Method value

include/process/metrics/timer.hpp:45–58

      data(new Data()) {}

  Future<double> value() const override
  {
    Future<double> value;

    synchronized (data->lock) {
      if (data->lastValue.isSome()) {
        value = data->lastValue.get();
      } else {
        value = Failure("No value");
      }
    }

    return value;
  }

  // Start the Timer.
  void start()