fix: prevent background worker when main app is running (#22252)

* fix: prevent background worker only when the main app is actively running

* handle ref disposals better

---------

Co-authored-by: shenlong-tanwen <139912620+shalong-tanwen@users.noreply.github.com>
Co-authored-by: Alex <alex.tran1502@gmail.com>

mise.toml

@@ -327,6 +327,7 @@ depends = [
   "mobile:pigeon:native-sync",
   "mobile:pigeon:thumbnail",
   "mobile:pigeon:background-worker",
+  "mobile:pigeon:background-worker-lock",
   "mobile:pigeon:connectivity",
 ]
 
@@ -430,6 +431,20 @@ run = [
   "dart format lib/platform/background_worker_api.g.dart",
 ]
 
+[tasks."mobile:pigeon:background-worker-lock"]
+description = "Generate background worker lock API pigeon code"
+dir = "mobile"
+hide = true
+sources = ["pigeon/background_worker_lock_api.dart"]
+outputs = [
+  "lib/platform/background_worker_lock_api.g.dart",
+  "android/app/src/main/kotlin/app/alextran/immich/background/BackgroundWorkerLock.g.kt",
+]
+run = [
+  "dart run pigeon --input pigeon/background_worker_lock_api.dart",
+  "dart format lib/platform/background_worker_lock_api.g.dart",
+]
+
 [tasks."mobile:pigeon:connectivity"]
 description = "Generate connectivity API pigeon code"
 dir = "mobile"

mobile/android/app/src/main/kotlin/app/alextran/immich/MainActivity.kt

@@ -6,6 +6,7 @@ import android.os.ext.SdkExtensions
 import app.alextran.immich.background.BackgroundEngineLock
 import app.alextran.immich.background.BackgroundWorkerApiImpl
 import app.alextran.immich.background.BackgroundWorkerFgHostApi
+import app.alextran.immich.background.BackgroundWorkerLockApi
 import app.alextran.immich.connectivity.ConnectivityApi
 import app.alextran.immich.connectivity.ConnectivityApiImpl
 import app.alextran.immich.images.ThumbnailApi
@@ -24,11 +25,9 @@ class MainActivity : FlutterFragmentActivity() {
 
   companion object {
     fun registerPlugins(ctx: Context, flutterEngine: FlutterEngine) {
-      flutterEngine.plugins.add(BackgroundServicePlugin())
-      flutterEngine.plugins.add(HttpSSLOptionsPlugin())
-      flutterEngine.plugins.add(BackgroundEngineLock())
-
       val messenger = flutterEngine.dartExecutor.binaryMessenger
+      val backgroundEngineLockImpl = BackgroundEngineLock(ctx)
+      BackgroundWorkerLockApi.setUp(messenger, backgroundEngineLockImpl)
       val nativeSyncApiImpl =
         if (Build.VERSION.SDK_INT < Build.VERSION_CODES.R || SdkExtensions.getExtensionVersion(Build.VERSION_CODES.R) < 1) {
           NativeSyncApiImpl26(ctx)
@@ -39,6 +38,10 @@ class MainActivity : FlutterFragmentActivity() {
       ThumbnailApi.setUp(messenger, ThumbnailsImpl(ctx))
       BackgroundWorkerFgHostApi.setUp(messenger, BackgroundWorkerApiImpl(ctx))
       ConnectivityApi.setUp(messenger, ConnectivityApiImpl(ctx))
+
+      flutterEngine.plugins.add(BackgroundServicePlugin())
+      flutterEngine.plugins.add(HttpSSLOptionsPlugin())
+      flutterEngine.plugins.add(backgroundEngineLockImpl)
     }
   }
 }

mobile/android/app/src/main/kotlin/app/alextran/immich/background/BackgroundEngineLock.kt

@@ -1,33 +1,50 @@
 package app.alextran.immich.background
 
+import android.content.Context
 import android.util.Log
-import androidx.work.WorkManager
-import io.flutter.embedding.engine.FlutterEngineCache
 import io.flutter.embedding.engine.plugins.FlutterPlugin
 import java.util.concurrent.atomic.AtomicInteger
 
 private const val TAG = "BackgroundEngineLock"
 
-class BackgroundEngineLock : FlutterPlugin {
+class BackgroundEngineLock(context: Context) : BackgroundWorkerLockApi, FlutterPlugin {
-  companion object {
+    private val ctx: Context = context.applicationContext
-    const val ENGINE_CACHE_KEY = "immich::background_worker::engine"
-    var engineCount = AtomicInteger(0)
-  }
 
