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8c912eea TRC |
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" | |
8c912eea TRC |
45 | |
46 | #define MAX_PTR UINT_MAX | |
47 | #define MAX_CNT UINT_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; | |
41ccfdd9 | 56 | } **records, /* an occurrence */ |
8c912eea TRC |
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 | ||
25449450 | 91 | static int cmp_recs(xrecord_t *r1, xrecord_t *r2) |
8c912eea | 92 | { |
663c5ad0 PW |
93 | return r1->ha == r2->ha; |
94 | ||
8c912eea TRC |
95 | } |
96 | ||
8c912eea | 97 | #define CMP(i, s1, l1, s2, l2) \ |
25449450 | 98 | (cmp_recs(REC(i->env, s1, l1), REC(i->env, s2, l2))) |
8c912eea TRC |
99 | |
100 | #define TABLE_HASH(index, side, line) \ | |
101 | XDL_HASHLONG((REC(index->env, side, line))->ha, index->table_bits) | |
102 | ||
103 | static int scanA(struct histindex *index, int line1, int count1) | |
104 | { | |
105 | unsigned int ptr, tbl_idx; | |
106 | unsigned int chain_len; | |
107 | struct record **rec_chain, *rec; | |
108 | ||
109 | for (ptr = LINE_END(1); line1 <= ptr; ptr--) { | |
110 | tbl_idx = TABLE_HASH(index, 1, ptr); | |
111 | rec_chain = index->records + tbl_idx; | |
112 | rec = *rec_chain; | |
113 | ||
114 | chain_len = 0; | |
115 | while (rec) { | |
116 | if (CMP(index, 1, rec->ptr, 1, ptr)) { | |
117 | /* | |
118 | * ptr is identical to another element. Insert | |
119 | * it onto the front of the existing element | |
120 | * chain. | |
121 | */ | |
122 | NEXT_PTR(index, ptr) = rec->ptr; | |
123 | rec->ptr = ptr; | |
124 | /* cap rec->cnt at MAX_CNT */ | |
125 | rec->cnt = XDL_MIN(MAX_CNT, rec->cnt + 1); | |
126 | LINE_MAP(index, ptr) = rec; | |
127 | goto continue_scan; | |
128 | } | |
129 | ||
130 | rec = rec->next; | |
131 | chain_len++; | |
132 | } | |
133 | ||
134 | if (chain_len == index->max_chain_length) | |
135 | return -1; | |
136 | ||
137 | /* | |
138 | * This is the first time we have ever seen this particular | |
139 | * element in the sequence. Construct a new chain for it. | |
140 | */ | |
141 | if (!(rec = xdl_cha_alloc(&index->rcha))) | |
142 | return -1; | |
143 | rec->ptr = ptr; | |
144 | rec->cnt = 1; | |
145 | rec->next = *rec_chain; | |
146 | *rec_chain = rec; | |
147 | LINE_MAP(index, ptr) = rec; | |
148 | ||
149 | continue_scan: | |
150 | ; /* no op */ | |
151 | } | |
152 | ||
153 | return 0; | |
154 | } | |
155 | ||
156 | static int try_lcs(struct histindex *index, struct region *lcs, int b_ptr, | |
157 | int line1, int count1, int line2, int count2) | |
158 | { | |
159 | unsigned int b_next = b_ptr + 1; | |
160 | struct record *rec = index->records[TABLE_HASH(index, 2, b_ptr)]; | |
161 | unsigned int as, ae, bs, be, np, rc; | |
162 | int should_break; | |
163 | ||
164 | for (; rec; rec = rec->next) { | |
165 | if (rec->cnt > index->cnt) { | |
166 | if (!index->has_common) | |
167 | index->has_common = CMP(index, 1, rec->ptr, 2, b_ptr); | |
168 | continue; | |
169 | } | |
170 | ||
171 | as = rec->ptr; | |
172 | if (!CMP(index, 1, as, 2, b_ptr)) | |
173 | continue; | |
174 | ||
175 | index->has_common = 1; | |
