Sync with "maint"
[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) {
3443546f
LT
67 long i;
68
0d21efa5
JS
69 cf->flags = flags;
70
3443546f
LT
71 cf->hbits = xdl_hashbits((unsigned int) size);
72 cf->hsize = 1 << cf->hbits;
73
74 if (xdl_cha_init(&cf->ncha, sizeof(xdlclass_t), size / 4 + 1) < 0) {
75
76 return -1;
77 }
78 if (!(cf->rchash = (xdlclass_t **) xdl_malloc(cf->hsize * sizeof(xdlclass_t *)))) {
79
80 xdl_cha_free(&cf->ncha);
81 return -1;
82 }
83 for (i = 0; i < cf->hsize; i++)
84 cf->rchash[i] = NULL;
85
86 cf->count = 0;
87
88 return 0;
89}
90
91
92static void xdl_free_classifier(xdlclassifier_t *cf) {
93
94 xdl_free(cf->rchash);
95 xdl_cha_free(&cf->ncha);
96}
97
98
99static int xdl_classify_record(xdlclassifier_t *cf, xrecord_t **rhash, unsigned int hbits,
100 xrecord_t *rec) {
101 long hi;
102 char const *line;
103 xdlclass_t *rcrec;
104
105 line = rec->ptr;
106 hi = (long) XDL_HASHLONG(rec->ha, cf->hbits);
107 for (rcrec = cf->rchash[hi]; rcrec; rcrec = rcrec->next)
0d21efa5
JS
108 if (rcrec->ha == rec->ha &&
109 xdl_recmatch(rcrec->line, rcrec->size,
110 rec->ptr, rec->size, cf->flags))
3443546f
LT
111 break;
112
113 if (!rcrec) {
114 if (!(rcrec = xdl_cha_alloc(&cf->ncha))) {
115
116 return -1;
117 }
118 rcrec->idx = cf->count++;
119 rcrec->line = line;
120 rcrec->size = rec->size;
121 rcrec->ha = rec->ha;
122 rcrec->next = cf->rchash[hi];
123 cf->rchash[hi] = rcrec;
124 }
125
126 rec->ha = (unsigned long) rcrec->idx;
127
128 hi = (long) XDL_HASHLONG(rec->ha, hbits);
129 rec->next = rhash[hi];
130 rhash[hi] = rec;
131
132 return 0;
133}
134
135
136static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
137 xdlclassifier_t *cf, xdfile_t *xdf) {
138 unsigned int hbits;
139 long i, nrec, hsize, bsize;
140 unsigned long hav;
141 char const *blk, *cur, *top, *prev;
142 xrecord_t *crec;
143 xrecord_t **recs, **rrecs;
144 xrecord_t **rhash;
145 unsigned long *ha;
146 char *rchg;
147 long *rindex;
148
149 if (xdl_cha_init(&xdf->rcha, sizeof(xrecord_t), narec / 4 + 1) < 0) {
150
151 return -1;
152 }
153 if (!(recs = (xrecord_t **) xdl_malloc(narec * sizeof(xrecord_t *)))) {
154
155 xdl_cha_free(&xdf->rcha);
156 return -1;
157 }
158
159 hbits = xdl_hashbits((unsigned int) narec);
160 hsize = 1 << hbits;
161 if (!(rhash = (xrecord_t **) xdl_malloc(hsize * sizeof(xrecord_t *)))) {
162
163 xdl_free(recs);
164 xdl_cha_free(&xdf->rcha);
165 return -1;
166 }
167 for (i = 0; i < hsize; i++)
168 rhash[i] = NULL;
169
170 nrec = 0;
171 if ((cur = blk = xdl_mmfile_first(mf, &bsize)) != NULL) {
172 for (top = blk + bsize;;) {
173 if (cur >= top) {
174 if (!(cur = blk = xdl_mmfile_next(mf, &bsize)))
175 break;
176 top = blk + bsize;
177 }
178 prev = cur;
0d21efa5 179 hav = xdl_hash_record(&cur, top, xpp->flags);
3443546f
LT
180 if (nrec >= narec) {
181 narec *= 2;
182 if (!(rrecs = (xrecord_t **) xdl_realloc(recs, narec * sizeof(xrecord_t *)))) {
183
184 xdl_free(rhash);
185 xdl_free(recs);
186 xdl_cha_free(&xdf->rcha);
187 return -1;
188 }