-  override fun onAttachedToEngine(binding: FlutterPlugin.FlutterPluginBinding) {
+    companion object {
-    // work manager task is running while the main app is opened, cancel the worker
+
-    if (engineCount.incrementAndGet() > 1 && FlutterEngineCache.getInstance()
+        private var engineCount = AtomicInteger(0)
-        .get(ENGINE_CACHE_KEY) != null
+
-    ) {
+        private fun checkAndEnforceBackgroundLock(ctx: Context) {
-      WorkManager.getInstance(binding.applicationContext)
+            // work manager task is running while the main app is opened, cancel the worker
-        .cancelUniqueWork(BackgroundWorkerApiImpl.BACKGROUND_WORKER_NAME)
+            if (BackgroundWorkerPreferences(ctx).isLocked() &&
-      FlutterEngineCache.getInstance().remove(ENGINE_CACHE_KEY)
+                engineCount.get() > 1 &&
+                BackgroundWorkerApiImpl.isBackgroundWorkerRunning()
+            ) {
+                Log.i(TAG, "Background worker is locked, cancelling the background worker")
+                BackgroundWorkerApiImpl.cancelBackgroundWorker(ctx)
+            }
+        }
     }
-    Log.i(TAG, "Flutter engine attached. Attached Engines count: $engineCount")
-  }
 
-  override fun onDetachedFromEngine(binding: FlutterPlugin.FlutterPluginBinding) {
+    override fun lock() {
-    engineCount.decrementAndGet()
+        BackgroundWorkerPreferences(ctx).setLocked(true)
-    Log.i(TAG, "Flutter engine detached. Attached Engines count: $engineCount")
+        checkAndEnforceBackgroundLock(ctx)
-  }
+        Log.i(TAG, "Background worker is locked")
+    }
+
+    override fun unlock() {
+        BackgroundWorkerPreferences(ctx).setLocked(false)
+        Log.i(TAG, "Background worker is unlocked")
+    }
+
+    override fun onAttachedToEngine(binding: FlutterPlugin.FlutterPluginBinding) {
+        checkAndEnforceBackgroundLock(binding.applicationContext)
+        engineCount.incrementAndGet()
+        Log.i(TAG, "Flutter engine attached. Attached Engines count: $engineCount")
+    }
+
+    override fun onDetachedFromEngine(binding: FlutterPlugin.FlutterPluginBinding) {
+        engineCount.decrementAndGet()
+        Log.i(TAG, "Flutter engine detached. Attached Engines count: $engineCount")
+    }
 }

mobile/android/app/src/main/kotlin/app/alextran/immich/background/BackgroundWorker.kt

@@ -76,9 +76,7 @@ class BackgroundWorker(context: Context, params: WorkerParameters) :
 
     loader.ensureInitializationCompleteAsync(ctx, null, Handler(Looper.getMainLooper())) {
       engine = FlutterEngine(ctx)
-      FlutterEngineCache.getInstance().remove(BackgroundEngineLock.ENGINE_CACHE_KEY);
+      FlutterEngineCache.getInstance().put(BackgroundWorkerApiImpl.ENGINE_CACHE_KEY, engine!!)
-      FlutterEngineCache.getInstance()
-        .put(BackgroundEngineLock.ENGINE_CACHE_KEY, engine!!)
 
       // Register custom plugins
       MainActivity.registerPlugins(ctx, engine!!)
@@ -192,9 +190,9 @@ class BackgroundWorker(context: Context, params: WorkerParameters) :
     isComplete = true
     engine?.destroy()
     engine = null
-    FlutterEngineCache.getInstance().remove(BackgroundEngineLock.ENGINE_CACHE_KEY);
     flutterApi = null
     notificationManager.cancel(NOTIFICATION_ID)
+    FlutterEngineCache.getInstance().remove(BackgroundWorkerApiImpl.ENGINE_CACHE_KEY)
     waitForForegroundPromotion()
     completionHandler.set(success)
   }

mobile/android/app/src/main/kotlin/app/alextran/immich/background/BackgroundWorkerApiImpl.kt

@@ -1,7 +1,6 @@
 package app.alextran.immich.background
 
 import android.content.Context
-import android.content.SharedPreferences
 import android.provider.MediaStore
 import android.util.Log
 import androidx.work.BackoffPolicy
@@ -9,6 +8,7 @@ import androidx.work.Constraints
 import androidx.work.ExistingWorkPolicy
 import androidx.work.OneTimeWorkRequest
 import androidx.work.WorkManager
+import io.flutter.embedding.engine.FlutterEngineCache
 import java.util.concurrent.TimeUnit
 
 private const val TAG = "BackgroundWorkerApiImpl"
@@ -34,8 +34,10 @@ class BackgroundWorkerApiImpl(context: Context) : BackgroundWorkerFgHostApi {
   }
 
   companion object {
-    const val BACKGROUND_WORKER_NAME = "immich/BackgroundWorkerV1"
+    private const val BACKGROUND_WORKER_NAME = "immich/BackgroundWorkerV1"
     private const val OBSERVER_WORKER_NAME = "immich/MediaObserverV1"
+    const val ENGINE_CACHE_KEY = "immich::background_worker::engine"
+
 
     fun enqueueMediaObserver(ctx: Context) {
       val settings = BackgroundWorkerPreferences(ctx).getSettings()
@@ -73,35 +75,18 @@ class BackgroundWorkerApiImpl(context: Context) : BackgroundWorkerFgHostApi {
 
