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Diffstat (limited to 'dependencies/include/SDL/SDL_mutex.h')
| -rw-r--r-- | dependencies/include/SDL/SDL_mutex.h | 471 |
1 files changed, 471 insertions, 0 deletions
diff --git a/dependencies/include/SDL/SDL_mutex.h b/dependencies/include/SDL/SDL_mutex.h new file mode 100644 index 0000000..173468f --- /dev/null +++ b/dependencies/include/SDL/SDL_mutex.h @@ -0,0 +1,471 @@ +/* + Simple DirectMedia Layer + Copyright (C) 1997-2022 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. +*/ + +#ifndef SDL_mutex_h_ +#define SDL_mutex_h_ + +/** + * \file SDL_mutex.h + * + * Functions to provide thread synchronization primitives. + */ + +#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_sysmutex.c */ +struct SDL_mutex; +typedef struct SDL_mutex SDL_mutex; + +/** + * Create a new mutex. + * + * All newly-created mutexes begin in the _unlocked_ state. + * + * Calls to SDL_LockMutex() will not return while the mutex is locked by + * another thread. See SDL_TryLockMutex() to attempt to lock without blocking. + * + * SDL mutexes are reentrant. + * + * \returns the initialized and unlocked mutex or NULL on failure; call + * SDL_GetError() for more information. + * + * \since This function is available since SDL 2.0.0. + * + * \sa SDL_DestroyMutex + * \sa SDL_LockMutex + * \sa SDL_TryLockMutex + * \sa SDL_UnlockMutex + */ +extern DECLSPEC SDL_mutex *SDLCALL SDL_CreateMutex(void); + +/** + * Lock the mutex. + * + * This will block until the mutex is available, which is to say it is in the + * unlocked state and the OS has chosen the caller as the next thread to lock + * it. Of all threads waiting to lock the mutex, only one may do so at a time. + * + * It is legal for the owning thread to lock an already-locked mutex. It must + * unlock it the same number of times before it is actually made available for + * other threads in the system (this is known as a "recursive mutex"). + * + * \param mutex the mutex to lock + * \return 0, or -1 on error. + * + * \since This function is available since SDL 2.0.0. + */ +extern DECLSPEC int SDLCALL SDL_LockMutex(SDL_mutex * mutex); +#define SDL_mutexP(m) SDL_LockMutex(m) + +/** + * Try to lock a mutex without blocking. + * + * This works just like SDL_LockMutex(), but if the mutex is not available, + * this function returns `SDL_MUTEX_TIMEOUT` immediately. + * + * This technique is useful if you need exclusive access to a resource but + * don't want to wait for it, and will return to it to try again later. + * + * \param mutex the mutex to try to lock + * \returns 0, `SDL_MUTEX_TIMEDOUT`, or -1 on error; call SDL_GetError() for + * more information. + * + * \since This function is available since SDL 2.0.0. + * + * \sa SDL_CreateMutex + * \sa SDL_DestroyMutex + * \sa SDL_LockMutex + * \sa SDL_UnlockMutex + */ +extern DECLSPEC int SDLCALL SDL_TryLockMutex(SDL_mutex * mutex); + +/** + * Unlock the mutex. + * + * It is legal for the owning thread to lock an already-locked mutex. It must + * unlock it the same number of times before it is actually made available for + * other threads in the system (this is known as a "recursive mutex"). + * + * It is an error to unlock a mutex that has not been locked by the current + * thread, and doing so results in undefined behavior. + * + * It is also an error to unlock a mutex that isn't locked at all. + * + * \param mutex the mutex to unlock. + * \returns 0, or -1 on error. + * + * \since This function is available since SDL 2.0.0. + */ +extern DECLSPEC int SDLCALL SDL_UnlockMutex(SDL_mutex * mutex); +#define SDL_mutexV(m) SDL_UnlockMutex(m) + +/** + * Destroy a mutex created with SDL_CreateMutex(). + * + * This function must be called on any mutex that is no longer needed. Failure + * to destroy a mutex will result in a system memory or resource leak. While + * it is safe to destroy a mutex that is _unlocked_, it is not safe to attempt + * to destroy a locked mutex, and may result in undefined behavior depending + * on the platform. + * + * \param mutex the mutex to destroy + * + * \since This function is available since SDL 2.0.0. + * + * \sa SDL_CreateMutex + * \sa SDL_LockMutex + * \sa SDL_TryLockMutex + * \sa SDL_UnlockMutex + */ +extern DECLSPEC void SDLCALL SDL_DestroyMutex(SDL_mutex * mutex); + +/* @} *//* Mutex functions */ + + +/** + * \name Semaphore functions + */ +/* @{ */ + +/* The SDL semaphore structure, defined in SDL_syssem.c */ +struct SDL_semaphore; +typedef struct SDL_semaphore SDL_sem; + +/** + * Create a semaphore. + * + * This function