xdiff/xprepare: improve O(n*m) performance in xdl_cleanup_records()
In xdl_cleanup_records(), we see O(n*m) performance, where n is the number of records from xdf->dstart to xdf->dend, and m is the size of a bucket in xdf->rhash (<= by mlim). Here, we improve this to O(n) by pre-computing nm (in rcrec->len(1|2)) in xdl_classify_record(). Reported-by: Marat Radchenko <marat@slonopotamus.org> Signed-off-by: Tay Ray Chuan <rctay89@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Tay Ray Chuan committed
Aug 17, 2011 at 09:53 UTC
27af01d552331eacf1ed2671b2b4b6ad4c268106
1 file changed
+50
-36
xdiff/xprepare.c
+50
-36
@@ -34,6 +34,7 @@ typedef struct s_xdlclass {
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char const *line;
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long size;
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long idx;
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+ long len1, len2;
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} xdlclass_t;
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typedef struct s_xdlclassifier {
@@ -41,6 +42,8 @@ typedef struct s_xdlclassifier {
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long hsize;
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xdlclass_t **rchash;
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chastore_t ncha;
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+ xdlclass_t **rcrecs;
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+ long alloc;
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long count;
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long flags;
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} xdlclassifier_t;
@@ -50,15 +53,15 @@ typedef struct s_xdlclassifier {
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static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags);
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static void xdl_free_classifier(xdlclassifier_t *cf);
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-static int xdl_classify_record(xdlclassifier_t *cf, xrecord_t **rhash, unsigned int hbits,
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- xrecord_t *rec);
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-static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
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+static int xdl_classify_record(unsigned int pass, xdlclassifier_t *cf, xrecord_t **rhash,
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+ unsigned int hbits, xrecord_t *rec);
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+static int xdl_prepare_ctx(unsigned int pass, mmfile_t *mf, long narec, xpparam_t const *xpp,
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xdlclassifier_t *cf, xdfile_t *xdf);
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static void xdl_free_ctx(xdfile_t *xdf);
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static int xdl_clean_mmatch(char const *dis, long i, long s, long e);
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-static int xdl_cleanup_records(xdfile_t *xdf1, xdfile_t *xdf2);
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+static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2);
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static int xdl_trim_ends(xdfile_t *xdf1, xdfile_t *xdf2);
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-static int xdl_optimize_ctxs(xdfile_t *xdf1, xdfile_t *xdf2);
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+static int xdl_optimize_ctxs(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2);
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@@ -83,6 +86,14 @@ static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags) {
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for (i = 0; i < cf->hsize; i++)
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cf->rchash[i] = NULL;
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+ cf->alloc = size;
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+ if (!(cf->rcrecs = (xdlclass_t **) xdl_malloc(cf->alloc * sizeof(xdlclass_t *)))) {
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+
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+ xdl_free(cf->rchash);
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+ xdl_cha_free(&cf->ncha);
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+ return -1;
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+ }
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+
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cf->count = 0;
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return 0;
@@ -91,16 +102,18 @@ static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags) {
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static void xdl_free_classifier(xdlclassifier_t *cf) {
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+ xdl_free(cf->rcrecs);
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xdl_free(cf->rchash);
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xdl_cha_free(&cf->ncha);
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}
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-static int xdl_classify_record(xdlclassifier_t *cf, xrecord_t **rhash, unsigned int hbits,
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- xrecord_t *rec) {
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+static int xdl_classify_record(unsigned int pass, xdlclassifier_t *cf, xrecord_t **rhash,
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+ unsigned int hbits, xrecord_t *rec) {
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long hi;
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char const *line;
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xdlclass_t *rcrec;
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+ xdlclass_t **rcrecs;
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line = rec->ptr;
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hi = (long) XDL_HASHLONG(rec->ha, cf->hbits);
@@ -116,13 +129,25 @@ static int xdl_classify_record(xdlclassifier_t *cf, xrecord_t **rhash, unsigned
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return -1;
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}
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rcrec->idx = cf->count++;
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+ if (cf->count > cf->alloc) {
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+ cf->alloc *= 2;
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+ if (!(rcrecs = (xdlclass_t **) xdl_realloc(cf->rcrecs, cf->alloc * sizeof(xdlclass_t *)))) {
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+
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+ return -1;
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+ }
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+ cf->rcrecs = rcrecs;
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+ }
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+ cf->rcrecs[rcrec->idx] = rcrec;
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rcrec->line = line;
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rcrec->size = rec->size;
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rcrec->ha = rec->ha;
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+ rcrec->len1 = rcrec->len2 = 0;
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rcrec->next = cf->rchash[hi];
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cf->rchash[hi] = rcrec;
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}
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+ (pass == 1) ? rcrec->len1++ : rcrec->len2++;
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+
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rec->ha = (unsigned long) rcrec->idx;
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hi = (long) XDL_HASHLONG(rec->ha, hbits);
@@ -133,7 +158,7 @@ static int xdl_classify_record(xdlclassifier_t *cf, xrecord_t **rhash, unsigned
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}