       Log.i(TAG, "Enqueued background worker with name: $BACKGROUND_WORKER_NAME")
     }
-  }
-}
 
-private class BackgroundWorkerPreferences(private val ctx: Context) {
+    fun isBackgroundWorkerRunning(): Boolean {
-  companion object {
+      // Easier to check if the engine is cached as we always cache the engine when starting the worker
-    private const val SHARED_PREF_NAME = "Immich::BackgroundWorker"
+      // and remove it when the worker is finished
-    private const val SHARED_PREF_MIN_DELAY_KEY = "BackgroundWorker::minDelaySeconds"
+      return FlutterEngineCache.getInstance().get(ENGINE_CACHE_KEY) != null
-    private const val SHARED_PREF_REQUIRE_CHARGING_KEY = "BackgroundWorker::requireCharging"
+    }
 
-    private const val DEFAULT_MIN_DELAY_SECONDS = 30L
+    fun cancelBackgroundWorker(ctx: Context) {
-    private const val DEFAULT_REQUIRE_CHARGING = false
+      WorkManager.getInstance(ctx).cancelUniqueWork(BACKGROUND_WORKER_NAME)
-  }
+      FlutterEngineCache.getInstance().remove(ENGINE_CACHE_KEY)
 
-  private val sp: SharedPreferences by lazy {
+      Log.i(TAG, "Cancelled background upload task")
-    ctx.getSharedPreferences(SHARED_PREF_NAME, Context.MODE_PRIVATE)
-  }
-
-  fun updateSettings(settings: BackgroundWorkerSettings) {
-    sp.edit().apply {
-      putLong(SHARED_PREF_MIN_DELAY_KEY, settings.minimumDelaySeconds)
-      putBoolean(SHARED_PREF_REQUIRE_CHARGING_KEY, settings.requiresCharging)
-      apply()
     }
   }
-
-  fun getSettings(): BackgroundWorkerSettings {
-    return BackgroundWorkerSettings(
-      minimumDelaySeconds = sp.getLong(SHARED_PREF_MIN_DELAY_KEY, DEFAULT_MIN_DELAY_SECONDS),
-      requiresCharging = sp.getBoolean(SHARED_PREF_REQUIRE_CHARGING_KEY, DEFAULT_REQUIRE_CHARGING),
-    )
-  }
 }

mobile/android/app/src/main/kotlin/app/alextran/immich/background/BackgroundWorkerLock.g.kt

@@ -0,0 +1,95 @@
+// Autogenerated from Pigeon (v26.0.0), do not edit directly.
+// See also: https://pub.dev/packages/pigeon
+@file:Suppress("UNCHECKED_CAST", "ArrayInDataClass")
+
+package app.alextran.immich.background
+
+import android.util.Log
+import io.flutter.plugin.common.BasicMessageChannel
+import io.flutter.plugin.common.BinaryMessenger
+import io.flutter.plugin.common.EventChannel
+import io.flutter.plugin.common.MessageCodec
+import io.flutter.plugin.common.StandardMethodCodec
+import io.flutter.plugin.common.StandardMessageCodec
+import java.io.ByteArrayOutputStream
+import java.nio.ByteBuffer
+private object BackgroundWorkerLockPigeonUtils {
+
+  fun wrapResult(result: Any?): List<Any?> {
+    return listOf(result)
+  }
+
+  fun wrapError(exception: Throwable): List<Any?> {
+    return if (exception is FlutterError) {
+      listOf(
+        exception.code,
+        exception.message,
+        exception.details
+      )
+    } else {
+      listOf(
+        exception.javaClass.simpleName,
+        exception.toString(),
+        "Cause: " + exception.cause + ", Stacktrace: " + Log.getStackTraceString(exception)
+      )
+    }
+  }
+}
+private open class BackgroundWorkerLockPigeonCodec : StandardMessageCodec() {
+  override fun readValueOfType(type: Byte, buffer: ByteBuffer): Any? {
+    return     super.readValueOfType(type, buffer)
+  }
+  override fun writeValue(stream: ByteArrayOutputStream, value: Any?)   {
+    super.writeValue(stream, value)
+  }
+}
+
+/** Generated interface from Pigeon that represents a handler of messages from Flutter. */
+interface BackgroundWorkerLockApi {
+  fun lock()
+  fun unlock()
+
+  companion object {
+    /** The codec used by BackgroundWorkerLockApi. */
+    val codec: MessageCodec<Any?> by lazy {
+      BackgroundWorkerLockPigeonCodec()
+    }
+    /** Sets up an instance of `BackgroundWorkerLockApi` to handle messages through the `binaryMessenger`. */
+    @JvmOverloads
+    fun setUp(binaryMessenger: BinaryMessenger, api: BackgroundWorkerLockApi?, messageChannelSuffix: String = "") {
+      val separatedMessageChannelSuffix = if (messageChannelSuffix.isNotEmpty()) ".$messageChannelSuffix" else ""
+      run {
+        val channel = BasicMessageChannel<Any?>(binaryMessenger, "dev.flutter.pigeon.immich_mobile.BackgroundWorkerLockApi.lock$separatedMessageChannelSuffix", codec)
+        if (api != null) {
+          channel.setMessageHandler { _, reply ->
+            val wrapped: List<Any?> = try {
+              api.lock()
+              listOf(null)
+            } catch (exception: Throwable) {
+              BackgroundWorkerLockPigeonUtils.wrapError(exception)
+            }
+            reply.reply(wrapped)
+          }
+        } else {
+          channel.setMessageHandler(null)
+        }
+      }
+      run {
+        val channel = BasicMessageChannel<Any?>(binaryMessenger, "dev.flutter.pigeon.immich_mobile.BackgroundWorkerLockApi.unlock$separatedMessageChannelSuffix", codec)
+        if (api != null) {
+          channel.setMessageHandler { _, reply ->
+            val wrapped: List<Any?> = try {
+              api.unlock()
+              listOf(null)
+            } catch (exception: Throwable) {
+              BackgroundWorkerLockPigeonUtils.wrapError(exception)
+            }
+            reply.reply(wrapped)
+          }
+        } else {
+          channel.setMessageHandler(null)
+        }
+      }
+    }
+  }
+}

