mirror of
https://github.com/chai2010/advanced-go-programming-book.git
synced 2025-05-24 12:32:21 +00:00
ch4-02: 基于模板简化插件
This commit is contained in:
chai2010
parent
7cbe19c04b
commit
f577312bf2
@ -64,13 +64,13 @@ func (m *String) GetValue() string {
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```go
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type HelloService struct{}
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func (p *HelloService) Hello(request String, reply *String) error {
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func (p *HelloService) Hello(request *String, reply *String) error {
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reply.Value = "hello:" + request.GetValue()
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return nil
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}
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```
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其中Hello方法的输入参数和返回的参数均该用Protobuf定义的String类型表示，函数的内部代码同时也做了相应的调整。
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其中Hello方法的输入参数和返回的参数均该用Protobuf定义的String类型表示。因为新的输入参数为结构体类型，因此该用指针类型作为输入参数，函数的内部代码同时也做了相应的调整。
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至此，我们初步实现了Protobuf和RPC组合工作。在启动RPC服务时，我们依然可以选择默认的gob或手工指定json编码，甚至可以重新基于protobuf编码实现一个插件。虽然做了这么多工作，但是似乎并没有看到什么收益！
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@ -237,7 +237,7 @@ $ protoc --go-netrpc_out=plugins=netrpc:. hello.proto
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在前面的例子中我们已经构件了最小化的netrpcPlugin插件，并且通过克隆protoc-gen-go的主程序创建了新的protoc-gen-go-netrpc的插件程序。我们现在开始继续完善netrpcPlugin插件，最终目标是生成RPC安全接口。
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以下是完善后的GenerateImports和Generate方法：
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首先是GenerateImports方法中生成导入包的代码：
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```go
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func (p *netrpcPlugin) GenerateImports(file *generator.FileDescriptor) {
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@ -245,153 +245,65 @@ func (p *netrpcPlugin) GenerateImports(file *generator.FileDescriptor) {
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p.P(`import "net/rpc"`)
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}
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}
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```
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然后要在Generate中为每个服务生成相关的代码。分析可以发现每个服务最重要的是服务的名字，然后每个服务有一组方法。而对于服务定义的方法，最重要的是方法的名字，还有输入参数和输出参数类型的名字。为此我们定义了一个ServiceSpec类型，用于描述服务的元信息：
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```go
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type ServiceSpec struct {
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ServiceName string
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MethodList []ServiceMethodSpec
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}
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type ServiceMethodSpec struct {
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MethodName string
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InputTypeName string
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OutputTypeName string
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}
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```
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然后我们新建一个buildServiceSpec方法用来构造每个服务的ServiceSpec元信息：
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```go
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func (p *generator.Generator) buildServiceSpec(svc *descriptor.ServiceDescriptorProto) *ServiceSpec {
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spec := &ServiceSpec{
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ServiceName: generator.CamelCase(svc.GetName()),
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}
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for _, m := range svc.Method {
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spec.MethodList = append(spec.MethodList, ServiceMethodSpec{
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MethodName: generator.CamelCase(m.GetName()),
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InputTypeName: p.TypeName(p.ObjectNamed(m.GetInputType())),
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OutputTypeName: p.TypeName(p.ObjectNamed(m.GetOutputType())),
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})
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}
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return spec
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}
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```
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然后我们就可以基于buildServiceSpec方法构造的服务的元信息生成服务的代码：
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```go
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func (p *netrpcPlugin) Generate(file *generator.FileDescriptor) {
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for _, svc := range file.Service {
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p.genServiceInterface(file, svc)
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p.genServiceServer(file, svc)
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p.genServiceClient(file, svc)
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}
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}
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```
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spec := p.buildServiceSpec(svc)
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在导入部分我们增加了导入net/rpc包的语句。而在每个服务部分则通过genServiceInterface方法生成服务的接口，通过genServiceServer方法生成服务的注册函数，通过genServiceClient方法生成客户端包装代码。
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首先看看genServiceInterface如何生成服务器接口：
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```go
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func (p *netrpcPlugin) genServiceInterface(
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file *generator.FileDescriptor,
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svc *descriptor.ServiceDescriptorProto,
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) {
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const serviceInterfaceTmpl = `
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type {{.ServiceName}}Interface interface {
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{{.CallMethodList}}
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}
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`
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const callMethodTmpl = `
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{{.MethodName}}(in {{.ArgsType}}, out *{{.ReplyType}}) error`
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// gen call method list
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var callMethodList string
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for _, m := range svc.Method {
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out := bytes.NewBuffer([]byte{})
