1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
|
/**************************************************************************
*
* Copyright 2008 VMware, Inc.
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sub license, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice (including the
* next paragraph) shall be included in all copies or substantial portions
* of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
* IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
* ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
**************************************************************************/
/**
* @file
* Simple cache implementation.
*
* We simply have fixed size array, and destroy previous values on collision.
*
* @author Jose Fonseca <jfonseca@vmware.com>
*/
#include "pipe/p_compiler.h"
#include "util/u_debug.h"
#include "util/u_math.h"
#include "util/u_memory.h"
#include "util/u_cache.h"
struct util_cache_entry
{
void *key;
void *value;
#ifdef DEBUG
unsigned count;
#endif
};
struct util_cache
{
/** Hash function */
uint32_t (*hash)(const void *key);
/** Compare two keys */
int (*compare)(const void *key1, const void *key2);
/** Destroy a (key, value) pair */
void (*destroy)(void *key, void *value);
uint32_t size;
struct util_cache_entry *entries;
#ifdef DEBUG
unsigned count;
#endif
};
struct util_cache *
util_cache_create(uint32_t (*hash)(const void *key),
int (*compare)(const void *key1, const void *key2),
void (*destroy)(void *key, void *value),
uint32_t size)
{
struct util_cache *cache;
cache = CALLOC_STRUCT(util_cache);
if(!cache)
return NULL;
cache->hash = hash;
cache->compare = compare;
cache->destroy = destroy;
cache->size = size;
cache->entries = CALLOC(size, sizeof(struct util_cache_entry));
if(!cache->entries) {
FREE(cache);
return NULL;
}
return cache;
}
static INLINE struct util_cache_entry *
util_cache_entry_get(struct util_cache *cache,
const void *key)
{
uint32_t hash;
hash = cache->hash(key);
return &cache->entries[hash % cache->size];
}
static INLINE void
util_cache_entry_destroy(struct util_cache *cache,
struct util_cache_entry *entry)
{
void *key = entry->key;
void *value = entry->value;
entry->key = NULL;
entry->value = NULL;
if(key || value)
if(cache->destroy)
cache->destroy(key, value);
}
void
util_cache_set(struct util_cache *cache,
void *key,
void *value)
{
struct util_cache_entry *entry;
assert(cache);
if (!cache)
return;
entry = util_cache_entry_get(cache, key);
util_cache_entry_destroy(cache, entry);
#ifdef DEBUG
++entry->count;
++cache->count;
#endif
entry->key = key;
entry->value = value;
}
void *
util_cache_get(struct util_cache *cache,
const void *key)
{
struct util_cache_entry *entry;
assert(cache);
if (!cache)
return NULL;
entry = util_cache_entry_get(cache, key);
if(!entry->key && !entry->value)
return NULL;
if(cache->compare(key, entry->key) != 0)
return NULL;
return entry->value;
}
void
util_cache_clear(struct util_cache *cache)
{
uint32_t i;
assert(cache);
if (!cache)
return;
for(i = 0; i < cache->size; ++i)
util_cache_entry_destroy(cache, &cache->entries[i]);
}
void
util_cache_destroy(struct util_cache *cache)
{
assert(cache);
if (!cache)
return;
#ifdef DEBUG
if(cache->count >= 20*cache->size) {
/* Normal approximation of the Poisson distribution */
double mean = (double)cache->count/(double)cache->size;
double stddev = sqrt(mean);
unsigned i;
for(i = 0; i < cache->size; ++i) {
double z = fabs(cache->count - mean)/stddev;
/* This assert should not fail 99.9999998027% of the times, unless
* the hash function is a poor one */
assert(z <= 6.0);
}
}
#endif
util_cache_clear(cache);
FREE(cache->entries);
FREE(cache);
}
|
