xdiff/xprepare: skip classification
[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
159607a8
TRC
146 ha = NULL;
147 rindex = NULL;
148 rchg = NULL;
149 rhash = NULL;
150 recs = NULL;
3443546f 151
159607a8
TRC
152 if (xdl_cha_init(&xdf->rcha, sizeof(xrecord_t), narec / 4 + 1) < 0)
153 goto abort;
154 if (!(recs = (xrecord_t **) xdl_malloc(narec * sizeof(xrecord_t *))))
155 goto abort;
3443546f 156
9f37c275
TRC
157 if (xpp->flags & XDF_HISTOGRAM_DIFF)
158 hbits = hsize = 0;
159 else {
160 hbits = xdl_hashbits((unsigned int) narec);
161 hsize = 1 << hbits;
162 if (!(rhash = (xrecord_t **) xdl_malloc(hsize * sizeof(xrecord_t *))))
163 goto abort;
164 memset(rhash, 0, hsize * sizeof(xrecord_t *));
165 }
3443546f
LT
166
167 nrec = 0;
168 if ((cur = blk = xdl_mmfile_first(mf, &bsize)) != NULL) {
169 for (top = blk + bsize;;) {
170 if (cur >= top) {
171 if (!(cur = blk = xdl_mmfile_next(mf, &bsize)))
172 break;
173 top = blk + bsize;
174 }
175 prev = cur;
0d21efa5 176 hav = xdl_hash_record(&cur, top, xpp->flags);
3443546f
LT
177 if (nrec >= narec) {
178 narec *= 2;
159607a8
TRC
179 if (!(rrecs = (xrecord_t **) xdl_realloc(recs, narec * sizeof(xrecord_t *))))
180 goto abort;
3443546f
LT
181 recs = rrecs;
182 }
159607a8
TRC
183 if (!(crec = xdl_cha_alloc(&xdf->rcha)))
184 goto abort;
3443546f
LT
185 crec->ptr = prev;
186 crec->size = (long) (cur - prev);
187 crec->ha = hav;
188 recs[nrec++] = crec;
189
9f37c275
TRC
190 if (!(xpp->flags & XDF_HISTOGRAM_DIFF) &&
191 xdl_classify_record(cf, rhash, hbits, crec) < 0)
159607a8 192 goto abort;
3443546f
LT
193 }
194 }
195
159607a8
TRC
196 if (!(rchg = (char *) xdl_malloc((nrec + 2) * sizeof(char))))
197 goto abort;
3443546f
LT
198 memset(rchg, 0, (nrec + 2) * sizeof(char));
199
159607a8
TRC
200 if (!(rindex = (long *) xdl_malloc((nrec + 1) * sizeof(long))))
201 goto abort;
202 if (!(ha = (unsigned long *) xdl_malloc((nrec + 1) * sizeof(unsigned long))))
203 goto abort;
3443546f
LT
204
205 xdf->nrec = nrec;
206 xdf->recs = recs;
207 xdf->hbits = hbits;
208 xdf->rhash = rhash;
209 xdf->rchg = rchg + 1;
210 xdf->rindex = rindex;
211 xdf->nreff = 0;
212 xdf->ha = ha;
213 xdf->dstart = 0;
214 xdf->dend = nrec - 1;
215
216 return 0;
159607a8
TRC
217
218abort:
219 xdl_free(ha);
220 xdl_free(rindex);
221 xdl_free(rchg);
222 xdl_free(rhash);
223 xdl_free(recs);
224 xdl_cha_free(&xdf->rcha);
225 return -1;
3443546f
LT
226}
227
228
229static void xdl_free_ctx(xdfile_t *xdf) {
230
231 xdl_free(xdf->rhash);
232 xdl_free(xdf->rindex);
233 xdl_free(xdf->rchg - 1);
234 xdl_free(xdf->ha);
235 xdl_free(xdf->recs);
236 xdl_cha_free(&xdf->rcha);
237}
238
239
240int xdl_prepare_env(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
241 xdfenv_t *xe) {
242 long enl1, enl2;
243 xdlclassifier_t cf;
244
245 enl1 = xdl_guess_lines(mf1) + 1;
246 enl2 = xdl_guess_lines(mf2) + 1;
247
9f37c275
TRC
248 if (!(xpp->flags & XDF_HISTOGRAM_DIFF) &&
249 xdl_init_classifier(&cf, enl1 + enl2 + 1, xpp->flags) < 0) {
3443546f
LT
250
