use Fcntl qw(:flock SEEK_END);

# ---------------------------------------
# sub logmsg
# ---------------------------------------
sub logmsg {
  my $now = time;
  my $msec = int( ( $now - int($now) ) * 1000 );
  my ( $sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdst ) = localtime(time);

  sub lock {
    flock( LOG, LOCK_EX );
    # and, in case someone appended
    # while we were waiting...
    seek( LOG, 0, SEEK_END );
  }

  sub unlock {
    flock( LOG, LOCK_UN );
  }

  open LOG, ">> $logFilename";
  lock();
  printf LOG "%02d:%02d:%02d:%03d %s\r\n", $hour, $min, $sec, $msec, @_;
  unlock();

  close(LOG);
}