common/misc/once.cpp

33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync/* $Id$ */
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync/** @file
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync * IPRT - Execute Once.
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync */
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync/*
a438caaf732f7839dc66b4f8dad672527845a003vboxsync * Copyright (C) 2007-2012 Oracle Corporation
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync *
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync * This file is part of VirtualBox Open Source Edition (OSE), as
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync * available from http://www.virtualbox.org. This file is free software;
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync * you can redistribute it and/or modify it under the terms of the GNU
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync * General Public License (GPL) as published by the Free Software
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync * Foundation, in version 2 as it comes in the "COPYING" file of the
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync *
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync * The contents of this file may alternatively be used under the terms
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync * of the Common Development and Distribution License Version 1.0
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync * VirtualBox OSE distribution, in which case the provisions of the
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync * CDDL are applicable instead of those of the GPL.
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync *
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync * You may elect to license modified versions of this file under the
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync * terms and conditions of either the GPL or the CDDL or both.
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync */
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync
aa4bcf0a4b2db3ac352b56a291d49cb8d4b66d32vboxsync
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync/*******************************************************************************
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync*   Header Files                                                               *
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync*******************************************************************************/
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync#include <iprt/once.h>
aa4bcf0a4b2db3ac352b56a291d49cb8d4b66d32vboxsync#include "internal/iprt.h"
aa4bcf0a4b2db3ac352b56a291d49cb8d4b66d32vboxsync
a438caaf732f7839dc66b4f8dad672527845a003vboxsync#include <iprt/asm.h>
a438caaf732f7839dc66b4f8dad672527845a003vboxsync#include <iprt/assert.h>
7ec1962ea423a724000021141f27198437f4c2dbvboxsync#ifdef IN_RING3
7ec1962ea423a724000021141f27198437f4c2dbvboxsync# include <iprt/critsect.h>
7ec1962ea423a724000021141f27198437f4c2dbvboxsync# define RTONCE_USE_CRITSECT_FOR_TERM
7ec1962ea423a724000021141f27198437f4c2dbvboxsync#elif defined(IN_RING0)
7ec1962ea423a724000021141f27198437f4c2dbvboxsync# include <iprt/spinlock.h>
7ec1962ea423a724000021141f27198437f4c2dbvboxsync# define RTONCE_USE_SPINLOCK_FOR_TERM
7ec1962ea423a724000021141f27198437f4c2dbvboxsync#else
7ec1962ea423a724000021141f27198437f4c2dbvboxsync# define RTONCE_NO_TERM
7ec1962ea423a724000021141f27198437f4c2dbvboxsync#endif
a438caaf732f7839dc66b4f8dad672527845a003vboxsync#include <iprt/err.h>
a438caaf732f7839dc66b4f8dad672527845a003vboxsync#include <iprt/initterm.h>
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync#include <iprt/semaphore.h>
