Dedupe room list store updates by marking for updates

The core of this is in the MarkedExecution class, with the remainder of the commit ensuring that the right marks and triggers are in place to do the firing.

Because everything is async/await and run through the RoomListStore, we don't have to worry about self-fed updates in the algorithm classes. This also means we have to trigger pretty much all the time. 

Changes to tag ordering / list sorting get hit through two paths, so we mark before we do a bulk update and otherwise assume the call is coming in from outside.

src/stores/room-list/RoomListStore2.ts

@@ -33,6 +33,7 @@ import { EffectiveMembership, getEffectiveMembership } from "./membership";
 import { ListLayout } from "./ListLayout";
 import { isNullOrUndefined } from "matrix-js-sdk/src/utils";
 import RoomListLayoutStore from "./RoomListLayoutStore";
+import { MarkedExecution } from "../../utils/MarkedExecution";
 
 interface IState {
     tagsEnabled?: boolean;
@@ -51,7 +52,7 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
     private algorithm = new Algorithm();
     private filterConditions: IFilterCondition[] = [];
     private tagWatcher = new TagWatcher(this);
-    private layoutMap: Map<TagID, ListLayout> = new Map<TagID, ListLayout>();
+    private updateFn = new MarkedExecution(() => this.emit(LISTS_UPDATE_EVENT));
 
     private readonly watchedSettings = [
         'feature_custom_tags',
@@ -91,24 +92,26 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
         await this.updateAlgorithmInstances();
     }
 
-    private onRVSUpdate = () => {
+    private onRVSUpdate = async (quiet = false) => {
         if (!this.enabled) return; // TODO: Remove with https://github.com/vector-im/riot-web/issues/14231
         if (!this.matrixClient) return; // We assume there won't be RVS updates without a client
 
         const activeRoomId = RoomViewStore.getRoomId();
         if (!activeRoomId && this.algorithm.stickyRoom) {
-            this.algorithm.stickyRoom = null;
+            await this.algorithm.setStickyRoom(null);
         } else if (activeRoomId) {
             const activeRoom = this.matrixClient.getRoom(activeRoomId);
             if (!activeRoom) {
                 console.warn(`${activeRoomId} is current in RVS but missing from client - clearing sticky room`);
-                this.algorithm.stickyRoom = null;
+                await this.algorithm.setStickyRoom(null);
             } else if (activeRoom !== this.algorithm.stickyRoom) {
                 // TODO: Remove debug: https://github.com/vector-im/riot-web/issues/14035
                 console.log(`Changing sticky room to ${activeRoomId}`);
-                this.algorithm.stickyRoom = activeRoom;
+                await this.algorithm.setStickyRoom(activeRoom);
             }
         }
+
+        if (!quiet) this.updateFn.trigger();
     };
 
     protected async onDispatch(payload: ActionPayload) {
@@ -127,8 +130,12 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
             // Update any settings here, as some may have happened before we were logically ready.
             console.log("Regenerating room lists: Startup");
             await this.readAndCacheSettingsFromStore();
-            await this.regenerateAllLists();
+            await this.regenerateAllLists(true);
-            this.onRVSUpdate(); // fake an RVS update to adjust sticky room, if needed
+            await this.onRVSUpdate(true); // fake an RVS update to adjust sticky room, if needed
+
+            this.updateFn.trigger();
+
+            return; // no point in running the next conditions - they won't match
         }
 
         // TODO: Remove this once the RoomListStore becomes default
@@ -137,7 +144,7 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
         if (payload.action === 'on_client_not_viable' || payload.action === 'on_logged_out') {
             // Reset state without causing updates as the client will have been destroyed
             // and downstream code will throw NPE errors.
-            this.reset(null, true);
+            await this.reset(null, true);
             this._matrixClient = null;
             this.initialListsGenerated = false; // we'll want to regenerate them
         }
@@ -151,7 +158,8 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
                 console.log("Regenerating room lists: Settings changed");
                 await this.readAndCacheSettingsFromStore();
 
-                await this.regenerateAllLists(); // regenerate the lists now
+                await this.regenerateAllLists(true); // regenerate the lists now
+                this.updateFn.trigger();
             }
         }
 
