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国外自助建站,百度在线,网站页面开发流程,wordpress集中管理codec 包基础设计 package：trpc-go/codec Msg接口的定义: 后续实际的消息msg结构体实现该接口，可以方便地获取一些值（如Context），也可以方便地进行一些值地设置（如设置SerializationType） //…

codec 包基础设计

package：trpc-go/codec

Msg接口的定义: 后续实际的消息msg结构体实现该接口，可以方便地获取一些值（如Context），也可以方便地进行一些值地设置（如设置SerializationType）

// message.go 文件下 // Msg defines core message data for multi protocol, business protocol
// should set this message when packing and unpacking data.
type Msg interface {// Context returns rpc contextContext() context.Context// WithRemoteAddr sets upstream address for server,// or downstream address for client.WithRemoteAddr(addr net.Addr)// WithLocalAddr sets server local address.WithLocalAddr(addr net.Addr)// RemoteAddr returns upstream address for server,// or downstream address for client.RemoteAddr() net.Addr// LocalAddr returns server local address.LocalAddr() net.Addr// WithNamespace sets server namespace.WithNamespace(string)// Namespace returns server namespace.Namespace() string// WithEnvName sets server environment.WithEnvName(string)// SerializationType returns serialization type.SerializationType() int// WithCompressType sets compress type.WithCompressType(int)....

msg 整个rpc的上下文，先看接口体的设计，以及实现上面Msg接口定义的方法

// message_impl.go 文件// msg is the context of rpc.
type msg struct {context             context.ContextframeHead           interface{}requestTimeout      time.DurationserializationType   intcompressType        intstreamID            uint32dyeing              booldyeingKey           stringserverRPCName       stringclientRPCName       stringserverMetaData      MetaDataclientMetaData      MetaDatacallerServiceName   stringcalleeServiceName   stringcalleeContainerName stringserverRspErr        errorclientRspErr        errorserverReqHead       interface{}serverRspHead       interface{}clientReqHead       interface{}clientRspHead       interface{}localAddr           net.AddrremoteAddr          net.Addrlogger              interface{}callerApp           stringcallerServer        stringcallerService       stringcallerMethod        stringcalleeApp           stringcalleeServer        stringcalleeService       stringcalleeMethod        stringnamespace           stringsetName             stringenvName             stringenvTransfer         stringrequestID           uint32calleeSetName       stringstreamFrame         interface{}commonMeta          CommonMetacallType            RequestType
}// 实现了 Msg接口所有方法
// Context restores old context when create new msg.
func (m *msg) Context() context.Context {return m.context
}// WithNamespace set server's namespace.
func (m *msg) WithNamespace(namespace string) {m.namespace = namespace
}
....

msg在后续：会被写入trpc协议的帧头中，进行网络传输，以达到下游
在这里插入图片描述

客户端调用使用message：GreeterClientProxyImpl

客户端调用具体rpc方法桩代码：

func (c *GreeterClientProxyImpl) Hello(ctx context.Context, req *HelloRequest, opts ...client.Option) (*HelloReply, error) {// 派生出新的消息，以实现整个调用链路的context消息传递ctx, msg := codec.WithCloneMessage(ctx)defer codec.PutBackMessage(msg)msg.WithClientRPCName("/trpc.helloworld.Greeter/Hello")msg.WithCalleeServiceName(GreeterServer_ServiceDesc.ServiceName)msg.WithCalleeApp("")msg.WithCalleeServer("")msg.WithCalleeService("Greeter")msg.WithCalleeMethod("Hello")msg.WithSerializationType(codec.SerializationTypePB)callopts := make([]client.Option, 0, len(c.opts)+len(opts))callopts = append(callopts, c.opts...)callopts = append(callopts, opts...)rsp := &HelloReply{}if err := c.client.Invoke(ctx, req, rsp, callopts...); err != nil {return nil, err}return rsp, nil
}

先看WithCloneMessage方法：主要实现一组新的 ctx 和 msg 的派生

首先可以看到第二个返回值Msg就是之前的接口类型
val.(*msg)是因为context中存储的不是实际结构体，而是结构体的指针
所以上面桩代码中：msg.WithClientRPCName(“/trpc.helloworld.Greeter/Hello”)，WithClientRPCName这些方法都是指针类型的实现：func (m *msg) xxx(namespace string) {

// message_impl.go 文件// WithCloneMessage copy a new message and put into context, each rpc call should
// create a new message, this method will be called by client stub.
func WithCloneMessage(ctx context.Context) (context.Context, Msg) {newMsg := msgPool.Get().(*msg)val := ctx.Value(ContextKeyMessage)m, ok := val.(*msg)if !ok {ctx = context.WithValue(ctx, ContextKeyMessage, newMsg)newMsg.context = ctxreturn ctx, newMsg}ctx = context.WithValue(ctx, ContextKeyMessage, newMsg)newMsg.context = ctxcopyCommonMessage(m, newMsg)copyServerToClientMessage(m, newMsg)return ctx, newMsg
}