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync#include <iprt/thread.h>
a438caaf732f7839dc66b4f8dad672527845a003vboxsync
a438caaf732f7839dc66b4f8dad672527845a003vboxsync
a438caaf732f7839dc66b4f8dad672527845a003vboxsync/*******************************************************************************
a438caaf732f7839dc66b4f8dad672527845a003vboxsync*   Global Variables                                                           *
a438caaf732f7839dc66b4f8dad672527845a003vboxsync*******************************************************************************/
7ec1962ea423a724000021141f27198437f4c2dbvboxsync#ifndef RTONCE_NO_TERM
a438caaf732f7839dc66b4f8dad672527845a003vboxsync/** For initializing the clean-up list code. */
a438caaf732f7839dc66b4f8dad672527845a003vboxsyncstatic RTONCE           g_OnceCleanUp = RTONCE_INITIALIZER;
7ec1962ea423a724000021141f27198437f4c2dbvboxsync/** Lock protecting the clean-up list. */
7ec1962ea423a724000021141f27198437f4c2dbvboxsync#ifdef RTONCE_USE_CRITSECT_FOR_TERM
a438caaf732f7839dc66b4f8dad672527845a003vboxsyncstatic RTCRITSECT       g_CleanUpCritSect;
7ec1962ea423a724000021141f27198437f4c2dbvboxsync#else
7ec1962ea423a724000021141f27198437f4c2dbvboxsyncstatic RTSEMFASTMUTEX   g_hCleanUpLock;
7ec1962ea423a724000021141f27198437f4c2dbvboxsync#endif
a438caaf732f7839dc66b4f8dad672527845a003vboxsync/** The clean-up list. */
a438caaf732f7839dc66b4f8dad672527845a003vboxsyncstatic RTLISTANCHOR     g_CleanUpList;
a438caaf732f7839dc66b4f8dad672527845a003vboxsync
7ec1962ea423a724000021141f27198437f4c2dbvboxsync/** Locks the clean-up list. */
7ec1962ea423a724000021141f27198437f4c2dbvboxsync#ifdef RTONCE_USE_CRITSECT_FOR_TERM
7ec1962ea423a724000021141f27198437f4c2dbvboxsync# define RTONCE_CLEANUP_LOCK()      RTCritSectEnter(&g_CleanUpCritSect)
7ec1962ea423a724000021141f27198437f4c2dbvboxsync#else
7ec1962ea423a724000021141f27198437f4c2dbvboxsync# define RTONCE_CLEANUP_LOCK()      RTSemFastMutexRequest(g_hCleanUpLock);
7ec1962ea423a724000021141f27198437f4c2dbvboxsync#endif
7ec1962ea423a724000021141f27198437f4c2dbvboxsync
7ec1962ea423a724000021141f27198437f4c2dbvboxsync/** Unlocks the clean-up list. */
7ec1962ea423a724000021141f27198437f4c2dbvboxsync#ifdef RTONCE_USE_CRITSECT_FOR_TERM
7ec1962ea423a724000021141f27198437f4c2dbvboxsync# define RTONCE_CLEANUP_UNLOCK()    RTCritSectLeave(&g_CleanUpCritSect);
7ec1962ea423a724000021141f27198437f4c2dbvboxsync#else
7ec1962ea423a724000021141f27198437f4c2dbvboxsync# define RTONCE_CLEANUP_UNLOCK()    RTSemFastMutexRelease(g_hCleanUpLock);
7ec1962ea423a724000021141f27198437f4c2dbvboxsync#endif
7ec1962ea423a724000021141f27198437f4c2dbvboxsync
7ec1962ea423a724000021141f27198437f4c2dbvboxsync
a438caaf732f7839dc66b4f8dad672527845a003vboxsync
a438caaf732f7839dc66b4f8dad672527845a003vboxsync/** @callback_method_impl{FNRTTERMCALLBACK} */
a438caaf732f7839dc66b4f8dad672527845a003vboxsyncstatic DECLCALLBACK(void) rtOnceTermCallback(RTTERMREASON enmReason, int32_t iStatus, void *pvUser)
a438caaf732f7839dc66b4f8dad672527845a003vboxsync{
a438caaf732f7839dc66b4f8dad672527845a003vboxsync    bool const fLazyCleanUpOk = RTTERMREASON_IS_LAZY_CLEANUP_OK(enmReason);
7ec1962ea423a724000021141f27198437f4c2dbvboxsync    RTONCE_CLEANUP_LOCK();      /* Potentially dangerous. */
a438caaf732f7839dc66b4f8dad672527845a003vboxsync
a438caaf732f7839dc66b4f8dad672527845a003vboxsync    PRTONCE pCur, pPrev;
a438caaf732f7839dc66b4f8dad672527845a003vboxsync    RTListForEachReverseSafe(&g_CleanUpList, pCur, pPrev, RTONCE, CleanUpNode)
a438caaf732f7839dc66b4f8dad672527845a003vboxsync    {
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        /*
a438caaf732f7839dc66b4f8dad672527845a003vboxsync         * Mostly reset it before doing the callback.
