Method StartReader

cpp/src/arrow/io/file_benchmark.cc:71–75

 public:
  static std::shared_ptr<BackgroundReader> StartReader(int fd) {
    std::shared_ptr<BackgroundReader> reader(new BackgroundReader(fd));
    reader->worker_.reset(new std::thread([=] { reader->LoopReading(); }));
    return reader;
  }
  void Stop() { ARROW_CHECK(SetEvent(event_)); }
  void Join() { worker_->join(); }