Inherited from basic_socket.
Sets the non-blocking mode of the socket.
void non_blocking( bool mode);
true, the socket's synchronous operations will
asio::error::would_block if they are unable
to perform the requested operation immediately. If
synchronous operations will block until complete.
Thrown on failure.
The non-blocking mode has no effect on the behaviour of asynchronous
operations. Asynchronous operations will never fail with the error