a438caaf732f7839dc66b4f8dad672527845a003vboxsync         *
a438caaf732f7839dc66b4f8dad672527845a003vboxsync         * Should probably introduce some new states here, but I'm not sure
a438caaf732f7839dc66b4f8dad672527845a003vboxsync         * it's really worth it at this point.
a438caaf732f7839dc66b4f8dad672527845a003vboxsync         */
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        PFNRTONCECLEANUP    pfnCleanUp    = pCur->pfnCleanUp;
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        void               *pvUserCleanUp = pCur->pvUser;
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        pCur->pvUser        = NULL;
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        pCur->pfnCleanUp    = NULL;
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        ASMAtomicWriteS32(&pCur->rc, VERR_WRONG_ORDER);
a438caaf732f7839dc66b4f8dad672527845a003vboxsync
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        pfnCleanUp(pvUserCleanUp, fLazyCleanUpOk);
a438caaf732f7839dc66b4f8dad672527845a003vboxsync
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        /*
a438caaf732f7839dc66b4f8dad672527845a003vboxsync         * Reset the reset of the state if we're being unloaded or smth.
a438caaf732f7839dc66b4f8dad672527845a003vboxsync         */
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        if (!fLazyCleanUpOk)
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        {
a438caaf732f7839dc66b4f8dad672527845a003vboxsync            ASMAtomicWriteS32(&pCur->rc, VERR_INTERNAL_ERROR);
a438caaf732f7839dc66b4f8dad672527845a003vboxsync            ASMAtomicWriteS32(&pCur->iState, RTONCESTATE_UNINITIALIZED);
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        }
a438caaf732f7839dc66b4f8dad672527845a003vboxsync    }
a438caaf732f7839dc66b4f8dad672527845a003vboxsync
7ec1962ea423a724000021141f27198437f4c2dbvboxsync    RTONCE_CLEANUP_UNLOCK();
7ec1962ea423a724000021141f27198437f4c2dbvboxsync
7ec1962ea423a724000021141f27198437f4c2dbvboxsync    /*
7ec1962ea423a724000021141f27198437f4c2dbvboxsync     * Reset our own structure and the critsect / mutex.
7ec1962ea423a724000021141f27198437f4c2dbvboxsync     */
7ec1962ea423a724000021141f27198437f4c2dbvboxsync    if (!fLazyCleanUpOk)
7ec1962ea423a724000021141f27198437f4c2dbvboxsync    {
7ec1962ea423a724000021141f27198437f4c2dbvboxsync# ifdef RTONCE_USE_CRITSECT_FOR_TERM
7ec1962ea423a724000021141f27198437f4c2dbvboxsync        RTCritSectDelete(&g_CleanUpCritSect);
7ec1962ea423a724000021141f27198437f4c2dbvboxsync# else
7ec1962ea423a724000021141f27198437f4c2dbvboxsync        RTSemFastMutexDestroy(g_hCleanUpLock);
7ec1962ea423a724000021141f27198437f4c2dbvboxsync        g_hCleanUpLock = NIL_RTSEMFASTMUTEX;
7ec1962ea423a724000021141f27198437f4c2dbvboxsync# endif
7ec1962ea423a724000021141f27198437f4c2dbvboxsync
7ec1962ea423a724000021141f27198437f4c2dbvboxsync        ASMAtomicWriteS32(&g_OnceCleanUp.rc, VERR_INTERNAL_ERROR);
7ec1962ea423a724000021141f27198437f4c2dbvboxsync        ASMAtomicWriteS32(&g_OnceCleanUp.iState, RTONCESTATE_UNINITIALIZED);
7ec1962ea423a724000021141f27198437f4c2dbvboxsync    }
7ec1962ea423a724000021141f27198437f4c2dbvboxsync
7ec1962ea423a724000021141f27198437f4c2dbvboxsync    NOREF(pvUser); NOREF(iStatus);
a438caaf732f7839dc66b4f8dad672527845a003vboxsync}
a438caaf732f7839dc66b4f8dad672527845a003vboxsync
a438caaf732f7839dc66b4f8dad672527845a003vboxsync
a438caaf732f7839dc66b4f8dad672527845a003vboxsync
a438caaf732f7839dc66b4f8dad672527845a003vboxsync/**
a438caaf732f7839dc66b4f8dad672527845a003vboxsync * Initializes the globals (using RTOnce).
