mgrpc: generate first example service

With this changeset, we have the first end to end generated server and
client. Most of the necessary types are in place and working. There are
a lot of details to work out, but this would be enough for to exercise
the end to end flow.

Signed-off-by: Stephen J Day <stephen.day@docker.com>

Protobuild.toml

@@ -1,6 +1,6 @@
 version = "unstable"
 generator = "gogomgrpc"
-plugins = []
+plugins = ["mgrpc"]
 
 # Control protoc include paths. Below are usually some good defaults, but feel
 # free to try it without them if it works for your project.
@@ -24,6 +24,7 @@ plugins = []
 [packages]
   "gogoproto/gogo.proto" = "github.com/gogo/protobuf/gogoproto"
   "google/protobuf/any.proto" = "github.com/gogo/protobuf/types"
+  "google/protobuf/empty.proto" = "github.com/gogo/protobuf/types"
   "google/protobuf/descriptor.proto" = "github.com/gogo/protobuf/protoc-gen-gogo/descriptor"
   "google/protobuf/field_mask.proto" = "github.com/gogo/protobuf/types"
   "google/protobuf/timestamp.proto" = "github.com/gogo/protobuf/types"

example/example.pb.go

@@ -18,10 +18,13 @@ import proto "github.com/gogo/protobuf/proto"
 import fmt "fmt"
 import math "math"
 import _ "github.com/gogo/protobuf/types"
-import _ "github.com/golang/protobuf/ptypes/empty"
+import google_protobuf1 "github.com/gogo/protobuf/types"
 import _ "github.com/gogo/protobuf/gogoproto"
 import _ "github.com/gogo/protobuf/types"
 
+import context "context"
+import github_com_stevvooe_mgrpc "github.com/stevvooe/mgrpc"
+
 import strings "strings"
 import reflect "reflect"
 
@@ -180,6 +183,42 @@ func encodeVarintExample(dAtA []byte, offset int, v uint64) int {
 	dAtA[offset] = uint8(v)
 	return offset + 1
 }
+
+type ExampleService interface {
+	Method1(ctx context.Context, req *Method1Request) (*Method1Response, error)
+	Method2(ctx context.Context, req *Method1Request) (*google_protobuf1.Empty, error)
+}
+
+func RegisterExampleService(srv *github_com_stevvooe_mgrpc.Server, svc ExampleService) error {
+	return srv.Register("mgrpc.example.v1.Example", map[string]github_com_stevvooe_mgrpc.Handler{
+		"Method1": github_com_stevvooe_mgrpc.HandlerFunc(func(ctx context.Context, req interface{}) (interface{}, error) {
+			return svc.Method1(ctx, req.(*Method1Request))
+		}),
+		"Method2": github_com_stevvooe_mgrpc.HandlerFunc(func(ctx context.Context, req interface{}) (interface{}, error) {
+			return svc.Method2(ctx, req.(*Method1Request))
+		}),
+	})
+}
+
+type ExampleClient struct {
+	client *github_com_stevvooe_mgrpc.Client
+}
+
+func (c *ExampleClient) Method1(ctx context.Context, req *Method1Request) (*Method1Response, error) {
+	resp, err := c.client.Call(ctx, "mgrpc.example.v1.Example", "Method1", req)
+	if err != nil {
+		return nil, err
+	}
+	return resp.(*Method1Response), nil
+}
+
+func (c *ExampleClient) Method2(ctx context.Context, req *Method1Request) (*google_protobuf1.Empty, error) {
+	resp, err := c.client.Call(ctx, "mgrpc.example.v1.Example", "Method2", req)
+	if err != nil {
+		return nil, err
+	}
+	return resp.(*google_protobuf1.Empty), nil
+}
 func (m *Method1Request) Size() (n int) {
 	var l int
 	_ = l

