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
46 #define MAX_PTR INT_MAX
47 #define MAX_CNT INT_MAX
48
49 #define LINE_END(n) (line##n + count##n - 1)
50 #define LINE_END_PTR(n) (*line##n + *count##n - 1)
51
52 struct histindex {
53 struct record {
54 unsigned int ptr, cnt;
55 struct record *next;
56 } **records, /* an occurrence */
57 **line_map; /* map of line to record chain */
58 chastore_t rcha;
59 unsigned int *next_ptrs;
60 unsigned int table_bits,
61 records_size,
62 line_map_size;
63
64 unsigned int max_chain_length,
65 key_shift,
66 ptr_shift;
67
68 unsigned int cnt,
69 has_common;
70
71 xdfenv_t *env;
72 xpparam_t const *xpp;
73 };
74
75 struct region {
76 unsigned int begin1, end1;
77 unsigned int begin2, end2;
78 };
79
80 #define LINE_MAP(i, a) (i->line_map[(a) - i->ptr_shift])
81
82 #define NEXT_PTR(index, ptr) \
83 (index->next_ptrs[(ptr) - index->ptr_shift])
84
85 #define CNT(index, ptr) \
86 ((LINE_MAP(index, ptr))->cnt)
87
88 #define REC(env, s, l) \
89 (env->xdf##s.recs[l - 1])
90
cmp_recs(xpparam_t const * xpp,xrecord_t * r1,xrecord_t * r2)91 static int cmp_recs(xpparam_t const *xpp,
92 xrecord_t *r1, xrecord_t *r2)
93 {
94 return r1->ha == r2->ha &&
95 xdl_recmatch(r1->ptr, r1->size, r2->ptr, r2->size,
96 xpp->flags);
97 }
98
99 #define CMP_ENV(xpp, env, s1, l1, s2, l2) \
100 (cmp_recs(xpp, REC(env, s1, l1), REC(env, s2, l2)))
101
102 #define CMP(i, s1, l1, s2, l2) \
103 (cmp_recs(i->xpp, REC(i->env, s1, l1), REC(i->env, s2, l2)))
104
105 #define TABLE_HASH(index, side, line) \
106 XDL_HASHLONG((REC(index->env, side, line))->ha, index->table_bits)
107
scanA(struct histindex * index,int line1,int count1)108 static int scanA(struct histindex *index, int line1, int count1)
109 {
110 int ptr, tbl_idx;
111 unsigned int chain_len;
112 struct record **rec_chain, *rec;
113
114 for (ptr = LINE_END(1); line1 <= ptr; ptr--) {
115 tbl_idx = TABLE_HASH(index, 1, ptr);
116 rec_chain = index->records + tbl_idx;
117 rec = *rec_chain;
118
119 chain_len = 0;
120 while (rec) {
121 if (CMP(index, 1, rec->ptr, 1, ptr)) {
122 /*
123 * ptr is identical to another element. Insert
124 * it onto the front of the existing element
125 * chain.
126 */
127 NEXT_PTR(index, ptr) = rec->ptr;
128 rec->ptr = ptr;
129 /* cap rec->cnt at MAX_CNT */
130 rec->cnt = XDL_MIN(MAX_CNT, rec->cnt + 1);
131 LINE_MAP(index, ptr) = rec;
132 goto continue_scan;
133 }
134
135 rec = rec->next;
136 chain_len++;
137 }
138
139 if (chain_len == index->max_chain_length)
140 return -1;
141
142 /*
143 * This is the first time we have ever seen this particular
144 * element in the sequence. Construct a new chain for it.
