diff options
Diffstat (limited to 'third_party/git/xdiff/xprepare.c')
| -rw-r--r-- | third_party/git/xdiff/xprepare.c | 483 |
1 files changed, 483 insertions, 0 deletions
diff --git a/third_party/git/xdiff/xprepare.c b/third_party/git/xdiff/xprepare.c new file mode 100644 index 000000000000..abeb8fb84e6d --- /dev/null +++ b/third_party/git/xdiff/xprepare.c @@ -0,0 +1,483 @@ +/* + * 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 = (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->alloc = size; + if (!(cf->rcrecs = (xdlclass_t **) xdl_malloc(cf->alloc * sizeof(xdlclass_t *)))) { + + 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 (!(recs = (xrecord_t **) xdl_malloc(narec * sizeof(xrecord_t *)))) + goto abort; + + if (XDF_DIFF_ALG(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 ((XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF) && + xdl_classify_record(pass, 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 = (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 (XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF && + 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; + } + + if (XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF) + 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 = (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++) { + 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; +} |