bool build()

in src/annoylib.h [1037:1078]

• 30 lines of code
• 7 McCabe index (conditional complexity)

  bool build(int q, int n_threads=-1, char** error=NULL) {
    if (_loaded) {
      set_error_from_string(error, "You can't build a loaded index");
      return false;
    }

    if (_built) {
      set_error_from_string(error, "You can't build a built index");
      return false;
    }

    D::template preprocess<T, S, Node>(_nodes, _s, _n_items, _f);

    _n_nodes = _n_items;

    ThreadedBuildPolicy::template build<S, T>(this, q, n_threads);

    // Also, copy the roots into the last segment of the array
    // This way we can load them faster without reading the whole file
    _allocate_size(_n_nodes + (S)_roots.size());
    for (size_t i = 0; i < _roots.size(); i++)
      memcpy(_get(_n_nodes + (S)i), _get(_roots[i]), _s);
    _n_nodes += _roots.size();

    if (_verbose) annoylib_showUpdate("has %d nodes\n", _n_nodes);
    
    if (_on_disk) {
      if (!remap_memory_and_truncate(&_nodes, _fd,
          static_cast<size_t>(_s) * static_cast<size_t>(_nodes_size),
          static_cast<size_t>(_s) * static_cast<size_t>(_n_nodes))) {
        // TODO: this probably creates an index in a corrupt state... not sure what to do
        set_error_from_errno(error, "Unable to truncate");
        return false;
      }
      _nodes_size = _n_nodes;
    }

    D::template postprocess<T, S, Node>(_nodes, _s, _n_items, _f);

    _built = true;
    return true;
  }