func packRequest()

in request.go [183:268]
61 lines of code
11 McCabe index (conditional complexity)

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

	request := EnsureRequest(req)

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

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

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

	// dubbo version + path + version + method
	encoder.Encode(DEFAULT_DUBBO_PROTOCOL_VERSION)
	encoder.Encode(service.Path)
	encoder.Encode(service.Version)
	encoder.Encode(service.Method)

	// 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) { // 8M
		return nil, perrors.Errorf("Data length %d too large, max payload %d", pkgLen, DEFAULT_LEN)
	}
	// byteArray{body length}
	binary.BigEndian.PutUint32(byteArray[12:], uint32(pkgLen-HEADER_LENGTH))
	return byteArray, nil
}