mobile/android/app/src/main/kotlin/app/alextran/immich/background/BackgroundWorkerPreferences.kt

@@ -0,0 +1,49 @@
+package app.alextran.immich.background
+
+import android.content.Context
+import android.content.SharedPreferences
+import androidx.core.content.edit
+
+class BackgroundWorkerPreferences(private val ctx: Context) {
+    companion object {
+        const val SHARED_PREF_NAME = "Immich::BackgroundWorker"
+        private const val SHARED_PREF_MIN_DELAY_KEY = "BackgroundWorker::minDelaySeconds"
+        private const val SHARED_PREF_REQUIRE_CHARGING_KEY = "BackgroundWorker::requireCharging"
+        private const val SHARED_PREF_LOCK_KEY = "BackgroundWorker::isLocked"
+
+        private const val DEFAULT_MIN_DELAY_SECONDS = 30L
+        private const val DEFAULT_REQUIRE_CHARGING = false
+    }
+
+    private val sp: SharedPreferences by lazy {
+        ctx.getSharedPreferences(SHARED_PREF_NAME, Context.MODE_PRIVATE)
+    }
+
+    fun updateSettings(settings: BackgroundWorkerSettings) {
+        sp.edit {
+            putLong(SHARED_PREF_MIN_DELAY_KEY, settings.minimumDelaySeconds)
+            putBoolean(SHARED_PREF_REQUIRE_CHARGING_KEY, settings.requiresCharging)
+        }
+    }
+
+    fun getSettings(): BackgroundWorkerSettings {
+        return BackgroundWorkerSettings(
+            minimumDelaySeconds = sp.getLong(SHARED_PREF_MIN_DELAY_KEY, DEFAULT_MIN_DELAY_SECONDS),
+            requiresCharging = sp.getBoolean(
+                SHARED_PREF_REQUIRE_CHARGING_KEY,
+                DEFAULT_REQUIRE_CHARGING
+            ),
+        )
+    }
+
+    fun setLocked(paused: Boolean) {
+        sp.edit {
+            putBoolean(SHARED_PREF_LOCK_KEY, paused)
+        }
+    }
+
+    fun isLocked(): Boolean {
+        return sp.getBoolean(SHARED_PREF_LOCK_KEY, true)
+    }
+}
+

mobile/lib/domain/services/background_worker.service.dart

@@ -10,11 +10,13 @@ import 'package:immich_mobile/constants/constants.dart';
 import 'package:immich_mobile/domain/services/log.service.dart';
 import 'package:immich_mobile/entities/store.entity.dart';
 import 'package:immich_mobile/extensions/network_capability_extensions.dart';
+import 'package:immich_mobile/extensions/platform_extensions.dart';
 import 'package:immich_mobile/extensions/translate_extensions.dart';
 import 'package:immich_mobile/generated/intl_keys.g.dart';
 import 'package:immich_mobile/infrastructure/repositories/db.repository.dart';
 import 'package:immich_mobile/infrastructure/repositories/logger_db.repository.dart';
 import 'package:immich_mobile/platform/background_worker_api.g.dart';
+import 'package:immich_mobile/platform/background_worker_lock_api.g.dart';
 import 'package:immich_mobile/providers/app_settings.provider.dart';
 import 'package:immich_mobile/providers/background_sync.provider.dart';
 import 'package:immich_mobile/providers/backup/drift_backup.provider.dart';
@@ -58,7 +60,7 @@ class BackgroundWorkerFgService {
 }
 
 class BackgroundWorkerBgService extends BackgroundWorkerFlutterApi {
-  late final ProviderContainer _ref;
+  ProviderContainer? _ref;
   final Isar _isar;
   final Drift _drift;
   final DriftLogger _driftLogger;
@@ -83,29 +85,31 @@ class BackgroundWorkerBgService extends BackgroundWorkerFlutterApi {
     BackgroundWorkerFlutterApi.setUp(this);
   }
 
