Avoid spamming server if it's closing connections right after they were opened

README.md

@@ -103,6 +103,10 @@ wsOpts = {
   awareness: new awarenessProtocol.Awareness(ydoc),
   // Specify the maximum amount to wait between reconnects (we use exponential backoff).
   maxBackoffTime: 2500
+  // Specify the maximum amount to wait between reconnects if previous connection succeeded (we use exponential backoff).
+  // This prevents connections that close right after their successful creation from being retried immediately.
+  // Backoff only resets when a connection has been open for `maxBackoffIntervalOnSuccessfulConnects * 2` ms
+  maxBackoffIntervalOnSuccessfulConnects: 2500
 }
 ```
 

src/y-websocket.js

@@ -172,6 +172,16 @@ const closeWebsocketConnection = (provider, ws, event) => {
  * @param {WebsocketProvider} provider
  */
 const setupWS = (provider) => {
+  // Start with 100ms interval between successful connects and increase with exponential backoff
+  const backoff = math.min(math.pow(2, provider.wsSubsequentConnects) * 50, provider.maxBackoffIntervalOnSuccessfulConnects)
+  const timeout = provider.wsLastConnectAt ? Date.now() - provider.wsLastConnectAt.getTime() : backoff
+  if (timeout < backoff) {
+    setTimeout(setupWS, backoff - timeout, provider)
+    return
+  } else if (timeout > provider.maxBackoffIntervalOnSuccessfulConnects * 2) {
+    provider.wsSubsequentConnects = 0
+  }
+
   if (provider.shouldConnect && provider.ws === null) {
     const websocket = new provider._WS(provider.url, provider.protocols)
     websocket.binaryType = 'arraybuffer'
@@ -194,6 +204,8 @@ const setupWS = (provider) => {
       closeWebsocketConnection(provider, websocket, event)
     }
     websocket.onopen = () => {
+      provider.wsLastConnectAt = new Date()
+      provider.wsSubsequentConnects++
       provider.wsLastMessageReceived = time.getUnixTime()
       provider.wsconnecting = false
       provider.wsconnected = true
@@ -265,6 +277,7 @@ export class WebsocketProvider extends ObservableV2 {
    * @param {typeof WebSocket} [opts.WebSocketPolyfill] Optionall provide a WebSocket polyfill
    * @param {number} [opts.resyncInterval] Request server state every `resyncInterval` milliseconds
    * @param {number} [opts.maxBackoffTime] Maximum amount of time to wait before trying to reconnect (we try to reconnect using exponential backoff)
+   * @param {number} [opts.maxBackoffIntervalOnSuccessfulConnects] Maximum amount of time to wait before trying to reconnect if previous connection succeeded (we try to reconnect using exponential backoff). Backoff only resets after a connection has been open for `maxBackoffIntervalOnSuccessfulConnects * 2` ms
    * @param {boolean} [opts.disableBc] Disable cross-tab BroadcastChannel communication
    */
   constructor (serverUrl, roomname, doc, {
@@ -275,6 +288,7 @@ export class WebsocketProvider extends ObservableV2 {
     WebSocketPolyfill = WebSocket,
     resyncInterval = -1,
     maxBackoffTime = 2500,
+    maxBackoffIntervalOnSuccessfulConnects = 2500,
     disableBc = false
   } = {}) {
     super()
@@ -285,6 +299,7 @@ export class WebsocketProvider extends ObservableV2 {
     this.serverUrl = serverUrl
     this.bcChannel = serverUrl + '/' + roomname
     this.maxBackoffTime = maxBackoffTime
+    this.maxBackoffIntervalOnSuccessfulConnects = maxBackoffIntervalOnSuccessfulConnects
     /**
      * The specified url parameters. This can be safely updated. The changed parameters will be used
      * when a new connection is established.
@@ -301,6 +316,8 @@ export class WebsocketProvider extends ObservableV2 {
     this.bcconnected = false
     this.disableBc = disableBc
     this.wsUnsuccessfulReconnects = 0
+    this.wsLastConnectAt = null
+    this.wsSubsequentConnects = 0
     this.messageHandlers = messageHandlers.slice()
     /**
      * @type {boolean}