Merge pull request #445 from splitio/readiness-fix-ready-promise

[Readiness] Deprecate `ready` promise and replace with `whenReady` and `whenReadyFromCache`

Author: EmilianoSanchez

CHANGES.txt

@@ -1,4 +1,5 @@
 2.8.0 (October XX, 2025)
+ - Added `client.whenReady()` and `client.whenReadyFromCache()` methods to replace the deprecated `client.ready()` method, which has an issue causing the returned promise to hang when using async/await syntax if it was rejected.
  - Updated the SDK_READY_FROM_CACHE event to be emitted alongside the SDK_READY event if it hasn’t already been emitted.
 
 2.7.1 (October 8, 2025)

src/logger/messages/warn.ts

@@ -15,7 +15,7 @@ export const codesWarn: [number, string][] = codesError.concat([
   [c.SUBMITTERS_PUSH_RETRY, c.LOG_PREFIX_SYNC_SUBMITTERS + 'Failed to push %s, keeping data to retry on next iteration. Reason: %s.'],
   // client status
   [c.CLIENT_NOT_READY_FROM_CACHE, '%s: the SDK is not ready to evaluate. Results may be incorrect%s. Make sure to wait for SDK readiness before using this method.'],
-  [c.CLIENT_NO_LISTENER, 'No listeners for SDK Readiness detected. Incorrect control treatments could have been logged if you called getTreatment/s while the SDK was not yet ready.'],
+  [c.CLIENT_NO_LISTENER, 'No listeners for SDK_READY event detected. Incorrect control treatments could have been logged if you called getTreatment/s while the SDK was not yet synchronized with the backend.'],
   // input validation
   [c.WARN_SETTING_NULL, '%s: Property "%s" is of invalid type. Setting value to null.'],
   [c.WARN_TRIMMING_PROPERTIES, '%s: more than 300 properties were provided. Some of them will be trimmed when processed.'],

src/readiness/__tests__/sdkReadinessManager.spec.ts

@@ -1,11 +1,12 @@
 // @ts-nocheck
 import { loggerMock } from '../../logger/__tests__/sdkLogger.mock';
 import SplitIO from '../../../types/splitio';
-import { SDK_READY, SDK_READY_FROM_CACHE, SDK_READY_TIMED_OUT, SDK_UPDATE } from '../constants';
+import { SDK_READY, SDK_READY_FROM_CACHE, SDK_READY_TIMED_OUT, SDK_UPDATE, SDK_SPLITS_ARRIVED, SDK_SEGMENTS_ARRIVED, SDK_SPLITS_CACHE_LOADED } from '../constants';
 import { sdkReadinessManagerFactory } from '../sdkReadinessManager';
 import { IReadinessManager } from '../types';
 import { ERROR_CLIENT_LISTENER, CLIENT_READY_FROM_CACHE, CLIENT_READY, CLIENT_NO_LISTENER } from '../../logger/constants';
 import { fullSettings } from '../../utils/settingsValidation/__tests__/settings.mocks';
+import { EventEmitter } from '../../utils/MinEvents';
 
 const EventEmitterMock = jest.fn(() => ({
   on: jest.fn(),
@@ -19,24 +20,37 @@ const EventEmitterMock = jest.fn(() => ({
 
 // Makes readinessManager emit SDK_READY & update isReady flag
 function emitReadyEvent(readinessManager: IReadinessManager) {
+  if (readinessManager.gate instanceof EventEmitter) {
+    readinessManager.splits.emit(SDK_SPLITS_ARRIVED);
+    readinessManager.segments.emit(SDK_SEGMENTS_ARRIVED);
+    return;
+  }
+
   readinessManager.splits.once.mock.calls[0][1]();
   readinessManager.splits.on.mock.calls[0][1]();
   readinessManager.segments.once.mock.calls[0][1]();
   readinessManager.segments.on.mock.calls[0][1]();
   readinessManager.gate.once.mock.calls[0][1]();
+  if (readinessManager.gate.once.mock.calls[3]) readinessManager.gate.once.mock.calls[3][1](); // whenReady promise
 }
 
 const timeoutErrorMessage = 'Split SDK emitted SDK_READY_TIMED_OUT event.';
 
