[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
#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;
} 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) {
	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->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 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 (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 (!(xpp->flags & XDF_HISTOGRAM_DIFF) &&
				xdl_classify_record(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 = 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 (!(xpp->flags & XDF_HISTOGRAM_DIFF) &&
		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;
	}

	if (!(xpp->flags & XDF_HISTOGRAM_DIFF))
		xdl_free_classifier(&cf);

	if (!(xpp->flags & XDF_PATIENCE_DIFF) &&
			!(xpp->flags & XDF_HISTOGRAM_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
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;
	39	} xdlclass_t;
	40
	41	typedef struct s_xdlclassifier {
	42	unsigned int hbits;
	43	long hsize;
	44	xdlclass_t **rchash;
	45	chastore_t ncha;
	46	long count;
0d21efa5	47	long flags;
3443546f LT	48	} xdlclassifier_t;
	49
	50
	51
	52
0d21efa5	53	static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags);
3443546f LT	54	static void xdl_free_classifier(xdlclassifier_t *cf);
	55	static int xdl_classify_record(xdlclassifier_t cf, xrecord_t *rhash, unsigned int hbits,
	56	xrecord_t *rec);
	57	static int xdl_prepare_ctx(mmfile_t mf, long narec, xpparam_t const xpp,
	58	xdlclassifier_t cf, xdfile_t xdf);
	59	static void xdl_free_ctx(xdfile_t *xdf);
	60	static int xdl_clean_mmatch(char const *dis, long i, long s, long e);
	61	static int xdl_cleanup_records(xdfile_t xdf1, xdfile_t xdf2);
	62	static int xdl_trim_ends(xdfile_t xdf1, xdfile_t xdf2);
	63	static int xdl_optimize_ctxs(xdfile_t xdf1, xdfile_t xdf2);
	64
	65
	66
	67
0d21efa5	68	static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags) {
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	}
452f4fa5	83	memset(cf->rchash, 0, cf->hsize * sizeof(xdlclass_t *));
3443546f LT	84
	85	cf->count = 0;
	86
	87	return 0;
	88	}
	89
	90
	91	static void xdl_free_classifier(xdlclassifier_t *cf) {
	92
	93	xdl_free(cf->rchash);
	94	xdl_cha_free(&cf->ncha);
	95	}
	96
	97
	98	static int xdl_classify_record(xdlclassifier_t cf, xrecord_t *rhash, unsigned int hbits,
	99	xrecord_t *rec) {
	100	long hi;
	101	char const *line;
	102	xdlclass_t *rcrec;
	103
	104	line = rec->ptr;
	105	hi = (long) XDL_HASHLONG(rec->ha, cf->hbits);
	106	for (rcrec = cf->rchash[hi]; rcrec; rcrec = rcrec->next)
0d21efa5 JS	107	if (rcrec->ha == rec->ha &&
	108	xdl_recmatch(rcrec->line, rcrec->size,
	109	rec->ptr, rec->size, cf->flags))
3443546f LT	110	break;
	111
	112	if (!rcrec) {
	113	if (!(rcrec = xdl_cha_alloc(&cf->ncha))) {
	114
	115	return -1;
	116	}
	117	rcrec->idx = cf->count++;
	118	rcrec->line = line;
	119	rcrec->size = rec->size;
	120	rcrec->ha = rec->ha;
	121	rcrec->next = cf->rchash[hi];
	122	cf->rchash[hi] = rcrec;
	123	}
	124
	125	rec->ha = (unsigned long) rcrec->idx;
	126
	127	hi = (long) XDL_HASHLONG(rec->ha, hbits);
	128	rec->next = rhash[hi];
	129	rhash[hi] = rec;
	130
	131	return 0;
	132	}
	133
	134
	135	static int xdl_prepare_ctx(mmfile_t mf, long narec, xpparam_t const xpp,
	136	xdlclassifier_t cf, xdfile_t xdf) {
	137	unsigned int hbits;
452f4fa5	138	long nrec, hsize, bsize;
