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@dsnet @dsymonds @neild @iamqizhao @prannayk @menghanl @goller @dfawley @jadekler @paranoiacblack
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// Go support for Protocol Buffers - Google's data interchange format
//
// Copyright 2015 The Go Authors. All rights reserved.
// https://github.com/golang/protobuf
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// Package grpc outputs gRPC service descriptions in Go code.
// It runs as a plugin for the Go protocol buffer compiler plugin.
// It is linked in to protoc-gen-go.
package grpc
import (
"fmt"
"strconv"
"strings"
pb "github.com/golang/protobuf/protoc-gen-go/descriptor"
"github.com/golang/protobuf/protoc-gen-go/generator"
)
// generatedCodeVersion indicates a version of the generated code.
// It is incremented whenever an incompatibility between the generated code and
// the grpc package is introduced; the generated code references
// a constant, grpc.SupportPackageIsVersionN (where N is generatedCodeVersion).
const generatedCodeVersion = 4
// Paths for packages used by code generated in this file,
// relative to the import_prefix of the generator.Generator.
const (
contextPkgPath = "context"
grpcPkgPath = "google.golang.org/grpc"
codePkgPath = "google.golang.org/grpc/codes"
statusPkgPath = "google.golang.org/grpc/status"
)
func init() {
generator.RegisterPlugin(new(grpc))
}
// grpc is an implementation of the Go protocol buffer compiler's
// plugin architecture. It generates bindings for gRPC support.
type grpc struct {
gen *generator.Generator
}
// Name returns the name of this plugin, "grpc".
func (g *grpc) Name() string {
return "grpc"
}
// The names for packages imported in the generated code.
// They may vary from the final path component of the import path
// if the name is used by other packages.
var (
contextPkg string
grpcPkg string
)
// Init initializes the plugin.
func (g *grpc) Init(gen *generator.Generator) {
g.gen = gen
}
// Given a type name defined in a .proto, return its object.
// Also record that we're using it, to guarantee the associated import.
func (g *grpc) objectNamed(name string) generator.Object {
g.gen.RecordTypeUse(name)
return g.gen.ObjectNamed(name)
}
// Given a type name defined in a .proto, return its name as we will print it.
func (g *grpc) typeName(str string) string {
return g.gen.TypeName(g.objectNamed(str))
}
// P forwards to g.gen.P.
func (g *grpc) P(args ...interface{}) { g.gen.P(args...) }
// Generate generates code for the services in the given file.
func (g *grpc) Generate(file *generator.FileDescriptor) {
if len(file.FileDescriptorProto.Service) == 0 {
return
}
contextPkg = string(g.gen.AddImport(contextPkgPath))
grpcPkg = string(g.gen.AddImport(grpcPkgPath))
g.P("// Reference imports to suppress errors if they are not otherwise used.")
g.P("var _ ", contextPkg, ".Context")
g.P("var _ ", grpcPkg, ".ClientConn")
g.P()
// Assert version compatibility.
g.P("// This is a compile-time assertion to ensure that this generated file")
g.P("// is compatible with the grpc package it is being compiled against.")
g.P("const _ = ", grpcPkg, ".SupportPackageIsVersion", generatedCodeVersion)
g.P()
for i, service := range file.FileDescriptorProto.Service {
g.generateService(file, service, i)
}
}
// GenerateImports generates the import declaration for this file.
func (g *grpc) GenerateImports(file *generator.FileDescriptor) {
}
// reservedClientName records whether a client name is reserved on the client side.
var reservedClientName = map[string]bool{
// TODO: do we need any in gRPC?
}
func unexport(s string) string { return strings.ToLower(s[:1]) + s[1:] }
// deprecationComment is the standard comment added to deprecated
// messages, fields, enums, and enum values.
var deprecationComment = "// Deprecated: Do not use."
// generateService generates all the code for the named service.
func (g *grpc) generateService(file *generator.FileDescriptor, service *pb.ServiceDescriptorProto, index int) {
path := fmt.Sprintf("6,%d", index) // 6 means service.
origServName := service.GetName()
fullServName := origServName
if pkg := file.GetPackage(); pkg != "" {
fullServName = pkg + "." + fullServName
}
servName := generator.CamelCase(origServName)
deprecated := service.GetOptions().GetDeprecated()
g.P()
g.P(fmt.Sprintf(`// %sClient is the client API for %s service.