 // Makes readinessManager emit SDK_READY_TIMED_OUT & update hasTimedout flag
 function emitTimeoutEvent(readinessManager: IReadinessManager) {
+  if (readinessManager.gate instanceof EventEmitter) {
+    readinessManager.timeout();
+    return;
+  }
+
   readinessManager.gate.once.mock.calls[1][1](timeoutErrorMessage);
   readinessManager.hasTimedout = () => true;
+  if (readinessManager.gate.once.mock.calls[4]) readinessManager.gate.once.mock.calls[4][1](timeoutErrorMessage); // whenReady promise
 }
 
 describe('SDK Readiness Manager - Event emitter', () => {
 
-  afterEach(() => { loggerMock.mockClear(); });
+  beforeEach(() => { loggerMock.mockClear(); });
 
   test('Providing the gate object to get the SDK status interface that manages events', () => {
     expect(typeof sdkReadinessManagerFactory).toBe('function'); // The module exposes a function.
@@ -50,7 +64,8 @@ describe('SDK Readiness Manager - Event emitter', () => {
       expect(sdkStatus[propName]).toBeTruthy(); // The sdkStatus exposes all minimal EventEmitter functionality.
     });
 
-    expect(typeof sdkStatus.ready).toBe('function'); // The sdkStatus exposes a .ready() function.
+    expect(typeof sdkStatus.whenReady).toBe('function'); // The sdkStatus exposes a .whenReady() function.
+    expect(typeof sdkStatus.whenReadyFromCache).toBe('function'); // The sdkStatus exposes a .whenReadyFromCache() function.
     expect(typeof sdkStatus.__getStatus).toBe('function'); // The sdkStatus exposes a .__getStatus() function.
     expect(sdkStatus.__getStatus()).toEqual({
       isReady: false, isReadyFromCache: false, isTimedout: false, hasTimedout: false, isDestroyed: false, isOperational: false, lastUpdate: 0
@@ -67,9 +82,9 @@ describe('SDK Readiness Manager - Event emitter', () => {
     const sdkReadyResolvePromiseCall = gateMock.once.mock.calls[0];
     const sdkReadyRejectPromiseCall = gateMock.once.mock.calls[1];
     const sdkReadyFromCacheListenersCheckCall = gateMock.once.mock.calls[2];
-    expect(sdkReadyResolvePromiseCall[0]).toBe(SDK_READY); // A one time only subscription is on the SDK_READY event, for resolving the full blown ready promise and to check for callbacks warning.
-    expect(sdkReadyRejectPromiseCall[0]).toBe(SDK_READY_TIMED_OUT); // A one time only subscription is also on the SDK_READY_TIMED_OUT event, for rejecting the full blown ready promise.
-    expect(sdkReadyFromCacheListenersCheckCall[0]).toBe(SDK_READY_FROM_CACHE); // A one time only subscription is on the SDK_READY_FROM_CACHE event, to log the event and update internal state.
+    expect(sdkReadyResolvePromiseCall[0]).toBe(SDK_READY); // A one time only subscription is on the SDK_READY event
+    expect(sdkReadyRejectPromiseCall[0]).toBe(SDK_READY_TIMED_OUT); // A one time only subscription is also on the SDK_READY_TIMED_OUT event
+    expect(sdkReadyFromCacheListenersCheckCall[0]).toBe(SDK_READY_FROM_CACHE); // A one time only subscription is on the SDK_READY_FROM_CACHE event
 
     expect(gateMock.on).toBeCalledTimes(2); // It should also add two persistent listeners
 
@@ -98,7 +113,7 @@ describe('SDK Readiness Manager - Event emitter', () => {
 
     emitReadyEvent(sdkReadinessManager.readinessManager);
 
-    expect(loggerMock.warn).toBeCalledTimes(1); // If the SDK_READY event fires and we have no callbacks for it (neither event nor ready promise) we get a warning.
+    expect(loggerMock.warn).toBeCalledTimes(1); // If the SDK_READY event fires and we have no callbacks for it (neither event nor whenReady promise) we get a warning.
     expect(loggerMock.warn).toBeCalledWith(CLIENT_NO_LISTENER); // Telling us there were no listeners and evaluations before this point may have been incorrect.
 
