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| -rw-r--r-- | include/iprt/memcache.h | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/include/iprt/memcache.h b/include/iprt/memcache.h new file mode 100644 index 00000000..f594c86e --- /dev/null +++ b/include/iprt/memcache.h @@ -0,0 +1,160 @@ +/** @file + * IPRT - Memory Object Allocation Cache. + */ + +/* + * Copyright (C) 2006-2019 Oracle Corporation + * + * This file is part of VirtualBox Open Source Edition (OSE), as + * available from http://www.virtualbox.org. This file is free software; + * you can redistribute it and/or modify it under the terms of the GNU + * General Public License (GPL) as published by the Free Software + * Foundation, in version 2 as it comes in the "COPYING" file of the + * VirtualBox OSE distribution. VirtualBox OSE is distributed in the + * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind. + * + * The contents of this file may alternatively be used under the terms + * of the Common Development and Distribution License Version 1.0 + * (CDDL) only, as it comes in the "COPYING.CDDL" file of the + * VirtualBox OSE distribution, in which case the provisions of the + * CDDL are applicable instead of those of the GPL. + * + * You may elect to license modified versions of this file under the + * terms and conditions of either the GPL or the CDDL or both. + */ + +#ifndef IPRT_INCLUDED_memcache_h +#define IPRT_INCLUDED_memcache_h +#ifndef RT_WITHOUT_PRAGMA_ONCE +# pragma once +#endif + + +#include <iprt/cdefs.h> +#include <iprt/types.h> + +RT_C_DECLS_BEGIN + + +/** @defgroup grp_rt_memcache RTMemCache - Memory Object Allocation Cache + * @ingroup grp_rt + * + * Optimized allocation, initialization, freeing and destruction of memory + * objects of the same kind and size. Objects are constructed once, then + * allocated and freed one or more times, until finally destructed together with + * the cache (RTMemCacheDestroy). It's expected behavior, even when pfnCtor is + * NULL, that the user will be store information that should be persistent + * across RTMemCacheFree calls. + * + * The objects are zeroed prior to calling pfnCtor. For obvious reasons, the + * objects are not touched by the cache after that, so that RTMemCacheAlloc will + * return the object in the same state as when it as handed to RTMemCacheFree. + * + * @todo A callback for the reuse (at alloc time) might be of interest. + * + * @{ + */ + +/** A memory cache handle. */ +typedef R3R0PTRTYPE(struct RTMEMCACHEINT *) RTMEMCACHE; +/** Pointer to a memory cache handle. */ +typedef RTMEMCACHE *PRTMEMCACHE; +/** Nil memory cache handle. */ +#define NIL_RTMEMCACHE ((RTMEMCACHE)0) + + +/** + * Object constructor. + * + * This is called for when an element is allocated for the first time. + * + * @returns IPRT status code. + * @param hMemCache The cache handle. + * @param pvObj The memory object that should be initialized. + * @param pvUser The user argument. + * + * @remarks No serialization is performed. + */ +typedef DECLCALLBACK(int) FNMEMCACHECTOR(RTMEMCACHE hMemCache, void *pvObj, void *pvUser); +/** Pointer to an object constructor for the memory cache. */ +typedef FNMEMCACHECTOR *PFNMEMCACHECTOR; + +/** + * Object destructor. + * + * This is called when we're shrinking or destroying the cache. + * + * @param hMemCache The cache handle. + * @param pvObj The memory object that should be initialized. + * @param pvUser The user argument. + * + * @remarks No serialization is performed. + */ +typedef DECLCALLBACK(void) FNMEMCACHEDTOR(RTMEMCACHE hMemCache, void *pvObj, void *pvUser); +/** Pointer to an object destructor for the memory cache. */ +typedef FNMEMCACHEDTOR *PFNMEMCACHEDTOR; + + +/** + * Create an allocation cache for fixed size memory objects. + * + * @returns IPRT status code. + * @param phMemCache Where to return the cache handle. + * @param cbObject The size of one memory object. + * @param cbAlignment The object alignment. This must be a power of + * two. The higest alignment is 64. If set to 0, + * a sensible alignment value will be derived from + * the object size. + * @param cMaxObjects The maximum cache size. Pass UINT32_MAX if unsure. + * @param pfnCtor Object constructor callback. Optional. + * @param pfnDtor Object destructor callback. Optional. + * @param pvUser User argument for the two callbacks. + * @param fFlags Flags reserved for future use. Must be zero. + */ +RTDECL(int) RTMemCacheCreate(PRTMEMCACHE phMemCache, size_t cbObject, size_t cbAlignment, uint32_t cMaxObjects, + PFNMEMCACHECTOR pfnCtor, PFNMEMCACHEDTOR pfnDtor, void *pvUser, uint32_t fFlags); + +/** + * Destroy a cache destroying and freeing allocated memory. + * + * @returns IPRT status code. + * @param hMemCache The cache handle. NIL is quietly (VINF_SUCCESS) + * ignored. + */ +RTDECL(int) RTMemCacheDestroy(RTMEMCACHE hMemCache); + +/** + * Allocate an object. + * + * @returns Pointer to the allocated cache object. + * @param hMemCache The cache handle. + */ +RTDECL(void *) RTMemCacheAlloc(RTMEMCACHE hMemCache); + +/** + * Allocate an object and return a proper status code. + * + * @returns IPRT status code. + * @retval VERR_MEM_CACHE_MAX_SIZE if we've reached maximum size (see + * RTMemCacheCreate). + * @retval VERR_NO_MEMORY if we failed to allocate more memory for the cache. + * + * @param hMemCache The cache handle. + * @param ppvObj Where to return the object. + */ +RTDECL(int) RTMemCacheAllocEx(RTMEMCACHE hMemCache, void **ppvObj); + +/** + * Free an object previously returned by RTMemCacheAlloc or RTMemCacheAllocEx. + * + * @param hMemCache The cache handle. + * @param pvObj The object to free. NULL is fine. + */ +RTDECL(void) RTMemCacheFree(RTMEMCACHE hMemCache, void *pvObj); + +/** @} */ + +RT_C_DECLS_END + +#endif /* !IPRT_INCLUDED_memcache_h */ + |