a438caaf732f7839dc66b4f8dad672527845a003vboxsync *
a438caaf732f7839dc66b4f8dad672527845a003vboxsync * @returns IPRT status code
a438caaf732f7839dc66b4f8dad672527845a003vboxsync * @param   pvUser              Unused.
a438caaf732f7839dc66b4f8dad672527845a003vboxsync */
a438caaf732f7839dc66b4f8dad672527845a003vboxsyncstatic DECLCALLBACK(int32_t) rtOnceInitCleanUp(void *pvUser)
a438caaf732f7839dc66b4f8dad672527845a003vboxsync{
a438caaf732f7839dc66b4f8dad672527845a003vboxsync    NOREF(pvUser);
a438caaf732f7839dc66b4f8dad672527845a003vboxsync    RTListInit(&g_CleanUpList);
7ec1962ea423a724000021141f27198437f4c2dbvboxsync# ifdef RTONCE_USE_CRITSECT_FOR_TERM
a438caaf732f7839dc66b4f8dad672527845a003vboxsync    int rc = RTCritSectInit(&g_CleanUpCritSect);
7ec1962ea423a724000021141f27198437f4c2dbvboxsync# else
7ec1962ea423a724000021141f27198437f4c2dbvboxsync    int rc = RTSemFastMutexCreate(&g_hCleanUpLock);
7ec1962ea423a724000021141f27198437f4c2dbvboxsync# endif
a438caaf732f7839dc66b4f8dad672527845a003vboxsync    if (RT_SUCCESS(rc))
a438caaf732f7839dc66b4f8dad672527845a003vboxsync    {
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        rc = RTTermRegisterCallback(rtOnceTermCallback, NULL);
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        if (RT_SUCCESS(rc))
a438caaf732f7839dc66b4f8dad672527845a003vboxsync            return rc;
a438caaf732f7839dc66b4f8dad672527845a003vboxsync
7ec1962ea423a724000021141f27198437f4c2dbvboxsync# ifdef RTONCE_USE_CRITSECT_FOR_TERM
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        RTCritSectDelete(&g_CleanUpCritSect);
7ec1962ea423a724000021141f27198437f4c2dbvboxsync# else
7ec1962ea423a724000021141f27198437f4c2dbvboxsync        RTSemFastMutexDestroy(g_hCleanUpLock);
7ec1962ea423a724000021141f27198437f4c2dbvboxsync        g_hCleanUpLock = NIL_RTSEMFASTMUTEX;
7ec1962ea423a724000021141f27198437f4c2dbvboxsync# endif
a438caaf732f7839dc66b4f8dad672527845a003vboxsync    }
a438caaf732f7839dc66b4f8dad672527845a003vboxsync    return rc;
a438caaf732f7839dc66b4f8dad672527845a003vboxsync}
a438caaf732f7839dc66b4f8dad672527845a003vboxsync
7ec1962ea423a724000021141f27198437f4c2dbvboxsync#endif /* !RTONCE_NO_TERM */
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync/**
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync * The state loop of the other threads.
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync *
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync * @returns VINF_SUCCESS when everything went smoothly. IPRT status code if we
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync *          encountered trouble.
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync * @param   pOnce           The execute once structure.
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync * @param   phEvtM          Where to store the semaphore handle so the caller
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync *                          can do the cleaning up for us.
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync */
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsyncstatic int rtOnceOtherThread(PRTONCE pOnce, PRTSEMEVENTMULTI phEvtM)
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync{
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync    uint32_t cYields = 0;
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync    for (;;)
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync    {
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync        int32_t iState = ASMAtomicReadS32(&pOnce->iState);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync        switch (iState)
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync        {
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            /*
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync             * No semaphore, try create one.
