Code

Merge branch 'jk/maint-mv'
[git.git] / xdiff / xhistogram.c
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  */
44 #include "xinclude.h"
45 #include "xtypes.h"
46 #include "xdiff.h"
48 #define MAX_PTR UINT_MAX
49 #define MAX_CNT UINT_MAX
51 #define LINE_END(n) (line##n + count##n - 1)
52 #define LINE_END_PTR(n) (*line##n + *count##n - 1)
54 struct histindex {
55         struct record {
56                 unsigned int ptr, cnt;
57                 struct record *next;
58         } **records, /* an ocurrence */
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;
66         unsigned int max_chain_length,
67                      key_shift,
68                      ptr_shift;
70         unsigned int cnt,
71                      has_common;
73         xdfenv_t *env;
74         xpparam_t const *xpp;
75 };
77 struct region {
78         unsigned int begin1, end1;
79         unsigned int begin2, end2;
80 };
82 #define LINE_MAP(i, a) (i->line_map[(a) - i->ptr_shift])
84 #define NEXT_PTR(index, ptr) \
85         (index->next_ptrs[(ptr) - index->ptr_shift])
87 #define CNT(index, ptr) \
88         ((LINE_MAP(index, ptr))->cnt)
90 #define REC(env, s, l) \
91         (env->xdf##s.recs[l - 1])
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 }
101 #define CMP_ENV(xpp, env, s1, l1, s2, l2) \
102         (cmp_recs(xpp, REC(env, s1, l1), REC(env, s2, l2)))
104 #define CMP(i, s1, l1, s2, l2) \
105         (cmp_recs(i->xpp, REC(i->env, s1, l1), REC(i->env, s2, l2)))
107 #define TABLE_HASH(index, side, line) \
108         XDL_HASHLONG((REC(index->env, side, line))->ha, index->table_bits)
110 static int scanA(struct histindex *index, int line1, int count1)
112         unsigned int ptr, tbl_idx;
113         unsigned int chain_len;
114         struct record **rec_chain, *rec;
116         for (ptr = LINE_END(1); line1 <= ptr; ptr--) {
117                 tbl_idx = TABLE_HASH(index, 1, ptr);
118                 rec_chain = index->records + tbl_idx;
119                 rec = *rec_chain;
121                 chain_len = 0;
122                 while (rec) {
123                         if (CMP(index, 1, rec->ptr, 1, ptr)) {
124                                 /*
125                                  * ptr is identical to another element. Insert
126                                  * it onto the front of the existing element
127                                  * chain.
128                                  */
129                                 NEXT_PTR(index, ptr) = rec->ptr;
130                                 rec->ptr = ptr;
131                                 /* cap rec->cnt at MAX_CNT */
132                                 rec->cnt = XDL_MIN(MAX_CNT, rec->cnt + 1);
133                                 LINE_MAP(index, ptr) = rec;
134                                 goto continue_scan;
135                         }
137                         rec = rec->next;
138                         chain_len++;
139                 }
141                 if (chain_len == index->max_chain_length)
142                         return -1;
144                 /*
145                  * This is the first time we have ever seen this particular
146                  * element in the sequence. Construct a new chain for it.
147                  */
148                 if (!(rec = xdl_cha_alloc(&index->rcha)))
149                         return -1;
150                 rec->ptr = ptr;
151                 rec->cnt = 1;
152                 rec->next = *rec_chain;
153                 *rec_chain = rec;
154                 LINE_MAP(index, ptr) = rec;
156 continue_scan:
157                 ; /* no op */
158         }
160         return 0;
163 static int try_lcs(struct histindex *index, struct region *lcs, int b_ptr,
164         int line1, int count1, int line2, int count2)
166         unsigned int b_next = b_ptr + 1;
167         struct record *rec = index->records[TABLE_HASH(index, 2, b_ptr)];
168         unsigned int as, ae, bs, be, np, rc;
169         int should_break;
171         for (; rec; rec = rec->next) {
172                 if (rec->cnt > index->cnt) {
173                         if (!index->has_common)
174                                 index->has_common = CMP(index, 1, rec->ptr, 2, b_ptr);
175                         continue;
176                 }
178                 as = rec->ptr;
179                 if (!CMP(index, 1, as, 2, b_ptr))
180                         continue;
182                 index->has_common = 1;
183                 for (;;) {
184                         should_break = 0;
185                         np = NEXT_PTR(index, as);
186                         bs = b_ptr;
187                         ae = as;
188                         be = bs;
189                         rc = rec->cnt;
191                         while (line1 < as && line2 < bs
192                                 && CMP(index, 1, as - 1, 2, bs - 1)) {
193                                 as--;
194                                 bs--;
195                                 if (1 < rc)
196                                         rc = XDL_MIN(rc, CNT(index, as));
197                         }
198                         while (ae < LINE_END(1) && be < LINE_END(2)
199                                 && CMP(index, 1, ae + 1, 2, be + 1)) {
200                                 ae++;
201                                 be++;
202                                 if (1 < rc)
203                                         rc = XDL_MIN(rc, CNT(index, ae));
204                         }
206                         if (b_next <= be)
207                                 b_next = be + 1;
208                         if (lcs->end1 - lcs->begin1 < ae - as || rc < index->cnt) {
