sub store {
    my ($self, $sid, $options, $data) = @_;   

    my $dbh = $self->MySQL_dbh($options);
    my $lck_status = $dbh->selectrow_array(qq|SELECT GET_LOCK("$sid", 10)|);
    unless ( $lck_status == 1 ) {
        $self->error("Couldn't acquire lock on id '$sid'. Lock status: $lck_status");
        return undef;
    }

    $dbh->do(qq|REPLACE INTO $TABLE_NAME (id, expires, a_session) VALUES(?,FROM_UNIXTIME(?),?)|, 
                undef, $sid, $self->expire(), $self->freeze($data));
    
    return $dbh->selectrow_array(qq|SELECT RELEASE_LOCK("$sid")|);
}