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
|
/*
* ptw32_semwait.c
*
* Description:
* This translation unit implements mutual exclusion (mutex) primitives.
*
* --------------------------------------------------------------------------
*
* Pthreads4w - POSIX Threads Library for Win32
* Copyright(C) 1998 John E. Bossom
* Copyright(C) 1999-2018, Pthreads4w contributors
*
* Homepage: https://sourceforge.net/projects/pthreads4w/
*
* 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:
* https://sourceforge.net/p/pthreads4w/wiki/Contributors/
*
* This file is part of Pthreads4w.
*
* Pthreads4w is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Pthreads4w 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Pthreads4w. If not, see <http://www.gnu.org/licenses/>. *
*/
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#if !defined(_UWIN)
/*# include <process.h> */
#endif
#include "pthread.h"
#include "implement.h"
int
ptw32_semwait (sem_t * sem)
/*
* ------------------------------------------------------
* DESCRIPTION
* This function waits on a POSIX semaphore. If the
* semaphore value is greater than zero, it decreases
* its value by one. If the semaphore value is zero, then
* the calling thread (or process) is blocked until it can
* successfully decrease the value.
*
* Unlike sem_wait(), this routine is non-cancelable.
*
* RESULTS
* 0 successfully decreased semaphore,
* -1 failed, error in errno.
* ERRNO
* EINVAL 'sem' is not a valid semaphore,
* ENOSYS semaphores are not supported,
* EINTR the function was interrupted by a signal,
* EDEADLK a deadlock condition was detected.
*
* ------------------------------------------------------
*/
{
ptw32_mcs_local_node_t node;
int v;
int result = 0;
sem_t s = *sem;
ptw32_mcs_lock_acquire(&s->lock, &node);
v = --s->value;
ptw32_mcs_lock_release(&node);
if (v < 0)
{
/* Must wait */
if (WaitForSingleObject (s->sem, INFINITE) == WAIT_OBJECT_0)
{
#if defined(NEED_SEM)
ptw32_mcs_lock_acquire(&s->lock, &node);
if (s->leftToUnblock > 0)
{
--s->leftToUnblock;
SetEvent(s->sem);
}
ptw32_mcs_lock_release(&node);
#endif
return 0;
}
}
else
{
return 0;
}
if (result != 0)
{
PTW32_SET_ERRNO(result);
return -1;
}
return 0;
} /* ptw32_semwait */
|
