@Override
  public void completeBootstrap() {
    File bootstrapFile = new File(dataDir, config.storeBootstrapInProgressFile);
    try {
      // the method will check if file exists or not
      Utils.deleteFileOrDirectory(bootstrapFile);
    } catch (IOException e) {
      // if deletion fails, we log here without throwing exception. Next time when server restarts, the store should
      // complete BOOTSTRAP -> STANDBY quickly and attempt to delete this again.
      logger.error("Failed to delete {}", bootstrapFile.getName(), e);
    }
  }
@return The number of byte been written to log
ambry-store/src/main/java/com/github/ambry/store/BlobStore.java