Function WriteMessage

cpp/src/arrow/ipc/message.cc:603–634

}

Status WriteMessage(const Buffer& message, const IpcWriteOptions& options,
                    io::OutputStream* file, int32_t* message_length) {
  const int32_t prefix_size = options.write_legacy_ipc_format ? 4 : 8;
  const int32_t flatbuffer_size = static_cast<int32_t>(message.size());

  int32_t padded_message_length = static_cast<int32_t>(
      PaddedLength(flatbuffer_size + prefix_size, options.alignment));

  int32_t padding = padded_message_length - flatbuffer_size - prefix_size;

  // The returned message size includes the length prefix, the flatbuffer,
  // plus padding
  *message_length = padded_message_length;

  // ARROW-6314: Write continuation / padding token
  if (!options.write_legacy_ipc_format) {
    RETURN_NOT_OK(file->Write(&internal::kIpcContinuationToken, sizeof(int32_t)));
  }

  // Write the flatbuffer size prefix including padding in little endian
  int32_t padded_flatbuffer_size =
      bit_util::ToLittleEndian(padded_message_length - prefix_size);
  RETURN_NOT_OK(file->Write(&padded_flatbuffer_size, sizeof(int32_t)));

  // Write the flatbuffer
  RETURN_NOT_OK(file->Write(message.data(), flatbuffer_size));
  if (padding > 0) {
    RETURN_NOT_OK(file->Write(kPaddingBytes, padding));
  }

  return Status::OK();
}

// ----------------------------------------------------------------------
// Implement MessageDecoder