blob: 48bae9f6e631d552c7336c63b3b9e69594f375f0 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
|
/*
* pthread_rwlock_trywrlock.c
*
* Description:
* This translation unit implements read/write lock primitives.
*
* --------------------------------------------------------------------------
*
* Pthreads-win32 - POSIX Threads Library for Win32
* Copyright(C) 1998 John E. Bossom
* Copyright(C) 1999,2002 Pthreads-win32 contributors
*
* Contact Email: rpj@ise.canberra.edu.au
*
* The current list of contributors is contained
* in the file CONTRIBUTORS included with the source
* code distribution. The list can also be seen at the
* following World Wide Web location:
* http://sources.redhat.com/pthreads-win32/contributors.html
*
* This library 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 of the License, or (at your option) any later version.
*
* This library 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 library in the file COPYING.LIB;
* if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#include <errno.h>
#include <limits.h>
#include "pthread.h"
#include "implement.h"
int
pthread_rwlock_trywrlock(pthread_rwlock_t * rwlock)
{
int result, result1;
pthread_rwlock_t rwl;
if (rwlock == NULL || *rwlock == NULL)
{
return EINVAL;
}
/*
* We do a quick check to see if we need to do more work
* to initialise a static rwlock. We check
* again inside the guarded section of ptw32_rwlock_check_need_init()
* to avoid race conditions.
*/
if (*rwlock == PTHREAD_RWLOCK_INITIALIZER)
{
result = ptw32_rwlock_check_need_init(rwlock);
if (result != 0 && result != EBUSY)
{
return result;
}
}
rwl = *rwlock;
if (rwl->nMagic != PTW32_RWLOCK_MAGIC)
{
return EINVAL;
}
if ((result = pthread_mutex_trylock(&(rwl->mtxExclusiveAccess))) != 0)
{
return result;
}
if ((result = pthread_mutex_trylock(&(rwl->mtxSharedAccessCompleted))) != 0)
{
result1 = pthread_mutex_unlock(&(rwl->mtxExclusiveAccess));
return ((result1 != 0) ? result1 : result);
}
if (rwl->nExclusiveAccessCount == 0)
{
if (rwl->nCompletedSharedAccessCount > 0)
{
rwl->nSharedAccessCount -= rwl->nCompletedSharedAccessCount;
rwl->nCompletedSharedAccessCount = 0;
}
if (rwl->nSharedAccessCount > 0)
{
if ((result = pthread_mutex_unlock(&(rwl->mtxSharedAccessCompleted))) != 0)
{
(void) pthread_mutex_unlock(&(rwl->mtxExclusiveAccess));
return result;
}
if ((result = pthread_mutex_unlock(&(rwl->mtxExclusiveAccess))) == 0)
{
result = EBUSY;
}
}
else
{
rwl->nExclusiveAccessCount = 1;
}
}
else
{
result = EBUSY;
}
return result;
}
|
