Win32: fix detection of empty directories in is_dir_empty
[git/dscho.git] / xdiff / xprepare.c
blob63a22c630e521969b08c8ecb1ce9fa3e0f3ff513
1 /*
2 * LibXDiff by Davide Libenzi ( File Differential Library )
3 * Copyright (C) 2003 Davide Libenzi
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.
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.
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
19 * Davide Libenzi <davidel@xmailserver.org>
23 #include "xinclude.h"
26 #define XDL_KPDIS_RUN 4
27 #define XDL_MAX_EQLIMIT 1024
28 #define XDL_SIMSCAN_WINDOW 100
29 #define XDL_GUESS_NLINES1 256
30 #define XDL_GUESS_NLINES2 20
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 long len1, len2;
40 } xdlclass_t;
42 typedef struct s_xdlclassifier {
43 unsigned int hbits;
44 long hsize;
45 xdlclass_t **rchash;
46 chastore_t ncha;
47 xdlclass_t **rcrecs;
48 long alloc;
49 long count;
50 long flags;
51 } xdlclassifier_t;
56 static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags);
57 static void xdl_free_classifier(xdlclassifier_t *cf);
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,
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);
64 static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2);
65 static int xdl_trim_ends(xdfile_t *xdf1, xdfile_t *xdf2);
66 static int xdl_optimize_ctxs(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2);
71 static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags) {
72 cf->flags = flags;
74 cf->hbits = xdl_hashbits((unsigned int) size);
75 cf->hsize = 1 << cf->hbits;
77 if (xdl_cha_init(&cf->ncha, sizeof(xdlclass_t), size / 4 + 1) < 0) {
79 return -1;
81 if (!(cf->rchash = (xdlclass_t **) xdl_malloc(cf->hsize * sizeof(xdlclass_t *)))) {
83 xdl_cha_free(&cf->ncha);
84 return -1;
86 memset(cf->rchash, 0, cf->hsize * sizeof(xdlclass_t *));
88 cf->alloc = size;
89 if (!(cf->rcrecs = (xdlclass_t **) xdl_malloc(cf->alloc * sizeof(xdlclass_t *)))) {
91 xdl_free(cf->rchash);
92 xdl_cha_free(&cf->ncha);
93 return -1;
96 cf->count = 0;
98 return 0;
102 static void xdl_free_classifier(xdlclassifier_t *cf) {
104 xdl_free(cf->rcrecs);
105 xdl_free(cf->rchash);
106 xdl_cha_free(&cf->ncha);
110 static int xdl_classify_record(unsigned int pass, xdlclassifier_t *cf, xrecord_t **rhash,
111 unsigned int hbits, xrecord_t *rec) {
112 long hi;
113 char const *line;
114 xdlclass_t *rcrec;
115 xdlclass_t **rcrecs;
117 line = rec->ptr;
118 hi = (long) XDL_HASHLONG(rec->ha, cf->hbits);
119 for (rcrec = cf->rchash[hi]; rcrec; rcrec = rcrec->next)
120 if (rcrec->ha == rec->ha &&
121 xdl_recmatch(rcrec->line, rcrec->size,
122 rec->ptr, rec->size, cf->flags))
123 break;
125 if (!rcrec) {
126 if (!(rcrec = xdl_cha_alloc(&cf->ncha))) {
128 return -1;
130 rcrec->idx = cf->count++;
131 if (cf->count > cf->alloc) {
132 cf->alloc *= 2;
133 if (!(rcrecs = (xdlclass_t **) xdl_realloc(cf->rcrecs, cf->alloc * sizeof(xdlclass_t *)))) {
135 return -1;
137 cf->rcrecs = rcrecs;
139 cf->rcrecs[rcrec->idx] = rcrec;
140 rcrec->line = line;
141 rcrec->size = rec->size;
142 rcrec->ha = rec->ha;
143 rcrec->len1 = rcrec->len2 = 0;
144 rcrec->next = cf->rchash[hi];
145 cf->rchash[hi] = rcrec;
