How to stop golang gRPC server with a function? - c

Question

Looking at the helloworld example from grpc-go, how can I add a StopGrpcServer() function to stop gRPC server?
I'm trying to make a shared C library file of gRPC server which can be used to start and stop the gRPC server by invoking the functions via ffi.
In my tests I am able to start the gRPC server with StartGrpcServer() but I'm feeling lost how to implement StopGrpcServer().
package main
import C
import (
"context"
"log"
"net"
"google.golang.org/grpc"
pb "google.golang.org/grpc/examples/helloworld/helloworld"
)
const (
port = ":50051"
)
// server is used to implement helloworld.GreeterServer.
type server struct {
pb.UnimplementedGreeterServer
}
// SayHello implements helloworld.GreeterServer
func (s *server) SayHello(ctx context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
log.Printf("Received: %v", in.GetName())
return &pb.HelloReply{Message: "Hello " + in.GetName()}, nil
}
//export StopGrpcServer
func (s *server) StopGrpcServer() {
s.Stop()
}
//export StartGrpcServer
func StartGrpcServer() {
lis, err := net.Listen("tcp", port)
if err != nil {
log.Fatalf("failed to listen: %v", err)
}
s := grpc.NewServer()
pb.RegisterGreeterServer(s, &server{})
if err := s.Serve(lis); err != nil {
log.Fatalf("failed to serve: %v", err)
}
}
func main() {}
Would really appreciate some help on it.
Thanks,
Satinder

Answer 1

Thanks for the hint #Marc. I am able to solve the problem by declaring *grpc.Server variable globally outside StartGrpcServer(), and then using it in StopGrpcServer().
Here's the working code:
package main
import C
import (
"context"
"log"
"net"
"google.golang.org/grpc"
pb "google.golang.org/grpc/examples/helloworld/helloworld"
)
var srv *grpc.Server
const (
port = ":50051"
)
// server is used to implement helloworld.GreeterServer.
type server struct {
pb.UnimplementedGreeterServer
}
// SayHello implements helloworld.GreeterServer
func (s *server) SayHello(ctx context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
log.Printf("Received: %v", in.GetName())
return &pb.HelloReply{Message: "Hello " + in.GetName()}, nil
}
//export StopGrpcServer
func StopGrpcServer() {
srv.Stop()
}
//export StartGrpcServer
func StartGrpcServer() {
lis, err := net.Listen("tcp", port)
if err != nil {
log.Fatalf("failed to listen: %v", err)
}
srv = grpc.NewServer()
pb.RegisterGreeterServer(srv, &server{})
if err := srv.Serve(lis); err != nil {
log.Fatalf("failed to serve: %v", err)
}
}
func main() {}
// Compile with command:
// go build -o greeter.so -buildmode=c-shared server.go