Wrap handleRoomUpdate in a lock

Dev note: this is removed in a later commit

src/stores/room-list/algorithms/Algorithm.ts

@@ -33,6 +33,7 @@ import { FILTER_CHANGED, FilterPriority, IFilterCondition } from "../filters/IFi
 import { EffectiveMembership, getEffectiveMembership, splitRoomsByMembership } from "../membership";
 import { OrderingAlgorithm } from "./list-ordering/OrderingAlgorithm";
 import { getListAlgorithmInstance } from "./list-ordering";
+import AwaitLock from "await-lock";
 
 // TODO: Add locking support to avoid concurrent writes? https://github.com/vector-im/riot-web/issues/14235
 
@@ -66,6 +67,7 @@ export class Algorithm extends EventEmitter {
     } = {};
     private allowedByFilter: Map<IFilterCondition, Room[]> = new Map<IFilterCondition, Room[]>();
     private allowedRoomsByFilters: Set<Room> = new Set<Room>();
+    private readonly lock = new AwaitLock();
 
     public constructor() {
         super();
@@ -607,6 +609,9 @@ export class Algorithm extends EventEmitter {
      * processing.
      */
     public async handleRoomUpdate(room: Room, cause: RoomUpdateCause): Promise<boolean> {
+        try {
+            await this.lock.acquireAsync();
+
             if (!this.algorithms) throw new Error("Not ready: no algorithms to determine tags from");
 
             if (cause === RoomUpdateCause.NewRoom) {
@@ -669,5 +674,8 @@ export class Algorithm extends EventEmitter {
             }
 
             return true;
+        } finally {
+            this.lock.release();
+        }
     }
 }