1 /*
2 * Copyright (C) 2010, Google Inc.
3 * and other copyright owners as documented in JGit's IP log.
4 *
5 * This program and the accompanying materials are made available
6 * under the terms of the Eclipse Distribution License v1.0 which
7 * accompanies this distribution, is reproduced below, and is
8 * available at http://www.eclipse.org/org/documents/edl-v10.php
9 *
10 * All rights reserved.
11 *
12 * Redistribution and use in source and binary forms, with or
13 * without modification, are permitted provided that the following
14 * conditions are met:
15 *
16 * - Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 *
19 * - Redistributions in binary form must reproduce the above
20 * copyright notice, this list of conditions and the following
21 * disclaimer in the documentation and/or other materials provided
22 * with the distribution.
23 *
24 * - Neither the name of the Eclipse Foundation, Inc. nor the
25 * names of its contributors may be used to endorse or promote
26 * products derived from this software without specific prior
27 * written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
30 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
31 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
32 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
33 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
34 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
35 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
36 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
37 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
38 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
40 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
41 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
42 */
43
44 #include "xinclude.h"
45 #include "xtypes.h"
46 #include "xdiff.h"
47
48 #define MAX_PTR UINT_MAX
49 #define MAX_CNT UINT_MAX
50
51 #define LINE_END(n) (line##n + count##n - 1)
52 #define LINE_END_PTR(n) (*line##n + *count##n - 1)
53
54 struct histindex {
55 struct record {
56 unsigned int ptr, cnt;
57 struct record *next;
58 } **records, /* an occurrence */
59 **line_map; /* map of line to record chain */
60 chastore_t rcha;
61 unsigned int *next_ptrs;
62 unsigned int table_bits,
63 records_size,
64 line_map_size;
65
66 unsigned int max_chain_length,
67 key_shift,
68 ptr_shift;
69
70 unsigned int cnt,
71 has_common;
72
73 xdfenv_t *env;
74 xpparam_t const *xpp;
75 };
76
77 struct region {
78 unsigned int begin1, end1;
79 unsigned int begin2, end2;
80 };
81
82 #define LINE_MAP(i, a) (i->line_map[(a) - i->ptr_shift])
83
84 #define NEXT_PTR(index, ptr) \
85 (index->next_ptrs[(ptr) - index->ptr_shift])
86
87 #define CNT(index, ptr) \
88 ((LINE_MAP(index, ptr))->cnt)
89
90 #define REC(env, s, l) \
91 (env->xdf##s.recs[l - 1])
92
cmp_recs(xpparam_t const * xpp,xrecord_t * r1,xrecord_t * r2)93 static int cmp_recs(xpparam_t const *xpp,
94 xrecord_t *r1, xrecord_t *r2)
95 {
96 return r1->ha == r2->ha &&
97 xdl_recmatch(r1->ptr, r1->size, r2->ptr, r2->size,
98 xpp->flags);
99 }
100
101 #define CMP_ENV(xpp, env, s1, l1, s2, l2) \
102 (cmp_recs(xpp, REC(env, s1, l1), REC(env, s2, l2)))
103
104 #define CMP(i, s1, l1, s2, l2) \
105 (cmp_recs(i->xpp, REC(i->env, s1, l1), REC(i->env, s2, l2)))
106
107 #define TABLE_HASH(index, side, line) \
108 XDL_HASHLONG((REC(index->env, side, line))->ha, index->table_bits)
109
scanA(struct histindex * index,unsigned int line1,unsigned int count1)110 static int scanA(struct histindex *index, unsigned int line1, unsigned int count1)
111 {
112 unsigned int ptr;
113 unsigned int tbl_idx;
114 unsigned int chain_len;
115 struct record **rec_chain, *rec;
116
117 for (ptr = LINE_END(1); line1 <= ptr; ptr--) {
118 tbl_idx = TABLE_HASH(index, 1, ptr);
119 rec_chain = index->records + tbl_idx;
120 rec = *rec_chain;
121
122 chain_len = 0;
123 while (rec) {
124 if (CMP(index, 1, rec->ptr, 1, ptr)) {
125 /*
126 * ptr is identical to another element. Insert
127 * it onto the front of the existing element
128 * chain.
