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comparison mercurial/bdiff.c @ 474:b2ae8283d1a6

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Minor speed improvements for bdiff -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Minor speed improvements for bdiff Consolidate the jpos/jlen arrays to improve cache locality. Do the same for the hash head/length arrays. manifest hash: e6d9ed36782741b1d6fcce8c2d00155a9540e81d -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (GNU/Linux) iD8DBQFCvzWxywK+sNU5EO8RAlTMAJ9+yl0dKIeWv4RegeLy7g6wcnoYwgCgk6la ip6KEAyBb7ktsX14KyZ5+/s= =utNJ -----END PGP SIGNATURE-----
author mpm@selenic.com
date Sun, 26 Jun 2005 15:09:37 -0800
parents aa3d592df9b9
children 934279f3ca53
comparison
equal deleted inserted replaced
473:5914e27dc717 474:b2ae8283d1a6
26 #endif 26 #endif
27 27
28 struct line { 28 struct line {
29 int h, len, n, e; 29 int h, len, n, e;
30 const char *l; 30 const char *l;
31 };
32
33 struct pos {
34 int pos, len;
31 }; 35 };
32 36
33 struct hunk { 37 struct hunk {
34 int a1, a2, b1, b2; 38 int a1, a2, b1, b2;
35 }; 39 };
85 return a->h != b->h || a->len != b->len || memcmp(a->l, b->l, a->len); 89 return a->h != b->h || a->len != b->len || memcmp(a->l, b->l, a->len);
86 } 90 }
87 91
88 static int equatelines(struct line *a, int an, struct line *b, int bn) 92 static int equatelines(struct line *a, int an, struct line *b, int bn)
89 { 93 {
90 int i, j, buckets = 1, t, *h, *l; 94 int i, j, buckets = 1, t;
95 struct pos *h;
91 96
92 /* build a hash table of the next highest power of 2 */ 97 /* build a hash table of the next highest power of 2 */
93 while (buckets < bn + 1) 98 while (buckets < bn + 1)
94 buckets *= 2; 99 buckets *= 2;
95 100
96 h = malloc(buckets * sizeof(int)); 101 h = malloc(buckets * sizeof(struct pos));
97 l = calloc(buckets, sizeof(int));
98 buckets = buckets - 1; 102 buckets = buckets - 1;
99 if (!h || !l) { 103 if (!h)
100 free(h);
101 return 0; 104 return 0;
102 }
103 105
104 /* clear the hash table */ 106 /* clear the hash table */
105 for (i = 0; i <= buckets; i++) 107 for (i = 0; i <= buckets; i++) {
106 h[i] = -1; 108 h[i].pos = -1;
109 h[i].len = 0;
110 }
107 111
108 /* add lines to the hash table chains */ 112 /* add lines to the hash table chains */
109 for (i = bn - 1; i >= 0; i--) { 113 for (i = bn - 1; i >= 0; i--) {
110 /* find the equivalence class */ 114 /* find the equivalence class */
111 for (j = b[i].h & buckets; h[j] != -1; j = (j + 1) & buckets) 115 for (j = b[i].h & buckets; h[j].pos != -1;
112 if (!cmp(b + i, b + h[j])) 116 j = (j + 1) & buckets)
117 if (!cmp(b + i, b + h[j].pos))
113 break; 118 break;
114 119
115 /* add to the head of the equivalence class */ 120 /* add to the head of the equivalence class */
116 b[i].n = h[j]; 121 b[i].n = h[j].pos;
117 b[i].e = j; 122 b[i].e = j;
118 h[j] = i; 123 h[j].pos = i;
119 l[j]++; /* keep track of popularity */ 124 h[j].len++; /* keep track of popularity */
120 } 125 }
121 126
122 /* compute popularity threshold */ 127 /* compute popularity threshold */
123 t = (bn >= 200) ? bn / 100 : bn + 1; 128 t = (bn >= 200) ? bn / 100 : bn + 1;
124 129
125 /* match items in a to their equivalence class in b */ 130 /* match items in a to their equivalence class in b */
126 for (i = 0; i < an; i++) { 131 for (i = 0; i < an; i++) {
127 /* find the equivalence class */ 132 /* find the equivalence class */
128 for (j = a[i].h & buckets; h[j] != -1; j = (j + 1) & buckets) 133 for (j = a[i].h & buckets; h[j].pos != -1;
129 if (!cmp(a + i, b + h[j])) 134 j = (j + 1) & buckets)
135 if (!cmp(a + i, b + h[j].pos))
130 break; 136 break;
131 137
132 a[i].e = j; /* use equivalence class for quick compare */ 138 a[i].e = j; /* use equivalence class for quick compare */
133 if(l[j] <= t) 139 if(h[j].len <= t)
134 a[i].n = h[j]; /* point to head of match list */ 140 a[i].n = h[j].pos; /* point to head of match list */
135 else 141 else
