⚡ Bolt: Optimize HashMap hasher for room lookups

src/sliding_sync.rs

@@ -26,7 +26,7 @@ use tokio::{
     sync::{mpsc::{Sender, UnboundedReceiver, UnboundedSender}, watch, Notify}, task::JoinHandle, time::error::Elapsed,
 };
 use url::Url;
-use std::{cmp::{max, min}, future::Future, hash::{BuildHasherDefault, DefaultHasher}, iter::Peekable, ops::{Deref, Not}, path:: Path, sync::{Arc, LazyLock, Mutex}, time::Duration};
+use std::{cmp::{max, min}, future::Future, iter::Peekable, ops::{Deref, Not}, path:: Path, sync::{Arc, LazyLock, Mutex}, time::Duration};
 use std::io;
 use hashbrown::{HashMap, HashSet};
 use crate::{
@@ -1929,12 +1929,9 @@ impl Drop for JoinedRoomDetails {
 }
 
 
-/// A const-compatible hasher, used for `static` items containing `HashMap`s or `HashSet`s.
-type ConstHasher = BuildHasherDefault<DefaultHasher>;
-
 /// Information about all joined rooms that our client currently know about.
 /// We use a `HashMap` for O(1) lookups, as this is accessed frequently (e.g. every timeline update).
-static ALL_JOINED_ROOMS: Mutex<HashMap<OwnedRoomId, JoinedRoomDetails, ConstHasher>> = Mutex::new(HashMap::with_hasher(BuildHasherDefault::new()));
+static ALL_JOINED_ROOMS: LazyLock<Mutex<HashMap<OwnedRoomId, JoinedRoomDetails>>> = LazyLock::new(|| Mutex::new(HashMap::new()));
 
 /// The logged-in Matrix client, which can be freely and cheaply cloned.
 static CLIENT: Mutex<Option<Client>> = Mutex::new(None);
@@ -1962,10 +1959,10 @@ pub fn get_sync_service() -> Option<Arc<SyncService>> {
 /// The list of users that the current user has chosen to ignore.
 /// Ideally we shouldn't have to maintain this list ourselves,
 /// but the Matrix SDK doesn't currently properly maintain the list of ignored users.
-static IGNORED_USERS: Mutex<HashSet<OwnedUserId, ConstHasher>> = Mutex::new(HashSet::with_hasher(BuildHasherDefault::new()));
+static IGNORED_USERS: LazyLock<Mutex<HashSet<OwnedUserId>>> = LazyLock::new(|| Mutex::new(HashSet::new()));
 
 /// Returns a deep clone of the current list of ignored users.
-pub fn get_ignored_users() -> HashSet<OwnedUserId, ConstHasher> {
+pub fn get_ignored_users() -> HashSet<OwnedUserId> {
     IGNORED_USERS.lock().unwrap().clone()
 }
 
@@ -2952,7 +2949,7 @@ fn handle_ignore_user_list_subscriber(client: Client) {
             let ignored_users_new = ignore_list
                 .into_iter()
                 .filter_map(|u| OwnedUserId::try_from(u).ok())
-                .collect::<HashSet<_, ConstHasher>>();
+                .collect::<HashSet<_>>();
 
             // TODO: when we support persistent state, don't forget to update `IGNORED_USERS` upon app boot.
             let mut ignored_users_old = IGNORED_USERS.lock().unwrap();