176 | for (;;) { | |
177 | should_break = 0; | |
178 | np = NEXT_PTR(index, as); | |
179 | bs = b_ptr; | |
180 | ae = as; | |
181 | be = bs; | |
182 | rc = rec->cnt; | |
183 | ||
184 | while (line1 < as && line2 < bs | |
185 | && CMP(index, 1, as - 1, 2, bs - 1)) { | |
186 | as--; | |
187 | bs--; | |
188 | if (1 < rc) | |
189 | rc = XDL_MIN(rc, CNT(index, as)); | |
190 | } | |
191 | while (ae < LINE_END(1) && be < LINE_END(2) | |
192 | && CMP(index, 1, ae + 1, 2, be + 1)) { | |
193 | ae++; | |
194 | be++; | |
195 | if (1 < rc) | |
196 | rc = XDL_MIN(rc, CNT(index, ae)); | |
197 | } | |
198 | ||
199 | if (b_next <= be) | |
200 | b_next = be + 1; | |
201 | if (lcs->end1 - lcs->begin1 < ae - as || rc < index->cnt) { | |
202 | lcs->begin1 = as; | |
203 | lcs->begin2 = bs; | |
204 | lcs->end1 = ae; | |
205 | lcs->end2 = be; | |
206 | index->cnt = rc; | |
207 | } | |
208 | ||
209 | if (np == 0) | |
210 | break; | |
211 | ||
212 | while (np <= ae) { | |
213 | np = NEXT_PTR(index, np); | |
214 | if (np == 0) { | |
215 | should_break = 1; | |
216 | break; | |
217 | } | |
218 | } | |
219 | ||
220 | if (should_break) | |
221 | break; | |
222 | ||
223 | as = np; | |
224 | } | |
225 | } | |
226 | return b_next; | |
227 | } | |
228 | ||
28209850 SB |
229 | static int fall_back_to_classic_diff(xpparam_t const *xpp, xdfenv_t *env, |
230 | int line1, int count1, int line2, int count2) | |
231 | { | |
232 | xpparam_t xpparam; | |
ec7967cf MK |
233 | |
234 | memset(&xpparam, 0, sizeof(xpparam)); | |
28209850 SB |
235 | xpparam.flags = xpp->flags & ~XDF_DIFF_ALGORITHM_MASK; |
236 | ||
237 | return xdl_fall_back_diff(env, &xpparam, | |
238 | line1, count1, line2, count2); | |
239 | } | |
240 | ||
c671d4b5 SB |
241 | static inline void free_index(struct histindex *index) |
242 | { | |
243 | xdl_free(index->records); | |
244 | xdl_free(index->line_map); | |
245 | xdl_free(index->next_ptrs); | |
246 | xdl_cha_free(&index->rcha); | |
247 | } | |
248 | ||
64c4e8bc SB |
249 | static int find_lcs(xpparam_t const *xpp, xdfenv_t *env, |
250 | struct region *lcs, | |
251 | int line1, int count1, int line2, int count2) | |
8c912eea | 252 | { |
64c4e8bc | 253 | int b_ptr; |
18aae7e2 | 254 | int ret = -1; |
8c912eea | 255 | struct histindex index; |
8c912eea TRC |
256 | |
257 | memset(&index, 0, sizeof(index)); | |
258 | ||
259 | index.env = env; | |
260 | index.xpp = xpp; | |
261 | ||
262 | index.records = NULL; | |
263 | index.line_map = NULL; | |
264 | /* in case of early xdl_cha_free() */ | |
265 | index.rcha.head = NULL; | |
266 | ||
267 | index.table_bits = xdl_hashbits(count1); | |
18aae7e2 | 268 | index.records_size = 1 << index.table_bits; |
848fd5ae | 269 | if (!XDL_CALLOC_ARRAY(index.records, index.records_size)) |
8c912eea | 270 | goto cleanup; |
8c912eea | 271 | |
18aae7e2 | 272 | index.line_map_size = count1; |
848fd5ae | 273 | if (!XDL_CALLOC_ARRAY(index.line_map, index.line_map_size)) |
8c912eea | 274 | goto cleanup; |
8c912eea | 275 | |
848fd5ae | 276 | if (!XDL_CALLOC_ARRAY(index.next_ptrs, index.line_map_size)) |
8c912eea | 277 | goto cleanup; |
8c912eea TRC |
278 | |