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t := template.Must(template.New("").Parse(callMethodTmpl))
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t.Execute(out, &struct{ ServiceName, MethodName, ArgsType, ReplyType string }{
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ServiceName: generator.CamelCase(svc.GetName()),
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MethodName: generator.CamelCase(m.GetName()),
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ArgsType: p.TypeName(p.ObjectNamed(m.GetInputType())),
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ReplyType: p.TypeName(p.ObjectNamed(m.GetOutputType())),
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})
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callMethodList += out.String()
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p.RecordTypeUse(m.GetInputType())
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p.RecordTypeUse(m.GetOutputType())
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}
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// gen all interface code
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out := bytes.NewBuffer([]byte{})
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t := template.Must(template.New("").Parse(serviceInterfaceTmpl))
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t.Execute(out, &struct{ ServiceName, CallMethodList string }{
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ServiceName: generator.CamelCase(svc.GetName()),
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CallMethodList: callMethodList,
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})
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p.P(out.String())
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}
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```
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生成服务接口时首先需要服务的名字，可以通过`svc.GetName()`获取服务在Proto文件中的名字，然后通过generator.CamelCase函数转为Go语言中修饰后的名字。
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服务中svc.Method是一个表示方法信息的切片。要生成每个方法，需要知道每个方法的名字、输入参数类型、输出参数类型。其中m.GetName()是获取原始的方法名字，同样需要通过generator.CamelCase转化为Go语言中修饰后的名字。而`p.TypeName(p.ObjectNamed(m.GetInputType()))`和`p.TypeName(p.ObjectNamed(m.GetOutputType()))`分别用户获取输入参数和输出参数的类型名字。
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然后是生成RPC注册方法的genServiceServer函数：
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```go
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func (p *netrpcPlugin) genServiceServer(
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file *generator.FileDescriptor,
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svc *descriptor.ServiceDescriptorProto,
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) {
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const serviceHelperFunTmpl = `
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func Register{{.ServiceName}}(srv *rpc.Server, x {{.ServiceName}}) error {
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if err := srv.RegisterName("{{.ServiceName}}", x); err != nil {
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return err
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}
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return nil
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}
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`
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out := bytes.NewBuffer([]byte{})
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t := template.Must(template.New("").Parse(serviceHelperFunTmpl))
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t.Execute(out, &struct{ PackageName, ServiceName, ServiceRegisterName string }{
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PackageName: file.GetPackage(),
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ServiceName: generator.CamelCase(svc.GetName()),
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})
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p.P(out.String())
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}
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```
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genServiceServer函数的实现和生成接口的代码类似，依然是才有Go语言的模板生成目标代码。
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最后是genServiceClient函数生成客户端包装代码：
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```go
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func (p *netrpcPlugin) genServiceClient(
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file *generator.FileDescriptor,
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svc *descriptor.ServiceDescriptorProto,
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) {
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const clientHelperFuncTmpl = `
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type {{.ServiceName}}Client struct {
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*rpc.Client
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}
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var _ {{.ServiceName}}Interface = (*{{.ServiceName}}Client)(nil)
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func Dial{{.ServiceName}}(network, address string) (*{{.ServiceName}}Client, error) {
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c, err := rpc.Dial(network, address)
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var buf bytes.Buffer
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t := template.Must(template.New("").Parse(tmplService))
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err := t.Execute(&buf, spec)
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if err != nil {
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return nil, err
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}
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return &{{.ServiceName}}Client{Client: c}, nil
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log.Fatal(err)
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}
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{{.MethodList}}
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`
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const clientMethodTmpl = `
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func (p *{{.ServiceName}}Client) {{.MethodName}}(in {{.ArgsType}}, out *{{.ReplyType}}) error {
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return p.Client.Call("{{.ServiceName}}.{{.MethodName}}", in, out)
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p.P(buf.String())
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}
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`
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// gen client method list
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var methodList string
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for _, m := range svc.Method {
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out := bytes.NewBuffer([]byte{})
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t := template.Must(template.New("").Parse(clientMethodTmpl))
