advanced-go-programming-book/examples/ch4.4/basic/client/main.go

package main

import (
	"context"
	"fmt"
	"io"
	"log"
	"net"
	"time"

	"google.golang.org/grpc"
)

type HelloServiceImpl struct{}

func (p *HelloServiceImpl) Hello(ctx context.Context, args *String) (*String, error) {
	reply := &String{Value: "hello:" + args.GetValue()}
	return reply, nil
}

func (p *HelloServiceImpl) Channel(stream HelloService_ChannelServer) error {
	for {
		log.Println(111)
		args, err := stream.Recv()
		if err != nil {
			if err == io.EOF {
				return nil
			}
			return err
		}

		reply := &String{Value: "hello:" + args.GetValue()}

		err = stream.Send(reply)
		if err != nil {
			return err
		}
	}
}

func main() {
	go startGrpcServer()
	doClientWork()
}

func startGrpcServer() {
	grpcServer := grpc.NewServer()
	RegisterHelloServiceServer(grpcServer, &HelloServiceImpl{})

	lis, err := net.Listen("tcp", ":1234")
	if err != nil {
		log.Fatal(err)
	}

	grpcServer.Serve(lis)
}

func doClientWork() {
	conn, err := grpc.Dial("localhost:1234", grpc.WithInsecure())
	if err != nil {
		log.Fatal(err)
	}
	defer conn.Close()

	client := NewHelloServiceClient(conn)
	reply, err := client.Hello(context.Background(), &String{Value: "hello"})
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(reply.GetValue())

	stream, err := client.Channel(context.Background())
	if err != nil {
		log.Fatal(err)
	}

	go func() {
		for {
			if err := stream.Send(&String{Value: "hi"}); err != nil {
				log.Fatal(err)
			}

			time.Sleep(time.Second)
		}
	}()

	for {
		log.Println(222)

		reply, err := stream.Recv()
		if err != nil {
			if err == io.EOF {
				break
			}
			log.Fatal(err)
		}

		fmt.Println(reply.GetValue())
	}
}