void getNeighborsByHeuristic2()

in cpp/src/hnswalg.h [397:440]

• 40 lines of code
• 9 McCabe index (conditional complexity)

  void getNeighborsByHeuristic2(
      std::priority_queue<std::pair<dist_t, tableint>,
                          std::vector<std::pair<dist_t, tableint>>,
                          CompareByFirst> &top_candidates,
      const size_t M) {
    if (top_candidates.size() < M) {
      return;
    }

    std::priority_queue<std::pair<dist_t, tableint>> queue_closest;
    std::vector<std::pair<dist_t, tableint>> return_list;
    while (top_candidates.size() > 0) {
      queue_closest.emplace(-top_candidates.top().first,
                            top_candidates.top().second);
      top_candidates.pop();
    }

    while (queue_closest.size()) {
      if (return_list.size() >= M)
        break;
      std::pair<dist_t, tableint> curent_pair = queue_closest.top();
      dist_t dist_to_query = -curent_pair.first;
      queue_closest.pop();
      bool good = true;

      for (std::pair<dist_t, tableint> second_pair : return_list) {
        dist_t curdist = fstdistfunc_(getDataByInternalId(second_pair.second),
                                      getDataByInternalId(curent_pair.second),
                                      dist_func_param_);
        ;
        if (curdist < dist_to_query) {
          good = false;
          break;
        }
      }
      if (good) {
        return_list.push_back(curent_pair);
      }
    }

    for (std::pair<dist_t, tableint> curent_pair : return_list) {
      top_candidates.emplace(-curent_pair.first, curent_pair.second);
    }
  }