[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 (!(cf->rchash = xdl_calloc(cf->hsize, sizeof(*cf->rchash)))) {

		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;
	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 (!XDL_ALLOC_ARRAY(recs, narec))
		goto abort;

	hbits = xdl_hashbits((unsigned int) narec);
	hsize = 1 << hbits;
	if (!(rhash = xdl_calloc(hsize, sizeof(*rhash))))
		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 (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 (xdl_classify_record(pass, cf, rhash, hbits, crec) < 0)
				goto abort;
		}
	}

	if (!(rchg = xdl_calloc((nrec + 2), sizeof(*rchg))))
		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 (!(dis = xdl_calloc(xdf1->nrec + xdf2->nrec + 2, sizeof(*dis)))) {

		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	}
18aae7e2	81	if (!(cf->rchash = xdl_calloc(cf->hsize, sizeof(*cf->rchash)))) {
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;
27af01d5	114	xdlclass_t **rcrecs;
3443546f LT	115
	116	line = rec->ptr;
	117	hi = (long) XDL_HASHLONG(rec->ha, cf->hbits);
	118	for (rcrec = cf->rchash[hi]; rcrec; rcrec = rcrec->next)
0d21efa5 JS	119	if (rcrec->ha == rec->ha &&
	120	xdl_recmatch(rcrec->line, rcrec->size,
	121	rec->ptr, rec->size, cf->flags))
3443546f LT	122	break;
	123
	124	if (!rcrec) {
	125	if (!(rcrec = xdl_cha_alloc(&cf->ncha))) {
	126
	127	return -1;
	128	}
	129	rcrec->idx = cf->count++;
27af01d5 TRC	130	if (cf->count > cf->alloc) {
	131	cf->alloc *= 2;
	132	if (!(rcrecs = (xdlclass_t *) xdl_realloc(cf->rcrecs, cf->alloc sizeof(xdlclass_t *)))) {
	133
	134	return -1;
	135	}
	136	cf->rcrecs = rcrecs;
	137	}
	138	cf->rcrecs[rcrec->idx] = rcrec;
3443546f LT	139	rcrec->line = line;
	140	rcrec->size = rec->size;
	141	rcrec->ha = rec->ha;
27af01d5	142	rcrec->len1 = rcrec->len2 = 0;
3443546f LT	143	rcrec->next = cf->rchash[hi];
	144	cf->rchash[hi] = rcrec;
	145	}
	146
27af01d5 TRC	147	(pass == 1) ? rcrec->len1++ : rcrec->len2++;
27af01d5 TRC	148
3443546f LT	149	rec->ha = (unsigned long) rcrec->idx;
	150
	151	hi = (long) XDL_HASHLONG(rec->ha, hbits);
	152	rec->next = rhash[hi];
	153	rhash[hi] = rec;
	154
	155	return 0;
	156	}
	157
	158
27af01d5	159	static int xdl_prepare_ctx(unsigned int pass, mmfile_t mf, long narec, xpparam_t const xpp,
3443546f LT	160	xdlclassifier_t cf, xdfile_t xdf) {
3443546f LT	161	unsigned int hbits;
452f4fa5	162	long nrec, hsize, bsize;
3443546f LT	163	unsigned long hav;
	164	char const blk, cur, top, prev;
	165	xrecord_t *crec;
	166	xrecord_t recs, rrecs;
	167	xrecord_t **rhash;
	168	unsigned long *ha;
	169	char *rchg;
	170	long *rindex;
	171
159607a8 TRC	172	ha = NULL;
	173	rindex = NULL;
	174	rchg = NULL;
	175	rhash = NULL;
	176	recs = NULL;
3443546f	177
159607a8 TRC	178	if (xdl_cha_init(&xdf->rcha, sizeof(xrecord_t), narec / 4 + 1) < 0)
