[Go] Working on a go example plus fixing go grpc code (#6448)

Implemented server.go and half implemented client.go

Finishes implementation for greeter go example

Update grpc code for monster.fbs

Adds a couple of cpp methods

Adhere to gofmt standards

Adds a readme for issues with grpc

grpc/examples/README.md

@@ -0,0 +1,7 @@
+## Languages known issues
+
+### Go
+
+- Always requires the `content-type` of the payload to be set to `application/grpc+flatbuffers`
+
+example: `.SayHello(ctx, b, grpc.CallContentSubtype("flatbuffers"))`

grpc/examples/generate.sh

@@ -0,0 +1,18 @@
+current_dir=`pwd`
+
+cd ../..
+
+main_dir=`pwd`
+
+cd ${current_dir}
+
+alias fbc='${main_dir}/Debug/flatc'
+generator="--grpc $current_dir/greeter.fbs"
+
+# Regenerate Go lang code
+cd go/
+
+cd greeter
+fbc --go ${generator}
+
+cd ../..

grpc/examples/go/greeter/.gitignore

@@ -0,0 +1,2 @@
+**/server
+**/client

grpc/examples/go/greeter/README.md

@@ -0,0 +1,25 @@
+# Go Greeter example
+
+## Project Structure
+
+    .
+    ├── server                   # Server module
+    ├── client                   # Client module
+    ├── models                   # Flatbuffers models & main grpc code.
+    └── README.md
+
+## How to run Server:
+
+- `cd server`
+
+- `go clean`
+
+- `go run main.go`
+
+## How to run Client:
+
+- `cd client`
+
+- `go clean`
+
+- `go run main.go --name NAME`

grpc/examples/go/greeter/client/go.mod

@@ -0,0 +1,11 @@
+module github.com/google/flatbuffers/grpc/examples/go/greeter/client
+
+go 1.15
+
+replace github.com/google/flatbuffers/grpc/examples/go/greeter/models v0.0.0 => ../models
+
+require (
+	github.com/google/flatbuffers v1.12.0
+	github.com/google/flatbuffers/grpc/examples/go/greeter/models v0.0.0
+	google.golang.org/grpc v1.35.0
+)

grpc/examples/go/greeter/client/main.go

@@ -0,0 +1,74 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"io"
+	"log"
+	"time"
+
+	flatbuffers "github.com/google/flatbuffers/go"
+	models "github.com/google/flatbuffers/grpc/examples/go/greeter/models"
+	"google.golang.org/grpc"
+)
+
+var (
+	addr = "3000"
+	name = flag.String("name", "Flatbuffers", "name to be sent to server :D")
+)
+
+func printSayHello(client models.GreeterClient, name string) {
+	log.Printf("Name to be sent (%s)", name)
+	b := flatbuffers.NewBuilder(0)
+	i := b.CreateString(name)
+	models.HelloRequestStart(b)
+	models.HelloRequestAddName(b, i)
+	b.Finish(models.HelloRequestEnd(b))
+
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	request, err := client.SayHello(ctx, b, grpc.CallContentSubtype("flatbuffers"))
+	if err != nil {
+		log.Fatalf("%v.SayHello(_) = _, %v: ", client, err)
+	}
+	log.Printf("server said %q", request.Message())
+}
+
+func printSayManyHello(client models.GreeterClient, name string) {
+	log.Printf("Name to be sent (%s)", name)
+	b := flatbuffers.NewBuilder(0)
+	i := b.CreateString(name)
+	models.HelloRequestStart(b)
+	models.HelloRequestAddName(b, i)
+	b.Finish(models.HelloRequestEnd(b))
+
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	stream, err := client.SayManyHellos(ctx, b, grpc.CallContentSubtype("flatbuffers"))
+	if err != nil {
+		log.Fatalf("%v.SayManyHellos(_) = _, %v", client, err)
+	}
+	for {
+		request, err := stream.Recv()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			log.Fatalf("%v.SayManyHellos(_) = _, %v", client, err)
+		}
+		log.Printf("server said %q", request.Message())
+	}
+}
+
+func main() {
+	flag.Parse()
+	conn, err := grpc.Dial(fmt.Sprintf("localhost:%d", 3000), grpc.WithInsecure(), grpc.WithCodec(flatbuffers.FlatbuffersCodec{}))
+	if err != nil {
+		log.Fatalf("fail to dial: %v", err)
+	}
+	defer conn.Close()
+	client := models.NewGreeterClient(conn)
+	printSayHello(client, *name)
+	printSayManyHello(client, *name)
+}

