xdiff/xprepare: use memset()
[git/git.git] / xdiff / xprepare.c
CommitLineData
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
3443546f
LT
29
30
31typedef struct s_xdlclass {
32 struct s_xdlclass *next;
33 unsigned long ha;
34 char const *line;
35 long size;
36 long idx;
37} xdlclass_t;
38
39typedef struct s_xdlclassifier {
40 unsigned int hbits;
41 long hsize;
42 xdlclass_t **rchash;
43 chastore_t ncha;
44 long count;
0d21efa5 45 long flags;
3443546f
LT
46} xdlclassifier_t;
47
48
49
50
0d21efa5 51static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags);
3443546f
LT
52static void xdl_free_classifier(xdlclassifier_t *cf);
53static int xdl_classify_record(xdlclassifier_t *cf, xrecord_t **rhash, unsigned int hbits,
54 xrecord_t *rec);
55static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
56 xdlclassifier_t *cf, xdfile_t *xdf);
57static void xdl_free_ctx(xdfile_t *xdf);
58static int xdl_clean_mmatch(char const *dis, long i, long s, long e);
59static int xdl_cleanup_records(xdfile_t *xdf1, xdfile_t *xdf2);
60static int xdl_trim_ends(xdfile_t *xdf1, xdfile_t *xdf2);
61static int xdl_optimize_ctxs(xdfile_t *xdf1, xdfile_t *xdf2);
62
63
64
65
0d21efa5 66static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags) {
0d21efa5
JS
67 cf->flags = flags;
68
3443546f
LT
69 cf->hbits = xdl_hashbits((unsigned int) size);
70 cf->hsize = 1 << cf->hbits;
71
72 if (xdl_cha_init(&cf->ncha, sizeof(xdlclass_t), size / 4 + 1) < 0) {
73
74 return -1;
75 }
76 if (!(cf->rchash = (xdlclass_t **) xdl_malloc(cf->hsize * sizeof(xdlclass_t *)))) {
77
78 xdl_cha_free(&cf->ncha);
79 return -1;
80 }
452f4fa5 81 memset(cf->rchash, 0, cf->hsize * sizeof(xdlclass_t *));
3443546f
LT
82
83 cf->count = 0;
84
85 return 0;
86}
87
88
89static void xdl_free_classifier(xdlclassifier_t *cf) {
90
91 xdl_free(cf->rchash);
92 xdl_cha_free(&cf->ncha);
93}
94
95
96static int xdl_classify_record(xdlclassifier_t *cf, xrecord_t **rhash, unsigned int hbits,
97 xrecord_t *rec) {
98 long hi;
99 char const *line;
100 xdlclass_t *rcrec;
101
102 line = rec->ptr;
103 hi = (long) XDL_HASHLONG(rec->ha, cf->hbits);
104 for (rcrec = cf->rchash[hi]; rcrec; rcrec = rcrec->next)
0d21efa5
JS
105 if (rcrec->ha == rec->ha &&
106 xdl_recmatch(rcrec->line, rcrec->size,
107 rec->ptr, rec->size, cf->flags))
3443546f
LT
108 break;
109
110 if (!rcrec) {
111 if (!(rcrec = xdl_cha_alloc(&cf->ncha))) {
112
113 return -1;
114 }
115 rcrec->idx = cf->count++;
116 rcrec->line = line;
117 rcrec->size = rec->size;
118 rcrec->ha = rec->ha;
119 rcrec->next = cf->rchash[hi];
120 cf->rchash[hi] = rcrec;
121 }
122
123 rec->ha = (unsigned long) rcrec->idx;
124
125 hi = (long) XDL_HASHLONG(rec->ha, hbits);
126 rec->next = rhash[hi];
127 rhash[hi] = rec;
128
129 return 0;
130}
131
132
133static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
134 xdlclassifier_t *cf, xdfile_t *xdf) {
135 unsigned int hbits;
452f4fa5 136 long nrec, hsize, bsize;
3443546f
LT
