Implemented latency measuring

Author: coder-pm

package-lock.json

@@ -2,16 +2,18 @@
   "name": "battle-city-react-server",
   "private": true,
   "dependencies": {
+    "lodash.debounce": "^4.0.8",
     "socket.io": "^2.2.0",
     "uuid": "^3.3.2"
   },
   "devDependencies": {
-    "@types/node": "^11.13.7",
+    "@types/lodash.debounce": "^4.0.6",
+    "@types/node": "^11.13.10",
     "@types/socket.io": "^2.1.2",
     "@types/uuid": "^3.4.4",
-    "nodemon": "^1.18.11",
+    "nodemon": "^1.19.0",
     "ts-node": "^8.1.0",
-    "typescript": "^3.4.4"
+    "typescript": "^3.4.5"
   },
   "scripts": {
     "start": "npm run build:live",

package.json

@@ -6,6 +6,8 @@ export enum NetworkPacket {
     CONNECT_ERROR = 'connect_error',
     DISCONNECT = 'disconnect',
     GAME_HANDSHAKING = 'game.handshaking',
+    GAME_PING = 'game.ping',
+    GAME_PONG = 'game.pong',
     BOARD_STATE_OBSTACLES = 'board.state.obstacles',
     BOARD_STATE_TANKS = 'board.state.tanks',
     BOARD_STATE_MISSILES = 'board.state.missiles',

src/game/enums/NetworkPacket.ts

@@ -1,6 +1,7 @@
 import {GAME_FRAMERATE, GAME_SERVER_ADDRESS, GAME_SERVER_PORT, TANK_HEIGHT, TANK_WIDTH} from "../../../constants";
 import World from "../../../game/classes/World";
 import uuidv4 from 'uuid/v4';
+import debounce from 'lodash.debounce';
 import SocketIO from 'socket.io';
 import http, {Server} from "http";
 import {NetworkPacket} from "../../../game/enums/NetworkPacket";
@@ -128,6 +129,19 @@ export default class Game {
 
                 // send tank list to all players
                 this.io.emit(NetworkPacket.BOARD_STATE_TANKS, Object.values(this.tanks));
+
+                // start measuring of latency
+                let lastPing = new Date().getTime();
+                let latency = 0;
+                const pingFn = debounce(() => {
+                    socket.emit(NetworkPacket.GAME_PING, latency);
+                    lastPing = new Date().getTime();
+                }, 1000);
+                socket.on(NetworkPacket.GAME_PONG, () => {
+                    latency = new Date().getTime() - lastPing;
+                    pingFn();
+                });
+                pingFn();
             } else {
                 socket.emit(NetworkPacket.GAME_HANDSHAKING, {clientId: null, status: HandshakingStatus.FULL});
             }