[10940] | 1 | /** @file
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| 2 | * IPRT - Execute Once.
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| 3 | */
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| 4 |
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| 5 | /*
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[76553] | 6 | * Copyright (C) 2006-2019 Oracle Corporation
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[10940] | 7 | *
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| 8 | * This file is part of VirtualBox Open Source Edition (OSE), as
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| 9 | * available from http://www.virtualbox.org. This file is free software;
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| 10 | * you can redistribute it and/or modify it under the terms of the GNU
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| 11 | * General Public License (GPL) as published by the Free Software
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| 12 | * Foundation, in version 2 as it comes in the "COPYING" file of the
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| 13 | * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
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| 14 | * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
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| 15 | *
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| 16 | * The contents of this file may alternatively be used under the terms
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| 17 | * of the Common Development and Distribution License Version 1.0
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| 18 | * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
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| 19 | * VirtualBox OSE distribution, in which case the provisions of the
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| 20 | * CDDL are applicable instead of those of the GPL.
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| 21 | *
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| 22 | * You may elect to license modified versions of this file under the
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| 23 | * terms and conditions of either the GPL or the CDDL or both.
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| 24 | */
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| 25 |
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[76557] | 26 | #ifndef IPRT_INCLUDED_once_h
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| 27 | #define IPRT_INCLUDED_once_h
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[76507] | 28 | #ifndef RT_WITHOUT_PRAGMA_ONCE
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| 29 | # pragma once
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| 30 | #endif
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[10940] | 31 |
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| 32 | #include <iprt/cdefs.h>
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| 33 | #include <iprt/types.h>
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[37316] | 34 | #include <iprt/asm.h>
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[76417] | 35 | #include <iprt/errcore.h>
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[43879] | 36 | #include <iprt/list.h>
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[10940] | 37 |
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[20374] | 38 | RT_C_DECLS_BEGIN
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[10940] | 39 |
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| 40 | /** @defgroup grp_rt_once RTOnce - Execute Once
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| 41 | * @ingroup grp_rt
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| 42 | * @{
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| 43 | */
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| 44 |
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| 45 | /**
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[43879] | 46 | * Callback that gets executed once.
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| 47 | *
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| 48 | * @returns IPRT style status code, RTOnce returns this.
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| 49 | *
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| 50 | * @param pvUser The user parameter.
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| 51 | */
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| 52 | typedef DECLCALLBACK(int32_t) FNRTONCE(void *pvUser);
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| 53 | /** Pointer to a FNRTONCE. */
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| 54 | typedef FNRTONCE *PFNRTONCE;
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| 55 |
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| 56 | /**
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| 57 | * Callback that gets executed on IPRT/process termination.
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| 58 | *
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| 59 | * @param pvUser The user parameter.
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| 60 | * @param fLazyCleanUpOk Indicates whether lazy clean-up is OK (see
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| 61 | * initterm.h).
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| 62 | */
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| 63 | typedef DECLCALLBACK(void) FNRTONCECLEANUP(void *pvUser, bool fLazyCleanUpOk);
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| 64 | /** Pointer to a FNRTONCE. */
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| 65 | typedef FNRTONCECLEANUP *PFNRTONCECLEANUP;
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| 66 |
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| 67 | /**
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[10940] | 68 | * Execute once structure.
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| 69 | *
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| 70 | * This is typically a global variable that is statically initialized
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| 71 | * by RTONCE_INITIALIZER.
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| 72 | */
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| 73 | typedef struct RTONCE
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| 74 | {
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| 75 | /** Event semaphore that the other guys are blocking on. */
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[43879] | 76 | RTSEMEVENTMULTI volatile hEventMulti;
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[10940] | 77 | /** Reference counter for hEventMulti. */
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[43879] | 78 | int32_t volatile cEventRefs;
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| 79 | /** See RTONCESTATE. */
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| 80 | int32_t volatile iState;
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[10940] | 81 | /** The return code of pfnOnce. */
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[43879] | 82 | int32_t volatile rc;
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| 83 |
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| 84 | /** Pointer to the clean-up function. */
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| 85 | PFNRTONCECLEANUP pfnCleanUp;
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| 86 | /** Argument to hand to the clean-up function. */
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| 87 | void *pvUser;
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| 88 | /** Clean-up list entry. */
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| 89 | RTLISTNODE CleanUpNode;
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[10940] | 90 | } RTONCE;
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| 91 | /** Pointer to a execute once struct. */
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| 92 | typedef RTONCE *PRTONCE;
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| 93 |
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[33262] | 94 | /**
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| 95 | * The execute once statemachine.
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| 96 | */
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| 97 | typedef enum RTONCESTATE
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| 98 | {
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| 99 | /** RTOnce() has not been called.
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| 100 | * Next: NO_SEM */
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| 101 | RTONCESTATE_UNINITIALIZED = 1,
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| 102 | /** RTOnce() is busy, no race.
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| 103 | * Next: CREATING_SEM, DONE */
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| 104 | RTONCESTATE_BUSY_NO_SEM,
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| 105 | /** More than one RTOnce() caller is busy.
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| 106 | * Next: BUSY_HAVE_SEM, BUSY_SPIN, DONE_CREATING_SEM, DONE */
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| 107 | RTONCESTATE_BUSY_CREATING_SEM,
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| 108 | /** More than one RTOnce() caller, the first is busy, the others are
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| 109 | * waiting.
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| 110 | * Next: DONE */
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| 111 | RTONCESTATE_BUSY_HAVE_SEM,
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| 112 | /** More than one RTOnce() caller, the first is busy, the others failed to
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| 113 | * create a semaphore and are spinning.
