Wrap buffer ids in Arc instead of cloning them

According to callgrind, a lot of time was spent in alloc/free for OwnedRoomId
structs contained in BufferId, even in release mode.

src/app.rs

@@ -372,7 +372,7 @@ impl App {
     client: matrix_sdk::Client,
     sync_response: matrix_sdk::sync::SyncResponse,
   ) -> Result<()> {
-    let known_rooms: HashSet<matrix_sdk::ruma::OwnedRoomId> = self
+    let known_rooms: HashSet<Arc<matrix_sdk::ruma::OwnedRoomId>> = self
       .buffers
       .iter()
       .flat_map(|buf| match buf.id() {
@@ -385,7 +385,7 @@ impl App {
       .join
       .keys()
       .filter(|room_id: &&matrix_sdk::ruma::OwnedRoomId| {
-        !known_rooms.contains::<matrix_sdk::ruma::RoomId>(room_id.as_ref())
+        !known_rooms.contains(&Arc::new((*room_id).clone()))
       })
       .map(|room_id| (client.clone(), room_id.to_owned()))
       .collect();
@@ -399,7 +399,7 @@ impl App {
   ) {
     futures::future::join_all(
       rooms
-        .map(|(client, room)| RoomBuffer::new(self.config.clone(), client, room))
+        .map(|(client, room)| RoomBuffer::new(self.config.clone(), client, Arc::new(room)))
         .map(|fut| fut.map(|res| res.expect("Failed to create RoomBuffer at startup"))),
     )
     .await

src/buffers/mod.rs

@@ -16,6 +16,7 @@
 
 use std::cmp::Ordering;
 use std::collections::{HashMap, HashSet};
+use std::sync::Arc;
 
 use futures::stream::FuturesUnordered;
 use futures::StreamExt;
@@ -47,7 +48,7 @@ pub enum BufferId {
   /// The main/home buffer
   Log,
   /// Any Matrix room
-  Room(matrix_sdk::ruma::OwnedRoomId),
+  Room(Arc<matrix_sdk::ruma::OwnedRoomId>),
 }
 
 /// Values should follow the ["Ordering of children within a space" algorithm](https://spec.matrix.org/v1.8/client-server-api/#ordering-of-children-within-a-space).

src/buffers/room.rs

@@ -118,7 +118,7 @@ impl DynamicUsage for OwnedBufferItemContent {
 
 pub struct SingleClientRoomBuffer {
   config: Arc<Config>,
-  room_id: OwnedRoomId,
+  room_id: Arc<OwnedRoomId>,
   client: Client,
 
   /// Newest first
@@ -474,7 +474,7 @@ impl SingleClientRoomBuffer {
 pub struct RoomBuffer {
   config: Arc<Config>,
 
-  room_id: OwnedRoomId,
+  room_id: Arc<OwnedRoomId>,
 
   computed_roominfo: Option<ComputedRoomInfo>,
 
@@ -509,7 +509,7 @@ impl RoomBuffer {
   pub async fn new(
     config: Arc<Config>,
     initial_client: Client,
-    room_id: OwnedRoomId,
+    room_id: Arc<OwnedRoomId>,
   ) -> Result<Self> {
     let mut self_ = RoomBuffer {
       config,
@@ -589,7 +589,7 @@ impl Buffer for RoomBuffer {
   }
 
   fn id(&self) -> BufferId {
-    BufferId::Room(self.room_id.to_owned())
+    BufferId::Room(self.room_id.clone())
   }
 
   fn parent(&self) -> Option<BufferId> {
@@ -597,7 +597,7 @@ impl Buffer for RoomBuffer {
       .computed_roominfo
       .as_ref()
       .and_then(|roominfo| roominfo.parent.as_ref())
-      .map(|parent| BufferId::Room(parent.to_owned()))
+      .map(|parent| BufferId::Room(parent.clone()))
   }
   fn children(&self) -> Option<SortedVec<(BufferSortKey, BufferId)>> {
     self
@@ -607,7 +607,7 @@ impl Buffer for RoomBuffer {
       .map(|children: &SortedVec<_>| {
         let children = children
           .iter()
-          .map(|(sort_key, room_id)| (sort_key.clone(), BufferId::Room(room_id.to_owned())))
+          .map(|(sort_key, room_id)| (sort_key.clone(), BufferId::Room(room_id.clone())))
           .collect();
         // This is safe because the map above preserves order
         unsafe { SortedVec::from_sorted(children) }
@@ -833,6 +833,7 @@ async fn compute_room_info(
             })
             .next() // Get the first one to be ready. TODO: take the canonical space
             .await
+            .map(Arc::new)
         },
         Err(e) => {
           tracing::error!("Failed to get parent spaces of {}: {:?}", room.room_id(), e);
@@ -858,7 +859,7 @@ async fn compute_room_info(
                       explicit_order: e.content.order,
                       origin_server_ts: Some(e.origin_server_ts),
                     },
-                    e.state_key.to_owned(),
+                    Arc::new(e.state_key.to_owned()),
                   )),
                   Ok(SyncOrStrippedState::Sync(SyncStateEvent::Redacted(_))) => None,
                   Ok(SyncOrStrippedState::Stripped(e)) => Some((
@@ -866,7 +867,7 @@ async fn compute_room_info(
                       explicit_order: None,
                       origin_server_ts: None, // Why don't stripped events have origin_server_ts!?
                     },
-                    e.state_key.to_owned(),
+                    Arc::new(e.state_key.to_owned()),
                   )),
 
                   Err(_) => None, // Ignore deserialization errors
@@ -941,8 +942,8 @@ async fn compute_room_info(
 #[derive(Debug)]
 struct ComputedRoomInfo {
   display_name: Option<DisplayName>,
-  parent: Option<OwnedRoomId>,
-  children: Option<SortedVec<(BufferSortKey, OwnedRoomId)>>,
+  parent: Option<Arc<OwnedRoomId>>,
+  children: Option<SortedVec<(BufferSortKey, Arc<OwnedRoomId>)>>,
   /// `None` if unknown, `Some(None)` if nothing is read, `Some(Some(last_fully_read_event_id))`
   /// otherwise
   fully_read_at: Option<Option<OwnedEventId>>,