129 */
130 NEXT_PTR(index, ptr) = rec->ptr;
131 rec->ptr = ptr;
132 /* cap rec->cnt at MAX_CNT */
133 rec->cnt = XDL_MIN(MAX_CNT, rec->cnt + 1);
134 LINE_MAP(index, ptr) = rec;
135 goto continue_scan;
136 }
137
138 rec = rec->next;
139 chain_len++;
140 }
141
142 if (chain_len == index->max_chain_length)
143 return -1;
144
145 /*
146 * This is the first time we have ever seen this particular
147 * element in the sequence. Construct a new chain for it.
148 */
149 if (!(rec = xdl_cha_alloc(&index->rcha)))
150 return -1;
151 rec->ptr = ptr;
152 rec->cnt = 1;
153 rec->next = *rec_chain;
154 *rec_chain = rec;
155 LINE_MAP(index, ptr) = rec;
156
157 continue_scan:
158 ; /* no op */
159 }
160
161 return 0;
162 }
163
try_lcs(struct histindex * index,struct region * lcs,unsigned int b_ptr,unsigned int line1,unsigned int count1,unsigned int line2,unsigned int count2)164 static int try_lcs(
165 struct histindex *index, struct region *lcs, unsigned int b_ptr,
166 unsigned int line1, unsigned int count1,
167 unsigned int line2, unsigned int count2)
168 {
169 unsigned int b_next = b_ptr + 1;
170 struct record *rec = index->records[TABLE_HASH(index, 2, b_ptr)];
171 unsigned int as, ae, bs, be, np, rc;
172 int should_break;
173
174 for (; rec; rec = rec->next) {
175 if (rec->cnt > index->cnt) {
176 if (!index->has_common)
177 index->has_common = CMP(index, 1, rec->ptr, 2, b_ptr);
178 continue;
179 }
180
181 as = rec->ptr;
182 if (!CMP(index, 1, as, 2, b_ptr))
183 continue;
184
185 index->has_common = 1;
186 for (;;) {
187 should_break = 0;
188 np = NEXT_PTR(index, as);
189 bs = b_ptr;
190 ae = as;
191 be = bs;
192 rc = rec->cnt;
193
194 while (line1 < as && line2 < bs
195 && CMP(index, 1, as - 1, 2, bs - 1)) {
196 as--;
197 bs--;
198 if (1 < rc)
199 rc = XDL_MIN(rc, CNT(index, as));
200 }
201 while (ae < LINE_END(1) && be < LINE_END(2)
202 && CMP(index, 1, ae + 1, 2, be + 1)) {
203 ae++;
204 be++;
205 if (1 < rc)
206 rc = XDL_MIN(rc, CNT(index, ae));
207 }
208
209 if (b_next <= be)
210 b_next = be + 1;
211 if (lcs->end1 - lcs->begin1 < ae - as || rc < index->cnt) {
212 lcs->begin1 = as;
213 lcs->begin2 = bs;
214 lcs->end1 = ae;
215 lcs->end2 = be;
216 index->cnt = rc;
217 }
218
219 if (np == 0)
220 break;
221
222 while (np <= ae) {
223 np = NEXT_PTR(index, np);
224 if (np == 0) {
225 should_break = 1;
226 break;
227 }
228 }
229
230 if (should_break)
231 break;
232
233 as = np;
234 }
235 }
236 return b_next;
237 }
238
find_lcs(struct histindex * index,struct region * lcs,unsigned int line1,unsigned int count1,unsigned int line2,unsigned int count2)239 static int find_lcs(
240 struct histindex *index, struct region *lcs,
241 unsigned int line1, unsigned int count1,
242 unsigned int line2, unsigned int count2)
243 {
244 unsigned int b_ptr;
245
246 if (scanA(index, line1, count1))
247 return -1;
248
249 index->cnt = index->max_chain_length + 1;
250
251 for (b_ptr = line2; b_ptr <= LINE_END(2); )
252 b_ptr = try_lcs(index, lcs, b_ptr, line1, count1, line2, count2);
253
254 return index->has_common && index->max_chain_length < index->cnt;
255 }
256
fall_back_to_classic_diff(struct histindex * index,int line1,int count1,int line2,int count2)257 static int fall_back_to_classic_diff(struct histindex *index,
258 int line1, int count1, int line2, int count2)