189 recs = rrecs;
190 }
191 if (!(crec = xdl_cha_alloc(&xdf->rcha))) {
192
193 xdl_free(rhash);
194 xdl_free(recs);
195 xdl_cha_free(&xdf->rcha);
196 return -1;
197 }
198 crec->ptr = prev;
199 crec->size = (long) (cur - prev);
200 crec->ha = hav;
201 recs[nrec++] = crec;
202
203 if (xdl_classify_record(cf, rhash, hbits, crec) < 0) {
204
205 xdl_free(rhash);
206 xdl_free(recs);
207 xdl_cha_free(&xdf->rcha);
208 return -1;
209 }
210 }
211 }
212
213 if (!(rchg = (char *) xdl_malloc((nrec + 2) * sizeof(char)))) {
214
215 xdl_free(rhash);
216 xdl_free(recs);
217 xdl_cha_free(&xdf->rcha);
218 return -1;
219 }
220 memset(rchg, 0, (nrec + 2) * sizeof(char));
221
222 if (!(rindex = (long *) xdl_malloc((nrec + 1) * sizeof(long)))) {
223
224 xdl_free(rchg);
225 xdl_free(rhash);
226 xdl_free(recs);
227 xdl_cha_free(&xdf->rcha);
228 return -1;
229 }
230 if (!(ha = (unsigned long *) xdl_malloc((nrec + 1) * sizeof(unsigned long)))) {
231
232 xdl_free(rindex);
233 xdl_free(rchg);
234 xdl_free(rhash);
235 xdl_free(recs);
236 xdl_cha_free(&xdf->rcha);
237 return -1;
238 }
239
240 xdf->nrec = nrec;
241 xdf->recs = recs;
242 xdf->hbits = hbits;
243 xdf->rhash = rhash;
244 xdf->rchg = rchg + 1;
245 xdf->rindex = rindex;
246 xdf->nreff = 0;
247 xdf->ha = ha;
248 xdf->dstart = 0;
249 xdf->dend = nrec - 1;
250
251 return 0;
252}
253
254
255static void xdl_free_ctx(xdfile_t *xdf) {
256
257 xdl_free(xdf->rhash);
258 xdl_free(xdf->rindex);
259 xdl_free(xdf->rchg - 1);
260 xdl_free(xdf->ha);
261 xdl_free(xdf->recs);
262 xdl_cha_free(&xdf->rcha);
263}
264
265
266int xdl_prepare_env(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
267 xdfenv_t *xe) {
268 long enl1, enl2;
269 xdlclassifier_t cf;
270
271 enl1 = xdl_guess_lines(mf1) + 1;
272 enl2 = xdl_guess_lines(mf2) + 1;
273
0d21efa5 274 if (xdl_init_classifier(&cf, enl1 + enl2 + 1, xpp->flags) < 0) {
3443546f
LT
275
276 return -1;
277 }
278
279 if (xdl_prepare_ctx(mf1, enl1, xpp, &cf, &xe->xdf1) < 0) {
280
281 xdl_free_classifier(&cf);
282 return -1;
283 }
284 if (xdl_prepare_ctx(mf2, enl2, xpp, &cf, &xe->xdf2) < 0) {
285
286 xdl_free_ctx(&xe->xdf1);
287 xdl_free_classifier(&cf);
288 return -1;
289 }
290
291 xdl_free_classifier(&cf);
292
92b7de93
JS
293 if (!(xpp->flags & XDF_PATIENCE_DIFF) &&
294 xdl_optimize_ctxs(&xe->xdf1, &xe->xdf2) < 0) {
3443546f
LT
295
296 xdl_free_ctx(&xe->xdf2);
297 xdl_free_ctx(&xe->xdf1);
298 return -1;
299 }
300
301 return 0;
302}
303
304
305void xdl_free_env(xdfenv_t *xe) {
306
307 xdl_free_ctx(&xe->xdf2);
308 xdl_free_ctx(&xe->xdf1);
309}
310
311
312static int xdl_clean_mmatch(char const *dis, long i, long s, long e) {
ca557aff
DL
313 long r, rdis0, rpdis0, rdis1, rpdis1;
314
9b28d554
DL
315 /*
316 * Limits the window the is examined during the similar-lines
317 * scan. The loops below stops when dis[i - r] == 1 (line that
318 * has no match), but there are corner cases where the loop
319 * proceed all the way to the extremities by causing huge
320 * performance penalties in case of big files.
