Throttle calls to update remote touch token

app/lib/entity/file/data_source.dart

@@ -17,6 +17,7 @@ import 'package:nc_photos/exception.dart';
 import 'package:nc_photos/iterable_extension.dart';
 import 'package:nc_photos/object_extension.dart';
 import 'package:nc_photos/or_null.dart';
+import 'package:nc_photos/throttler.dart';
 import 'package:nc_photos/touch_token_manager.dart';
 import 'package:nc_photos/use_case/compat/v32.dart';
 import 'package:path/path.dart' as path_lib;
@@ -539,13 +540,18 @@ class FileCachedDataSource implements FileDataSource {
 
     // generate a new random token
     final token = const Uuid().v4().replaceAll("-", "");
-    const tokenManager = TouchTokenManager();
     final dir = File(path: path_lib.dirname(f.path));
-    await tokenManager.setLocalToken(account, dir, token);
-    final fileRepo = FileRepo(this);
-    await tokenManager.setRemoteToken(fileRepo, account, dir, token);
-    _log.info(
-        "[updateMetadata] New touch token '$token' for dir '${dir.path}'");
+    await const TouchTokenManager().setLocalToken(account, dir, token);
+    // don't update remote token that frequently
+    (_touchTokenThrottlers["${account.url}/${dir.path}"] ??= Throttler(
+      onTriggered: _updateRemoteTouchToken,
+      logTag: "FileCachedDataSource._touchTokenThrottlers",
+    ))
+        .trigger(
+      maxResponceTime: const Duration(seconds: 20),
+      maxPendingCount: 20,
+      data: _TouchTokenThrottlerData(account, dir, token),
+    );
   }
 
   @override
@@ -575,6 +581,25 @@ class FileCachedDataSource implements FileDataSource {
     await _remoteSrc.createDir(account, path);
   }
 
+  Future<void> updateRemoteTouchTokenNow() async {
+    for (final t in _touchTokenThrottlers.values) {
+      await t.triggerNow();
+    }
+  }
+
+  Future<void> _updateRemoteTouchToken(
+      List<_TouchTokenThrottlerData> data) async {
+    try {
+      final fileRepo = FileRepo(this);
+      final d = data.last;
+      await const TouchTokenManager()
+          .setRemoteToken(fileRepo, d.account, d.dir, d.token);
+    } catch (e, stackTrace) {
+      _log.shout("[_updateRemoteTouchToken] Failed while setRemoteToken", e,
+          stackTrace);
+    }
+  }
+
   final DiContainer _c;
   final bool shouldCheckCache;
   final FileForwardCacheManager? forwardCacheManager;
@@ -582,9 +607,19 @@ class FileCachedDataSource implements FileDataSource {
   final _remoteSrc = const FileWebdavDataSource();
   final FileSqliteDbDataSource _sqliteDbSrc;
 
+  final _touchTokenThrottlers = <String, Throttler<_TouchTokenThrottlerData>>{};
+
   static final _log = Logger("entity.file.data_source.FileCachedDataSource");
 }
 
+class _TouchTokenThrottlerData {
+  const _TouchTokenThrottlerData(this.account, this.dir, this.token);
+
+  final Account account;
+  final File dir;
+  final String token;
+}
+
 /// Forward cache for listing AppDb dirs
 ///
 /// It's very expensive to list a dir and its sub-dirs one by one in multiple

app/lib/service.dart

@@ -10,6 +10,7 @@ import 'package:nc_photos/app_init.dart' as app_init;
 import 'package:nc_photos/app_localizations.dart';
 import 'package:nc_photos/di_container.dart';
 import 'package:nc_photos/entity/file.dart';
+import 'package:nc_photos/entity/file/data_source.dart';
 import 'package:nc_photos/entity/file_util.dart' as file_util;
 import 'package:nc_photos/event/event.dart';
 import 'package:nc_photos/event/native_event.dart';
@@ -230,6 +231,12 @@ class _MetadataTask {
       NativeEvent.fire(FileExifUpdatedEvent(_processedIds).toEvent());
       _processedIds = [];
     }
+
+    final c = KiwiContainer().resolve<DiContainer>();
+    if (c.fileRepo.dataSrc is FileCachedDataSource) {
+      await (c.fileRepo.dataSrc as FileCachedDataSource)
+          .updateRemoteTouchTokenNow();
+    }
   }
 
   Future<void> _updateMetadata() async {

app/lib/throttler.dart

@@ -1,7 +1,6 @@
 import 'dart:async';
 import 'dart:math' as math;
 
-import 'package:flutter/rendering.dart';
 import 'package:logging/logging.dart';
 import 'package:nc_photos/int_util.dart';
 
@@ -56,17 +55,30 @@ class Throttler<T> {
     _currentResponseTime = null;
     _count = 0;
     _maxCount = null;
+    // _data may be used else where, thus we must not call List.clear() here
     _data = <T>[];
   }
 
-  void _doTrigger() {
-    onTriggered?.call(_data);
-    clear();
+  Future<void> triggerNow() async {
+    if (_hasPendingEvent) {
+      _log.info("[triggerNow]$_logTag Triggered");
+      return _doTrigger();
+    }
   }
 
+  Future<void> _doTrigger() async {
+    if (_hasPendingEvent) {
+      final data = _data;
+      clear();
+      await onTriggered?.call(data);
+    }
+  }
+
+  bool get _hasPendingEvent => _count > 0;
+
   String get _logTag => logTag == null ? "" : "[$logTag]";
 
-  final ValueChanged<List<T>>? onTriggered;
+  final FutureOr<void> Function(List<T>)? onTriggered;
 
   /// Extra tag printed with logs from this class
   final String? logTag;