Method poll

cpp/src/arrow/ipc/reader.cc:1618–1628

\brief Capture a copy of the current counters

    /// \brief Capture a copy of the current counters
    ReadStats poll() const {
      ReadStats stats;
      stats.num_messages = num_messages.load(std::memory_order_relaxed);
      stats.num_record_batches = num_record_batches.load(std::memory_order_relaxed);
      stats.num_dictionary_batches =
          num_dictionary_batches.load(std::memory_order_relaxed);
      stats.num_dictionary_deltas = num_dictionary_deltas.load(std::memory_order_relaxed);
      stats.num_replaced_dictionaries =
          num_replaced_dictionaries.load(std::memory_order_relaxed);
      return stats;
    }
  };

  Result<FileBlock> GetRecordBatchBlock(int i) const {