src/thread/linux/SDL_sysmutex.c
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FUNCTIONS
This source file includes following functions.
- SDL_CreateMutex
- SDL_DestroyMutex
- SDL_mutexP
- SDL_mutexV
1 /*
2 SDL - Simple DirectMedia Layer
3 Copyright (C) 1997, 1998, 1999, 2000, 2001 Sam Lantinga
4
5 This library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Library General Public
7 License as published by the Free Software Foundation; either
8 version 2 of the License, or (at your option) any later version.
9
10 This library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Library General Public License for more details.
14
15 You should have received a copy of the GNU Library General Public
16 License along with this library; if not, write to the Free
17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18
19 Sam Lantinga
20 slouken@devolution.com
21 */
22
23 #ifdef SAVE_RCSID
24 static char rcsid =
25 "@(#) $Id: SDL_sysmutex.c,v 1.1.2.9 2001/02/10 07:20:04 hercules Exp $";
26 #endif
27
28 #ifdef linux
29 /* Look to see if glibc is available, and if so, what version */
30 #include <features.h>
31
32 #if (__GLIBC__ == 2) && (__GLIBC_MINOR__ == 0)
33 #warning Working around a bug in glibc 2.0 pthreads
34 #undef SDL_USE_PTHREADS
35 /* The bug is actually a problem where threads are suspended, but don't
36 wake up when the thread manager sends them a signal. This is a problem
37 with thread creation too, but it happens less often. :-/
38 We avoid this by using System V IPC for mutexes.
39 */
40 #endif /* glibc 2.0 */
41 #endif /* linux */
42
43 #ifdef SDL_USE_PTHREADS
44
45 #include <stdlib.h>
46 #include <stdio.h>
47 #include <pthread.h>
48
49 #include "SDL_error.h"
50 #include "SDL_thread.h"
51
52
53 struct SDL_mutex {
54 pthread_mutex_t id;
55 #ifdef PTHREAD_NO_RECURSIVE_MUTEX
56 int recursive;
57 pthread_t owner;
58 #endif
59 };
60
61 SDL_mutex *SDL_CreateMutex (void)
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62 {
63 SDL_mutex *mutex;
64 pthread_mutexattr_t attr;
65
66 /* Allocate the structure */
67 mutex = (SDL_mutex *)calloc(1, sizeof(*mutex));
68 if ( mutex ) {
69 pthread_mutexattr_init(&attr);
70 #ifdef PTHREAD_NO_RECURSIVE_MUTEX
71 /* No extra attributes necessary */
72 #else
73 #ifdef linux
74 pthread_mutexattr_setkind_np(&attr, PTHREAD_MUTEX_RECURSIVE_NP);
75 #else
76 pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
77 #endif
78 #endif /* PTHREAD_NO_RECURSIVE_MUTEX */
79 if ( pthread_mutex_init(&mutex->id, &attr) != 0 ) {
80 SDL_SetError("pthread_mutex_init() failed");
81 free(mutex);
82 mutex = NULL;
83 }
84 } else {
85 SDL_OutOfMemory();
86 }
87 return(mutex);
88 }
89
90 void SDL_DestroyMutex(SDL_mutex *mutex)
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91 {
92 if ( mutex ) {
93 pthread_mutex_destroy(&mutex->id);
94 free(mutex);
95 }
96 }
97
98 /* Lock the mutex */
99 int SDL_mutexP(SDL_mutex *mutex)
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100 {
101 int retval;
102 #ifdef PTHREAD_NO_RECURSIVE_MUTEX
103 pthread_t this_thread;
104 #endif
105
106 if ( mutex == NULL ) {
107 SDL_SetError("Passed a NULL mutex");
108 return -1;
109 }
110
111 retval = 0;
112 #ifdef PTHREAD_NO_RECURSIVE_MUTEX
113 this_thread = pthread_self();
114 if ( mutex->owner == this_thread ) {
115 ++mutex->recursive;
116 } else {
117 /* The order of operations is important.
118 We set the locking thread id after we obtain the lock
119 so unlocks from other threads will fail.
120 */
121 if ( pthread_mutex_lock(&mutex->id) == 0 ) {
122 mutex->owner = this_thread;
123 mutex->recursive = 0;
124 } else {
125 SDL_SetError("pthread_mutex_lock() failed");
126 retval = -1;
127 }
128 }
129 #else
130 if ( pthread_mutex_lock(&mutex->id) < 0 ) {
131 SDL_SetError("pthread_mutex_lock() failed");
132 retval = -1;
133 }
134 #endif
135 return retval;
136 }
137
138 int SDL_mutexV(SDL_mutex *mutex)
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139 {
140 int retval;
141
142 if ( mutex == NULL ) {
143 SDL_SetError("Passed a NULL mutex");
144 return -1;
145 }
146
147 retval = 0;
148 #ifdef PTHREAD_NO_RECURSIVE_MUTEX
149 /* We can only unlock the mutex if we own it */
150 if ( pthread_self() == mutex->owner ) {
151 if ( mutex->recursive ) {
152 --mutex->recursive;
153 } else {
154 /* The order of operations is important.
155 First reset the owner so another thread doesn't lock
156 the mutex and set the ownership before we reset it,
157 then release the lock semaphore.
158 */
159 mutex->owner = 0;
160 pthread_mutex_unlock(&mutex->id);
161 }
162 } else {
163 SDL_SetError("mutex not owned by this thread");
164 retval = -1;
165 }
166
167 #else
168 if ( pthread_mutex_unlock(&mutex->id) < 0 ) {
169 SDL_SetError("pthread_mutex_unlock() failed");
170 retval = -1;
171 }
172 #endif /* PTHREAD_NO_RECURSIVE_MUTEX */
173
174 return retval;
175 }
176
177 #else /* Use semaphore implementation */
178
179 #include "generic/SDL_sysmutex.c"
180
181 #endif /* SDL_USE_PTHREADS */