159607a8 TRC	179	goto abort;
abf04bda	180	if (!XDL_ALLOC_ARRAY(recs, narec))
159607a8	181	goto abort;
3443546f	182
663c5ad0 PW	183	hbits = xdl_hashbits((unsigned int) narec);
663c5ad0 PW	184	hsize = 1 << hbits;
18aae7e2	185	if (!(rhash = xdl_calloc(hsize, sizeof(*rhash))))
663c5ad0	186	goto abort;
3443546f LT	187
3443546f LT	188	nrec = 0;
afe8a907	189	if ((cur = blk = xdl_mmfile_first(mf, &bsize))) {
739864b1	190	for (top = blk + bsize; cur < top; ) {
3443546f	191	prev = cur;
0d21efa5	192	hav = xdl_hash_record(&cur, top, xpp->flags);
3443546f LT	193	if (nrec >= narec) {
3443546f LT	194	narec *= 2;
159607a8 TRC	195	if (!(rrecs = (xrecord_t *) xdl_realloc(recs, narec sizeof(xrecord_t *))))
159607a8 TRC	196	goto abort;
3443546f LT	197	recs = rrecs;
3443546f LT	198	}
159607a8 TRC	199	if (!(crec = xdl_cha_alloc(&xdf->rcha)))
159607a8 TRC	200	goto abort;
3443546f LT	201	crec->ptr = prev;
	202	crec->size = (long) (cur - prev);
	203	crec->ha = hav;
	204	recs[nrec++] = crec;
663c5ad0	205	if (xdl_classify_record(pass, cf, rhash, hbits, crec) < 0)
159607a8	206	goto abort;
3443546f LT	207	}
	208	}
	209
18aae7e2	210	if (!(rchg = xdl_calloc((nrec + 2), sizeof(*rchg))))
159607a8	211	goto abort;
3443546f	212
b82dd3f7 PW	213	if ((XDF_DIFF_ALG(xpp->flags) != XDF_PATIENCE_DIFF) &&
b82dd3f7 PW	214	(XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF)) {
abf04bda	215	if (!XDL_ALLOC_ARRAY(rindex, nrec + 1))
b82dd3f7	216	goto abort;
abf04bda	217	if (!XDL_ALLOC_ARRAY(ha, nrec + 1))
b82dd3f7 PW	218	goto abort;
b82dd3f7 PW	219	}
3443546f LT	220
	221	xdf->nrec = nrec;
	222	xdf->recs = recs;
	223	xdf->hbits = hbits;
	224	xdf->rhash = rhash;
	225	xdf->rchg = rchg + 1;
	226	xdf->rindex = rindex;
	227	xdf->nreff = 0;
	228	xdf->ha = ha;
	229	xdf->dstart = 0;
	230	xdf->dend = nrec - 1;
	231
	232	return 0;
159607a8 TRC	233
	234	abort:
	235	xdl_free(ha);
	236	xdl_free(rindex);
	237	xdl_free(rchg);
	238	xdl_free(rhash);
	239	xdl_free(recs);
	240	xdl_cha_free(&xdf->rcha);
	241	return -1;
3443546f LT	242	}
	243
	244
	245	static void xdl_free_ctx(xdfile_t *xdf) {
	246
	247	xdl_free(xdf->rhash);
	248	xdl_free(xdf->rindex);
	249	xdl_free(xdf->rchg - 1);
	250	xdl_free(xdf->ha);
	251	xdl_free(xdf->recs);
	252	xdl_cha_free(&xdf->rcha);
	253	}
	254
	255
	256	int xdl_prepare_env(mmfile_t mf1, mmfile_t mf2, xpparam_t const *xpp,
	257	xdfenv_t *xe) {
86abba80	258	long enl1, enl2, sample;
3443546f LT	259	xdlclassifier_t cf;
3443546f LT	260
2738bc3f TRC	261	memset(&cf, 0, sizeof(cf));
2738bc3f TRC	262
86abba80 TRC	263	/*
	264	* For histogram diff, we can afford a smaller sample size and
	265	* thus a poorer estimate of the number of lines, as the hash
	266	* table (rhash) won't be filled up/grown. The number of lines
	267	* (nrecs) will be updated correctly anyway by
	268	* xdl_prepare_ctx().