-  bool get _isBackupEnabled => _ref.read(appSettingsServiceProvider).getSetting(AppSettingsEnum.enableBackup);
+  bool get _isBackupEnabled => _ref?.read(appSettingsServiceProvider).getSetting(AppSettingsEnum.enableBackup) ?? false;
 
   Future<void> init() async {
     try {
       HttpSSLOptions.apply(applyNative: false);
 
-      await Future.wait([
+      await Future.wait(
-        loadTranslations(),
+        [
-        workerManager.init(dynamicSpawning: true),
+          loadTranslations(),
-        _ref.read(authServiceProvider).setOpenApiServiceEndpoint(),
+          workerManager.init(dynamicSpawning: true),
-        // Initialize the file downloader
+          _ref?.read(authServiceProvider).setOpenApiServiceEndpoint(),
-        FileDownloader().configure(
+          // Initialize the file downloader
-          globalConfig: [
+          FileDownloader().configure(
-            // maxConcurrent: 6, maxConcurrentByHost(server):6, maxConcurrentByGroup: 3
+            globalConfig: [
-            (Config.holdingQueue, (6, 6, 3)),
+              // maxConcurrent: 6, maxConcurrentByHost(server):6, maxConcurrentByGroup: 3
-            // On Android, if files are larger than 256MB, run in foreground service
+              (Config.holdingQueue, (6, 6, 3)),
-            (Config.runInForegroundIfFileLargerThan, 256),
+              // On Android, if files are larger than 256MB, run in foreground service
-          ],
+              (Config.runInForegroundIfFileLargerThan, 256),
-        ),
+            ],
-        FileDownloader().trackTasksInGroup(kDownloadGroupLivePhoto, markDownloadedComplete: false),
+          ),
-        FileDownloader().trackTasks(),
+          FileDownloader().trackTasksInGroup(kDownloadGroupLivePhoto, markDownloadedComplete: false),
-        _ref.read(fileMediaRepositoryProvider).enableBackgroundAccess(),
+          FileDownloader().trackTasks(),
-      ]);
+          _ref?.read(fileMediaRepositoryProvider).enableBackgroundAccess(),
+        ].nonNulls,
+      );
 
       configureFileDownloaderNotifications();
 
@@ -178,15 +182,17 @@ class BackgroundWorkerBgService extends BackgroundWorkerFlutterApi {
   }
 
   Future<void> _cleanup() async {
-    if (_isCleanedUp) {
+    // If ref is null, it means the service was never initialized properly
+    if (_isCleanedUp || _ref == null) {
       return;
     }
 
     try {
-      final backgroundSyncManager = _ref.read(backgroundSyncProvider);
-      final nativeSyncApi = _ref.read(nativeSyncApiProvider);
       _isCleanedUp = true;
-      _ref.dispose();
+      final backgroundSyncManager = _ref?.read(backgroundSyncProvider);
+      final nativeSyncApi = _ref?.read(nativeSyncApiProvider);
+      _ref?.dispose();
+      _ref = null;
 
       _cancellationToken.cancel();
       _logger.info("Cleaning up background worker");
@@ -199,14 +205,14 @@ class BackgroundWorkerBgService extends BackgroundWorkerFlutterApi {
         Store.dispose(),
         _drift.close(),
         _driftLogger.close(),
-        backgroundSyncManager.cancel(),
+        backgroundSyncManager?.cancel(),
-        nativeSyncApi.cancelHashing(),
+        nativeSyncApi?.cancelHashing(),
       ];
 
       if (_isar.isOpen) {
         cleanupFutures.add(_isar.close());
       }
-      await Future.wait(cleanupFutures);
+      await Future.wait(cleanupFutures.nonNulls);
       _logger.info("Background worker resources cleaned up");
     } catch (error, stack) {
       dPrint(() => 'Failed to cleanup background worker: $error with stack: $stack');
@@ -216,14 +222,18 @@ class BackgroundWorkerBgService extends BackgroundWorkerFlutterApi {
   Future<void> _handleBackup() async {
     await runZonedGuarded(
       () async {
-        if (!_isBackupEnabled || _isCleanedUp) {
+        if (_isCleanedUp) {
+          return;
+        }
+
+        if (!_isBackupEnabled) {
           _logger.info("[_handleBackup 1] Backup is disabled. Skipping backup routine");
           return;
         }
 