259 {
260 xpparam_t xpp;
261 xpp.flags = index->xpp->flags & ~XDF_DIFF_ALGORITHM_MASK;
262
263 return xdl_fall_back_diff(index->env, &xpp,
264 line1, count1, line2, count2);
265 }
266
histogram_diff(xpparam_t const * xpp,xdfenv_t * env,unsigned int line1,unsigned int count1,unsigned int line2,unsigned int count2)267 static int histogram_diff(
268 xpparam_t const *xpp, xdfenv_t *env,
269 unsigned int line1, unsigned int count1,
270 unsigned int line2, unsigned int count2)
271 {
272 struct histindex index;
273 struct region lcs;
274 size_t sz;
275 int result = -1;
276
277 if (count1 <= 0 && count2 <= 0)
278 return 0;
279
280 if (LINE_END(1) >= MAX_PTR)
281 return -1;
282
283 if (!count1) {
284 while(count2--)
285 env->xdf2.rchg[line2++ - 1] = 1;
286 return 0;
287 } else if (!count2) {
288 while(count1--)
289 env->xdf1.rchg[line1++ - 1] = 1;
290 return 0;
291 }
292
293 memset(&index, 0, sizeof(index));
294
295 index.env = env;
296 index.xpp = xpp;
297
298 index.records = NULL;
299 index.line_map = NULL;
300 /* in case of early xdl_cha_free() */
301 index.rcha.head = NULL;
302
303 index.table_bits = xdl_hashbits(count1);
304 sz = index.records_size = 1 << index.table_bits;
305 GIT_ERROR_CHECK_ALLOC_MULTIPLY(&sz, sz, sizeof(struct record *));
306
307 if (!(index.records = (struct record **) xdl_malloc(sz)))
308 goto cleanup;
309 memset(index.records, 0, sz);
310
311 sz = index.line_map_size = count1;
312 sz *= sizeof(struct record *);
313 if (!(index.line_map = (struct record **) xdl_malloc(sz)))
314 goto cleanup;
315 memset(index.line_map, 0, sz);
316
317 sz = index.line_map_size;
318 sz *= sizeof(unsigned int);
319 if (!(index.next_ptrs = (unsigned int *) xdl_malloc(sz)))
320 goto cleanup;
321 memset(index.next_ptrs, 0, sz);
322
323 /* lines / 4 + 1 comes from xprepare.c:xdl_prepare_ctx() */
324 if (xdl_cha_init(&index.rcha, sizeof(struct record), count1 / 4 + 1) < 0)
325 goto cleanup;
326
327 index.ptr_shift = line1;
328 index.max_chain_length = 64;
329
330 memset(&lcs, 0, sizeof(lcs));
331 if (find_lcs(&index, &lcs, line1, count1, line2, count2))
332 result = fall_back_to_classic_diff(&index, line1, count1, line2, count2);
333 else {
334 if (lcs.begin1 == 0 && lcs.begin2 == 0) {
335 while (count1--)
336 env->xdf1.rchg[line1++ - 1] = 1;
337 while (count2--)
338 env->xdf2.rchg[line2++ - 1] = 1;
339 result = 0;
340 } else {
341 result = histogram_diff(xpp, env,
342 line1, lcs.begin1 - line1,
343 line2, lcs.begin2 - line2);
344 if (result)
345 goto cleanup;
346 result = histogram_diff(xpp, env,
347 lcs.end1 + 1, LINE_END(1) - lcs.end1,
348 lcs.end2 + 1, LINE_END(2) - lcs.end2);
349 if (result)
350 goto cleanup;
351 }
352 }
353
354 cleanup:
355 xdl_free(index.records);
356 xdl_free(index.line_map);
357 xdl_free(index.next_ptrs);
358 xdl_cha_free(&index.rcha);
359
360 return result;
361 }
362
xdl_do_histogram_diff(mmfile_t * file1,mmfile_t * file2,xpparam_t const * xpp,xdfenv_t * env)363 int xdl_do_histogram_diff(mmfile_t *file1, mmfile_t *file2,
364 xpparam_t const *xpp, xdfenv_t *env)
365 {
366 if (xdl_prepare_env(file1, file2, xpp, env) < 0)
367 return -1;
368
369 return histogram_diff(xpp, env,
370 env->xdf1.dstart + 1, env->xdf1.dend - env->xdf1.dstart + 1,
371 env->xdf2.dstart + 1, env->xdf2.dend - env->xdf2.dstart + 1);
372 }
373