聊聊kingbus的respgo

序

本文主要研究一下 kingbus 的 resp.go

writeOK

kingbus/mysql/resp.go

func (c *Conn) writeOK(r *gomysql.Result) error {
    if r == nil {r = &gomysql.Result{}
    }

    r.Status |= c.status

    data := make([]byte, 4, 32)

    data = append(data, gomysql.OK_HEADER)

    data = append(data, gomysql.PutLengthEncodedInt(r.AffectedRows)...)
    data = append(data, gomysql.PutLengthEncodedInt(r.InsertId)...)

    if c.capability&gomysql.CLIENT_PROTOCOL_41 > 0 {data = append(data, byte(r.Status), byte(r.Status>>8))
        data = append(data, 0, 0)
    }

    return c.WritePacket(data)
}

• writeOK 方法写入 gomysql.OK_HEADER

writeError

kingbus/mysql/resp.go

func (c *Conn) writeError(e error) error {
    var m *gomysql.MyError
    var ok bool
    if m, ok = e.(*gomysql.MyError); !ok {m = gomysql.NewError(gomysql.ER_UNKNOWN_ERROR, e.Error())
    }

    data := make([]byte, 4, 16+len(m.Message))

    data = append(data, gomysql.ERR_HEADER)
    data = append(data, byte(m.Code), byte(m.Code>>8))

    if c.capability&gomysql.CLIENT_PROTOCOL_41 > 0 {data = append(data, '#')
        data = append(data, m.State...)
    }

    data = append(data, m.Message...)

    return c.WritePacket(data)
}

• writeError 方法写入 gomysql.ERR_HEADER

writeEOF

kingbus/mysql/resp.go

func (c *Conn) writeEOF() error {data := make([]byte, 4, 9)

    data = append(data, gomysql.EOF_HEADER)
    if c.capability&gomysql.CLIENT_PROTOCOL_41 > 0 {data = append(data, 0, 0)
        data = append(data, byte(c.status), byte(c.status>>8))
    }

    return c.WritePacket(data)
}

• writeEOF 方法写入 gomysql.EOF_HEADER

writeResultset

kingbus/mysql/resp.go

func (c *Conn) writeResultset(r *gomysql.Resultset) error {columnLen := gomysql.PutLengthEncodedInt(uint64(len(r.Fields)))

    data := make([]byte, 4, 1024)

    data = append(data, columnLen...)
    if err := c.WritePacket(data); err != nil {return err}

    for _, v := range r.Fields {data = data[0:4]
        data = append(data, v.Dump()...)
        if err := c.WritePacket(data); err != nil {return err}
    }

    if err := c.writeEOF(); err != nil {return err}

    for _, v := range r.RowDatas {data = data[0:4]
        data = append(data, v...)
        if err := c.WritePacket(data); err != nil {return err}
    }

    if err := c.writeEOF(); err != nil {return err}

    return nil
}

• writeResultset 方法写入 columnLen、data、eof

writeFieldList

kingbus/mysql/resp.go

func (c *Conn) writeFieldList(fs []*gomysql.Field) error {data := make([]byte, 4, 1024)

    for _, v := range fs {data = data[0:4]
        data = append(data, v.Dump()...)
        if err := c.WritePacket(data); err != nil {return err}
    }

    if err := c.writeEOF(); err != nil {return err}
    return nil
}

• writeFieldList 方法写入 data、eof

writeValue

kingbus/mysql/resp.go

func (c *Conn) writeValue(value interface{}) error {switch v := value.(type) {
    case noResponse:
        return nil
    case error:
        return c.writeError(v)
    case nil:
        return c.writeOK(nil)
    case *gomysql.Result:
        if v != nil && v.Resultset != nil {return c.writeResultset(v.Resultset)
        }
        return c.writeOK(v)
    case []*gomysql.Field:
        return c.writeFieldList(v)
    default:
        return fmt.Errorf("invalid response type %T", value)
    }
}

• writeValue 方法根据 value 的 type 来执行不同的写入方法

小结

kingbus 的 resp.go 提供了 writeOK、writeError、writeEOF、writeResultset、writeFieldList、writeValue 方法

doc

• resp