As I understand it, pthread_cond_timedwait is to be used by taking current time, then calculating absolute time when pthread_cond_timedwait should exit if condition is not signalled.
Is there a simple way to use this function to reliably perform a periodic task (the problem being changes in time between the point where current time is taken and call to pthread_cond_timedwait)?
I have a periodic task that should run ~every second.
do {
pthread_mutex_lock(mutex);
tx = gettimeofday + 1 second;
do_some_simple_periodic_task();
pthread_cond_timedwait(condition, mutex, tx);
pthread_mutex_unlock(mutex);
} while (!some_exit_condition);
Condition is signalled if context (including some_exit_condition) is updated.
Is there a way to use monotonic timer or something similar with this? If not, what is the use case for pthread_cond_timedwait at all? Only for cases, where you don't care about additional hour of delay?
I have seen a solution where another thread signals this one periodically (How to make pthread_cond_timedwait() robust against system clock manipulations?), but it seems like a hack.
Is there a different & better way to make thread sleep for some interval (not prone to wall clock changes) but respond immediately to external condition?