basic

apps/api/cmd/broadcaster.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"log"
+	"time"
+
+	"github.com/redis/go-redis/v9"
+)
+
+type Broadcaster struct {
+  hub *Hub
+  cache *redis.Client
+  state *string
+}
+
+func newBroadcaster(hub *Hub, cache *redis.Client) Broadcaster {
+  return Broadcaster{
+    hub: hub,
+    cache: cache,
+    state: nil,
+  }
+}
+
+func (b *Broadcaster) run() {
+  for {
+    time.Sleep(5 * time.Second)
+    ctx := context.Background()
+    state, err := b.cache.Get(ctx, "s:state").Result()
+    if err != nil {
+      if errors.Is(err, redis.Nil) {
+        continue
+      }
+      log.Printf("[ERROR] broadcaster: %v", err)
+      continue
+    }
+    if b.state == nil || *b.state != state {
+      b.state = &state
+      b.hub.broadcast <- []byte(state)
+    }
+  }
+}
+

apps/api/cmd/client.go

@@ -0,0 +1,134 @@
+package main
+
+import (
+	"bytes"
+	"log"
+	"net/http"
+	"time"
+
+	"github.com/gorilla/websocket"
+)
+
+const (
+	// Time allowed to write a message to the peer.
+	writeWait = 10 * time.Second
+
+	// Time allowed to read the next pong message from the peer.
+	pongWait = 60 * time.Second
+
+	// Send pings to peer with this period. Must be less than pongWait.
+	pingPeriod = (pongWait * 9) / 10
+
+	// Maximum message size allowed from peer.
+	maxMessageSize = 512
+)
+
+var (
+	newline = []byte{'\n'}
+	space   = []byte{' '}
+)
+
+var upgrader = websocket.Upgrader{
+	ReadBufferSize:  1024,
+	WriteBufferSize: 1024,
+}
+
+// Client is a middleman between the websocket connection and the hub.
+type Client struct {
+	hub *Hub
+
+	// The websocket connection.
+	conn *websocket.Conn
+
+	// Buffered channel of outbound messages.
+	send chan []byte
+}
+
+// readPump pumps messages from the websocket connection to the hub.
+//
+// The application runs readPump in a per-connection goroutine. The application
+// ensures that there is at most one reader on a connection by executing all
+// reads from this goroutine.
+func (c *Client) readPump() {
+	defer func() {
+		c.hub.unregister <- c
+		c.conn.Close()
+	}()
+	c.conn.SetReadLimit(maxMessageSize)
+	c.conn.SetReadDeadline(time.Now().Add(pongWait))
+	c.conn.SetPongHandler(func(string) error { c.conn.SetReadDeadline(time.Now().Add(pongWait)); return nil })
+	for {
+		_, message, err := c.conn.ReadMessage()
+		if err != nil {
+			if websocket.IsUnexpectedCloseError(err, websocket.CloseGoingAway, websocket.CloseAbnormalClosure) {
+				log.Printf("error: %v", err)
+			}
+			break
+		}
+		message = bytes.TrimSpace(bytes.Replace(message, newline, space, -1))
+		c.hub.broadcast <- message
+	}
+}
+
+// writePump pumps messages from the hub to the websocket connection.
+//
+// A goroutine running writePump is started for each connection. The
+// application ensures that there is at most one writer to a connection by
+// executing all writes from this goroutine.
+func (c *Client) writePump() {
+	ticker := time.NewTicker(pingPeriod)
+	defer func() {
+		ticker.Stop()
+		c.conn.Close()
+	}()
+	for {
+		select {
+		case message, ok := <-c.send:
+			c.conn.SetWriteDeadline(time.Now().Add(writeWait))
+			if !ok {
+				// The hub closed the channel.
+				c.conn.WriteMessage(websocket.CloseMessage, []byte{})
+				return
+			}
+
+			w, err := c.conn.NextWriter(websocket.TextMessage)
+			if err != nil {
+				return
+			}
+			w.Write(message)
+
+			// Add queued chat messages to the current websocket message.
+			n := len(c.send)
+			for i := 0; i < n; i++ {
+				w.Write(newline)
+				w.Write(<-c.send)
+			}
+
+			if err := w.Close(); err != nil {
+				return
+			}
+		case <-ticker.C:
+			c.conn.SetWriteDeadline(time.Now().Add(writeWait))
+			if err := c.conn.WriteMessage(websocket.PingMessage, nil); err != nil {
+				return
+			}
+		}
+	}
+}
+
+// serveWs handles websocket requests from the peer.
+func serveWs(hub *Hub, w http.ResponseWriter, r *http.Request) {
+	conn, err := upgrader.Upgrade(w, r, nil)
+	if err != nil {
+		log.Println(err)
+		return
+	}
+	client := &Client{hub: hub, conn: conn, send: make(chan []byte, 256)}
+	client.hub.register <- client
+
+	// Allow collection of memory referenced by the caller by doing all work in
+	// new goroutines.
+	go client.writePump()
+	go client.readPump()
+}
+