         _logger.info("[_handleBackup 2] Enqueuing assets for backup from the background service");
 
-        final currentUser = _ref.read(currentUserProvider);
+        final currentUser = _ref?.read(currentUserProvider);
         if (currentUser == null) {
           _logger.warning("[_handleBackup 3] No current user found. Skipping backup from background");
           return;
@@ -231,19 +241,18 @@ class BackgroundWorkerBgService extends BackgroundWorkerFlutterApi {
 
         _logger.info("[_handleBackup 4] Resume backup from background");
         if (Platform.isIOS) {
-          return _ref.read(driftBackupProvider.notifier).handleBackupResume(currentUser.id);
+          return _ref?.read(driftBackupProvider.notifier).handleBackupResume(currentUser.id);
         }
 
-        final canPing = await _ref.read(serverInfoServiceProvider).ping();
+        final canPing = await _ref?.read(serverInfoServiceProvider).ping() ?? false;
         if (!canPing) {
           _logger.warning("[_handleBackup 5] Server is not reachable. Skipping backup from background");
           return;
         }
 
-        final networkCapabilities = await _ref.read(connectivityApiProvider).getCapabilities();
+        final networkCapabilities = await _ref?.read(connectivityApiProvider).getCapabilities() ?? [];
-
         return _ref
-            .read(uploadServiceProvider)
+            ?.read(uploadServiceProvider)
             .startBackupWithHttpClient(currentUser.id, networkCapabilities.hasWifi, _cancellationToken);
       },
       (error, stack) {
@@ -253,18 +262,18 @@ class BackgroundWorkerBgService extends BackgroundWorkerFlutterApi {
   }
 
   Future<void> _syncAssets({Duration? hashTimeout}) async {
-    await _ref.read(backgroundSyncProvider).syncLocal();
+    await _ref?.read(backgroundSyncProvider).syncLocal();
     if (_isCleanedUp) {
       return;
     }
 
-    await _ref.read(backgroundSyncProvider).syncRemote();
+    await _ref?.read(backgroundSyncProvider).syncRemote();
     if (_isCleanedUp) {
       return;
     }
 
-    var hashFuture = _ref.read(backgroundSyncProvider).hashAssets();
+    var hashFuture = _ref?.read(backgroundSyncProvider).hashAssets();
-    if (hashTimeout != null) {
+    if (hashTimeout != null && hashFuture != null) {
       hashFuture = hashFuture.timeout(
         hashTimeout,
         onTimeout: () {
@@ -277,6 +286,23 @@ class BackgroundWorkerBgService extends BackgroundWorkerFlutterApi {
   }
 }
 
+class BackgroundWorkerLockService {
+  final BackgroundWorkerLockApi _hostApi;
+  const BackgroundWorkerLockService(this._hostApi);
+
+  Future<void> lock() async {
+    if (CurrentPlatform.isAndroid) {
+      return _hostApi.lock();
+    }
+  }
+
+  Future<void> unlock() async {
+    if (CurrentPlatform.isAndroid) {
+      return _hostApi.unlock();
+    }
+  }
+}
+
 /// Native entry invoked from the background worker. If renaming or moving this to a different
 /// library, make sure to update the entry points and URI in native workers as well
 @pragma('vm:entry-point')

mobile/lib/main.dart

@@ -12,9 +12,11 @@ import 'package:flutter_displaymode/flutter_displaymode.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:immich_mobile/constants/constants.dart';
 import 'package:immich_mobile/constants/locales.dart';
+import 'package:immich_mobile/domain/services/background_worker.service.dart';
 import 'package:immich_mobile/entities/store.entity.dart';
 import 'package:immich_mobile/extensions/build_context_extensions.dart';
 import 'package:immich_mobile/generated/codegen_loader.g.dart';
+import 'package:immich_mobile/platform/background_worker_lock_api.g.dart';
 import 'package:immich_mobile/providers/app_life_cycle.provider.dart';
 import 'package:immich_mobile/providers/asset_viewer/share_intent_upload.provider.dart';
 import 'package:immich_mobile/providers/db.provider.dart';
@@ -32,6 +34,7 @@ import 'package:immich_mobile/theme/dynamic_theme.dart';
 import 'package:immich_mobile/theme/theme_data.dart';
 import 'package:immich_mobile/utils/bootstrap.dart';
 import 'package:immich_mobile/utils/cache/widgets_binding.dart';
+import 'package:immich_mobile/utils/debug_print.dart';
 import 'package:immich_mobile/utils/http_ssl_options.dart';
 import 'package:immich_mobile/utils/licenses.dart';
 import 'package:immich_mobile/utils/migration.dart';
@@ -39,10 +42,10 @@ import 'package:intl/date_symbol_data_local.dart';
 import 'package:logging/logging.dart';
 import 'package:timezone/data/latest.dart';
 import 'package:worker_manager/worker_manager.dart';
-import 'package:immich_mobile/utils/debug_print.dart';
 