137 unsigned long hav;
138 char const *blk, *cur, *top, *prev;
139 xrecord_t *crec;
140 xrecord_t **recs, **rrecs;
141 xrecord_t **rhash;
142 unsigned long *ha;
143 char *rchg;
144 long *rindex;
145
146 if (xdl_cha_init(&xdf->rcha, sizeof(xrecord_t), narec / 4 + 1) < 0) {
147
148 return -1;
149 }
150 if (!(recs = (xrecord_t **) xdl_malloc(narec * sizeof(xrecord_t *)))) {
151
152 xdl_cha_free(&xdf->rcha);
153 return -1;
154 }
155
156 hbits = xdl_hashbits((unsigned int) narec);
157 hsize = 1 << hbits;
158 if (!(rhash = (xrecord_t **) xdl_malloc(hsize * sizeof(xrecord_t *)))) {
159
160 xdl_free(recs);
161 xdl_cha_free(&xdf->rcha);
162 return -1;
163 }
452f4fa5 164 memset(rhash, 0, hsize * sizeof(xrecord_t *));
3443546f
LT
165
166 nrec = 0;
167 if ((cur = blk = xdl_mmfile_first(mf, &bsize)) != NULL) {
168 for (top = blk + bsize;;) {
169 if (cur >= top) {
170 if (!(cur = blk = xdl_mmfile_next(mf, &bsize)))
171 break;
172 top = blk + bsize;
173 }
174 prev = cur;
0d21efa5 175 hav = xdl_hash_record(&cur, top, xpp->flags);
3443546f
LT
176 if (nrec >= narec) {
177 narec *= 2;
178 if (!(rrecs = (xrecord_t **) xdl_realloc(recs, narec * sizeof(xrecord_t *)))) {
179
180 xdl_free(rhash);
181 xdl_free(recs);
182 xdl_cha_free(&xdf->rcha);
183 return -1;
184 }
185 recs = rrecs;
186 }
187 if (!(crec = xdl_cha_alloc(&xdf->rcha))) {
188
189 xdl_free(rhash);
190 xdl_free(recs);
191 xdl_cha_free(&xdf->rcha);
192 return -1;
193 }
194 crec->ptr = prev;
195 crec->size = (long) (cur - prev);
196 crec->ha = hav;
197 recs[nrec++] = crec;
198
199 if (xdl_classify_record(cf, rhash, hbits, crec) < 0) {
200
201 xdl_free(rhash);
202 xdl_free(recs);
203 xdl_cha_free(&xdf->rcha);
204 return -1;
205 }
206 }
207 }
208
209 if (!(rchg = (char *) xdl_malloc((nrec + 2) * sizeof(char)))) {
210
211 xdl_free(rhash);
212 xdl_free(recs);
213 xdl_cha_free(&xdf->rcha);
214 return -1;
215 }
216 memset(rchg, 0, (nrec + 2) * sizeof(char));
217
218 if (!(rindex = (long *) xdl_malloc((nrec + 1) * sizeof(long)))) {
219
220 xdl_free(rchg);
221 xdl_free(rhash);
222 xdl_free(recs);
223 xdl_cha_free(&xdf->rcha);
224 return -1;
225 }
226 if (!(ha = (unsigned long *) xdl_malloc((nrec + 1) * sizeof(unsigned long)))) {
227
228 xdl_free(rindex);
229 xdl_free(rchg);
230 xdl_free(rhash);
231 xdl_free(recs);
232 xdl_cha_free(&xdf->rcha);
233 return -1;
234 }
235
236 xdf->nrec = nrec;
237 xdf->recs = recs;
238 xdf->hbits = hbits;
239 xdf->rhash = rhash;
240 xdf->rchg = rchg + 1;
241 xdf->rindex = rindex;
242 xdf->nreff = 0;
243 xdf->ha = ha;
244 xdf->dstart = 0;
245 xdf->dend = nrec - 1;
246
247 return 0;
248}
249
250
251static void xdl_free_ctx(xdfile_t *xdf) {
252
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);
259}
260
261
262int xdl_prepare_env(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
263 xdfenv_t *xe) {
264 long enl1, enl2;
265 xdlclassifier_t cf;
266
267 enl1 = xdl_guess_lines(mf1) + 1;
268 enl2 = xdl_guess_lines(mf2) + 1;
269
