Function TF_FinishWhileHelper

tensorflow/c/c_api.cc:1973–2041

TODO(skyewm): make nodes in while loop unfetchable like in Python version

// TODO(skyewm): make nodes in while loop unfetchable like in Python version
void TF_FinishWhileHelper(const TF_WhileParams* params, TF_Status* status,
                          TF_Output* outputs) {
  if (!ValidateInputWhileParams(*params, status)) return;

  TF_Graph* parent = params->cond_graph->parent;
  TF_Output* parent_inputs = params->cond_graph->parent_inputs;
  int num_loop_vars = params->ninputs;

  mutex_lock l(parent->mu);

  // 'cond_fn' copies the cond graph into the parent graph.
  tensorflow::ops::CondGraphBuilderFn cond_fn =
      [params, parent](const tensorflow::Scope& scope,
                       const std::vector<tensorflow::Output>& inputs,
                       tensorflow::Output* output) {
        DCHECK_EQ(scope.graph(), &parent->graph);
        std::vector<tensorflow::Output> cond_output;
        TF_RETURN_IF_ERROR(CopyGraph(
            &params->cond_graph->graph, &parent->graph, &parent->refiner,
            params->cond_inputs, inputs, scope.impl()->name(),
            scope.impl()->control_deps(), &params->cond_output,
            /* nreturn_nodes */ 1, &cond_output));
        *output = cond_output[0];
        return Status::OK();
      };

  // 'body_fn' copies the body graph into the parent graph.
  tensorflow::ops::BodyGraphBuilderFn body_fn =
      [params, parent, num_loop_vars](
          const tensorflow::Scope& scope,
          const std::vector<tensorflow::Output>& inputs,
          std::vector<tensorflow::Output>* outputs) {
        DCHECK_EQ(scope.graph(), &parent->graph);
        TF_RETURN_IF_ERROR(
            CopyGraph(&params->body_graph->graph, &parent->graph,
                      &parent->refiner, params->body_inputs, inputs,
                      scope.impl()->name(), scope.impl()->control_deps(),
                      params->body_outputs, num_loop_vars, outputs));
        return Status::OK();
      };

  // Create the while loop using an internal scope.
  tensorflow::Scope scope =
      NewInternalScope(&parent->graph, &status->status, &parent->refiner)
          .NewSubScope(params->name);

  const int first_new_node_id = parent->graph.num_node_ids();

  tensorflow::OutputList loop_outputs;
  status->status = tensorflow::ops::BuildWhileLoop(
      scope, OutputsFromTFOutputs(parent_inputs, num_loop_vars), cond_fn,
      body_fn, params->name, &loop_outputs);

  // Update name_map with newly-created ops.
  // TODO(skyewm): right now BuildWhileLoop() may alter the graph if it returns
  // a bad status. Once we fix this, we may want to return early instead of
  // executing the following code.
  for (int i = first_new_node_id; i < parent->graph.num_node_ids(); ++i) {