grpc/examples/go/greeter/models/Greeter_grpc.go

@@ -0,0 +1,158 @@
+//Generated by gRPC Go plugin
+//If you make any local changes, they will be lost
+//source: greeter
+
+package models
+
+import (
+	context "context"
+	flatbuffers "github.com/google/flatbuffers/go"
+	grpc "google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+// Client API for Greeter service
+type GreeterClient interface {
+	SayHello(ctx context.Context, in *flatbuffers.Builder,
+		opts ...grpc.CallOption) (*HelloReply, error)
+	SayManyHellos(ctx context.Context, in *flatbuffers.Builder,
+		opts ...grpc.CallOption) (Greeter_SayManyHellosClient, error)
+}
+
+type greeterClient struct {
+	cc grpc.ClientConnInterface
+}
+
+func NewGreeterClient(cc grpc.ClientConnInterface) GreeterClient {
+	return &greeterClient{cc}
+}
+
+func (c *greeterClient) SayHello(ctx context.Context, in *flatbuffers.Builder,
+	opts ...grpc.CallOption) (*HelloReply, error) {
+	out := new(HelloReply)
+	err := c.cc.Invoke(ctx, "/models.Greeter/SayHello", in, out, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *greeterClient) SayManyHellos(ctx context.Context, in *flatbuffers.Builder,
+	opts ...grpc.CallOption) (Greeter_SayManyHellosClient, error) {
+	stream, err := c.cc.NewStream(ctx, &_Greeter_serviceDesc.Streams[0], "/models.Greeter/SayManyHellos", opts...)
+	if err != nil {
+		return nil, err
+	}
+	x := &greeterSayManyHellosClient{stream}
+	if err := x.ClientStream.SendMsg(in); err != nil {
+		return nil, err
+	}
+	if err := x.ClientStream.CloseSend(); err != nil {
+		return nil, err
+	}
+	return x, nil
+}
+
+type Greeter_SayManyHellosClient interface {
+	Recv() (*HelloReply, error)
+	grpc.ClientStream
+}
+
+type greeterSayManyHellosClient struct {
+	grpc.ClientStream
+}
+
+func (x *greeterSayManyHellosClient) Recv() (*HelloReply, error) {
+	m := new(HelloReply)
+	if err := x.ClientStream.RecvMsg(m); err != nil {
+		return nil, err
+	}
+	return m, nil
+}
+
+// Server API for Greeter service
+type GreeterServer interface {
+	SayHello(context.Context, *HelloRequest) (*flatbuffers.Builder, error)
+	SayManyHellos(*HelloRequest, Greeter_SayManyHellosServer) error
+	mustEmbedUnimplementedGreeterServer()
+}
+
+type UnimplementedGreeterServer struct {
+}
+
+func (UnimplementedGreeterServer) SayHello(context.Context, *HelloRequest) (*flatbuffers.Builder, error) {
+	return nil, status.Errorf(codes.Unimplemented, "method SayHello not implemented")
+}
+
+func (UnimplementedGreeterServer) SayManyHellos(*HelloRequest, Greeter_SayManyHellosServer) error {
+	return status.Errorf(codes.Unimplemented, "method SayManyHellos not implemented")
+}
+
+func (UnimplementedGreeterServer) mustEmbedUnimplementedGreeterServer() {}
+
+type UnsafeGreeterServer interface {
+	mustEmbedUnimplementedGreeterServer()
+}
+
+func RegisterGreeterServer(s grpc.ServiceRegistrar, srv GreeterServer) {
+	s.RegisterService(&_Greeter_serviceDesc, srv)
+}
+
+func _Greeter_SayHello_Handler(srv interface{}, ctx context.Context,
+	dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(HelloRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(GreeterServer).SayHello(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/models.Greeter/SayHello",
+	}
+
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(GreeterServer).SayHello(ctx, req.(*HelloRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+func _Greeter_SayManyHellos_Handler(srv interface{}, stream grpc.ServerStream) error {
+	m := new(HelloRequest)
+	if err := stream.RecvMsg(m); err != nil {
+		return err
+	}
+	return srv.(GreeterServer).SayManyHellos(m, &greeterSayManyHellosServer{stream})
+}
+
+type Greeter_SayManyHellosServer interface {
+	Send(*flatbuffers.Builder) error
+	grpc.ServerStream
+}
+
+type greeterSayManyHellosServer struct {
+	grpc.ServerStream
+}
+
+func (x *greeterSayManyHellosServer) Send(m *flatbuffers.Builder) error {
+	return x.ServerStream.SendMsg(m)
+}
+
+var _Greeter_serviceDesc = grpc.ServiceDesc{
+	ServiceName: "models.Greeter",
+	HandlerType: (*GreeterServer)(nil),
+	Methods: []grpc.MethodDesc{
+		{
+			MethodName: "SayHello",
+			Handler:    _Greeter_SayHello_Handler,
+		},
+	},
+	Streams: []grpc.StreamDesc{
+		{
+			StreamName:    "SayManyHellos",
+			Handler:       _Greeter_SayManyHellos_Handler,
+			ServerStreams: true,
+		},
+	},
+}