148 (pass == 1) ? rcrec->len1++ : rcrec->len2++;
150 rec->ha = (unsigned long) rcrec->idx;
152 hi = (long) XDL_HASHLONG(rec->ha, hbits);
153 rec->next = rhash[hi];
154 rhash[hi] = rec;
156 return 0;
160 static int xdl_prepare_ctx(unsigned int pass, mmfile_t *mf, long narec, xpparam_t const *xpp,
161 xdlclassifier_t *cf, xdfile_t *xdf) {
162 unsigned int hbits;
163 long nrec, hsize, bsize;
164 unsigned long hav;
165 char const *blk, *cur, *top, *prev;
166 xrecord_t *crec;
167 xrecord_t **recs, **rrecs;
168 xrecord_t **rhash;
169 unsigned long *ha;
170 char *rchg;
171 long *rindex;
173 ha = NULL;
174 rindex = NULL;
175 rchg = NULL;
176 rhash = NULL;
177 recs = NULL;
179 if (xdl_cha_init(&xdf->rcha, sizeof(xrecord_t), narec / 4 + 1) < 0)
180 goto abort;
181 if (!(recs = (xrecord_t **) xdl_malloc(narec * sizeof(xrecord_t *))))
182 goto abort;
184 if (XDF_DIFF_ALG(xpp->flags) == XDF_HISTOGRAM_DIFF)
185 hbits = hsize = 0;
186 else {
187 hbits = xdl_hashbits((unsigned int) narec);
188 hsize = 1 << hbits;
189 if (!(rhash = (xrecord_t **) xdl_malloc(hsize * sizeof(xrecord_t *))))
190 goto abort;
191 memset(rhash, 0, hsize * sizeof(xrecord_t *));
194 nrec = 0;
195 if ((cur = blk = xdl_mmfile_first(mf, &bsize)) != NULL) {
196 for (top = blk + bsize; cur < top; ) {
197 prev = cur;
198 hav = xdl_hash_record(&cur, top, xpp->flags);
199 if (nrec >= narec) {
200 narec *= 2;
201 if (!(rrecs = (xrecord_t **) xdl_realloc(recs, narec * sizeof(xrecord_t *))))
202 goto abort;
203 recs = rrecs;
205 if (!(crec = xdl_cha_alloc(&xdf->rcha)))
206 goto abort;
207 crec->ptr = prev;
208 crec->size = (long) (cur - prev);
209 crec->ha = hav;
210 recs[nrec++] = crec;
212 if ((XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF) &&
213 xdl_classify_record(pass, cf, rhash, hbits, crec) < 0)
214 goto abort;
218 if (!(rchg = (char *) xdl_malloc((nrec + 2) * sizeof(char))))
219 goto abort;
220 memset(rchg, 0, (nrec + 2) * sizeof(char));
222 if (!(rindex = (long *) xdl_malloc((nrec + 1) * sizeof(long))))
223 goto abort;
224 if (!(ha = (unsigned long *) xdl_malloc((nrec + 1) * sizeof(unsigned long))))
225 goto abort;
227 xdf->nrec = nrec;
228 xdf->recs = recs;
229 xdf->hbits = hbits;
230 xdf->rhash = rhash;
231 xdf->rchg = rchg + 1;
232 xdf->rindex = rindex;
233 xdf->nreff = 0;
234 xdf->ha = ha;
235 xdf->dstart = 0;
236 xdf->dend = nrec - 1;
238 return 0;
240 abort:
241 xdl_free(ha);
242 xdl_free(rindex);
243 xdl_free(rchg);
244 xdl_free(rhash);
245 xdl_free(recs);
246 xdl_cha_free(&xdf->rcha);
247 return -1;
251 static void xdl_free_ctx(xdfile_t *xdf) {
253 xdl_free(xdf->rhash);
254 xdl_free(xdf->rindex);
255 xdl_free(xdf->rchg - 1);
256 xdl_free(xdf->ha);
257 xdl_free(xdf->recs);
258 xdl_cha_free(&xdf->rcha);
262 int xdl_prepare_env(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
263 xdfenv_t *xe) {
264 long enl1, enl2, sample;
265 xdlclassifier_t cf;
267 memset(&cf, 0, sizeof(cf));
270 * For histogram diff, we can afford a smaller sample size and
271 * thus a poorer estimate of the number of lines, as the hash
272 * table (rhash) won't be filled up/grown. The number of lines
273 * (nrecs) will be updated correctly anyway by
274 * xdl_prepare_ctx().