apps/api/cmd/hub.go

@@ -0,0 +1,49 @@
+package main
+
+// Hub maintains the set of active clients and broadcasts messages to the
+// clients.
+type Hub struct {
+	// Registered clients.
+	clients map[*Client]bool
+
+	// Inbound messages from the clients.
+	broadcast chan []byte
+
+	// Register requests from the clients.
+	register chan *Client
+
+	// Unregister requests from clients.
+	unregister chan *Client
+}
+
+func newHub() *Hub {
+	return &Hub{
+		broadcast:  make(chan []byte),
+		register:   make(chan *Client),
+		unregister: make(chan *Client),
+		clients:    make(map[*Client]bool),
+	}
+}
+
+func (h *Hub) run() {
+	for {
+		select {
+		case client := <-h.register:
+			h.clients[client] = true
+		case client := <-h.unregister:
+			if _, ok := h.clients[client]; ok {
+				delete(h.clients, client)
+				close(client.send)
+			}
+		case message := <-h.broadcast:
+			for client := range h.clients {
+				select {
+				case client.send <- message:
+				default:
+					close(client.send)
+					delete(h.clients, client)
+				}
+			}
+		}
+	}
+}

apps/api/cmd/main.go

@@ -1,25 +1,49 @@
 package main
 
 import (
-	"fmt"
+	"flag"
 	"log"
 	"net/http"
+	"time"
+
+	"github.com/redis/go-redis/v9"
 )
 
-func handle(w http.ResponseWriter, r *http.Request) {
-	log.Println("Received a request at my domain")
-	w.Write([]byte("Hello, Domain name!"))
+var addr = flag.String("addr", ":8080", "http service address")
+
+func serveHome(w http.ResponseWriter, r *http.Request) {
+	log.Println(r.URL)
+	if r.URL.Path != "/" {
+		http.Error(w, "Not found", http.StatusNotFound)
+		return
+	}
+	if r.Method != http.MethodGet {
+		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+	http.ServeFile(w, r, "home.html")
 }
 
 func main() {
-	router := http.NewServeMux()
-	router.HandleFunc("/", handle)
-
-	server := http.Server{
-		Addr:    ":8080",
-		Handler: router,
+	flag.Parse()
+  conn := redis.NewClient(&redis.Options{
+		Addr:     "localhost:6379",
+		Password: "",
+	})
+	hub := newHub()
+  broadcaster := newBroadcaster(hub, conn)
+	go hub.run()
+  go broadcaster.run()
+	http.HandleFunc("/", serveHome)
+	http.HandleFunc("/ws", func(w http.ResponseWriter, r *http.Request) {
+		serveWs(hub, w, r)
+	})
+	server := &http.Server{
+		Addr:              *addr,
+		ReadHeaderTimeout: 3 * time.Second,
+	}
+	err := server.ListenAndServe()
+	if err != nil {
+		log.Fatal("ListenAndServe: ", err)
 	}
-
-	fmt.Println("Server listening on port :8080")
-	server.ListenAndServe()
 }

apps/api/docker-compose.yaml

@@ -0,0 +1,9 @@
+version: '3.9'
+
+services:
+  redis:
+    image: redis:7.2.4-bookworm
+    container_name: redis
+    ports:
+      - 6379:6379
+

apps/api/go.mod

@@ -1,3 +1,14 @@
 module github.com/isd-sgcu/cutu-2024
 
 go 1.22.1
+
+require (
+	github.com/gorilla/websocket v1.5.1
+	github.com/redis/go-redis/v9 v9.5.1
+)
+
+require (
+	github.com/cespare/xxhash/v2 v2.2.0 // indirect
+	github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f // indirect
+	golang.org/x/net v0.17.0 // indirect
+)

apps/api/go.sum

@@ -0,0 +1,14 @@
+github.com/bsm/ginkgo/v2 v2.12.0 h1:Ny8MWAHyOepLGlLKYmXG4IEkioBysk6GpaRTLC8zwWs=
+github.com/bsm/ginkgo/v2 v2.12.0/go.mod h1:SwYbGRRDovPVboqFv0tPTcG1sN61LM1Z4ARdbAV9g4c=
+github.com/bsm/gomega v1.27.10 h1:yeMWxP2pV2fG3FgAODIY8EiRE3dy0aeFYt4l7wh6yKA=
+github.com/bsm/gomega v1.27.10/go.mod h1:JyEr/xRbxbtgWNi8tIEVPUYZ5Dzef52k01W3YH0H+O0=
+github.com/cespare/xxhash/v2 v2.2.0 h1:DC2CZ1Ep5Y4k3ZQ899DldepgrayRUGE6BBZ/cd9Cj44=
+github.com/cespare/xxhash/v2 v2.2.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
+github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f h1:lO4WD4F/rVNCu3HqELle0jiPLLBs70cWOduZpkS1E78=
+github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f/go.mod h1:cuUVRXasLTGF7a8hSLbxyZXjz+1KgoB3wDUb6vlszIc=
+github.com/gorilla/websocket v1.5.1 h1:gmztn0JnHVt9JZquRuzLw3g4wouNVzKL15iLr/zn/QY=
+github.com/gorilla/websocket v1.5.1/go.mod h1:x3kM2JMyaluk02fnUJpQuwD2dCS5NDG2ZHL0uE0tcaY=
+github.com/redis/go-redis/v9 v9.5.1 h1:H1X4D3yHPaYrkL5X06Wh6xNVM/pX0Ft4RV0vMGvLBh8=
+github.com/redis/go-redis/v9 v9.5.1/go.mod h1:hdY0cQFCN4fnSYT6TkisLufl/4W5UIXyv0b/CLO2V2M=
+golang.org/x/net v0.17.0 h1:pVaXccu2ozPjCXewfr1S7xza/zcXTity9cCdXQYSjIM=
+golang.org/x/net v0.17.0/go.mod h1:NxSsAGuq816PNPmqtQdLE42eU2Fs7NoRIZrHJAlaCOE=