void resizeIndex()

in cpp/src/hnswalg.h [654:690]

• 28 lines of code
• 5 McCabe index (conditional complexity)

  void resizeIndex(size_t new_max_elements) {
    if (search_only_)
      throw std::runtime_error(
          "resizeIndex is not supported in search only mode");
    std::unique_lock<std::shared_mutex> lock(resizeLock);

    if (new_max_elements < cur_element_count)
      throw IndexCannotBeShrunkError(
          "Cannot resize to " + std::to_string(new_max_elements) +
          " elements, as this index already contains " +
          std::to_string(cur_element_count) + " elements.");

    delete visited_list_pool_;
    visited_list_pool_ = new VisitedListPool(1, new_max_elements);

    element_levels_.resize(new_max_elements);

    std::vector<std::mutex>(new_max_elements).swap(link_list_locks_);

    // Reallocate base layer
    char *data_level0_memory_new = (char *)realloc(
        data_level0_memory_, new_max_elements * size_data_per_element_);
    if (data_level0_memory_new == nullptr)
      throw std::runtime_error(
          "Not enough memory: resizeIndex failed to allocate base layer");
    data_level0_memory_ = data_level0_memory_new;

    // Reallocate all other layers
    char **linkLists_new =
        (char **)realloc(linkLists_, sizeof(void *) * new_max_elements);
    if (linkLists_new == nullptr)
      throw std::runtime_error(
          "Not enough memory: resizeIndex failed to allocate other layers");
    linkLists_ = linkLists_new;

    max_elements_ = new_max_elements;
  }