Method update

performance-tests/bench/common/PropertyStatBlock.cpp:278–316

}

void PropertyStatBlock::update(double value, const Builder::TimeStamp& time)
{
  const double prev_mean = mean_->value.double_prop();
  const double prev_var_x_sample_count = var_x_sample_count_->value.double_prop();

  size_t next_median_buffer_index = static_cast<size_t>(sample_count_->value.ull_prop() % median_buffer_.size());

  if (sample_count_->value.ull_prop() < median_buffer_.size()) {
    median_sample_count_->value.ull_prop(median_sample_count_->value.ull_prop() + 1);
  }
  sample_count_->value.ull_prop(sample_count_->value.ull_prop() + 1);

  if (value < min_->value.double_prop()) {
    min_->value.double_prop(value);
  }

  if (max_->value.double_prop() < value) {
    max_->value.double_prop(value);
  }

  // sample_count should always be >= 1 by this point
  OPENDDS_ASSERT(sample_count_->value.ull_prop() >= 1);

  if (sample_count_->value.ull_prop() == 1) {
    mean_->value.double_prop(value);
    // variance remains 0 until we have 2 samples, so don't touch var_x_sample_count_ here
  } else {
    // Incremental mean calculation (doesn't require storing all the data)
    mean_->value.double_prop(prev_mean + ((value - prev_mean) / static_cast<double>(sample_count_->value.ull_prop())));
    // Incremental (variance * sample_count) calculation (doesn't require storing all the data, can be used to easily find variance / standard deviation)
    var_x_sample_count_->value.double_prop(prev_var_x_sample_count + ((value - prev_mean) * (value - mean_->value.double_prop())));
  }

  median_buffer_[next_median_buffer_index] = value;

  if (timestamp_buffer_.size()) {
    timestamp_buffer_[next_median_buffer_index] = time == Builder::ZERO ? Builder::get_sys_time() : time;
  }
}

void PropertyStatBlock::finalize()
{