###### (This is the documentation for SDL3, which is under heavy development and the API is changing! [SDL2](https://wiki.libsdl.org/SDL2/) is the current stable version!) # SDL_CondWaitTimeout Wait until a condition variable is signaled or a certain time has passed. ## Syntax ```c int SDL_CondWaitTimeout(SDL_cond *cond, SDL_mutex *mutex, Sint32 timeoutMS); ``` ## Function Parameters | | | | ----------------- | ----------------------------------------------------------------------------------------------------------- | | **cond** | the condition variable to wait on | | **mutex** | the mutex used to coordinate thread access | | **timeoutMS** | the maximum time to wait, in milliseconds, or [`SDL_MUTEX_MAXWAIT`](SDL_MUTEX_MAXWAIT) to wait indefinitely | ## Return Value Returns 0 if the condition variable is signaled, [`SDL_MUTEX_TIMEDOUT`](SDL_MUTEX_TIMEDOUT) if the condition is not signaled in the allotted time, or a negative error code on failure; call [SDL_GetError](SDL_GetError)() for more information. ## Remarks This function unlocks the specified `mutex` and waits for another thread to call [SDL_CondSignal](SDL_CondSignal)() or [SDL_CondBroadcast](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. Locking the mutex recursively (more than once) is not supported and leads to undefined behavior. ## Version This function is available since SDL 3.0.0. ## Code Examples ```c++ SDL_bool condition = SDL_FALSE; SDL_mutex *lock; SDL_cond *cond; lock = SDL_CreateMutex(); cond = SDL_CreateCond(); . . Thread A: const Uint32 timeout = 1000; /* wake up every second */ while (!done) { SDL_LockMutex(lock); while (!condition && SDL_CondWaitTimeout(cond, lock, timeout) == 0) { continue; } SDL_UnlockMutex(lock); if (condition) { ... } ... do some periodic work } Thread B: SDL_LockMutex(lock); ... condition = SDL_TRUE; ... SDL_CondSignal(cond); SDL_UnlockMutex(lock); . . SDL_DestroyCond(cond); SDL_DestroyMutex(lock); ``` ## Related Functions * [SDL_CondBroadcast](SDL_CondBroadcast) * [SDL_CondSignal](SDL_CondSignal) * [SDL_CondWait](SDL_CondWait) * [SDL_CreateCond](SDL_CreateCond) * [SDL_DestroyCond](SDL_DestroyCond) ---- [CategoryAPI](CategoryAPI), [CategoryMutex](CategoryMutex)