1 /* 2 SDL - Simple DirectMedia Layer 3 Copyright (C) 1997-2006 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 (at) libsdl.org 21 */ 22 #include "SDL_config.h" 23 24 #include <pthread.h> 25 26 #include "SDL_thread.h" 27 28 #if !SDL_THREAD_PTHREAD_RECURSIVE_MUTEX && \ 29 !SDL_THREAD_PTHREAD_RECURSIVE_MUTEX_NP 30 #define FAKE_RECURSIVE_MUTEX 31 #endif 32 33 struct SDL_mutex { 34 pthread_mutex_t id; 35 #if FAKE_RECURSIVE_MUTEX 36 int recursive; 37 pthread_t owner; 38 #endif 39 }; 40 41 SDL_mutex *SDL_CreateMutex (void) 42 { 43 SDL_mutex *mutex; 44 pthread_mutexattr_t attr; 45 46 /* Allocate the structure */ 47 mutex = (SDL_mutex *)SDL_calloc(1, sizeof(*mutex)); 48 if ( mutex ) { 49 pthread_mutexattr_init(&attr); 50 #if SDL_THREAD_PTHREAD_RECURSIVE_MUTEX 51 pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE); 52 #elif SDL_THREAD_PTHREAD_RECURSIVE_MUTEX_NP 53 pthread_mutexattr_setkind_np(&attr, PTHREAD_MUTEX_RECURSIVE_NP); 54 #else 55 /* No extra attributes necessary */ 56 #endif 57 if ( pthread_mutex_init(&mutex->id, &attr) != 0 ) { 58 SDL_SetError("pthread_mutex_init() failed"); 59 SDL_free(mutex); 60 mutex = NULL; 61 } 62 } else { 63 SDL_OutOfMemory(); 64 } 65 return(mutex); 66 } 67 68 void SDL_DestroyMutex(SDL_mutex *mutex) 69 { 70 if ( mutex ) { 71 pthread_mutex_destroy(&mutex->id); 72 SDL_free(mutex); 73 } 74 } 75 76 /* Lock the mutex */ 77 int SDL_mutexP(SDL_mutex *mutex) 78 { 79 int retval; 80 #if FAKE_RECURSIVE_MUTEX 81 pthread_t this_thread; 82 #endif 83 84 if ( mutex == NULL ) { 85 SDL_SetError("Passed a NULL mutex"); 86 return -1; 87 } 88 89 retval = 0; 90 #if FAKE_RECURSIVE_MUTEX 91 this_thread = pthread_self(); 92 if ( mutex->owner == this_thread ) { 93 ++mutex->recursive; 94 } else { 95 /* The order of operations is important. 96 We set the locking thread id after we obtain the lock 97 so unlocks from other threads will fail. 98 */ 99 if ( pthread_mutex_lock(&mutex->id) == 0 ) { 100 mutex->owner = this_thread; 101 mutex->recursive = 0; 102 } else { 103 SDL_SetError("pthread_mutex_lock() failed"); 104 retval = -1; 105 } 106 } 107 #else 108 if ( pthread_mutex_lock(&mutex->id) < 0 ) { 109 SDL_SetError("pthread_mutex_lock() failed"); 110 retval = -1; 111 } 112 #endif 113 return retval; 114 } 115 116 int SDL_mutexV(SDL_mutex *mutex) 117 { 118 int retval; 119 120 if ( mutex == NULL ) { 121 SDL_SetError("Passed a NULL mutex"); 122 return -1; 123 } 124 125 retval = 0; 126 #if FAKE_RECURSIVE_MUTEX 127 /* We can only unlock the mutex if we own it */ 128 if ( pthread_self() == mutex->owner ) { 129 if ( mutex->recursive ) { 130 --mutex->recursive; 131 } else { 132 /* The order of operations is important. 133 First reset the owner so another thread doesn't lock 134 the mutex and set the ownership before we reset it, 135 then release the lock semaphore. 136 */ 137 mutex->owner = 0; 138 pthread_mutex_unlock(&mutex->id); 139 } 140 } else { 141 SDL_SetError("mutex not owned by this thread"); 142 retval = -1; 143 } 144 145 #else 146 if ( pthread_mutex_unlock(&mutex->id) < 0 ) { 147 SDL_SetError("pthread_mutex_unlock() failed"); 148 retval = -1; 149 } 150 #endif /* FAKE_RECURSIVE_MUTEX */ 151 152 return retval; 153 } 154