3443546f LT	139	unsigned long hav;
	140	char const blk, cur, top, prev;
	141	xrecord_t *crec;
	142	xrecord_t recs, rrecs;
	143	xrecord_t **rhash;
	144	unsigned long *ha;
	145	char *rchg;
	146	long *rindex;
	147
159607a8 TRC	148	ha = NULL;
	149	rindex = NULL;
	150	rchg = NULL;
	151	rhash = NULL;
	152	recs = NULL;
3443546f	153
159607a8 TRC	154	if (xdl_cha_init(&xdf->rcha, sizeof(xrecord_t), narec / 4 + 1) < 0)
	155	goto abort;
	156	if (!(recs = (xrecord_t *) xdl_malloc(narec sizeof(xrecord_t *))))
	157	goto abort;
3443546f	158
9f37c275 TRC	159	if (xpp->flags & XDF_HISTOGRAM_DIFF)
	160	hbits = hsize = 0;
	161	else {
	162	hbits = xdl_hashbits((unsigned int) narec);
	163	hsize = 1 << hbits;
	164	if (!(rhash = (xrecord_t *) xdl_malloc(hsize sizeof(xrecord_t *))))
	165	goto abort;
	166	memset(rhash, 0, hsize * sizeof(xrecord_t *));
	167	}
3443546f LT	168
	169	nrec = 0;
	170	if ((cur = blk = xdl_mmfile_first(mf, &bsize)) != NULL) {
739864b1	171	for (top = blk + bsize; cur < top; ) {
3443546f	172	prev = cur;
0d21efa5	173	hav = xdl_hash_record(&cur, top, xpp->flags);
3443546f LT	174	if (nrec >= narec) {
3443546f LT	175	narec *= 2;
159607a8 TRC	176	if (!(rrecs = (xrecord_t *) xdl_realloc(recs, narec sizeof(xrecord_t *))))
159607a8 TRC	177	goto abort;
3443546f LT	178	recs = rrecs;
3443546f LT	179	}
159607a8 TRC	180	if (!(crec = xdl_cha_alloc(&xdf->rcha)))
159607a8 TRC	181	goto abort;
3443546f LT	182	crec->ptr = prev;
	183	crec->size = (long) (cur - prev);
	184	crec->ha = hav;
	185	recs[nrec++] = crec;
	186
9f37c275 TRC	187	if (!(xpp->flags & XDF_HISTOGRAM_DIFF) &&
9f37c275 TRC	188	xdl_classify_record(cf, rhash, hbits, crec) < 0)
159607a8	189	goto abort;
3443546f LT	190	}
	191	}
	192
159607a8 TRC	193	if (!(rchg = (char ) xdl_malloc((nrec + 2) sizeof(char))))
159607a8 TRC	194	goto abort;
3443546f LT	195	memset(rchg, 0, (nrec + 2) * sizeof(char));
3443546f LT	196
159607a8 TRC	197	if (!(rindex = (long ) xdl_malloc((nrec + 1) sizeof(long))))
	198	goto abort;
	199	if (!(ha = (unsigned long ) xdl_malloc((nrec + 1) sizeof(unsigned long))))
	200	goto abort;
3443546f LT	201
	202	xdf->nrec = nrec;
	203	xdf->recs = recs;
	204	xdf->hbits = hbits;
	205	xdf->rhash = rhash;
	206	xdf->rchg = rchg + 1;
	207	xdf->rindex = rindex;
	208	xdf->nreff = 0;
	209	xdf->ha = ha;
	210	xdf->dstart = 0;
	211	xdf->dend = nrec - 1;
	212
	213	return 0;
159607a8 TRC	214
	215	abort:
	216	xdl_free(ha);
	217	xdl_free(rindex);
	218	xdl_free(rchg);
	219	xdl_free(rhash);
	220	xdl_free(recs);
	221	xdl_cha_free(&xdf->rcha);
	222	return -1;
3443546f LT	223	}
	224
	225
	226	static void xdl_free_ctx(xdfile_t *xdf) {
	227
	228	xdl_free(xdf->rhash);
	229	xdl_free(xdf->rindex);
	230	xdl_free(xdf->rchg - 1);
	231	xdl_free(xdf->ha);
	232	xdl_free(xdf->recs);
	233	xdl_cha_free(&xdf->rcha);
	234	}
	235
	236
	237	int xdl_prepare_env(mmfile_t mf1, mmfile_t mf2, xpparam_t const *xpp,
	238	xdfenv_t *xe) {
86abba80	239	long enl1, enl2, sample;
3443546f LT	240	xdlclassifier_t cf;
3443546f LT	241
2738bc3f TRC	242	memset(&cf, 0, sizeof(cf));
2738bc3f TRC	243
86abba80 TRC	244	/*
	245	* For histogram diff, we can afford a smaller sample size and
	246	* thus a poorer estimate of the number of lines, as the hash
	247	* table (rhash) won't be filled up/grown. The number of lines
	248	* (nrecs) will be updated correctly anyway by
	249	* xdl_prepare_ctx().