279 | /* lines / 4 + 1 comes from xprepare.c:xdl_prepare_ctx() */ | |
280 | if (xdl_cha_init(&index.rcha, sizeof(struct record), count1 / 4 + 1) < 0) | |
281 | goto cleanup; | |
282 | ||
283 | index.ptr_shift = line1; | |
284 | index.max_chain_length = 64; | |
285 | ||
64c4e8bc SB |
286 | if (scanA(&index, line1, count1)) |
287 | goto cleanup; | |
288 | ||
289 | index.cnt = index.max_chain_length + 1; | |
290 | ||
291 | for (b_ptr = line2; b_ptr <= LINE_END(2); ) | |
292 | b_ptr = try_lcs(&index, lcs, b_ptr, line1, count1, line2, count2); | |
293 | ||
294 | if (index.has_common && index.max_chain_length < index.cnt) | |
295 | ret = 1; | |
296 | else | |
297 | ret = 0; | |
298 | ||
299 | cleanup: | |
300 | free_index(&index); | |
301 | return ret; | |
302 | } | |
303 | ||
304 | static int histogram_diff(xpparam_t const *xpp, xdfenv_t *env, | |
305 | int line1, int count1, int line2, int count2) | |
306 | { | |
307 | struct region lcs; | |
308 | int lcs_found; | |
79cb2ebb SB |
309 | int result; |
310 | redo: | |
311 | result = -1; | |
64c4e8bc SB |
312 | |
313 | if (count1 <= 0 && count2 <= 0) | |
314 | return 0; | |
315 | ||
316 | if (LINE_END(1) >= MAX_PTR) | |
317 | return -1; | |
318 | ||
319 | if (!count1) { | |
320 | while(count2--) | |
321 | env->xdf2.rchg[line2++ - 1] = 1; | |
322 | return 0; | |
323 | } else if (!count2) { | |
324 | while(count1--) | |
325 | env->xdf1.rchg[line1++ - 1] = 1; | |
326 | return 0; | |
327 | } | |
328 | ||
8c912eea | 329 | memset(&lcs, 0, sizeof(lcs)); |
64c4e8bc SB |
330 | lcs_found = find_lcs(xpp, env, &lcs, line1, count1, line2, count2); |
331 | if (lcs_found < 0) | |
332 | goto out; | |
333 | else if (lcs_found) | |
28209850 | 334 | result = fall_back_to_classic_diff(xpp, env, line1, count1, line2, count2); |
8c912eea | 335 | else { |
8c912eea | 336 | if (lcs.begin1 == 0 && lcs.begin2 == 0) { |
6486a84c TRC |
337 | while (count1--) |
338 | env->xdf1.rchg[line1++ - 1] = 1; | |
339 | while (count2--) | |
340 | env->xdf2.rchg[line2++ - 1] = 1; | |
19f7a9c5 | 341 | result = 0; |
8c912eea TRC |
342 | } else { |
343 | result = histogram_diff(xpp, env, | |
19f7a9c5 TRC |
344 | line1, lcs.begin1 - line1, |
345 | line2, lcs.begin2 - line2); | |
346 | if (result) | |
64c4e8bc | 347 | goto out; |
79cb2ebb SB |
348 | /* |
349 | * result = histogram_diff(xpp, env, | |
350 | * lcs.end1 + 1, LINE_END(1) - lcs.end1, | |
351 | * lcs.end2 + 1, LINE_END(2) - lcs.end2); | |
352 | * but let's optimize tail recursion ourself: | |
353 | */ | |
354 | count1 = LINE_END(1) - lcs.end1; | |
355 | line1 = lcs.end1 + 1; | |
356 | count2 = LINE_END(2) - lcs.end2; | |
357 | line2 = lcs.end2 + 1; | |
358 | goto redo; | |
8c912eea TRC |
359 | } |
360 | } | |
64c4e8bc | 361 | out: |
8c912eea TRC |
362 | return result; |
363 | } | |
364 | ||
f1d01907 | 365 | int xdl_do_histogram_diff(xpparam_t const *xpp, xdfenv_t *env) |
8c912eea | 366 | { |
43ca7530 TRC |
367 | return histogram_diff(xpp, env, |
368 | env->xdf1.dstart + 1, env->xdf1.dend - env->xdf1.dstart + 1, | |
369 | env->xdf2.dstart + 1, env->xdf2.dend - env->xdf2.dstart + 1); | |
8c912eea | 370 | } |