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t.Execute(out, &struct{ ServiceName, ServiceRegisterName, MethodName, ArgsType, ReplyType string }{
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ServiceName: generator.CamelCase(svc.GetName()),
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ServiceRegisterName: file.GetPackage() + "." + generator.CamelCase(svc.GetName()),
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MethodName: generator.CamelCase(m.GetName()),
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ArgsType: p.TypeName(p.ObjectNamed(m.GetInputType())),
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ReplyType: p.TypeName(p.ObjectNamed(m.GetOutputType())),
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})
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methodList += out.String()
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}
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// gen all client code
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out := bytes.NewBuffer([]byte{})
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t := template.Must(template.New("").Parse(clientHelperFuncTmpl))
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t.Execute(out, &struct{ PackageName, ServiceName, MethodList string }{
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PackageName: file.GetPackage(),
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ServiceName: generator.CamelCase(svc.GetName()),
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MethodList: methodList,
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})
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p.P(out.String())
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}
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```
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除了模板不同，客户端的生成代码逻辑服务接口的生成函数也是类似的。
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为了便于维护，我们基于Go语言的模板来生成服务代码，其中tmplService是服务的模板。
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最后我们可以查看下netrpcPlugin插件生成的RPC代码：
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在编写模板之前，我们先查看下我们期望生成的最终代码大概是什么样子：
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```go
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type HelloServiceInterface interface {
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@ -424,6 +336,49 @@ func (p *HelloServiceClient) Hello(in String, out *String) error {
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}
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```
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其中HelloService是服务名字，同时还有一系列的方法相关的名字。
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参考最终要生成的代码可以构建如下模板：
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```go
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const tmplService = `
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{{$root := .}}
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type {{.ServiceName}}Interface interface {
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{{- range $_, $m := .MethodList}}
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{{$m.MethodName}}(in *{{$m.InputTypeName}}, out *{{$m.OutputTypeName}}) error
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{{- end}}
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}
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func Register{{.ServiceName}}(srv *rpc.Server, x {{.ServiceName}}) error {
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if err := srv.RegisterName("{{.ServiceName}}", x); err != nil {
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return err
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}
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return nil
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}
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type {{.ServiceName}}Client struct {
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*rpc.Client
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}
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var _ {{.ServiceName}}Interface = (*{{.ServiceName}}Client)(nil)
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func Dial{{.ServiceName}}(network, address string) (*{{.ServiceName}}Client, error) {
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c, err := rpc.Dial(network, address)
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if err != nil {
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return nil, err
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}
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return &{{.ServiceName}}Client{Client: c}, nil
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}
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{{range $_, $m := .MethodList}}
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func (p *{{$root.ServiceName}}Client) {{$m.MethodName}}(in *{{$m.InputTypeName}}, out *{{$m.OutputTypeName}}) error {
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return p.Client.Call("{{$root.ServiceName}}.{{$m.MethodName}}", in, out)
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}
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{{end}}
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`
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```
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当Protobuf的插件定制工作完成后，每次hello.proto文件中RPC服务的变化都可以自动生成代码。同时，才有类似的技术也可以为其它语言编写代码生成插件。
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在掌握了定制Protobuf插件技术后，你将彻底拥有这个技术。
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@ -63,7 +63,7 @@ func init() {
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}
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type HelloServiceInterface interface {
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Hello(in String, out *String) error
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Hello(in *String, out *String) error
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}
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func RegisterHelloService(srv *rpc.Server, x HelloService) error {
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@ -87,7 +87,7 @@ func DialHelloService(network, address string) (*HelloServiceClient, error) {
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return &HelloServiceClient{Client: c}, nil
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}
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func (p *HelloServiceClient) Hello(in String, out *String) error {
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func (p *HelloServiceClient) Hello(in *String, out *String) error {
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return p.Client.Call("HelloService.Hello", in, out)
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}
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@ -1,4 +1,4 @@
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// Copyright 2013 <chaishushan{AT}gmail.com>. All rights reserved.
