231 lines
7.6 KiB
C
231 lines
7.6 KiB
C
/** @file
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* IPRT - Execute Once.
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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_once_h
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#define IPRT_INCLUDED_once_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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#include <iprt/asm.h>
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#include <iprt/errcore.h>
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#include <iprt/list.h>
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RT_C_DECLS_BEGIN
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/** @defgroup grp_rt_once RTOnce - Execute Once
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* @ingroup grp_rt
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* @{
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*/
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/**
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* Callback that gets executed once.
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*
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* @returns IPRT style status code, RTOnce returns this.
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*
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* @param pvUser The user parameter.
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*/
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typedef DECLCALLBACKTYPE(int32_t, FNRTONCE,(void *pvUser));
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/** Pointer to a FNRTONCE. */
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typedef FNRTONCE *PFNRTONCE;
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/**
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* Callback that gets executed on IPRT/process termination.
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*
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* @param pvUser The user parameter.
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* @param fLazyCleanUpOk Indicates whether lazy clean-up is OK (see
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* initterm.h).
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*/
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typedef DECLCALLBACKTYPE(void, FNRTONCECLEANUP,(void *pvUser, bool fLazyCleanUpOk));
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/** Pointer to a FNRTONCE. */
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typedef FNRTONCECLEANUP *PFNRTONCECLEANUP;
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/**
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* Execute once structure.
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*
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* This is typically a global variable that is statically initialized
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* by RTONCE_INITIALIZER.
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*/
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typedef struct RTONCE
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{
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/** Event semaphore that the other guys are blocking on. */
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RTSEMEVENTMULTI volatile hEventMulti;
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/** Reference counter for hEventMulti. */
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int32_t volatile cEventRefs;
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/** See RTONCESTATE. */
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int32_t volatile iState;
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/** The return code of pfnOnce. */
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int32_t volatile rc;
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/** Pointer to the clean-up function. */
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PFNRTONCECLEANUP pfnCleanUp;
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/** Argument to hand to the clean-up function. */
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void *pvUser;
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/** Clean-up list entry. */
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RTLISTNODE CleanUpNode;
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} RTONCE;
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/** Pointer to a execute once struct. */
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typedef RTONCE *PRTONCE;
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/**
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* The execute once statemachine.
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*/
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typedef enum RTONCESTATE
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{
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/** RTOnce() has not been called.
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* Next: NO_SEM */
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RTONCESTATE_UNINITIALIZED = 1,
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/** RTOnce() is busy, no race.
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* Next: CREATING_SEM, DONE */
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RTONCESTATE_BUSY_NO_SEM,
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/** More than one RTOnce() caller is busy.
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* Next: BUSY_HAVE_SEM, BUSY_SPIN, DONE_CREATING_SEM, DONE */
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RTONCESTATE_BUSY_CREATING_SEM,
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/** More than one RTOnce() caller, the first is busy, the others are
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* waiting.
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* Next: DONE */
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RTONCESTATE_BUSY_HAVE_SEM,
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/** More than one RTOnce() caller, the first is busy, the others failed to
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* create a semaphore and are spinning.
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* Next: DONE */
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RTONCESTATE_BUSY_SPIN,
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/** More than one RTOnce() caller, the first has completed, the others
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* are busy creating the semaphore.
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* Next: DONE_HAVE_SEM */
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RTONCESTATE_DONE_CREATING_SEM,
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/** More than one RTOnce() caller, the first is busy grabbing the
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* semaphore, while the others are waiting.
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* Next: DONE */
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RTONCESTATE_DONE_HAVE_SEM,
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/** The execute once stuff has completed. */
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RTONCESTATE_DONE = 16
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} RTONCESTATE;
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/** Static initializer for RTONCE variables. */
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#define RTONCE_INITIALIZER \
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{ NIL_RTSEMEVENTMULTI, 0, RTONCESTATE_UNINITIALIZED, VERR_INTERNAL_ERROR, NULL, NULL, { NULL, NULL } }
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/**
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* Serializes execution of the pfnOnce function, making sure it's
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* executed exactly once and that nobody returns from RTOnce before
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* it has executed successfully.