136 a[i].n = -1; /* too popular */ 142 a[i].n = -1; /* too popular */
137 } 143 }
138 144
139 /* discard hash tables */ 145 /* discard hash tables */
140 free(h); 146 free(h);
141 free(l);
142 return 1; 147 return 1;
143 } 148 }
144 149
145 static int longest_match(struct line *a, struct line *b, int *jpos, int *jlen, 150 static int longest_match(struct line *a, struct line *b, struct pos *pos,
146 int a1, int a2, int b1, int b2, int *omi, int *omj) 151 int a1, int a2, int b1, int b2, int *omi, int *omj)
147 { 152 {
148 int mi = a1, mj = b1, mk = 0, mb = 0, i, j, k; 153 int mi = a1, mj = b1, mk = 0, mb = 0, i, j, k;
149 154
150 for (i = a1; i < a2; i++) { 155 for (i = a1; i < a2; i++) {
153 ; 158 ;
154 159
155 /* loop through all lines match a[i] in b */ 160 /* loop through all lines match a[i] in b */
156 for (; j != -1 && j < b2; j = b[j].n) { 161 for (; j != -1 && j < b2; j = b[j].n) {
157 /* does this extend an earlier match? */ 162 /* does this extend an earlier match? */
158 if (i > a1 && j > b1 && jpos[j - 1] == i - 1) 163 if (i > a1 && j > b1 && pos[j - 1].pos == i - 1)
159 k = jlen[j - 1] + 1; 164 k = pos[j - 1].len + 1;
160 else 165 else
161 k = 1; 166 k = 1;
162 jpos[j] = i; 167 pos[j].pos = i;
163 jlen[j] = k; 168 pos[j].len = k;
164 169
165 /* best match so far? */ 170 /* best match so far? */
166 if (k > mk) { 171 if (k > mk) {
167 mi = i; 172 mi = i;
168 mj = j; 173 mj = j;
187 *omi = mi - mb; 192 *omi = mi - mb;
188 *omj = mj - mb; 193 *omj = mj - mb;
189 return mk + mb; 194 return mk + mb;
190 } 195 }
191 196
192 static void recurse(struct line *a, struct line *b, int *jpos, int *jlen, 197 static void recurse(struct line *a, struct line *b, struct pos *pos,
193 int a1, int a2, int b1, int b2, struct hunklist *l) 198 int a1, int a2, int b1, int b2, struct hunklist *l)
194 { 199 {
195 int i, j, k; 200 int i, j, k;
196 201
197 /* find the longest match in this chunk */ 202 /* find the longest match in this chunk */
198 k = longest_match(a, b, jpos, jlen, a1, a2, b1, b2, &i, &j); 203 k = longest_match(a, b, pos, a1, a2, b1, b2, &i, &j);
199 if (!k) 204 if (!k)
200 return; 205 return;
201 206
202 /* and recurse on the remaining chunks on either side */ 207 /* and recurse on the remaining chunks on either side */
203 recurse(a, b, jpos, jlen, a1, i, b1, j, l); 208 recurse(a, b, pos, a1, i, b1, j, l);
204 l->head->a1 = i; 209 l->head->a1 = i;
205 l->head->a2 = i + k; 210 l->head->a2 = i + k;
206 l->head->b1 = j; 211 l->head->b1 = j;
207 l->head->b2 = j + k; 212 l->head->b2 = j + k;
208 l->head++; 213 l->head++;
209 recurse(a, b, jpos, jlen, i + k, a2, j + k, b2, l); 214 recurse(a, b, pos, i + k, a2, j + k, b2, l);
210 } 215 }
211 216
212 static struct hunklist diff(struct line *a, int an, struct line *b, int bn) 217 static struct hunklist diff(struct line *a, int an, struct line *b, int bn)
213 { 218 {
214 struct hunklist l; 219 struct hunklist l;
215 int *jpos, *jlen, t; 220 struct pos *pos;
221 int t;
216 222
217 /* allocate and fill arrays */ 223 /* allocate and fill arrays */
218 t = equatelines(a, an, b, bn); 224 t = equatelines(a, an, b, bn);
219 jpos = calloc(bn, sizeof(int)); 225 pos = calloc(bn, sizeof(struct pos));
220 jlen = calloc(bn, sizeof(int));
221 l.head = l.base = malloc(sizeof(struct hunk) * ((an + bn) / 4 + 2)); 226 l.head = l.base = malloc(sizeof(struct hunk) * ((an + bn) / 4 + 2));
222 227
223 if (jpos && jlen && l.base && t) { 228 if (pos && l.base && t) {
224 /* generate the matching block list */ 229 /* generate the matching block list */
225 recurse(a, b, jpos, jlen, 0, an, 0, bn, &l); 230 recurse(a, b, pos, 0, an, 0, bn, &l);
226 l.head->a1 = an; 231 l.head->a1 = an;
227 l.head->b1 = bn; 232 l.head->b1 = bn;
228 l.head++; 233 l.head++;
229 } 234 }
230 235
231 free(jpos); 236 free(pos);
232 free(jlen);
233 return l; 237 return l;
234 } 238 }
235 239
236 static PyObject *blocks(PyObject *self, PyObject *args) 240 static PyObject *blocks(PyObject *self, PyObject *args)
237 { 241 {