snapshot of https://github.com/RocketChat/Rocket.Chat.git (develop, 2026-09-16; blobs > 131072B omitted)

apps/meteor/client/views/root/hooks/loggedIn/useUnread.ts

@@ -0,0 +1,69 @@
+import { manageFavicon } from '@rocket.chat/favicon';
+import { useSession, useSessionDispatch, useUserPreference, useUserSubscriptions } from '@rocket.chat/ui-contexts';
+import { useEffect, useRef } from 'react';
+
+import { useFireGlobalEvent } from '../../../../hooks/useFireGlobalEvent';
+
+const query = { open: { $ne: false }, hideUnreadStatus: { $ne: true }, archived: { $ne: true } };
+const options = { fields: { unread: 1, alert: 1, rid: 1, t: 1, name: 1, ls: 1, unreadAlert: 1, fname: 1, prid: 1 } };
+const updateFavicon = manageFavicon();
+
+type UnreadData = { unread: number; alert: boolean | undefined; unreadAlert: string | undefined };
+
+export const useUnread = () => {
+	const unreadAlertEnabled = useUserPreference('unreadAlert');
+	const setUnread = useSessionDispatch('unread');
+	const unread = useSession('unread') as string | number | null | undefined;
+
+	const { mutate: fireEventUnreadChangedBySubscription } = useFireGlobalEvent('unread-changed-by-subscription');
+	const { mutate: fireEventUnreadChanged } = useFireGlobalEvent('unread-changed');
+
+	const subscriptions = useUserSubscriptions(query, options);
+
+	// We keep a lightweight snapshot of the last emitted per-subscription unread state so we only
+	// fire "unread-changed-by-subscription" for subscriptions whose unread-relevant fields changed.
+	// Previously we emitted one global event per subscription on ANY change, which scaled O(N)
+	// with the user subscription count (thousands) for every single message event, dominating CPU.
+	const prevSubsRef = useRef(new Map<string, UnreadData>());
+
+	useEffect(() => {
+		let badgeIndicator: false | '•' = false;
+		let unreadCount = 0;
+		const nextSnapshot = new Map<string, UnreadData>();
+
+		for (const subscription of subscriptions) {
+			const { rid, unread: unreadValue, alert, unreadAlert: subscriptionUnreadAlert } = subscription;
+			const prev = prevSubsRef.current.get(rid);
+			// Emit per-sub event only if something that influences unread UI changed.
+			if (!prev || prev.unread !== unreadValue || prev.alert !== alert || prev.unreadAlert !== subscriptionUnreadAlert) {
+				fireEventUnreadChangedBySubscription(subscription);
+			}
+			nextSnapshot.set(rid, { unread: unreadValue, alert, unreadAlert: subscriptionUnreadAlert });
+
+			if (alert || unreadValue > 0) {
+				if (alert === true && subscriptionUnreadAlert !== 'nothing') {
+					if (subscriptionUnreadAlert === 'all' || unreadAlertEnabled !== false) {
+						badgeIndicator = '•';
+					}
+				}
+				unreadCount += unreadValue;
+			}
+		}
+
+		prevSubsRef.current = nextSnapshot; // swap snapshot
+
+		if (unreadCount > 0) {
+			setUnread(unreadCount > 999 ? '999+' : unreadCount);
+		} else if (badgeIndicator !== false) {
+			setUnread(badgeIndicator);
+		} else {
+			setUnread('');
+		}
+
+		fireEventUnreadChanged(unreadCount);
+	}, [setUnread, subscriptions, unreadAlertEnabled, fireEventUnreadChangedBySubscription, fireEventUnreadChanged]);
+
+	useEffect(() => {
+		updateFavicon(unread);
+	}, [unread]);
+};