sliding sync: add custom room subscriptions support

spec/integ/sliding-sync.spec.ts

@@ -1112,6 +1112,156 @@ describe("SlidingSync", () => {
         });
     });
 
+    describe("custom room subscriptions", () => {
+        beforeAll(setupClient);
+        afterAll(teardownClient);
+
+        const roomA = "!a";
+        const roomB = "!b";
+        const roomC = "!c";
+        const roomD = "!d";
+
+        const defaultSub = {
+            timeline_limit: 1,
+            required_state: [["m.room.create", ""]],
+        };
+
+        const customSubName1 = "sub1";
+        const customSub1 = {
+            timeline_limit: 2,
+            required_state: [["*", "*"]],
+        };
+
+        const customSubName2 = "sub2";
+        const customSub2 = {
+            timeline_limit: 3,
+            required_state: [["*", "*"]],
+        };
+
+        it("should be possible to use custom subscriptions on startup", async () => {
+            const slidingSync = new SlidingSync(proxyBaseUrl, [], defaultSub, client!, 1);
+            // the intention is for clients to set this up at startup
+            slidingSync.addCustomSubscription(customSubName1, customSub1);
+            slidingSync.addCustomSubscription(customSubName2, customSub2);
+            // then call these depending on the kind of room / context
+            slidingSync.useCustomSubscription(roomA, customSubName1);
+            slidingSync.useCustomSubscription(roomB, customSubName1);
+            slidingSync.useCustomSubscription(roomC, customSubName2);
+            slidingSync.modifyRoomSubscriptions(new Set<string>([roomA, roomB, roomC, roomD]));
+
+            httpBackend!.when("POST", syncUrl).check(function(req) {
+                const body = req.data;
+                logger.log("custom subs", body);
+                expect(body.room_subscriptions).toBeTruthy();
+                expect(body.room_subscriptions[roomA]).toEqual(customSub1);
+                expect(body.room_subscriptions[roomB]).toEqual(customSub1);
+                expect(body.room_subscriptions[roomC]).toEqual(customSub2);
+                expect(body.room_subscriptions[roomD]).toEqual(defaultSub);
+            }).respond(200, {
+                pos: "b",
+                lists: [],
+                extensions: {},
+                rooms: {},
+            });
+            slidingSync.start();
+            await httpBackend!.flushAllExpected();
+            slidingSync.stop();
+        });
+
+        it("should be possible to use custom subscriptions mid-connection", async () => {
+            const slidingSync = new SlidingSync(proxyBaseUrl, [], defaultSub, client!, 1);
+            // the intention is for clients to set this up at startup
+            slidingSync.addCustomSubscription(customSubName1, customSub1);
+            slidingSync.addCustomSubscription(customSubName2, customSub2);
+            // initially no subs
+            httpBackend!.when("POST", syncUrl).check(function(req) {
+                const body = req.data;
+                logger.log("custom subs", body);
+                expect(body.room_subscriptions).toBeFalsy();
+            }).respond(200, {
+                pos: "b",
+                lists: [],
+                extensions: {},
+                rooms: {},
+            });
+            slidingSync.start();
+            await httpBackend!.flushAllExpected();
+
+            // now the user clicks on a room which uses the default sub
+            httpBackend!.when("POST", syncUrl).check(function(req) {
+                const body = req.data;
+                logger.log("custom subs", body);
+                expect(body.room_subscriptions).toBeTruthy();
+                expect(body.room_subscriptions[roomA]).toEqual(defaultSub);
+            }).respond(200, {
+                pos: "b",
+                lists: [],
+                extensions: {},
+                rooms: {},
+            });
+            slidingSync.modifyRoomSubscriptions(new Set<string>([roomA]));
+            await httpBackend!.flushAllExpected();
+
+            // now the user clicks on a room which uses a custom sub
+            httpBackend!.when("POST", syncUrl).check(function(req) {
+                const body = req.data;
+                logger.log("custom subs", body);
+                expect(body.room_subscriptions).toBeTruthy();
+                expect(body.room_subscriptions[roomB]).toEqual(customSub1);
+                expect(body.unsubscribe_rooms).toEqual([roomA]);
+            }).respond(200, {
+                pos: "b",
+                lists: [],
+                extensions: {},
+                rooms: {},
+            });
+            slidingSync.useCustomSubscription(roomB, customSubName1);
+            slidingSync.modifyRoomSubscriptions(new Set<string>([roomB]));
+            await httpBackend!.flushAllExpected();
+
+            // now the user uses a different sub for the same room: we don't unsub but just resend
+            httpBackend!.when("POST", syncUrl).check(function(req) {
+                const body = req.data;
+                logger.log("custom subs", body);
+                expect(body.room_subscriptions).toBeTruthy();
+                expect(body.room_subscriptions[roomB]).toEqual(customSub2);
+                expect(body.unsubscribe_rooms).toBeFalsy();
+            }).respond(200, {
+                pos: "b",
+                lists: [],
+                extensions: {},
+                rooms: {},
+            });
+            slidingSync.useCustomSubscription(roomB, customSubName2);
+            slidingSync.modifyRoomSubscriptions(new Set<string>([roomB]));
+            await httpBackend!.flushAllExpected();
+
+            slidingSync.stop();
+        });
+
+        it("uses the default subscription for unknown subscription names", async () => {
+            const slidingSync = new SlidingSync(proxyBaseUrl, [], defaultSub, client!, 1);
+            slidingSync.addCustomSubscription(customSubName1, customSub1);
+            slidingSync.useCustomSubscription(roomA, "unknown name");
+            slidingSync.modifyRoomSubscriptions(new Set<string>([roomA]));
+
+            httpBackend!.when("POST", syncUrl).check(function(req) {
+                const body = req.data;
+                logger.log("custom subs", body);
+                expect(body.room_subscriptions).toBeTruthy();
+                expect(body.room_subscriptions[roomA]).toEqual(defaultSub);
+            }).respond(200, {
+                pos: "b",
+                lists: [],
+                extensions: {},
+                rooms: {},
+            });
+            slidingSync.start();
+            await httpBackend!.flushAllExpected();
+            slidingSync.stop();
+        });
+    });
+
     describe("extensions", () => {
         beforeAll(setupClient);
         afterAll(teardownClient);

