28 Studi Kasus: Streaming Chat Sederhana

syntax = "proto3";

package chat;

message ChatMessage {
  string username = 1;
  string message = 2;
  string timestamp = 3;
}

service ChatService {
  rpc ChatStream(stream ChatMessage) returns (stream ChatMessage);
}

package main

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

	pb "yourmodule/chat"
	"google.golang.org/grpc"
)

type chatServer struct {
	pb.UnimplementedChatServiceServer
	mu      sync.Mutex
	clients map[string]pb.ChatService_ChatStreamServer
	msgs    []pb.ChatMessage
}

func (s *chatServer) ChatStream(stream pb.ChatService_ChatStreamServer) error {
	id := fmt.Sprintf("client-%d", time.Now().UnixNano())
	s.mu.Lock()
	s.clients[id] = stream
	for _, msg := range s.msgs {
		stream.Send(&msg)
	}
	s.mu.Unlock()

	defer func() {
		s.mu.Lock()
		delete(s.clients, id)
		s.mu.Unlock()
	}()

	for {
		msg, err := stream.Recv()
		if err != nil {
			log.Printf("client %s disconnected", id)
			return err
		}

		msg.Timestamp = time.Now().Format(time.RFC3339)
		s.mu.Lock()
		s.msgs = append(s.msgs, *msg)
		for _, c := range s.clients {
			if err := c.Send(msg); err != nil {
				log.Println("send error:", err)
			}
		}
		s.mu.Unlock()
	}
}

func main() {
	lis, err := net.Listen("tcp", ":50051")
	if err != nil {
		log.Fatalf("failed to listen: %v", err)
	}
	server := grpc.NewServer()
	pb.RegisterChatServiceServer(server, &chatServer{
		clients: make(map[string]pb.ChatService_ChatStreamServer),
	})
	log.Println("gRPC chat server started on :50051")
	server.Serve(lis)
}

package main

import (
	"context"
	"fmt"
	"log"
	"time"

	pb "yourmodule/chat"
	"google.golang.org/grpc"
)

func main() {
	conn, err := grpc.Dial("localhost:50051", grpc.WithInsecure())
	if err != nil {
		log.Fatalf("fail connect: %v", err)
	}
	defer conn.Close()

	client := pb.NewChatServiceClient(conn)
	stream, err := client.ChatStream(context.Background())
	if err != nil {
		log.Fatalf("fail stream: %v", err)
	}

	// Receive stream
	go func() {
		for {
			msg, err := stream.Recv()
			if err != nil {
				log.Fatal(err)
			}
			fmt.Printf("[%s] %s: %s\n", msg.Timestamp, msg.Username, msg.Message)
		}
	}()

	// Send messages
	for {
		var text string
		fmt.Print("> ")
		fmt.Scanln(&text)
		stream.Send(&pb.ChatMessage{
			Username: "ihsan",
			Message:  text,
		})
	}
}