From 2859cbab913dc836f4beb55cf967d1feeb87e6c3 Mon Sep 17 00:00:00 2001
From: syuilo <Syuilotan@yahoo.co.jp>
Date: Sun, 8 Oct 2023 08:10:28 +0900
Subject: perf(backend): WebSocket接続が多い場合のパフォーマンスを向上
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https: //github.com/MisskeyIO/misskey/pull/176
Co-Authored-By: KOBA789 <kobahide789@gmail.com>
---
 .../backend/src/core/entities/NoteEntityService.ts | 12 ++++-
 packages/backend/src/misc/loader.ts                | 52 ++++++++++++++++++++++
 2 files changed, 63 insertions(+), 1 deletion(-)
 create mode 100644 packages/backend/src/misc/loader.ts

(limited to 'packages/backend/src')

diff --git a/packages/backend/src/core/entities/NoteEntityService.ts b/packages/backend/src/core/entities/NoteEntityService.ts
index e45a7992bb..abe4aafd6e 100644
--- a/packages/backend/src/core/entities/NoteEntityService.ts
+++ b/packages/backend/src/core/entities/NoteEntityService.ts
@@ -17,6 +17,7 @@ import type { MiNoteReaction } from '@/models/NoteReaction.js';
 import type { UsersRepository, NotesRepository, FollowingsRepository, PollsRepository, PollVotesRepository, NoteReactionsRepository, ChannelsRepository } from '@/models/_.js';
 import { bindThis } from '@/decorators.js';
 import { isNotNull } from '@/misc/is-not-null.js';
+import { DebounceLoader } from '@/misc/loader.js';
 import type { OnModuleInit } from '@nestjs/common';
 import type { CustomEmojiService } from '../CustomEmojiService.js';
 import type { ReactionService } from '../ReactionService.js';
@@ -29,6 +30,7 @@ export class NoteEntityService implements OnModuleInit {
 	private driveFileEntityService: DriveFileEntityService;
 	private customEmojiService: CustomEmojiService;
 	private reactionService: ReactionService;
+	private noteLoader = new DebounceLoader(this.findNoteOrFail);
 
 	constructor(
 		private moduleRef: ModuleRef,
@@ -285,7 +287,7 @@ export class NoteEntityService implements OnModuleInit {
 		}, options);
 
 		const meId = me ? me.id : null;
-		const note = typeof src === 'object' ? src : await this.notesRepository.findOneOrFail({ where: { id: src }, relations: ['user'] });
+		const note = typeof src === 'object' ? src : await this.noteLoader.load(src);
 		const host = note.userHost;
 
 		let text = note.text;
@@ -450,4 +452,12 @@ export class NoteEntityService implements OnModuleInit {
 		}
 		return emojis.filter(x => x.name != null && x.host != null) as { name: string; host: string; }[];
 	}
+
+	@bindThis
+	private findNoteOrFail(id: string): Promise<MiNote> {
+		return this.notesRepository.findOneOrFail({
+			where: { id },
+			relations: ['user'],
+		});
+	}
 }
diff --git a/packages/backend/src/misc/loader.ts b/packages/backend/src/misc/loader.ts
new file mode 100644
index 0000000000..25f7b54d31
--- /dev/null
+++ b/packages/backend/src/misc/loader.ts
@@ -0,0 +1,52 @@
+export type FetchFunction<K, V> = (key: K) => Promise<V>;
+
+type ResolveReject<V> = Parameters<ConstructorParameters<typeof Promise<V>>[0]>;
+
+type ResolverPair<V> = {
+	resolve: ResolveReject<V>[0];
+	reject: ResolveReject<V>[1];
+};
+
+export class DebounceLoader<K, V> {
+	private resolverMap = new Map<K, ResolverPair<V>>();
+	private promiseMap = new Map<K, Promise<V>>();
+	private resolvedPromise = Promise.resolve();
+	constructor(private loadFn: FetchFunction<K, V>) {}
+
+	public load(key: K): Promise<V> {
+		const promise = this.promiseMap.get(key);
+		if (typeof promise !== 'undefined') {
+			return promise;
+		}
+
+		const isFirst = this.promiseMap.size === 0;
+		const newPromise = new Promise<V>((resolve, reject) => {
+			this.resolverMap.set(key, { resolve, reject });
+		});
+		this.promiseMap.set(key, newPromise);
+
+		if (isFirst) {
+			this.enqueueDebouncedLoadJob();
+		}
+
+		return newPromise;
+	}
+
+	private runDebouncedLoad(): void {
+		const resolvers = [...this.resolverMap];
+		this.resolverMap.clear();
+		this.promiseMap.clear();
+
+		for (const [key, { resolve, reject }] of resolvers) {
+			this.loadFn(key).then(resolve, reject);
+		}
+	}
+
+	private enqueueDebouncedLoadJob(): void {
+		this.resolvedPromise.then(() => {
+			process.nextTick(() => {
+				this.runDebouncedLoad();
+			});
+		});
+	}
+}
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