From fc8625d30e78b5dcc87c0c767d225500903cf9ba Mon Sep 17 00:00:00 2001
From: Sorunome <mail@sorunome.de>
Date: Thu, 21 May 2020 14:52:14 +0000
Subject: [PATCH] clear timeline events cache on limited updates

---
 lib/src/timeline.dart   |  8 ++++++++
 test/timeline_test.dart | 15 +++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/lib/src/timeline.dart b/lib/src/timeline.dart
index 9b765f8..9cb0762 100644
--- a/lib/src/timeline.dart
+++ b/lib/src/timeline.dart
@@ -26,6 +26,7 @@ import 'dart:async';
 import 'event.dart';
 import 'room.dart';
 import 'sync/event_update.dart';
+import 'sync/room_update.dart';
 
 typedef onTimelineUpdateCallback = void Function();
 typedef onTimelineInsertCallback = void Function(int insertID);
@@ -41,6 +42,7 @@ class Timeline {
   final onTimelineInsertCallback onInsert;
 
   StreamSubscription<EventUpdate> sub;
+  StreamSubscription<RoomUpdate> roomSub;
   StreamSubscription<String> sessionIdReceivedSub;
   bool _requestingHistoryLock = false;
 
@@ -77,6 +79,11 @@ class Timeline {
 
   Timeline({this.room, this.events, this.onUpdate, this.onInsert}) {
     sub ??= room.client.onEvent.stream.listen(_handleEventUpdate);
+    // if the timeline is limited we want to clear our events cache
+    // as r.limitedTimeline can be "null" sometimes, we need to check for == true
+    // as after receiving a limited timeline room update new events are expected
+    // to be received via the onEvent stream, it is unneeded to call sortAndUpdate
+    roomSub ??= room.client.onRoomUpdate.stream.where((r) => r.id == room.id && r.limitedTimeline == true).listen((r) => events.clear());
     sessionIdReceivedSub ??=
         room.onSessionKeyReceived.stream.listen(_sessionKeyReceived);
   }
@@ -84,6 +91,7 @@ class Timeline {
   /// Don't forget to call this before you dismiss this object!
   void cancelSubscriptions() {
     sub?.cancel();
+    roomSub?.cancel();
     sessionIdReceivedSub?.cancel();
   }
 
diff --git a/test/timeline_test.dart b/test/timeline_test.dart
index 28c006f..e2cda2e 100644
--- a/test/timeline_test.dart
+++ b/test/timeline_test.dart
@@ -26,7 +26,9 @@ import 'package:test/test.dart';
 import 'package:famedlysdk/src/client.dart';
 import 'package:famedlysdk/src/room.dart';
 import 'package:famedlysdk/src/timeline.dart';
+import 'package:famedlysdk/src/user.dart';
 import 'package:famedlysdk/src/sync/event_update.dart';
+import 'package:famedlysdk/src/sync/room_update.dart';
 import 'fake_matrix_api.dart';
 
 void main() {
@@ -240,5 +242,18 @@ void main() {
       expect(timeline.events[8].eventId, '1143273582443PhrSn:example.org');
       expect(room.prev_batch, 't47409-4357353_219380_26003_2265');
     });
+
+    test('Clear cache on limited timeline', () async {
+      client.onRoomUpdate.add(RoomUpdate(
+        id: roomID,
+        membership: Membership.join,
+        notification_count: 0,
+        highlight_count: 0,
+        limitedTimeline: true,
+        prev_batch: 'blah',
+      ));
+      await Future.delayed(Duration(milliseconds: 50));
+      expect(timeline.events.isEmpty, true);
+    });
   });
 }