Method ReadAt

cpp/src/arrow/filesystem/gcsfs.cc:293–300

  // @name RandomAccessFile
  Result<int64_t> GetSize() override { return metadata_.size(); }
  Result<int64_t> ReadAt(int64_t position, int64_t nbytes, void* out) override {
    if (closed()) return Status::Invalid("Cannot read from closed file");
    std::shared_ptr<io::InputStream> stream;
    ARROW_ASSIGN_OR_RAISE(stream, factory_(gcs::Generation(metadata_.generation()),
                                           gcs::ReadRange(position, position + nbytes),
                                           gcs::ReadFromOffset()));
    return stream->Read(nbytes, out);
  }
  Result<std::shared_ptr<Buffer>> ReadAt(int64_t position, int64_t nbytes) override {
    if (closed()) return Status::Invalid("Cannot read from closed file");
    std::shared_ptr<io::InputStream> stream;