 void main() async {
   ImmichWidgetsBinding();
+  unawaited(BackgroundWorkerLockService(BackgroundWorkerLockApi()).lock());
   final (isar, drift, logDb) = await Bootstrap.initDB();
   await Bootstrap.initDomain(isar, drift, logDb);
   await initApp();

mobile/lib/pages/common/splash_screen.page.dart

@@ -1,3 +1,5 @@
+import 'dart:async';
+
 import 'package:auto_route/auto_route.dart';
 import 'package:flutter/material.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';

mobile/lib/platform/background_worker_lock_api.g.dart

@@ -0,0 +1,97 @@
+// Autogenerated from Pigeon (v26.0.0), do not edit directly.
+// See also: https://pub.dev/packages/pigeon
+// ignore_for_file: public_member_api_docs, non_constant_identifier_names, avoid_as, unused_import, unnecessary_parenthesis, prefer_null_aware_operators, omit_local_variable_types, unused_shown_name, unnecessary_import, no_leading_underscores_for_local_identifiers
+
+import 'dart:async';
+import 'dart:typed_data' show Float64List, Int32List, Int64List, Uint8List;
+
+import 'package:flutter/foundation.dart' show ReadBuffer, WriteBuffer;
+import 'package:flutter/services.dart';
+
+PlatformException _createConnectionError(String channelName) {
+  return PlatformException(
+    code: 'channel-error',
+    message: 'Unable to establish connection on channel: "$channelName".',
+  );
+}
+
+class _PigeonCodec extends StandardMessageCodec {
+  const _PigeonCodec();
+  @override
+  void writeValue(WriteBuffer buffer, Object? value) {
+    if (value is int) {
+      buffer.putUint8(4);
+      buffer.putInt64(value);
+    } else {
+      super.writeValue(buffer, value);
+    }
+  }
+
+  @override
+  Object? readValueOfType(int type, ReadBuffer buffer) {
+    switch (type) {
+      default:
+        return super.readValueOfType(type, buffer);
+    }
+  }
+}
+
+class BackgroundWorkerLockApi {
+  /// Constructor for [BackgroundWorkerLockApi].  The [binaryMessenger] named argument is
+  /// available for dependency injection.  If it is left null, the default
+  /// BinaryMessenger will be used which routes to the host platform.
+  BackgroundWorkerLockApi({BinaryMessenger? binaryMessenger, String messageChannelSuffix = ''})
+    : pigeonVar_binaryMessenger = binaryMessenger,
+      pigeonVar_messageChannelSuffix = messageChannelSuffix.isNotEmpty ? '.$messageChannelSuffix' : '';
+  final BinaryMessenger? pigeonVar_binaryMessenger;
+
+  static const MessageCodec<Object?> pigeonChannelCodec = _PigeonCodec();
+
+  final String pigeonVar_messageChannelSuffix;
+
+  Future<void> lock() async {
+    final String pigeonVar_channelName =
+        'dev.flutter.pigeon.immich_mobile.BackgroundWorkerLockApi.lock$pigeonVar_messageChannelSuffix';
+    final BasicMessageChannel<Object?> pigeonVar_channel = BasicMessageChannel<Object?>(
+      pigeonVar_channelName,
+      pigeonChannelCodec,
+      binaryMessenger: pigeonVar_binaryMessenger,
+    );
+    final Future<Object?> pigeonVar_sendFuture = pigeonVar_channel.send(null);
+    final List<Object?>? pigeonVar_replyList = await pigeonVar_sendFuture as List<Object?>?;
+    if (pigeonVar_replyList == null) {
+      throw _createConnectionError(pigeonVar_channelName);
+    } else if (pigeonVar_replyList.length > 1) {
+      throw PlatformException(
+        code: pigeonVar_replyList[0]! as String,
+        message: pigeonVar_replyList[1] as String?,
+        details: pigeonVar_replyList[2],
+      );
+    } else {
+      return;
+    }
+  }
+
+  Future<void> unlock() async {
+    final String pigeonVar_channelName =
+        'dev.flutter.pigeon.immich_mobile.BackgroundWorkerLockApi.unlock$pigeonVar_messageChannelSuffix';
+    final BasicMessageChannel<Object?> pigeonVar_channel = BasicMessageChannel<Object?>(
+      pigeonVar_channelName,
+      pigeonChannelCodec,
+      binaryMessenger: pigeonVar_binaryMessenger,
+    );
+    final Future<Object?> pigeonVar_sendFuture = pigeonVar_channel.send(null);
+    final List<Object?>? pigeonVar_replyList = await pigeonVar_sendFuture as List<Object?>?;
+    if (pigeonVar_replyList == null) {
+      throw _createConnectionError(pigeonVar_channelName);
+    } else if (pigeonVar_replyList.length > 1) {
+      throw PlatformException(
+        code: pigeonVar_replyList[0]! as String,
+        message: pigeonVar_replyList[1] as String?,
+        details: pigeonVar_replyList[2],
+      );
+    } else {
+      return;
+    }
+  }
+}

