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/* Once-only control (native Windows implementation).
Copyright (C) 2005-2020 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, see <https://www.gnu.org/licenses/>. */
/* Written by Bruno Haible <bruno@clisp.org>, 2005.
Based on GCC's gthr-win32.h. */
#include <config.h>
/* Specification. */
#include "windows-once.h"
#include <stdlib.h>
void
glwthread_once (glwthread_once_t *once_control, void (*initfunction) (void))
{
if (once_control->inited <= 0)
{
if (InterlockedIncrement (&once_control->started) == 0)
{
/* This thread is the first one to come to this once_control. */
InitializeCriticalSection (&once_control->lock);
EnterCriticalSection (&once_control->lock);
once_control->inited = 0;
initfunction ();
once_control->inited = 1;
LeaveCriticalSection (&once_control->lock);
}
else
{
/* Don't let once_control->started grow and wrap around. */
InterlockedDecrement (&once_control->started);
/* Some other thread has already started the initialization.
Yield the CPU while waiting for the other thread to finish
initializing and taking the lock. */
while (once_control->inited < 0)
Sleep (0);
if (once_control->inited <= 0)
{
/* Take the lock. This blocks until the other thread has
finished calling the initfunction. */
EnterCriticalSection (&once_control->lock);
LeaveCriticalSection (&once_control->lock);
if (!(once_control->inited > 0))
abort ();
}
}
}
}
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