public synchronized void writeString(String string) {
        Path logPath = Paths.get(ServiceOptions.getInstance().getCacheStorePath(), LOG_FILE_NAME);
        byte data[] = (string+"\n").getBytes();
        try (OutputStream out = new BufferedOutputStream(
                Files.newOutputStream(logPath, StandardOpenOption.CREATE, StandardOpenOption.APPEND))) {
            out.write(data, 0, data.length);
        } catch (IOException ioe) {
            LOGGER.error("", ioe);
        }
    }