Field Configuration loading

FieldsConfigurationProvider.java

public class FieldsConfigurationProvider  {

    private Logger logger = LoggerFactory.getLogger(FieldsConfigurationProvider.class);
    private Long lastUpdateTime;
    private FieldsConfiguration config;

    private static FieldsConfigurationProvider instance = null;
    public static String bucketName;
    public static  String filePath;
    private static long fieldsConfigLoadInterval;
    private final static Object lock = new Object();

    public static FieldsConfigurationProvider getInstance() {
        if (instance == null) {
            synchronized (lock) {
                if (instance == null) {
                    instance = new FieldsConfigurationProvider();
                }
            }
        }
        return instance;
    }
    private FieldsConfigurationProvider(){
        config = loadConfig(filePath);
        watch();
    }

    public static void init(String bucketName, long fieldsConfigLoadInterval, String filePath ) {

        FieldsConfigurationProvider.bucketName = bucketName;
        FieldsConfigurationProvider.fieldsConfigLoadInterval = fieldsConfigLoadInterval;
        FieldsConfigurationProvider.filePath=filePath;
    }


 
    private void watch() {
        new Thread(() -> {

            logger.info("start watching for bucket changes....");

            Storage storage = StorageOptions.getDefaultInstance().getService();
            Bucket bucket = storage.get(bucketName);

            while(true) {
                logger.debug("Checking for new fields configuration in the bucket");
                Blob blob = bucket.get(filePath);
                long currentTime = blob.getUpdateTime();
                if (currentTime > lastUpdateTime) {
                    logger.info("Found new fields configuration in the bucket");
                    config = loadConfig(filePath);
                } else {
                    logger.debug("Didn't find new fields configuration in bucket");
                }
                try {
                    Thread.sleep(fieldsConfigLoadInterval);
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                }
            }
        }).start();
    }



    private FieldsConfiguration loadConfig(String path) {
        try {
            ObjectMapper mapper = new ObjectMapper();

            logger.info("Reading fields configuration from gs://" + bucketName + "/" + path);

            Storage storage = StorageOptions.getDefaultInstance().getService();
            Bucket bucket = storage.get(bucketName);
            Blob blob = bucket.get(path);
            lastUpdateTime = blob.getUpdateTime();

            ByteArrayInputStream byteStream = new ByteArrayInputStream(blob.getContent());

            return mapper.readValue(byteStream, FieldsConfiguration.class);
        } catch (IOException e) {
            logger.error("Unable reading fields configuration file", e);
        }
        return null;
    }

    public FieldsConfiguration getConfig() {
        return config;
    }
   

}