once.cpp revision e64031e20c39650a7bc902a3e1aba613b9415dee
/* $Id$ */
/** @file
* IPRT - Execute Once.
*/
/*
* Copyright (C) 2007 Oracle Corporation
*
* This file is part of VirtualBox Open Source Edition (OSE), as
* available from http://www.virtualbox.org. This file is free software;
* General Public License (GPL) as published by the Free Software
* Foundation, in version 2 as it comes in the "COPYING" file of the
* VirtualBox OSE distribution. VirtualBox OSE is distributed in the
* hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
*
* The contents of this file may alternatively be used under the terms
* of the Common Development and Distribution License Version 1.0
* (CDDL) only, as it comes in the "COPYING.CDDL" file of the
* VirtualBox OSE distribution, in which case the provisions of the
* CDDL are applicable instead of those of the GPL.
*
* You may elect to license modified versions of this file under the
* terms and conditions of either the GPL or the CDDL or both.
*/
/*******************************************************************************
* Header Files *
*******************************************************************************/
#include <iprt/semaphore.h>
{
/*
* Validate input (strict builds only).
*/
/*
* Deal with the 'initialized' case first
*/
/*
* Do we initialize it?
*/
if (iState == -1)
{
if (RT_FAILURE(rc))
{
/* do the execute once stuff. */
/* set the return code, change the state and signal any waiters. */
if (hEventMulti != NIL_RTSEMEVENTMULTI)
/* last guy destroys the semaphore. */
else
}
if (hEventMulti != NIL_RTSEMEVENTMULTI)
}
/*
* Wait for it to finish initializing.
*/
{
int i = 0;
{
bool fYieldSleep = true;
/*
* Take care not to increment the counter if it's 0, that indicates
* that RTONCE::hEventMulti isn't valid either because it's not set
* yet, or because it's being destroyed.
*/
while ( cEventRefs > 0
if (cEventRefs > 1)
{
/*
* The hEventMulti might be NIL for two reasons, see above in
*/
if (hEventMulti != NIL_RTSEMEVENTMULTI)
{
fYieldSleep = false;
}
/*
* Last thread cleans up.
*/
{
if (hEventMulti != NIL_RTSEMEVENTMULTI)
}
}
/*
* If we didn't block, yield or sleep for a bit.
*
* The sleep is essential to prevent higher priority threads from spinning wildly
* and preventing a lower priority thread from completing the pfnOnce operation
* in a timely manner.
*/
if (fYieldSleep)
{
break;
if (!(++i % 8) )
RTThreadSleep(1);
else
}
}
}
/*
* Finally, return the status code from the execute once function.
*/
}
{
/* Cannot be done while busy! */
/* Do the same as RTONCE_INITIALIZER does. */
}