improved performance and battery usage on older devices

lib/api/cache_store.dart

@@ -0,0 +1,185 @@
+import 'dart:async';
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:flutter/foundation.dart';
+import 'package:path_provider/path_provider.dart';
+
+/// One cached response: the raw JSON payload and when it was stored.
+class CacheEntry {
+  final String json;
+  final int lastUpdate;
+
+  const CacheEntry({required this.json, required this.lastUpdate});
+}
+
+/// File-per-key store behind [RequestCache] and friends.
+///
+/// Replaces `localstore` for response caching: localstore reads and decodes
+/// the entire collection synchronously on first access, keeps every document
+/// in memory for the whole session and JSON-encodes payloads a second time.
+/// Here every access is async and touches exactly one file, and the payload is
+/// stored verbatim behind a one-line header (`<lastUpdate>\n<json>`).
+class CacheStore {
+  CacheStore._();
+
+  static final CacheStore instance = CacheStore._();
+
+  /// Payloads above this size are decoded on a background isolate.
+  static const int isolateDecodeThreshold = 64 * 1024;
+
+  Future<Directory>? _dir;
+  final Map<String, Future<void>> _writes = {};
+
+  Future<Directory> _directory() => _dir ??= () async {
+    final base = await getApplicationCacheDirectory();
+    final dir = Directory('${base.path}/request_cache');
+    await dir.create(recursive: true);
+    return dir;
+  }();
+
+  Future<File> _file(String key) async =>
+      File('${(await _directory()).path}/${_safeName(key)}');
+
+  /// Keys are internal ids (`nc-chat-<token>`, `wd-folder-<md5>`); only path
+  /// separators would be a problem in a file name.
+  static String _safeName(String key) => key.replaceAll(RegExp(r'[/\\]'), '_');
+
+  Future<CacheEntry?> read(String key) async {
+    try {
+      await _writes[key];
+      return parse(await (await _file(key)).readAsString());
+    } on Object {
+      // Missing (PathNotFoundException) or unreadable: a cache miss.
+      return null;
+    }
+  }
+
+  /// All entries whose key starts with [prefix], read concurrently.
+  Future<Map<String, CacheEntry>> readAll({String prefix = ''}) async {
+    final keys = await this.keys(prefix: prefix);
+    final entries = await Future.wait(keys.map(read));
+    return {for (var i = 0; i < keys.length; i++) keys[i]: ?entries[i]};
+  }
+
+  Future<void> write(String key, String json) {
+    final previous = _writes[key] ?? Future<void>.value();
+    late final Future<void> current;
+    current = previous.then((_) => _write(key, json)).whenComplete(() {
+      if (identical(_writes[key], current)) _writes.remove(key);
+    });
+    return _writes[key] = current;
+  }
+
+  Future<void> _write(String key, String json) async {
+    try {
+      final file = await _file(key);
+      // Write-then-rename so a reader (or the widget background isolate)
+      // never sees a half-written file.
+      final tmp = File('${file.path}.tmp');
+      await tmp.writeAsString(
+        '${DateTime.now().millisecondsSinceEpoch}\n$json',
+        flush: true,
+      );
+      await tmp.rename(file.path);
+    } on Object catch (e) {
+      debugPrint('CacheStore.write($key) failed: $e');
+    }
+  }
+
+  Future<void> delete(String key) async {
+    try {
+      await _writes[key];
+      await (await _file(key)).delete();
+    } on Object {
+      // A missing or locked file is as good as deleted for a cache.
+    }
+  }
+
+  Future<void> clear() async {
+    try {
+      final dir = await _directory();
+      if (dir.existsSync()) await dir.delete(recursive: true);
+    } on Object catch (e) {
+      debugPrint('CacheStore.clear failed: $e');
+    }
+    _dir = null;
+  }
+
+  /// All stored keys, optionally filtered by [prefix].
+  Future<List<String>> keys({String prefix = ''}) async {
+    try {
+      final dir = await _directory();
+      return [
+        await for (final entity in dir.list())
+          if (entity is File && !entity.path.endsWith('.tmp'))
+            if (entity.uri.pathSegments.last case final name
+                when name.startsWith(prefix))
+              name,
+      ];
+    } on Object {
+      return const [];
+    }
+  }
+
+  /// Removes entries not written for [maxAge], judged by file mtime so nothing
+  /// has to be read or decoded.
+  Future<void> deleteOlderThan(Duration maxAge) async {
+    try {
+      final dir = await _directory();
+      final cutoff = DateTime.now().subtract(maxAge);
+      await for (final entity in dir.list()) {
+        if (entity is! File) continue;
+        // ignore: avoid_slow_async_io
+        final modified = (await entity.stat()).modified;
+        if (modified.isBefore(cutoff)) await entity.delete();
+      }
+    } on Object catch (e) {
+      debugPrint('CacheStore.deleteOlderThan failed: $e');
+    }
+  }
+
+  /// Total size of all entries in bytes.
+  Future<int> totalSize() async {
+    try {
+      final dir = await _directory();
+      var sum = 0;
+      await for (final entity in dir.list()) {
+        if (entity is File) sum += await entity.length();
+      }
+      return sum;
+    } on Object {
+      return 0;
+    }
+  }
+
+  /// Parses the stored file format; public for tests.
+  static CacheEntry? parse(String raw) {
+    final newline = raw.indexOf('\n');
+    if (newline < 0) return null;
+    final lastUpdate = int.tryParse(raw.substring(0, newline));
+    if (lastUpdate == null) return null;
+    return CacheEntry(json: raw.substring(newline + 1), lastUpdate: lastUpdate);
+  }
+
+  /// Decodes a cached payload, off the UI isolate when it is large.
+  static Future<Map<String, dynamic>> decode(String json) =>
+      json.length > isolateDecodeThreshold
+      ? compute(_decodeMap, json)
+      : Future.value(_decodeMap(json));
+
+  static Map<String, dynamic> _decodeMap(String json) =>
+      jsonDecode(json) as Map<String, dynamic>;
+
+  /// Deletes the directory the old localstore-based cache lived in. It is
+  /// never read again and would otherwise linger with up to 200 days of data.
+  static Future<void> deleteLegacyLocalstoreCache() async {
+    try {
+      final docs = await getApplicationDocumentsDirectory();
+      final legacy = Directory('${docs.path}/MarianumMobile');
+      if (legacy.existsSync()) await legacy.delete(recursive: true);
+    } on Object catch (e) {
+      debugPrint('Legacy cache cleanup failed: $e');
+    }
+  }
+}

