use mutex

mobile/lib/domain/utils/background_sync.dart

@@ -9,8 +9,57 @@ class BackgroundSyncManager {
   Cancelable<void>? _deviceAlbumSyncTask;
   Cancelable<void>? _hashTask;
 
+  Completer<void>? _localSyncMutex;
+  Completer<void>? _remoteSyncMutex;
+  Completer<void>? _hashMutex;
+
   BackgroundSyncManager();
 
+  Future<T> _withMutex<T>(
+    Completer<void>? Function() getMutex,
+    void Function(Completer<void>?) setMutex,
+    Future<T> Function() operation,
+  ) async {
+    while (getMutex() != null) {
+      await getMutex()!.future;
+    }
+
+    final mutex = Completer<void>();
+    setMutex(mutex);
+
+    try {
+      final result = await operation();
+      return result;
+    } finally {
+      setMutex(null);
+      mutex.complete();
+    }
+  }
+
+  Future<T> _withLocalSyncMutex<T>(Future<T> Function() operation) {
+    return _withMutex(
+      () => _localSyncMutex,
+      (mutex) => _localSyncMutex = mutex,
+      operation,
+    );
+  }
+
+  Future<T> _withRemoteSyncMutex<T>(Future<T> Function() operation) {
+    return _withMutex(
+      () => _remoteSyncMutex,
+      (mutex) => _remoteSyncMutex = mutex,
+      operation,
+    );
+  }
+
+  Future<T> _withHashMutex<T>(Future<T> Function() operation) {
+    return _withMutex(
+      () => _hashMutex,
+      (mutex) => _hashMutex = mutex,
+      operation,
+    );
+  }
+
   Future<void> cancel() {
     final futures = <Future>[];
 
@@ -25,51 +74,57 @@ class BackgroundSyncManager {
 
   // No need to cancel the task, as it can also be run when the user logs out
   Future<void> syncLocal({bool full = false}) {
-    if (_deviceAlbumSyncTask != null) {
+    return _withLocalSyncMutex(() async {
-      return _deviceAlbumSyncTask!.future;
+      if (_deviceAlbumSyncTask != null) {
-    }
+        return _deviceAlbumSyncTask!.future;
+      }
 
-    // We use a ternary operator to avoid [_deviceAlbumSyncTask] from being
+      // We use a ternary operator to avoid [_deviceAlbumSyncTask] from being
-    // captured by the closure passed to [runInIsolateGentle].
+      // captured by the closure passed to [runInIsolateGentle].
-    _deviceAlbumSyncTask = full
+      _deviceAlbumSyncTask = full
-        ? runInIsolateGentle(
+          ? runInIsolateGentle(
-            computation: (ref) =>
+              computation: (ref) =>
-                ref.read(localSyncServiceProvider).sync(full: true),
+                  ref.read(localSyncServiceProvider).sync(full: true),
-          )
+            )
-        : runInIsolateGentle(
+          : runInIsolateGentle(
-            computation: (ref) =>
+              computation: (ref) =>
-                ref.read(localSyncServiceProvider).sync(full: false),
+                  ref.read(localSyncServiceProvider).sync(full: false),
-          );
+            );
 
-    return _deviceAlbumSyncTask!.whenComplete(() {
+      return _deviceAlbumSyncTask!.whenComplete(() {
-      _deviceAlbumSyncTask = null;
+        _deviceAlbumSyncTask = null;
+      });
     });
   }
 
 // No need to cancel the task, as it can also be run when the user logs out
   Future<void> hashAssets() {
-    if (_hashTask != null) {
+    return _withHashMutex(() async {
-      return _hashTask!.future;
+      if (_hashTask != null) {
-    }
+        return _hashTask!.future;
+      }
 
-    _hashTask = runInIsolateGentle(
+      _hashTask = runInIsolateGentle(
-      computation: (ref) => ref.read(hashServiceProvider).hashAssets(),
+        computation: (ref) => ref.read(hashServiceProvider).hashAssets(),
-    );
+      );
-    return _hashTask!.whenComplete(() {
+      return _hashTask!.whenComplete(() {
-      _hashTask = null;
+        _hashTask = null;
+      });
     });
   }
 
   Future<void> syncRemote() {
-    if (_syncTask != null) {
+    return _withRemoteSyncMutex(() async {
-      return _syncTask!.future;
+      if (_syncTask != null) {
-    }
+        return _syncTask!.future;
+      }
 
-    _syncTask = runInIsolateGentle(
+      _syncTask = runInIsolateGentle(
-      computation: (ref) => ref.read(syncStreamServiceProvider).sync(),
+        computation: (ref) => ref.read(syncStreamServiceProvider).sync(),
-    );
+      );
-    return _syncTask!.whenComplete(() {
+      return _syncTask!.whenComplete(() {
-      _syncTask = null;
+        _syncTask = null;
+      });
     });
   }
 }

mobile/lib/widgets/common/immich_sliver_app_bar.dart

@@ -73,7 +73,10 @@ class ImmichSliverAppBar extends ConsumerWidget {
             onPressed: () => context.pop(),
           ),
           IconButton(
-            onPressed: () => ref.read(backgroundSyncProvider).syncRemote(),
+            onPressed: () {
+              ref.read(backgroundSyncProvider).syncLocal(full: true);
+              ref.read(backgroundSyncProvider).syncRemote();
+            },
             icon: const Icon(
               Icons.sync,
             ),