cancellation_server.go

func (*server) Greet(ctx context.Context, req *greetpb.GreetRequest) (*greetpb.GreetResponse, error) {
	log.Println("Greet rpc invoked!")

	time.Sleep(500 * time.Millisecond)

	if ctx.Err() == context.Canceled {
		return nil, status.Error(codes.Canceled, "Client cancelled the request")
	}

	first := req.Greeting.FirstName
	return &greetpb.GreetResponse{
		Result: fmt.Sprintf("Hello %s", first),
	}, nil
}