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authorJörg Frings-Fürst <debian@jff.email>2022-01-08 11:53:52 +0100
committerJörg Frings-Fürst <debian@jff.email>2022-01-08 11:53:52 +0100
commitfa838e76139763f902c7d27cb9e1d393ed6a15e4 (patch)
tree7d0ae09775ea950056193eaa2ca93844299d46f1 /lib/windows-once.c
parentc78359d9542c86b972aac373efcf7bc7a8a560e5 (diff)
parent2959e59fab3bab834368adefd90bd4b1b094366b (diff)
Merge branch 'feature/upstream' into develop
Diffstat (limited to 'lib/windows-once.c')
-rw-r--r--lib/windows-once.c62
1 files changed, 62 insertions, 0 deletions
diff --git a/lib/windows-once.c b/lib/windows-once.c
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+++ b/lib/windows-once.c
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+/* Once-only control (native Windows implementation).
+ Copyright (C) 2005-2022 Free Software Foundation, Inc.
+
+ This file is free software: you can redistribute it and/or modify
+ it under the terms of the GNU Lesser General Public License as
+ published by the Free Software Foundation; either version 2.1 of the
+ License, or (at your option) any later version.
+
+ This file 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 Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser 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 ();
+ }
+ }
+ }
+}