src/sliding-sync.ts

@@ -353,6 +353,11 @@ export class SlidingSync extends TypedEventEmitter<SlidingSyncEvent, SlidingSync
     private desiredRoomSubscriptions = new Set<string>(); // the *desired* room subscriptions
     private confirmedRoomSubscriptions = new Set<string>();
 
+    // map of custom subscription name to the subscription
+    private customSubscriptions: Map<string, MSC3575RoomSubscription> = new Map();
+    // map of room ID to custom subscription name
+    private roomIdToCustomSubscription: Map<string, string> = new Map();
+
     private pendingReq?: Promise<MSC3575SlidingSyncResponse>;
     private abortController?: AbortController;
 
@@ -375,6 +380,30 @@ export class SlidingSync extends TypedEventEmitter<SlidingSyncEvent, SlidingSync
         this.lists = lists.map((l) => new SlidingList(l));
     }
 
+    /**
+     * Add a custom room subscription, referred to by an arbitrary name. If a subscription with this
+     * name already exists, it is replaced. No requests are sent by calling this method.
+     * @param name The name of the subscription. Only used to reference this subscription in
+     * useCustomSubscription.
+     * @param sub The subscription information.
+     */
+    public addCustomSubscription(name: string, sub: MSC3575RoomSubscription) {
+        this.customSubscriptions.set(name, sub);
+    }
+
+    /**
+     * Use a custom subscription previously added via addCustomSubscription. No requests are sent
+     * by calling this method. Use modifyRoomSubscriptions to resend subscription information.
+     * @param roomId The room to use the subscription in.
+     * @param name The name of the subscription. If this name is unknown, the default subscription
+     * will be used.
+     */
+    public useCustomSubscription(roomId: string, name: string) {
+        this.roomIdToCustomSubscription.set(roomId, name);
+        // unconfirm this subscription so a resend() will send it up afresh.
+        this.confirmedRoomSubscriptions.delete(roomId);
+    }
+
     /**
      * Get the length of the sliding lists.
      * @returns The number of lists in the sync request
@@ -806,7 +835,12 @@ export class SlidingSync extends TypedEventEmitter<SlidingSyncEvent, SlidingSync
                 if (newSubscriptions.size > 0) {
                     reqBody.room_subscriptions = {};
                     for (const roomId of newSubscriptions) {
-                        reqBody.room_subscriptions[roomId] = this.roomSubscriptionInfo;
+                        const customSubName = this.roomIdToCustomSubscription.get(roomId);
+                        let sub = this.roomSubscriptionInfo;
+                        if (customSubName && this.customSubscriptions.has(customSubName)) {
+                            sub = this.customSubscriptions.get(customSubName)!;
+                        }
+                        reqBody.room_subscriptions[roomId] = sub;
                     }
                 }
                 if (this.txnId) {