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@@ -0,0 +1,142 @@ |
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package main |
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import ( |
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"encoding/json" |
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"io" |
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"log" |
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"net/http" |
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"os" |
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"github.com/go-redis/redis" |
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"github.com/gorilla/websocket" |
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"github.com/joho/godotenv" |
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) |
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type ChatMessage struct { |
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Username string `json:"username"` |
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Text string `json:"text"` |
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} |
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var ( |
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rdb *redis.Client |
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) |
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var clients = make(map[*websocket.Conn]bool) |
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var broadcaster = make(chan ChatMessage) |
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var upgrader = websocket.Upgrader{ |
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CheckOrigin: func(r *http.Request) bool { |
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return true |
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}, |
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} |
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func handleConnections(w http.ResponseWriter, r *http.Request) { |
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ws, err := upgrader.Upgrade(w, r, nil) |
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if err != nil { |
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log.Fatal(err) |
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} |
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// ensure connection close when function returns |
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defer ws.Close() |
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clients[ws] = true |
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// if it's zero, no messages were ever sent/saved |
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if rdb.Exists("chat_messages").Val() != 0 { |
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sendPreviousMessages(ws) |
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} |
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for { |
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var msg ChatMessage |
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// Read in a new message as JSON and map it to a Message object |
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err := ws.ReadJSON(&msg) |
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if err != nil { |
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delete(clients, ws) |
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break |
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} |
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// send new message to the channel |
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broadcaster <- msg |
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} |
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} |
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func sendPreviousMessages(ws *websocket.Conn) { |
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chatMessages, err := rdb.LRange("chat_messages", 0, -1).Result() |
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if err != nil { |
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panic(err) |
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} |
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// send previous messages |
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for _, chatMessage := range chatMessages { |
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var msg ChatMessage |
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json.Unmarshal([]byte(chatMessage), &msg) |
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messageClient(ws, msg) |
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} |
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} |
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// If a message is sent while a client is closing, ignore the error |
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func unsafeError(err error) bool { |
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return !websocket.IsCloseError(err, websocket.CloseGoingAway) && err != io.EOF |
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} |
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func handleMessages() { |
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for { |
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// grab any next message from channel |
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msg := <-broadcaster |
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storeInRedis(msg) |
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messageClients(msg) |
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} |
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} |
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func storeInRedis(msg ChatMessage) { |
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json, err := json.Marshal(msg) |
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if err != nil { |
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panic(err) |
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} |
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if err := rdb.RPush("chat_messages", json).Err(); err != nil { |
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panic(err) |
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} |
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} |
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func messageClients(msg ChatMessage) { |
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// send to every client currently connected |
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for client := range clients { |
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messageClient(client, msg) |
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} |
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} |
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func messageClient(client *websocket.Conn, msg ChatMessage) { |
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err := client.WriteJSON(msg) |
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if err != nil && unsafeError(err) { |
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log.Printf("error: %v", err) |
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client.Close() |
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delete(clients, client) |
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} |
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} |
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func main() { |
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env := os.Getenv("GO_ENV") |
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if "" == env { |
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err := godotenv.Load() |
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if err != nil { |
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log.Fatal("Error loading .env file") |
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} |
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} |
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port := os.Getenv("PORT") |
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redisURL := os.Getenv("REDIS_URL") |
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opt, err := redis.ParseURL(redisURL) |
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if err != nil { |
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panic(err) |
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} |
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rdb = redis.NewClient(opt) |
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http.Handle("/", http.FileServer(http.Dir("./public"))) |
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http.HandleFunc("/websocket", handleConnections) |
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go handleMessages() |
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log.Print("Server starting at localhost:" + port) |
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if err := http.ListenAndServe(":"+port, nil); err != nil { |
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log.Fatal(err) |
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} |
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} |
gjtorikian created this gist