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1 | /* Once-only control (native Windows implementation). |
2 | Copyright (C) 2005-2019 Free Software Foundation, Inc. | |
3 | ||
4 | This program is free software; you can redistribute it and/or modify | |
5 | it under the terms of the GNU General Public License as published by | |
6 | the Free Software Foundation; either version 3, or (at your option) | |
7 | any later version. | |
8 | ||
9 | This program is distributed in the hope that it will be useful, | |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | GNU General Public License for more details. | |
13 | ||
14 | You should have received a copy of the GNU General Public License | |
15 | along with this program; if not, see <https://www.gnu.org/licenses/>. */ | |
16 | ||
17 | /* Written by Bruno Haible <bruno@clisp.org>, 2005. | |
18 | Based on GCC's gthr-win32.h. */ | |
19 | ||
20 | #include <config.h> | |
21 | ||
22 | /* Specification. */ | |
23 | #include "windows-once.h" | |
24 | ||
25 | #include <stdlib.h> | |
26 | ||
27 | void | |
28 | glwthread_once (glwthread_once_t *once_control, void (*initfunction) (void)) | |
29 | { | |
30 | if (once_control->inited <= 0) | |
31 | { | |
32 | if (InterlockedIncrement (&once_control->started) == 0) | |
33 | { | |
34 | /* This thread is the first one to come to this once_control. */ | |
35 | InitializeCriticalSection (&once_control->lock); | |
36 | EnterCriticalSection (&once_control->lock); | |
37 | once_control->inited = 0; | |
38 | initfunction (); | |
39 | once_control->inited = 1; | |
40 | LeaveCriticalSection (&once_control->lock); | |
41 | } | |
42 | else | |
43 | { | |
44 | /* Don't let once_control->started grow and wrap around. */ | |
45 | InterlockedDecrement (&once_control->started); | |
46 | /* Some other thread has already started the initialization. | |
47 | Yield the CPU while waiting for the other thread to finish | |
48 | initializing and taking the lock. */ | |
49 | while (once_control->inited < 0) | |
50 | Sleep (0); | |
51 | if (once_control->inited <= 0) | |
52 | { | |
53 | /* Take the lock. This blocks until the other thread has | |
54 | finished calling the initfunction. */ | |
55 | EnterCriticalSection (&once_control->lock); | |
56 | LeaveCriticalSection (&once_control->lock); | |
57 | if (!(once_control->inited > 0)) | |
58 | abort (); | |
59 | } | |
60 | } | |
61 | } | |
62 | } |