code: public static CompletionStage<ReloadableSparkeyReader> fromLogFile(File logFile, ExecutorService executorService) {
      ReloadableSparkeyReader reader = new ReloadableSparkeyReader(executorService);
      return reader.load(logFile);
    }
docs: Creates a new {@link ReloadableSparkeyReader} from a log file.
  
  @param logFile The log file to start with.
  @param executorService An executor service that is used to run reload tasks on.
  @return A future that resolves to the sparkey reader once it has loaded the log file.