perf(backend): WebSocket接続が多い場合のパフォーマンスを向上

https: //github.com/MisskeyIO/misskey/pull/176
Co-Authored-By: KOBA789 <kobahide789@gmail.com>

packages/backend/test/unit/misc/loader.ts

@@ -0,0 +1,88 @@
+import { DebounceLoader } from '@/misc/loader.js';
+
+class Mock {
+	loadCountByKey = new Map<number, number>();
+	load = async (key: number): Promise<number> => {
+		const count = this.loadCountByKey.get(key);
+		if (typeof count === 'undefined') {
+			this.loadCountByKey.set(key, 1);
+		} else {
+			this.loadCountByKey.set(key, count + 1);
+		}
+		return key * 2;
+	};
+	reset() {
+		this.loadCountByKey.clear();
+	}
+}
+
+describe(DebounceLoader, () => {
+	describe('single request', () => {
+		it('loads once', async () => {
+			const mock = new Mock();
+			const loader = new DebounceLoader(mock.load);
+			expect(await loader.load(7)).toBe(14);
+			expect(mock.loadCountByKey.size).toBe(1);
+			expect(mock.loadCountByKey.get(7)).toBe(1);
+		});
+	});
+
+	describe('two duplicated requests at same time', () => {
+		it('loads once', async () => {
+			const mock = new Mock();
+			const loader = new DebounceLoader(mock.load);
+			const [v1, v2] = await Promise.all([
+				loader.load(7),
+				loader.load(7),
+			]);
+			expect(v1).toBe(14);
+			expect(v2).toBe(14);
+			expect(mock.loadCountByKey.size).toBe(1);
+			expect(mock.loadCountByKey.get(7)).toBe(1);
+		});
+	});
+
+	describe('two different requests at same time', () => {
+		it('loads twice', async () => {
+			const mock = new Mock();
+			const loader = new DebounceLoader(mock.load);
+			const [v1, v2] = await Promise.all([
+				loader.load(7),
+				loader.load(13),
+			]);
+			expect(v1).toBe(14);
+			expect(v2).toBe(26);
+			expect(mock.loadCountByKey.size).toBe(2);
+			expect(mock.loadCountByKey.get(7)).toBe(1);
+			expect(mock.loadCountByKey.get(13)).toBe(1);
+		});
+	});
+
+	describe('non-continuous same two requests', () => {
+		it('loads twice', async () => {
+			const mock = new Mock();
+			const loader = new DebounceLoader(mock.load);
+			expect(await loader.load(7)).toBe(14);
+			expect(mock.loadCountByKey.size).toBe(1);
+			expect(mock.loadCountByKey.get(7)).toBe(1);
+			mock.reset();
+			expect(await loader.load(7)).toBe(14);
+			expect(mock.loadCountByKey.size).toBe(1);
+			expect(mock.loadCountByKey.get(7)).toBe(1);
+		});
+	});
+
+	describe('non-continuous different two requests', () => {
+		it('loads twice', async () => {
+			const mock = new Mock();
+			const loader = new DebounceLoader(mock.load);
+			expect(await loader.load(7)).toBe(14);
+			expect(mock.loadCountByKey.size).toBe(1);
+			expect(mock.loadCountByKey.get(7)).toBe(1);
+			mock.reset();
+			expect(await loader.load(13)).toBe(26);
+			expect(mock.loadCountByKey.size).toBe(1);
+			expect(mock.loadCountByKey.get(13)).toBe(1);
+		});
+	});
+});