private long _getRawBits(StatisticDescriptorImpl descriptor) {
    switch (descriptor.getTypeCode()) {
      case StatisticDescriptorImpl.LONG:
        return _getLong(descriptor.getId());
      case StatisticDescriptorImpl.DOUBLE:
        return Double.doubleToRawLongBits(_getDouble(descriptor.getId()));
      default:
        throw new RuntimeException(
            String.format("unexpected stat descriptor type code: %s",
                descriptor.getTypeCode()));
    }
  }
Returns the bits that represent the raw value of the specified statistic descriptor.
geode-core/src/main/java/org/apache/geode/internal/statistics/StatisticsImpl.java