refactor: Enhance user caching mechanism for publication access with timeout management

Author: ggazzo

apps/meteor/server/modules/streamer/publication-user-cache.ts

@@ -4,37 +4,37 @@ import { Users } from '@rocket.chat/models';
 import type { IPublication } from './types';
 
 const CACHE_PROJECTION = { _id: 1, roles: 1 } as const;
+const CACHE_TIMEOUT = 1000 * 60;
+const cacheByPublication = new Map<string, { user: Pick<IUser, '_id' | 'roles'>; timeout: NodeJS.Timeout }>();
 
-/** Cache keyed by publication so entries can be GC'd when the subscription is gone. */
-const cacheByPublication = new WeakMap<IPublication, { user: IUser | null; userId: string }>();
-
-/** User ids that received watch.users; next get for a publication with that userId will refetch. */
-const invalidatedUserIds = new Set<string>();
-
-export async function getCachedUserForPublication(publication: IPublication): Promise<IUser | null> {
+export async function getCachedUserForPublication(publication: IPublication): Promise<Pick<IUser, '_id' | 'roles'> | null> {
 	const userId = publication.userId ?? publication._session?.userId ?? undefined;
 	if (userId == null || userId === '') {
 		return null;
 	}
 
-	const entry = cacheByPublication.get(publication);
+	const entry = cacheByPublication.get(userId);
+
 	if (entry) {
-		if (invalidatedUserIds.has(entry.userId)) {
-			const user = await Users.findOneById(entry.userId, { projection: CACHE_PROJECTION });
-			const value = user ?? null;
-			cacheByPublication.set(publication, { user: value, userId: entry.userId });
-			invalidatedUserIds.delete(entry.userId);
-			return value;
-		}
+		clearTimeout(entry.timeout);
+		entry.timeout = setTimeout(() => {
+			cacheByPublication.delete(userId);
+		}, CACHE_TIMEOUT);
 		return entry.user;
 	}
 
-	const user = await Users.findOneById(userId, { projection: CACHE_PROJECTION });
+	const user = await Users.findOneById<Pick<IUser, '_id' | 'roles'>>(userId, { projection: CACHE_PROJECTION });
 	const value = user ?? null;
-	cacheByPublication.set(publication, { user: value, userId });
+	if (value) {
+		const timeout = setTimeout(() => {
+			cacheByPublication.delete(userId);
+		}, CACHE_TIMEOUT);
+
+		cacheByPublication.set(userId, { user: value, timeout });
+	}
 	return value;
 }
 
 export function invalidate(userId: string): void {
-	invalidatedUserIds.add(userId);
+	cacheByPublication.delete(userId);
 }