template< typename SignalHandler = DEFAULT> DEDUCED async_wait( SignalHandler && handler = DEFAULT);
This function may be used to initiate an asynchronous wait against the signal set. It always returns immediately.
For each call to
async_wait(), the supplied handler will be
called exactly once. The handler will be called when:
The handler to be called when the signal occurs. Copies will be made of the handler as required. The function signature of the handler must be:
void handler( const boost::system::error_code& error, // Result of operation. int signal_number // Indicates which signal occurred. );
Regardless of whether the asynchronous operation completes immediately
or not, the handler will not be invoked from within this function.
On immediate completion, invocation of the handler will be performed
in a manner equivalent to using