Mercurial > sdl-ios-xcode
view include/SDL_mutex.h @ 5107:99acf3d856cb SDL-1.2
Colin Leroy 2011-01-26 04:24:20 PST
the pthread implementation of SDL_SemWaitTimeout() uses busy waiting, while
pthread's sem_timedwait() does work. Attached are patches that make use of it
author | Sam Lantinga <slouken@libsdl.org> |
---|---|
date | Thu, 27 Jan 2011 00:33:26 -0800 |
parents | 4c4113c2162c |
children |
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/* SDL - Simple DirectMedia Layer Copyright (C) 1997-2009 Sam Lantinga This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA Sam Lantinga slouken@libsdl.org */ #ifndef _SDL_mutex_h #define _SDL_mutex_h /** @file SDL_mutex.h * Functions to provide thread synchronization primitives * * @note These are independent of the other SDL routines. */ #include "SDL_stdinc.h" #include "SDL_error.h" #include "begin_code.h" /* Set up for C function definitions, even when using C++ */ #ifdef __cplusplus extern "C" { #endif /** Synchronization functions which can time out return this value * if they time out. */ #define SDL_MUTEX_TIMEDOUT 1 /** This is the timeout value which corresponds to never time out */ #define SDL_MUTEX_MAXWAIT (~(Uint32)0) /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ /** @name Mutex functions */ /*@{*/ /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ /** The SDL mutex structure, defined in SDL_mutex.c */ struct SDL_mutex; typedef struct SDL_mutex SDL_mutex; /** Create a mutex, initialized unlocked */ extern DECLSPEC SDL_mutex * SDLCALL SDL_CreateMutex(void); #define SDL_LockMutex(m) SDL_mutexP(m) /** Lock the mutex * @return 0, or -1 on error */ extern DECLSPEC int SDLCALL SDL_mutexP(SDL_mutex *mutex); #define SDL_UnlockMutex(m) SDL_mutexV(m) /** Unlock the mutex * @return 0, or -1 on error * * It is an error to unlock a mutex that has not been locked by * the current thread, and doing so results in undefined behavior. */ extern DECLSPEC int SDLCALL SDL_mutexV(SDL_mutex *mutex); /** Destroy a mutex */ extern DECLSPEC void SDLCALL SDL_DestroyMutex(SDL_mutex *mutex); /*@}*/ /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ /** @name Semaphore functions */ /*@{*/ /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ /** The SDL semaphore structure, defined in SDL_sem.c */ struct SDL_semaphore; typedef struct SDL_semaphore SDL_sem; /** Create a semaphore, initialized with value, returns NULL on failure. */ extern DECLSPEC SDL_sem * SDLCALL SDL_CreateSemaphore(Uint32 initial_value); /** Destroy a semaphore */ extern DECLSPEC void SDLCALL SDL_DestroySemaphore(SDL_sem *sem); /** * This function suspends the calling thread until the semaphore pointed * to by sem has a positive count. It then atomically decreases the semaphore * count. */ extern DECLSPEC int SDLCALL SDL_SemWait(SDL_sem *sem); /** Non-blocking variant of SDL_SemWait(). * @return 0 if the wait succeeds, * SDL_MUTEX_TIMEDOUT if the wait would block, and -1 on error. */ extern DECLSPEC int SDLCALL SDL_SemTryWait(SDL_sem *sem); /** Variant of SDL_SemWait() with a timeout in milliseconds, returns 0 if * the wait succeeds, SDL_MUTEX_TIMEDOUT if the wait does not succeed in * the allotted time, and -1 on error. * * On some platforms this function is implemented by looping with a delay * of 1 ms, and so should be avoided if possible. */ extern DECLSPEC int SDLCALL SDL_SemWaitTimeout(SDL_sem *sem, Uint32 ms); /** Atomically increases the semaphore's count (not blocking). * @return 0, or -1 on error. */ extern DECLSPEC int SDLCALL SDL_SemPost(SDL_sem *sem); /** Returns the current count of the semaphore */ extern DECLSPEC Uint32 SDLCALL SDL_SemValue(SDL_sem *sem); /*@}*/ /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ /** @name Condition_variable_functions */ /*@{*/ /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ /*@{*/ /** The SDL condition variable structure, defined in SDL_cond.c */ struct SDL_cond; typedef struct SDL_cond SDL_cond; /*@}*/ /** Create a condition variable */ extern DECLSPEC SDL_cond * SDLCALL SDL_CreateCond(void); /** Destroy a condition variable */ extern DECLSPEC void SDLCALL SDL_DestroyCond(SDL_cond *cond); /** Restart one of the threads that are waiting on the condition variable, * @return 0 or -1 on error. */ extern DECLSPEC int SDLCALL SDL_CondSignal(SDL_cond *cond); /** Restart all threads that are waiting on the condition variable, * @return 0 or -1 on error. */ extern DECLSPEC int SDLCALL SDL_CondBroadcast(SDL_cond *cond); /** Wait on the condition variable, unlocking the provided mutex. * The mutex must be locked before entering this function! * The mutex is re-locked once the condition variable is signaled. * @return 0 when it is signaled, or -1 on error. */ extern DECLSPEC int SDLCALL SDL_CondWait(SDL_cond *cond, SDL_mutex *mut); /** Waits for at most 'ms' milliseconds, and returns 0 if the condition * variable is signaled, SDL_MUTEX_TIMEDOUT if the condition is not * signaled in the allotted time, and -1 on error. * On some platforms this function is implemented by looping with a delay * of 1 ms, and so should be avoided if possible. */ extern DECLSPEC int SDLCALL SDL_CondWaitTimeout(SDL_cond *cond, SDL_mutex *mutex, Uint32 ms); /*@}*/ /* Ends C function definitions when using C++ */ #ifdef __cplusplus } #endif #include "close_code.h" #endif /* _SDL_mutex_h */