145 */
146 if (!(rec = xdl_cha_alloc(&index->rcha)))
147 return -1;
148 rec->ptr = ptr;
149 rec->cnt = 1;
150 rec->next = *rec_chain;
151 *rec_chain = rec;
152 LINE_MAP(index, ptr) = rec;
153
154 continue_scan:
155 ; /* no op */
156 }
157
158 return 0;
159 }
160
try_lcs(struct histindex * index,struct region * lcs,int b_ptr,int line1,int count1,int line2,int count2)161 static int try_lcs(struct histindex *index, struct region *lcs, int b_ptr,
162 int line1, int count1, int line2, int count2)
163 {
164 unsigned int b_next = b_ptr + 1;
165 struct record *rec = index->records[TABLE_HASH(index, 2, b_ptr)];
166 unsigned int as, ae, bs, be, np, rc;
167 int should_break;
168
169 for (; rec; rec = rec->next) {
170 if (rec->cnt > index->cnt) {
171 if (!index->has_common)
172 index->has_common = CMP(index, 1, rec->ptr, 2, b_ptr);
173 continue;
174 }
175
176 as = rec->ptr;
177 if (!CMP(index, 1, as, 2, b_ptr))
178 continue;
179
180 index->has_common = 1;
181 for (;;) {
182 should_break = 0;
183 np = NEXT_PTR(index, as);
184 bs = b_ptr;
185 ae = as;
186 be = bs;
187 rc = rec->cnt;
188
189 while (line1 < (int)as && line2 < (int)bs
190 && CMP(index, 1, as - 1, 2, bs - 1)) {
191 as--;
192 bs--;
193 if (1 < rc)
194 rc = XDL_MIN(rc, CNT(index, as));
195 }
196 while ((int)ae < LINE_END(1) && (int)be < LINE_END(2)
197 && CMP(index, 1, ae + 1, 2, be + 1)) {
198 ae++;
199 be++;
200 if (1 < rc)
201 rc = XDL_MIN(rc, CNT(index, ae));
202 }
203
204 if (b_next <= be)
205 b_next = be + 1;
206 if (lcs->end1 - lcs->begin1 < ae - as || rc < index->cnt) {
207 lcs->begin1 = as;
208 lcs->begin2 = bs;
209 lcs->end1 = ae;
210 lcs->end2 = be;
211 index->cnt = rc;
212 }
213
214 if (np == 0)
215 break;
216
217 while (np <= ae) {
218 np = NEXT_PTR(index, np);
219 if (np == 0) {
220 should_break = 1;
221 break;
222 }
223 }
224
225 if (should_break)
226 break;
227
228 as = np;
229 }
230 }
231 return b_next;
232 }
233
fall_back_to_classic_diff(xpparam_t const * xpp,xdfenv_t * env,int line1,int count1,int line2,int count2)234 static int fall_back_to_classic_diff(xpparam_t const *xpp, xdfenv_t *env,
235 int line1, int count1, int line2, int count2)
236 {
237 xpparam_t xpparam;
238
239 memset(&xpparam, 0, sizeof(xpparam));
240 xpparam.flags = xpp->flags & ~XDF_DIFF_ALGORITHM_MASK;
241
242 return xdl_fall_back_diff(env, &xpparam,
243 line1, count1, line2, count2);
244 }
245
free_index(struct histindex * index)246 static inline void free_index(struct histindex *index)
247 {
248 xdl_free(index->records);
249 xdl_free(index->line_map);
250 xdl_free(index->next_ptrs);
251 xdl_cha_free(&index->rcha);
252 }
253
find_lcs(xpparam_t const * xpp,xdfenv_t * env,struct region * lcs,int line1,int count1,int line2,int count2)254 static int find_lcs(xpparam_t const *xpp, xdfenv_t *env,
255 struct region *lcs,
256 int line1, int count1, int line2, int count2)
257 {
258 int b_ptr;
259 int sz, ret = -1;
260 struct histindex index;
261
262 memset(&index, 0, sizeof(index));
263
264 index.env = env;
265 index.xpp = xpp;
266
267 index.records = NULL;
268 index.line_map = NULL;
269 /* in case of early xdl_cha_free() */
270 index.rcha.head = NULL;
271
272 index.table_bits = xdl_hashbits(count1);