	250	*/
	251	sample = xpp->flags & XDF_HISTOGRAM_DIFF ? XDL_GUESS_NLINES2 : XDL_GUESS_NLINES1;
	252
	253	enl1 = xdl_guess_lines(mf1, sample) + 1;
	254	enl2 = xdl_guess_lines(mf2, sample) + 1;
3443546f	255
9f37c275 TRC	256	if (!(xpp->flags & XDF_HISTOGRAM_DIFF) &&
9f37c275 TRC	257	xdl_init_classifier(&cf, enl1 + enl2 + 1, xpp->flags) < 0) {
3443546f LT	258
	259	return -1;
	260	}
	261
	262	if (xdl_prepare_ctx(mf1, enl1, xpp, &cf, &xe->xdf1) < 0) {
	263
	264	xdl_free_classifier(&cf);
	265	return -1;
	266	}
	267	if (xdl_prepare_ctx(mf2, enl2, xpp, &cf, &xe->xdf2) < 0) {
	268
	269	xdl_free_ctx(&xe->xdf1);
	270	xdl_free_classifier(&cf);
	271	return -1;
	272	}
	273
9f37c275 TRC	274	if (!(xpp->flags & XDF_HISTOGRAM_DIFF))
9f37c275 TRC	275	xdl_free_classifier(&cf);
3443546f	276
92b7de93	277	if (!(xpp->flags & XDF_PATIENCE_DIFF) &&
9f37c275	278	!(xpp->flags & XDF_HISTOGRAM_DIFF) &&
92b7de93	279	xdl_optimize_ctxs(&xe->xdf1, &xe->xdf2) < 0) {
3443546f LT	280
	281	xdl_free_ctx(&xe->xdf2);
	282	xdl_free_ctx(&xe->xdf1);
	283	return -1;
	284	}
	285
	286	return 0;
	287	}
	288
	289
	290	void xdl_free_env(xdfenv_t *xe) {
	291
	292	xdl_free_ctx(&xe->xdf2);
	293	xdl_free_ctx(&xe->xdf1);
	294	}
	295
	296
	297	static int xdl_clean_mmatch(char const *dis, long i, long s, long e) {
ca557aff DL	298	long r, rdis0, rpdis0, rdis1, rpdis1;
ca557aff DL	299
9b28d554 DL	300	/*
	301	* Limits the window the is examined during the similar-lines
	302	* scan. The loops below stops when dis[i - r] == 1 (line that
	303	* has no match), but there are corner cases where the loop
	304	* proceed all the way to the extremities by causing huge
	305	* performance penalties in case of big files.
	306	*/
	307	if (i - s > XDL_SIMSCAN_WINDOW)
	308	s = i - XDL_SIMSCAN_WINDOW;
	309	if (e - i > XDL_SIMSCAN_WINDOW)
	310	e = i + XDL_SIMSCAN_WINDOW;
	311
ca557aff DL	312	/*
	313	* Scans the lines before 'i' to find a run of lines that either
	314	* have no match (dis[j] == 0) or have multiple matches (dis[j] > 1).
	315	* Note that we always call this function with dis[i] > 1, so the
	316	* current line (i) is already a multimatch line.
	317	*/
	318	for (r = 1, rdis0 = 0, rpdis0 = 1; (i - r) >= s; r++) {
3443546f	319	if (!dis[i - r])
ca557aff	320	rdis0++;
3443546f	321	else if (dis[i - r] == 2)
ca557aff	322	rpdis0++;
3443546f LT	323	else
	324	break;
	325	}
ca557aff DL	326	/*
	327	* If the run before the line 'i' found only multimatch lines, we
	328	* return 0 and hence we don't make the current line (i) discarded.
	329	* We want to discard multimatch lines only when they appear in the
	330	* middle of runs with nomatch lines (dis[j] == 0).
	331	*/
	332	if (rdis0 == 0)
	333	return 0;
	334	for (r = 1, rdis1 = 0, rpdis1 = 1; (i + r) <= e; r++) {
3443546f	335	if (!dis[i + r])
ca557aff	336	rdis1++;
3443546f	337	else if (dis[i + r] == 2)
ca557aff	338	rpdis1++;
3443546f LT	339	else
	340	break;
	341	}
ca557aff DL	342	/*
	343	* If the run after the line 'i' found only multimatch lines, we
	344	* return 0 and hence we don't make the current line (i) discarded.
	345	*/
	346	if (rdis1 == 0)
	347	return 0;
	348	rdis1 += rdis0;
	349	rpdis1 += rpdis0;
	350
	351	return rpdis1 * XDL_KPDIS_RUN < (rpdis1 + rdis1);
3443546f LT	352	}
	353
	354
	355	/*
	356	* Try to reduce the problem complexity, discard records that have no
	357	* matches on the other file. Also, lines that have multiple matches
	358	* might be potentially discarded if they happear in a run of discardable.
