diff --git a/cache.h b/cache.h index f720ee07e3..1269503653 100644 --- a/cache.h +++ b/cache.h @@ -18,27 +18,99 @@ extern int cache_error; #endif -typedef int cache_constructor_t(void *, void *, int); -typedef void cache_destructor_t(void *, void *); +/** + * Constructor used to initialize allocated objects + * + * @param obj pointer to the object to initialized. + * @param notused1 This parameter is currently not used. + * @param notused2 This parameter is currently not used. + * @return you should return 0, but currently this is not checked + */ +typedef int cache_constructor_t(void* obj, void* notused1, int notused2); +/** + * Destructor used to clean up allocated objects before they are + * returned to the operating system. + * + * @param obj pointer to the object to initialized. + * @param notused1 This parameter is currently not used. + * @param notused2 This parameter is currently not used. + * @return you should return 0, but currently this is not checked + */ +typedef void cache_destructor_t(void* obj, void* notused); +/** + * Definition of the structure to keep track of the internal details of + * the cache allocator. Touching any of these variables results in + * undefined behavior. + */ typedef struct { + /** Mutex to protect access to the structure */ pthread_mutex_t mutex; + /** Name of the cache objects in this cache (provided by the caller) */ char *name; + /** List of pointers to available buffers in this cache */ void **ptr; + /** The size of each element in this cache */ size_t bufsize; + /** The capacity of the list of elements */ int freetotal; + /** The current number of free elements */ int freecurr; + /** The constructor to be called each time we allocate more memory */ cache_constructor_t* constructor; + /** The destructor to be called each time before we release memory */ cache_destructor_t* destructor; } cache_t; - -cache_t* cache_create(const char *name, size_t bufsize, size_t align, +/** + * Create an object cache. + * + * The object cache will let you allocate objects of the same size. It is fully + * MT safe, so you may allocate objects from multiple threads without having to + * do any syncrhonization in the application code. + * + * @param name the name of the object cache. This name may be used for debug purposes + * and may help you track down what kind of object you have problems with + * (buffer overruns, leakage etc) + * @param bufsize the size of each object in the cache + * @param align the alignment requirements of the objects in the cache. + * @param constructor the function to be called to initialize memory when we need + * to allocate more memory from the os. + * @param destructor the function to be called before we release the memory back + * to the os. + * @return a handle to an object cache if successful, NULL otherwise. + */ +cache_t* cache_create(const char* name, size_t bufsize, size_t align, cache_constructor_t* constructor, cache_destructor_t* destructor); -void cache_destroy(cache_t*); -void* cache_alloc(cache_t*); -void cache_free(cache_t*, void*); +/** + * Destroy an object cache. + * + * Destroy and invalidate an object cache. You should return all buffers allocated + * with cache_alloc by using cache_free before calling this function. Not doing + * so results in undefined behavior (the buffers may or may not be invalidated) + * + * @param handle the handle to the object cache to destroy. + */ +void cache_destroy(cache_t* handle); +/** + * Allocate an object from the cache. + * + * @param handle the handle to the object cache to allocate from + * @return a pointer to an initialized object from the cache, or NULL if + * the allocation cannot be satisfied. + */ +void* cache_alloc(cache_t* handle); +/** + * Return an object back to the cache. + * + * The caller should return the object in an initialized state so that + * the object may be returned in an expected state from cache_alloc. + * + * @param handle handle to the object cache to return the object to + * @param ptr pointer to the object to return. + */ +void cache_free(cache_t* handle, void* ptr); #endif #endif