feat(socket): use round robin for endpoints when the connection fails

src/Client.spec.ts

@@ -11,7 +11,7 @@ setWebSocket(WebSocket);
 const port = process.env.SERVER_PORT || 1339;
 
 describe('client', () => {
-    const url = `ws://127.0.0.1:${port}/`;
+    const urls = [`ws://127.0.0.1:${port}/`];
     let client: Client;
     let server: WebSocket.Server;
     let ws: WebSocket;
@@ -24,7 +24,7 @@ describe('client', () => {
     }
 
     const socketOptions = {
-        url,
+        urls,
     };
     function createClient(): Client {
         return new Client(ClientType.GameClient);

src/GameClient.ts

@@ -58,7 +58,7 @@ export class GameClient extends Client {
             .then(endpoints => {
                 return super.open({
                     authToken: options.authToken,
-                    url: endpoints[0].address,
+                    urls: endpoints.map(({ address }) => address),
                     extraHeaders: extraHeaders,
                 });
             });

src/ParticipantClient.ts

@@ -31,7 +31,7 @@ export class ParticipantClient extends Client {
 
     public open(options: IParticipantOptions): Promise<this> {
         return super.open({
-            url: options.url,
+            urls: [options.url],
             reconnectChecker: options.reconnectChecker,
             queryParams: {
                 'x-protocol-version': '2.0',

src/wire/Socket.spec.ts

@@ -28,7 +28,7 @@ describe('socket', () => {
     let server: WebSocketModule.Server;
     let socket: InteractiveSocket;
 
-    const url = `ws://127.0.0.1:${port}/`;
+    const urls = [`ws://127.0.0.1:${port}/`];
 
     beforeEach(ready => {
         server = new WebSocketModule.Server({ port }, ready);
@@ -45,7 +45,7 @@ describe('socket', () => {
 
     describe('connecting', () => {
         it('connects with no auth', done => {
-            socket = new InteractiveSocket({ url }).connect();
+            socket = new InteractiveSocket({ urls }).connect();
             server.on('connection', (ws: WebSocketModule) => {
                 expect(ws.upgradeReq.url).to.equal('/');
                 expect(ws.upgradeReq.headers.authorization).to.equal(
@@ -59,7 +59,7 @@ describe('socket', () => {
 
         it('connects with an OAuth token', done => {
             socket = new InteractiveSocket({
-                url,
+                urls,
                 authToken: 'asdf!',
             }).connect();
             server.on('connection', (ws: WebSocketModule) => {
@@ -126,7 +126,7 @@ describe('socket', () => {
             checker = sinon.stub();
             checker.resolves();
             socket = new InteractiveSocket({
-                url,
+                urls,
                 pingInterval: 100,
                 replyTimeout: 50,
             }).connect();
@@ -176,6 +176,28 @@ describe('socket', () => {
             });
         });
 
+        it('reconnects to the next server on disconnection', done => {
+            socket.setOptions({ urls: [...urls, `ws://127.0.0.1:${port + 1}/`] });
+
+            // Connect to the first server.
+            socket.once('open', () => {
+                const fallbackServer = new WebSocketModule.Server({ port: port + 1 }, () => {
+                    closeNormal(ws);
+
+                    // Connect to the second server.
+                    fallbackServer.once('connection', (ws2: WebSocketModule) => {
+                        closeNormal(ws2);
+
+                        // Connect to the first server again.
+                        awaitConnect((ws3: WebSocketModule) => {
+                            closeNormal(ws3);
+                            fallbackServer.close(done);
+                        });
+                    });
+                });
+            });
+        });
+
         it('respects closing the socket during a reconnection', done => {
             greet();
             resolveOn(socket, 'method')

src/wire/Socket.ts

@@ -10,11 +10,6 @@ import {
     IReconnectionPolicy,
 } from './reconnection';
 
-/**
- * Close codes that are deemed to be recoverable by the reconnection policy
- */
-export const recoverableCloseCodes = [1000, 1011];
-
 //We don't support lz4 due to time constraints right now
 export type CompressionScheme = 'none' | 'gzip';
 
@@ -27,8 +22,8 @@ export interface ISocketOptions {
     reconnectionPolicy?: IReconnectionPolicy;
     autoReconnect?: boolean;
 
-    // Websocket URL to connect to, defaults to <TODO>
-    url?: string;
+    // Array of possible websocket URLs to connect to.
+    urls?: string[];
 
     //compression scheme, defaults to none, Will remain none until pako typings are updated
     compressionScheme?: CompressionScheme;
@@ -92,7 +87,7 @@ export enum SocketState {
 
 function getDefaults(): ISocketOptions {
     return {
-        url: '',
+        urls: [],
         replyTimeout: 10000,
         compressionScheme: 'none',
         autoReconnect: true,
@@ -119,6 +114,7 @@ export class InteractiveSocket extends EventEmitter {
     private socket: any;
     private queue: Set<Packet> = new Set<Packet>();
     private lastSequenceNumber = 0;
+    private endpointIndex = 0;
 
     constructor(options: ISocketOptions = {}) {
         super();
@@ -143,9 +139,10 @@ export class InteractiveSocket extends EventEmitter {
         });
 
         this.on('close', (evt: ICloseEvent) => {
-            // If this close event's code is not within our recoverable code array
-            // We raise it as an error and refuse to connect.
-            if (recoverableCloseCodes.indexOf(evt.code) === -1) {
+            // If this close event's code is an application error (e.g. bad authentication)
+            // or invalid status code (for Edge), we raise it as an error and refuse to
+            // reconnect.
+            if (evt.code < 1000 || evt.code > 1999 || evt.code === 1005) {
                 const err = InteractiveError.fromSocketMessage({
                     code: evt.code,
                     message: evt.reason,
@@ -213,7 +210,7 @@ export class InteractiveSocket extends EventEmitter {
             headers,
         };
 
-        const url = Url.parse(this.options.url, true);
+        const url = Url.parse(this.getURL(), true);
         // Clear out search so it populates query using the query
         // https://nodejs.org/api/url.html#url_url_format_urlobject
         url.search = null;
@@ -369,6 +366,11 @@ export class InteractiveSocket extends EventEmitter {
         this.socket.send(payload);
     }
 
+    private getURL(): string {
+        const addresses = this.options.urls;
+        return this.options.urls[this.endpointIndex++ % addresses.length];
+    }
+
     private extractMessage(packet: string | Buffer) {
         let messageString: string;
         messageString = <string>packet;