| 1 | /** @file
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| 2 | * IPRT - Memory Object Allocation Cache.
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| 3 | */
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| 4 |
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| 5 | /*
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| 6 | * Copyright (C) 2006-2022 Oracle and/or its affiliates.
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| 7 | *
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| 8 | * This file is part of VirtualBox base platform packages, as
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| 9 | * available from https://www.virtualbox.org.
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| 10 | *
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| 11 | * This program is free software; you can redistribute it and/or
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| 12 | * modify it under the terms of the GNU General Public License
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| 13 | * as published by the Free Software Foundation, in version 3 of the
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| 14 | * License.
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| 15 | *
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| 16 | * This program is distributed in the hope that it will be useful, but
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| 17 | * WITHOUT ANY WARRANTY; without even the implied warranty of
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| 18 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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| 19 | * General Public License for more details.
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| 20 | *
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| 21 | * You should have received a copy of the GNU General Public License
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| 22 | * along with this program; if not, see <https://www.gnu.org/licenses>.
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| 23 | *
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| 24 | * The contents of this file may alternatively be used under the terms
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| 25 | * of the Common Development and Distribution License Version 1.0
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| 26 | * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
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| 27 | * in the VirtualBox distribution, in which case the provisions of the
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| 28 | * CDDL are applicable instead of those of the GPL.
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| 29 | *
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| 30 | * You may elect to license modified versions of this file under the
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| 31 | * terms and conditions of either the GPL or the CDDL or both.
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| 32 | *
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| 33 | * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
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| 34 | */
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| 35 |
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| 36 | #ifndef IPRT_INCLUDED_memcache_h
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| 37 | #define IPRT_INCLUDED_memcache_h
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| 38 | #ifndef RT_WITHOUT_PRAGMA_ONCE
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| 39 | # pragma once
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| 40 | #endif
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| 41 |
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| 42 |
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| 43 | #include <iprt/cdefs.h>
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| 44 | #include <iprt/types.h>
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| 45 |
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| 46 | RT_C_DECLS_BEGIN
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| 47 |
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| 48 |
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| 49 | /** @defgroup grp_rt_memcache RTMemCache - Memory Object Allocation Cache
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| 50 | * @ingroup grp_rt
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| 51 | *
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| 52 | * Optimized allocation, initialization, freeing and destruction of memory
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| 53 | * objects of the same kind and size. Objects are constructed once, then
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| 54 | * allocated and freed one or more times, until finally destructed together with
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| 55 | * the cache (RTMemCacheDestroy). It's expected behavior, even when pfnCtor is
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| 56 | * NULL, that the user will be store information that should be persistent
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| 57 | * across RTMemCacheFree calls.
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| 58 | *
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| 59 | * The objects are zeroed prior to calling pfnCtor. For obvious reasons, the
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| 60 | * objects are not touched by the cache after that, so that RTMemCacheAlloc will
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| 61 | * return the object in the same state as when it as handed to RTMemCacheFree.
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| 62 | *
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| 63 | * @todo A callback for the reuse (at alloc time) might be of interest.
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| 64 | *
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| 65 | * @{
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| 66 | */
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| 67 |
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| 68 | /** A memory cache handle. */
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| 69 | typedef R3R0PTRTYPE(struct RTMEMCACHEINT *) RTMEMCACHE;
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| 70 | /** Pointer to a memory cache handle. */
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| 71 | typedef RTMEMCACHE *PRTMEMCACHE;
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| 72 | /** Nil memory cache handle. */
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| 73 | #define NIL_RTMEMCACHE ((RTMEMCACHE)0)
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| 74 |
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| 75 |
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| 76 | /**
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| 77 | * Object constructor.
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| 78 | *
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| 79 | * This is called for when an element is allocated for the first time.
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| 80 | *
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| 81 | * @returns IPRT status code.
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| 82 | * @param hMemCache The cache handle.
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| 83 | * @param pvObj The memory object that should be initialized.
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| 84 | * @param pvUser The user argument.
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| 85 | *
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| 86 | * @remarks No serialization is performed.
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| 87 | */
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| 88 | typedef DECLCALLBACKTYPE(int, FNMEMCACHECTOR,(RTMEMCACHE hMemCache, void *pvObj, void *pvUser));
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| 89 | /** Pointer to an object constructor for the memory cache. */
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| 90 | typedef FNMEMCACHECTOR *PFNMEMCACHECTOR;
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| 91 |
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| 92 | /**
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| 93 | * Object destructor.