lib/api/marianumcloud/talk/chat/get_chat_cache.dart

@@ -17,7 +17,7 @@ class GetChatCache extends SimpleCache<GetChatResponse> {
              lookIntoFuture: GetChatParamsSwitch.off,
              setReadMarker: GetChatParamsSwitch.on,
              // Small initial page; also the per-chat offline snapshot written to
-             // localstore. Older messages are paged in on scroll-up via
+             // the request cache. Older messages are paged in on scroll-up via
              // GetChatHistory. Keep in sync with ChatBloc's _kInitialPageSize.
              limit: 50,
            ),

lib/api/marianumcloud/talk/chat/get_chat_history.dart

@@ -1,3 +1,4 @@
+import 'package:flutter/foundation.dart';
 import 'package:http/http.dart' as http;
 
 import '../../../errors/server_exception.dart';
@@ -45,8 +46,10 @@ class GetChatHistory {
     final status = response.statusCode;
     if (status == 304) return null;
     if (status >= 200 && status < 300) {
-      return GetChatResponse.fromJson(NextcloudOcs.decode(response.body))
-        ..headers = response.headers;
+      // A page holds up to 200 messages and lands while the user is scrolling;
+      // decoding it on the UI isolate stalls the fling.
+      final parsed = await compute(_parseChatResponse, response.body);
+      return parsed..headers = response.headers;
     }
     throw ServerException(
       statusCode: status,
@@ -54,3 +57,6 @@ class GetChatHistory {
     );
   }
 }
+
+GetChatResponse _parseChatResponse(String body) =>
+    GetChatResponse.fromJson(NextcloudOcs.decode(body));

