emit aggregate room beacon liveness (#2241)

* emit aggregate room beacon liveness

Signed-off-by: Kerry Archibald <kerrya@element.io>

* tidy and comment

Signed-off-by: Kerry Archibald <kerrya@element.io>

* add export for models/beacon

Signed-off-by: Kerry Archibald <kerrya@element.io>

* add owner and roomId

Signed-off-by: Kerry Archibald <kerrya@element.io>

* copyright

Signed-off-by: Kerry Archibald <kerrya@element.io>

spec/test-utils/emitter.ts

@@ -0,0 +1,28 @@
+/*
+Copyright 2022 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.
+*/
+
+/**
+ * Filter emitter.emit mock calls to find relevant events
+ * eg:
+ * ```
+ * const emitSpy = jest.spyOn(state, 'emit');
+ * << actions >>
+ * const beaconLivenessEmits = emitCallsByEventType(BeaconEvent.New, emitSpy);
+ * expect(beaconLivenessEmits.length).toBe(1);
+ * ```
+ */
+export const filterEmitCallsByEventType = (eventType: string, spy: jest.SpyInstance<any, unknown[]>) =>
+    spy.mock.calls.filter((args) => args[0] === eventType);

spec/unit/models/beacon.spec.ts

@@ -24,6 +24,8 @@ import {
 } from "../../../src/models/beacon";
 import { makeBeaconInfoEvent } from "../../test-utils/beacon";
 
+jest.useFakeTimers();
+
 describe('Beacon', () => {
     describe('isTimestampInDuration()', () => {
         const startTs = new Date('2022-03-11T12:07:47.592Z').getTime();
@@ -86,6 +88,14 @@ describe('Beacon', () => {
         // without timeout of 3 hours
         let liveBeaconEvent;
         let notLiveBeaconEvent;
+
+        const advanceDateAndTime = (ms: number) => {
+            // bc liveness check uses Date.now we have to advance this mock
+            jest.spyOn(global.Date, 'now').mockReturnValue(now + ms);
+            // then advance time for the interval by the same amount
+            jest.advanceTimersByTime(ms);
+        };
+
         beforeEach(() => {
             // go back in time to create the beacon
             jest.spyOn(global.Date, 'now').mockReturnValue(now - HOUR_MS);
@@ -109,7 +119,9 @@ describe('Beacon', () => {
             const beacon = new Beacon(liveBeaconEvent);
 
             expect(beacon.beaconInfoId).toEqual(liveBeaconEvent.getId());
+            expect(beacon.roomId).toEqual(roomId);
             expect(beacon.isLive).toEqual(true);
+            expect(beacon.beaconInfoOwner).toEqual(userId);
         });
 
