sub set_timer($$;)
{
    my $self     = shift;
    my $id       = shift;
    my $callback = shift;
    my $time     = shift || 1;

    $self->fatalerror(
        "add_timer(): callback is no CODE reference"
    ) unless defined $callback and ref $callback eq 'CODE';

    $self->fatalerror(
	"add_timer(): id is not set"
    ) unless defined $id;

    my $config = {
        -time     => $time,
        -callback => $callback,
        -enabled  => 1,
        -lastrun  => time(),
    };
    $self->{-timers}->{$id} = $config;

    $self->set_read_timeout;

    return $self;
}