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync             */
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            case RTONCESTATE_BUSY_NO_SEM:
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                if (ASMAtomicCmpXchgS32(&pOnce->iState, RTONCESTATE_BUSY_CREATING_SEM, RTONCESTATE_BUSY_NO_SEM))
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                {
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                    int rc = RTSemEventMultiCreate(phEvtM);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                    if (RT_SUCCESS(rc))
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                    {
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                        ASMAtomicWriteHandle(&pOnce->hEventMulti, *phEvtM);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                        int32_t cRefs = ASMAtomicIncS32(&pOnce->cEventRefs); Assert(cRefs == 1); NOREF(cRefs);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                        if (!ASMAtomicCmpXchgS32(&pOnce->iState, RTONCESTATE_BUSY_HAVE_SEM, RTONCESTATE_BUSY_CREATING_SEM))
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                        {
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                            /* Too slow. */
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                            AssertReturn(ASMAtomicCmpXchgS32(&pOnce->iState, RTONCESTATE_DONE, RTONCESTATE_DONE_CREATING_SEM)
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                                         , VERR_INTERNAL_ERROR_5);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                            ASMAtomicWriteHandle(&pOnce->hEventMulti, NIL_RTSEMEVENTMULTI);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                            cRefs = ASMAtomicDecS32(&pOnce->cEventRefs); Assert(cRefs == 0);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                            RTSemEventMultiDestroy(*phEvtM);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                            *phEvtM = NIL_RTSEMEVENTMULTI;
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                        }
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                    }
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                    else
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                    {
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                        AssertReturn(   ASMAtomicCmpXchgS32(&pOnce->iState, RTONCESTATE_BUSY_SPIN, RTONCESTATE_BUSY_CREATING_SEM)
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                                     || ASMAtomicCmpXchgS32(&pOnce->iState, RTONCESTATE_DONE,      RTONCESTATE_DONE_CREATING_SEM)
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                                     , VERR_INTERNAL_ERROR_4);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                        *phEvtM = NIL_RTSEMEVENTMULTI;
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                    }
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                }
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                break;
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            /*
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync             * This isn't nice, but it's the easy way out.
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync             */
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            case RTONCESTATE_BUSY_CREATING_SEM:
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            case RTONCESTATE_BUSY_SPIN:
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                cYields++;
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                if (!(++cYields % 8))
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                    RTThreadSleep(1);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                else
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                    RTThreadYield();
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                break;
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            /*
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync             * There is a semaphore, try wait on it.
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync             *
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync             * We continue waiting after reaching DONE_HAVE_SEM if we
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync             * already got the semaphore to avoid racing the first thread.
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync             */
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            case RTONCESTATE_DONE_HAVE_SEM:
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                if (*phEvtM == NIL_RTSEMEVENTMULTI)
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                    return VINF_SUCCESS;
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                /* fall thru */
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            case RTONCESTATE_BUSY_HAVE_SEM:
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            {
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                /*
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                 * Grab the semaphore if we haven't got it yet.
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                 * We must take care not to increment the counter if it
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                 * is 0.  This may happen if we're racing a state change.
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                 */
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                if (*phEvtM == NIL_RTSEMEVENTMULTI)
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                {
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                    int32_t cEventRefs = ASMAtomicUoReadS32(&pOnce->cEventRefs);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                    while (   cEventRefs > 0
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                           && ASMAtomicUoReadS32(&pOnce->iState) == RTONCESTATE_BUSY_HAVE_SEM)
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                    {
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                        if (ASMAtomicCmpXchgExS32(&pOnce->cEventRefs, cEventRefs + 1, cEventRefs, &cEventRefs))
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                            break;
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                        ASMNopPause();
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                    }
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                    if (cEventRefs <= 0)
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                        break;
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                    ASMAtomicReadHandle(&pOnce->hEventMulti, phEvtM);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                    AssertReturn(*phEvtM != NIL_RTSEMEVENTMULTI, VERR_INTERNAL_ERROR_2);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                }
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                /*
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                 * We've got a sempahore, do the actual waiting.