generator.go

@@ -0,0 +1,111 @@
+package mgrpc
+
+import (
+	"github.com/gogo/protobuf/protoc-gen-gogo/descriptor"
+	"github.com/gogo/protobuf/protoc-gen-gogo/generator"
+)
+
+type mgrpcGenerator struct {
+	*generator.Generator
+	generator.PluginImports
+
+	typeurlPkg generator.Single
+	mgrpcPkg   generator.Single
+	contextPkg generator.Single
+}
+
+func init() {
+	generator.RegisterPlugin(new(mgrpcGenerator))
+}
+
+func (p *mgrpcGenerator) Name() string {
+	return "mgrpc"
+}
+
+func (p *mgrpcGenerator) Init(g *generator.Generator) {
+	p.Generator = g
+}
+
+func (p *mgrpcGenerator) Generate(file *generator.FileDescriptor) {
+	p.PluginImports = generator.NewPluginImports(p.Generator)
+	p.contextPkg = p.NewImport("context")
+	p.typeurlPkg = p.NewImport("github.com/containerd/typeurl")
+	p.mgrpcPkg = p.NewImport("github.com/stevvooe/mgrpc")
+
+	for _, service := range file.GetService() {
+		serviceName := service.GetName()
+		if pkg := file.GetPackage(); pkg != "" {
+			serviceName = pkg + "." + serviceName
+		}
+
+		p.genService(serviceName, service)
+	}
+}
+
+func (p *mgrpcGenerator) genService(fullName string, service *descriptor.ServiceDescriptorProto) {
+	serviceName := service.GetName() + "Service"
+	p.P()
+	p.P("type ", serviceName, " interface{")
+	p.In()
+	for _, method := range service.Method {
+		p.P(method.GetName(),
+			"(ctx ", p.contextPkg.Use(), ".Context, ",
+			"req *", p.typeName(method.GetInputType()), ") ",
+			"(*", p.typeName(method.GetOutputType()), ", error)")
+
+	}
+	p.Out()
+	p.P("}")
+
+	p.P()
+	// registration method
+	p.P("func Register", serviceName, "(srv *", p.mgrpcPkg.Use(), ".Server, svc ", serviceName, ") error {")
+	p.In()
+	p.P(`return srv.Register("`, fullName, `", map[string]`, p.mgrpcPkg.Use(), ".Handler{")
+	p.In()
+	for _, method := range service.Method {
+		p.P(`"`, method.GetName(), `": `, p.mgrpcPkg.Use(), `.HandlerFunc(func(ctx context.Context, req interface{}) (interface{}, error) {`)
+		p.In()
+		p.P("return svc.", method.GetName(), "(ctx, req.(*", p.typeName(method.GetInputType()), "))")
+		p.Out()
+		p.P("}),")
+	}
+	p.Out()
+	p.P("})")
+	p.Out()
+	p.P("}")
+
+	clientType := service.GetName() + "Client"
+	p.P()
+	p.P("type ", clientType, " struct{")
+	p.In()
+	p.P("client *", p.mgrpcPkg.Use(), ".Client")
+	p.Out()
+	p.P("}")
+	for _, method := range service.Method {
+		p.P()
+		p.P("func (c *", clientType, ") ", method.GetName(),
+			"(ctx ", p.contextPkg.Use(), ".Context, ",
+			"req *", p.typeName(method.GetInputType()), ") ",
+			"(*", p.typeName(method.GetOutputType()), ", error) {")
+		p.In()
+		p.P("resp, err := c.client.Call(ctx, ", `"`+fullName+`", `, `"`+method.GetName()+`"`, ", req)")
+		p.P("if err != nil {")
+		p.In()
+		p.P("return nil, err")
+		p.Out()
+		p.P("}")
+		p.P("return resp.(*", p.typeName(method.GetOutputType()), "), nil")
+		p.Out()
+		p.P("}")
+	}
+}
+
+func (p *mgrpcGenerator) objectNamed(name string) generator.Object {
+	p.Generator.RecordTypeUse(name)
+	return p.Generator.ObjectNamed(name)
+}
+
+func (p *mgrpcGenerator) typeName(str string) string {
+	return p.Generator.TypeName(p.objectNamed(str))
+}