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 /**
  44  * Create a new cache object.
  45  *
  46  * This function creates the handle necessary for all subsequent cache_*
  47  * functions.
  48  *
  49  * This cache provides two distinct operations:
  50  *
  51  *   o Storage and retrieval of arbitrary objects by cryptographic
  52  *     name (or "key").  This is provided via disk_cache_put() and
  53  *     disk_cache_get().
  54  *
  55  *   o The ability to store a key alone and check later whether the
  56  *     key was previously stored. This is provided via disk_cache_put_key()
  57  *     and disk_cache_has_key().
  58  *
  59  * The put_key()/has_key() operations are conceptually identical to
  60  * put()/get() with no data, but are provided separately to allow for
  61  * a more efficient implementation.
  62  *
  63  * In all cases, the keys are sequences of 20 bytes. It is anticipated
  64  * that callers will compute appropriate SHA-1 signatures for keys,
  65  * (though nothing in this implementation directly relies on how the
  66  * names are computed). See mesa-sha1.h and _mesa_sha1_compute for
  67  * assistance in computing SHA-1 signatures.
  68  */
  69 struct disk_cache *
  70 disk_cache_create(void);
  71
  72 /**
  73  * Destroy a cache object, (freeing all associated resources).
  74  */
  75 void
  76 disk_cache_destroy(struct disk_cache *cache);
  77
  78 /**
  79  * Store an item in the cache under the name \key.
  80  *
  81  * The item can be retrieved later with disk_cache_get(), (unless the item has
  82  * been evicted in the interim).
  83  *
  84  * Any call to disk_cache_put() may cause an existing, random item to be
  85  * evicted from the cache.
  86  */
  87 void
  88 disk_cache_put(struct disk_cache *cache, cache_key key,
  89                const void *data, size_t size);
  90
  91 /**
  92  * Retrieve an item previously stored in the cache with the name <key>.
  93  *
  94  * The item must have been previously stored with a call to disk_cache_put().
  95  *
  96  * If \size is non-NULL, then, on successful return, it will be set to the
  97  * size of the object.
  98  *
  99  * \return A pointer to the stored object if found. NULL if the object
 100  * is not found, or if any error occurs, (memory allocation failure,
 101  * filesystem error, etc.). The returned data is malloc'ed so the
 102  * caller should call free() it when finished.
 103  */
 104 void *
 105 disk_cache_get(struct disk_cache *cache, cache_key key, size_t *size);
 106
 107 /**
 108  * Store the name \key within the cache, (without any associated data).
 109  *
 110  * Later this key can be checked with disk_cache_has_key(), (unless the key
 111  * has been evicted in the interim).
 112  *
 113  * Any call to cache_record() may cause an existing, random key to be
 114  * evicted from the cache.
 115  */
 116 void
 117 disk_cache_put_key(struct disk_cache *cache, cache_key key);
 118
 119 /**
 120  * Test whether the name \key was previously recorded in the cache.
 121  *
 122  * Return value: True if disk_cache_put_key() was previously called with
 123  * \key, (and the key was not evicted in the interim).
 124  *
 125  * Note: disk_cache_has_key() will only return true for keys passed to
 126  * disk_cache_put_key(). Specifically, a call to disk_cache_put() will not cause
 127  * disk_cache_has_key() to return true for the same key.
 128  */
 129 bool
 130 disk_cache_has_key(struct disk_cache *cache, cache_key key);
 131
 132 #ifdef __cplusplus
 133 }
 134 #endif
 135
 136 #endif /* CACHE_H */