Method PrepareForContentsWrite

cpp/src/arrow/csv/writer.cc:581–591

 private:
  Status PrepareForContentsWrite() {
    // Only called once, as part of initialization
    if (data_buffer_ == nullptr) {
      ARROW_ASSIGN_OR_RAISE(
          data_buffer_,
          AllocateResizableBuffer(
              options_.batch_size * schema_->num_fields() * kColumnSizeGuess,
              options_.io_context.pool()));
    }
    return Status::OK();
  }

  // GH-36889: Flush buffer to sink and clear it to avoid stale content
  // being written again if the next batch is empty.