Cleanup the background task that pauses the SDK when resigning active (#903)

* checking if the stop taskHandle is finished before stopping the bg task

* stopping the sync in background now works properly

* this will prevent the case in which if the app suspends and then is immediately foregrounded again, we do not start the sync

* now works as intended

* code improvement

* improved the code a bit

ElementX/Sources/Application/AppCoordinator.swift

@@ -348,7 +348,7 @@ class AppCoordinator: AppCoordinatorProtocol, AuthenticationCoordinatorDelegate,
             hideLoadingIndicator()
         }
         
-        userSession.clientProxy.stopSync()
+        stopSync()
         userSessionFlowCoordinator?.stop()
         
         guard !isSoft else {
@@ -462,7 +462,7 @@ class AppCoordinator: AppCoordinatorProtocol, AuthenticationCoordinatorDelegate,
         
         navigationRootCoordinator.setRootCoordinator(SplashScreenCoordinator())
         
-        userSession.clientProxy.stopSync()
+        stopSync()
         userSessionFlowCoordinator?.stop()
         
         let userID = userSession.userID
@@ -536,20 +536,24 @@ class AppCoordinator: AppCoordinatorProtocol, AuthenticationCoordinatorDelegate,
     @objc
     private func applicationWillResignActive() {
         MXLog.info("Application will resign active")
-        
+
         guard backgroundTask == nil else {
             return
         }
 
         backgroundTask = backgroundTaskService.startBackgroundTask(withName: "SuspendApp: \(UUID().uuidString)") { [weak self] in
-            guard let self else { return }
-            
-            stopSync()
-        
-            backgroundTask = nil
-            isSuspended = true
+            guard let self else {
+                return
+            }
+            userSession?.clientProxy.stopSync {
+                // No need to weakify self, this is a non escaping closure
+                self.backgroundTask?.stop()
+                self.backgroundTask = nil
+            }
         }
-        
+
+        isSuspended = true
+
         // This does seem to work if scheduled from the background task above
         // Schedule it here instead but with an earliest being date of 30 seconds
         scheduleBackgroundAppRefresh()
@@ -562,10 +566,11 @@ class AppCoordinator: AppCoordinatorProtocol, AuthenticationCoordinatorDelegate,
         backgroundTask?.stop()
         backgroundTask = nil
 
-        if isSuspended {
-            isSuspended = false
+        if isSuspended, userSession?.clientProxy.isSyncing == false {
             startSync()
         }
+
+        isSuspended = false
     }
     
     // MARK: Background app refresh

ElementX/Sources/Services/Client/ClientProxy.swift

@@ -152,16 +152,30 @@ class ClientProxy: ClientProxyProtocol {
             return nil
         }
     }
+
+    var isSyncing: Bool {
+        slidingSyncObserverToken != nil
+    }
     
     func startSync() {
         MXLog.info("Starting sync")
-        guard slidingSyncObserverToken == nil else {
+        guard !isSyncing else {
             return
         }
         
         slidingSyncObserverToken = slidingSync?.sync()
     }
-    
+
+    func stopSync(completionHandler: () -> Void) {
+        guard let slidingSyncObserverToken else {
+            MXLog.info("No sync is present")
+            return
+        }
+        stopSync()
+        while !slidingSyncObserverToken.isFinished() { }
+        completionHandler()
+    }
+
     func stopSync() {
         MXLog.info("Stopping sync")
         slidingSyncObserverToken?.cancel()
@@ -178,7 +192,7 @@ class ClientProxy: ClientProxyProtocol {
             }
         }
     }
-    
+
     func createDirectRoom(with userID: String) async -> Result<String, ClientProxyError> {
         await Task.dispatch(on: clientQueue) {
             do {

ElementX/Sources/Services/Client/ClientProxyProtocol.swift

@@ -81,9 +81,15 @@ protocol ClientProxyProtocol: AnyObject, MediaLoaderProtocol {
     var allRoomsSummaryProvider: RoomSummaryProviderProtocol? { get }
     
     var invitesSummaryProvider: RoomSummaryProviderProtocol? { get }
+
+    var isSyncing: Bool { get }
     
     func startSync()
-    
+
+    /// Stops the sync usiung non escaping closure.
+    /// It's supposed to be used for the expiration handlers to guarantee its synchronous execution
+    func stopSync(completionHandler: () -> Void)
+
     func stopSync()
     
     func directRoomForUserID(_ userID: String) async -> Result<String?, ClientProxyError>

ElementX/Sources/Services/Client/MockClientProxy.swift

@@ -33,6 +33,8 @@ class MockClientProxy: ClientProxyProtocol {
     var invitesSummaryProvider: RoomSummaryProviderProtocol? = MockRoomSummaryProvider()
 
     var avatarURLPublisher: AnyPublisher<URL?, Never> { Empty().eraseToAnyPublisher() }
+
+    var isSyncing: Bool { false }
     
     internal init(userID: String, roomSummaryProvider: RoomSummaryProviderProtocol? = MockRoomSummaryProvider()) {
         self.userID = userID
@@ -43,6 +45,8 @@ class MockClientProxy: ClientProxyProtocol {
     
     func startSync() { }
     
+    func stopSync(completionHandler: () -> Void) { }
+
     func stopSync() { }
     
     func directRoomForUserID(_ userID: String) async -> Result<String?, ClientProxyError> {

changelog.d/438.bugfix

@@ -0,0 +1 @@
+Stopping bg task when the app is suspended and the slidingSyncObserver is finished.