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Don't send prehistorical events to widgets during decryption at startup

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Fixes https://github.com/vector-im/element-web/issues/18060

Tracking a localized read receipt of sorts appears to be the fastest and least complex approach, though not the greatest.
This commit is contained in:
Travis Ralston 2021-08-26 13:28:48 -06:00
parent 470bc0ffe7
commit 20b6219121
1 changed files with 47 additions and 0 deletions
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47
src/stores/widgets/StopGapWidget.ts
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@ -55,6 +55,7 @@ import { MatrixEvent } from "matrix-js-sdk/src/models/event";
import { ELEMENT_CLIENT_ID } from "../../identifiers";
import { getUserLanguage } from "../../languageHandler";
import { WidgetVariableCustomisations } from "../../customisations/WidgetVariables";
import { arrayFastClone } from "../../utils/arrays";
// TODO: Destroy all of this code
@ -146,6 +147,7 @@ export class StopGapWidget extends EventEmitter {
private scalarToken: string;
private roomId?: string;
private kind: WidgetKind;
private readUpToMap: {[roomId: string]: string} = {}; // room ID to event ID
constructor(private appTileProps: IAppTileProps) {
super();
@ -294,6 +296,14 @@ export class StopGapWidget extends EventEmitter {
this.messaging.transport.reply(ev.detail, <IWidgetApiRequestEmptyData>{});
});
// Populate the map of "read up to" events for this widget with the current event in every room.
// This is a bit inefficient, but should be okay. We do this for all rooms in case the widget
// requests timeline capabilities in other rooms down the road. It's just easier to manage here.
for (const room of MatrixClientPeg.get().getRooms()) {
// Timelines are most recent last
this.readUpToMap[room.roomId] = arrayFastClone(room.getLiveTimeline().getEvents()).reverse()[0].getId();
}
// Attach listeners for feeding events - the underlying widget classes handle permissions for us
MatrixClientPeg.get().on('event', this.onEvent);
MatrixClientPeg.get().on('Event.decrypted', this.onEventDecrypted);
@ -421,6 +431,43 @@ export class StopGapWidget extends EventEmitter {
private feedEvent(ev: MatrixEvent) {
if (!this.messaging) return;
// Check to see if this event would be before or after our "read up to" marker. If it's
// before, or we can't decide, then we assume the widget will have already seen the event.
// If the event is after, or we don't have a marker for the room, then we'll send it through.
//
// This approach of "read up to" prevents widgets receiving decryption spam from startup or
// receiving out-of-order events from backfill and such.
const upToEventId = this.readUpToMap[ev.getRoomId()];
if (upToEventId) {
// Small optimization for exact match (prevent search)
if (upToEventId === ev.getId()) {
return;
}
let isBeforeMark = true;
// Timelines are most recent last, so reverse the order and limit ourselves to 100 events
// to avoid overusing the CPU.
const timeline = MatrixClientPeg.get().getRoom(ev.getRoomId()).getLiveTimeline();
const events = arrayFastClone(timeline.getEvents()).reverse().slice(0, 100);
for (const timelineEvent of events) {
if (timelineEvent.getId() === upToEventId) {
break;
} else if (timelineEvent.getId() === ev.getId()) {
isBeforeMark = false;
break;
}
}
if (isBeforeMark) {
// Ignore the event: it is before our interest.
return;
}
}
this.readUpToMap[ev.getRoomId()] = ev.getId();
const raw = ev.getEffectiveEvent();
this.messaging.feedEvent(raw).catch(e => {
console.error("Error sending event to widget: ", e);