void Coordinator::WaitForStop() {
  mutex_lock l(mu_);
  while (!should_stop_) {
    wait_for_stop_.wait(l);
  }
}

Status Coordinator::ExportCostGraph(CostGraphDef* cost_graph) const {
  mutex_lock l(runners_lock_);
  for (auto& t : runners_) {
    Status s = t->ExportCostGraph(cost_graph);
    if (!s.ok()) {
      return s;
    }
  }
  return absl::OkStatus();
}

    if (coord_) {
      coord_->RequestStop().IgnoreError();
    }
  }
}

Status QueueRunner::GetStatus() {
  mutex_lock l(mu_);
  return status_;
}

Status QueueRunner::ExportCostGraph(CostGraphDef* cost_graph) const {
  if (!cg_mu_) {
    return Status(absl::StatusCode::kFailedPrecondition,
                  "This QueueRunner doesn't collect a cost graph.");
  }
  mutex_lock l(*cg_mu_);