grpc/examples/go/greeter/models/HelloReply.go

@@ -0,0 +1,52 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package models
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+)
+
+type HelloReply struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsHelloReply(buf []byte, offset flatbuffers.UOffsetT) *HelloReply {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &HelloReply{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func GetSizePrefixedRootAsHelloReply(buf []byte, offset flatbuffers.UOffsetT) *HelloReply {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &HelloReply{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func (rcv *HelloReply) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *HelloReply) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *HelloReply) Message() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func HelloReplyStart(builder *flatbuffers.Builder) {
+	builder.StartObject(1)
+}
+func HelloReplyAddMessage(builder *flatbuffers.Builder, message flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(0, flatbuffers.UOffsetT(message), 0)
+}
+func HelloReplyEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

grpc/examples/go/greeter/models/HelloRequest.go

@@ -0,0 +1,52 @@
+// Code generated by the FlatBuffers compiler. DO NOT EDIT.
+
+package models
+
+import (
+	flatbuffers "github.com/google/flatbuffers/go"
+)
+
+type HelloRequest struct {
+	_tab flatbuffers.Table
+}
+
+func GetRootAsHelloRequest(buf []byte, offset flatbuffers.UOffsetT) *HelloRequest {
+	n := flatbuffers.GetUOffsetT(buf[offset:])
+	x := &HelloRequest{}
+	x.Init(buf, n+offset)
+	return x
+}
+
+func GetSizePrefixedRootAsHelloRequest(buf []byte, offset flatbuffers.UOffsetT) *HelloRequest {
+	n := flatbuffers.GetUOffsetT(buf[offset+flatbuffers.SizeUint32:])
+	x := &HelloRequest{}
+	x.Init(buf, n+offset+flatbuffers.SizeUint32)
+	return x
+}
+
+func (rcv *HelloRequest) Init(buf []byte, i flatbuffers.UOffsetT) {
+	rcv._tab.Bytes = buf
+	rcv._tab.Pos = i
+}
+
+func (rcv *HelloRequest) Table() flatbuffers.Table {
+	return rcv._tab
+}
+
+func (rcv *HelloRequest) Name() []byte {
+	o := flatbuffers.UOffsetT(rcv._tab.Offset(4))
+	if o != 0 {
+		return rcv._tab.ByteVector(o + rcv._tab.Pos)
+	}
+	return nil
+}
+
+func HelloRequestStart(builder *flatbuffers.Builder) {
+	builder.StartObject(1)
+}
+func HelloRequestAddName(builder *flatbuffers.Builder, name flatbuffers.UOffsetT) {
+	builder.PrependUOffsetTSlot(0, flatbuffers.UOffsetT(name), 0)
+}
+func HelloRequestEnd(builder *flatbuffers.Builder) flatbuffers.UOffsetT {
+	return builder.EndObject()
+}