lib/api/marianumcloud/talk/room/get_room.dart

@@ -1,3 +1,4 @@
+import 'package:flutter/foundation.dart';
 import 'package:http/http.dart' as http;
 
 import '../../nextcloud_ocs.dart';
@@ -10,8 +11,12 @@ class GetRoom extends TalkApi<GetRoomResponse> {
   GetRoom(this.params) : super('v4/room', null, getParameters: params.toJson());
 
   @override
-  GetRoomResponse assemble(String raw) =>
-      GetRoomResponse.fromJson(NextcloudOcs.decode(raw));
+  GetRoomResponse assemble(String raw) => _parseRooms(raw);
+
+  // The room list with status is 100–250 KB and polled every 15–60 s.
+  @override
+  Future<GetRoomResponse> assembleAsync(String raw) =>
+      compute(_parseRooms, raw);
 
   @override
   Future<http.Response> request(
@@ -20,3 +25,6 @@ class GetRoom extends TalkApi<GetRoomResponse> {
     Map<String, String>? headers,
   ) => http.get(uri, headers: headers);
 }
+
+GetRoomResponse _parseRooms(String raw) =>
+    GetRoomResponse.fromJson(NextcloudOcs.decode(raw));

lib/api/marianumcloud/talk/talk_api.dart

@@ -30,6 +30,10 @@ abstract class TalkApi<T extends ApiResponse?> {
   );
   T assemble(String raw);
 
+  /// Override to parse large payloads off the UI isolate (e.g. via `compute`
+  /// with a top-level parser); defaults to the synchronous [assemble].
+  Future<T> assembleAsync(String raw) async => assemble(raw);
+
   Future<T> run() async {
     final endpoint = NextcloudOcs.uri(
       'apps/spreed/api/$path',
@@ -69,7 +73,7 @@ abstract class TalkApi<T extends ApiResponse?> {
     }
 
     try {
-      final assembled = assemble(data.body);
+      final assembled = await assembleAsync(data.body);
       assembled?.headers = data.headers;
       return assembled;
     } catch (e) {

lib/api/marianumcloud/webdav/queries/list_files/cacheable_file.dart

@@ -29,6 +29,19 @@ class CacheableFile {
   /// file/folder in the list. Nullable so older cached entries decode fine.
   bool? isSharedWithMe;
 
+  /// Lower-cased [name] for sorting/filtering, cached because comparators
+  /// call it for every comparison (name is mutable, hence the identity check).
+  String get lowerName {
+    if (!identical(_lowerNameFor, name)) {
+      _lowerNameFor = name;
+      _lowerName = name.toLowerCase();
+    }
+    return _lowerName;
+  }
+
+  String? _lowerNameFor;
+  String _lowerName = '';
+
   CacheableFile({
     required this.path,
     required this.isDirectory,

lib/api/marianumcloud/webdav/queries/list_files/list_files_cache.dart

@@ -1,9 +1,9 @@
 import 'dart:convert';
 
 import 'package:crypto/crypto.dart';
-import 'package:localstore/localstore.dart';
 
