha);
	96	}
	97
	98
	99	static int xdl_classify_record(xdlclassifier_t cf, xrecord_t *rhash, unsigned int hbits,
	100	xrecord_t *rec) {
	101	long hi;
	102	char const *line;
	103	xdlclass_t *rcrec;
	104
	105	line = rec->ptr;
	106	hi = (long) XDL_HASHLONG(rec->ha, cf->hbits);
	107	for (rcrec = cf->rchash[hi]; rcrec; rcrec = rcrec->next)
0d21efa5 JS	108	if (rcrec->ha == rec->ha &&
	109	xdl_recmatch(rcrec->line, rcrec->size,
	110	rec->ptr, rec->size, cf->flags))
3443546f LT	111	break;
	112
	113	if (!rcrec) {
	114	if (!(rcrec = xdl_cha_alloc(&cf->ncha))) {
	115
	116	return -1;
	117	}
	118	rcrec->idx = cf->count++;
	119	rcrec->line = line;
	120	rcrec->size = rec->size;
	121	rcrec->ha = rec->ha;
	122	rcrec->next = cf->rchash[hi];
	123	cf->rchash[hi] = rcrec;
	124	}
	125
	126	rec->ha = (unsigned long) rcrec->idx;
	127
	128	hi = (long) XDL_HASHLONG(rec->ha, hbits);
	129	rec->next = rhash[hi];
	130	rhash[hi] = rec;
	131
	132	return 0;
	133	}
	134
	135
	136	static int xdl_prepare_ctx(mmfile_t mf, long narec, xpparam_t const xpp,
	137	xdlclassifier_t cf, xdfile_t xdf) {
	138	unsigned int hbits;
	139	long i, nrec, hsize, bsize;
	140	unsigned long hav;
	141	char const blk, cur, top, prev;
	142	xrecord_t *crec;
	143	xrecord_t recs, rrecs;
	144	xrecord_t **rhash;
	145	unsigned long *ha;
	146	char *rchg;
	147	long *rindex;
	148
	149	if (xdl_cha_init(&xdf->rcha, sizeof(xrecord_t), narec / 4 + 1) < 0) {
	150
	151	return -1;
	152	}
	153	if (!(recs = (xrecord_t *) xdl_malloc(narec sizeof(xrecord_t *)))) {
	154
	155	xdl_cha_free(&xdf->rcha);
	156	return -1;
	157	}
	158
	159	hbits = xdl_hashbits((unsigned int) narec);
	160	hsize = 1 << hbits;
	161	if (!(rhash = (xrecord_t *) xdl_malloc(hsize sizeof(xrecord_t *)))) {
	162
	163	xdl_free(recs);
	164	xdl_cha_free(&xdf->rcha);
	165	return -1;
	166	}
	167	for (i = 0; i < hsize; i++)
	168	rhash[i] = NULL;
	169
	170	nrec = 0;
	171	if ((cur = blk = xdl_mmfile_first(mf, &bsize)) != NULL) {
	172	for (top = blk + bsize;;) {
	173	if (cur >= top) {
	174	if (!(cur = blk = xdl_mmfile_next(mf, &bsize)))
175	break;
176	top = blk + bsize;
177	}
178	prev = cur;
0d21efa5	179	hav = xdl_hash_record(&cur, top, xpp->flags);
3443546f LT	180	if (nrec >= narec) {
	181	narec *= 2;
	182	if (!(rrecs = (xrecord_t *) xdl_realloc(recs, narec sizeof(xrecord_t *)))) {
	183
	184	xdl_free(rhash);
	185	xdl_free(recs);
	186	xdl_cha_free(&xdf->rcha);
	187	return -1;
	188	}
	189	recs = rrecs;
	190	}
	191	if (!(crec = xdl_cha_alloc(&xdf->rcha))) {
	192
	193	xdl_free(rhash);
	194	xdl_free(recs);
	195	xdl_cha_free(&xdf->rcha);
	196	return -1;
	197	}
	198	crec->ptr = prev;
	199	crec->size = (long) (cur - prev);
	200	crec->ha = hav;
	201	recs[nrec++] = crec;
	202
	203	if (xdl_classify_record(cf, rhash, hbits, crec) < 0) {
	204