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-static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
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+static int xdl_prepare_ctx(unsigned int pass, mmfile_t *mf, long narec, xpparam_t const *xpp,
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xdlclassifier_t *cf, xdfile_t *xdf) {
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unsigned int hbits;
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long i, nrec, hsize, bsize;
@@ -200,7 +225,7 @@ static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
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crec->ha = hav;
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recs[nrec++] = crec;
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- if (xdl_classify_record(cf, rhash, hbits, crec) < 0) {
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+ if (xdl_classify_record(pass, cf, rhash, hbits, crec) < 0) {
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xdl_free(rhash);
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xdl_free(recs);
@@ -276,28 +301,28 @@ int xdl_prepare_env(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
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return -1;
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}
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- if (xdl_prepare_ctx(mf1, enl1, xpp, &cf, &xe->xdf1) < 0) {
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+ if (xdl_prepare_ctx(1, mf1, enl1, xpp, &cf, &xe->xdf1) < 0) {
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xdl_free_classifier(&cf);
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return -1;
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}
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- if (xdl_prepare_ctx(mf2, enl2, xpp, &cf, &xe->xdf2) < 0) {
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+ if (xdl_prepare_ctx(2, mf2, enl2, xpp, &cf, &xe->xdf2) < 0) {
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xdl_free_ctx(&xe->xdf1);
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xdl_free_classifier(&cf);
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return -1;
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}
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- xdl_free_classifier(&cf);
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-
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if (!(xpp->flags & XDF_PATIENCE_DIFF) &&
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- xdl_optimize_ctxs(&xe->xdf1, &xe->xdf2) < 0) {
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+ xdl_optimize_ctxs(&cf, &xe->xdf1, &xe->xdf2) < 0) {
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xdl_free_ctx(&xe->xdf2);
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xdl_free_ctx(&xe->xdf1);
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return -1;
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}
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+ xdl_free_classifier(&cf);
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+
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return 0;
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}
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@@ -372,11 +397,10 @@ static int xdl_clean_mmatch(char const *dis, long i, long s, long e) {
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* matches on the other file. Also, lines that have multiple matches
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* might be potentially discarded if they happear in a run of discardable.
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*/
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-static int xdl_cleanup_records(xdfile_t *xdf1, xdfile_t *xdf2) {
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- long i, nm, rhi, nreff, mlim;
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- unsigned long hav;
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+static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2) {
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+ long i, nm, nreff;
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xrecord_t **recs;
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- xrecord_t *rec;
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+ xdlclass_t *rcrec;
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char *dis, *dis1, *dis2;
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if (!(dis = (char *) xdl_malloc(xdf1->nrec + xdf2->nrec + 2))) {
@@ -387,26 +411,16 @@ static int xdl_cleanup_records(xdfile_t *xdf1, xdfile_t *xdf2) {
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dis1 = dis;
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dis2 = dis1 + xdf1->nrec + 1;
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- if ((mlim = xdl_bogosqrt(xdf1->nrec)) > XDL_MAX_EQLIMIT)
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- mlim = XDL_MAX_EQLIMIT;
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for (i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart]; i <= xdf1->dend; i++, recs++) {
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- hav = (*recs)->ha;
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- rhi = (long) XDL_HASHLONG(hav, xdf2->hbits);
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- for (nm = 0, rec = xdf2->rhash[rhi]; rec; rec = rec->next)
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- if (rec->ha == hav && ++nm == mlim)
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- break;
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- dis1[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
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+ rcrec = cf->rcrecs[(*recs)->ha];
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+ nm = rcrec ? rcrec->len2 : 0;
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+ dis1[i] = (nm == 0) ? 0: 1;
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}
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- if ((mlim = xdl_bogosqrt(xdf2->nrec)) > XDL_MAX_EQLIMIT)
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- mlim = XDL_MAX_EQLIMIT;
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for (i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart]; i <= xdf2->dend; i++, recs++) {
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- hav = (*recs)->ha;
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- rhi = (long) XDL_HASHLONG(hav, xdf1->hbits);
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- for (nm = 0, rec = xdf1->rhash[rhi]; rec; rec = rec->next)
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- if (rec->ha == hav && ++nm == mlim)
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- break;
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- dis2[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
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+ rcrec = cf->rcrecs[(*recs)->ha];
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+ nm = rcrec ? rcrec->len1 : 0;
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+ dis2[i] = (nm == 0) ? 0: 1;
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}
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for (nreff = 0, i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart];
@@ -468,10 +482,10 @@ static int xdl_trim_ends(xdfile_t *xdf1, xdfile_t *xdf2) {
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}
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-static int xdl_optimize_ctxs(xdfile_t *xdf1, xdfile_t *xdf2) {
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+static int xdl_optimize_ctxs(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2) {
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if (xdl_trim_ends(xdf1, xdf2) < 0 ||
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- xdl_cleanup_records(xdf1, xdf2) < 0) {
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+ xdl_cleanup_records(cf, xdf1, xdf2) < 0) {
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return -1;
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}