Method CheckFetch

tensorflow/core/common_runtime/direct_session.cc:1825–1884

}

Status DirectSession::CheckFetch(const NamedTensorList& feeds,
                                 const std::vector<string>& fetches,
                                 const ExecutorsAndKeys* executors_and_keys,
                                 const RunState* run_state) {
  const Graph* graph = executors_and_keys->graph.get();
  const NameNodeMap* name_to_node = &executors_and_keys->name_to_node;

  // Build the set of pending feeds that we haven't seen.
  std::unordered_set<TensorId, TensorId::Hasher> pending_feeds;
  {
    mutex_lock l(executor_lock_);
    for (const auto& input : run_state->pending_inputs) {
      // Skip if the feed has already been fed.
      if (input.second) continue;
      TensorId id(ParseTensorName(input.first));
      auto it = name_to_node->find(id.first);
      if (it == name_to_node->end()) {
        return errors::NotFound("Feed ", input.first, ": not found");
      }
      pending_feeds.insert(id);
    }
  }
  for (const auto& it : feeds) {
    TensorId id(ParseTensorName(it.first));
    pending_feeds.erase(id);
  }

  // Initialize the stack with the fetch nodes.
  std::vector<const Node*> stack;
  for (const string& fetch : fetches) {
    TensorId id(ParseTensorName(fetch));
    auto it = name_to_node->find(id.first);
    if (it == name_to_node->end()) {
      return errors::NotFound("Fetch ", fetch, ": not found");
    }
    stack.push_back(it->second);
  }

  // Any tensor needed for fetches can't be in pending_feeds.
  std::vector<bool> visited(graph->num_node_ids(), false);
  while (!stack.empty()) {
    const Node* n = stack.back();
    stack.pop_back();

    for (const Edge* in_edge : n->in_edges()) {
      const Node* in_node = in_edge->src();
      if (pending_feeds.count({in_node->name(), in_edge->src_output()}) > 0) {
        return errors::InvalidArgument("Fetch ", in_node->name(), ":",
                                       in_edge->src_output(),
                                       " can't be computed from the feeds"
                                       " that have been fed so far.");
      }
      if (!visited[in_node->id()]) {
        visited[in_node->id()] = true;
        stack.push_back(in_node);
      }
    }
  }