	205	xdl_free(rhash);
	206	xdl_free(recs);
	207	xdl_cha_free(&xdf->rcha);
	208	return -1;
	209	}
	210	}
	211	}
	212
	213	if (!(rchg = (char ) xdl_malloc((nrec + 2) sizeof(char)))) {
	214
	215	xdl_free(rhash);
	216	xdl_free(recs);
	217	xdl_cha_free(&xdf->rcha);
	218	return -1;
	219	}
	220	memset(rchg, 0, (nrec + 2) * sizeof(char));
	221
	222	if (!(rindex = (long ) xdl_malloc((nrec + 1) sizeof(long)))) {
	223
	224	xdl_free(rchg);
	225	xdl_free(rhash);
	226	xdl_free(recs);
	227	xdl_cha_free(&xdf->rcha);
	228	return -1;
	229	}
	230	if (!(ha = (unsigned long ) xdl_malloc((nrec + 1) sizeof(unsigned long)))) {
	231
	232	xdl_free(rindex);
	233	xdl_free(rchg);
	234	xdl_free(rhash);
	235	xdl_free(recs);
	236	xdl_cha_free(&xdf->rcha);
	237	return -1;
	238	}
	239
	240	xdf->nrec = nrec;
	241	xdf->recs = recs;
	242	xdf->hbits = hbits;
	243	xdf->rhash = rhash;
244	xdf->rchg = rchg + 1;
245	xdf->rindex = rindex;
246	xdf->nreff = 0;
247	xdf->ha = ha;
248	xdf->dstart = 0;
249	xdf->dend = nrec - 1;
250
251	return 0;
252	}
253
254
255	static void xdl_free_ctx(xdfile_t *xdf) {
256
257	xdl_free(xdf->rhash);
258	xdl_free(xdf->rindex);
259	xdl_free(xdf->rchg - 1);
260	xdl_free(xdf->ha);
261	xdl_free(xdf->recs);
262	xdl_cha_free(&xdf->rcha);
263	}
264
265
266	int xdl_prepare_env(mmfile_t mf1, mmfile_t mf2, xpparam_t const *xpp,
267	xdfenv_t *xe) {
268	long enl1, enl2;
269	xdlclassifier_t cf;
270
271	enl1 = xdl_guess_lines(mf1) + 1;
272	enl2 = xdl_guess_lines(mf2) + 1;
273
0d21efa5	274	if (xdl_init_classifier(&cf, enl1 + enl2 + 1, xpp->flags) < 0) {
3443546f LT	275
	276	return -1;
	277	}
	278
	279	if (xdl_prepare_ctx(mf1, enl1, xpp, &cf, &xe->xdf1) < 0) {
	280
	281	xdl_free_classifier(&cf);
	282	return -1;
	283	}
	284	if (xdl_prepare_ctx(mf2, enl2, xpp, &cf, &xe->xdf2) < 0) {
	285
	286	xdl_free_ctx(&xe->xdf1);
	287	xdl_free_classifier(&cf);
	288	return -1;
	289	}
	290
	291	xdl_free_classifier(&cf);
	292
92b7de93 JS	293	if (!(xpp->flags & XDF_PATIENCE_DIFF) &&
92b7de93 JS	294	xdl_optimize_ctxs(&xe->xdf1, &xe->xdf2) < 0) {
3443546f LT	295
	296	xdl_free_ctx(&xe->xdf2);
	297	xdl_free_ctx(&xe->xdf1);
	298	return -1;
	299	}
	300
	301	return 0;
	302	}
	303
	304
	305	void xdl_free_env(xdfenv_t *xe) {
	306
	307	xdl_free_ctx(&xe->xdf2);
	308	xdl_free_ctx(&xe->xdf1);
	309	}
	310
	311
	312	static int xdl_clean_mmatch(char const *dis, long i, long s, long e) {
ca557aff DL	313	long r, rdis0, rpdis0, rdis1, rpdis1;
ca557aff DL	314
9b28d554 DL	315	/*
	316	* Limits the window the is examined during the similar-lines
	317	* scan. The loops below stops when dis[i - r] == 1 (line that
	318	* has no match), but there are corner cases where the loop
	319	* proceed all the way to the extremities by causing huge
	320	* performance penalties in case of big files.
