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source: vbox/trunk/include/iprt/memcache.h@ 47988

Last change on this file since 47988 was 45903, checked in by vboxsync, 12 years ago

memcache.h/.cpp: doc updates

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1/** @file
2 * IPRT - Memory Object Allocation Cache.
3 */
4
5/*
6 * Copyright (C) 2006-2010 Oracle Corporation
7 *
8 * This file is part of VirtualBox Open Source Edition (OSE), as
9 * available from http://www.virtualbox.org. This file is free software;
10 * you can redistribute it and/or modify it under the terms of the GNU
11 * General Public License (GPL) as published by the Free Software
12 * Foundation, in version 2 as it comes in the "COPYING" file of the
13 * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
14 * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
15 *
16 * The contents of this file may alternatively be used under the terms
17 * of the Common Development and Distribution License Version 1.0
18 * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
19 * VirtualBox OSE distribution, in which case the provisions of the
20 * CDDL are applicable instead of those of the GPL.
21 *
22 * You may elect to license modified versions of this file under the
23 * terms and conditions of either the GPL or the CDDL or both.
24 */
25
26#ifndef ___iprt_memcache_h
27#define ___iprt_memcache_h
28
29
30#include <iprt/cdefs.h>
31#include <iprt/types.h>
32
33RT_C_DECLS_BEGIN
34
35
36/** @defgroup grp_rt_memcache RTMemCache - Memory Object Allocation Cache
37 * @ingroup grp_rt
38 *
39 * Optimized allocation, initialization, freeing and destruction of memory
40 * objects of the same kind and size. Objects are constructed once, then
41 * allocated and freed one or more times, until finally destructed together with
42 * the cache (RTMemCacheDestroy). It's expected behavior, even when pfnCtor is
43 * NULL, that the user will be store information that should be persistent
44 * across RTMemCacheFree calls.
45 *
46 * The objects are zeroed prior to calling pfnCtor. For obvious reasons, the
47 * objects are not touched by the cache after that, so that RTMemCacheAlloc will
48 * return the object in the same state as when it as handed to RTMemCacheFree.
49 *
50 * @todo A callback for the reuse (at alloc time) might be of interest.
51 *
52 * @{
53 */
54
55/** A memory cache handle. */
56typedef R3R0PTRTYPE(struct RTMEMCACHEINT *) RTMEMCACHE;
57/** Pointer to a memory cache handle. */
58typedef RTMEMCACHE *PRTMEMCACHE;
59/** Nil memory cache handle. */
60#define NIL_RTMEMCACHE ((RTMEMCACHE)0)
61
62
63/**
64 * Object constructor.
65 *
66 * This is called for when an element is allocated for the first time.
67 *
68 * @returns IPRT status code.
69 * @param hMemCache The cache handle.
70 * @param pvObj The memory object that should be initialized.
71 * @param pvUser The user argument.
72 *
73 * @remarks No serialization is performed.
74 */
75typedef DECLCALLBACK(int) FNMEMCACHECTOR(RTMEMCACHE hMemCache, void *pvObj, void *pvUser);
76/** Pointer to an object constructor for the memory cache. */
77typedef FNMEMCACHECTOR *PFNMEMCACHECTOR;
78
79/**
80 * Object destructor.
81 *
82 * This is called when we're shrinking or destroying the cache.
83 *
84 * @param hMemCache The cache handle.
85 * @param pvObj The memory object that should be initialized.
86 * @param pvUser The user argument.
87 *
88 * @remarks No serialization is performed.
89 */
90typedef DECLCALLBACK(void) FNMEMCACHEDTOR(RTMEMCACHE hMemCache, void *pvObj, void *pvUser);
91/** Pointer to an object destructor for the memory cache. */
92typedef FNMEMCACHEDTOR *PFNMEMCACHEDTOR;
93
94
95/**
96 * Create an allocation cache for fixed size memory objects.
97 *
98 * @returns IPRT status code.
99 * @param phMemCache Where to return the cache handle.
100 * @param cbObject The size of one memory object.
101 * @param cbAlignment The object alignment. This must be a power of
102 * two. The higest alignment is 64. If set to 0,
103 * a sensible alignment value will be derived from
104 * the object size.
105 * @param cMaxObjects The maximum cache size. Pass UINT32_MAX if unsure.
106 * @param pfnCtor Object constructor callback. Optional.
107 * @param pfnDtor Object destructor callback. Optional.
108 * @param pvUser User argument for the two callbacks.
109 * @param fFlags Flags reserved for future use. Must be zero.
110 */
111RTDECL(int) RTMemCacheCreate(PRTMEMCACHE phMemCache, size_t cbObject, size_t cbAlignment, uint32_t cMaxObjects,
112 PFNMEMCACHECTOR pfnCtor, PFNMEMCACHEDTOR pfnDtor, void *pvUser, uint32_t fFlags);
113
114/**
115 * Destroy a cache destroying and freeing allocated memory.
116 *
117 * @returns IPRT status code.
118 * @param hMemCache The cache handle. NIL is quietly (VINF_SUCCESS)
119 * ignored.
120 */
121RTDECL(int) RTMemCacheDestroy(RTMEMCACHE hMemCache);
122
123/**
124 * Allocate an object.
125 *
126 * @returns Pointer to the allocated cache object.
127 * @param hMemCache The cache handle.
128 */
129RTDECL(void *) RTMemCacheAlloc(RTMEMCACHE hMemCache);
130
131/**
132 * Allocate an object and return a proper status code.
133 *
134 * @returns IPRT status code.
135 * @retval VERR_MEM_CACHE_MAX_SIZE if we've reached maximum size (see
136 * RTMemCacheCreate).
137 * @retval VERR_NO_MEMORY if we failed to allocate more memory for the cache.
138 *
139 * @param hMemCache The cache handle.
140 * @param ppvObj Where to return the object.
141 */
142RTDECL(int) RTMemCacheAllocEx(RTMEMCACHE hMemCache, void **ppvObj);
143
144/**
145 * Free an object previously returned by RTMemCacheAlloc or RTMemCacheAllocEx.
146 *
147 * @param hMemCache The cache handle.
148 * @param pvObj The object to free. NULL is fine.
149 */
150RTDECL(void) RTMemCacheFree(RTMEMCACHE hMemCache, void *pvObj);
151
152/** @} */
153
154RT_C_DECLS_END
155
156#endif
157
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