@@ -172,6 +180,7 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
                 // TODO: Remove debug: https://github.com/vector-im/riot-web/issues/14035
                 console.log(`[RoomListDebug] Got own read receipt in ${room.roomId}`);
                 await this.handleRoomUpdate(room, RoomUpdateCause.ReadReceipt);
+                this.updateFn.trigger();
                 return;
             }
         } else if (payload.action === 'MatrixActions.Room.tags') {
@@ -179,6 +188,7 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
             // TODO: Remove debug: https://github.com/vector-im/riot-web/issues/14035
             console.log(`[RoomListDebug] Got tag change in ${roomPayload.room.roomId}`);
             await this.handleRoomUpdate(roomPayload.room, RoomUpdateCause.PossibleTagChange);
+            this.updateFn.trigger();
         } else if (payload.action === 'MatrixActions.Room.timeline') {
             const eventPayload = (<any>payload); // TODO: Type out the dispatcher types
 
@@ -202,6 +212,7 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
                     }
                 }
                 await this.handleRoomUpdate(updatedRoom, RoomUpdateCause.Timeline);
+                this.updateFn.trigger();
             };
             if (!room) {
                 console.warn(`Live timeline event ${eventPayload.event.getId()} received without associated room`);
@@ -225,6 +236,7 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
             // TODO: Remove debug: https://github.com/vector-im/riot-web/issues/14035
             console.log(`[RoomListDebug] Decrypted timeline event ${eventPayload.event.getId()} in ${roomId}`);
             await this.handleRoomUpdate(room, RoomUpdateCause.Timeline);
+            this.updateFn.trigger();
         } else if (payload.action === 'MatrixActions.accountData' && payload.event_type === 'm.direct') {
             const eventPayload = (<any>payload); // TODO: Type out the dispatcher types
             // TODO: Remove debug: https://github.com/vector-im/riot-web/issues/14035
@@ -246,6 +258,7 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
                     await this.handleRoomUpdate(room, RoomUpdateCause.PossibleTagChange);
                 }
             }
+            this.updateFn.trigger();
         } else if (payload.action === 'MatrixActions.Room.myMembership') {
             const membershipPayload = (<any>payload); // TODO: Type out the dispatcher types
             const oldMembership = getEffectiveMembership(membershipPayload.oldMembership);
@@ -264,7 +277,7 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
                         const isSticky = this.algorithm.stickyRoom === prevRoom;
                         if (isSticky) {
                             console.log(`[RoomListDebug] Clearing sticky room due to room upgrade`);
-                            await this.algorithm.setStickyRoomAsync(null);
+                            await this.algorithm.setStickyRoom(null);
                         }
 
                         // Note: we hit the algorithm instead of our handleRoomUpdate() function to
@@ -276,6 +289,7 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
 
                 console.log(`[RoomListDebug] Adding new room to room list`);
                 await this.handleRoomUpdate(membershipPayload.room, RoomUpdateCause.NewRoom);
+                this.updateFn.trigger();
                 return;
             }
 
@@ -283,6 +297,7 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
                 // TODO: Remove debug: https://github.com/vector-im/riot-web/issues/14035
                 console.log(`[RoomListDebug] Handling invite to ${membershipPayload.room.roomId}`);
                 await this.handleRoomUpdate(membershipPayload.room, RoomUpdateCause.NewRoom);
+                this.updateFn.trigger();
                 return;
             }
 
@@ -291,6 +306,7 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
                 // TODO: Remove debug: https://github.com/vector-im/riot-web/issues/14035
                 console.log(`[RoomListDebug] Handling membership change in ${membershipPayload.room.roomId}`);
                 await this.handleRoomUpdate(membershipPayload.room, RoomUpdateCause.PossibleTagChange);
+                this.updateFn.trigger();
                 return;
             }
         }
@@ -301,7 +317,7 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
         if (shouldUpdate) {
             // TODO: Remove debug: https://github.com/vector-im/riot-web/issues/14035
             console.log(`[DEBUG] Room "${room.name}" (${room.roomId}) triggered by ${cause} requires list update`);
-            this.emit(LISTS_UPDATE_EVENT, this);
+            this.updateFn.mark();
         }
     }
 
