e14743d1 |
1 | /* |
2 | SDL - Simple DirectMedia Layer |
3 | Copyright (C) 1997-2009 Sam Lantinga |
4 | |
5 | This library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 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 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with this library; if not, write to the Free Software |
17 | Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
18 | |
19 | Sam Lantinga |
20 | slouken@libsdl.org |
21 | */ |
22 | #include "SDL_config.h" |
23 | |
24 | /* RISC OS implementations uses pthreads based on linux code */ |
25 | |
26 | #include "SDL_thread.h" |
27 | |
28 | #if SDL_THREADS_DISABLED |
29 | #include "../generic/SDL_sysmutex.c" |
30 | #else |
31 | |
32 | #include <pthread.h> |
33 | |
34 | struct SDL_mutex { |
35 | pthread_mutex_t id; |
36 | #if SDL_THREAD_PTHREAD_NO_RECURSIVE_MUTEX |
37 | int recursive; |
38 | pthread_t owner; |
39 | #endif |
40 | }; |
41 | |
42 | SDL_mutex *SDL_CreateMutex (void) |
43 | { |
44 | SDL_mutex *mutex; |
45 | pthread_mutexattr_t attr; |
46 | |
47 | /* Allocate the structure */ |
48 | mutex = (SDL_mutex *)SDL_calloc(1, sizeof(*mutex)); |
49 | if ( mutex ) { |
50 | pthread_mutexattr_init(&attr); |
51 | #if SDL_THREAD_PTHREAD_NO_RECURSIVE_MUTEX |
52 | /* No extra attributes necessary */ |
53 | #else |
54 | pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE); |
55 | #endif /* SDL_THREAD_PTHREAD_NO_RECURSIVE_MUTEX */ |
56 | if ( pthread_mutex_init(&mutex->id, &attr) != 0 ) { |
57 | SDL_SetError("pthread_mutex_init() failed"); |
58 | SDL_free(mutex); |
59 | mutex = NULL; |
60 | } |
61 | } else { |
62 | SDL_OutOfMemory(); |
63 | } |
64 | return(mutex); |
65 | } |
66 | |
67 | void SDL_DestroyMutex(SDL_mutex *mutex) |
68 | { |
69 | if ( mutex ) { |
70 | pthread_mutex_destroy(&mutex->id); |
71 | SDL_free(mutex); |
72 | } |
73 | } |
74 | |
75 | /* Lock the mutex */ |
76 | int SDL_mutexP(SDL_mutex *mutex) |
77 | { |
78 | int retval; |
79 | #if SDL_THREAD_PTHREAD_NO_RECURSIVE_MUTEX |
80 | pthread_t this_thread; |
81 | #endif |
82 | |
83 | if ( mutex == NULL ) { |
84 | SDL_SetError("Passed a NULL mutex"); |
85 | return -1; |
86 | } |
87 | |
88 | retval = 0; |
89 | #if SDL_THREAD_PTHREAD_NO_RECURSIVE_MUTEX |
90 | this_thread = pthread_self(); |
91 | if ( mutex->owner == this_thread ) { |
92 | ++mutex->recursive; |
93 | } else { |
94 | /* The order of operations is important. |
95 | We set the locking thread id after we obtain the lock |
96 | so unlocks from other threads will fail. |
97 | */ |
98 | if ( pthread_mutex_lock(&mutex->id) == 0 ) { |
99 | mutex->owner = this_thread; |
100 | mutex->recursive = 0; |
101 | } else { |
102 | SDL_SetError("pthread_mutex_lock() failed"); |
103 | retval = -1; |
104 | } |
105 | } |
106 | #else |
107 | if ( pthread_mutex_lock(&mutex->id) < 0 ) { |
108 | SDL_SetError("pthread_mutex_lock() failed"); |
109 | retval = -1; |
110 | } |
111 | #endif |
112 | return retval; |
113 | } |
114 | |
115 | int SDL_mutexV(SDL_mutex *mutex) |
116 | { |
117 | int retval; |
118 | |
119 | if ( mutex == NULL ) { |
120 | SDL_SetError("Passed a NULL mutex"); |
121 | return -1; |
122 | } |
123 | |
124 | retval = 0; |
125 | #if SDL_THREAD_PTHREAD_NO_RECURSIVE_MUTEX |
126 | /* We can only unlock the mutex if we own it */ |
127 | if ( pthread_self() == mutex->owner ) { |
128 | if ( mutex->recursive ) { |
129 | --mutex->recursive; |
130 | } else { |
131 | /* The order of operations is important. |
132 | First reset the owner so another thread doesn't lock |
133 | the mutex and set the ownership before we reset it, |
134 | then release the lock semaphore. |
135 | */ |
136 | mutex->owner = 0; |
137 | pthread_mutex_unlock(&mutex->id); |
138 | } |
139 | } else { |
140 | SDL_SetError("mutex not owned by this thread"); |
141 | retval = -1; |
142 | } |
143 | |
144 | #else |
145 | if ( pthread_mutex_unlock(&mutex->id) < 0 ) { |
146 | SDL_SetError("pthread_mutex_unlock() failed"); |
147 | retval = -1; |
148 | } |
149 | #endif /* SDL_THREAD_PTHREAD_NO_RECURSIVE_MUTEX */ |
150 | |
151 | return retval; |
152 | } |
153 | #endif |