//
// For semantics around ctx use and closing/ending streaming RPCs, please refer to https://godoc.org/google.golang.org/grpc#ClientConn.NewStream.`, servName, servName))
// Client interface.
if deprecated {
g.P("//")
g.P(deprecationComment)
}
g.P("type ", servName, "Client interface {")
for i, method := range service.Method {
g.gen.PrintComments(fmt.Sprintf("%s,2,%d", path, i)) // 2 means method in a service.
g.P(g.generateClientSignature(servName, method))
}
g.P("}")
g.P()
// Client structure.
g.P("type ", unexport(servName), "Client struct {")
g.P("cc *", grpcPkg, ".ClientConn")
g.P("}")
g.P()
// NewClient factory.
if deprecated {
g.P(deprecationComment)
}
g.P("func New", servName, "Client (cc *", grpcPkg, ".ClientConn) ", servName, "Client {")
g.P("return &", unexport(servName), "Client{cc}")
g.P("}")
g.P()
var methodIndex, streamIndex int
serviceDescVar := "_" + servName + "_serviceDesc"
// Client method implementations.
for _, method := range service.Method {
var descExpr string
if !method.GetServerStreaming() && !method.GetClientStreaming() {
// Unary RPC method
descExpr = fmt.Sprintf("&%s.Methods[%d]", serviceDescVar, methodIndex)
methodIndex++
} else {
// Streaming RPC method
descExpr = fmt.Sprintf("&%s.Streams[%d]", serviceDescVar, streamIndex)
streamIndex++
}
g.generateClientMethod(servName, fullServName, serviceDescVar, method, descExpr)
}
// Server interface.
serverType := servName + "Server"
g.P("// ", serverType, " is the server API for ", servName, " service.")
if deprecated {
g.P("//")
g.P(deprecationComment)
}
g.P("type ", serverType, " interface {")
for i, method := range service.Method {
g.gen.PrintComments(fmt.Sprintf("%s,2,%d", path, i)) // 2 means method in a service.
g.P(g.generateServerSignature(servName, method))
}
g.P("}")
g.P()
// Server Unimplemented struct for forward compatability.
if deprecated {
g.P(deprecationComment)
}
g.generateUnimplementedServer(servName, service)
// Server registration.
if deprecated {
g.P(deprecationComment)
}
g.P("func Register", servName, "Server(s *", grpcPkg, ".Server, srv ", serverType, ") {")
g.P("s.RegisterService(&", serviceDescVar, `, srv)`)
g.P("}")
g.P()
// Server handler implementations.
var handlerNames []string
for _, method := range service.Method {
hname := g.generateServerMethod(servName, fullServName, method)
handlerNames = append(handlerNames, hname)
}
// Service descriptor.
g.P("var ", serviceDescVar, " = ", grpcPkg, ".ServiceDesc {")
g.P("ServiceName: ", strconv.Quote(fullServName), ",")
g.P("HandlerType: (*", serverType, ")(nil),")
g.P("Methods: []", grpcPkg, ".MethodDesc{")
for i, method := range service.Method {
if method.GetServerStreaming() || method.GetClientStreaming() {
continue
}
g.P("{")
g.P("MethodName: ", strconv.Quote(method.GetName()), ",")
g.P("Handler: ", handlerNames[i], ",")
g.P("},")
}
g.P("},")
g.P("Streams: []", grpcPkg, ".StreamDesc{")
for i, method := range service.Method {
if !method.GetServerStreaming() && !method.GetClientStreaming() {
continue
}
g.P("{")
g.P("StreamName: ", strconv.Quote(method.GetName()), ",")
g.P("Handler: ", handlerNames[i], ",")
if method.GetServerStreaming() {
g.P("ServerStreams: true,")
}
if method.GetClientStreaming() {
g.P("ClientStreams: true,")
}
g.P("},")
}
g.P("},")
g.P("Metadata: \"", file.GetName(), "\",")
g.P("}")
g.P()
}
// generateUnimplementedServer creates the unimplemented server struct
func (g *grpc) generateUnimplementedServer(servName string, service *pb.ServiceDescriptorProto) {
serverType := servName + "Server"
g.P("// Unimplemented", serverType, " can be embedded to have forward compatible implementations.")
g.P("type Unimplemented", serverType, " struct {")
g.P("}")
g.P()
// Unimplemented<service_name>Server's concrete methods
for _, method := range service.Method {
g.generateServerMethodConcrete(servName, method)
}
g.P()
}
// generateServerMethodConcrete returns unimplemented methods which ensure forward compatibility
func (g *grpc) generateServerMethodConcrete(servName string, method *pb.MethodDescriptorProto) {
header := g.generateServerSignatureWithParamNames(servName, method)
g.P("func (*Unimplemented", servName, "Server) ", header, " {")
var nilArg string
if !method.GetServerStreaming() && !method.GetClientStreaming() {
nilArg = "nil, "
}
methName := generator.CamelCase(method.GetName())
statusPkg := string(g.gen.AddImport(statusPkgPath))
codePkg := string(g.gen.AddImport(codePkgPath))
g.P("return ", nilArg, statusPkg, `.Errorf(`, codePkg, `.Unimplemented, "method `, methName, ` not implemented")`)
g.P("}")
}
// generateClientSignature returns the client-side signature for a method.