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                 */
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                do
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                    RTSemEventMultiWaitNoResume(*phEvtM, RT_INDEFINITE_WAIT);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                while (ASMAtomicReadS32(&pOnce->iState) == RTONCESTATE_BUSY_HAVE_SEM);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                break;
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            }
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            case RTONCESTATE_DONE_CREATING_SEM:
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            case RTONCESTATE_DONE:
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                return VINF_SUCCESS;
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            default:
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                AssertMsgFailedReturn(("%d\n", iState), VERR_INTERNAL_ERROR_3);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync        }
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync    }
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync}
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync
a438caaf732f7839dc66b4f8dad672527845a003vboxsyncRTDECL(int) RTOnceSlow(PRTONCE pOnce, PFNRTONCE pfnOnce, PFNRTONCECLEANUP pfnCleanUp, void *pvUser)
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync{
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync    /*
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync     * Validate input (strict builds only).
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync     */
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync    AssertPtr(pOnce);
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync    AssertPtr(pfnOnce);
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync    /*
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync     * Deal with the 'initialized' case first
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync     */
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync    int32_t iState = ASMAtomicUoReadS32(&pOnce->iState);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync    if (RT_LIKELY(   iState == RTONCESTATE_DONE
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                  || iState == RTONCESTATE_DONE_CREATING_SEM
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                  || iState == RTONCESTATE_DONE_HAVE_SEM
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                 ))
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync        return ASMAtomicUoReadS32(&pOnce->rc);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync    AssertReturn(   iState == RTONCESTATE_UNINITIALIZED
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                 || iState == RTONCESTATE_BUSY_NO_SEM
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                 || iState == RTONCESTATE_BUSY_SPIN
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                 || iState == RTONCESTATE_BUSY_CREATING_SEM
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                 || iState == RTONCESTATE_BUSY_HAVE_SEM
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                 , VERR_INTERNAL_ERROR);
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync
7ec1962ea423a724000021141f27198437f4c2dbvboxsync#ifdef RTONCE_NO_TERM
445eda8e100192896ea4a8273d42d29af767364evboxsync    AssertReturn(!pfnCleanUp, VERR_NOT_SUPPORTED);
7ec1962ea423a724000021141f27198437f4c2dbvboxsync#else /* !RTONCE_NO_TERM */
a438caaf732f7839dc66b4f8dad672527845a003vboxsync
a438caaf732f7839dc66b4f8dad672527845a003vboxsync    /*
a438caaf732f7839dc66b4f8dad672527845a003vboxsync     * Make sure our clean-up bits are working if needed later.
a438caaf732f7839dc66b4f8dad672527845a003vboxsync     */
a438caaf732f7839dc66b4f8dad672527845a003vboxsync    if (pfnCleanUp)
a438caaf732f7839dc66b4f8dad672527845a003vboxsync    {
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        int rc = RTOnce(&g_OnceCleanUp, rtOnceInitCleanUp, NULL);
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        if (RT_FAILURE(rc))
a438caaf732f7839dc66b4f8dad672527845a003vboxsync            return rc;
a438caaf732f7839dc66b4f8dad672527845a003vboxsync    }
7ec1962ea423a724000021141f27198437f4c2dbvboxsync#endif /* !RTONCE_NO_TERM */
a438caaf732f7839dc66b4f8dad672527845a003vboxsync
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync    /*
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync     * Do we initialize it?
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync     */
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync    int32_t rcOnce;
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync    if (   iState == RTONCESTATE_UNINITIALIZED
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync        && ASMAtomicCmpXchgS32(&pOnce->iState, RTONCESTATE_BUSY_NO_SEM, RTONCESTATE_UNINITIALIZED))
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync    {
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync        /*
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync         * Yes, so do the execute once stuff.
