sub flock_lock {
    my ($fh, $excl, $wait) = @_;
    my $flag = $excl ? $flock_LOCK_EX : $flock_LOCK_SH;

    if ($wait) {
	my $trylimit = $Vend::Cfg->{Limit}{file_lock_retries} || 5;
	my $failedcount;
        while (
                ! flock($fh, $flag)
                    and
                $failedcount < $trylimit
               )
        {
           $failedcount++;
           select(undef,undef,undef,0.05 * $failedcount);
        }
        die "Could not lock file after $trylimit tries: $!\n" if ($failedcount == $trylimit);
        return 1;
    }
    else {
        if (! flock($fh, $flag | $flock_LOCK_NB)) {
            if ($!{EAGAIN} or $!{EWOULDBLOCK}) {
				return 0;
            }
            else {
                die "Could not lock file: $!\n";
            }
        }
        return 1;
    }
}