276 sample = (XDF_DIFF_ALG(xpp->flags) == XDF_HISTOGRAM_DIFF
277 ? XDL_GUESS_NLINES2 : XDL_GUESS_NLINES1);
279 enl1 = xdl_guess_lines(mf1, sample) + 1;
280 enl2 = xdl_guess_lines(mf2, sample) + 1;
282 if (XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF &&
283 xdl_init_classifier(&cf, enl1 + enl2 + 1, xpp->flags) < 0)
284 return -1;
286 if (xdl_prepare_ctx(1, mf1, enl1, xpp, &cf, &xe->xdf1) < 0) {
288 xdl_free_classifier(&cf);
289 return -1;
291 if (xdl_prepare_ctx(2, mf2, enl2, xpp, &cf, &xe->xdf2) < 0) {
293 xdl_free_ctx(&xe->xdf1);
294 xdl_free_classifier(&cf);
295 return -1;
298 if ((XDF_DIFF_ALG(xpp->flags) != XDF_PATIENCE_DIFF) &&
299 (XDF_DIFF_ALG(xpp->flags) != XDF_HISTOGRAM_DIFF) &&
300 xdl_optimize_ctxs(&cf, &xe->xdf1, &xe->xdf2) < 0) {
302 xdl_free_ctx(&xe->xdf2);
303 xdl_free_ctx(&xe->xdf1);
304 return -1;
307 if (!(xpp->flags & XDF_HISTOGRAM_DIFF))
308 xdl_free_classifier(&cf);
310 return 0;
314 void xdl_free_env(xdfenv_t *xe) {
316 xdl_free_ctx(&xe->xdf2);
317 xdl_free_ctx(&xe->xdf1);
321 static int xdl_clean_mmatch(char const *dis, long i, long s, long e) {
322 long r, rdis0, rpdis0, rdis1, rpdis1;
325 * Limits the window the is examined during the similar-lines
326 * scan. The loops below stops when dis[i - r] == 1 (line that
327 * has no match), but there are corner cases where the loop
328 * proceed all the way to the extremities by causing huge
329 * performance penalties in case of big files.
331 if (i - s > XDL_SIMSCAN_WINDOW)
332 s = i - XDL_SIMSCAN_WINDOW;
333 if (e - i > XDL_SIMSCAN_WINDOW)
334 e = i + XDL_SIMSCAN_WINDOW;
337 * Scans the lines before 'i' to find a run of lines that either
338 * have no match (dis[j] == 0) or have multiple matches (dis[j] > 1).
339 * Note that we always call this function with dis[i] > 1, so the
340 * current line (i) is already a multimatch line.
342 for (r = 1, rdis0 = 0, rpdis0 = 1; (i - r) >= s; r++) {
343 if (!dis[i - r])
344 rdis0++;
345 else if (dis[i - r] == 2)
346 rpdis0++;
347 else
348 break;
351 * If the run before the line 'i' found only multimatch lines, we
352 * return 0 and hence we don't make the current line (i) discarded.
353 * We want to discard multimatch lines only when they appear in the
354 * middle of runs with nomatch lines (dis[j] == 0).
356 if (rdis0 == 0)
357 return 0;
358 for (r = 1, rdis1 = 0, rpdis1 = 1; (i + r) <= e; r++) {
359 if (!dis[i + r])
360 rdis1++;
361 else if (dis[i + r] == 2)
362 rpdis1++;
363 else
364 break;
367 * If the run after the line 'i' found only multimatch lines, we
368 * return 0 and hence we don't make the current line (i) discarded.
