聊聊canal-go的SimpleCanalConnector

序

本文主要研究一下canal-go的SimpleCanalConnector

SimpleCanalConnector

canal-go-v1.0.7/client/simple_canal_connector.go

type SimpleCanalConnector struct {
    Address           string
    Port              int
    UserName          string
    PassWord          string
    SoTime            int32
    IdleTimeOut       int32
    ClientIdentity    pb.ClientIdentity
    Connected         bool
    Running           bool
    Filter            string
    RollbackOnConnect bool
    LazyParseEntry    bool
}

• SimpleCanalConnector定义了Address、Port、UserName、PassWord、SoTime、IdleTimeOut、ClientIdentity、Connected、Running、Filter、RollbackOnConnect、LazyParseEntry属性

NewSimpleCanalConnector

canal-go-v1.0.7/client/simple_canal_connector.go

//NewSimpleCanalConnector 创建SimpleCanalConnector实例
func NewSimpleCanalConnector(address string, port int, username string, password string, destination string, soTimeOut int32, idleTimeOut int32) *SimpleCanalConnector {
    s := &SimpleCanalConnector{
        Address:           address,
        Port:              port,
        UserName:          username,
        PassWord:          password,
        ClientIdentity:    pb.ClientIdentity{Destination: destination, ClientId: 1001},
        SoTime:            soTimeOut,
        IdleTimeOut:       idleTimeOut,
        RollbackOnConnect: true,
    }
    return s

}

• NewSimpleCanalConnector方法创建了SimpleCanalConnector实例

Connect

canal-go-v1.0.7/client/simple_canal_connector.go

//Connect 连接Canal-server
func (c *SimpleCanalConnector) Connect() error {
    if c.Connected {
        return nil
    }

    if c.Running {
        return nil
    }

    err := c.doConnect()
    if err != nil {
        return err
    }
    if c.Filter != "" {
        c.Subscribe(c.Filter)
    }

    if c.RollbackOnConnect {
        c.waitClientRunning()

        c.RollBack(0)
    }

    c.Connected = true
    return nil

}

• Connect方法主要执行c.doConnect()、c.Subscribe(c.Filter)方法，若RollbackOnConnect为true则再执行c.waitClientRunning()及c.RollBack(0)方法

DisConnection

canal-go-v1.0.7/client/simple_canal_connector.go

//DisConnection 关闭连接
func (c *SimpleCanalConnector) DisConnection() {
    if c.RollbackOnConnect && c.Connected == true {
        c.RollBack(0)
    }
    c.Connected = false
    quitelyClose()
}

//quitelyClose 优雅关闭
func quitelyClose() {
    if conn != nil {
        conn.Close()
    }
}

• DisConnection方法主要是执行conn.Close()

doConnect

canal-go-v1.0.7/client/simple_canal_connector.go

//doConnect 去连接Canal-Server
func (c SimpleCanalConnector) doConnect() error {
    address := c.Address + ":" + fmt.Sprintf("%d", c.Port)
    con, err := net.Dial("tcp", address)
    if err != nil {
        return err
    }
    conn = con

    p := new(pb.Packet)
    data, err := readNextPacket()
    if err != nil {
        return err
    }
    err = proto.Unmarshal(data, p)
    if err != nil {
        return err
    }
    if p != nil {
        if p.GetVersion() != 1 {
            panic("unsupported version at this client.")
        }

        if p.GetType() != pb.PacketType_HANDSHAKE {
            panic("expect handshake but found other type.")
        }

        handshake := &pb.Handshake{}
        err = proto.Unmarshal(p.GetBody(), handshake)
        if err != nil {
            return err
        }
        pas := []byte(c.PassWord)
        ca := &pb.ClientAuth{
            Username:               c.UserName,
            Password:               pas,
            NetReadTimeoutPresent:  &pb.ClientAuth_NetReadTimeout{NetReadTimeout: c.IdleTimeOut},
            NetWriteTimeoutPresent: &pb.ClientAuth_NetWriteTimeout{NetWriteTimeout: c.IdleTimeOut},
        }
        caByteArray, _ := proto.Marshal(ca)
        packet := &pb.Packet{
            Type: pb.PacketType_CLIENTAUTHENTICATION,
            Body: caByteArray,
        }

        packArray, _ := proto.Marshal(packet)