func (g *grpc) generateClientSignature(servName string, method *pb.MethodDescriptorProto) string {
origMethName := method.GetName()
methName := generator.CamelCase(origMethName)
if reservedClientName[methName] {
methName += "_"
}
reqArg := ", in *" + g.typeName(method.GetInputType())
if method.GetClientStreaming() {
reqArg = ""
}
respName := "*" + g.typeName(method.GetOutputType())
if method.GetServerStreaming() || method.GetClientStreaming() {
respName = servName + "_" + generator.CamelCase(origMethName) + "Client"
}
return fmt.Sprintf("%s(ctx %s.Context%s, opts ...%s.CallOption) (%s, error)", methName, contextPkg, reqArg, grpcPkg, respName)
}
func (g *grpc) generateClientMethod(servName, fullServName, serviceDescVar string, method *pb.MethodDescriptorProto, descExpr string) {
sname := fmt.Sprintf("/%s/%s", fullServName, method.GetName())
methName := generator.CamelCase(method.GetName())
inType := g.typeName(method.GetInputType())
outType := g.typeName(method.GetOutputType())
if method.GetOptions().GetDeprecated() {
g.P(deprecationComment)
}
g.P("func (c *", unexport(servName), "Client) ", g.generateClientSignature(servName, method), "{")
if !method.GetServerStreaming() && !method.GetClientStreaming() {
g.P("out := new(", outType, ")")
// TODO: Pass descExpr to Invoke.
g.P(`err := c.cc.Invoke(ctx, "`, sname, `", in, out, opts...)`)
g.P("if err != nil { return nil, err }")
g.P("return out, nil")
g.P("}")
g.P()
return
}
streamType := unexport(servName) + methName + "Client"
g.P("stream, err := c.cc.NewStream(ctx, ", descExpr, `, "`, sname, `", opts...)`)
g.P("if err != nil { return nil, err }")
g.P("x := &", streamType, "{stream}")
if !method.GetClientStreaming() {
g.P("if err := x.ClientStream.SendMsg(in); err != nil { return nil, err }")
g.P("if err := x.ClientStream.CloseSend(); err != nil { return nil, err }")
}
g.P("return x, nil")
g.P("}")
g.P()
genSend := method.GetClientStreaming()
genRecv := method.GetServerStreaming()
genCloseAndRecv := !method.GetServerStreaming()
// Stream auxiliary types and methods.
g.P("type ", servName, "_", methName, "Client interface {")
if genSend {
g.P("Send(*", inType, ") error")
}
if genRecv {
g.P("Recv() (*", outType, ", error)")
}
if genCloseAndRecv {
g.P("CloseAndRecv() (*", outType, ", error)")
}
g.P(grpcPkg, ".ClientStream")
g.P("}")
g.P()
g.P("type ", streamType, " struct {")
g.P(grpcPkg, ".ClientStream")
g.P("}")
g.P()
if genSend {
g.P("func (x *", streamType, ") Send(m *", inType, ") error {")
g.P("return x.ClientStream.SendMsg(m)")
g.P("}")
g.P()
}
if genRecv {
g.P("func (x *", streamType, ") Recv() (*", outType, ", error) {")
g.P("m := new(", outType, ")")
g.P("if err := x.ClientStream.RecvMsg(m); err != nil { return nil, err }")
g.P("return m, nil")
g.P("}")
g.P()
}
if genCloseAndRecv {
g.P("func (x *", streamType, ") CloseAndRecv() (*", outType, ", error) {")
g.P("if err := x.ClientStream.CloseSend(); err != nil { return nil, err }")
g.P("m := new(", outType, ")")
g.P("if err := x.ClientStream.RecvMsg(m); err != nil { return nil, err }")
g.P("return m, nil")
g.P("}")
g.P()
}
}
// generateServerSignatureWithParamNames returns the server-side signature for a method with parameter names.