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// Copyright 2018 <chaishushan{AT}gmail.com>. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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@ -6,12 +6,16 @@ package main
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import (
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"bytes"
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"log"
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"text/template"
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"github.com/golang/protobuf/protoc-gen-go/descriptor"
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"github.com/golang/protobuf/protoc-gen-go/generator"
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)
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func init() {
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generator.RegisterPlugin(new(netrpcPlugin))
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}
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type netrpcPlugin struct{ *generator.Generator }
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func (p *netrpcPlugin) Name() string { return "netrpc" }
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@ -25,81 +29,35 @@ func (p *netrpcPlugin) GenerateImports(file *generator.FileDescriptor) {
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func (p *netrpcPlugin) Generate(file *generator.FileDescriptor) {
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for _, svc := range file.Service {
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p.genServiceInterface(file, svc)
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p.genServiceServer(file, svc)
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p.genServiceClient(file, svc)
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spec := p.buildServiceSpec(svc)
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var buf bytes.Buffer
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t := template.Must(template.New("").Parse(tmplService))
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err := t.Execute(&buf, spec)
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if err != nil {
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log.Fatal(err)
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}
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p.P(buf.String())
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}
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}
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func (p *netrpcPlugin) genServiceInterface(
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file *generator.FileDescriptor,
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svc *descriptor.ServiceDescriptorProto,
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) {
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const serviceInterfaceTmpl = `
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const tmplService = `
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{{$root := .}}
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type {{.ServiceName}}Interface interface {
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{{.CallMethodList}}
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}
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`
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const callMethodTmpl = `
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{{.MethodName}}(in {{.ArgsType}}, out *{{.ReplyType}}) error`
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// gen call method list
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var callMethodList string
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for _, m := range svc.Method {
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out := bytes.NewBuffer([]byte{})
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t := template.Must(template.New("").Parse(callMethodTmpl))
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t.Execute(out, &struct{ ServiceName, MethodName, ArgsType, ReplyType string }{
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ServiceName: generator.CamelCase(svc.GetName()),
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MethodName: generator.CamelCase(m.GetName()),
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ArgsType: p.TypeName(p.ObjectNamed(m.GetInputType())),
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ReplyType: p.TypeName(p.ObjectNamed(m.GetOutputType())),
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})
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callMethodList += out.String()
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p.RecordTypeUse(m.GetInputType())
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p.RecordTypeUse(m.GetOutputType())
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{{- range $_, $m := .MethodList}}
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{{$m.MethodName}}(in *{{$m.InputTypeName}}, out *{{$m.OutputTypeName}}) error
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{{- end}}
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}
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// gen all interface code
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{
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out := bytes.NewBuffer([]byte{})
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t := template.Must(template.New("").Parse(serviceInterfaceTmpl))
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t.Execute(out, &struct{ ServiceName, CallMethodList string }{
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ServiceName: generator.CamelCase(svc.GetName()),
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CallMethodList: callMethodList,
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})
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p.P(out.String())
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}
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}
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func (p *netrpcPlugin) genServiceServer(