370 if (rdis1 == 0)
371 return 0;
372 rdis1 += rdis0;
373 rpdis1 += rpdis0;
375 return rpdis1 * XDL_KPDIS_RUN < (rpdis1 + rdis1);
380 * Try to reduce the problem complexity, discard records that have no
381 * matches on the other file. Also, lines that have multiple matches
382 * might be potentially discarded if they happear in a run of discardable.
384 static int xdl_cleanup_records(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2) {
385 long i, nm, nreff, mlim;
386 xrecord_t **recs;
387 xdlclass_t *rcrec;
388 char *dis, *dis1, *dis2;
390 if (!(dis = (char *) xdl_malloc(xdf1->nrec + xdf2->nrec + 2))) {
392 return -1;
394 memset(dis, 0, xdf1->nrec + xdf2->nrec + 2);
395 dis1 = dis;
396 dis2 = dis1 + xdf1->nrec + 1;
398 if ((mlim = xdl_bogosqrt(xdf1->nrec)) > XDL_MAX_EQLIMIT)
399 mlim = XDL_MAX_EQLIMIT;
400 for (i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart]; i <= xdf1->dend; i++, recs++) {
401 rcrec = cf->rcrecs[(*recs)->ha];
402 nm = rcrec ? rcrec->len2 : 0;
403 dis1[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
406 if ((mlim = xdl_bogosqrt(xdf2->nrec)) > XDL_MAX_EQLIMIT)
407 mlim = XDL_MAX_EQLIMIT;
408 for (i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart]; i <= xdf2->dend; i++, recs++) {
409 rcrec = cf->rcrecs[(*recs)->ha];
410 nm = rcrec ? rcrec->len1 : 0;
411 dis2[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
414 for (nreff = 0, i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart];
415 i <= xdf1->dend; i++, recs++) {
416 if (dis1[i] == 1 ||
417 (dis1[i] == 2 && !xdl_clean_mmatch(dis1, i, xdf1->dstart, xdf1->dend))) {
418 xdf1->rindex[nreff] = i;
419 xdf1->ha[nreff] = (*recs)->ha;
420 nreff++;
421 } else
422 xdf1->rchg[i] = 1;
424 xdf1->nreff = nreff;
426 for (nreff = 0, i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart];
427 i <= xdf2->dend; i++, recs++) {
428 if (dis2[i] == 1 ||
429 (dis2[i] == 2 && !xdl_clean_mmatch(dis2, i, xdf2->dstart, xdf2->dend))) {
430 xdf2->rindex[nreff] = i;
431 xdf2->ha[nreff] = (*recs)->ha;
432 nreff++;
433 } else
434 xdf2->rchg[i] = 1;
436 xdf2->nreff = nreff;
438 xdl_free(dis);
440 return 0;
445 * Early trim initial and terminal matching records.
447 static int xdl_trim_ends(xdfile_t *xdf1, xdfile_t *xdf2) {
448 long i, lim;
449 xrecord_t **recs1, **recs2;
451 recs1 = xdf1->recs;
452 recs2 = xdf2->recs;
453 for (i = 0, lim = XDL_MIN(xdf1->nrec, xdf2->nrec); i < lim;
454 i++, recs1++, recs2++)
455 if ((*recs1)->ha != (*recs2)->ha)
456 break;
458 xdf1->dstart = xdf2->dstart = i;
460 recs1 = xdf1->recs + xdf1->nrec - 1;
461 recs2 = xdf2->recs + xdf2->nrec - 1;
462 for (lim -= i, i = 0; i < lim; i++, recs1--, recs2--)
463 if ((*recs1)->ha != (*recs2)->ha)
464 break;
466 xdf1->dend = xdf1->nrec - i - 1;
467 xdf2->dend = xdf2->nrec - i - 1;
469 return 0;
473 static int xdl_optimize_ctxs(xdlclassifier_t *cf, xdfile_t *xdf1, xdfile_t *xdf2) {
475 if (xdl_trim_ends(xdf1, xdf2) < 0 ||
476 xdl_cleanup_records(cf, xdf1, xdf2) < 0) {
478 return -1;
481 return 0;