	269	*/
307ab20b JH	270	sample = (XDF_DIFF_ALG(xpp->flags) == XDF_HISTOGRAM_DIFF
307ab20b JH	271	? XDL_GUESS_NLINES2 : XDL_GUESS_NLINES1);
86abba80 TRC	272
	273	enl1 = xdl_guess_lines(mf1, sample) + 1;
	274	enl2 = xdl_guess_lines(mf2, sample) + 1;
3443546f	275
663c5ad0	276	if (xdl_init_classifier(&cf, enl1 + enl2 + 1, xpp->flags) < 0)
3443546f	277	return -1;
3443546f	278
27af01d5	279	if (xdl_prepare_ctx(1, mf1, enl1, xpp, &cf, &xe->xdf1) < 0) {
3443546f LT	280
	281	xdl_free_classifier(&cf);
	282	return -1;
	283	}
27af01d5	284	if (xdl_prepare_ctx(2, mf2, enl2, xpp, &cf, &xe->xdf2) < 0) {
3443546f LT	285
	286	xdl_free_ctx(&xe->xdf1);
	287	xdl_free_classifier(&cf);
	288	return -1;
	289	}
	290
307ab20b JH	291	if ((XDF_DIFF_ALG(xpp->flags) != XDF_PATIENCE_DIFF) &&
	292	(XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF) &&
	293	xdl_optimize_ctxs(&cf, &xe->xdf1, &xe->xdf2) < 0) {
3443546f LT	294
	295	xdl_free_ctx(&xe->xdf2);
	296	xdl_free_ctx(&xe->xdf1);
87f16258	297	xdl_free_classifier(&cf);
3443546f LT	298	return -1;
	299	}
	300
663c5ad0	301	xdl_free_classifier(&cf);
27af01d5	302
3443546f LT	303	return 0;
	304	}
	305
	306
	307	void xdl_free_env(xdfenv_t *xe) {
	308
	309	xdl_free_ctx(&xe->xdf2);
	310	xdl_free_ctx(&xe->xdf1);
	311	}
	312
	313
	314	static int xdl_clean_mmatch(char const *dis, long i, long s, long e) {
ca557aff DL	315	long r, rdis0, rpdis0, rdis1, rpdis1;
ca557aff DL	316
9b28d554 DL	317	/*
	318	* Limits the window the is examined during the similar-lines
	319	* scan. The loops below stops when dis[i - r] == 1 (line that
	320	* has no match), but there are corner cases where the loop
	321	* proceed all the way to the extremities by causing huge
	322	* performance penalties in case of big files.
	323	*/
	324	if (i - s > XDL_SIMSCAN_WINDOW)
	325	s = i - XDL_SIMSCAN_WINDOW;
	326	if (e - i > XDL_SIMSCAN_WINDOW)
	327	e = i + XDL_SIMSCAN_WINDOW;
	328
ca557aff DL	329	/*
	330	* Scans the lines before 'i' to find a run of lines that either
	331	* have no match (dis[j] == 0) or have multiple matches (dis[j] > 1).
	332	* Note that we always call this function with dis[i] > 1, so the
	333	* current line (i) is already a multimatch line.
	334	*/
	335	for (r = 1, rdis0 = 0, rpdis0 = 1; (i - r) >= s; r++) {
3443546f	336	if (!dis[i - r])
ca557aff	337	rdis0++;
3443546f	338	else if (dis[i - r] == 2)
ca557aff	339	rpdis0++;
3443546f LT	340	else
	341	break;
	342	}
ca557aff DL	343	/*
	344	* If the run before the line 'i' found only multimatch lines, we
	345	* return 0 and hence we don't make the current line (i) discarded.
	346	* We want to discard multimatch lines only when they appear in the
	347	* middle of runs with nomatch lines (dis[j] == 0).
	348	*/
	349	if (rdis0 == 0)
	350	return 0;
	351	for (r = 1, rdis1 = 0, rpdis1 = 1; (i + r) <= e; r++) {
3443546f	352	if (!dis[i + r])
ca557aff	353	rdis1++;
3443546f	354	else if (dis[i + r] == 2)
ca557aff	355	rpdis1++;
3443546f LT	356	else
	357	break;
	358	}
ca557aff DL	359	/*
	360	* If the run after the line 'i' found only multimatch lines, we
	361	* return 0 and hence we don't make the current line (i) discarded.
	362	*/
	363	if (rdis1 == 0)
	364	return 0;
	365	rdis1 += rdis0;
	366	rpdis1 += rpdis0;
	367
	368	return rpdis1 * XDL_KPDIS_RUN < (rpdis1 + rdis1);
3443546f LT	369	}
	370
	371
	372	/*
	373	* Try to reduce the problem complexity, discard records that have no
	374	* matches on the other file. Also, lines that have multiple matches
	375	* might be potentially discarded if they happear in a run of discardable.
