fix(core): improve performance (#6345)

packages/common/infra/src/livedata/livedata.ts

@@ -5,20 +5,22 @@ import type {
   OperatorFunction,
   Subscription,
   TeardownLogic,
+  ThrottleConfig,
 } from 'rxjs';
 import {
   BehaviorSubject,
   combineLatest,
   distinctUntilChanged,
   EMPTY,
-  filter,
   map,
+  mergeMap,
   Observable,
   of,
   scan,
   skip,
   Subject,
   switchMap,
+  throttleTime,
 } from 'rxjs';
 
 const logger = new DebugLogger('livedata');
@@ -97,11 +99,10 @@ export class LiveData<T = unknown>
         ? upstream$
         : stream$ =>
             stream$.pipe(
-              filter(
-                (op): op is Exclude<LiveDataOperation, 'set'> => op !== 'set'
-              ),
-              switchMap(v => {
-                if (v === 'get') {
+              mergeMap(v => {
+                if (v === 'set') {
+                  return EMPTY;
+                } else if (v === 'get') {
                   return of('watch' as const, 'unwatch' as const);
                 } else {
                   return of(v);
@@ -333,6 +334,23 @@ export class LiveData<T = unknown>
     return sub$;
   }
 
+  distinctUntilChanged(comparator?: (previous: T, current: T) => boolean) {
+    return LiveData.from(
+      this.pipe(distinctUntilChanged(comparator)),
+      null as any
+    );
+  }
+
+  throttleTime(
+    duration: number,
+    { trailing = true, leading = true }: ThrottleConfig = {}
+  ) {
+    return LiveData.from(
+      this.pipe(throttleTime(duration, undefined, { trailing, leading })),
+      null as any
+    );
+  }
+
   // eslint-disable-next-line rxjs/finnish
   asObservable(): Observable<T> {
     return new Observable<T>(subscriber => {

packages/common/infra/src/page/record.ts

@@ -8,6 +8,7 @@ import type { Workspace, WorkspaceLocalState } from '../workspace';
 export type PageMode = 'edgeless' | 'page';
 
 export class PageRecord {
+  meta: Partial<DocMeta> | null = null;
   constructor(
     public readonly id: string,
     private readonly workspace: Workspace,
@@ -15,15 +16,14 @@ export class PageRecord {
   ) {}
 
   meta$ = LiveData.from<Partial<DocMeta>>(
-    new Observable<DocMeta>(subscriber => {
+    new Observable<Partial<DocMeta>>(subscriber => {
       const emit = () => {
-        const meta = this.workspace.docCollection.meta.docMetas.find(
-          page => page.id === this.id
-        );
-        if (meta === undefined) {
-          return;
+        if (this.meta === null) {
+          // getDocMeta is heavy, so we cache the doc meta reference
+          this.meta =
+            this.workspace.docCollection.meta.getDocMeta(this.id) || null;
         }
-        subscriber.next(meta);
+        subscriber.next({ ...this.meta });
       };
 
       emit();