func packRequest()

in protocol/dubbo/hessian2/hessian_request.go [86:180]
70 lines of code
15 McCabe index (conditional complexity)

func packRequest(service Service, header DubboHeader, req any) ([]byte, error) {
	var (
		err       error
		types     string
		byteArray []byte
		pkgLen    int
	)

	request := EnsureRequest(req)

	args, ok := request.Params.([]any)
	if !ok {
		return nil, perrors.Errorf("@params is not of type: []any")
	}

	hb := header.Type == PackageHeartbeat

	//////////////////////////////////////////
	// byteArray
	//////////////////////////////////////////
	// magic
	switch header.Type {
	case PackageHeartbeat:
		byteArray = append(byteArray, DubboRequestHeartbeatHeader[:]...)
	case PackageRequest_TwoWay:
		byteArray = append(byteArray, DubboRequestHeaderBytesTwoWay[:]...)
	default:
		byteArray = append(byteArray, DubboRequestHeaderBytes[:]...)
	}

	// serialization id, two way flag, event, request/response flag
	// SerialID is id of serialization approach in java dubbo
	byteArray[2] |= header.SerialID & SERIAL_MASK
	// request id
	binary.BigEndian.PutUint64(byteArray[4:], uint64(header.ID))

	encoder := hessian.NewEncoder()
	encoder.Append(byteArray[:HEADER_LENGTH])

	//////////////////////////////////////////
	// body
	//////////////////////////////////////////
	if hb {
		_ = encoder.Encode(nil)
		goto END
	}

	// dubbo version + path + version + method
	if err = encoder.Encode(DEFAULT_DUBBO_PROTOCOL_VERSION); err != nil {
		logger.Warnf("Encode(DEFAULT_DUBBO_PROTOCOL_VERSION) = error: %v", err)
	}
	if err = encoder.Encode(service.Path); err != nil {
		logger.Warnf("Encode(service.Path) = error: %v", err)
	}
	if err = encoder.Encode(service.Version); err != nil {
		logger.Warnf("Encode(service.Version) = error: %v", err)
	}
	if err = encoder.Encode(service.Method); err != nil {
		logger.Warnf("Encode(service.Method) = error: %v", err)
	}

	// args = args type list + args value list
	if types, err = getArgsTypeList(args); err != nil {
		return nil, perrors.Wrapf(err, " PackRequest(args:%+v)", args)
	}
	_ = encoder.Encode(types)
	for _, v := range args {
		_ = encoder.Encode(v)
	}

	request.Attachments[PATH_KEY] = service.Path
	request.Attachments[VERSION_KEY] = service.Version
	if len(service.Group) > 0 {
		request.Attachments[GROUP_KEY] = service.Group
	}
	if len(service.Interface) > 0 {
		request.Attachments[INTERFACE_KEY] = service.Interface
	}
	if service.Timeout != 0 {
		request.Attachments[TIMEOUT_KEY] = strconv.Itoa(int(service.Timeout / time.Millisecond))
	}

	_ = encoder.Encode(request.Attachments)

END:
	byteArray = encoder.Buffer()
	pkgLen = len(byteArray)
	if pkgLen > int(DEFAULT_LEN) { // recommand 8M
		logger.Warnf("Data length %d too large, recommand max payload %d. "+
			"Dubbo java can't handle the package whose size is greater than %d!!!", pkgLen, DEFAULT_LEN, DEFAULT_LEN)
	}
	// byteArray{body length}
	binary.BigEndian.PutUint32(byteArray[12:], uint32(pkgLen-HEADER_LENGTH))
	return byteArray, nil
}