Method SpawnAdds

cpp/src/arrow/util/thread_pool_test.cc:517–520

  }

  void SpawnAdds(ThreadPool* pool, int nadds, AddTaskFunc add_func,
                 StopToken stop_token = StopToken::Unstoppable()) {
    DoSpawnAdds(pool, nadds, std::move(add_func), std::move(stop_token));
  }

  void SpawnAddsAndCancel(ThreadPool* pool, int nadds, AddTaskFunc add_func,
                          StopSource* stop_source) {