func (g *grpc) generateServerSignatureWithParamNames(servName string, method *pb.MethodDescriptorProto) string {
origMethName := method.GetName()
methName := generator.CamelCase(origMethName)
if reservedClientName[methName] {
methName += "_"
}
var reqArgs []string
ret := "error"
if !method.GetServerStreaming() && !method.GetClientStreaming() {
reqArgs = append(reqArgs, "ctx "+contextPkg+".Context")
ret = "(*" + g.typeName(method.GetOutputType()) + ", error)"
}
if !method.GetClientStreaming() {
reqArgs = append(reqArgs, "req *"+g.typeName(method.GetInputType()))
}
if method.GetServerStreaming() || method.GetClientStreaming() {
reqArgs = append(reqArgs, "srv "+servName+"_"+generator.CamelCase(origMethName)+"Server")
}
return methName + "(" + strings.Join(reqArgs, ", ") + ") " + ret
}
// generateServerSignature returns the server-side signature for a method.
func (g *grpc) generateServerSignature(servName string, method *pb.MethodDescriptorProto) string {
origMethName := method.GetName()
methName := generator.CamelCase(origMethName)
if reservedClientName[methName] {
methName += "_"
}
var reqArgs []string
ret := "error"
if !method.GetServerStreaming() && !method.GetClientStreaming() {
reqArgs = append(reqArgs, contextPkg+".Context")
ret = "(*" + g.typeName(method.GetOutputType()) + ", error)"
}
if !method.GetClientStreaming() {
reqArgs = append(reqArgs, "*"+g.typeName(method.GetInputType()))
}
if method.GetServerStreaming() || method.GetClientStreaming() {
reqArgs = append(reqArgs, servName+"_"+generator.CamelCase(origMethName)+"Server")
}
return methName + "(" + strings.Join(reqArgs, ", ") + ") " + ret
}
func (g *grpc) generateServerMethod(servName, fullServName string, method *pb.MethodDescriptorProto) string {
methName := generator.CamelCase(method.GetName())
hname := fmt.Sprintf("_%s_%s_Handler", servName, methName)
inType := g.typeName(method.GetInputType())
outType := g.typeName(method.GetOutputType())
if !method.GetServerStreaming() && !method.GetClientStreaming() {
g.P("func ", hname, "(srv interface{}, ctx ", contextPkg, ".Context, dec func(interface{}) error, interceptor ", grpcPkg, ".UnaryServerInterceptor) (interface{}, error) {")
g.P("in := new(", inType, ")")
g.P("if err := dec(in); err != nil { return nil, err }")
g.P("if interceptor == nil { return srv.(", servName, "Server).", methName, "(ctx, in) }")
g.P("info := &", grpcPkg, ".UnaryServerInfo{")
g.P("Server: srv,")
g.P("FullMethod: ", strconv.Quote(fmt.Sprintf("/%s/%s", fullServName, methName)), ",")
g.P("}")
g.P("handler := func(ctx ", contextPkg, ".Context, req interface{}) (interface{}, error) {")
g.P("return srv.(", servName, "Server).", methName, "(ctx, req.(*", inType, "))")
g.P("}")
g.P("return interceptor(ctx, in, info, handler)")
g.P("}")
g.P()
return hname
}
streamType := unexport(servName) + methName + "Server"
g.P("func ", hname, "(srv interface{}, stream ", grpcPkg, ".ServerStream) error {")
if !method.GetClientStreaming() {
g.P("m := new(", inType, ")")
g.P("if err := stream.RecvMsg(m); err != nil { return err }")
g.P("return srv.(", servName, "Server).", methName, "(m, &", streamType, "{stream})")
} else {
g.P("return srv.(", servName, "Server).", methName, "(&", streamType, "{stream})")
}
g.P("}")
g.P()
genSend := method.GetServerStreaming()
genSendAndClose := !method.GetServerStreaming()
genRecv := method.GetClientStreaming()
// Stream auxiliary types and methods.
g.P("type ", servName, "_", methName, "Server interface {")
if genSend {
g.P("Send(*", outType, ") error")
}
if genSendAndClose {
g.P("SendAndClose(*", outType, ") error")
}
if genRecv {
g.P("Recv() (*", inType, ", error)")
}
g.P(grpcPkg, ".ServerStream")
g.P("}")
g.P()
g.P("type ", streamType, " struct {")
g.P(grpcPkg, ".ServerStream")
g.P("}")
g.P()
if genSend {
g.P("func (x *", streamType, ") Send(m *", outType, ") error {")
g.P("return x.ServerStream.SendMsg(m)")
g.P("}")
g.P()
}
if genSendAndClose {
g.P("func (x *", streamType, ") SendAndClose(m *", outType, ") error {")
g.P("return x.ServerStream.SendMsg(m)")
g.P("}")
g.P()
}
if genRecv {
g.P("func (x *", streamType, ") Recv() (*", inType, ", error) {")
g.P("m := new(", inType, ")")
g.P("if err := x.ServerStream.RecvMsg(m); err != nil { return nil, err }")
g.P("return m, nil")
g.P("}")
g.P()
}
return hname
}
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