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c0c3707f | 1 | /* Read-write locks (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 | #ifndef _WINDOWS_RWLOCK_H | |
21 | #define _WINDOWS_RWLOCK_H | |
22 | ||
23 | #define WIN32_LEAN_AND_MEAN /* avoid including junk */ | |
24 | #include <windows.h> | |
25 | ||
26 | #include "windows-initguard.h" | |
27 | ||
28 | /* It is impossible to implement read-write locks using plain locks, without | |
29 | introducing an extra thread dedicated to managing read-write locks. | |
30 | Therefore here we need to use the low-level Event type. */ | |
31 | ||
32 | typedef struct | |
33 | { | |
34 | HANDLE *array; /* array of waiting threads, each represented by an event */ | |
35 | unsigned int count; /* number of waiting threads */ | |
36 | unsigned int alloc; /* length of allocated array */ | |
37 | unsigned int offset; /* index of first waiting thread in array */ | |
38 | } | |
39 | glwthread_carray_waitqueue_t; | |
40 | typedef struct | |
41 | { | |
42 | glwthread_initguard_t guard; /* protects the initialization */ | |
43 | CRITICAL_SECTION lock; /* protects the remaining fields */ | |
44 | glwthread_carray_waitqueue_t waiting_readers; /* waiting readers */ | |
45 | glwthread_carray_waitqueue_t waiting_writers; /* waiting writers */ | |
46 | int runcount; /* number of readers running, or -1 when a writer runs */ | |
47 | } | |
48 | glwthread_rwlock_t; | |
49 | ||
50 | #define GLWTHREAD_RWLOCK_INIT { GLWTHREAD_INITGUARD_INIT } | |
51 | ||
52 | #ifdef __cplusplus | |
53 | extern "C" { | |
54 | #endif | |
55 | ||
56 | extern void glwthread_rwlock_init (glwthread_rwlock_t *lock); | |
57 | extern int glwthread_rwlock_rdlock (glwthread_rwlock_t *lock); | |
58 | extern int glwthread_rwlock_wrlock (glwthread_rwlock_t *lock); | |
59 | extern int glwthread_rwlock_tryrdlock (glwthread_rwlock_t *lock); | |
60 | extern int glwthread_rwlock_trywrlock (glwthread_rwlock_t *lock); | |
61 | extern int glwthread_rwlock_unlock (glwthread_rwlock_t *lock); | |
62 | extern int glwthread_rwlock_destroy (glwthread_rwlock_t *lock); | |
63 | ||
64 | #ifdef __cplusplus | |
65 | } | |
66 | #endif | |
67 | ||
68 | #endif /* _WINDOWS_RWLOCK_H */ |