	359	*/
	360	static int xdl_cleanup_records(xdfile_t xdf1, xdfile_t xdf2) {
ca557aff	361	long i, nm, rhi, nreff, mlim;
3443546f LT	362	unsigned long hav;
	363	xrecord_t **recs;
	364	xrecord_t *rec;
	365	char dis, dis1, *dis2;
	366
ca557aff	367	if (!(dis = (char *) xdl_malloc(xdf1->nrec + xdf2->nrec + 2))) {
3443546f LT	368
	369	return -1;
	370	}
ca557aff	371	memset(dis, 0, xdf1->nrec + xdf2->nrec + 2);
3443546f LT	372	dis1 = dis;
	373	dis2 = dis1 + xdf1->nrec + 1;
	374
ca557aff DL	375	if ((mlim = xdl_bogosqrt(xdf1->nrec)) > XDL_MAX_EQLIMIT)
ca557aff DL	376	mlim = XDL_MAX_EQLIMIT;
3443546f LT	377	for (i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart]; i <= xdf1->dend; i++, recs++) {
	378	hav = (*recs)->ha;
	379	rhi = (long) XDL_HASHLONG(hav, xdf2->hbits);
ca557aff DL	380	for (nm = 0, rec = xdf2->rhash[rhi]; rec; rec = rec->next)
ca557aff DL	381	if (rec->ha == hav && ++nm == mlim)
3443546f	382	break;
ca557aff	383	dis1[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
3443546f LT	384	}
3443546f LT	385
ca557aff DL	386	if ((mlim = xdl_bogosqrt(xdf2->nrec)) > XDL_MAX_EQLIMIT)
ca557aff DL	387	mlim = XDL_MAX_EQLIMIT;
3443546f LT	388	for (i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart]; i <= xdf2->dend; i++, recs++) {
	389	hav = (*recs)->ha;
	390	rhi = (long) XDL_HASHLONG(hav, xdf1->hbits);
ca557aff DL	391	for (nm = 0, rec = xdf1->rhash[rhi]; rec; rec = rec->next)
ca557aff DL	392	if (rec->ha == hav && ++nm == mlim)
3443546f	393	break;
ca557aff	394	dis2[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
3443546f LT	395	}
	396
	397	for (nreff = 0, i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart];
	398	i <= xdf1->dend; i++, recs++) {
	399	if (dis1[i] == 1 \|\|
	400	(dis1[i] == 2 && !xdl_clean_mmatch(dis1, i, xdf1->dstart, xdf1->dend))) {
	401	xdf1->rindex[nreff] = i;
	402	xdf1->ha[nreff] = (*recs)->ha;
	403	nreff++;
	404	} else
	405	xdf1->rchg[i] = 1;
	406	}
	407	xdf1->nreff = nreff;
	408
	409	for (nreff = 0, i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart];
	410	i <= xdf2->dend; i++, recs++) {
	411	if (dis2[i] == 1 \|\|
	412	(dis2[i] == 2 && !xdl_clean_mmatch(dis2, i, xdf2->dstart, xdf2->dend))) {
	413	xdf2->rindex[nreff] = i;
	414	xdf2->ha[nreff] = (*recs)->ha;
	415	nreff++;
	416	} else
	417	xdf2->rchg[i] = 1;
	418	}
	419	xdf2->nreff = nreff;
	420
	421	xdl_free(dis);
	422
	423	return 0;
	424	}
	425
	426
	427	/*
	428	* Early trim initial and terminal matching records.
	429	*/
	430	static int xdl_trim_ends(xdfile_t xdf1, xdfile_t xdf2) {
	431	long i, lim;
	432	xrecord_t recs1, recs2;
	433
	434	recs1 = xdf1->recs;
	435	recs2 = xdf2->recs;
	436	for (i = 0, lim = XDL_MIN(xdf1->nrec, xdf2->nrec); i < lim;
	437	i++, recs1++, recs2++)
	438	if ((recs1)->ha != (recs2)->ha)
	439	break;
	440
	441	xdf1->dstart = xdf2->dstart = i;
	442
	443	recs1 = xdf1->recs + xdf1->nrec - 1;
	444	recs2 = xdf2->recs + xdf2->nrec - 1;
	445	for (lim -= i, i = 0; i < lim; i++, recs1--, recs2--)
	446	if ((recs1)->ha != (recs2)->ha)
	447	break;
	448
	449	xdf1->dend = xdf1->nrec - i - 1;
	450	xdf2->dend = xdf2->nrec - i - 1;
	451
	452	return 0;
	453	}
	454
	455
	456	static int xdl_optimize_ctxs(xdfile_t xdf1, xdfile_t xdf2) {
	457
	458	if (xdl_trim_ends(xdf1, xdf2) < 0 \|\|
459	xdl_cleanup_records(xdf1, xdf2) < 0) {
460
461	return -1;
462	}
463
464	return 0;
465	}