 import '../../../../../utils/cache_invalidation_bus.dart';
+import '../../../../cache_store.dart';
 import '../../../../request_cache.dart';
 import 'list_files.dart';
 import 'list_files_params.dart';
@@ -43,14 +43,11 @@ class ListFilesCache extends SimpleCache<ListFilesResponse> {
   /// (slow) root listing is already populated by the time the user
   /// navigates to the Files module.
   ///
-  /// No-ops when a cached root payload is already present in localstore —
+  /// No-ops when a cached root payload is already present in the cache —
   /// the regular TTL handling in [RequestCache] takes over from there.
   static Future<void> prefetchRootListing() async {
     const rootPath = '';
-    final cached = await Localstore.instance
-        .collection(RequestCache.collection)
-        .doc(_documentId(rootPath))
-        .get();
+    final cached = await CacheStore.instance.read(_documentId(rootPath));
     if (cached != null) return;
     // Drive the same code path as a regular fetch so the result lands in
     // the cache; we don't care about the in-memory callback here.
@@ -69,10 +66,7 @@ class ListFilesCache extends SimpleCache<ListFilesResponse> {
   /// `_FilesView` for that path via [CacheInvalidationBus] so it refetches
   /// even while it is sitting in the background of the navigation stack.
   static Future<void> invalidate(String path) async {
-    await Localstore.instance
-        .collection(RequestCache.collection)
-        .doc(_documentId(path))
-        .delete();
+    await CacheStore.instance.delete(_documentId(path));
     CacheInvalidationBus.notifyListFiles(path);
   }
 }

lib/api/marianumconnect/queries/timetable_custom_events/custom_events_migration.dart

@@ -1,6 +1,6 @@
 import 'dart:developer';
 
-import 'package:localstore/localstore.dart';
+import 'package:shared_preferences/shared_preferences.dart';
 
 import '../../../../model/account_data.dart';
 import '../../../demo/demo_mode.dart';
@@ -21,9 +21,7 @@ import 'timetable_custom_events_add.dart';
 /// failure only sees the events that were not yet moved, so nothing is
 /// duplicated. The flag is set only once MHSL reports no remaining events.
 class CustomEventsMigration {
-  static const String _collection = 'MarianumMobile';
-  static const String _document = 'customEventsMigration';
-  static const String _doneKey = 'migratedToMc';
+  static const String _doneKey = 'customEventsMigratedToMc';
 
   const CustomEventsMigration._();
 
@@ -57,17 +55,11 @@ class CustomEventsMigration {
     }
   }
 
-  static Future<bool> _isDone() async {
-    final data = await Localstore.instance
-        .collection(_collection)
-        .doc(_document)
-        .get();
-    return data != null && data[_doneKey] == true;
-  }
+  // SharedPreferences, like the old cache document, is cleared on sign-out,
+  // so the next account runs its own migration.
+  static Future<bool> _isDone() async =>
+      (await SharedPreferences.getInstance()).getBool(_doneKey) ?? false;
 
-  static Future<void> _markDone() async {
-    await Localstore.instance.collection(_collection).doc(_document).set({
-      _doneKey: true,
-    });
-  }
+  static Future<void> _markDone() async =>
+      (await SharedPreferences.getInstance()).setBool(_doneKey, true);
 }

lib/api/marianumconnect/queries/timetable_get_week/timetable_get_week_response.dart

@@ -76,10 +76,17 @@ class McTimetableEntry {
 
   /// Combines the calendar date with the hour/minute portion of [startTime]
   /// (which carries a 1970 placeholder date) into a real DateTime.
-  DateTime get startDateTime =>
+  DateTime get startDateTime => _startDateTime;
+
+  DateTime get endDateTime => _endDateTime;
+
+  // Cached (private, so json_serializable ignores them): sorting and lesson
+  // merging read these per comparison, and every local DateTime construction
+  // does a timezone lookup.
+  late final DateTime _startDateTime =
       DateTime(date.year, date.month, date.day, startTime.hour, startTime.minute);
 
-  DateTime get endDateTime =>
+  late final DateTime _endDateTime =
       DateTime(date.year, date.month, date.day, endTime.hour, endTime.minute);
 
   static DateTime _dateFromJson(String raw) => DateTime.parse(raw);

lib/api/request_cache.dart

@@ -1,10 +1,9 @@
 import 'dart:async';
 import 'dart:convert';
 
-import 'package:localstore/localstore.dart';
-
 import '../model/account_data.dart';
 import 'api_response.dart';
+import 'cache_store.dart';
 import 'errors/parse_exception.dart';
 import 'errors/stale_session_exception.dart';
 
