Server: Performance: Improve performance of updating shared items, generating reports (#13674)

packages/server/src/utils/array.test.ts

@@ -0,0 +1,21 @@
+import { unique } from './array';
+
+describe('array', () => {
+	it('should return unique items in a short array', () => {
+		expect(unique([1, 2, 2, 3, 1])).toEqual([1, 2, 3]);
+	});
+
+	it('should return unique items in a large array', () => {
+		const array = [];
+
+		for (let j = 0; j < 2; j++) {
+			for (let i = 0; i < 1024; i++) {
+				array.push(i);
+			}
+		}
+
+		// Every item should be present twice
+		expect(array).toHaveLength(2048);
+		expect(unique(array)).toHaveLength(1024);
+	});
+});

packages/server/src/utils/array.ts

@@ -1,8 +1,12 @@
 // eslint-disable-next-line @typescript-eslint/no-explicit-any -- Old code before rule was applied
 export function unique(array: any[]): any[] {
-	return array.filter((elem, index, self) => {
-		return index === self.indexOf(elem);
-	});
+	if (array.length < 100) { // O(n^2) branch, but doesn't require creating a Set
+		return array.filter((elem, index, self) => {
+			return index === self.indexOf(elem);
+		});
+	} else { // Faster than O(n^2)
+		return Array.from(new Set(array));
+	}
 }
 
 export const randomElement = <T>(array: T[]): T => {