SDL Wiki
(This is the documentation for SDL3, which is under heavy development and the API is changing! SDL2 is the current stable version!)


Wait until a condition variable is signaled or a certain time has passed.


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 to wait indefinitely

Return Value

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.


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. Locking the mutex recursively (more than once) is not supported and leads to undefined behavior.


This function is available since SDL 3.0.0.

Code Examples

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) {
        while (!condition && SDL_CondWaitTimeout(cond, lock, timeout) == 0) {

        if (condition) {

        ... do some periodic work

Thread B:
    condition = SDL_TRUE;

CategoryAPI, CategoryMutex

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