Replace countRoomsWithNotif with a dedicated NotificationState

Fixes https://github.com/vector-im/riot-web/issues/14694

Instead of spending 10-1000ms in a function iterating over a whole lot of room events, we can use our cached state from the Notification State Store. 

This commit sets up a structure that could be applied to communities in the TagPanel too, as that could probably use a similar optimization.

This reduces the updateStatusIndicator() time to just 4ms on average.

src/RoomNotifs.js

@@ -34,27 +34,6 @@ export function shouldShowMentionBadge(roomNotifState) {
     return MENTION_BADGE_STATES.includes(roomNotifState);
 }
 
-export function countRoomsWithNotif(rooms) {
-    return rooms.reduce((result, room, index) => {
-        const roomNotifState = getRoomNotifsState(room.roomId);
-        const highlight = room.getUnreadNotificationCount('highlight') > 0;
-        const notificationCount = room.getUnreadNotificationCount();
-
-        const notifBadges = notificationCount > 0 && shouldShowNotifBadge(roomNotifState);
-        const mentionBadges = highlight && shouldShowMentionBadge(roomNotifState);
-        const isInvite = room.hasMembershipState(MatrixClientPeg.get().credentials.userId, 'invite');
-        const badges = notifBadges || mentionBadges || isInvite;
-
-        if (badges) {
-            result.count++;
-            if (highlight) {
-                result.highlight = true;
-            }
-        }
-        return result;
-    }, {count: 0, highlight: false});
-}
-
 export function aggregateNotificationCount(rooms) {
     return rooms.reduce((result, room) => {
         const roomNotifState = getRoomNotifsState(room.roomId);

src/components/structures/MatrixChat.tsx

@@ -58,7 +58,6 @@ import { messageForSyncError } from '../../utils/ErrorUtils';
 import ResizeNotifier from "../../utils/ResizeNotifier";
 import AutoDiscoveryUtils, { ValidatedServerConfig } from "../../utils/AutoDiscoveryUtils";
 import DMRoomMap from '../../utils/DMRoomMap';
-import { countRoomsWithNotif } from '../../RoomNotifs';
 import ThemeWatcher from "../../settings/watchers/ThemeWatcher";
 import { FontWatcher } from '../../settings/watchers/FontWatcher';
 import { storeRoomAliasInCache } from '../../RoomAliasCache';
@@ -75,6 +74,7 @@ import {
 import {showToast as showNotificationsToast} from "../../toasts/DesktopNotificationsToast";
 import { OpenToTabPayload } from "../../dispatcher/payloads/OpenToTabPayload";
 import ErrorDialog from "../views/dialogs/ErrorDialog";
+import { RoomNotificationStateStore } from "../../stores/notifications/RoomNotificationStateStore";
 
 /** constants for MatrixChat.state.view */
 export enum Views {
@@ -1844,21 +1844,20 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
     }
 
     updateStatusIndicator(state: string, prevState: string) {
-        // only count visible rooms to not torment the user with notification counts in rooms they can't see
-        // it will include highlights from the previous version of the room internally
-        const notifCount = countRoomsWithNotif(MatrixClientPeg.get().getVisibleRooms()).count;
+        const notificationState = RoomNotificationStateStore.instance.globalState;
+        const numUnreadRooms = notificationState.numUnreadStates; // we know that states === rooms here
 
         if (PlatformPeg.get()) {
             PlatformPeg.get().setErrorStatus(state === 'ERROR');
-            PlatformPeg.get().setNotificationCount(notifCount);
+            PlatformPeg.get().setNotificationCount(numUnreadRooms);
         }
 
         this.subTitleStatus = '';
         if (state === "ERROR") {
             this.subTitleStatus += `[${_t("Offline")}] `;
         }
-        if (notifCount > 0) {
-            this.subTitleStatus += `[${notifCount}]`;
+        if (numUnreadRooms > 0) {
+            this.subTitleStatus += `[${numUnreadRooms}]`;
         }
 
         this.setPageSubtitle();

src/stores/notifications/RoomNotificationStateStore.ts

@@ -21,6 +21,8 @@ import { DefaultTagID, TagID } from "../room-list/models";
 import { FetchRoomFn, ListNotificationState } from "./ListNotificationState";
 import { Room } from "matrix-js-sdk/src/models/room";
 import { RoomNotificationState } from "./RoomNotificationState";
+import { NotificationState } from "./NotificationState";
+import { SummarizedNotificationState } from "./SummarizedNotificationState";
 
 interface IState {}
 
@@ -33,6 +35,23 @@ export class RoomNotificationStateStore extends AsyncStoreWithClient<IState> {
         super(defaultDispatcher, {});
     }
 
+    /**
+     * Gets a snapshot of notification state for all visible rooms. The number of states recorded
+     * on the SummarizedNotificationState is equivalent to rooms.
+     */
+    public get globalState(): SummarizedNotificationState {
+        // If we're not ready yet, just return an empty state
+        if (!this.matrixClient) return new SummarizedNotificationState();
+
+        // Only count visible rooms to not torment the user with notification counts in rooms they can't see.
+        // This will include highlights from the previous version of the room internally
+        const globalState = new SummarizedNotificationState();
+        for (const room of this.matrixClient.getVisibleRooms()) {
+            globalState.add(this.getRoomState(room));
+        }
+        return globalState;
+    }
+
     /**
      * Creates a new list notification state. The consumer is expected to set the rooms
      * on the notification state, and destroy the state when it no longer needs it.

src/stores/notifications/SummarizedNotificationState.ts

@@ -0,0 +1,62 @@
+/*
+Copyright 2020 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import { NotificationColor } from "./NotificationColor";
+import { NotificationState } from "./NotificationState";
+
+/**
+ * Summarizes a number of states into a unique snapshot. To populate, call
+ * the add() function with the notification states to be included.
+ *
+ * Useful for community notification counts, global notification counts, etc.
+ */
+export class SummarizedNotificationState extends NotificationState {
+    private _totalStatesWithUnread = 0;
+
+    constructor() {
+        super();
+        this._symbol = null;
+        this._count = 0;
+        this._color = NotificationColor.None;
+    }
+
+    public get numUnreadStates(): number {
+        return this._totalStatesWithUnread;
+    }
+
+    /**
+     * Append a notification state to this snapshot, taking the loudest NotificationColor
+     * of the two. By default this will not adopt the symbol of the other notification
+     * state to prevent the count from being lost in typical usage.
+     * @param other The other notification state to append.
+     * @param includeSymbol If true, the notification state's symbol will be taken if one
+     * is present.
+     */
+    public add(other: NotificationState, includeSymbol = false) {
+        if (other.symbol && includeSymbol) {
+            this._symbol = other.symbol;
+        }
+        if (other.count) {
+            this._count += other.count;
+        }
+        if (other.color > this.color) {
+            this._color = other.color;
+        }
+        if (other.hasUnreadCount) {
+            this._totalStatesWithUnread++;
+        }
+    }
+}