| /* |
| Simple DirectMedia Layer |
| Copyright (C) 1997-2021 Sam Lantinga <slouken@libsdl.org> |
| |
| This software is provided 'as-is', without any express or implied |
| warranty. In no event will the authors be held liable for any damages |
| arising from the use of this software. |
| |
| Permission is granted to anyone to use this software for any purpose, |
| including commercial applications, and to alter it and redistribute it |
| freely, subject to the following restrictions: |
| |
| 1. The origin of this software must not be misrepresented; you must not |
| claim that you wrote the original software. If you use this software |
| in a product, an acknowledgment in the product documentation would be |
| appreciated but is not required. |
| 2. Altered source versions must be plainly marked as such, and must not be |
| misrepresented as being the original software. |
| 3. This notice may not be removed or altered from any source distribution. |
| */ |
| #include "../../SDL_internal.h" |
| |
| #include <errno.h> |
| #include <pthread.h> |
| |
| #include "SDL_thread.h" |
| |
| #if !SDL_THREAD_PTHREAD_RECURSIVE_MUTEX && \ |
| !SDL_THREAD_PTHREAD_RECURSIVE_MUTEX_NP |
| #define FAKE_RECURSIVE_MUTEX 1 |
| #endif |
| |
| struct SDL_mutex |
| { |
| pthread_mutex_t id; |
| #if FAKE_RECURSIVE_MUTEX |
| int recursive; |
| pthread_t owner; |
| #endif |
| }; |
| |
| SDL_mutex * |
| SDL_CreateMutex(void) |
| { |
| SDL_mutex *mutex; |
| pthread_mutexattr_t attr; |
| |
| /* Allocate the structure */ |
| mutex = (SDL_mutex *) SDL_calloc(1, sizeof(*mutex)); |
| if (mutex) { |
| pthread_mutexattr_init(&attr); |
| #if SDL_THREAD_PTHREAD_RECURSIVE_MUTEX |
| pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE); |
| #elif SDL_THREAD_PTHREAD_RECURSIVE_MUTEX_NP |
| pthread_mutexattr_setkind_np(&attr, PTHREAD_MUTEX_RECURSIVE_NP); |
| #else |
| /* No extra attributes necessary */ |
| #endif |
| if (pthread_mutex_init(&mutex->id, &attr) != 0) { |
| SDL_SetError("pthread_mutex_init() failed"); |
| SDL_free(mutex); |
| mutex = NULL; |
| } |
| } else { |
| SDL_OutOfMemory(); |
| } |
| return (mutex); |
| } |
| |
| void |
| SDL_DestroyMutex(SDL_mutex * mutex) |
| { |
| if (mutex) { |
| pthread_mutex_destroy(&mutex->id); |
| SDL_free(mutex); |
| } |
| } |
| |
| /* Lock the mutex */ |
| int |
| SDL_LockMutex(SDL_mutex * mutex) |
| { |
| #if FAKE_RECURSIVE_MUTEX |
| pthread_t this_thread; |
| #endif |
| |
| if (mutex == NULL) { |
| return SDL_SetError("Passed a NULL mutex"); |
| } |
| |
| #if FAKE_RECURSIVE_MUTEX |
| this_thread = pthread_self(); |
| if (mutex->owner == this_thread) { |
| ++mutex->recursive; |
| } else { |
| /* The order of operations is important. |
| We set the locking thread id after we obtain the lock |
| so unlocks from other threads will fail. |
| */ |
| if (pthread_mutex_lock(&mutex->id) == 0) { |
| mutex->owner = this_thread; |
| mutex->recursive = 0; |
| } else { |
| return SDL_SetError("pthread_mutex_lock() failed"); |
| } |
| } |
| #else |
| if (pthread_mutex_lock(&mutex->id) != 0) { |
| return SDL_SetError("pthread_mutex_lock() failed"); |
| } |
| #endif |
| return 0; |
| } |
| |
| int |
| SDL_TryLockMutex(SDL_mutex * mutex) |
| { |
| int retval; |
| int result; |
| #if FAKE_RECURSIVE_MUTEX |
| pthread_t this_thread; |
| #endif |
| |
| if (mutex == NULL) { |
| return SDL_SetError("Passed a NULL mutex"); |
| } |
| |
| retval = 0; |
| #if FAKE_RECURSIVE_MUTEX |
| this_thread = pthread_self(); |
| if (mutex->owner == this_thread) { |
| ++mutex->recursive; |
| } else { |
| /* The order of operations is important. |
| We set the locking thread id after we obtain the lock |
| so unlocks from other threads will fail. |
| */ |
| result = pthread_mutex_trylock(&mutex->id); |
| if (result == 0) { |
| mutex->owner = this_thread; |
| mutex->recursive = 0; |
| } else if (result == EBUSY) { |
| retval = SDL_MUTEX_TIMEDOUT; |
| } else { |
| retval = SDL_SetError("pthread_mutex_trylock() failed"); |
| } |
| } |
| #else |
| result = pthread_mutex_trylock(&mutex->id); |
| if (result != 0) { |
| if (result == EBUSY) { |
| retval = SDL_MUTEX_TIMEDOUT; |
| } else { |
| retval = SDL_SetError("pthread_mutex_trylock() failed"); |
| } |
| } |
| #endif |
| return retval; |
| } |
| |
| int |
| SDL_UnlockMutex(SDL_mutex * mutex) |
| { |
| if (mutex == NULL) { |
| return SDL_SetError("Passed a NULL mutex"); |
| } |
| |
| #if FAKE_RECURSIVE_MUTEX |
| /* We can only unlock the mutex if we own it */ |
| if (pthread_self() == mutex->owner) { |
| if (mutex->recursive) { |
| --mutex->recursive; |
| } else { |
| /* The order of operations is important. |
| First reset the owner so another thread doesn't lock |
| the mutex and set the ownership before we reset it, |
| then release the lock semaphore. |
| */ |
| mutex->owner = 0; |
| pthread_mutex_unlock(&mutex->id); |
| } |
| } else { |
| return SDL_SetError("mutex not owned by this thread"); |
| } |
| |
| #else |
| if (pthread_mutex_unlock(&mutex->id) != 0) { |
| return SDL_SetError("pthread_mutex_unlock() failed"); |
| } |
| #endif /* FAKE_RECURSIVE_MUTEX */ |
| |
| return 0; |
| } |
| |
| /* vi: set ts=4 sw=4 expandtab: */ |