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file *generator.FileDescriptor,
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svc *descriptor.ServiceDescriptorProto,
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) {
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const serviceHelperFunTmpl = `
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func Register{{.ServiceName}}(srv *rpc.Server, x {{.ServiceName}}) error {
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if err := srv.RegisterName("{{.ServiceName}}", x); err != nil {
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return err
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}
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return nil
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}
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`
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{
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out := bytes.NewBuffer([]byte{})
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t := template.Must(template.New("").Parse(serviceHelperFunTmpl))
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t.Execute(out, &struct{ PackageName, ServiceName, ServiceRegisterName string }{
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PackageName: file.GetPackage(),
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ServiceName: generator.CamelCase(svc.GetName()),
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})
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p.P(out.String())
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}
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}
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func (p *netrpcPlugin) genServiceClient(
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file *generator.FileDescriptor,
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svc *descriptor.ServiceDescriptorProto,
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) {
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const clientHelperFuncTmpl = `
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type {{.ServiceName}}Client struct {
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*rpc.Client
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}
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@ -114,42 +72,9 @@ func Dial{{.ServiceName}}(network, address string) (*{{.ServiceName}}Client, err
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return &{{.ServiceName}}Client{Client: c}, nil
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}
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{{.MethodList}}
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{{range $_, $m := .MethodList}}
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func (p *{{$root.ServiceName}}Client) {{$m.MethodName}}(in *{{$m.InputTypeName}}, out *{{$m.OutputTypeName}}) error {
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return p.Client.Call("{{$root.ServiceName}}.{{$m.MethodName}}", in, out)
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}
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{{end}}
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`
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const clientMethodTmpl = `
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func (p *{{.ServiceName}}Client) {{.MethodName}}(in {{.ArgsType}}, out *{{.ReplyType}}) error {
|
||||
return p.Client.Call("{{.ServiceName}}.{{.MethodName}}", in, out)
|
||||
}
|
||||
`
|
||||
|
||||
// gen client method list
|
||||
var methodList string
|
||||
for _, m := range svc.Method {
|
||||
out := bytes.NewBuffer([]byte{})
|
||||
t := template.Must(template.New("").Parse(clientMethodTmpl))
|
||||
t.Execute(out, &struct{ ServiceName, ServiceRegisterName, MethodName, ArgsType, ReplyType string }{
|
||||
ServiceName: generator.CamelCase(svc.GetName()),
|
||||
ServiceRegisterName: file.GetPackage() + "." + generator.CamelCase(svc.GetName()),
|
||||
MethodName: generator.CamelCase(m.GetName()),
|
||||
ArgsType: p.TypeName(p.ObjectNamed(m.GetInputType())),
|
||||
ReplyType: p.TypeName(p.ObjectNamed(m.GetOutputType())),
|
||||
})
|
||||
methodList += out.String()
|
||||
}
|
||||
|
||||
// gen all client code
|
||||
{
|
||||
out := bytes.NewBuffer([]byte{})
|
||||
t := template.Must(template.New("").Parse(clientHelperFuncTmpl))
|
||||
t.Execute(out, &struct{ PackageName, ServiceName, MethodList string }{
|
||||
PackageName: file.GetPackage(),
|
||||
ServiceName: generator.CamelCase(svc.GetName()),
|
||||
MethodList: methodList,
|
||||
})
|
||||
p.P(out.String())
|
||||
}
|
||||
}
|
||||
|
||||
func init() {
|
||||
generator.RegisterPlugin(new(netrpcPlugin))
|
||||
}
|
||||
|
||||
37
examples/ch4-02-proto/protoc-gen-go-netrpc/spec.go
Normal file
37
examples/ch4-02-proto/protoc-gen-go-netrpc/spec.go
Normal file
@ -0,0 +1,37 @@
|
||||
// Copyright 2018 <chaishushan{AT}gmail.com>. All rights reserved.
|
||||
// Use of this source code is governed by a BSD-style
|
||||
// license that can be found in the LICENSE file.
|
||||
|
||||
package main
|
||||
|
||||
import (
|
||||
"github.com/golang/protobuf/protoc-gen-go/descriptor"
|
||||
"github.com/golang/protobuf/protoc-gen-go/generator"
|
||||
)
|
||||
|
||||
type ServiceSpec struct {
|
||||
ServiceName string
|
||||
MethodList []ServiceMethodSpec
|
||||
}
|
||||
|
||||
type ServiceMethodSpec struct {
|
||||
MethodName string
|
||||
InputTypeName string
|
||||
OutputTypeName string
|
||||
}
|
||||
|
||||
func (p *netrpcPlugin) buildServiceSpec(svc *descriptor.ServiceDescriptorProto) *ServiceSpec {
|
||||
spec := &ServiceSpec{
|
||||
ServiceName: generator.CamelCase(svc.GetName()),
|
||||
}
|
||||
|
||||
for _, m := range svc.Method {
|
||||
spec.MethodList = append(spec.MethodList, ServiceMethodSpec{
|
||||
MethodName: generator.CamelCase(m.GetName()),
|
||||
InputTypeName: p.TypeName(p.ObjectNamed(m.GetInputType())),
|
||||
OutputTypeName: p.TypeName(p.ObjectNamed(m.GetOutputType())),
|
||||
})
|
||||
}
|
||||
|
||||
return spec
|
||||
}
|
||||
Loading…
x
Reference in New Issue
Block a user