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*
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* @returns IPRT like status code returned by pfnOnce.
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*
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* @param pOnce Pointer to the execute once variable.
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* @param pfnOnce The function to executed once.
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* @param pfnCleanUp The function that will be doing the cleaning up.
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* Optional.
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* @param pvUser The user parameter for pfnOnce.
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*/
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RTDECL(int) RTOnceSlow(PRTONCE pOnce, PFNRTONCE pfnOnce, FNRTONCECLEANUP pfnCleanUp, void *pvUser);
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/**
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* Serializes execution of the pfnOnce function, making sure it's
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* executed exactly once and that nobody returns from RTOnce before
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* it has executed successfully.
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*
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* @returns IPRT like status code returned by pfnOnce.
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*
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* @param pOnce Pointer to the execute once variable.
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* @param pfnOnce The function to executed once.
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* @param pvUser The user parameter for pfnOnce.
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*/
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DECLINLINE(int) RTOnce(PRTONCE pOnce, PFNRTONCE pfnOnce, void *pvUser)
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{
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int32_t iState = ASMAtomicUoReadS32(&pOnce->iState);
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if (RT_LIKELY( iState == RTONCESTATE_DONE
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|| iState == RTONCESTATE_DONE_CREATING_SEM
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|| iState == RTONCESTATE_DONE_HAVE_SEM ))
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return ASMAtomicUoReadS32(&pOnce->rc);
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return RTOnceSlow(pOnce, pfnOnce, NULL, pvUser);
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}
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/**
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* Execute pfnOnce once and register a termination clean-up callback.
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*
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* Serializes execution of the pfnOnce function, making sure it's
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* executed exactly once and that nobody returns from RTOnce before
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* it has executed successfully.
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*
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* @returns IPRT like status code returned by pfnOnce.
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*
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* @param pOnce Pointer to the execute once variable.
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* @param pfnOnce The function to executed once.
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* @param pfnCleanUp The function that will be doing the cleaning up.
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* @param pvUser The user parameter for pfnOnce.
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*/
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DECLINLINE(int) RTOnceEx(PRTONCE pOnce, PFNRTONCE pfnOnce, PFNRTONCECLEANUP pfnCleanUp, void *pvUser)
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{
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int32_t iState = ASMAtomicUoReadS32(&pOnce->iState);
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if (RT_LIKELY( iState == RTONCESTATE_DONE
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|| iState == RTONCESTATE_DONE_CREATING_SEM
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|| iState == RTONCESTATE_DONE_HAVE_SEM ))
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return ASMAtomicUoReadS32(&pOnce->rc);
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return RTOnceSlow(pOnce, pfnOnce, pfnCleanUp, pvUser);
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}
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/**
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* Resets an execute once variable.
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*
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* The caller is responsible for making sure there are no concurrent accesses to
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* the execute once variable.
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*
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* @param pOnce Pointer to the execute once variable.
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*/
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RTDECL(void) RTOnceReset(PRTONCE pOnce);
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/**
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* Check whether the execute once variable was successfullly initialized.
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*/
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DECLINLINE(bool) RTOnceWasInitialized(PRTONCE pOnce)
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{
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int32_t const iState = ASMAtomicUoReadS32(&pOnce->iState);
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int32_t const rc = ASMAtomicUoReadS32(&pOnce->rc);
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return RT_SUCCESS(rc)
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&& ( iState == RTONCESTATE_DONE
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|| iState == RTONCESTATE_DONE_CREATING_SEM
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|| iState == RTONCESTATE_DONE_HAVE_SEM);
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}
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/** @} */
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RT_C_DECLS_END
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#endif /* !IPRT_INCLUDED_once_h */
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