sub loadSession($$){
    my ($dbhandle,$cgi) = @_;
    my $session = CGI::Session->load("driver:MySQL", $cgi, {Handle=>$dbhandle});
    if ( $session->is_expired && $session->param("logged_in")) {
        displayLoginPage("Your session has expired, please log in again");
        exit(0);
    }elsif ( $session->is_empty) {
        $session = $session->new("driver:MySQL", $cgi, {Handle=>$dbhandle});
        $session->expire('+1m');
        print $session->header();
        displayLoginPage(undef);
        exit(0);
    }else{
        print $session->header();
    }
    return $session;
}

sub logout($$){
    my($cgi,$dbhandler) = @_;
    my $session = CGI::Session->load("driver:MySQL", $cgi, {Handle=>$dbhandler}) or die CGI::Session->errstr;
    $session->clear();
    $session->delete();
}