0d21efa5 270 if (xdl_init_classifier(&cf, enl1 + enl2 + 1, xpp->flags) < 0) {
3443546f
LT
271
272 return -1;
273 }
274
275 if (xdl_prepare_ctx(mf1, enl1, xpp, &cf, &xe->xdf1) < 0) {
276
277 xdl_free_classifier(&cf);
278 return -1;
279 }
280 if (xdl_prepare_ctx(mf2, enl2, xpp, &cf, &xe->xdf2) < 0) {
281
282 xdl_free_ctx(&xe->xdf1);
283 xdl_free_classifier(&cf);
284 return -1;
285 }
286
287 xdl_free_classifier(&cf);
288
92b7de93
JS
289 if (!(xpp->flags & XDF_PATIENCE_DIFF) &&
290 xdl_optimize_ctxs(&xe->xdf1, &xe->xdf2) < 0) {
3443546f
LT
291
292 xdl_free_ctx(&xe->xdf2);
293 xdl_free_ctx(&xe->xdf1);
294 return -1;
295 }
296
297 return 0;
298}
299
300
301void xdl_free_env(xdfenv_t *xe) {
302
303 xdl_free_ctx(&xe->xdf2);
304 xdl_free_ctx(&xe->xdf1);
305}
306
307
308static int xdl_clean_mmatch(char const *dis, long i, long s, long e) {
ca557aff
DL
309 long r, rdis0, rpdis0, rdis1, rpdis1;
310
9b28d554
DL
311 /*
312 * Limits the window the is examined during the similar-lines
313 * scan. The loops below stops when dis[i - r] == 1 (line that
314 * has no match), but there are corner cases where the loop
315 * proceed all the way to the extremities by causing huge
316 * performance penalties in case of big files.
317 */
318 if (i - s > XDL_SIMSCAN_WINDOW)
319 s = i - XDL_SIMSCAN_WINDOW;
320 if (e - i > XDL_SIMSCAN_WINDOW)
321 e = i + XDL_SIMSCAN_WINDOW;
322
ca557aff
DL
323 /*
324 * Scans the lines before 'i' to find a run of lines that either
325 * have no match (dis[j] == 0) or have multiple matches (dis[j] > 1).
326 * Note that we always call this function with dis[i] > 1, so the
327 * current line (i) is already a multimatch line.
328 */
329 for (r = 1, rdis0 = 0, rpdis0 = 1; (i - r) >= s; r++) {
3443546f 330 if (!dis[i - r])
ca557aff 331 rdis0++;
3443546f 332 else if (dis[i - r] == 2)
ca557aff 333 rpdis0++;
3443546f
LT
334 else
335 break;
336 }
ca557aff
DL
337 /*
338 * If the run before the line 'i' found only multimatch lines, we
339 * return 0 and hence we don't make the current line (i) discarded.
340 * We want to discard multimatch lines only when they appear in the
341 * middle of runs with nomatch lines (dis[j] == 0).
342 */
343 if (rdis0 == 0)
344 return 0;
345 for (r = 1, rdis1 = 0, rpdis1 = 1; (i + r) <= e; r++) {
3443546f 346 if (!dis[i + r])
ca557aff 347 rdis1++;
3443546f 348 else if (dis[i + r] == 2)
ca557aff 349 rpdis1++;
3443546f
LT
350 else
351 break;
352 }
ca557aff
DL
353 /*
354 * If the run after the line 'i' found only multimatch lines, we
355 * return 0 and hence we don't make the current line (i) discarded.
356 */
357 if (rdis1 == 0)
358 return 0;
359 rdis1 += rdis0;
360 rpdis1 += rpdis0;
361
362 return rpdis1 * XDL_KPDIS_RUN < (rpdis1 + rdis1);
3443546f
LT
363}
364
365
366/*
367 * Try to reduce the problem complexity, discard records that have no
368 * matches on the other file. Also, lines that have multiple matches
369 * might be potentially discarded if they happear in a run of discardable.