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| 94 | *
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| 95 | * This is called when we're shrinking or destroying the cache.
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| 96 | *
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| 97 | * @param hMemCache The cache handle.
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| 98 | * @param pvObj The memory object that should be initialized.
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| 99 | * @param pvUser The user argument.
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| 100 | *
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| 101 | * @remarks No serialization is performed.
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| 102 | */
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| 103 | typedef DECLCALLBACKTYPE(void, FNMEMCACHEDTOR,(RTMEMCACHE hMemCache, void *pvObj, void *pvUser));
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| 104 | /** Pointer to an object destructor for the memory cache. */
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| 105 | typedef FNMEMCACHEDTOR *PFNMEMCACHEDTOR;
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| 106 |
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| 107 |
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| 108 | /**
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| 109 | * Create an allocation cache for fixed size memory objects.
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| 110 | *
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| 111 | * @returns IPRT status code.
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| 112 | * @param phMemCache Where to return the cache handle.
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| 113 | * @param cbObject The size of one memory object.
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| 114 | * @param cbAlignment The object alignment. This must be a power of
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| 115 | * two. The higest alignment is 64. If set to 0,
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| 116 | * a sensible alignment value will be derived from
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| 117 | * the object size.
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| 118 | * @param cMaxObjects The maximum cache size. Pass UINT32_MAX if unsure.
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| 119 | * @param pfnCtor Object constructor callback. Optional.
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| 120 | * @param pfnDtor Object destructor callback. Optional.
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| 121 | * @param pvUser User argument for the two callbacks.
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| 122 | * @param fFlags Flags reserved for future use. Must be zero.
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| 123 | */
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| 124 | RTDECL(int) RTMemCacheCreate(PRTMEMCACHE phMemCache, size_t cbObject, size_t cbAlignment, uint32_t cMaxObjects,
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| 125 | PFNMEMCACHECTOR pfnCtor, PFNMEMCACHEDTOR pfnDtor, void *pvUser, uint32_t fFlags);
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| 126 |
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| 127 | /**
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| 128 | * Destroy a cache destroying and freeing allocated memory.
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| 129 | *
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| 130 | * @returns IPRT status code.
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| 131 | * @param hMemCache The cache handle. NIL is quietly (VINF_SUCCESS)
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| 132 | * ignored.
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| 133 | */
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| 134 | RTDECL(int) RTMemCacheDestroy(RTMEMCACHE hMemCache);
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| 135 |
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| 136 | /**
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| 137 | * Allocate an object.
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| 138 | *
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| 139 | * @returns Pointer to the allocated cache object.
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| 140 | * @param hMemCache The cache handle.
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| 141 | */
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| 142 | RTDECL(void *) RTMemCacheAlloc(RTMEMCACHE hMemCache);
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| 143 |
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| 144 | /**
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| 145 | * Allocate an object and return a proper status code.
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| 146 | *
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| 147 | * @returns IPRT status code.
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| 148 | * @retval VERR_MEM_CACHE_MAX_SIZE if we've reached maximum size (see
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| 149 | * RTMemCacheCreate).
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| 150 | * @retval VERR_NO_MEMORY if we failed to allocate more memory for the cache.
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| 151 | *
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| 152 | * @param hMemCache The cache handle.
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| 153 | * @param ppvObj Where to return the object.
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| 154 | */
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| 155 | RTDECL(int) RTMemCacheAllocEx(RTMEMCACHE hMemCache, void **ppvObj);
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| 156 |
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| 157 | /**
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| 158 | * Free an object previously returned by RTMemCacheAlloc or RTMemCacheAllocEx.
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| 159 | *
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| 160 | * @param hMemCache The cache handle.
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| 161 | * @param pvObj The object to free. NULL is fine.
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| 162 | */
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| 163 | RTDECL(void) RTMemCacheFree(RTMEMCACHE hMemCache, void *pvObj);
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| 164 |
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| 165 | /** @} */
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| 166 |
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| 167 | RT_C_DECLS_END
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| 168 |
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| 169 | #endif /* !IPRT_INCLUDED_memcache_h */
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| 170 |
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