Construct a signal set and add three signals.
basic_signal_set( const executor_type & ex, int signal_number_1, int signal_number_2, int signal_number_3);
This constructor creates a signal set and registers for three signals.
The I/O executor that the signal set will use, by default, to dispatch handlers for any asynchronous operations performed on the signal set.
The first signal number to be added.
The second signal number to be added.
The third signal number to be added.
This constructor is equivalent to performing:
boost::asio::signal_set signals(ex); signals.add(signal_number_1); signals.add(signal_number_2); signals.add(signal_number_3);