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync         */
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        rcOnce = pfnOnce(pvUser);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync        ASMAtomicWriteS32(&pOnce->rc, rcOnce);
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync
7ec1962ea423a724000021141f27198437f4c2dbvboxsync#ifndef RTONCE_NO_TERM
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        /*
a438caaf732f7839dc66b4f8dad672527845a003vboxsync         * Register clean-up if requested and we were successful.
a438caaf732f7839dc66b4f8dad672527845a003vboxsync         */
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        if (pfnCleanUp && RT_SUCCESS(rcOnce))
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        {
7ec1962ea423a724000021141f27198437f4c2dbvboxsync            RTONCE_CLEANUP_LOCK();
7ec1962ea423a724000021141f27198437f4c2dbvboxsync
a438caaf732f7839dc66b4f8dad672527845a003vboxsync            pOnce->pfnCleanUp = pfnCleanUp;
a438caaf732f7839dc66b4f8dad672527845a003vboxsync            pOnce->pvUser     = pvUser;
a438caaf732f7839dc66b4f8dad672527845a003vboxsync            RTListAppend(&g_CleanUpList, &pOnce->CleanUpNode);
7ec1962ea423a724000021141f27198437f4c2dbvboxsync
7ec1962ea423a724000021141f27198437f4c2dbvboxsync            RTONCE_CLEANUP_UNLOCK();
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        }
7ec1962ea423a724000021141f27198437f4c2dbvboxsync#endif /* !RTONCE_NO_TERM */
a438caaf732f7839dc66b4f8dad672527845a003vboxsync
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync        /*
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync         * If there is a sempahore to signal, we're in for some extra work here.
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync         */
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync        if (   !ASMAtomicCmpXchgS32(&pOnce->iState, RTONCESTATE_DONE,              RTONCESTATE_BUSY_NO_SEM)
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            && !ASMAtomicCmpXchgS32(&pOnce->iState, RTONCESTATE_DONE,              RTONCESTATE_BUSY_SPIN)
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            && !ASMAtomicCmpXchgS32(&pOnce->iState, RTONCESTATE_DONE_CREATING_SEM, RTONCESTATE_BUSY_CREATING_SEM)
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync           )
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync        {
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            /* Grab the sempahore by switching to 'DONE_HAVE_SEM' before reaching 'DONE'. */
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            AssertReturn(ASMAtomicCmpXchgS32(&pOnce->iState, RTONCESTATE_DONE_HAVE_SEM, RTONCESTATE_BUSY_HAVE_SEM),
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                         VERR_INTERNAL_ERROR_2);
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            int32_t cRefs = ASMAtomicIncS32(&pOnce->cEventRefs);
de77073de5b4af1b1b5bce23357daea25c1c4d6fvboxsync            Assert(cRefs > 1); NOREF(cRefs);
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            RTSEMEVENTMULTI hEvtM;
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            ASMAtomicReadHandle(&pOnce->hEventMulti, &hEvtM);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            Assert(hEvtM != NIL_RTSEMEVENTMULTI);
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            ASMAtomicWriteS32(&pOnce->iState, RTONCESTATE_DONE);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            /* Signal it and return. */
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            RTSemEventMultiSignal(hEvtM);
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync        }
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync    }
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync    else
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync    {
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync        /*
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync         * Wait for the first thread to complete.  Delegate this to a helper
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync         * function to simplify cleanup and keep things a bit shorter.