         describe('isLive()', () => {
@@ -163,6 +175,69 @@ describe('Beacon', () => {
                 expect(beacon.isLive).toEqual(false);
                 expect(emitSpy).toHaveBeenCalledWith(BeaconEvent.Update, updatedBeaconEvent, beacon);
             });
+
+            it('emits livenesschange event when beacon liveness changes', () => {
+                const beacon = new Beacon(liveBeaconEvent);
+                const emitSpy = jest.spyOn(beacon, 'emit');
+
+                expect(beacon.isLive).toEqual(true);
+
+                const updatedBeaconEvent = makeBeaconInfoEvent(
+                    userId, roomId, { timeout: HOUR_MS * 3, isLive: false }, beacon.beaconInfoId);
+
+                beacon.update(updatedBeaconEvent);
+                expect(beacon.isLive).toEqual(false);
+                expect(emitSpy).toHaveBeenCalledWith(BeaconEvent.LivenessChange, false, beacon);
+            });
+        });
+
+        describe('monitorLiveness()', () => {
+            it('does not set a monitor interval when beacon is not live', () => {
+                // beacon was created an hour ago
+                // and has a 3hr duration
+                const beacon = new Beacon(notLiveBeaconEvent);
+                const emitSpy = jest.spyOn(beacon, 'emit');
+
+                beacon.monitorLiveness();
+
+                // @ts-ignore
+                expect(beacon.livenessWatchInterval).toBeFalsy();
+                advanceDateAndTime(HOUR_MS * 2 + 1);
+
+                // no emit
+                expect(emitSpy).not.toHaveBeenCalled();
+            });
+
+            it('checks liveness of beacon at expected expiry time', () => {
+                // live beacon was created an hour ago
+                // and has a 3hr duration
+                const beacon = new Beacon(liveBeaconEvent);
+                expect(beacon.isLive).toBeTruthy();
+                const emitSpy = jest.spyOn(beacon, 'emit');
+
+                beacon.monitorLiveness();
+                advanceDateAndTime(HOUR_MS * 2 + 1);
+
+                expect(emitSpy).toHaveBeenCalledTimes(1);
+                expect(emitSpy).toHaveBeenCalledWith(BeaconEvent.LivenessChange, false, beacon);
+            });
+
+            it('destroy kills liveness monitor', () => {
+                // live beacon was created an hour ago
+                // and has a 3hr duration
+                const beacon = new Beacon(liveBeaconEvent);
+                expect(beacon.isLive).toBeTruthy();
+                const emitSpy = jest.spyOn(beacon, 'emit');
+
+                beacon.monitorLiveness();
+
+                // destroy the beacon
+                beacon.destroy();
+
+                advanceDateAndTime(HOUR_MS * 2 + 1);
+
+                expect(emitSpy).not.toHaveBeenCalled();
+            });
         });
     });
 });

spec/unit/room-state.spec.js

@@ -1,6 +1,7 @@
 import * as utils from "../test-utils/test-utils";
 import { makeBeaconInfoEvent } from "../test-utils/beacon";
-import { RoomState } from "../../src/models/room-state";
+import { filterEmitCallsByEventType } from "../test-utils/emitter";
+import { RoomState, RoomStateEvent } from "../../src/models/room-state";
 
 describe("RoomState", function() {
     const roomId = "!foo:bar";
@@ -275,6 +276,29 @@ describe("RoomState", function() {
             // updated liveness
             expect(state.beacons.get(beaconId).isLive).toEqual(false);
         });
+
+        it('updates live beacon ids once after setting state events', () => {
+            const liveBeaconEvent = makeBeaconInfoEvent(userA, roomId, { isLive: true }, '$beacon1');
+            const deadBeaconEvent = makeBeaconInfoEvent(userA, roomId, { isLive: false }, '$beacon2');
+
+            const emitSpy = jest.spyOn(state, 'emit');
+
+            state.setStateEvents([liveBeaconEvent, deadBeaconEvent]);
+
+            // called once
+            expect(filterEmitCallsByEventType(RoomStateEvent.BeaconLiveness, emitSpy).length).toBe(1);
+
+            // live beacon is now not live
+            const updatedLiveBeaconEvent = makeBeaconInfoEvent(
+                userA, roomId, { isLive: false }, liveBeaconEvent.getId(),
+            );
+
+            state.setStateEvents([updatedLiveBeaconEvent]);
+
+            expect(state.hasLiveBeacons).toBe(false);
+            expect(filterEmitCallsByEventType(RoomStateEvent.BeaconLiveness, emitSpy).length).toBe(2);
+            expect(emitSpy).toHaveBeenCalledWith(RoomStateEvent.BeaconLiveness, state, false);
+        });
     });
 
     describe("setOutOfBandMembers", function() {

src/matrix.ts

@@ -27,6 +27,7 @@ export * from "./http-api";
 export * from "./autodiscovery";
 export * from "./sync-accumulator";
 export * from "./errors";
+export * from "./models/beacon";
 export * from "./models/event";
 export * from "./models/room";
 export * from "./models/group";

src/models/beacon.ts

@@ -22,12 +22,14 @@ import { TypedEventEmitter } from "./typed-event-emitter";
 export enum BeaconEvent {
     New = "Beacon.new",
     Update = "Beacon.update",
+    LivenessChange = "Beacon.LivenessChange",
 }
 
