feat(realtime): Allows for immediate reconnect

This change allows the realtime socket to try an immediate
reconnection for some events. This avoid waiting seconds or
minutes when recovering from an offline situation.

packages/cozy-realtime/src/CozyRealtime.js

@@ -98,30 +98,31 @@ class CozyRealtime {
    * Connects a new websocket as soon as possible
    * @private
    */
-  async connect() {
+  async connect({ immediate = false } = {}) {
     logger.info('connecting…')
     // avoid multiple concurrent calls to connect, keeps the first one
     if (this.waitingForConnect) {
       logger.debug('Pending reconnection, skipping reconnect')
-      return
-    }
-    logger.debug('No pending reconnection, will reconnect')
-    try {
-      this.waitingForConnect = true
-      await this.retryManager.waitBeforeNextAttempt()
-      this.createSocket()
-    } finally {
-      this.waitingForConnect = false
+      if (immediate) this.retryManager.stopCurrentAttemptWaitingTime()
+    } else {
+      logger.debug('No pending reconnection, will reconnect')
+      try {
+        this.waitingForConnect = true
+        if (!immediate) await this.retryManager.waitBeforeNextAttempt()
+        this.createSocket()
+      } finally {
+        this.waitingForConnect = false
+      }
     }
   }
 
   /**
    * Throws the previous socket and connect a new one
    * @private
    */
-  async reconnect() {
+  async reconnect({ immediate = false } = {}) {
     if (this.hasWebSocket()) this.revokeWebSocket()
-    this.connect()
+    this.connect({ immediate })
   }
 
   /**
@@ -602,7 +603,7 @@ class CozyRealtime {
    * @private
    */
   onResume() {
-    this.reconnect()
+    this.reconnect({ immediate: true })
   }
 
   /* * * * * * * * * * * * * * * */
@@ -637,7 +638,7 @@ class CozyRealtime {
    */
   onOnline() {
     logger.info('reconnect because receiving an online event')
-    this.reconnect()
+    this.reconnect({ immediate: true })
   }
 
   /**

packages/cozy-realtime/src/CozyRealtime.spec.js

@@ -657,14 +657,55 @@ describe('CozyRealtime', () => {
         realtime.retryManager.onFailure()
         realtime.retryManager.onFailure()
         realtime.retryManager.onFailure()
-        realtime.onOnline()
+        realtime.onWebSocketError()
         await sleep(25)
 
         // reconnect before the previous connection finishes to wait
         realtime.onOnline()
         await realtime.waitForSocketReady()
 
         expect(server.onconnect).toHaveBeenCalledTimes(2)
+        realtime.unsubscribeAll()
+        server.stop(done)
+      })
+    })
+
+    describe('on becoming online', () => {
+      it('reconnects', async done => {
+        const server = createSocketServer()
+        server.onconnect.named = 'reconnect'
+        const realtime = createRealtime()
+        const handler = jest.fn()
+        realtime.subscribe(event, type, undefined, handler)
+        await realtime.waitForSocketReady()
+
+        const event = new Event('online')
+        window.dispatchEvent(event)
+
+        await sleep(100)
+        await realtime.waitForSocketReady()
+        expect(server.onconnect).toHaveBeenCalledTimes(2)
+        realtime.unsubscribeAll()
+        server.stop(done)
+      })
+
+      it('reconnects immediatly', async done => {
+        const server = createSocketServer()
+        const realtime = createRealtime()
+        const handler = jest.fn()
+        realtime.subscribe(event, type, undefined, handler)
+        await realtime.waitForSocketReady()
+
+        realtime.retryManager.onFailure()
+        realtime.retryManager.onFailure()
+        realtime.retryManager.onFailure()
+        realtime.retryManager.onFailure()
+        const event = new Event('online')
+        window.dispatchEvent(event)
+
+        await sleep(100)
+        expect(server.onconnect).toHaveBeenCalledTimes(2)
+        realtime.unsubscribeAll()
         server.stop(done)
       })
     })

packages/cozy-realtime/src/RetryManager.js

@@ -161,11 +161,31 @@ class RetryManager {
   async waitBeforeNextAttempt() {
     logger.debug('waitBeforeNextAttempt', this.wait)
     if (this.wait) {
-      await new Promise(resolve => {
-        global.setTimeout(resolve, this.wait)
-      })
+      if (!this.waiting) {
+        let stop
+        const promise = new Promise(resolve => {
+          stop = () => {
+            // only remove the waiting status if it's still
+            // the current promise that is waiting and not a new one
+            if (this.waiting === promise) this.waiting = null
+            resolve()
+          }
+          global.setTimeout(stop, this.wait)
+        })
+        promise.stop = stop
+        this.waiting = promise
+      }
+      await this.waiting
     }
   }
+
+  /**
+   * If an attempt is waiting, stop the wait and retry now
+   * @see waitBeforeNextAttempt()
+   */
+  stopCurrentAttemptWaitingTime() {
+    if (this.waiting) this.waiting.stop()
+  }
 }
 
 MicroEE.mixin(RetryManager)

packages/cozy-realtime/src/RetryManager.spec.js

@@ -149,4 +149,22 @@ describe('RetryManager', () => {
       expect(retry.shouldEmitError()).toBeFalsy()
     })
   })
+
+  describe('stopCurrentAttemptWaitingTime', () => {
+    it('stop the waiting time', async () => {
+      const handler = jest.fn()
+      const retry = new RetryManager()
+      retry.onFailure()
+      retry.onFailure()
+      retry.onFailure()
+      retry.onFailure()
+      retry.onFailure()
+      retry.onFailure()
+      retry.onFailure()
+      retry.waitBeforeNextAttempt().then(handler)
+      retry.stopCurrentAttemptWaitingTime()
+      await sleep(25)
+      expect(handler).toHaveBeenCalled()
+    })
+  })
 })