@@ -14,12 +13,10 @@ abstract class RequestCache<T extends ApiResponse?> {
   static const int cacheHour = 60 * 60;
   static const int cacheDay = 60 * 60 * 24;
 
-  static String collection = 'MarianumMobile';
-
   int maxCacheTime;
   void Function(T)? onUpdate;
 
-  /// Called only when [start] finds a cached payload in localstore. Use this
+  /// Called only when [start] finds a cached payload in the [CacheStore]. Use this
   /// (instead of [onUpdate]) when callers need to distinguish stale-but-fast
   /// cache hits from authoritative network responses.
   void Function(T)? onCacheData;
@@ -52,47 +49,55 @@ abstract class RequestCache<T extends ApiResponse?> {
   Future<void> start(String document) async {
     final epoch = AccountData().sessionEpoch;
     try {
-      final tableData = await Localstore.instance
-          .collection(collection)
-          .doc(document)
-          .get();
-      if (tableData != null) {
-        final cached = onLocalData(tableData['json'] as String);
+      final entry = await CacheStore.instance.read(document);
+      var lastUpdate = entry?.lastUpdate ?? 0;
+      T? cached;
+      if (entry != null) {
+        try {
+          cached = fromCacheJson(await CacheStore.decode(entry.json));
+        } on Object {
+          // A payload from an older model version: treat it as a miss.
+          await CacheStore.instance.delete(document);
+          lastUpdate = 0;
+        }
+      }
+      if (cached != null) {
         onUpdate?.call(cached);
         onCacheData?.call(cached);
       }
-
-      final lastUpdate = (tableData?['lastupdate'] as num?) ?? 0;
-      if (DateTime.now().millisecondsSinceEpoch - (maxCacheTime * 1000) <
-          lastUpdate) {
-        if (renew == null || !renew!) return;
-      }
-
-      try {
-        final newValue = await onLoad();
-        // The collection is shared, so a late response of a signed-out
-        // account would otherwise be cached for the next one.
-        if (!AccountData().isCurrentSession(epoch)) {
-          onError(const StaleSessionException());
-          return;
-        }
-        onUpdate?.call(newValue);
-        onNetworkData?.call(newValue);
-        unawaited(
-          Localstore.instance.collection(collection).doc(document).set({
-            'json': jsonEncode(newValue),
-            'lastupdate': DateTime.now().millisecondsSinceEpoch,
-          }),
-        );
-      } on Exception catch (e) {
-        onError(e);
-      }
+      await _load(document, epoch, lastUpdate: lastUpdate);
     } finally {
       if (!_ready.isCompleted) _ready.complete();
     }
   }
 
-  T onLocalData(String json);
+  Future<void> _load(
+    String document,
+    int epoch, {
+    required int lastUpdate,
+  }) async {
+    if (DateTime.now().millisecondsSinceEpoch - (maxCacheTime * 1000) <
+        lastUpdate) {
+      if (renew == null || !renew!) return;
+    }
+
+    try {
+      final newValue = await onLoad();
+      // The cache is shared, so a late response of a signed-out
+      // account would otherwise be cached for the next one.
+      if (!AccountData().isCurrentSession(epoch)) {
+        onError(const StaleSessionException());
+        return;
+      }
+      onUpdate?.call(newValue);
+      onNetworkData?.call(newValue);
+      unawaited(CacheStore.instance.write(document, jsonEncode(newValue)));
+    } on Exception catch (e) {
+      onError(e);
+    }
+  }
+
+  T fromCacheJson(Map<String, dynamic> json);
   Future<T> onLoad();
 }
 
@@ -126,8 +131,7 @@ class SimpleCache<T extends ApiResponse?> extends RequestCache<T> {
   Future<T> onLoad() => _loader();
 
   @override
-  T onLocalData(String json) =>
-      _fromJson(jsonDecode(json) as Map<String, dynamic>);
+  T fromCacheJson(Map<String, dynamic> json) => _fromJson(json);
 }
 
 /// Captures the latest cache payload (cached or network) and rethrows the