357 sub run_on_wait { my ($s,$code, $period)=@_;
    358   $s->{on_wait}=$code;
    359   $s->{on_wait_period} = $period;
    360 }
    361 
    362 sub on_wait { my ($s)=@_;
    363   if(ref($s->{on_wait}) eq 'CODE') {
    364     $s->{on_wait}->();
    365     if (defined $s->{on_wait_period}) {
    366         local $SIG{CHLD} = sub { } if ! defined $SIG{CHLD};
    367         select undef, undef, undef, $s->{on_wait_period}
    368     };
    369   };
    370 };