-type EmittedEvents = BeaconEvent.New | BeaconEvent.Update;
+type EmittedEvents = BeaconEvent;
 type EventHandlerMap = {
     [BeaconEvent.New]: (event: MatrixEvent, beacon: Beacon) => void;
     [BeaconEvent.Update]: (event: MatrixEvent, beacon: Beacon) => void;
+    [BeaconEvent.LivenessChange]: (isLive: boolean, beacon: Beacon) => void;
 };
 
 export const isTimestampInDuration = (
@@ -42,32 +44,77 @@ export const isBeaconInfoEventType = (type: string) =>
 
 // https://github.com/matrix-org/matrix-spec-proposals/pull/3489
 export class Beacon extends TypedEventEmitter<EmittedEvents, EventHandlerMap> {
+    public readonly roomId: string;
     private beaconInfo: BeaconInfoState;
+    private _isLive: boolean;
+    private livenessWatchInterval: number;
 
     constructor(
         private rootEvent: MatrixEvent,
     ) {
         super();
-        this.beaconInfo = parseBeaconInfoContent(this.rootEvent.getContent());
+        this.setBeaconInfo(this.rootEvent);
+        this.roomId = this.rootEvent.getRoomId();
         this.emit(BeaconEvent.New, this.rootEvent, this);
     }
 
     public get isLive(): boolean {
-        return this.beaconInfo?.live &&
-            isTimestampInDuration(this.beaconInfo?.timestamp, this.beaconInfo?.timeout, Date.now());
+        return this._isLive;
     }
 
     public get beaconInfoId(): string {
         return this.rootEvent.getId();
     }
 
+    public get beaconInfoOwner(): string {
+        return this.rootEvent.getStateKey();
+    }
+
     public update(beaconInfoEvent: MatrixEvent): void {
         if (beaconInfoEvent.getId() !== this.beaconInfoId) {
             throw new Error('Invalid updating event');
         }
         this.rootEvent = beaconInfoEvent;
-        this.beaconInfo = parseBeaconInfoContent(this.rootEvent.getContent());
+        this.setBeaconInfo(this.rootEvent);
 
         this.emit(BeaconEvent.Update, beaconInfoEvent, this);
     }
+
+    public destroy(): void {
+        if (this.livenessWatchInterval) {
+            clearInterval(this.livenessWatchInterval);
+        }
+    }
+
+    /**
+     * Monitor liveness of a beacon
+     * Emits BeaconEvent.LivenessChange when beacon expires
+     */
+    public monitorLiveness(): void {
+        if (this.livenessWatchInterval) {
+            clearInterval(this.livenessWatchInterval);
+        }
+
+        if (this.isLive) {
+            const expiryInMs = (this.beaconInfo?.timestamp + this.beaconInfo?.timeout + 1) - Date.now();
+            if (expiryInMs > 1) {
+                this.livenessWatchInterval = setInterval(this.checkLiveness.bind(this), expiryInMs);
+            }
+        }
+    }
+
+    private setBeaconInfo(event: MatrixEvent): void {
+        this.beaconInfo = parseBeaconInfoContent(event.getContent());
+        this.checkLiveness();
+    }
+
+    private checkLiveness(): void {
+        const prevLiveness = this.isLive;
+        this._isLive = this.beaconInfo?.live &&
+            isTimestampInDuration(this.beaconInfo?.timestamp, this.beaconInfo?.timeout, Date.now());
+
+        if (prevLiveness !== this.isLive) {
+            this.emit(BeaconEvent.LivenessChange, this.isLive, this);
+        }
+    }
 }

src/models/room-state.ts

@@ -26,7 +26,7 @@ import { MatrixEvent } from "./event";
 import { MatrixClient } from "../client";
 import { GuestAccess, HistoryVisibility, IJoinRuleEventContent, JoinRule } from "../@types/partials";
 import { TypedEventEmitter } from "./typed-event-emitter";
-import { Beacon, isBeaconInfoEventType } from "./beacon";
+import { Beacon, BeaconEvent, isBeaconInfoEventType } from "./beacon";
 
