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