add support for observing room state for single room + initial state

src/lib.ts

@@ -22,7 +22,7 @@ export {Platform} from "./platform/web/Platform.js";
 export {Client, LoadStatus} from "./matrix/Client.js";
 export {RoomStatus} from "./matrix/room/common";
 // export everything needed to observe state events on all rooms using session.observeRoomState
-export type {RoomStateHandler} from "./matrix/room/common";
+export type {RoomStateHandler} from "./matrix/room/state/types";
 export type {MemberChange} from "./matrix/room/members/RoomMember";
 export type {Transaction} from "./matrix/storage/idb/Transaction";
 export type {Room} from "./matrix/room/Room";

src/matrix/Session.js

@@ -48,7 +48,7 @@ import {SecretStorage} from "./ssss/SecretStorage";
 import {ObservableValue} from "../observable/value/ObservableValue";
 import {RetainedObservableValue} from "../observable/value/RetainedObservableValue";
 import {CallHandler} from "./calls/CallHandler";
-import {RoomStateHandlerSet} from "./RoomStateHandlerSet";
+import {RoomStateHandlerSet} from "./room/state/RoomStateHandlerSet";
 
 const PICKLE_KEY = "DEFAULT_KEY";
 const PUSHER_KEY = "pusher";

src/matrix/calls/CallHandler.ts

@@ -35,7 +35,7 @@ import type {Options as GroupCallOptions} from "./group/GroupCall";
 import type {Transaction} from "../storage/idb/Transaction";
 import type {CallEntry} from "../storage/idb/stores/CallStore";
 import type {Clock} from "../../platform/web/dom/Clock";
-import type {RoomStateHandler} from "../room/common";
+import type {RoomStateHandler} from "../room/state/types";
 
 export type Options = Omit<GroupCallOptions, "emitUpdate" | "createTimeout"> & {
     clock: Clock

src/matrix/room/BaseRoom.js

@@ -31,6 +31,8 @@ import {ensureLogItem} from "../../logging/utils";
 import {PowerLevels} from "./PowerLevels.js";
 import {RetainedObservableValue} from "../../observable/value/RetainedObservableValue";
 import {TimelineReader} from "./timeline/persistence/TimelineReader";
+import {ObservedStateTypeMap} from "./state/ObservedStateTypeMap";
+import {ObservedStateKeyValue} from "./state/ObservedStateKeyValue";
 
 const EVENT_ENCRYPTED_TYPE = "m.room.encrypted";
 
@@ -53,11 +55,35 @@ export class BaseRoom extends EventEmitter {
         this._getSyncToken = getSyncToken;
         this._platform = platform;
         this._observedEvents = null;
+        this._roomStateObservers = new Set();
         this._powerLevels = null;
         this._powerLevelLoading = null;
         this._observedMembers = null;
     }
 
+    async observeStateType(type, txn = undefined) {
+        const map = new ObservedStateTypeMap(type);
+        await this._addStateObserver(map, txn);
+        return map;
+    }
+
+    async observeStateTypeAndKey(type, stateKey, txn = undefined) {
+        const value = new ObservedStateKeyValue(type, stateKey);
+        await this._addStateObserver(value, txn);
+        return value;
+    }
+
+    async _addStateObserver(stateObserver, txn) {
+        if (!txn) {
+            txn = await this._storage.readTxn([this._storage.storeNames.roomState]);
+        }
+        await stateObserver.load(this.id, txn);
+        this._roomStateObservers.add(stateObserver);
+        stateObserver.setRemoveCallback(() => {
+            this._roomStateObservers.delete(stateObserver);
+        });
+    }
+
     async _eventIdsToEntries(eventIds, txn) {
         const retryEntries = [];
         await Promise.all(eventIds.map(async eventId => {

src/matrix/room/Room.js

@@ -182,6 +182,7 @@ export class Room extends BaseRoom {
         const powerLevelsEvent = this._getPowerLevelsEvent(roomResponse);
         this._runRoomStateHandlers(roomResponse, txn, log);
         return {
+            roomResponse,
             summaryChanges,
             roomEncryption,
             newEntries,
@@ -204,7 +205,7 @@ export class Room extends BaseRoom {
         const {
             summaryChanges, newEntries, updatedEntries, newLiveKey,
             removedPendingEvents, memberChanges, powerLevelsEvent,
-            heroChanges, roomEncryption
+            heroChanges, roomEncryption, roomResponse
         } = changes;
         log.set("id", this.id);
         this._syncWriter.afterSync(newLiveKey);
@@ -264,6 +265,7 @@ export class Room extends BaseRoom {
         if (removedPendingEvents) {
             this._sendQueue.emitRemovals(removedPendingEvents);
         }
+        this._emitSyncRoomState(roomResponse);
     }
 
     _updateObservedMembers(memberChanges) {
@@ -457,8 +459,14 @@ export class Room extends BaseRoom {
             this._roomStateHandler.handleRoomState(this, event, txn, log);
         });
     }
+
+    /** local room state observers, run during after sync step */
+    _emitSyncRoomState(roomResponse) {
+        iterateResponseStateEvents(roomResponse, event => {
+            for (const handler of this._roomStateObservers) {
+                handler.handleStateEvent(event);
             }
-        }
+        });
     }
 