	321	*/
	322	if (i - s > XDL_SIMSCAN_WINDOW)
	323	s = i - XDL_SIMSCAN_WINDOW;
	324	if (e - i > XDL_SIMSCAN_WINDOW)
	325	e = i + XDL_SIMSCAN_WINDOW;
	326
ca557aff DL	327	/*
	328	* Scans the lines before 'i' to find a run of lines that either
	329	* have no match (dis[j] == 0) or have multiple matches (dis[j] > 1).
	330	* Note that we always call this function with dis[i] > 1, so the
	331	* current line (i) is already a multimatch line.
	332	*/
	333	for (r = 1, rdis0 = 0, rpdis0 = 1; (i - r) >= s; r++) {
3443546f	334	if (!dis[i - r])
ca557aff	335	rdis0++;
3443546f	336	else if (dis[i - r] == 2)
ca557aff	337	rpdis0++;
3443546f LT	338	else
	339	break;
	340	}
ca557aff DL	341	/*
	342	* If the run before the line 'i' found only multimatch lines, we
	343	* return 0 and hence we don't make the current line (i) discarded.
	344	* We want to discard multimatch lines only when they appear in the
	345	* middle of runs with nomatch lines (dis[j] == 0).
	346	*/
	347	if (rdis0 == 0)
	348	return 0;
	349	for (r = 1, rdis1 = 0, rpdis1 = 1; (i + r) <= e; r++) {
3443546f	350	if (!dis[i + r])
ca557aff	351	rdis1++;
3443546f	352	else if (dis[i + r] == 2)
ca557aff	353	rpdis1++;
3443546f LT	354	else
	355	break;
	356	}
ca557aff DL	357	/*
	358	* If the run after the line 'i' found only multimatch lines, we
	359	* return 0 and hence we don't make the current line (i) discarded.
	360	*/
	361	if (rdis1 == 0)
	362	return 0;
	363	rdis1 += rdis0;
	364	rpdis1 += rpdis0;
	365
	366	return rpdis1 * XDL_KPDIS_RUN < (rpdis1 + rdis1);
3443546f LT	367	}
	368
	369
	370	/*
	371	* Try to reduce the problem complexity, discard records that have no
	372	* matches on the other file. Also, lines that have multiple matches
	373	* might be potentially discarded if they happear in a run of discardable.