251 return -1;
252 }
253
254 if (xdl_prepare_ctx(mf1, enl1, xpp, &cf, &xe->xdf1) < 0) {
255
256 xdl_free_classifier(&cf);
257 return -1;
258 }
259 if (xdl_prepare_ctx(mf2, enl2, xpp, &cf, &xe->xdf2) < 0) {
260
261 xdl_free_ctx(&xe->xdf1);
262 xdl_free_classifier(&cf);
263 return -1;
264 }
265
9f37c275
TRC
266 if (!(xpp->flags & XDF_HISTOGRAM_DIFF))
267 xdl_free_classifier(&cf);
3443546f 268
92b7de93 269 if (!(xpp->flags & XDF_PATIENCE_DIFF) &&
9f37c275 270 !(xpp->flags & XDF_HISTOGRAM_DIFF) &&
92b7de93 271 xdl_optimize_ctxs(&xe->xdf1, &xe->xdf2) < 0) {
3443546f
LT
272
273 xdl_free_ctx(&xe->xdf2);
274 xdl_free_ctx(&xe->xdf1);
275 return -1;
276 }
277
278 return 0;
279}
280
281
282void xdl_free_env(xdfenv_t *xe) {
283
284 xdl_free_ctx(&xe->xdf2);
285 xdl_free_ctx(&xe->xdf1);
286}
287
288
289static int xdl_clean_mmatch(char const *dis, long i, long s, long e) {
ca557aff
DL
290 long r, rdis0, rpdis0, rdis1, rpdis1;
291
9b28d554
DL
292 /*
293 * Limits the window the is examined during the similar-lines
294 * scan. The loops below stops when dis[i - r] == 1 (line that
295 * has no match), but there are corner cases where the loop
296 * proceed all the way to the extremities by causing huge
297 * performance penalties in case of big files.
298 */
299 if (i - s > XDL_SIMSCAN_WINDOW)
300 s = i - XDL_SIMSCAN_WINDOW;
301 if (e - i > XDL_SIMSCAN_WINDOW)
302 e = i + XDL_SIMSCAN_WINDOW;
303
ca557aff
DL
304 /*
305 * Scans the lines before 'i' to find a run of lines that either
306 * have no match (dis[j] == 0) or have multiple matches (dis[j] > 1).
307 * Note that we always call this function with dis[i] > 1, so the
308 * current line (i) is already a multimatch line.
309 */
310 for (r = 1, rdis0 = 0, rpdis0 = 1; (i - r) >= s; r++) {
3443546f 311 if (!dis[i - r])
ca557aff 312 rdis0++;
3443546f 313 else if (dis[i - r] == 2)
ca557aff 314 rpdis0++;
3443546f
LT
315 else
316 break;
317 }
ca557aff
DL
318 /*
319 * If the run before the line 'i' found only multimatch lines, we
320 * return 0 and hence we don't make the current line (i) discarded.
321 * We want to discard multimatch lines only when they appear in the
322 * middle of runs with nomatch lines (dis[j] == 0).
323 */
324 if (rdis0 == 0)
325 return 0;
326 for (r = 1, rdis1 = 0, rpdis1 = 1; (i + r) <= e; r++) {
3443546f 327 if (!dis[i + r])
ca557aff 328 rdis1++;
3443546f 329 else if (dis[i + r] == 2)
ca557aff 330 rpdis1++;
3443546f
LT
331 else
332 break;
333 }
ca557aff
DL
334 /*
335 * If the run after the line 'i' found only multimatch lines, we
336 * return 0 and hence we don't make the current line (i) discarded.
337 */
338 if (rdis1 == 0)
339 return 0;
340 rdis1 += rdis0;
341 rpdis1 += rpdis0;
342
343 return rpdis1 * XDL_KPDIS_RUN < (rpdis1 + rdis1);
3443546f
LT
344}
345
346
347/*
348 * Try to reduce the problem complexity, discard records that have no
349 * matches on the other file. Also, lines that have multiple matches
350 * might be potentially discarded if they happear in a run of discardable.
