private void storeState() throws IOException {
Packet controlData = controlFile.getControlData();
if( controlData.remaining() == 0 )
return;
DataOutput data = new DataOutputStream(new PacketOutputStream(controlData));
data.writeInt(lastLogFileId);
data.writeBoolean(lastMark!=null);
if( lastMark!=null )
lastMark.writeToDataOutput(data);