fix(ui): Change the behaviour when a duplicated event is received by the Timeline

crates/matrix-sdk-ui/src/timeline/inner/state.rs

@@ -501,7 +501,9 @@ impl TimelineInnerStateTransaction<'_> {
  timestamp: Some(event.origin_server_ts()),
  visible: false,
  };
- self.add_event(event_meta, position, room_data_provider, settings).await;
+ let _event_added_or_updated = self
+ .add_or_update_event(event_meta, position, room_data_provider, settings)
+ .await;
 
  return HandleEventResult::default();
  }
@@ -526,7 +528,9 @@ impl TimelineInnerStateTransaction<'_> {
  timestamp,
  visible: false,
  };
- self.add_event(event_meta, position, room_data_provider, settings).await;
+ let _event_added_or_updated = self
+ .add_or_update_event(event_meta, position, room_data_provider, settings)
+ .await;
  }
 
  return HandleEventResult::default();
@@ -543,7 +547,15 @@ impl TimelineInnerStateTransaction<'_> {
  timestamp: Some(timestamp),
  visible: should_add,
  };
- self.add_event(event_meta, position, room_data_provider, settings).await;
+
+ let event_added_or_updated =
+ self.add_or_update_event(event_meta, position, room_data_provider, settings).await;
+
+ // If the event has not been added or updated, it's because it's a duplicated
+ // event. Let's return early.
+ if !event_added_or_updated {
+ return HandleEventResult::default();
+ }
 
  let sender_profile = room_data_provider.profile_from_user_id(&sender).await;
  let ctx = TimelineEventContext {
@@ -637,23 +649,37 @@ impl TimelineInnerStateTransaction<'_> {
  items.commit();
  }
 
- async fn add_event<P: RoomDataProvider>(
+ /// Add or update an event in the [`TimelineInnerMeta::all_events`]
+ /// collection.
+ ///
+ /// This method also adjusts read receipt if needed.
+ ///
+ /// It returns `true` if the event has been added or updated, `false`
+ /// otherwise. The latter happens if the event already exists, i.e. if
+ /// an existing event is requested to be added.
+ async fn add_or_update_event<P: RoomDataProvider>(
  &mut self,
  event_meta: FullEventMeta<'_>,
  position: TimelineItemPosition,
  room_data_provider: &P,
  settings: &TimelineInnerSettings,
- ) {
+ ) -> bool {
+ // Detect if an event already exists in [`TimelineInnerMeta::all_events`]
+ fn event_already_exists(new_event_id: &EventId, all_events: &VecDeque<EventMeta>) -> bool {
+ all_events.iter().any(|EventMeta { event_id, .. }| event_id == new_event_id)
+ }
+
  match position {
  TimelineItemPosition::Start { .. } => {
+ if event_already_exists(event_meta.event_id, &self.meta.all_events) {
+ return false;
+ }
+
  self.meta.all_events.push_front(event_meta.base_meta())
  }
  TimelineItemPosition::End { .. } => {
- // Handle duplicated event.
- if let Some(pos) =
- self.meta.all_events.iter().position(|ev| ev.event_id == event_meta.event_id)
- {
- self.meta.all_events.remove(pos);
+ if event_already_exists(event_meta.event_id, &self.meta.all_events) {
+ return false;
  }
 
  self.meta.all_events.push_back(event_meta.base_meta());
@@ -686,6 +712,8 @@ impl TimelineInnerStateTransaction<'_> {
 
  self.maybe_add_implicit_read_receipt(event_meta);
  }
+
+ true
  }
 
  fn adjust_day_dividers(&mut self, mut adjuster: DayDividerAdjuster) {

crates/matrix-sdk-ui/tests/integration/timeline/sliding_sync.rs

@@ -416,10 +416,6 @@ async fn test_timeline_duplicated_events() -> Result<()> {
  assert_timeline_stream! {
  [timeline_stream]
  update[3] "$x3:bar.org";
- update[1] "$x1:bar.org";
- remove[1];
- append "$x1:bar.org";
- update[3] "$x1:bar.org";
  append "$x4:bar.org";
  };
  }