	374	*/
	375	static int xdl_cleanup_records(xdfile_t xdf1, xdfile_t xdf2) {
ca557aff	376	long i, nm, rhi, nreff, mlim;
3443546f LT	377	unsigned long hav;
	378	xrecord_t **recs;
	379	xrecord_t *rec;
	380	char dis, dis1, *dis2;
	381
ca557aff	382	if (!(dis = (char *) xdl_malloc(xdf1->nrec + xdf2->nrec + 2))) {
3443546f LT	383
	384	return -1;
	385	}
ca557aff	386	memset(dis, 0, xdf1->nrec + xdf2->nrec + 2);
3443546f LT	387	dis1 = dis;
	388	dis2 = dis1 + xdf1->nrec + 1;
	389
ca557aff DL	390	if ((mlim = xdl_bogosqrt(xdf1->nrec)) > XDL_MAX_EQLIMIT)
ca557aff DL	391	mlim = XDL_MAX_EQLIMIT;
3443546f LT	392	for (i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart]; i <= xdf1->dend; i++, recs++) {
	393	hav = (*recs)->ha;
	394	rhi = (long) XDL_HASHLONG(hav, xdf2->hbits);
ca557aff DL	395	for (nm = 0, rec = xdf2->rhash[rhi]; rec; rec = rec->next)
ca557aff DL	396	if (rec->ha == hav && ++nm == mlim)
3443546f	397	break;
ca557aff	398	dis1[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
3443546f LT	399	}
3443546f LT	400
ca557aff DL	401	if ((mlim = xdl_bogosqrt(xdf2->nrec)) > XDL_MAX_EQLIMIT)
ca557aff DL	402	mlim = XDL_MAX_EQLIMIT;
3443546f LT	403	for (i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart]; i <= xdf2->dend; i++, recs++) {
	404	hav = (*recs)->ha;
	405	rhi = (long) XDL_HASHLONG(hav, xdf1->hbits);
ca557aff DL	406	for (nm = 0, rec = xdf1->rhash[rhi]; rec; rec = rec->next)
ca557aff DL	407	if (rec->ha == hav && ++nm == mlim)
3443546f	408	break;
ca557aff	409	dis2[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
3443546f LT	410	}
	411
	412	for (nreff = 0, i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart];
	413	i <= xdf1->dend; i++, recs++) {
	414	if (dis1[i] == 1 \|\|
	415	(dis1[i] == 2 && !xdl_clean_mmatch(dis1, i, xdf1->dstart, xdf1->dend))) {
	416	xdf1->rindex[nreff] = i;
	417	xdf1->ha[nreff] = (*recs)->ha;
	418	nreff++;
	419	} else
	420	xdf1->rchg[i] = 1;
	421	}
	422	xdf1->nreff = nreff;
	423
	424	for (nreff = 0, i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart];
	425	i <= xdf2->dend; i++, recs++) {
	426	if (dis2[i] == 1 \|\|
	427	(dis2[i] == 2 && !xdl_clean_mmatch(dis2, i, xdf2->dstart, xdf2->dend))) {
	428	xdf2->rindex[nreff] = i;
	429	xdf2->ha[nreff] = (*recs)->ha;
	430	nreff++;
	431	} else
	432	xdf2->rchg[i] = 1;
	433	}
	434	xdf2->nreff = nreff;
	435
	436	xdl_free(dis);
	437
	438	return 0;
	439	}
	440
	441
	442	/*
	443	* Early trim initial and terminal matching records.
	444	*/
	445	static int xdl_trim_ends(xdfile_t xdf1, xdfile_t xdf2) {
	446	long i, lim;
	447	xrecord_t recs1, recs2;
	448
	449	recs1 = xdf1->recs;
	450	recs2 = xdf2->recs;
	451	for (i = 0, lim = XDL_MIN(xdf1->nrec, xdf2->nrec); i < lim;
	452	i++, recs1++, recs2++)
	453	if ((recs1)->ha != (recs2)->ha)
	454	break;
	455
	456	xdf1->dstart = xdf2->dstart = i;
	457
	458	recs1 = xdf1->recs + xdf1->nrec - 1;
	459	recs2 = xdf2->recs + xdf2->nrec - 1;
	460	for (lim -= i, i = 0; i < lim; i++, recs1--, recs2--)
	461	if ((recs1)->ha != (recs2)->ha)
	462	break;
	463
	464	xdf1->dend = xdf1->nrec - i - 1;
	465	xdf2->dend = xdf2->nrec - i - 1;
	466
	467	return 0;
	468	}
	469
	470
	471	static int xdl_optimize_ctxs(xdfile_t xdf1, xdfile_t xdf2) {
	472
	473	if (xdl_trim_ends(xdf1, xdf2) < 0 \|\|
474	xdl_cleanup_records(xdf1, xdf2) < 0) {
475
476	return -1;
477	}
478
479	return 0;
480	}