include/iprt/circbuf.h

   1 /** @file
   2  * IPRT - Lock Free Circular Buffer
   3  */
   4
   5 /*
   6  * Copyright (C) 2010-2024 Oracle and/or its affiliates.
   7  *
   8  * This file is part of VirtualBox base platform packages, as
   9  * available from https://www.virtualbox.org.
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public License
  13  * as published by the Free Software Foundation, in version 3 of the
  14  * License.
  15  *
  16  * This program is distributed in the hope that it will be useful, but
  17  * WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  19  * General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program; if not, see <https://www.gnu.org/licenses>.
  23  *
  24  * The contents of this file may alternatively be used under the terms
  25  * of the Common Development and Distribution License Version 1.0
  26  * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
  27  * in the VirtualBox distribution, in which case the provisions of the
  28  * CDDL are applicable instead of those of the GPL.
  29  *
  30  * You may elect to license modified versions of this file under the
  31  * terms and conditions of either the GPL or the CDDL or both.
  32  *
  33  * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
  34  */
  35
  36 #ifndef IPRT_INCLUDED_circbuf_h
  37 #define IPRT_INCLUDED_circbuf_h
  38 #ifndef RT_WITHOUT_PRAGMA_ONCE
  39 # pragma once
  40 #endif
  41
  42 #include <iprt/types.h>
  43
  44 /** @defgroup grp_rt_circbuf    RTCircBuf - Lock Free Circular Buffer
  45  * @ingroup grp_rt
  46  *
  47  * Implementation of a lock free circular buffer which could be used in a multi
  48  * threaded environment. Note that only the acquire, release and getter
  49  * functions are threading aware. So don't use reset if the circular buffer is
  50  * still in use.
  51  *
  52  * @{
  53  */
  54
  55 RT_C_DECLS_BEGIN
  56
  57 /** Pointer to a circular buffer (abstract). */
  58 typedef struct RTCIRCBUF *PRTCIRCBUF;
  59
  60 /**
  61  * Create a circular buffer.
  62  *
  63  * @returns IPRT status code.
  64  *
  65  * @param   ppBuf          Where to store the buffer.
  66  * @param   cbSize         The size of the new buffer.
  67  */
  68 RTDECL(int) RTCircBufCreate(PRTCIRCBUF *ppBuf, size_t cbSize);
  69
  70 /**
  71  * Destroy the circular buffer.
  72  *
  73  * @param   pBuf           The buffer to destroy.  NULL is ignored.
  74  */
  75 RTDECL(void) RTCircBufDestroy(PRTCIRCBUF pBuf);
  76
  77 /**
  78  * Reset all position information in the circular buffer.
  79  *
  80  * @note This function is not multi threading aware.
  81  *
  82  * @param   pBuf           The buffer to reset.
  83  */
  84 RTDECL(void) RTCircBufReset(PRTCIRCBUF pBuf);
  85
  86 /**
  87  * Returns the current free space of the buffer.
  88  *
  89  * @param   pBuf           The buffer to query.
  90  */
  91 RTDECL(size_t) RTCircBufFree(PRTCIRCBUF pBuf);
  92
  93 /**
  94  * Returns the current used space of the buffer.
  95  *
  96  * @param   pBuf           The buffer to query.
  97  */
  98 RTDECL(size_t) RTCircBufUsed(PRTCIRCBUF pBuf);
  99
 100 /**
 101  * Returns the size of the buffer.
 102  *
 103  * @param   pBuf           The buffer to query.
 104  */
 105 RTDECL(size_t) RTCircBufSize(PRTCIRCBUF pBuf);
 106
 107 RTDECL(bool) RTCircBufIsReading(PRTCIRCBUF pBuf);
 108 RTDECL(bool) RTCircBufIsWriting(PRTCIRCBUF pBuf);
 109
 110 /**
 111  * Returns the current read offset (in bytes) within the buffer.
 112  *
 113  * @param   pBuf           The buffer to query.
 114  */
 115 RTDECL(size_t) RTCircBufOffsetRead(PRTCIRCBUF pBuf);
 116
 117 /**
 118  * Returns the current write offset (in bytes) within the buffer.
 119  *
 120  * @param   pBuf           The buffer to query.
 121  */
 122 RTDECL(size_t) RTCircBufOffsetWrite(PRTCIRCBUF pBuf);
 123
 124 /**
 125  * Acquire a block of the circular buffer for reading.
 126  *
 127  * @param   pBuf           The buffer to acquire from.
 128  * @param   cbReqSize      The requested size of the block.
 129  * @param   ppvStart       The resulting memory pointer.
 130  * @param   pcbSize        The resulting size of the memory pointer.
 131  */
 132 RTDECL(void) RTCircBufAcquireReadBlock(PRTCIRCBUF pBuf, size_t cbReqSize, void **ppvStart, size_t *pcbSize);
 133
 134 /**
 135  * Release a block which was acquired by RTCircBufAcquireReadBlock.
 136  *
 137  * @param   pBuf           The buffer to acquire from.
 138  * @param   cbSize         The size of the block.
 139  */
 140 RTDECL(void) RTCircBufReleaseReadBlock(PRTCIRCBUF pBuf, size_t cbSize);
 141
 142 /**
 143  * Acquire a block of the circular buffer for writing.
 144  *
 145  * @param   pBuf           The buffer to acquire from.
 146  * @param   cbReqSize      The requested size of the block.
 147  * @param   ppvStart       The resulting memory pointer.
 148  * @param   pcbSize        The resulting size of the memory pointer.
 149  */
 150 RTDECL(void) RTCircBufAcquireWriteBlock(PRTCIRCBUF pBuf, size_t cbReqSize, void **ppvStart, size_t *pcbSize);
 151
 152 /**
 153  * Release a block which was acquired by RTCircBufAcquireWriteBlock.
 154  *
 155  * @param   pBuf           The buffer to acquire from.
 156  * @param   cbSize         The size of the block.
 157  */
 158 RTDECL(void) RTCircBufReleaseWriteBlock(PRTCIRCBUF pBuf, size_t cbSize);
 159
 160 RT_C_DECLS_END
 161
 162 /** @} */
 163
 164 #endif /* !IPRT_INCLUDED_circbuf_h */
 165