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| 114 | * Next: DONE */
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| 115 | RTONCESTATE_BUSY_SPIN,
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| 116 | /** More than one RTOnce() caller, the first has completed, the others
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| 117 | * are busy creating the semaphore.
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| 118 | * Next: DONE_HAVE_SEM */
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| 119 | RTONCESTATE_DONE_CREATING_SEM,
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| 120 | /** More than one RTOnce() caller, the first is busy grabbing the
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| 121 | * semaphore, while the others are waiting.
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| 122 | * Next: DONE */
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| 123 | RTONCESTATE_DONE_HAVE_SEM,
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| 124 | /** The execute once stuff has completed. */
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| 125 | RTONCESTATE_DONE = 16
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| 126 | } RTONCESTATE;
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| 127 |
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[10940] | 128 | /** Static initializer for RTONCE variables. */
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[43879] | 129 | #define RTONCE_INITIALIZER \
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| 130 | { NIL_RTSEMEVENTMULTI, 0, RTONCESTATE_UNINITIALIZED, VERR_INTERNAL_ERROR, NULL, NULL, { NULL, NULL } }
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[10940] | 131 |
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| 132 |
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| 133 | /**
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[43879] | 134 | * Serializes execution of the pfnOnce function, making sure it's
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| 135 | * executed exactly once and that nobody returns from RTOnce before
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| 136 | * it has executed successfully.
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[10940] | 137 | *
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[43879] | 138 | * @returns IPRT like status code returned by pfnOnce.
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[10940] | 139 | *
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[43879] | 140 | * @param pOnce Pointer to the execute once variable.
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| 141 | * @param pfnOnce The function to executed once.
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| 142 | * @param pfnCleanUp The function that will be doing the cleaning up.
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| 143 | * Optional.
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| 144 | * @param pvUser The user parameter for pfnOnce.
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[10940] | 145 | */
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[43879] | 146 | RTDECL(int) RTOnceSlow(PRTONCE pOnce, PFNRTONCE pfnOnce, FNRTONCECLEANUP pfnCleanUp, void *pvUser);
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[10940] | 147 |
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| 148 | /**
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| 149 | * Serializes execution of the pfnOnce function, making sure it's
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| 150 | * executed exactly once and that nobody returns from RTOnce before
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| 151 | * it has executed successfully.
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| 152 | *
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| 153 | * @returns IPRT like status code returned by pfnOnce.
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| 154 | *
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| 155 | * @param pOnce Pointer to the execute once variable.
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| 156 | * @param pfnOnce The function to executed once.
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[43879] | 157 | * @param pvUser The user parameter for pfnOnce.
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[10940] | 158 | */
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[43879] | 159 | DECLINLINE(int) RTOnce(PRTONCE pOnce, PFNRTONCE pfnOnce, void *pvUser)
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| 160 | {
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| 161 | int32_t iState = ASMAtomicUoReadS32(&pOnce->iState);
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| 162 | if (RT_LIKELY( iState == RTONCESTATE_DONE
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| 163 | || iState == RTONCESTATE_DONE_CREATING_SEM
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| 164 | || iState == RTONCESTATE_DONE_HAVE_SEM ))
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| 165 | return ASMAtomicUoReadS32(&pOnce->rc);
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| 166 | return RTOnceSlow(pOnce, pfnOnce, NULL, pvUser);
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| 167 | }
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[10940] | 168 |
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[19896] | 169 | /**
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[43879] | 170 | * Execute pfnOnce once and register a termination clean-up callback.
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| 171 | *
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[37316] | 172 | * Serializes execution of the pfnOnce function, making sure it's
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| 173 | * executed exactly once and that nobody returns from RTOnce before
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| 174 | * it has executed successfully.
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| 175 | *
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| 176 | * @returns IPRT like status code returned by pfnOnce.
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| 177 | *
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| 178 | * @param pOnce Pointer to the execute once variable.
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| 179 | * @param pfnOnce The function to executed once.
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[43879] | 180 | * @param pfnCleanUp The function that will be doing the cleaning up.
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| 181 | * @param pvUser The user parameter for pfnOnce.
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[37316] | 182 | */
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[43879] | 183 | DECLINLINE(int) RTOnceEx(PRTONCE pOnce, PFNRTONCE pfnOnce, PFNRTONCECLEANUP pfnCleanUp, void *pvUser)
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[37316] | 184 | {
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| 185 | int32_t iState = ASMAtomicUoReadS32(&pOnce->iState);
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| 186 | if (RT_LIKELY( iState == RTONCESTATE_DONE
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| 187 | || iState == RTONCESTATE_DONE_CREATING_SEM
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| 188 | || iState == RTONCESTATE_DONE_HAVE_SEM ))
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| 189 | return ASMAtomicUoReadS32(&pOnce->rc);
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[43879] | 190 | return RTOnceSlow(pOnce, pfnOnce, pfnCleanUp, pvUser);
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[37316] | 191 | }
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| 192 |
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[43879] | 193 |
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[37316] | 194 | /**
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[19896] | 195 | * Resets an execute once variable.
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| 196 | *
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| 197 | * The caller is responsible for making sure there are no concurrent accesses to
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| 198 | * the execute once variable.
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| 199 | *
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| 200 | * @param pOnce Pointer to the execute once variable.
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| 201 | */
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| 202 | RTDECL(void) RTOnceReset(PRTONCE pOnce);
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| 203 |
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[10940] | 204 | /** @} */
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| 205 |
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[20374] | 206 | RT_C_DECLS_END
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[10940] | 207 |
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[76585] | 208 | #endif /* !IPRT_INCLUDED_once_h */
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[10940] | 209 |
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