370 */
371static int xdl_cleanup_records(xdfile_t *xdf1, xdfile_t *xdf2) {
ca557aff 372 long i, nm, rhi, nreff, mlim;
3443546f
LT
373 unsigned long hav;
374 xrecord_t **recs;
375 xrecord_t *rec;
376 char *dis, *dis1, *dis2;
377
ca557aff 378 if (!(dis = (char *) xdl_malloc(xdf1->nrec + xdf2->nrec + 2))) {
3443546f
LT
379
380 return -1;
381 }
ca557aff 382 memset(dis, 0, xdf1->nrec + xdf2->nrec + 2);
3443546f
LT
383 dis1 = dis;
384 dis2 = dis1 + xdf1->nrec + 1;
385
ca557aff
DL
386 if ((mlim = xdl_bogosqrt(xdf1->nrec)) > XDL_MAX_EQLIMIT)
387 mlim = XDL_MAX_EQLIMIT;
3443546f
LT
388 for (i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart]; i <= xdf1->dend; i++, recs++) {
389 hav = (*recs)->ha;
390 rhi = (long) XDL_HASHLONG(hav, xdf2->hbits);
ca557aff
DL
391 for (nm = 0, rec = xdf2->rhash[rhi]; rec; rec = rec->next)
392 if (rec->ha == hav && ++nm == mlim)
3443546f 393 break;
ca557aff 394 dis1[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
3443546f
LT
395 }
396
ca557aff
DL
397 if ((mlim = xdl_bogosqrt(xdf2->nrec)) > XDL_MAX_EQLIMIT)
398 mlim = XDL_MAX_EQLIMIT;
3443546f
LT
399 for (i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart]; i <= xdf2->dend; i++, recs++) {
400 hav = (*recs)->ha;
401 rhi = (long) XDL_HASHLONG(hav, xdf1->hbits);
ca557aff
DL
402 for (nm = 0, rec = xdf1->rhash[rhi]; rec; rec = rec->next)
403 if (rec->ha == hav && ++nm == mlim)
3443546f 404 break;
ca557aff 405 dis2[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
3443546f
LT
406 }
407
408 for (nreff = 0, i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart];
409 i <= xdf1->dend; i++, recs++) {
410 if (dis1[i] == 1 ||
411 (dis1[i] == 2 && !xdl_clean_mmatch(dis1, i, xdf1->dstart, xdf1->dend))) {
412 xdf1->rindex[nreff] = i;
413 xdf1->ha[nreff] = (*recs)->ha;
414 nreff++;
415 } else
416 xdf1->rchg[i] = 1;
417 }
418 xdf1->nreff = nreff;
419
420 for (nreff = 0, i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart];
421 i <= xdf2->dend; i++, recs++) {
422 if (dis2[i] == 1 ||
423 (dis2[i] == 2 && !xdl_clean_mmatch(dis2, i, xdf2->dstart, xdf2->dend))) {
424 xdf2->rindex[nreff] = i;
425 xdf2->ha[nreff] = (*recs)->ha;
426 nreff++;
427 } else
428 xdf2->rchg[i] = 1;
429 }
430 xdf2->nreff = nreff;
431
432 xdl_free(dis);
433
434 return 0;
435}
436
437
438/*
439 * Early trim initial and terminal matching records.
440 */
441static int xdl_trim_ends(xdfile_t *xdf1, xdfile_t *xdf2) {
442 long i, lim;
443 xrecord_t **recs1, **recs2;
444
445 recs1 = xdf1->recs;
446 recs2 = xdf2->recs;
447 for (i = 0, lim = XDL_MIN(xdf1->nrec, xdf2->nrec); i < lim;
448 i++, recs1++, recs2++)
449 if ((*recs1)->ha != (*recs2)->ha)
450 break;
451
452 xdf1->dstart = xdf2->dstart = i;
453
454 recs1 = xdf1->recs + xdf1->nrec - 1;
455 recs2 = xdf2->recs + xdf2->nrec - 1;
456 for (lim -= i, i = 0; i < lim; i++, recs1--, recs2--)
457 if ((*recs1)->ha != (*recs2)->ha)
458 break;
459
460 xdf1->dend = xdf1->nrec - i - 1;
461 xdf2->dend = xdf2->nrec - i - 1;
462
463 return 0;
464}
465
466
467static int xdl_optimize_ctxs(xdfile_t *xdf1, xdfile_t *xdf2) {
468
469 if (xdl_trim_ends(xdf1, xdf2) < 0 ||
470 xdl_cleanup_records(xdf1, xdf2) < 0) {
471
472 return -1;
473 }
474
475 return 0;
476}