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c0c3707f | 1 | /* Plain mutexes (native Windows implementation). |
5df4cba6 | 2 | Copyright (C) 2005-2020 Free Software Foundation, Inc. |
c0c3707f CB |
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-mutex.h" | |
24 | ||
25 | #include <errno.h> | |
26 | ||
27 | void | |
28 | glwthread_mutex_init (glwthread_mutex_t *mutex) | |
29 | { | |
30 | InitializeCriticalSection (&mutex->lock); | |
31 | mutex->guard.done = 1; | |
32 | } | |
33 | ||
34 | int | |
35 | glwthread_mutex_lock (glwthread_mutex_t *mutex) | |
36 | { | |
37 | if (!mutex->guard.done) | |
38 | { | |
39 | if (InterlockedIncrement (&mutex->guard.started) == 0) | |
40 | /* This thread is the first one to need this mutex. Initialize it. */ | |
41 | glwthread_mutex_init (mutex); | |
42 | else | |
43 | { | |
44 | /* Don't let mutex->guard.started grow and wrap around. */ | |
45 | InterlockedDecrement (&mutex->guard.started); | |
46 | /* Yield the CPU while waiting for another thread to finish | |
47 | initializing this mutex. */ | |
48 | while (!mutex->guard.done) | |
49 | Sleep (0); | |
50 | } | |
51 | } | |
52 | EnterCriticalSection (&mutex->lock); | |
53 | return 0; | |
54 | } | |
55 | ||
56 | int | |
57 | glwthread_mutex_trylock (glwthread_mutex_t *mutex) | |
58 | { | |
59 | if (!mutex->guard.done) | |
60 | { | |
61 | if (InterlockedIncrement (&mutex->guard.started) == 0) | |
62 | /* This thread is the first one to need this mutex. Initialize it. */ | |
63 | glwthread_mutex_init (mutex); | |
64 | else | |
65 | { | |
66 | /* Don't let mutex->guard.started grow and wrap around. */ | |
67 | InterlockedDecrement (&mutex->guard.started); | |
68 | /* Let another thread finish initializing this mutex, and let it also | |
69 | lock this mutex. */ | |
70 | return EBUSY; | |
71 | } | |
72 | } | |
73 | if (!TryEnterCriticalSection (&mutex->lock)) | |
74 | return EBUSY; | |
75 | return 0; | |
76 | } | |
77 | ||
78 | int | |
79 | glwthread_mutex_unlock (glwthread_mutex_t *mutex) | |
80 | { | |
81 | if (!mutex->guard.done) | |
82 | return EINVAL; | |
83 | LeaveCriticalSection (&mutex->lock); | |
84 | return 0; | |
85 | } | |
86 | ||
87 | int | |
88 | glwthread_mutex_destroy (glwthread_mutex_t *mutex) | |
89 | { | |
90 | if (!mutex->guard.done) | |
91 | return EINVAL; | |
92 | DeleteCriticalSection (&mutex->lock); | |
93 | mutex->guard.done = 0; | |
94 | return 0; | |
95 | } |