# subroutine name: LOG
# Appends message to log file. Before message timestamp is added.
#
# Global variables used:
#	$no_flock - disable flock or not
sub LOG {
	my ($filename,$message)=@_;
	mkdir("logs", 0777);
	my $existed=-e "logs/$filename.log";
	if (open(LOGFILE, ">>logs/$filename.log")) {
		my $txt=localtime()."|$message\n";
		unless ($no_flock) {
			# Exclusive locking
			flock(LOGFILE, 2) ;
			# In case someone appended while we
			# were waiting, seek to EOF
			seek(LOGFILE, 0, 2);
		}
		print LOGFILE $txt;
		# unlock file
		flock(LOGFILE, 8) unless ($no_flock);
		close(LOGFILE);
		chmod(0666, "logs/$filename.log") unless ($existed);
	}
}