grpc/examples/go/greeter/models/go.mod

@@ -0,0 +1,8 @@
+module github.com/google/flatbuffers/grpc/examples/go/greeter/models
+
+go 1.15
+
+require (
+	github.com/google/flatbuffers v1.12.0
+	google.golang.org/grpc v1.35.0
+)

grpc/examples/go/greeter/server/go.mod

@@ -0,0 +1,11 @@
+module github.com/google/flatbuffers/grpc/examples/go/greeter/server
+
+go 1.15
+
+replace github.com/google/flatbuffers/grpc/examples/go/greeter/models v0.0.0 => ../models
+
+require (
+	github.com/google/flatbuffers v1.12.0
+	github.com/google/flatbuffers/grpc/examples/go/greeter/models v0.0.0
+	google.golang.org/grpc v1.35.0
+)

grpc/examples/go/greeter/server/main.go

@@ -0,0 +1,78 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"net"
+
+	flatbuffers "github.com/google/flatbuffers/go"
+	models "github.com/google/flatbuffers/grpc/examples/go/greeter/models"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/encoding"
+)
+
+var (
+	greetings = [...]string{"Hi", "Hallo", "Ciao"}
+)
+
+type greeterServer struct {
+	models.UnimplementedGreeterServer
+}
+
+func (s *greeterServer) SayHello(ctx context.Context, request *models.HelloRequest) (*flatbuffers.Builder, error) {
+	v := request.Name()
+	var m string
+	if v == nil {
+		m = "Unknown"
+	} else {
+		m = string(v)
+	}
+	b := flatbuffers.NewBuilder(0)
+	idx := b.CreateString("welcome " + m)
+	models.HelloReplyStart(b)
+	models.HelloReplyAddMessage(b, idx)
+	b.Finish(models.HelloReplyEnd(b))
+	return b, nil
+}
+
+func (s *greeterServer) SayManyHellos(request *models.HelloRequest, stream models.Greeter_SayManyHellosServer) error {
+	v := request.Name()
+	var m string
+	if v == nil {
+		m = "Unknown"
+	} else {
+		m = string(v)
+	}
+	b := flatbuffers.NewBuilder(0)
+
+	for _, greeting := range greetings {
+		idx := b.CreateString(greeting + " " + m)
+		models.HelloReplyStart(b)
+		models.HelloReplyAddMessage(b, idx)
+		b.Finish(models.HelloReplyEnd(b))
+		if err := stream.Send(b); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func newServer() *greeterServer {
+	s := &greeterServer{}
+	return s
+}
+
+func main() {
+	lis, err := net.Listen("tcp", fmt.Sprintf("localhost:%d", 3000))
+	if err != nil {
+		log.Fatalf("failed to listen: %v", err)
+	}
+	grpcServer := grpc.NewServer()
+	encoding.RegisterCodec(flatbuffers.FlatbuffersCodec{})
+	models.RegisterGreeterServer(grpcServer, newServer())
+	if err := grpcServer.Serve(lis); err != nil {
+		fmt.Print(err)
+		panic(err)
+	}
+}

grpc/examples/greeter.fbs

@@ -0,0 +1,14 @@
+namespace models;
+
+table HelloReply {
+  message:string;
+}
+
+table HelloRequest {
+  name:string;
+}
+
+rpc_service Greeter {
+  SayHello(HelloRequest):HelloReply;
+  SayManyHellos(HelloRequest):HelloReply (streaming: "server");
+}