network/frame/meta_frame.go

package frame

import (
	"strconv"
	"time"

	coder "git.hpds.cc/Component/mq_coder"
	gonanoid "github.com/matoous/go-nanoid/v2"
)

// MetaFrame is a coder encoded bytes, SeqId is a fixed value of TYPE_ID_TRANSACTION.
// used for describes metadata for a DataFrame.
type MetaFrame struct {
	tid      string
	metadata []byte
	sourceId string
}

// NewMetaFrame creates a new MetaFrame instance.
func NewMetaFrame() *MetaFrame {
	tid, err := gonanoid.New()
	if err != nil {
		tid = strconv.FormatInt(time.Now().UnixMicro(), 10)
	}
	return &MetaFrame{tid: tid}
}

// SetTransactionId set the transaction id.
func (m *MetaFrame) SetTransactionId(transactionId string) {
	m.tid = transactionId
}

// TransactionId returns transactionId
func (m *MetaFrame) TransactionId() string {
	return m.tid
}

// SetMetadata set the extra info of the application
func (m *MetaFrame) SetMetadata(metadata []byte) {
	m.metadata = metadata
}

// Metadata returns the extra info of the application
func (m *MetaFrame) Metadata() []byte {
	return m.metadata
}

// SetSourceId set the source ID.
func (m *MetaFrame) SetSourceId(sourceId string) {
	m.sourceId = sourceId
}

// SourceId returns source ID
func (m *MetaFrame) SourceId() string {
	return m.sourceId
}

// Encode implements Frame.Encode method.
func (m *MetaFrame) Encode() []byte {
	meta := coder.NewNodePacketEncoder(TagOfMetaFrame)
	// transaction ID
	transactionId := coder.NewPrimitivePacketEncoder(TagOfTransactionId)
	transactionId.SetStringValue(m.tid)
	meta.AddPrimitivePacket(transactionId)

	// source ID
	sourceId := coder.NewPrimitivePacketEncoder(TagOfSourceId)
	sourceId.SetStringValue(m.sourceId)
	meta.AddPrimitivePacket(sourceId)

	// metadata
	if m.metadata != nil {
		metadata := coder.NewPrimitivePacketEncoder(TagOfMetadata)
		metadata.SetBytesValue(m.metadata)
		meta.AddPrimitivePacket(metadata)
	}

	return meta.Encode()
}

// DecodeToMetaFrame decode a MetaFrame instance from given buffer.
func DecodeToMetaFrame(buf []byte) (*MetaFrame, error) {
	nodeBlock := coder.NodePacket{}
	_, err := coder.DecodeToNodePacket(buf, &nodeBlock)
	if err != nil {
		return nil, err
	}

	meta := &MetaFrame{}
	for k, v := range nodeBlock.PrimitivePackets {
		switch k {
		case TagOfTransactionId:
			val, err := v.ToUTF8String()
			if err != nil {
				return nil, err
			}
			meta.tid = val
			break
		case TagOfMetadata:
			meta.metadata = v.ToBytes()
			break
		case TagOfSourceId:
			sourceId, err := v.ToUTF8String()
			if err != nil {
				return nil, err
			}
			meta.sourceId = sourceId
			break
		}
	}

	return meta, nil
}