321 */
322 if (i - s > XDL_SIMSCAN_WINDOW)
323 s = i - XDL_SIMSCAN_WINDOW;
324 if (e - i > XDL_SIMSCAN_WINDOW)
325 e = i + XDL_SIMSCAN_WINDOW;
326
ca557aff
DL
327 /*
328 * Scans the lines before 'i' to find a run of lines that either
329 * have no match (dis[j] == 0) or have multiple matches (dis[j] > 1).
330 * Note that we always call this function with dis[i] > 1, so the
331 * current line (i) is already a multimatch line.
332 */
333 for (r = 1, rdis0 = 0, rpdis0 = 1; (i - r) >= s; r++) {
3443546f 334 if (!dis[i - r])
ca557aff 335 rdis0++;
3443546f 336 else if (dis[i - r] == 2)
ca557aff 337 rpdis0++;
3443546f
LT
338 else
339 break;
340 }
ca557aff
DL
341 /*
342 * If the run before the line 'i' found only multimatch lines, we
343 * return 0 and hence we don't make the current line (i) discarded.
344 * We want to discard multimatch lines only when they appear in the
345 * middle of runs with nomatch lines (dis[j] == 0).
346 */
347 if (rdis0 == 0)
348 return 0;
349 for (r = 1, rdis1 = 0, rpdis1 = 1; (i + r) <= e; r++) {
3443546f 350 if (!dis[i + r])
ca557aff 351 rdis1++;
3443546f 352 else if (dis[i + r] == 2)
ca557aff 353 rpdis1++;
3443546f
LT
354 else
355 break;
356 }
ca557aff
DL
357 /*
358 * If the run after the line 'i' found only multimatch lines, we
359 * return 0 and hence we don't make the current line (i) discarded.
360 */
361 if (rdis1 == 0)
362 return 0;
363 rdis1 += rdis0;
364 rpdis1 += rpdis0;
365
366 return rpdis1 * XDL_KPDIS_RUN < (rpdis1 + rdis1);
3443546f
LT
367}
368
369
370/*
371 * Try to reduce the problem complexity, discard records that have no
372 * matches on the other file. Also, lines that have multiple matches
373 * might be potentially discarded if they happear in a run of discardable.
