base: Box large RoomInfo fields

RoomInfo is often passed around by value, including in futures where
holding types with a large stack size is especially problematic¹.
It might make sense to move the actual data of (Base)RoomInfo into
an inner struct that is always held inside a Box or Arc, but this change
should have most of the benefits of that while being a bit simpler.

¹ rust-lang/rust#69826

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

@@ -620,7 +620,10 @@ impl BaseClient {
     /// decrypted event if we found one, along with its index in the
     /// latest_encrypted_events list, or None if we didn't find one.
     #[cfg(all(feature = "e2e-encryption", feature = "experimental-sliding-sync"))]
-    async fn decrypt_latest_suitable_event(&self, room: &Room) -> Option<(LatestEvent, usize)> {
+    async fn decrypt_latest_suitable_event(
+        &self,
+        room: &Room,
+    ) -> Option<(Box<LatestEvent>, usize)> {
         let enc_events = room.latest_encrypted_events();
 
         // Walk backwards through the encrypted events, looking for one we can decrypt
@@ -633,7 +636,7 @@ impl BaseClient {
                         is_suitable_for_latest_event(&any_sync_event)
                     {
                         // The event is the right type for us to use as latest_event
-                        return Some((LatestEvent::new(decrypted), i));
+                        return Some((Box::new(LatestEvent::new(decrypted)), i));
                     }
                 }
             }

crates/matrix-sdk-base/src/rooms/normal.rs

@@ -403,12 +403,12 @@ impl Room {
     /// sliding sync.
     #[cfg(feature = "experimental-sliding-sync")]
     pub fn latest_event(&self) -> Option<LatestEvent> {
-        self.inner.read().latest_event.clone()
+        self.inner.read().latest_event.as_deref().cloned()
     }
 
     /// Update the last event in the room
     #[cfg(all(feature = "e2e-encryption", feature = "experimental-sliding-sync"))]
-    pub(crate) fn set_latest_event(&self, latest_event: Option<LatestEvent>) {
+    pub(crate) fn set_latest_event(&self, latest_event: Option<Box<LatestEvent>>) {
         self.inner.update(|info| info.latest_event = latest_event);
     }
 
@@ -429,7 +429,7 @@ impl Room {
     /// Panics if index is not a valid index in the latest_encrypted_events
     /// list.
     #[cfg(all(feature = "e2e-encryption", feature = "experimental-sliding-sync"))]
-    pub(crate) fn on_latest_event_decrypted(&self, latest_event: LatestEvent, index: usize) {
+    pub(crate) fn on_latest_event_decrypted(&self, latest_event: Box<LatestEvent>, index: usize) {
         self.set_latest_event(Some(latest_event));
         self.latest_encrypted_events.write().unwrap().drain(0..=index);
     }
@@ -732,10 +732,10 @@ pub struct RoomInfo {
     pub(crate) encryption_state_synced: bool,
     /// The last event send by sliding sync
     #[cfg(feature = "experimental-sliding-sync")]
-    pub(crate) latest_event: Option<LatestEvent>,
+    pub(crate) latest_event: Option<Box<LatestEvent>>,
     /// Base room info which holds some basic event contents important for the
     /// room state.
-    pub(crate) base_info: BaseRoomInfo,
+    pub(crate) base_info: Box<BaseRoomInfo>,
 }
 
 #[derive(Clone, Debug, Serialize, Deserialize, PartialEq, Eq)]
@@ -769,7 +769,7 @@ impl RoomInfo {
             encryption_state_synced: false,
             #[cfg(feature = "experimental-sliding-sync")]
             latest_event: None,
-            base_info: BaseRoomInfo::new(),
+            base_info: Box::new(BaseRoomInfo::new()),
         }
     }
 
@@ -1246,10 +1246,10 @@ mod tests {
             last_prev_batch: Some("pb".to_owned()),
             sync_info: SyncInfo::FullySynced,
             encryption_state_synced: true,
-            latest_event: Some(LatestEvent::new(
+            latest_event: Some(Box::new(LatestEvent::new(
                 Raw::from_json_string(json!({"sender": "@u:i.uk"}).to_string()).unwrap().into(),
-            )),
-            base_info: BaseRoomInfo::new(),
+            ))),
+            base_info: Box::new(BaseRoomInfo::new()),
         };
 
         let info_json = json!({
@@ -1698,10 +1698,10 @@ mod tests {
     }
 
     #[cfg(feature = "experimental-sliding-sync")]
-    fn make_latest_event(event_id: &str) -> LatestEvent {
-        LatestEvent::new(SyncTimelineEvent::new(
+    fn make_latest_event(event_id: &str) -> Box<LatestEvent> {
+        Box::new(LatestEvent::new(SyncTimelineEvent::new(
             Raw::from_json_string(json!({ "event_id": event_id }).to_string()).unwrap(),
-        ))
+        )))
     }
 
     fn timestamp(minutes_ago: u32) -> MilliSecondsSinceUnixEpoch {

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

@@ -524,11 +524,11 @@ async fn cache_latest_events(
                         }
                     }
 
-                    let latest_event = LatestEvent::new_with_sender_details(
+                    let latest_event = Box::new(LatestEvent::new_with_sender_details(
                         event.clone(),
                         sender_profile,
                         sender_name_is_ambiguous,
-                    );
+                    ));
 
                     // Store it in the return RoomInfo, and in the Room, to make sure they are
                     // consistent

crates/matrix-sdk-base/src/store/migration_helpers.rs

@@ -117,7 +117,7 @@ impl RoomInfoV1 {
             sync_info,
             encryption_state_synced,
             #[cfg(feature = "experimental-sliding-sync")]
-            latest_event: latest_event.map(LatestEvent::new),
+            latest_event: latest_event.map(|ev| Box::new(LatestEvent::new(ev))),
             base_info: base_info.migrate(create),
         }
     }
@@ -157,7 +157,10 @@ struct BaseRoomInfoV1 {
 
 impl BaseRoomInfoV1 {
     /// Migrate this to a [`BaseRoomInfo`].
-    fn migrate(self, create: Option<&SyncOrStrippedState<RoomCreateEventContent>>) -> BaseRoomInfo {
+    fn migrate(
+        self,
+        create: Option<&SyncOrStrippedState<RoomCreateEventContent>>,
+    ) -> Box<BaseRoomInfo> {
         let BaseRoomInfoV1 {
             avatar,
             canonical_alias,
@@ -186,7 +189,7 @@ impl BaseRoomInfoV1 {
             MinimalStateEvent::Redacted(ev) => MinimalStateEvent::Redacted(ev),
         });
 
-        BaseRoomInfo {
+        Box::new(BaseRoomInfo {
             avatar,
             canonical_alias,
             create,
@@ -200,7 +203,7 @@ impl BaseRoomInfoV1 {
             tombstone,
             topic,
             rtc_member: BTreeMap::new(),
-        }
+        })
     }
 }