Avoid looking up settings during timeline rendering (#8313)

* Avoid showHiddenEventsInTimeline lookups

* Avoid MSC3531 feature lookups

* Test that showHiddenEventsInTimeline doesn't get looked up while
rendering

* Fix code review nits

Co-authored-by: Travis Ralston <travisr@matrix.org>

src/utils/EventRenderingUtils.ts

@@ -25,7 +25,7 @@ import { haveRendererForEvent, JitsiEventFactory, JSONEventFactory, pickFactory
 import { MatrixClientPeg } from "../MatrixClientPeg";
 import { getMessageModerationState, MessageModerationState } from "./EventUtils";
 
-export function getEventDisplayInfo(mxEvent: MatrixEvent, hideEvent?: boolean): {
+export function getEventDisplayInfo(mxEvent: MatrixEvent, showHiddenEvents: boolean, hideEvent?: boolean): {
     isInfoMessage: boolean;
     hasRenderer: boolean;
     isBubbleMessage: boolean;
@@ -52,7 +52,7 @@ export function getEventDisplayInfo(mxEvent: MatrixEvent, hideEvent?: boolean):
     }
 
     // TODO: Thread a MatrixClient through to here
-    let factory = pickFactory(mxEvent, MatrixClientPeg.get());
+    let factory = pickFactory(mxEvent, MatrixClientPeg.get(), showHiddenEvents);
 
     // Info messages are basically information about commands processed on a room
     let isBubbleMessage = (
@@ -92,11 +92,11 @@ export function getEventDisplayInfo(mxEvent: MatrixEvent, hideEvent?: boolean):
     // source tile when there's no regular tile for an event and also for
     // replace relations (which otherwise would display as a confusing
     // duplicate of the thing they are replacing).
-    if (hideEvent || !haveRendererForEvent(mxEvent)) {
+    if (hideEvent || !haveRendererForEvent(mxEvent, showHiddenEvents)) {
         // forcefully ask for a factory for a hidden event (hidden event
         // setting is checked internally)
         // TODO: Thread a MatrixClient through to here
-        factory = pickFactory(mxEvent, MatrixClientPeg.get(), true);
+        factory = pickFactory(mxEvent, MatrixClientPeg.get(), showHiddenEvents, true);
         if (factory === JSONEventFactory) {
             isBubbleMessage = false;
             // Reuse info message avatar and sender profile styling

src/utils/EventUtils.ts

@@ -151,6 +151,16 @@ export enum MessageModerationState {
     SEE_THROUGH_FOR_CURRENT_USER = "SEE_THROUGH_FOR_CURRENT_USER",
 }
 
+// This is lazily initialized and cached since getMessageModerationState needs it,
+// and is called on timeline rendering hot-paths
+let msc3531Enabled: boolean | null = null;
+const getMsc3531Enabled = (): boolean => {
+    if (msc3531Enabled === null) {
+        msc3531Enabled = SettingsStore.getValue("feature_msc3531_hide_messages_pending_moderation");
+    }
+    return msc3531Enabled;
+};
+
 /**
  * Determine whether a message should be displayed as hidden pending moderation.
  *
@@ -160,7 +170,7 @@ export enum MessageModerationState {
 export function getMessageModerationState(mxEvent: MatrixEvent, client?: MatrixClient): MessageModerationState {
     client = client ?? MatrixClientPeg.get(); // because param defaults don't do the correct thing
 
-    if (!SettingsStore.getValue("feature_msc3531_hide_messages_pending_moderation")) {
+    if (!getMsc3531Enabled()) {
         return MessageModerationState.VISIBLE_FOR_ALL;
     }
     const visibility = mxEvent.messageVisibility();

src/utils/exportUtils/HtmlExport.tsx

@@ -407,7 +407,7 @@ export default class HTMLExporter extends Exporter {
                 total: events.length,
             }), false, true);
             if (this.cancelled) return this.cleanUp();
-            if (!haveRendererForEvent(event)) continue;
+            if (!haveRendererForEvent(event, false)) continue;
 
             content += this.needsDateSeparator(event, prevEvent) ? this.getDateSeparator(event) : "";
             const shouldBeJoined = !this.needsDateSeparator(event, prevEvent) &&

src/utils/exportUtils/JSONExport.ts

@@ -85,7 +85,7 @@ export default class JSONExporter extends Exporter {
                 total: events.length,
             }), false, true);
             if (this.cancelled) return this.cleanUp();
-            if (!haveRendererForEvent(event)) continue;
+            if (!haveRendererForEvent(event, false)) continue;
             this.messages.push(await this.getJSONString(event));
         }
         return this.createJSONString();

src/utils/exportUtils/PlainTextExport.ts

@@ -112,7 +112,7 @@ export default class PlainTextExporter extends Exporter {
                 total: events.length,
             }), false, true);
             if (this.cancelled) return this.cleanUp();
-            if (!haveRendererForEvent(event)) continue;
+            if (!haveRendererForEvent(event, false)) continue;
             const textForEvent = await this.plainTextForEvent(event);
             content += textForEvent && `${new Date(event.getTs()).toLocaleString()} - ${textForEvent}\n`;
         }