extract function to iterate over room response state events

src/matrix/room/ArchivedRoom.js

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import {reduceStateEvents} from "./RoomSummary.js";
+import {iterateResponseStateEvents} from "./common";
 import {BaseRoom} from "./BaseRoom.js";
 import {RoomMember, EVENT_TYPE as MEMBER_EVENT_TYPE} from "./members/RoomMember.js";
 
@@ -173,15 +173,15 @@ export class ArchivedRoom extends BaseRoom {
 }
 
 function findKickDetails(roomResponse, ownUserId) {
-    const kickEvent = reduceStateEvents(roomResponse, (kickEvent, event) => {
+    let kickEvent;
+    iterateResponseStateEvents(roomResponse, event => {
         if (event.type === MEMBER_EVENT_TYPE) {
             // did we get kicked?
             if (event.state_key === ownUserId && event.sender !== event.state_key) {
                 kickEvent = event;
             }
         }
-        return kickEvent;
+    });
-    }, null);
     if (kickEvent) {
         return {
             // this is different from the room membership in the sync section, which can only be leave

src/matrix/room/Room.js

@@ -23,6 +23,7 @@ import {WrappedError} from "../error.js"
 import {Heroes} from "./members/Heroes.js";
 import {AttachmentUpload} from "./AttachmentUpload.js";
 import {DecryptionSource} from "../e2ee/common.js";
+import {iterateResponseStateEvents} from "./common.js";
 import {PowerLevels, EVENT_TYPE as POWERLEVELS_EVENT_TYPE } from "./PowerLevels.js";
 
 const EVENT_ENCRYPTED_TYPE = "m.room.encrypted";
@@ -179,7 +180,7 @@ export class Room extends BaseRoom {
             removedPendingEvents = await this._sendQueue.removeRemoteEchos(roomResponse.timeline.events, txn, log);
         }
         const powerLevelsEvent = this._getPowerLevelsEvent(roomResponse);
-        this._updateRoomStateHandler(roomResponse, txn, log);
+        this._runRoomStateHandlers(roomResponse, txn, log);
         return {
             summaryChanges,
             roomEncryption,
@@ -275,8 +276,13 @@ export class Room extends BaseRoom {
     }
 
     _getPowerLevelsEvent(roomResponse) {
-        const isPowerlevelEvent = event => event.state_key === "" && event.type === POWERLEVELS_EVENT_TYPE;
+        let powerLevelEvent;
-        const powerLevelEvent = roomResponse.timeline?.events.find(isPowerlevelEvent) ?? roomResponse.state?.events.find(isPowerlevelEvent);
+        iterateResponseStateEvents(roomResponse, event => {
+            if(event.state_key === "" && event.type === POWERLEVELS_EVENT_TYPE) {
+                powerLevelEvent = event;
+            }
+
+        });
         return powerLevelEvent;
     }
 
@@ -445,19 +451,11 @@ export class Room extends BaseRoom {
         return this._sendQueue.pendingEvents;
     }
 
-    _updateRoomStateHandler(roomResponse, txn, log) {
+    /** global room state handlers, run during write sync step */
-        const stateEvents = roomResponse.state?.events;
+    _runRoomStateHandlers(roomResponse, txn, log) {
-        if (stateEvents) {
+        iterateResponseStateEvents(roomResponse, event => {
-            for (let i = 0; i < stateEvents.length; i++) {
-                this._roomStateHandler.handleRoomState(this, stateEvents[i], txn, log);
-            }
-        }
-        let timelineEvents = roomResponse.timeline?.events;
-        if (timelineEvents) {
-            for (let i = 0; i < timelineEvents.length; i++) {
-                const event = timelineEvents[i];
-                if (typeof event.state_key === "string") {
             this._roomStateHandler.handleRoomState(this, event, txn, log);
+        });
     }
             }
         }

src/matrix/room/RoomSummary.js

@@ -15,7 +15,7 @@ limitations under the License.
 */
 
 import {MEGOLM_ALGORITHM} from "../e2ee/common.js";
-
+import {iterateResponseStateEvents} from "./common";
 
 function applyTimelineEntries(data, timelineEntries, isInitialSync, canMarkUnread, ownUserId) {
     if (timelineEntries.length) {
@@ -27,25 +27,6 @@ function applyTimelineEntries(data, timelineEntries, isInitialSync, canMarkUnrea
     return data;
 }
 
