170 lines
6 KiB
C
170 lines
6 KiB
C
/** @file
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* IPRT - Memory Object Allocation Cache.
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*/
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/*
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* Copyright (C) 2006-2023 Oracle and/or its affiliates.
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*
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* This file is part of VirtualBox base platform packages, as
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* available from https://www.virtualbox.org.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation, in version 3 of the
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* License.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <https://www.gnu.org/licenses>.
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*
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* The contents of this file may alternatively be used under the terms
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* of the Common Development and Distribution License Version 1.0
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* (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
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* in the VirtualBox distribution, in which case the provisions of the
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* CDDL are applicable instead of those of the GPL.
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*
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* You may elect to license modified versions of this file under the
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* terms and conditions of either the GPL or the CDDL or both.
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*
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* SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
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*/
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#ifndef IPRT_INCLUDED_memcache_h
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#define IPRT_INCLUDED_memcache_h
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#ifndef RT_WITHOUT_PRAGMA_ONCE
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# pragma once
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#endif
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#include <iprt/cdefs.h>
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#include <iprt/types.h>
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RT_C_DECLS_BEGIN
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/** @defgroup grp_rt_memcache RTMemCache - Memory Object Allocation Cache
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* @ingroup grp_rt
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*
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* Optimized allocation, initialization, freeing and destruction of memory
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* objects of the same kind and size. Objects are constructed once, then
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* allocated and freed one or more times, until finally destructed together with
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* the cache (RTMemCacheDestroy). It's expected behavior, even when pfnCtor is
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* NULL, that the user will be store information that should be persistent
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* across RTMemCacheFree calls.
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*
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* The objects are zeroed prior to calling pfnCtor. For obvious reasons, the
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* objects are not touched by the cache after that, so that RTMemCacheAlloc will
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* return the object in the same state as when it as handed to RTMemCacheFree.
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*
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* @todo A callback for the reuse (at alloc time) might be of interest.
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*
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* @{
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*/
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/** A memory cache handle. */
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typedef R3R0PTRTYPE(struct RTMEMCACHEINT *) RTMEMCACHE;
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/** Pointer to a memory cache handle. */
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typedef RTMEMCACHE *PRTMEMCACHE;
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/** Nil memory cache handle. */
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#define NIL_RTMEMCACHE ((RTMEMCACHE)0)
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/**
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* Object constructor.
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*
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* This is called for when an element is allocated for the first time.
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*
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* @returns IPRT status code.
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* @param hMemCache The cache handle.
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* @param pvObj The memory object that should be initialized.
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* @param pvUser The user argument.
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*
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* @remarks No serialization is performed.
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*/
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typedef DECLCALLBACKTYPE(int, FNMEMCACHECTOR,(RTMEMCACHE hMemCache, void *pvObj, void *pvUser));
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/** Pointer to an object constructor for the memory cache. */
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typedef FNMEMCACHECTOR *PFNMEMCACHECTOR;
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/**
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* Object destructor.
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*
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* This is called when we're shrinking or destroying the cache.
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*
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* @param hMemCache The cache handle.
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* @param pvObj The memory object that should be initialized.
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* @param pvUser The user argument.
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*
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* @remarks No serialization is performed.
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*/
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typedef DECLCALLBACKTYPE(void, FNMEMCACHEDTOR,(RTMEMCACHE hMemCache, void *pvObj, void *pvUser));
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/** Pointer to an object destructor for the memory cache. */
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typedef FNMEMCACHEDTOR *PFNMEMCACHEDTOR;
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/**
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* Create an allocation cache for fixed size memory objects.
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*
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* @returns IPRT status code.
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* @param phMemCache Where to return the cache handle.
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* @param cbObject The size of one memory object.
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* @param cbAlignment The object alignment. This must be a power of
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* two. The higest alignment is 64. If set to 0,
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* a sensible alignment value will be derived from
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* the object size.
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* @param cMaxObjects The maximum cache size. Pass UINT32_MAX if unsure.
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* @param pfnCtor Object constructor callback. Optional.
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* @param pfnDtor Object destructor callback. Optional.
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* @param pvUser User argument for the two callbacks.
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* @param fFlags Flags reserved for future use. Must be zero.
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*/
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RTDECL(int) RTMemCacheCreate(PRTMEMCACHE phMemCache, size_t cbObject, size_t cbAlignment, uint32_t cMaxObjects,
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PFNMEMCACHECTOR pfnCtor, PFNMEMCACHEDTOR pfnDtor, void *pvUser, uint32_t fFlags);
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/**
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* Destroy a cache destroying and freeing allocated memory.
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*
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* @returns IPRT status code.
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* @param hMemCache The cache handle. NIL is quietly (VINF_SUCCESS)
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* ignored.
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*/
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RTDECL(int) RTMemCacheDestroy(RTMEMCACHE hMemCache);
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/**
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* Allocate an object.
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*
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* @returns Pointer to the allocated cache object.
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* @param hMemCache The cache handle.
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*/
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RTDECL(void *) RTMemCacheAlloc(RTMEMCACHE hMemCache);
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/**
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* Allocate an object and return a proper status code.
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*
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* @returns IPRT status code.
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* @retval VERR_MEM_CACHE_MAX_SIZE if we've reached maximum size (see
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* RTMemCacheCreate).
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* @retval VERR_NO_MEMORY if we failed to allocate more memory for the cache.
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*
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* @param hMemCache The cache handle.
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* @param ppvObj Where to return the object.
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*/
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RTDECL(int) RTMemCacheAllocEx(RTMEMCACHE hMemCache, void **ppvObj);
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/**
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* Free an object previously returned by RTMemCacheAlloc or RTMemCacheAllocEx.
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*
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* @param hMemCache The cache handle.
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* @param pvObj The object to free. NULL is fine.
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*/
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RTDECL(void) RTMemCacheFree(RTMEMCACHE hMemCache, void *pvObj);
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/** @} */
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RT_C_DECLS_END
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#endif /* !IPRT_INCLUDED_memcache_h */
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