 // possible statuses for out-of-band member loading
 enum OobStatus {
@@ -40,6 +40,7 @@ export enum RoomStateEvent {
     Members = "RoomState.members",
     NewMember = "RoomState.newMember",
     Update = "RoomState.update", // signals batches of updates without specificity
+    BeaconLiveness = "RoomState.BeaconLiveness",
 }
 
 export type RoomStateEventHandlerMap = {
@@ -47,6 +48,7 @@ export type RoomStateEventHandlerMap = {
     [RoomStateEvent.Members]: (event: MatrixEvent, state: RoomState, member: RoomMember) => void;
     [RoomStateEvent.NewMember]: (event: MatrixEvent, state: RoomState, member: RoomMember) => void;
     [RoomStateEvent.Update]: (state: RoomState) => void;
+    [RoomStateEvent.BeaconLiveness]: (state: RoomState, hasLiveBeacons: boolean) => void;
 };
 
 export class RoomState extends TypedEventEmitter<RoomStateEvent, RoomStateEventHandlerMap> {
@@ -73,6 +75,7 @@ export class RoomState extends TypedEventEmitter<RoomStateEvent, RoomStateEventH
     public paginationToken: string = null;
 
     public readonly beacons = new Map<string, Beacon>();
+    private liveBeaconIds: string[] = [];
 
     /**
      * Construct room state.
@@ -235,6 +238,10 @@ export class RoomState extends TypedEventEmitter<RoomStateEvent, RoomStateEventH
         return event ? event : null;
     }
 
+    public get hasLiveBeacons(): boolean {
+        return !!this.liveBeaconIds?.length;
+    }
+
     /**
      * Creates a copy of this room state so that mutations to either won't affect the other.
      * @return {RoomState} the copy of the room state
@@ -330,6 +337,8 @@ export class RoomState extends TypedEventEmitter<RoomStateEvent, RoomStateEventH
             this.emit(RoomStateEvent.Events, event, this, lastStateEvent);
         });
 
+        this.onBeaconLivenessChange();
+
         // update higher level data structures. This needs to be done AFTER the
         // core event dict as these structures may depend on other state events in
         // the given array (e.g. disambiguating display names in one go to do both
@@ -418,15 +427,37 @@ export class RoomState extends TypedEventEmitter<RoomStateEvent, RoomStateEventH
         this.events.get(event.getType()).set(event.getStateKey(), event);
     }
 
+    /**
+     * @experimental
+     */
     private setBeacon(event: MatrixEvent): void {
         if (this.beacons.has(event.getId())) {
             return this.beacons.get(event.getId()).update(event);
         }
 
         const beacon = new Beacon(event);
+        beacon.on(BeaconEvent.LivenessChange, this.onBeaconLivenessChange.bind(this));
         this.beacons.set(beacon.beaconInfoId, beacon);
     }
 
+    /**
+     * @experimental
+     * Check liveness of room beacons
+     * emit RoomStateEvent.BeaconLiveness when
+     * roomstate.hasLiveBeacons has changed
+     */
+    private onBeaconLivenessChange(): void {
+        const prevHasLiveBeacons = !!this.liveBeaconIds?.length;
+        this.liveBeaconIds = Array.from(this.beacons.values())
+            .filter(beacon => beacon.isLive)
+            .map(beacon => beacon.beaconInfoId);
+
+        const hasLiveBeacons = !!this.liveBeaconIds.length;
+        if (prevHasLiveBeacons !== hasLiveBeacons) {
+            this.emit(RoomStateEvent.BeaconLiveness, this, hasLiveBeacons);
+        }
+    }
+
     private getStateEventMatching(event: MatrixEvent): MatrixEvent | null {
         return this.events.get(event.getType())?.get(event.getStateKey()) ?? null;
     }