Method InferFromGraphViewT

tensorflow/core/grappler/utils/frame.cc:31–142

template <typename GraphViewT>
inline Status FrameView::InferFromGraphViewT(const GraphViewT& graph_view) {
  if (is_inferred_) {
    return errors::Internal("FrameView was already inferred from the graph");
  }
  is_inferred_ = true;

  std::deque<int> ready_node_indices;

  // All nodes without inputs are automatically added to the ready queue.
  for (const auto& node : graph_view.GetNodes()) {
    if (node.NumRegularFanins() + node.NumControllingFanins() == 0) {
      ready_node_indices.push_back(node.node_index());
      node_to_frames_[node.node()] = node_has_no_frames_;
    }
  }

  const auto* graph = graph_view.graph();

  // We assign unique int id to each frame, and use this map to track what
  // frames we've already seen in the graph.
  absl::flat_hash_map<string, int> frame_name_to_id;

  auto process_fanout = [this, graph](
                            absl::flat_hash_map<string, int>* frame_name_to_id,
                            std::deque<int>* ready_node_indices,
                            const NodeDef* ready_node, int fanout_node_index) {
    const NodeDef* fanout_node = &graph->node(fanout_node_index);
    if (!node_to_frames_.contains(fanout_node)) {
      // If we have never seen this node before, we add all frames from the
      // incoming node (and pop/push frames if coming from Exit/Enter nodes).
      std::vector<int> frame_ids = node_to_frames_[ready_node];

      if (IsExit(*ready_node)) {
        frame_ids.pop_back();
      }

      if (IsEnter(*fanout_node)) {
        const AttrValue* frame_name_attr =
            AttrSlice(*fanout_node).Find("frame_name");

        if (!frame_name_attr) {
          return errors::InvalidArgument(
              "Missing frame name for the Enter node: ",
              SummarizeNodeDef(*fanout_node));
        }

        const string& frame_name = frame_name_attr->s();
        int frame_id;

        if (frame_name_to_id->contains(frame_name)) {
          frame_id = (*frame_name_to_id)[frame_name];
        } else {
          frame_id = static_cast<int>(frame_name_to_id->size());
          (*frame_name_to_id)[frame_name] = frame_id;
        }

        frame_ids.push_back(frame_id);
      }