fix(Postgres Node): Re-use connection pool across executions (#12346)

Co-authored-by: कारतोफ्फेलस्क्रिप्ट™ <aditya@netroy.in>

packages/nodes-base/utils/__tests__/connection-pool-manager.test.ts

@@ -0,0 +1,179 @@
+import { ConnectionPoolManager } from '@utils/connection-pool-manager';
+
+const ttl = 5 * 60 * 1000;
+const cleanUpInterval = 60 * 1000;
+
+let cpm: ConnectionPoolManager;
+
+beforeAll(() => {
+	jest.useFakeTimers();
+	cpm = ConnectionPoolManager.getInstance();
+});
+
+beforeEach(async () => {
+	await cpm.purgeConnections();
+});
+
+afterAll(() => {
+	cpm.onShutdown();
+});
+
+test('getInstance returns a singleton', () => {
+	const instance1 = ConnectionPoolManager.getInstance();
+	const instance2 = ConnectionPoolManager.getInstance();
+
+	expect(instance1).toBe(instance2);
+});
+
+describe('getConnection', () => {
+	test('calls fallBackHandler only once and returns the first value', async () => {
+		// ARRANGE
+		const connectionType = {};
+		const fallBackHandler = jest.fn().mockResolvedValue(connectionType);
+		const cleanUpHandler = jest.fn();
+		const options = {
+			credentials: {},
+			nodeType: 'example',
+			nodeVersion: '1',
+			fallBackHandler,
+			cleanUpHandler,
+		};
+
+		// ACT 1
+		const connection = await cpm.getConnection<string>(options);
+
+		// ASSERT 1
+		expect(fallBackHandler).toHaveBeenCalledTimes(1);
+		expect(connection).toBe(connectionType);
+
+		// ACT 2
+		const connection2 = await cpm.getConnection<string>(options);
+		// ASSERT 2
+		expect(fallBackHandler).toHaveBeenCalledTimes(1);
+		expect(connection2).toBe(connectionType);
+	});
+
+	test('creates different pools for different node versions', async () => {
+		// ARRANGE
+		const connectionType1 = {};
+		const fallBackHandler1 = jest.fn().mockResolvedValue(connectionType1);
+		const cleanUpHandler1 = jest.fn();
+
+		const connectionType2 = {};
+		const fallBackHandler2 = jest.fn().mockResolvedValue(connectionType2);
+		const cleanUpHandler2 = jest.fn();
+
+		// ACT 1
+		const connection1 = await cpm.getConnection<string>({
+			credentials: {},
+			nodeType: 'example',
+			nodeVersion: '1',
+			fallBackHandler: fallBackHandler1,
+			cleanUpHandler: cleanUpHandler1,
+		});
+		const connection2 = await cpm.getConnection<string>({
+			credentials: {},
+			nodeType: 'example',
+			nodeVersion: '2',
+			fallBackHandler: fallBackHandler2,
+			cleanUpHandler: cleanUpHandler2,
+		});
+
+		// ASSERT
+		expect(fallBackHandler1).toHaveBeenCalledTimes(1);
+		expect(connection1).toBe(connectionType1);
+
+		expect(fallBackHandler2).toHaveBeenCalledTimes(1);
+		expect(connection2).toBe(connectionType2);
+
+		expect(connection1).not.toBe(connection2);
+	});
+
+	test('calls cleanUpHandler after TTL expires', async () => {
+		// ARRANGE
+		const connectionType = {};
+		const fallBackHandler = jest.fn().mockResolvedValue(connectionType);
+		const cleanUpHandler = jest.fn();
+		await cpm.getConnection<string>({
+			credentials: {},
+			nodeType: 'example',
+			nodeVersion: '1',
+			fallBackHandler,
+			cleanUpHandler,
+		});
+
+		// ACT
+		jest.advanceTimersByTime(ttl + cleanUpInterval * 2);
+
+		// ASSERT
+		expect(cleanUpHandler).toHaveBeenCalledTimes(1);
+	});
+});
+
+describe('onShutdown', () => {
+	test('calls all clean up handlers', async () => {
+		// ARRANGE
+		const connectionType1 = {};
+		const fallBackHandler1 = jest.fn().mockResolvedValue(connectionType1);
+		const cleanUpHandler1 = jest.fn();
+		await cpm.getConnection<string>({
+			credentials: {},
+			nodeType: 'example',
+			nodeVersion: '1',
+			fallBackHandler: fallBackHandler1,
+			cleanUpHandler: cleanUpHandler1,
+		});
+
+		const connectionType2 = {};
+		const fallBackHandler2 = jest.fn().mockResolvedValue(connectionType2);
+		const cleanUpHandler2 = jest.fn();
+		await cpm.getConnection<string>({
+			credentials: {},
+			nodeType: 'example',
+			nodeVersion: '2',
+			fallBackHandler: fallBackHandler2,
+			cleanUpHandler: cleanUpHandler2,
+		});
+
+		// ACT 1
+		cpm.onShutdown();
+
+		// ASSERT
+		expect(cleanUpHandler1).toHaveBeenCalledTimes(1);
+		expect(cleanUpHandler2).toHaveBeenCalledTimes(1);
+	});
+
+	test('calls all clean up handlers when `exit` is emitted on process', async () => {
+		// ARRANGE
+		const connectionType1 = {};
+		const fallBackHandler1 = jest.fn().mockResolvedValue(connectionType1);
+		const cleanUpHandler1 = jest.fn();
+		await cpm.getConnection<string>({
+			credentials: {},
+			nodeType: 'example',
+			nodeVersion: '1',
+			fallBackHandler: fallBackHandler1,
+			cleanUpHandler: cleanUpHandler1,
+		});
+
+		const connectionType2 = {};
+		const fallBackHandler2 = jest.fn().mockResolvedValue(connectionType2);
+		const cleanUpHandler2 = jest.fn();
+		await cpm.getConnection<string>({
+			credentials: {},
+			nodeType: 'example',
+			nodeVersion: '2',
+			fallBackHandler: fallBackHandler2,
+			cleanUpHandler: cleanUpHandler2,
+		});
+
+		// ACT 1
+		// @ts-expect-error we're not supposed to emit `exit` so it's missing from
+		// the type definition
+		process.emit('exit');
+
+		// ASSERT
+		expect(cleanUpHandler1).toHaveBeenCalledTimes(1);
+		expect(cleanUpHandler2).toHaveBeenCalledTimes(1);
+	});
+});