	376	*/
27af01d5	377	static int xdl_cleanup_records(xdlclassifier_t cf, xdfile_t xdf1, xdfile_t *xdf2) {
c5aa9068	378	long i, nm, nreff, mlim;
3443546f	379	xrecord_t **recs;
27af01d5	380	xdlclass_t *rcrec;
3443546f LT	381	char dis, dis1, *dis2;
3443546f LT	382
18aae7e2	383	if (!(dis = xdl_calloc(xdf1->nrec + xdf2->nrec + 2, sizeof(*dis)))) {
3443546f LT	384
	385	return -1;
	386	}
3443546f LT	387	dis1 = dis;
	388	dis2 = dis1 + xdf1->nrec + 1;
	389
c5aa9068 RS	390	if ((mlim = xdl_bogosqrt(xdf1->nrec)) > XDL_MAX_EQLIMIT)
c5aa9068 RS	391	mlim = XDL_MAX_EQLIMIT;
3443546f	392	for (i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart]; i <= xdf1->dend; i++, recs++) {
27af01d5 TRC	393	rcrec = cf->rcrecs[(*recs)->ha];
27af01d5 TRC	394	nm = rcrec ? rcrec->len2 : 0;
c5aa9068	395	dis1[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
3443546f LT	396	}
3443546f LT	397
c5aa9068 RS	398	if ((mlim = xdl_bogosqrt(xdf2->nrec)) > XDL_MAX_EQLIMIT)
c5aa9068 RS	399	mlim = XDL_MAX_EQLIMIT;
3443546f	400	for (i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart]; i <= xdf2->dend; i++, recs++) {
27af01d5 TRC	401	rcrec = cf->rcrecs[(*recs)->ha];
27af01d5 TRC	402	nm = rcrec ? rcrec->len1 : 0;
c5aa9068	403	dis2[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
3443546f LT	404	}
	405
	406	for (nreff = 0, i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart];
	407	i <= xdf1->dend; i++, recs++) {
	408	if (dis1[i] == 1 \|\|
	409	(dis1[i] == 2 && !xdl_clean_mmatch(dis1, i, xdf1->dstart, xdf1->dend))) {
	410	xdf1->rindex[nreff] = i;
	411	xdf1->ha[nreff] = (*recs)->ha;
	412	nreff++;
	413	} else
	414	xdf1->rchg[i] = 1;
	415	}
	416	xdf1->nreff = nreff;
	417
	418	for (nreff = 0, i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart];
	419	i <= xdf2->dend; i++, recs++) {
	420	if (dis2[i] == 1 \|\|
	421	(dis2[i] == 2 && !xdl_clean_mmatch(dis2, i, xdf2->dstart, xdf2->dend))) {
	422	xdf2->rindex[nreff] = i;
	423	xdf2->ha[nreff] = (*recs)->ha;
	424	nreff++;
	425	} else
	426	xdf2->rchg[i] = 1;
	427	}
	428	xdf2->nreff = nreff;
	429
	430	xdl_free(dis);
	431
	432	return 0;
	433	}
	434
	435
	436	/*
	437	* Early trim initial and terminal matching records.
	438	*/
	439	static int xdl_trim_ends(xdfile_t xdf1, xdfile_t xdf2) {
	440	long i, lim;
	441	xrecord_t recs1, recs2;
	442
	443	recs1 = xdf1->recs;
	444	recs2 = xdf2->recs;
	445	for (i = 0, lim = XDL_MIN(xdf1->nrec, xdf2->nrec); i < lim;
	446	i++, recs1++, recs2++)
	447	if ((recs1)->ha != (recs2)->ha)
	448	break;
	449
	450	xdf1->dstart = xdf2->dstart = i;
	451
	452	recs1 = xdf1->recs + xdf1->nrec - 1;
	453	recs2 = xdf2->recs + xdf2->nrec - 1;
	454	for (lim -= i, i = 0; i < lim; i++, recs1--, recs2--)
	455	if ((recs1)->ha != (recs2)->ha)
	456	break;
	457
	458	xdf1->dend = xdf1->nrec - i - 1;
	459	xdf2->dend = xdf2->nrec - i - 1;
	460
	461	return 0;
	462	}
	463
	464
27af01d5	465	static int xdl_optimize_ctxs(xdlclassifier_t cf, xdfile_t xdf1, xdfile_t *xdf2) {
3443546f LT	466
3443546f LT	467	if (xdl_trim_ends(xdf1, xdf2) < 0 \|\|
27af01d5	468	xdl_cleanup_records(cf, xdf1, xdf2) < 0) {
3443546f LT	469
	470	return -1;
	471	}
	472
	473	return 0;
	474	}