     /** @package */

src/matrix/room/common.ts

@@ -47,9 +47,6 @@ export enum RoomType {
     Public
 }
 
-export interface RoomStateHandler {
-    handleRoomState(room: Room, stateEvent: StateEvent, txn: Transaction, log: ILogItem);
-    updateRoomMembers(room: Room, memberChanges: Map<string, MemberChange>);
 type RoomResponse = {
     state?: {
         events?: Array<StateEvent>

src/matrix/room/state/ObservedStateKeyValue.ts

@@ -0,0 +1,55 @@
+/*
+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.
+*/
+
+import type {StateObserver} from "./types";
+import type {StateEvent} from "../../storage/types";
+import type {Transaction} from "../../storage/idb/Transaction";
+import {BaseObservableValue} from "../../../observable/value/BaseObservableValue";
+
+/**
+ * Observable value for a state event with a given type and state key.
+ * Unsubscribes when last subscription is removed */
+export class ObservedStateKeyValue extends BaseObservableValue<StateEvent | undefined> implements StateObserver {
+    private event?: StateEvent;
+    private removeCallback?: () => void;
+
+    constructor(private readonly type: string, private readonly stateKey: string) {
+        super();
+    }
+    /** @internal */
+    async load(roomId: string, txn: Transaction): Promise<void> {
+        this.event = (await txn.roomState.get(roomId, this.type, this.stateKey))?.event;
+    }
+    /** @internal */
+    handleStateEvent(event: StateEvent) {
+        if (event.type === this.type && event.state_key === this.stateKey) {
+            this.event = event;
+            this.emit(this.get());
+        }
+    }
+
+    get(): StateEvent | undefined {
+        return this.event;
+    }
+
+    setRemoveCallback(callback: () => void) {
+        this.removeCallback = callback;
+    }
+
+    onUnsubscribeLast() {
+        this.removeCallback?.();
+    }
+}

src/matrix/room/state/ObservedStateTypeMap.ts

@@ -0,0 +1,53 @@
+/*
+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.
+*/
+
+import type {StateObserver} from "./types";
+import type {StateEvent} from "../../storage/types";
+import type {Transaction} from "../../storage/idb/Transaction";
+import {ObservableMap} from "../../../observable/map/ObservableMap";
+
+/**
+ * Observable map for a given type with state keys as map keys.
+ * Unsubscribes when last subscription is removed */
+export class ObservedStateTypeMap extends ObservableMap<string, StateEvent> implements StateObserver {
+    private removeCallback?: () => void;
+    
+    constructor(private readonly type: string) {
+        super();
+    }
+    /** @internal */
+    async load(roomId: string, txn: Transaction): Promise<void> {
+        const events = await txn.roomState.getAllForType(roomId, this.type);
+        for (let i = 0; i < events.length; ++i) {
+            const {event} = events[i];
+            this.add(event.state_key, event);
+        }
+    }
+    /** @internal */
+    handleStateEvent(event: StateEvent) {
+        if (event.type === this.type) {
+            this.set(event.state_key, event);
+        }
+    }
+
+    setRemoveCallback(callback: () => void) {
+        this.removeCallback = callback;
+    }
+
+    onUnsubscribeLast() {
+        this.removeCallback?.();
+    }
+}

src/matrix/room/state/RoomStateHandlerSet.ts

@@ -14,13 +14,13 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import type {ILogItem} from "../logging/types";
+import type {ILogItem} from "../../../logging/types";
-import type {StateEvent} from "./storage/types";
+import type {StateEvent} from "../../storage/types";
-import type {Transaction} from "./storage/idb/Transaction";
+import type {Transaction} from "../../storage/idb/Transaction";
-import type {Room} from "./room/Room";
+import type {Room} from "../Room";
-import type {MemberChange} from "./room/members/RoomMember";
+import type {MemberChange} from "../members/RoomMember";
-import type {RoomStateHandler} from "./room/common";
+import type {RoomStateHandler} from "./types";
-import {BaseObservable} from "../observable/BaseObservable";
+import {BaseObservable} from "../../../observable/BaseObservable";
 
 /** keeps track of all handlers registered with Session.observeRoomState */
 export class RoomStateHandlerSet extends BaseObservable<RoomStateHandler> implements RoomStateHandler {

src/matrix/room/state/types.ts

@@ -0,0 +1,38 @@
+/*
+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.
+*/
+
+import type {Room} from "../Room";
+import type {StateEvent} from "../../storage/types";
+import type {Transaction} from "../../storage/idb/Transaction";
+import type {ILogItem} from "../../../logging/types";
+import type {MemberChange} from "../members/RoomMember";
+
+/** used for Session.observeRoomState, which observes in all room, but without loading from storage
+ * It receives the sync write transaction, so other stores can be updated as part of the same transaction. */
+export interface RoomStateHandler {
+    handleRoomState(room: Room, stateEvent: StateEvent, syncWriteTxn: Transaction, log: ILogItem);
+    updateRoomMembers(room: Room, memberChanges: Map<string, MemberChange>);
+}
+
+/**
+ * used for Room.observeStateType and Room.observeStateTypeAndKey
+ * @internal
+ * */
+export interface StateObserver {
+    handleStateEvent(event: StateEvent);
+    load(roomId: string, txn: Transaction): Promise<void>;
+    setRemoveCallback(callback: () => void);
+}