# subroutine name: writehash
# Input: filename, hash reference
# Writes hash to file in format: <key>\t<value>
#
# Global variables used:
#	$no_flock - disable flock or not
sub writehash {

	my($datafile,$r_rows) = @_;
	GetFileLock("$datafile.lock");

	use Fcntl qw( O_RDWR O_WRONLY O_CREAT O_TRUNC );
	local *DATA;
	if (sysopen(DATA, $datafile, &O_WRONLY | &O_CREAT)) {
		flock(DATA, 2) unless ($no_flock);
		truncate(DATA, 0) or die "Can't truncate $datafile. Reason: $!";
		foreach (keys %$r_rows) {
			print DATA safe_tbl($_)."\t".safe_tbl(${$r_rows}{$_})."\n";
		}
		flock(DATA, 8) unless ($no_flock);
		close(DATA);
		chmod(0666,$datafile);
		ReleaseFileLock("$datafile.lock");
	} else {
		ReleaseFileLock("$datafile.lock");
		die("Error in subroutine writehash: Can't open $datafile. Reason: $!");
	}
}