Method instance

cpp/src/arrow/util/cancel.cc:212–219

  }

  static SignalStopState* instance() {
    static std::shared_ptr<SignalStopState> instance = []() {
      auto ptr = std::make_shared<SignalStopState>();
      ptr->Init();
      return ptr;
    }();
    return instance.get();
  }

 private:
  void SpawnSignalReceivingThread() {