Class WholeIpcFileRecordBatchGenerator

cpp/src/arrow/ipc/reader.cc:1305–1336

A generator of record batches. All batches are yielded in order.

///
/// All batches are yielded in order.
class WholeIpcFileRecordBatchGenerator {
 public:
  using Item = std::shared_ptr<RecordBatch>;

  explicit WholeIpcFileRecordBatchGenerator(
      std::shared_ptr<RecordBatchFileReaderImpl> state,
      std::shared_ptr<io::internal::ReadRangeCache> cached_source,
      const io::IOContext& io_context, arrow::internal::Executor* executor)
      : state_(std::move(state)),
        cached_source_(std::move(cached_source)),
        io_context_(io_context),
        executor_(executor),
        index_(0) {}

  Future<Item> operator()();
  Future<std::shared_ptr<Message>> ReadBlock(const FileBlock& block);

  static Status ReadDictionaries(
      RecordBatchFileReaderImpl* state,
      std::vector<std::shared_ptr<Message>> dictionary_messages);
  static Result<std::shared_ptr<RecordBatch>> ReadRecordBatch(
      RecordBatchFileReaderImpl* state, Message* message);

 private:
  std::shared_ptr<RecordBatchFileReaderImpl> state_;
  std::shared_ptr<io::internal::ReadRangeCache> cached_source_;
  io::IOContext io_context_;
  arrow::internal::Executor* executor_;
  int index_;
  // Odd Future type, but this lets us use All() easily
  Future<> read_dictionaries_;
};

/// A generator of record batches for use when reading
/// a subset of columns from the file.