void repairConnectionsForUpdate()

in cpp/src/hnswalg.h [1197:1268]
62 lines of code
13 McCabe index (conditional complexity)

  void repairConnectionsForUpdate(const data_t *dataPoint,
                                  tableint entryPointInternalId,
                                  tableint dataPointInternalId,
                                  int dataPointLevel, int maxLevel) {
    tableint currObj = entryPointInternalId;
    if (dataPointLevel < maxLevel) {
      dist_t curdist = fstdistfunc_(dataPoint, getDataByInternalId(currObj),
                                    dist_func_param_);
      for (int level = maxLevel; level > dataPointLevel; level--) {
        bool changed = true;
        while (changed) {
          changed = false;
          unsigned int *data;
          std::unique_lock<std::mutex> lock(link_list_locks_[currObj]);
          data = get_linklist_at_level(currObj, level);
          int size = getListCount(data);
          tableint *datal = (tableint *)(data + 1);
          for (int i = 0; i < size; i++) {
            tableint cand = datal[i];
            dist_t d = fstdistfunc_(dataPoint, getDataByInternalId(cand),
                                    dist_func_param_);
            if (d < curdist) {
              curdist = d;
              currObj = cand;
              changed = true;
            }
          }
        }
      }
    }

    if (dataPointLevel > maxLevel)
      throw std::runtime_error(
          "Level of item to be updated cannot be bigger than max level");

    for (int level = dataPointLevel; level >= 0; level--) {
      std::priority_queue<std::pair<dist_t, tableint>,
                          std::vector<std::pair<dist_t, tableint>>,
                          CompareByFirst>
          topCandidates = searchBaseLayer(currObj, dataPoint, level);

      std::priority_queue<std::pair<dist_t, tableint>,
                          std::vector<std::pair<dist_t, tableint>>,
                          CompareByFirst>
          filteredTopCandidates;
      while (topCandidates.size() > 0) {
        if (topCandidates.top().second != dataPointInternalId)
          filteredTopCandidates.push(topCandidates.top());

        topCandidates.pop();
      }

      // Since element_levels_ is being used to get `dataPointLevel`, there
      // could be cases where `topCandidates` could just contains entry point
      // itself. To prevent self loops, the `topCandidates` is filtered and thus
      // can be empty.
      if (filteredTopCandidates.size() > 0) {
        bool epDeleted = isMarkedDeleted(entryPointInternalId);
        if (epDeleted) {
          filteredTopCandidates.emplace(
              fstdistfunc_(dataPoint, getDataByInternalId(entryPointInternalId),
                           dist_func_param_),
              entryPointInternalId);
          if (filteredTopCandidates.size() > ef_construction_)
            filteredTopCandidates.pop();
        }

        currObj = mutuallyConnectNewElement(dataPoint, dataPointInternalId,
                                            filteredTopCandidates, level, true);
      }
    }
  }