chore(auth): debounce refreshAuthTokens

packages/aws-amplify/package.json

@@ -396,19 +396,19 @@
 			"name": "[Auth] fetchMFAPreference (Cognito)",
 			"path": "./dist/esm/auth/index.mjs",
 			"import": "{ fetchMFAPreference }",
-			"limit": "8.30 kB"
+			"limit": "8.35 kB"
 		},
 		{
 			"name": "[Auth] verifyTOTPSetup (Cognito)",
 			"path": "./dist/esm/auth/index.mjs",
 			"import": "{ verifyTOTPSetup }",
-			"limit": "9.13 kB"
+			"limit": "9.16 kB"
 		},
 		{
 			"name": "[Auth] updatePassword (Cognito)",
 			"path": "./dist/esm/auth/index.mjs",
 			"import": "{ updatePassword }",
-			"limit": "9.14 kB"
+			"limit": "9.17 kB"
 		},
 		{
 			"name": "[Auth] setUpTOTP (Cognito)",
@@ -420,7 +420,7 @@
 			"name": "[Auth] updateUserAttributes (Cognito)",
 			"path": "./dist/esm/auth/index.mjs",
 			"import": "{ updateUserAttributes }",
-			"limit": "8.41 kB"
+			"limit": "8.45 kB"
 		},
 		{
 			"name": "[Auth] getCurrentUser (Cognito)",
@@ -432,7 +432,7 @@
 			"name": "[Auth] confirmUserAttribute (Cognito)",
 			"path": "./dist/esm/auth/index.mjs",
 			"import": "{ confirmUserAttribute }",
-			"limit": "9.15 kB"
+			"limit": "9.17 kB"
 		},
 		{
 			"name": "[Auth] signInWithRedirect (Cognito)",

packages/core/__tests__/utils/debounceCallback.test.ts

@@ -0,0 +1,46 @@
+import { debounceCallback } from '../../src/utils/debounceCallback';
+
+describe('test debounce callback', () => {
+	const numberOfConcurrentCalls = 10;
+	const mockServiceCallback = jest.fn();
+
+	afterEach(() => {
+		mockServiceCallback.mockClear();
+	});
+
+	it('should allow to invoke the callback when there is no concurrent calls', async () => {
+		const debouncedCallback = debounceCallback(mockServiceCallback);
+
+		debouncedCallback();
+		expect(mockServiceCallback).toHaveBeenCalledTimes(1);
+	});
+
+	it('should invoke the callback one time during concurrent sync calls', () => {
+		const debouncedCallback = debounceCallback(mockServiceCallback);
+		for (let i = 0; i < numberOfConcurrentCalls; i++) {
+			debouncedCallback();
+		}
+		expect(mockServiceCallback).toHaveBeenCalledTimes(1);
+	});
+
+	it('should allow to invoke the callback again after the promise has being resolved', async () => {
+		const debouncedCallback = debounceCallback(mockServiceCallback);
+		for (let i = 0; i < numberOfConcurrentCalls; i++) {
+			debouncedCallback();
+		}
+
+		await debouncedCallback();
+
+		debouncedCallback();
+		expect(mockServiceCallback).toHaveBeenCalledTimes(2);
+	});
+
+	it('should return a value once the callback is resolved', async () => {
+		const mockReturnValue = { id: 1 };
+		mockServiceCallback.mockImplementation(() => mockReturnValue);
+		const debouncedCallback = debounceCallback(mockServiceCallback);
+		const result = await debouncedCallback();
+		expect(result).toEqual(mockReturnValue);
+		expect(mockServiceCallback).toHaveBeenCalledTimes(1);
+	});
+});

packages/core/src/singleton/apis/fetchAuthSession.ts

@@ -3,10 +3,11 @@
 
 import { fetchAuthSession as fetchAuthSessionInternal } from './internal/fetchAuthSession';
 import { Amplify } from '../Amplify';
-import { AuthSession, FetchAuthSessionOptions } from '../Auth/types';
+import { FetchAuthSessionOptions } from '../Auth/types';
+import { debounceCallback } from '../../utils/debounceCallback';
 
-export const fetchAuthSession = (
-	options?: FetchAuthSessionOptions
-): Promise<AuthSession> => {
-	return fetchAuthSessionInternal(Amplify, options);
-};
+export const fetchAuthSession = debounceCallback(
+	(options?: FetchAuthSessionOptions) => {
+		return fetchAuthSessionInternal(Amplify, options);
+	}
+);

packages/core/src/utils/debounceCallback.ts

@@ -0,0 +1,62 @@
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+import { throwError } from 'rxjs';
+
+/**
+ * Debounces concurrent sync calls
+ *
+ * @param callback - callback to be debounced.
+ * @returns - the return type of the callback
+ */
+// export const debounceCallback = <F extends (...args: any[]) => any>(
+// 	callback: F
+// ) => {
+// 	let counter: number = 0;
+// 	let inflightPromise: Promise<Awaited<ReturnType<F>>>;
+// 	return async (...args: Parameters<F>): Promise<Awaited<ReturnType<F>>> => {
+// 		if (counter === 0) {
+// 			inflightPromise = new Promise(async (resolve, reject) => {
+// 				try {
+// 					const result = await callback(...args);
+// 					resolve(result);
+// 				} catch (error) {
+// 					reject(error);
+// 				}
+// 			});
+// 		}
+// 		counter++;
+
+// 		try {
+// 			return await inflightPromise;
+// 		} finally {
+// 			counter--;
+// 		}
+// 	};
+// };
+
+export const debounceCallback = <F extends (...args: any[]) => any>(
+	callback: F
+) => {
+	let inflightPromise: Promise<Awaited<ReturnType<F>>> | undefined;
+	return async (...args: Parameters<F>): Promise<Awaited<ReturnType<F>>> => {
+		if (inflightPromise) return inflightPromise;
+
+		if (!inflightPromise) {
+			inflightPromise = new Promise(async (resolve, reject) => {
+				try {
+					const result = await callback(...args);
+					resolve(result);
+				} catch (error) {
+					reject(error);
+				}
+			});
+		}
+
+		try {
+			return await inflightPromise;
+		} finally {
+			inflightPromise = undefined;
+		}
+	};
+};

packages/datastore/src/sync/processors/subscription.ts

@@ -279,7 +279,7 @@ class SubscriptionProcessor {
 
 				try {
 					// retrieving current token info from Cognito UserPools
-					const session = await await fetchAuthSession();
+					const session = await fetchAuthSession();
 					oidcTokenPayload = session.tokens?.idToken?.payload;
 				} catch (err) {
 					// best effort to get jwt from Cognito