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync         */
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync        RTSEMEVENTMULTI hEvtM = NIL_RTSEMEVENTMULTI;
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync        rcOnce = rtOnceOtherThread(pOnce, &hEvtM);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync        if (hEvtM != NIL_RTSEMEVENTMULTI)
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync        {
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            if (ASMAtomicDecS32(&pOnce->cEventRefs) == 0)
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync            {
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                bool fRc;
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                ASMAtomicCmpXchgHandle(&pOnce->hEventMulti, NIL_RTSEMEVENTMULTI, hEvtM, fRc);           Assert(fRc);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                fRc = ASMAtomicCmpXchgS32(&pOnce->iState, RTONCESTATE_DONE, RTONCESTATE_DONE_HAVE_SEM); Assert(fRc);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync                RTSemEventMultiDestroy(hEvtM);
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync            }
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync        }
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync        if (RT_SUCCESS(rcOnce))
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync            rcOnce = ASMAtomicUoReadS32(&pOnce->rc);
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync    }
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync    return rcOnce;
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync}
e420253a89a6e07613f49cfd9a1db9e217039575vboxsyncRT_EXPORT_SYMBOL(RTOnceSlow);
33b0e5fd502b10034575ffa7c8a30c6816222ce2vboxsync
6e59cff536e8de93f15fa1fb6b46d0ee01e06829vboxsync
6e59cff536e8de93f15fa1fb6b46d0ee01e06829vboxsyncRTDECL(void) RTOnceReset(PRTONCE pOnce)
6e59cff536e8de93f15fa1fb6b46d0ee01e06829vboxsync{
6e59cff536e8de93f15fa1fb6b46d0ee01e06829vboxsync    /* Cannot be done while busy! */
6e59cff536e8de93f15fa1fb6b46d0ee01e06829vboxsync    AssertPtr(pOnce);
6e59cff536e8de93f15fa1fb6b46d0ee01e06829vboxsync    Assert(pOnce->hEventMulti == NIL_RTSEMEVENTMULTI);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync    int32_t iState = ASMAtomicUoReadS32(&pOnce->iState);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync    AssertMsg(   iState == RTONCESTATE_DONE
c2be0925a1da56d9e86499771017332e73bf3fabvboxsync              || iState == RTONCESTATE_UNINITIALIZED,
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync              ("%d\n", iState));
de77073de5b4af1b1b5bce23357daea25c1c4d6fvboxsync    NOREF(iState);
6e59cff536e8de93f15fa1fb6b46d0ee01e06829vboxsync
7ec1962ea423a724000021141f27198437f4c2dbvboxsync#ifndef RTONCE_NO_TERM
a438caaf732f7839dc66b4f8dad672527845a003vboxsync    /* Unregister clean-up. */
a438caaf732f7839dc66b4f8dad672527845a003vboxsync    if (pOnce->pfnCleanUp)
a438caaf732f7839dc66b4f8dad672527845a003vboxsync    {
7ec1962ea423a724000021141f27198437f4c2dbvboxsync        RTONCE_CLEANUP_LOCK();
7ec1962ea423a724000021141f27198437f4c2dbvboxsync
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        RTListNodeRemove(&pOnce->CleanUpNode);
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        pOnce->pfnCleanUp = NULL;
a438caaf732f7839dc66b4f8dad672527845a003vboxsync        pOnce->pvUser     = NULL;
7ec1962ea423a724000021141f27198437f4c2dbvboxsync
7ec1962ea423a724000021141f27198437f4c2dbvboxsync        RTONCE_CLEANUP_UNLOCK();
a438caaf732f7839dc66b4f8dad672527845a003vboxsync    }
7ec1962ea423a724000021141f27198437f4c2dbvboxsync#endif /* !RTONCE_NO_TERM */
a438caaf732f7839dc66b4f8dad672527845a003vboxsync
6e59cff536e8de93f15fa1fb6b46d0ee01e06829vboxsync    /* Do the same as RTONCE_INITIALIZER does. */
6e59cff536e8de93f15fa1fb6b46d0ee01e06829vboxsync    ASMAtomicWriteS32(&pOnce->rc, VERR_INTERNAL_ERROR);
96ae2df030763cee874d3f5ac0be07cd1f793281vboxsync    ASMAtomicWriteS32(&pOnce->iState, RTONCESTATE_UNINITIALIZED);
6e59cff536e8de93f15fa1fb6b46d0ee01e06829vboxsync}
aa4bcf0a4b2db3ac352b56a291d49cb8d4b66d32vboxsyncRT_EXPORT_SYMBOL(RTOnceReset);
6e59cff536e8de93f15fa1fb6b46d0ee01e06829vboxsync