void var_opt_sketch::update()

in sampling/include/var_opt_sketch_impl.hpp [774:810]

• 25 lines of code
• 13 McCabe index (conditional complexity)

void var_opt_sketch<T, A>::update(O&& item, double weight, bool mark) {
  if (weight < 0.0 || std::isnan(weight) || std::isinf(weight)) {
    throw std::invalid_argument("Item weights must be nonnegative and finite. Found: "
                                + std::to_string(weight));
  } else if (weight == 0.0) {
    return;
  }
  ++n_;

  if (r_ == 0) {
    // exact mode
    update_warmup_phase(std::forward<O>(item), weight, mark);
  } else {
    // sketch is in estimation mode so we can make the following check,
    // although very conservative to check every time
    if ((h_ != 0) && (peek_min() < get_tau()))
      throw std::logic_error("sketch not in valid estimation mode");

    // what tau would be if deletion candidates turn out to be R plus the new item
    // note: (r_ + 1) - 1 is intentional
    const double hypothetical_tau = (weight + total_wt_r_) / ((r_ + 1) - 1);

    // is new item's turn to be considered for reservoir?
    const double condition1 = (h_ == 0) || (weight <= peek_min());

    // is new item light enough for reservoir?
    const double condition2 = weight < hypothetical_tau;
  
    if (condition1 && condition2) {
      update_light(std::forward<O>(item), weight, mark);
    } else if (r_ == 1) {
      update_heavy_r_eq1(std::forward<O>(item), weight, mark);
    } else {
      update_heavy_general(std::forward<O>(item), weight, mark);
    }
  }
}