7e9cb809b597738b7a5d07e25768589371e9c59c
[mesa.git] / src / util / disk_cache.h
1 /*
2 * Copyright © 2014 Intel Corporation
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21 * IN THE SOFTWARE.
22 */
23
24 #ifndef DISK_CACHE_H
25 #define DISK_CACHE_H
26
27 #include <stdint.h>
28 #include <stdbool.h>
29
30 #ifdef __cplusplus
31 extern "C" {
32 #endif
33
34 /* Size of cache keys in bytes. */
35 #define CACHE_KEY_SIZE 20
36
37 typedef uint8_t cache_key[CACHE_KEY_SIZE];
38
39 struct disk_cache;
40
41 /* Provide inlined stub functions if the shader cache is disabled. */
42
43 #ifdef ENABLE_SHADER_CACHE
44
45 /**
46 * Create a new cache object.
47 *
48 * This function creates the handle necessary for all subsequent cache_*
49 * functions.
50 *
51 * This cache provides two distinct operations:
52 *
53 * o Storage and retrieval of arbitrary objects by cryptographic
54 * name (or "key"). This is provided via disk_cache_put() and
55 * disk_cache_get().
56 *
57 * o The ability to store a key alone and check later whether the
58 * key was previously stored. This is provided via disk_cache_put_key()
59 * and disk_cache_has_key().
60 *
61 * The put_key()/has_key() operations are conceptually identical to
62 * put()/get() with no data, but are provided separately to allow for
63 * a more efficient implementation.
64 *
65 * In all cases, the keys are sequences of 20 bytes. It is anticipated
66 * that callers will compute appropriate SHA-1 signatures for keys,
67 * (though nothing in this implementation directly relies on how the
68 * names are computed). See mesa-sha1.h and _mesa_sha1_compute for
69 * assistance in computing SHA-1 signatures.
70 */
71 struct disk_cache *
72 disk_cache_create(void);
73
74 /**
75 * Destroy a cache object, (freeing all associated resources).
76 */
77 void
78 disk_cache_destroy(struct disk_cache *cache);
79
80 /**
81 * Store an item in the cache under the name \key.
82 *
83 * The item can be retrieved later with disk_cache_get(), (unless the item has
84 * been evicted in the interim).
85 *
86 * Any call to disk_cache_put() may cause an existing, random item to be
87 * evicted from the cache.
88 */
89 void
90 disk_cache_put(struct disk_cache *cache, cache_key key,
91 const void *data, size_t size);
92
93 /**
94 * Retrieve an item previously stored in the cache with the name <key>.
95 *
96 * The item must have been previously stored with a call to disk_cache_put().
97 *
98 * If \size is non-NULL, then, on successful return, it will be set to the
99 * size of the object.
100 *
101 * \return A pointer to the stored object if found. NULL if the object
102 * is not found, or if any error occurs, (memory allocation failure,
103 * filesystem error, etc.). The returned data is malloc'ed so the
104 * caller should call free() it when finished.
105 */
106 void *
107 disk_cache_get(struct disk_cache *cache, cache_key key, size_t *size);
108
109 /**
110 * Store the name \key within the cache, (without any associated data).
111 *
112 * Later this key can be checked with disk_cache_has_key(), (unless the key
113 * has been evicted in the interim).
114 *
115 * Any call to cache_record() may cause an existing, random key to be
116 * evicted from the cache.
117 */
118 void
119 disk_cache_put_key(struct disk_cache *cache, cache_key key);
120
121 /**
122 * Test whether the name \key was previously recorded in the cache.
123 *
124 * Return value: True if disk_cache_put_key() was previously called with
125 * \key, (and the key was not evicted in the interim).
126 *
127 * Note: disk_cache_has_key() will only return true for keys passed to
128 * disk_cache_put_key(). Specifically, a call to disk_cache_put() will not cause
129 * disk_cache_has_key() to return true for the same key.
130 */
131 bool
132 disk_cache_has_key(struct disk_cache *cache, cache_key key);
133
134 #else
135
136 static inline struct disk_cache *
137 disk_cache_create(void)
138 {
139 return NULL;
140 }
141
142 static inline void
143 disk_cache_destroy(struct disk_cache *cache) {
144 return;
145 }
146
147 static inline void
148 disk_cache_put(struct disk_cache *cache, cache_key key,
149 const void *data, size_t size)
150 {
151 return;
152 }
153
154 static inline uint8_t *
155 disk_cache_get(struct disk_cache *cache, cache_key key, size_t *size)
156 {
157 return NULL;
158 }
159
160 static inline void
161 disk_cache_put_key(struct disk_cache *cache, cache_key key)
162 {
163 return;
164 }
165
166 static inline bool
167 disk_cache_has_key(struct disk_cache *cache, cache_key key)
168 {
169 return false;
170 }
171
172 #endif /* ENABLE_SHADER_CACHE */
173
174 #ifdef __cplusplus
175 }
176 #endif
177
178 #endif /* CACHE_H */