creates a new semaphore and initializes it with the value + * `initial_value`. Each wait operation on the semaphore will atomically + * decrement the semaphore value and potentially block if the semaphore value + * is 0. Each post operation will atomically increment the semaphore value and + * wake waiting threads and allow them to retry the wait operation. + * + * \param initial_value the starting value of the semaphore + * \returns a new semaphore or NULL on failure; call SDL_GetError() for more + * information. + * + * \since This function is available since SDL 2.0.0. + * + * \sa SDL_DestroySemaphore + * \sa SDL_SemPost + * \sa SDL_SemTryWait + * \sa SDL_SemValue + * \sa SDL_SemWait + * \sa SDL_SemWaitTimeout + */ +extern DECLSPEC SDL_sem *SDLCALL SDL_CreateSemaphore(Uint32 initial_value); + +/** + * Destroy a semaphore. + * + * It is not safe to destroy a semaphore if there are threads currently + * waiting on it. + * + * \param sem the semaphore to destroy + * + * \since This function is available since SDL 2.0.0. + * + * \sa SDL_CreateSemaphore + * \sa SDL_SemPost + * \sa SDL_SemTryWait + * \sa SDL_SemValue + * \sa SDL_SemWait + * \sa SDL_SemWaitTimeout + */ +extern DECLSPEC void SDLCALL SDL_DestroySemaphore(SDL_sem * sem); + +/** + * Wait until a semaphore has a positive value and then decrements it. + * + * This function suspends the calling thread until either the semaphore + * pointed to by `sem` has a positive value or the call is interrupted by a + * signal or error. If the call is successful it will atomically decrement the + * semaphore value. + * + * This function is the equivalent of calling SDL_SemWaitTimeout() with a time + * length of `SDL_MUTEX_MAXWAIT`. + * + * \param sem the semaphore wait on + * \returns 0 on success or a negative error code on failure; call + * SDL_GetError() for more information. + * + * \since This function is available since SDL 2.0.0. + * + * \sa SDL_CreateSemaphore + * \sa SDL_DestroySemaphore + * \sa SDL_SemPost + * \sa SDL_SemTryWait + * \sa SDL_SemValue + * \sa SDL_SemWait + * \sa SDL_SemWaitTimeout + */ +extern DECLSPEC int SDLCALL SDL_SemWait(SDL_sem * sem); + +/** + * See if a semaphore has a positive value and decrement it if it does. + * + * This function checks to see if the semaphore pointed to by `sem` has a + * positive value and atomically decrements the semaphore value if it does. If + * the semaphore doesn't have a positive value, the function immediately + * returns SDL_MUTEX_TIMEDOUT. + * + * \param sem the semaphore to wait on + * \returns 0 if the wait succeeds, `SDL_MUTEX_TIMEDOUT` if the wait would + * block, or a negative error code on failure; call SDL_GetError() + * for more information. + * + * \since This function is available since SDL 2.0.0. + * + * \sa SDL_CreateSemaphore + * \sa SDL_DestroySemaphore + * \sa SDL_SemPost + * \sa SDL_SemValue + * \sa SDL_SemWait + * \sa SDL_SemWaitTimeout + */ +extern DECLSPEC int SDLCALL SDL_SemTryWait(SDL_sem * sem); + +/** + * Wait until a semaphore has a positive value and then decrements it. + * + * This function suspends the calling thread until either the semaphore + * pointed to by `sem` has a positive value, the call is interrupted by a + * signal or error, or the specified time has elapsed. If the call is + * successful it will atomically decrement the semaphore value. + * + * \param sem the semaphore to wait on + * \param ms the length of the timeout, in milliseconds + * \returns 0 if the wait succeeds, `SDL_MUTEX_TIMEDOUT` if the wait does not + * succeed in the allotted time, or a negative error code on failure; + * call SDL_GetError() for more information. + * + * \since This function is available since SDL 2.0.0. + * + * \sa SDL_CreateSemaphore + * \sa SDL_DestroySemaphore + * \sa SDL_SemPost + * \sa SDL_SemTryWait + * \sa SDL_SemValue + * \sa SDL_SemWait + */ +extern DECLSPEC int SDLCALL SDL_SemWaitTimeout(SDL_sem * sem, Uint32 ms); + +/** + * Atomically increment a semaphore's value and wake waiting threads. + * + * \param sem the semaphore to increment + * \returns 0 on success or a negative error code on failure; call + * SDL_GetError() for more information. + * + * \since This function is available since SDL 2.0.0. + * + * \sa SDL_CreateSemaphore + * \sa SDL_DestroySemaphore + * \sa SDL_SemTryWait + * \sa SDL_SemValue + * \sa SDL_SemWait + * \sa SDL_SemWaitTimeout + */ +extern DECLSPEC int SDLCALL SDL_SemPost(SDL_sem * sem); + +/** + * Get the current value of a semaphore. + * + * \param sem the semaphore to query + * \returns the current value