273 sz = index.records_size = 1 << index.table_bits;
274 sz *= sizeof(struct record *);
275 if (!(index.records = (struct record **) xdl_malloc(sz)))
276 goto cleanup;
277 memset(index.records, 0, sz);
278
279 sz = index.line_map_size = count1;
280 sz *= sizeof(struct record *);
281 if (!(index.line_map = (struct record **) xdl_malloc(sz)))
282 goto cleanup;
283 memset(index.line_map, 0, sz);
284
285 sz = index.line_map_size;
286 sz *= sizeof(unsigned int);
287 if (!(index.next_ptrs = (unsigned int *) xdl_malloc(sz)))
288 goto cleanup;
289 memset(index.next_ptrs, 0, sz);
290
291 /* lines / 4 + 1 comes from xprepare.c:xdl_prepare_ctx() */
292 if (xdl_cha_init(&index.rcha, sizeof(struct record), count1 / 4 + 1) < 0)
293 goto cleanup;
294
295 index.ptr_shift = line1;
296 index.max_chain_length = 64;
297
298 if (scanA(&index, line1, count1))
299 goto cleanup;
300
301 index.cnt = index.max_chain_length + 1;
302
303 for (b_ptr = line2; b_ptr <= LINE_END(2); )
304 b_ptr = try_lcs(&index, lcs, b_ptr, line1, count1, line2, count2);
305
306 if (index.has_common && index.max_chain_length < index.cnt)
307 ret = 1;
308 else
309 ret = 0;
310
311 cleanup:
312 free_index(&index);
313 return ret;
314 }
315
histogram_diff(xpparam_t const * xpp,xdfenv_t * env,int line1,int count1,int line2,int count2)316 static int histogram_diff(xpparam_t const *xpp, xdfenv_t *env,
317 int line1, int count1, int line2, int count2)
318 {
319 struct region lcs;
320 int lcs_found;
321 int result;
322 redo:
323 result = -1;
324
325 if (count1 <= 0 && count2 <= 0)
326 return 0;
327
328 if (LINE_END(1) >= MAX_PTR)
329 return -1;
330
331 if (!count1) {
332 while(count2--)
333 env->xdf2.rchg[line2++ - 1] = 1;
334 return 0;
335 } else if (!count2) {
336 while(count1--)
337 env->xdf1.rchg[line1++ - 1] = 1;
338 return 0;
339 }
340
341 memset(&lcs, 0, sizeof(lcs));
342 lcs_found = find_lcs(xpp, env, &lcs, line1, count1, line2, count2);
343 if (lcs_found < 0)
344 goto out;
345 else if (lcs_found)
346 result = fall_back_to_classic_diff(xpp, env, line1, count1, line2, count2);
347 else {
348 if (lcs.begin1 == 0 && lcs.begin2 == 0) {
349 while (count1--)
350 env->xdf1.rchg[line1++ - 1] = 1;
351 while (count2--)
352 env->xdf2.rchg[line2++ - 1] = 1;
353 result = 0;
354 } else {
355 result = histogram_diff(xpp, env,
356 line1, lcs.begin1 - line1,
357 line2, lcs.begin2 - line2);
358 if (result)
359 goto out;
360 /*
361 * result = histogram_diff(xpp, env,
362 * lcs.end1 + 1, LINE_END(1) - lcs.end1,
363 * lcs.end2 + 1, LINE_END(2) - lcs.end2);
364 * but let's optimize tail recursion ourself:
365 */
366 count1 = LINE_END(1) - lcs.end1;
367 line1 = lcs.end1 + 1;
368 count2 = LINE_END(2) - lcs.end2;
369 line2 = lcs.end2 + 1;
370 goto redo;
371 }
372 }
373 out:
374 return result;
375 }
376
xdl_do_histogram_diff(mmfile_t * file1,mmfile_t * file2,xpparam_t const * xpp,xdfenv_t * env)377 int xdl_do_histogram_diff(mmfile_t *file1, mmfile_t *file2,
378 xpparam_t const *xpp, xdfenv_t *env)
379 {
380 if (xdl_prepare_env(file1, file2, xpp, env) < 0)
381 return -1;
382
383 return histogram_diff(xpp, env,
384 env->xdf1.dstart + 1, env->xdf1.dend - env->xdf1.dstart + 1,
385 env->xdf2.dstart + 1, env->xdf2.dend - env->xdf2.dstart + 1);
386 }
387