        WriteWithHeader(packArray)

        pp, err := readNextPacket()
        if err != nil {
            return err
        }
        pk := &pb.Packet{}

        err = proto.Unmarshal(pp, pk)
        if err != nil {
            return err
        }

        if pk.Type != pb.PacketType_ACK {
            panic("unexpected packet type when ack is expected")
        }

        ackBody := &pb.Ack{}
        err = proto.Unmarshal(pk.GetBody(), ackBody)
        if err != nil {
            return err
        }
        if ackBody.GetErrorCode() > 0 {

            panic(errors.New(fmt.Sprintf("something goes wrong when doing authentication:%s", ackBody.GetErrorMessage())))
        }

        c.Connected = true

    }
    return nil

}

• doConnect方法通过net.Dial("tcp", address)建立连接，然后通过readNextPacket读取data，然后通过proto.Unmarshal(data, p)来解析，之后发送PacketType_CLIENTAUTHENTICATION数据进行鉴权，若ack成功则设置c.Connected为true

GetWithOutAck

canal-go-v1.0.7/client/simple_canal_connector.go

//GetWithOutAck 获取数据不Ack
func (c *SimpleCanalConnector) GetWithOutAck(batchSize int32, timeOut *int64, units *int32) (*pb.Message, error) {
    c.waitClientRunning()
    if !c.Running {
        return nil, nil
    }
    var size int32

    if batchSize < 0 {
        size = 1000
    } else {
        size = batchSize
    }
    var time *int64
    var t int64
    t = -1
    if timeOut == nil {
        time = &t
    } else {
        time = timeOut
    }
    var i int32
    i = -1
    if units == nil {
        units = &i
    }
    get := new(pb.Get)
    get.AutoAckPresent = &pb.Get_AutoAck{AutoAck: false}
    get.Destination = c.ClientIdentity.Destination
    get.ClientId = strconv.Itoa(c.ClientIdentity.ClientId)
    get.FetchSize = size
    get.TimeoutPresent = &pb.Get_Timeout{Timeout: *time}
    get.UnitPresent = &pb.Get_Unit{Unit: *units}

    getBody, err := proto.Marshal(get)
    if err != nil {
        return nil, err
    }
    packet := new(pb.Packet)
    packet.Type = pb.PacketType_GET
    packet.Body = getBody
    pa, err := proto.Marshal(packet)
    if err != nil {
        return nil, err
    }
    WriteWithHeader(pa)
    message, err := c.receiveMessages()
    if err != nil {
        return nil, err
    }
    return message, nil
}

• GetWithOutAck方法主要是执行WriteWithHeader(pa)以及c.receiveMessages()

Get

canal-go-v1.0.7/client/simple_canal_connector.go

//Get 获取数据并且Ack数据
func (c *SimpleCanalConnector) Get(batchSize int32, timeOut *int64, units *int32) (*pb.Message, error) {
    message, err := c.GetWithOutAck(batchSize, timeOut, units)
    if err != nil {
        return nil, err
    }
    err = c.Ack(message.Id)
    if err != nil {
        return nil, err
    }
    return message, nil
}

• Get方法先执行c.GetWithOutAck(batchSize, timeOut, units)，再执行c.Ack(message.Id)

Ack

canal-go-v1.0.7/client/simple_canal_connector.go

//Ack Ack Canal-server的数据（就是昨晚某些逻辑操作后删除canal-server端的数据）
func (c *SimpleCanalConnector) Ack(batchId int64) error {
    c.waitClientRunning()
    if !c.Running {
        return nil
    }

    ca := new(pb.ClientAck)
    ca.Destination = c.ClientIdentity.Destination
    ca.ClientId = strconv.Itoa(c.ClientIdentity.ClientId)
    ca.BatchId = batchId

    clientAck, err := proto.Marshal(ca)
    if err != nil {
        return err
    }
    pa := new(pb.Packet)
    pa.Type = pb.PacketType_CLIENTACK
    pa.Body = clientAck
    pack, err := proto.Marshal(pa)
    if err != nil {
        return err
    }
    WriteWithHeader(pack)
    return nil