of the semaphore. + * + * \since This function is available since SDL 2.0.0. + * + * \sa SDL_CreateSemaphore + */ +extern DECLSPEC Uint32 SDLCALL SDL_SemValue(SDL_sem * sem); + +/* @} *//* Semaphore functions */ + + +/** + * \name Condition variable functions + */ +/* @{ */ + +/* The SDL condition variable structure, defined in SDL_syscond.c */ +struct SDL_cond; +typedef struct SDL_cond SDL_cond; + +/** + * Create a condition variable. + * + * \returns a new condition variable or NULL on failure; call SDL_GetError() + * for more information. + * + * \since This function is available since SDL 2.0.0. + * + * \sa SDL_CondBroadcast + * \sa SDL_CondSignal + * \sa SDL_CondWait + * \sa SDL_CondWaitTimeout + * \sa SDL_DestroyCond + */ +extern DECLSPEC SDL_cond *SDLCALL SDL_CreateCond(void); + +/** + * Destroy a condition variable. + * + * \param cond the condition variable to destroy + * + * \since This function is available since SDL 2.0.0. + * + * \sa SDL_CondBroadcast + * \sa SDL_CondSignal + * \sa SDL_CondWait + * \sa SDL_CondWaitTimeout + * \sa SDL_CreateCond + */ +extern DECLSPEC void SDLCALL SDL_DestroyCond(SDL_cond * cond); + +/** + * Restart one of the threads that are waiting on the condition variable. + * + * \param cond the condition variable to signal + * \returns 0 on success or a negative error code on failure; call + * SDL_GetError() for more information. + * + * \since This function is available since SDL 2.0.0. + * + * \sa SDL_CondBroadcast + * \sa SDL_CondWait + * \sa SDL_CondWaitTimeout + * \sa SDL_CreateCond + * \sa SDL_DestroyCond + */ +extern DECLSPEC int SDLCALL SDL_CondSignal(SDL_cond * cond); + +/** + * Restart all threads that are waiting on the condition variable. + * + * \param cond the condition variable to signal + * \returns 0 on success or a negative error code on failure; call + * SDL_GetError() for more information. + * + * \since This function is available since SDL 2.0.0. + * + * \sa SDL_CondSignal + * \sa SDL_CondWait + * \sa SDL_CondWaitTimeout + * \sa SDL_CreateCond + * \sa SDL_DestroyCond + */ +extern DECLSPEC int SDLCALL SDL_CondBroadcast(SDL_cond * cond); + +/** + * Wait until a condition variable is signaled. + * + * This function unlocks the specified `mutex` and waits for another thread to + * call SDL_CondSignal() or SDL_CondBroadcast() on the condition variable + * `cond`. Once the condition variable is signaled, the mutex is re-locked and + * the function returns. + * + * The mutex must be locked before calling this function. + * + * This function is the equivalent of calling SDL_CondWaitTimeout() with a + * time length of `SDL_MUTEX_MAXWAIT`. + * + * \param cond the condition variable to wait on + * \param mutex the mutex used to coordinate thread access + * \returns 0 when it is signaled or a negative error code on failure; call + * SDL_GetError() for more information. + * + * \since This function is available since SDL 2.0.0. + * + * \sa SDL_CondBroadcast + * \sa SDL_CondSignal + * \sa SDL_CondWaitTimeout + * \sa SDL_CreateCond + * \sa SDL_DestroyCond + */ +extern DECLSPEC int SDLCALL SDL_CondWait(SDL_cond * cond, SDL_mutex * mutex); + +/** + * Wait until a condition variable is signaled or a certain time has passed. + * + * This function unlocks the specified `mutex` and waits for another thread to + * call SDL_CondSignal() or SDL_CondBroadcast() on the condition variable + * `cond`, or for the specified time to elapse. Once the condition variable is + * signaled or the time elapsed, the mutex is re-locked and the function + * returns. + * + * The mutex must be locked before calling this function. + * + * \param cond the condition variable to wait on + * \param mutex the mutex used to coordinate thread access + * \param ms the maximum time to wait, in milliseconds, or `SDL_MUTEX_MAXWAIT` + * to wait indefinitely + * \returns 0 if the condition variable is signaled, `SDL_MUTEX_TIMEDOUT` if + * the condition is not signaled in the allotted time, or a negative + * error code on failure; call SDL_GetError() for more information. + * + * \since This function is available since SDL 2.0.0. + * + * \sa SDL_CondBroadcast + * \sa SDL_CondSignal + * \sa SDL_CondWait + * \sa SDL_CreateCond + * \sa SDL_DestroyCond + */ +extern DECLSPEC int SDLCALL SDL_CondWaitTimeout(SDL_cond * cond, + SDL_mutex * mutex, Uint32 ms); + +/* @} *//* Condition variable functions */ + + +/* Ends C function definitions when using C++ */ +#ifdef __cplusplus +} +#endif +#include "close_code.h" + +#endif /* SDL_mutex_h_ */ + +/* vi: set ts=4 sw=4 expandtab: */ |