209                                 lcs->begin1 = as;
210                                 lcs->begin2 = bs;
211                                 lcs->end1 = ae;
212                                 lcs->end2 = be;
213                                 index->cnt = rc;
214                         }
216                         if (np == 0)
217                                 break;
219                         while (np <= ae) {
220                                 np = NEXT_PTR(index, np);
221                                 if (np == 0) {
222                                         should_break = 1;
223                                         break;
224                                 }
225                         }
227                         if (should_break)
228                                 break;
230                         as = np;
231                 }
232         }
233         return b_next;
236 static int find_lcs(struct histindex *index, struct region *lcs,
237         int line1, int count1, int line2, int count2) {
238         int b_ptr;
240         if (scanA(index, line1, count1))
241                 return -1;
243         index->cnt = index->max_chain_length + 1;
245         for (b_ptr = line2; b_ptr <= LINE_END(2); )
246                 b_ptr = try_lcs(index, lcs, b_ptr, line1, count1, line2, count2);
248         return index->has_common && index->max_chain_length < index->cnt;
251 static int fall_back_to_classic_diff(struct histindex *index,
252                 int line1, int count1, int line2, int count2)
254         xpparam_t xpp;
255         xpp.flags = index->xpp->flags & ~XDF_HISTOGRAM_DIFF;
257         return xdl_fall_back_diff(index->env, &xpp,
258                                   line1, count1, line2, count2);
261 static int histogram_diff(xpparam_t const *xpp, xdfenv_t *env,
262         int line1, int count1, int line2, int count2)
264         struct histindex index;
265         struct region lcs;
266         int sz;
267         int result = -1;
269         if (count1 <= 0 && count2 <= 0)
270                 return 0;
272         if (LINE_END(1) >= MAX_PTR)
273                 return -1;
275         if (!count1) {
276                 while(count2--)
277                         env->xdf2.rchg[line2++ - 1] = 1;
278                 return 0;
279         } else if (!count2) {
280                 while(count1--)
281                         env->xdf1.rchg[line1++ - 1] = 1;
282                 return 0;
283         }
285         memset(&index, 0, sizeof(index));
287         index.env = env;
288         index.xpp = xpp;
290         index.records = NULL;
291         index.line_map = NULL;
292         /* in case of early xdl_cha_free() */
293         index.rcha.head = NULL;
295         index.table_bits = xdl_hashbits(count1);
296         sz = index.records_size = 1 << index.table_bits;
297         sz *= sizeof(struct record *);
298         if (!(index.records = (struct record **) xdl_malloc(sz)))
299                 goto cleanup;
300         memset(index.records, 0, sz);
302         sz = index.line_map_size = count1;
303         sz *= sizeof(struct record *);
304         if (!(index.line_map = (struct record **) xdl_malloc(sz)))
305                 goto cleanup;
306         memset(index.line_map, 0, sz);
308         sz = index.line_map_size;
309         sz *= sizeof(unsigned int);
310         if (!(index.next_ptrs = (unsigned int *) xdl_malloc(sz)))
311                 goto cleanup;
312         memset(index.next_ptrs, 0, sz);
314         /* lines / 4 + 1 comes from xprepare.c:xdl_prepare_ctx() */
315         if (xdl_cha_init(&index.rcha, sizeof(struct record), count1 / 4 + 1) < 0)
316                 goto cleanup;
318         index.ptr_shift = line1;
319         index.max_chain_length = 64;
321         memset(&lcs, 0, sizeof(lcs));
322         if (find_lcs(&index, &lcs, line1, count1, line2, count2))
323                 result = fall_back_to_classic_diff(&index, line1, count1, line2, count2);
324         else {
325                 if (lcs.begin1 == 0 && lcs.begin2 == 0) {
326                         while (count1--)
327                                 env->xdf1.rchg[line1++ - 1] = 1;
328                         while (count2--)
329                                 env->xdf2.rchg[line2++ - 1] = 1;
330                         result = 0;
331                 } else {
332                         result = histogram_diff(xpp, env,
333                                                 line1, lcs.begin1 - line1,
334                                                 line2, lcs.begin2 - line2);
335                         if (result)
336                                 goto cleanup;
337                         result = histogram_diff(xpp, env,
338                                                 lcs.end1 + 1, LINE_END(1) - lcs.end1,
339                                                 lcs.end2 + 1, LINE_END(2) - lcs.end2);
340                         if (result)
341                                 goto cleanup;
342                 }
343         }
345 cleanup:
346         xdl_free(index.records);
347         xdl_free(index.line_map);
348         xdl_free(index.next_ptrs);
349         xdl_cha_free(&index.rcha);
351         return result;
354 int xdl_do_histogram_diff(mmfile_t *file1, mmfile_t *file2,
355         xpparam_t const *xpp, xdfenv_t *env)
357         if (xdl_prepare_env(file1, file2, xpp, env) < 0)
358                 return -1;
360         return histogram_diff(xpp, env,
361                 env->xdf1.dstart + 1, env->xdf1.dend - env->xdf1.dstart + 1,
362                 env->xdf2.dstart + 1, env->xdf2.dend - env->xdf2.dstart + 1);