587 sub run_on_wait {
    588   my ($s,$code, $period)=@_;
    589 
    590   $s->{on_wait}=$code;
    591   $s->{on_wait_period} = $period;
    592 }
    593 
    594 sub on_wait {
    595   my ($s)=@_;
    596 
    597   if(ref($s->{on_wait}) eq 'CODE') {
    598     $s->{on_wait}->();
    599     if (defined $s->{on_wait_period}) {
    600         local $SIG{CHLD} = sub { } if ! defined $SIG{CHLD};
    601         select undef, undef, undef, $s->{on_wait_period}
    602     };
    603   };
    604 };