Signals that the calling thread has arrived at the synchronization point without blocking. The calling thread is removed from the set of participating threads, and the count of participating threads is thus decreased by one.
Either the calling thread is one of the first N
threads to arrive at
*this since construction, where
N is the value of the
parameter to the constructor, or the calling thread is already
one of the set of participating threads for
Signal that the calling thread has arrived at the barrier. If this
is the last of the participating threads to arrive then all threads
are unblocked and the barrier is reset. The calling thread is removed
from the set of participating threads.