聊聊dubbo-go的DubboPackage

序

本文只要研究一下dubbo-go的DubboPackage

DubboPackage

dubbo-go-v1.4.2/protocol/dubbo/codec.go

//CallType call type
type CallType int32

const (
    // CT_UNKNOWN unknown call type
    CT_UNKNOWN CallType = 0
    // CT_OneWay call one way
    CT_OneWay CallType = 1
    // CT_TwoWay call in request/response
    CT_TwoWay CallType = 2
)

// SequenceType ...
type SequenceType int64

// DubboPackage ...
type DubboPackage struct {
    Header  hessian.DubboHeader
    Service hessian.Service
    Body    interface{}
    Err     error
}

• DubboPackage定义了Header、Service、Body、Err属性

Marshal

dubbo-go-v1.4.2/protocol/dubbo/codec.go

// Marshal ...
func (p *DubboPackage) Marshal() (*bytes.Buffer, error) {
    codec := hessian.NewHessianCodec(nil)

    pkg, err := codec.Write(p.Service, p.Header, p.Body)
    if err != nil {
        return nil, perrors.WithStack(err)
    }

    return bytes.NewBuffer(pkg), nil
}

• Marshal方法通过hessian.NewHessianCodec(nil)创建codec，之后执行bytes.NewBuffer(pkg)

Unmarshal

dubbo-go-v1.4.2/protocol/dubbo/codec.go

// Unmarshal ...
func (p *DubboPackage) Unmarshal(buf *bytes.Buffer, opts ...interface{}) error {
    // fix issue https://github.com/apache/dubbo-go/issues/380
    bufLen := buf.Len()
    if bufLen < hessian.HEADER_LENGTH {
        return perrors.WithStack(hessian.ErrHeaderNotEnough)
    }

    codec := hessian.NewHessianCodec(bufio.NewReaderSize(buf, bufLen))

    // read header
    err := codec.ReadHeader(&p.Header)
    if err != nil {
        return perrors.WithStack(err)
    }

    if len(opts) != 0 { // for client
        client, ok := opts[0].(*Client)
        if !ok {
            return perrors.Errorf("opts[0] is not of type *Client")
        }

        if p.Header.Type&hessian.PackageRequest != 0x00 {
            // size of this array must be '7'
            // https://github.com/apache/dubbo-go-hessian2/blob/master/request.go#L272
            p.Body = make([]interface{}, 7)
        } else {
            pendingRsp, ok := client.pendingResponses.Load(SequenceType(p.Header.ID))
            if !ok {
                return perrors.Errorf("client.GetPendingResponse(%v) = nil", p.Header.ID)
            }
            p.Body = &hessian.Response{RspObj: pendingRsp.(*PendingResponse).response.reply}
        }
    }

    // read body
    err = codec.ReadBody(p.Body)
    return perrors.WithStack(err)
}

• Unmarshal方法先通过hessian.NewHessianCodec(bufio.NewReaderSize(buf, bufLen))创建codec，然后执行codec.ReadHeader(&p.Header)读取header，最后通过codec.ReadBody(p.Body)读取body

PendingResponse

dubbo-go-v1.4.2/protocol/dubbo/codec.go

// PendingResponse ...
type PendingResponse struct {
    seq       uint64
    err       error
    start     time.Time
    readStart time.Time
    callback  common.AsyncCallback
    response  *Response
    done      chan struct{}
}

// NewPendingResponse ...
func NewPendingResponse() *PendingResponse {
    return &PendingResponse{
        start:    time.Now(),
        response: &Response{},
        done:     make(chan struct{}),
    }
}

• NewPendingResponse实例化了PendingResponse

GetCallResponse

dubbo-go-v1.4.2/protocol/dubbo/codec.go

// GetCallResponse ...
func (r PendingResponse) GetCallResponse() common.CallbackResponse {
    return AsyncCallbackResponse{
        Cause:     r.err,
        Start:     r.start,
        ReadStart: r.readStart,
        Reply:     r.response,
    }
}

• GetCallResponse方法实例化AsyncCallbackResponse

小结

DubboPackage定义了Header、Service、Body、Err属性；codec.go提供了Marshal、Unmarshal方法用于读写DubboPackage

doc

• codec