-export function reduceStateEvents(roomResponse, callback, value) {
-    const stateEvents = roomResponse?.state?.events;
-    // state comes before timeline
-    if (Array.isArray(stateEvents)) {
-        value = stateEvents.reduce(callback, value);
-    }
-    const timelineEvents = roomResponse?.timeline?.events;
-    // and after that state events in the timeline
-    if (Array.isArray(timelineEvents)) {
-        value = timelineEvents.reduce((data, event) => {
-            if (typeof event.state_key === "string") {
-                value = callback(value, event);
-            }
-            return value;
-        }, value);
-    }
-    return value;
-}
-
 function applySyncResponse(data, roomResponse, membership, ownUserId) {
     if (roomResponse.summary) {
         data = updateSummary(data, roomResponse.summary);
@@ -60,7 +41,9 @@ function applySyncResponse(data, roomResponse, membership, ownUserId) {
     // process state events in state and in timeline.
     // non-state events are handled by applyTimelineEntries
     // so decryption is handled properly
-    data = reduceStateEvents(roomResponse, (data, event) => processStateEvent(data, event, ownUserId), data);
+    iterateResponseStateEvents(roomResponse, event => {
+        data = processStateEvent(data, event, ownUserId);
+    });
     const unreadNotifications = roomResponse.unread_notifications;
     if (unreadNotifications) {
         data = processNotificationCounts(data, unreadNotifications);

src/matrix/room/common.ts

@@ -15,7 +15,7 @@ limitations under the License.
 */
 
 import type {Room} from "./Room";
-import type {StateEvent} from "../storage/types";
+import type {StateEvent, TimelineEvent} from "../storage/types";
 import type {Transaction} from "../storage/idb/Transaction";
 import type {ILogItem} from "../../logging/types";
 import type {MemberChange} from "./members/RoomMember";
@@ -50,4 +50,71 @@ export enum RoomType {
 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>
+    },
+    timeline?: {
+        events?: Array<StateEvent>
+    }
+}
+
+/** iterates over any state events in a sync room response, in the order that they should be applied (from older to younger events) */
+export function iterateResponseStateEvents(roomResponse: RoomResponse, callback: (StateEvent) => void) {
+    // first iterate over state events, they precede the timeline
+    const stateEvents = roomResponse.state?.events;
+    if (stateEvents) {
+        for (let i = 0; i < stateEvents.length; i++) {
+            callback(stateEvents[i]);
+        }
+    }
+    // now see if there are any state events within the timeline
+    let timelineEvents = roomResponse.timeline?.events;
+    if (timelineEvents) {
+        for (let i = 0; i < timelineEvents.length; i++) {
+            const event = timelineEvents[i];
+            if (typeof event.state_key === "string") {
+                callback(event);
+            }
+        }
+    }
+}
+
+export function tests() {
+    return {
+        "test iterateResponseStateEvents with both state and timeline sections": assert => {
+            const roomResponse = {
+                state: {
+                    events: [
+                        {type: "m.room.member", state_key: "1"},
+                        {type: "m.room.member", state_key: "2", content: {a: 1}},
+                    ]
+                },
+                timeline: {
+                    events: [
+                        {type: "m.room.message"},
+                        {type: "m.room.member", state_key: "3"},
+                        {type: "m.room.message"},
+                        {type: "m.room.member", state_key: "2", content: {a: 2}},
+                    ]
+                }
+            } as unknown as RoomResponse;
+            const expectedStateKeys = ["1", "2", "3", "2"];
+            const expectedAForMember2 = [1, 2];
+            iterateResponseStateEvents(roomResponse, event => {
+                assert.strictEqual(event.type, "m.room.member");
+                assert.strictEqual(expectedStateKeys.shift(), event.state_key);
+                if (event.state_key === "2") {
+                    assert.strictEqual(expectedAForMember2.shift(), event.content.a);
+                }
+            });
+            assert.strictEqual(expectedStateKeys.length, 0);
+            assert.strictEqual(expectedAForMember2.length, 0);
+        },
+        "test iterateResponseStateEvents with empty response": assert => {
+            iterateResponseStateEvents({}, () => {
+                assert.fail("no events expected");
+            });
+        }
+    }
 }