std::latch

Now, let us have a closer look at the interface of a std::latch.

Member function	Description
lat.count_down(upd = 1)	Atomically decrements the counter by upd without blocking the caller.
lat.try_wait()	Returns true if counter == 0.
lat.wait()	Returns immediately if counter == 0. If not blocks until counter == 0.
lat.arrive_and_wait(upd = 1)	Equivalent to count_down(upd); wait();.