base: move the initial filling of the display name cache into the sync methods

It's not perfect, but it's honest work.

crates/matrix-sdk-base/src/client.rs

@@ -1071,6 +1071,13 @@ impl BaseClient {
             self.apply_changes(&changes, false);
         }
 
+        // Now that all the rooms information have been saved, update the display name
+        // cache (which relies on information stored in the database). This will
+        // live in memory, until the next sync which will saves the room info to
+        // disk; we do this to avoid saving that would be redundant with the
+        // above. Oh well.
+        new_rooms.update_in_memory_caches(&self.store).await;
+
         info!("Processed a sync response in {:?}", now.elapsed());
 
         let response = SyncResponse {

crates/matrix-sdk-base/src/sliding_sync.rs

@@ -295,6 +295,13 @@ impl BaseClient {
         self.apply_changes(&changes, false);
         trace!("applied changes");
 
+        // Now that all the rooms information have been saved, update the display name
+        // cache (which relies on information stored in the database). This will
+        // live in memory, until the next sync which will saves the room info to
+        // disk; we do this to avoid saving that would be redundant with the
+        // above. Oh well.
+        new_rooms.update_in_memory_caches(&self.store).await;
+
         Ok(SyncResponse {
             rooms: new_rooms,
             notifications,

crates/matrix-sdk-base/src/sync.rs

@@ -35,6 +35,7 @@ use serde::{Deserialize, Serialize};
 use crate::{
     debug::{DebugInvitedRoom, DebugListOfRawEvents, DebugListOfRawEventsNoId},
     deserialized_responses::{AmbiguityChange, RawAnySyncOrStrippedTimelineEvent},
+    store::Store,
 };
 
 /// Generalized representation of a `/sync` response.
@@ -78,6 +79,23 @@ pub struct RoomUpdates {
     pub invite: BTreeMap<OwnedRoomId, InvitedRoomUpdate>,
 }
 
+impl RoomUpdates {
+    /// Update the caches for the rooms that received updates.
+    ///
+    /// This will only fill the in-memory caches, not save the info on disk.
+    pub(crate) async fn update_in_memory_caches(&self, store: &Store) {
+        for room in self
+            .leave
+            .keys()
+            .chain(self.join.keys())
+            .chain(self.invite.keys())
+            .filter_map(|room_id| store.get_room(room_id))
+        {
+            let _ = room.compute_display_name().await;
+        }
+    }
+}
+
 #[cfg(not(tarpaulin_include))]
 impl fmt::Debug for RoomUpdates {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {

crates/matrix-sdk/src/sync.rs

@@ -154,19 +154,6 @@ impl Client {
     ) -> Result<()> {
         let BaseSyncResponse { rooms, presence, account_data, to_device, notifications } = response;
 
-        {
-            // Recompute the computed display name for all the rooms which had an update.
-            for room in rooms
-                .leave
-                .keys()
-                .chain(rooms.join.keys())
-                .chain(rooms.invite.keys())
-                .filter_map(|room_id| self.get_room(room_id))
-            {
-                let _ = room.compute_display_name().await;
-            }
-        }
-
         let now = Instant::now();
         self.handle_sync_events(HandlerKind::GlobalAccountData, None, account_data).await?;
         self.handle_sync_events(HandlerKind::Presence, None, presence).await?;