mobile/lib/providers/app_life_cycle.provider.dart

@@ -15,6 +15,7 @@ import 'package:immich_mobile/providers/backup/drift_backup.provider.dart';
 import 'package:immich_mobile/providers/backup/ios_background_settings.provider.dart';
 import 'package:immich_mobile/providers/backup/manual_upload.provider.dart';
 import 'package:immich_mobile/providers/gallery_permission.provider.dart';
+import 'package:immich_mobile/providers/infrastructure/platform.provider.dart';
 import 'package:immich_mobile/providers/memory.provider.dart';
 import 'package:immich_mobile/providers/notification_permission.provider.dart';
 import 'package:immich_mobile/providers/server_info.provider.dart';
@@ -138,6 +139,7 @@ class AppLifeCycleNotifier extends StateNotifier<AppLifeCycleEnum> {
 
   Future<void> _handleBetaTimelineResume() async {
     _ref.read(backupProvider.notifier).cancelBackup();
+    unawaited(_ref.read(backgroundWorkerLockServiceProvider).lock());
 
     // Give isolates time to complete any ongoing database transactions
     await Future.delayed(const Duration(milliseconds: 500));
@@ -209,6 +211,9 @@ class AppLifeCycleNotifier extends StateNotifier<AppLifeCycleEnum> {
     _pauseOperation = Completer<void>();
 
     try {
+      if (Store.isBetaTimelineEnabled) {
+        unawaited(_ref.read(backgroundWorkerLockServiceProvider).unlock());
+      }
       await _performPause();
     } catch (e, stackTrace) {
       _log.severe("Error during app pause", e, stackTrace);
@@ -240,6 +245,10 @@ class AppLifeCycleNotifier extends StateNotifier<AppLifeCycleEnum> {
   Future<void> handleAppDetached() async {
     state = AppLifeCycleEnum.detached;
 
+    if (Store.isBetaTimelineEnabled) {
+      unawaited(_ref.read(backgroundWorkerLockServiceProvider).unlock());
+    }
+
     // Flush logs before closing database
     try {
       LogService.I.flush();

mobile/lib/providers/infrastructure/platform.provider.dart

@@ -1,12 +1,17 @@
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:immich_mobile/domain/services/background_worker.service.dart';
 import 'package:immich_mobile/platform/background_worker_api.g.dart';
+import 'package:immich_mobile/platform/background_worker_lock_api.g.dart';
 import 'package:immich_mobile/platform/connectivity_api.g.dart';
 import 'package:immich_mobile/platform/native_sync_api.g.dart';
 import 'package:immich_mobile/platform/thumbnail_api.g.dart';
 
 final backgroundWorkerFgServiceProvider = Provider((_) => BackgroundWorkerFgService(BackgroundWorkerFgHostApi()));
 
+final backgroundWorkerLockServiceProvider = Provider<BackgroundWorkerLockService>(
+  (_) => BackgroundWorkerLockService(BackgroundWorkerLockApi()),
+);
+
 final nativeSyncApiProvider = Provider<NativeSyncApi>((_) => NativeSyncApi());
 
 final connectivityApiProvider = Provider<ConnectivityApi>((_) => ConnectivityApi());

mobile/makefile

@@ -9,10 +9,12 @@ pigeon:
 	dart run pigeon --input pigeon/native_sync_api.dart
 	dart run pigeon --input pigeon/thumbnail_api.dart
 	dart run pigeon --input pigeon/background_worker_api.dart
+	dart run pigeon --input pigeon/background_worker_lock_api.dart
 	dart run pigeon --input pigeon/connectivity_api.dart
 	dart format lib/platform/native_sync_api.g.dart
 	dart format lib/platform/thumbnail_api.g.dart
 	dart format lib/platform/background_worker_api.g.dart
+	dart format lib/platform/background_worker_lock_api.g.dart
 	dart format lib/platform/connectivity_api.g.dart
 
 watch:

mobile/pigeon/background_worker_lock_api.dart

@@ -0,0 +1,17 @@
+import 'package:pigeon/pigeon.dart';
+
+@ConfigurePigeon(
+  PigeonOptions(
+    dartOut: 'lib/platform/background_worker_lock_api.g.dart',
+    kotlinOut: 'android/app/src/main/kotlin/app/alextran/immich/background/BackgroundWorkerLock.g.kt',
+    kotlinOptions: KotlinOptions(package: 'app.alextran.immich.background', includeErrorClass: false),
+    dartOptions: DartOptions(),
+    dartPackageName: 'immich_mobile',
+  ),
+)
+@HostApi()
+abstract class BackgroundWorkerLockApi {
+  void lock();
+
+  void unlock();
+}