In case of Events on Windows, If no threads are waiting, the event object's state remains signaled. What happens in case of pthread_cond_signal, what happens in case if no threads are blocked?
For pthread_cond_signal()... if there are no threads waiting at that exact moment, nothing happens, nothing at all -- in particular, the signal is completely forgotten, it is as if it had never happened.
IMHO POSIX "condition variables" are badly named, because the name suggests that the "condition variable" has a value, and it is natural to suppose that the value might collect pending signals. Nothing could be further from the truth. (For that you need "semaphores".)
The "state" associated with the "condition" is what matters. A thread which needs to wait for the "state" to have a particular value will:
pthread_mutex_lock(foo_mutex) ;
while (...state not as required...)
pthread_cond_wait(foo_cond, foo_mutex) ;
...perhaps update the state...
pthread_mutex_unlock(foo_mutex) ;
A thread which updates the "state" such that some other thread may now continue, will:
pthread_mutex_lock(foo_mutex) ;
...update the state...
if (...there may be a waiter...)
pthread_cond_signal(foo_cond) ;
pthread_mutex_unlock(foo_mutex) ;
NB: the standard explicitly allows pthread_cond_signal() to start one, some or all waiters... hence the while(...) loop in the waiter... and the waiter that "claims" the signal needs to update the state so that any other threads will loop in that while (...)