351 */
352static int xdl_cleanup_records(xdfile_t *xdf1, xdfile_t *xdf2) {
ca557aff 353 long i, nm, rhi, nreff, mlim;
3443546f
LT
354 unsigned long hav;
355 xrecord_t **recs;
356 xrecord_t *rec;
357 char *dis, *dis1, *dis2;
358
ca557aff 359 if (!(dis = (char *) xdl_malloc(xdf1->nrec + xdf2->nrec + 2))) {
3443546f
LT
360
361 return -1;
362 }
ca557aff 363 memset(dis, 0, xdf1->nrec + xdf2->nrec + 2);
3443546f
LT
364 dis1 = dis;
365 dis2 = dis1 + xdf1->nrec + 1;
366
ca557aff
DL
367 if ((mlim = xdl_bogosqrt(xdf1->nrec)) > XDL_MAX_EQLIMIT)
368 mlim = XDL_MAX_EQLIMIT;
3443546f
LT
369 for (i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart]; i <= xdf1->dend; i++, recs++) {
370 hav = (*recs)->ha;
371 rhi = (long) XDL_HASHLONG(hav, xdf2->hbits);
ca557aff
DL
372 for (nm = 0, rec = xdf2->rhash[rhi]; rec; rec = rec->next)
373 if (rec->ha == hav && ++nm == mlim)
3443546f 374 break;
ca557aff 375 dis1[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
3443546f
LT
376 }
377
ca557aff
DL
378 if ((mlim = xdl_bogosqrt(xdf2->nrec)) > XDL_MAX_EQLIMIT)
379 mlim = XDL_MAX_EQLIMIT;
3443546f
LT
380 for (i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart]; i <= xdf2->dend; i++, recs++) {
381 hav = (*recs)->ha;
382 rhi = (long) XDL_HASHLONG(hav, xdf1->hbits);
ca557aff
DL
383 for (nm = 0, rec = xdf1->rhash[rhi]; rec; rec = rec->next)
384 if (rec->ha == hav && ++nm == mlim)
3443546f 385 break;
ca557aff 386 dis2[i] = (nm == 0) ? 0: (nm >= mlim) ? 2: 1;
3443546f
LT
387 }
388
389 for (nreff = 0, i = xdf1->dstart, recs = &xdf1->recs[xdf1->dstart];
390 i <= xdf1->dend; i++, recs++) {
391 if (dis1[i] == 1 ||
392 (dis1[i] == 2 && !xdl_clean_mmatch(dis1, i, xdf1->dstart, xdf1->dend))) {
393 xdf1->rindex[nreff] = i;
394 xdf1->ha[nreff] = (*recs)->ha;
395 nreff++;
396 } else
397 xdf1->rchg[i] = 1;
398 }
399 xdf1->nreff = nreff;
400
401 for (nreff = 0, i = xdf2->dstart, recs = &xdf2->recs[xdf2->dstart];
402 i <= xdf2->dend; i++, recs++) {
403 if (dis2[i] == 1 ||
404 (dis2[i] == 2 && !xdl_clean_mmatch(dis2, i, xdf2->dstart, xdf2->dend))) {
405 xdf2->rindex[nreff] = i;
406 xdf2->ha[nreff] = (*recs)->ha;
407 nreff++;
408 } else
409 xdf2->rchg[i] = 1;
410 }
411 xdf2->nreff = nreff;
412
413 xdl_free(dis);
414
415 return 0;
416}
417
418
419/*
420 * Early trim initial and terminal matching records.
421 */
422static int xdl_trim_ends(xdfile_t *xdf1, xdfile_t *xdf2) {
423 long i, lim;
424 xrecord_t **recs1, **recs2;
425
426 recs1 = xdf1->recs;
427 recs2 = xdf2->recs;
428 for (i = 0, lim = XDL_MIN(xdf1->nrec, xdf2->nrec); i < lim;
429 i++, recs1++, recs2++)
430 if ((*recs1)->ha != (*recs2)->ha)
431 break;
432
433 xdf1->dstart = xdf2->dstart = i;
434
435 recs1 = xdf1->recs + xdf1->nrec - 1;
436 recs2 = xdf2->recs + xdf2->nrec - 1;
437 for (lim -= i, i = 0; i < lim; i++, recs1--, recs2--)
438 if ((*recs1)->ha != (*recs2)->ha)
439 break;
440
441 xdf1->dend = xdf1->nrec - i - 1;
442 xdf2->dend = xdf2->nrec - i - 1;
443
444 return 0;
445}
446
447
448static int xdl_optimize_ctxs(xdfile_t *xdf1, xdfile_t *xdf2) {
449
450 if (xdl_trim_ends(xdf1, xdf2) < 0 ||
451 xdl_cleanup_records(xdf1, xdf2) < 0) {
452
453 return -1;
454 }
455
456 return 0;
457}