}

• Ack方法主要是发送pb.PacketType_CLIENTACK

Subscribe

canal-go-v1.0.7/client/simple_canal_connector.go

//Subscribe 订阅
func (c *SimpleCanalConnector) Subscribe(filter string) error {
    c.waitClientRunning()
    if !c.Running {
        return nil
    }
    body, _ := proto.Marshal(&pb.Sub{Destination: c.ClientIdentity.Destination, ClientId: strconv.Itoa(c.ClientIdentity.ClientId), Filter: filter})
    pack := new(pb.Packet)
    pack.Type = pb.PacketType_SUBSCRIPTION
    pack.Body = body

    packet, _ := proto.Marshal(pack)
    WriteWithHeader(packet)

    p := new(pb.Packet)

    paBytes, err := readNextPacket()
    if err != nil {
        return err
    }
    err = proto.Unmarshal(paBytes, p)
    if err != nil {
        return err
    }
    ack := new(pb.Ack)
    err = proto.Unmarshal(p.Body, ack)
    if err != nil {
        return err
    }

    if ack.GetErrorCode() > 0 {
        return fmt.Errorf("failed to subscribe with reason::%s", ack.GetErrorMessage())
    }

    c.Filter = filter

    return nil
}

• Subscribe方法主要是发送pb.PacketType_SUBSCRIPTION

UnSubscribe

canal-go-v1.0.7/client/simple_canal_connector.go

//UnSubscribe 取消订阅
func (c *SimpleCanalConnector) UnSubscribe() error {
    c.waitClientRunning()
    if c.Running {
        return nil
    }

    us := new(pb.Unsub)
    us.Destination = c.ClientIdentity.Destination
    us.ClientId = strconv.Itoa(c.ClientIdentity.ClientId)

    unSub, err := proto.Marshal(us)
    if err != nil {
        return err
    }

    pa := new(pb.Packet)
    pa.Type = pb.PacketType_UNSUBSCRIPTION
    pa.Body = unSub

    pack, err := proto.Marshal(pa)
    WriteWithHeader(pack)

    p, err := readNextPacket()
    if err != nil {
        return err
    }
    pa = nil
    err = proto.Unmarshal(p, pa)
    if err != nil {
        return err
    }
    ack := new(pb.Ack)
    err = proto.Unmarshal(pa.Body, ack)
    if err != nil {
        return err
    }
    if ack.GetErrorCode() > 0 {
        panic(errors.New(fmt.Sprintf("failed to unSubscribe with reason:%s", ack.GetErrorMessage())))
    }
    return nil
}

• UnSubscribe方法主要是发送pb.PacketType_UNSUBSCRIPTION

RollBack

canal-go-v1.0.7/client/simple_canal_connector.go

//RollBack 回滚操作
func (c *SimpleCanalConnector) RollBack(batchId int64) error {
    c.waitClientRunning()
    cb := new(pb.ClientRollback)
    cb.Destination = c.ClientIdentity.Destination
    cb.ClientId = strconv.Itoa(c.ClientIdentity.ClientId)
    cb.BatchId = batchId

    clientBollBack, err := proto.Marshal(cb)
    if err != nil {
        return err
    }

    pa := new(pb.Packet)
    pa.Type = pb.PacketType_CLIENTROLLBACK
    pa.Body = clientBollBack
    pack, err := proto.Marshal(pa)
    if err != nil {
        return err
    }
    WriteWithHeader(pack)
    return nil
}

• RollBack方法主要是发送pb.PacketType_CLIENTROLLBACK

小结

SimpleCanalConnector定义了Address、Port、UserName、PassWord、SoTime、IdleTimeOut、ClientIdentity、Connected、Running、Filter、RollbackOnConnect、LazyParseEntry属性；它提供了Connect、DisConnection、GetWithOutAck、Get、Ack、Subscribe、UnSubscribe、RollBack方法

doc

• simple_canal_connector