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
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
|
/*
* %CopyrightBegin%
*
* Copyright Ericsson AB 1997-2009. All Rights Reserved.
*
* The contents of this file are subject to the Erlang Public License,
* Version 1.1, (the "License"); you may not use this file except in
* compliance with the License. You should have received a copy of the
* Erlang Public License along with this software. If not, it can be
* retrieved online at http://www.erlang.org/.
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
* the License for the specific language governing rights and limitations
* under the License.
*
* %CopyrightEnd%
*
*/
/*
* common interface to some simple synchronisation primitives for
* internal use by ei.
*/
/* Note that these locks are NOT recursive on Win32 or Solaris,
* i.e. self-deadlock will occur if a thread tries to obtain a lock it
* is already holding. The primitives used on VxWorks are recursive however.
*/
#include "eidef.h"
#ifdef __WIN32__
#include <winsock2.h>
#include <windows.h>
#include <winbase.h>
#elif VXWORKS
#include <vxWorks.h>
#include <semLib.h>
#else /* unix */
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#endif /* platforms */
#include "ei_malloc.h"
#include "ei_locking.h"
#ifdef _REENTRANT
/*
* Create a new mutex object.
* Returns a pointer to the mutex if successful, NULL otherwise.
*/
ei_mutex_t *ei_mutex_create(void)
{
ei_mutex_t *l;
if ((l = ei_malloc(sizeof(*l))) == NULL) return NULL;
#ifdef __WIN32__
l->lock = CreateMutex(NULL,FALSE,NULL);
#elif VXWORKS
if (!(l->lock = semMCreate(SEM_DELETE_SAFE))) {
ei_free(l);
return NULL;
}
#else /* unix */
l->lock = ei_m_create();
#endif
return l;
}
/*
* Free a mutex and the structure asociated with it.
*
* This function attempts to obtain the mutex before releasing it;
* If nblock == 1 and the mutex was unavailable, the function will
* return failure and the mutex will not have been removed.
*
* If nblock == 0 the function will block until the mutex becomes
* available, at which time it will be removed and the function will
* succeed.
*
* returns 0 if the mutex is removed, -1 on failure (busy)
*/
int ei_mutex_free(ei_mutex_t *l, int nblock)
{
/* attempt to lock it first, to make sure it's really free */
if (ei_mutex_lock(l,nblock)) return -1; /* attempt failed */
/* we are now holding the lock */
#ifdef __WIN32__
CloseHandle(l->lock);
#elif VXWORKS
if (semDelete(l->lock) == ERROR) return -1;
#else /* unix */
ei_m_destroy(l->lock);
#endif
ei_free(l);
return 0;
}
/* Grab a mutex. If the mutex is not held by any other process the
* function returns so that the caller may enter a critical section.
* Processes subsequently wishing to obtain the lock will block
* until this process releases it.
*
* If the mutex is busy (held by some other process) and nblock == 0,
* the function will block until the mutex is freed by the process
* holding it, returning only when the mutex has been grabbed.
*
* If the mutex is busy and nblock != 0, the function will not block.
* Instead it will return -1 immediately, indicating that the
* operation failed.
* Returns 0 on success, -1 on failure.
*/
int ei_mutex_lock(ei_mutex_t *l, int nblock)
{
#ifdef __WIN32__
/* check valid values for timeout: is 0 ok? */
if (WaitForSingleObject(l->lock,(nblock? 0 : INFINITE)) != WAIT_OBJECT_0)
return -1;
#elif VXWORKS
if (semTake(l->lock,(nblock? NO_WAIT : WAIT_FOREVER)) == ERROR)
return -1;
#else /* unix */
if (nblock) {
if (ei_m_trylock(l->lock) < 0) return -1;
}
else ei_m_lock(l->lock);
#endif
return 0;
}
/* Release a mutex */
int ei_mutex_unlock(ei_mutex_t *l)
{
#ifdef __WIN32__
ReleaseMutex(l->lock);
#elif VXWORKS
semGive(l->lock);
#else /* unix */
ei_m_unlock(l->lock);
#endif
return 0;
}
#endif /* _REENTRANT */
|