@@ -309,6 +325,7 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
         await this.algorithm.setTagSorting(tagId, sort);
         // TODO: Per-account? https://github.com/vector-im/riot-web/issues/14114
         localStorage.setItem(`mx_tagSort_${tagId}`, sort);
+        this.updateFn.triggerIfWillMark();
     }
 
     public getTagSorting(tagId: TagID): SortAlgorithm {
@@ -347,6 +364,7 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
         await this.algorithm.setListOrdering(tagId, order);
         // TODO: Per-account? https://github.com/vector-im/riot-web/issues/14114
         localStorage.setItem(`mx_listOrder_${tagId}`, order);
+        this.updateFn.triggerIfWillMark();
     }
 
     public getListOrder(tagId: TagID): ListAlgorithm {
@@ -382,6 +400,10 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
     }
 
     private async updateAlgorithmInstances() {
+        // We'll require an update, so mark for one. Marking now also prevents the calls
+        // to setTagSorting and setListOrder from causing triggers.
+        this.updateFn.mark();
+
         for (const tag of Object.keys(this.orderedLists)) {
             const definedSort = this.getTagSorting(tag);
             const definedOrder = this.getListOrder(tag);
@@ -406,11 +428,11 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
 
     private onAlgorithmListUpdated = () => {
         // TODO: Remove debug: https://github.com/vector-im/riot-web/issues/14035
-        console.log("Underlying algorithm has triggered a list update - refiring");
+        console.log("Underlying algorithm has triggered a list update - marking");
-        this.emit(LISTS_UPDATE_EVENT, this);
+        this.updateFn.mark();
     };
 
-    private async regenerateAllLists() {
+    private async regenerateAllLists(quiet = false) {
         console.warn("Regenerating all room lists");
 
         const sorts: ITagSortingMap = {};
@@ -435,7 +457,7 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
 
         this.initialListsGenerated = true;
 
-        this.emit(LISTS_UPDATE_EVENT, this);
+        if (!quiet) this.updateFn.trigger();
     }
 
     public addFilter(filter: IFilterCondition): void {
@@ -445,6 +467,7 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
         if (this.algorithm) {
             this.algorithm.addFilterCondition(filter);
         }
+        this.updateFn.trigger();
     }
 
     public removeFilter(filter: IFilterCondition): void {
@@ -458,6 +481,7 @@ export class RoomListStore2 extends AsyncStore<ActionPayload> {
                 this.algorithm.removeFilterCondition(filter);
             }
         }
+        this.updateFn.trigger();
     }
 
     /**

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

@@ -87,12 +87,6 @@ export class Algorithm extends EventEmitter {
         return this._stickyRoom ? this._stickyRoom.room : null;
     }
 
-    public set stickyRoom(val: Room) {
-        // setters can't be async, so we call a private function to do the work
-        // noinspection JSIgnoredPromiseFromCall
-        this.updateStickyRoom(val);
-    }
-
     protected get hasFilters(): boolean {
         return this.allowedByFilter.size > 0;
     }
@@ -115,7 +109,7 @@ export class Algorithm extends EventEmitter {
      * Awaitable version of the sticky room setter.
      * @param val The new room to sticky.
      */
-    public async setStickyRoomAsync(val: Room) {
+    public async setStickyRoom(val: Room) {
         await this.updateStickyRoom(val);
     }
 
@@ -746,7 +740,7 @@ export class Algorithm extends EventEmitter {
                     };
                 } else {
                     // We have to clear the lock as the sticky room change will trigger updates.
-                    await this.setStickyRoomAsync(room);
+                    await this.setStickyRoom(room);
                 }
             }
         }

src/utils/MarkedExecution.ts

@@ -0,0 +1,67 @@
+/*
+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.
+*/
+
+/**
+ * A utility to ensure that a function is only called once triggered with
+ * a mark applied. Multiple marks can be applied to the function, however
+ * the function will only be called once upon trigger().
+ *
+ * The function starts unmarked.
+ */
+export class MarkedExecution {
+    private marked = false;
+
+    /**
+     * Creates a MarkedExecution for the provided function.
+     * @param fn The function to be called upon trigger if marked.
+     */
+    constructor(private fn: () => void) {
+    }
+
+    /**
+     * Resets the mark without calling the function.
+     */
+    public reset() {
+        this.marked = false;
+    }
+
+    /**
+     * Marks the function to be called upon trigger().
+     */
+    public mark() {
+        this.marked = true;
+    }
+
+    /**
+     * If marked, the function will be called, otherwise this does nothing.
+     */
+    public trigger() {
+        if (!this.marked) return;
+        this.fn();
+        this.reset();
+    }
+
+    /**
+     * Triggers the function if a mark() call would mark it. If the function
+     * has already been marked this will do nothing.
+     */
+    public triggerIfWillMark() {
+        if (!this.marked) {
+            this.mark();
+            this.trigger();
+        }
+    }
+}