374 */
375static int xdl_cleanup_records(xdfile_t *xdf1, xdfile_t *xdf2) {
ca557aff 376 long i, nm, rhi, nreff, mlim;
3443546f
LT
377 unsigned long hav;
378 xrecord_t **recs;
379 xrecord_t *rec;
380 char *dis, *dis1, *dis2;
381
ca557aff 382 if (!(dis = (char *) xdl_malloc(xdf1->nrec + xdf2->nrec + 2))) {
3443546f
LT
383
384 return -1;
385 }
ca557aff 386 memset(dis, 0, xdf1->nrec + xdf2->nrec + 2);
3443546f
LT
387 dis1 = dis;
388 dis2 = dis1 + xdf1->nrec + 1;
389
ca557aff
DL
390 if ((mlim = xdl_bogosqrt(xdf1->nrec)) > XDL_MAX_EQLIMIT)
391 mlim = XDL_MAX_EQLIMIT;
3443546f
LT
392 for (i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart]; i <= xdf1->dend; i++, recs++) {
393 hav = (*recs)->ha;
394 rhi = (long) XDL_HASHLONG(hav, xdf2->hbits);
ca557aff
DL
395 for (nm = 0, rec = xdf2->rhash[rhi]; rec; rec = rec->next)
396 if (rec->ha == hav && ++nm == mlim)
3443546f 397 break;
ca557aff 398 dis1[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
3443546f
LT
399 }
400
ca557aff
DL
401 if ((mlim = xdl_bogosqrt(xdf2->nrec)) > XDL_MAX_EQLIMIT)
402 mlim = XDL_MAX_EQLIMIT;
3443546f
LT
403 for (i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart]; i <= xdf2->dend; i++, recs++) {
404 hav = (*recs)->ha;
405 rhi = (long) XDL_HASHLONG(hav, xdf1->hbits);
ca557aff
DL
406 for (nm = 0, rec = xdf1->rhash[rhi]; rec; rec = rec->next)
407 if (rec->ha == hav && ++nm == mlim)
3443546f 408 break;
ca557aff 409 dis2[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
3443546f
LT
410 }
411
412 for (nreff = 0, i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart];
413 i <= xdf1->dend; i++, recs++) {
414 if (dis1[i] == 1 ||
415 (dis1[i] == 2 && !xdl_clean_mmatch(dis1, i, xdf1->dstart, xdf1->dend))) {
416 xdf1->rindex[nreff] = i;
417 xdf1->ha[nreff] = (*recs)->ha;
418 nreff++;
419 } else
420 xdf1->rchg[i] = 1;
421 }
422 xdf1->nreff = nreff;
423
424 for (nreff = 0, i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart];
425 i <= xdf2->dend; i++, recs++) {
426 if (dis2[i] == 1 ||
427 (dis2[i] == 2 && !xdl_clean_mmatch(dis2, i, xdf2->dstart, xdf2->dend))) {
428 xdf2->rindex[nreff] = i;
429 xdf2->ha[nreff] = (*recs)->ha;
430 nreff++;
431 } else
432 xdf2->rchg[i] = 1;
433 }
434 xdf2->nreff = nreff;
435
436 xdl_free(dis);
437
438 return 0;
439}
440
441
442/*
443 * Early trim initial and terminal matching records.
444 */
445static int xdl_trim_ends(xdfile_t *xdf1, xdfile_t *xdf2) {
446 long i, lim;
447 xrecord_t **recs1, **recs2;
448
449 recs1 = xdf1->recs;
450 recs2 = xdf2->recs;
451 for (i = 0, lim = XDL_MIN(xdf1->nrec, xdf2->nrec); i < lim;
452 i++, recs1++, recs2++)
453 if ((*recs1)->ha != (*recs2)->ha)
454 break;
455
456 xdf1->dstart = xdf2->dstart = i;
457
458 recs1 = xdf1->recs + xdf1->nrec - 1;
459 recs2 = xdf2->recs + xdf2->nrec - 1;
460 for (lim -= i, i = 0; i < lim; i++, recs1--, recs2--)
461 if ((*recs1)->ha != (*recs2)->ha)
462 break;
463
464 xdf1->dend = xdf1->nrec - i - 1;
465 xdf2->dend = xdf2->nrec - i - 1;
466
467 return 0;
468}
469
470
471static int xdl_optimize_ctxs(xdfile_t *xdf1, xdfile_t *xdf2) {
472
473 if (xdl_trim_ends(xdf1, xdf2) < 0 ||
474 xdl_cleanup_records(xdf1, xdf2) < 0) {
475
476 return -1;
477 }
478
479 return 0;
480}