     expect(loggerMock.info).toBeCalledTimes(1); // If the SDK_READY event fires, we get a info message.
@@ -199,77 +214,98 @@ describe('SDK Readiness Manager - Event emitter', () => {
   });
 });
 
-describe('SDK Readiness Manager - Ready promise', () => {
+describe('SDK Readiness Manager - Promises', () => {
 
-  test('.ready() promise behavior for clients', async () => {
-    const sdkReadinessManager = sdkReadinessManagerFactory(EventEmitterMock, fullSettings);
+  test('.whenReady() and .whenReadyFromCache() promises resolves when SDK_READY is emitted', async () => {
+    const sdkReadinessManager = sdkReadinessManagerFactory(EventEmitter, fullSettings);
+
+    // make the SDK ready from cache
+    sdkReadinessManager.readinessManager.splits.emit(SDK_SPLITS_CACHE_LOADED);
+    expect(await sdkReadinessManager.sdkStatus.whenReadyFromCache()).toBe(false);
 
-    const ready = sdkReadinessManager.sdkStatus.ready();
-    expect(ready instanceof Promise).toBe(true); // It should return a promise.
+    // validate error log for SDK_READY_FROM_CACHE
+    expect(loggerMock.error).not.toBeCalled();
+    sdkReadinessManager.readinessManager.gate.on(SDK_READY_FROM_CACHE, () => {});
+    expect(loggerMock.error).toBeCalledWith(ERROR_CLIENT_LISTENER, ['SDK_READY_FROM_CACHE']);
 
-    // make the SDK "ready"
+    const readyFromCache = sdkReadinessManager.sdkStatus.whenReadyFromCache();
+    const ready = sdkReadinessManager.sdkStatus.whenReady();
+
+    // make the SDK ready
     emitReadyEvent(sdkReadinessManager.readinessManager);
+    expect(await sdkReadinessManager.sdkStatus.whenReadyFromCache()).toBe(true);
 
     let testPassedCount = 0;
-    await ready.then(
-      () => {
-        expect('It should be a promise that will be resolved when the SDK is ready.');
-        testPassedCount++;
-      },
-      () => { throw new Error('It should be resolved on ready event, not rejected.'); }
-    );
+    function incTestPassedCount() { testPassedCount++; }
+    function throwTestFailed() { throw new Error('It should be resolved, not rejected.'); }
 
-    // any subsequent call to .ready() must be a resolved promise
-    await ready.then(
-      () => {
-        expect('A subsequent call should be a resolved promise.');
-        testPassedCount++;
-      },
-      () => { throw new Error('It should be resolved on ready event, not rejected.'); }
-    );
+    await readyFromCache.then(incTestPassedCount, throwTestFailed);
+    await ready.then(incTestPassedCount, throwTestFailed);
 
-    // control assertion. stubs already reset.
-    expect(testPassedCount).toBe(2);
+    // any subsequent call to .whenReady() and .whenReadyFromCache() must be a resolved promise
+    await sdkReadinessManager.sdkStatus.whenReady().then(incTestPassedCount, throwTestFailed);
+    await sdkReadinessManager.sdkStatus.whenReadyFromCache().then(incTestPassedCount, throwTestFailed);
 
-    const sdkReadinessManagerForTimedout = sdkReadinessManagerFactory(EventEmitterMock, fullSettings);
+    expect(testPassedCount).toBe(4);
+  });
 
-    const readyForTimeout = sdkReadinessManagerForTimedout.sdkStatus.ready();
+  test('.whenReady() and .whenReadyFromCache() promises reject when SDK_READY_TIMED_OUT is emitted before SDK_READY', async () => {
+    const sdkReadinessManagerForTimedout = sdkReadinessManagerFactory(EventEmitter, fullSettings);
 
-    emitTimeoutEvent(sdkReadinessManagerForTimedout.readinessManager); // make the SDK "timed out"
+    const readyFromCacheForTimeout = sdkReadinessManagerForTimedout.sdkStatus.whenReadyFromCache();
+    const readyForTimeout = sdkReadinessManagerForTimedout.sdkStatus.whenReady();
 
-    await readyForTimeout.then(
-      () => { throw new Error('It should be a promise that was rejected on SDK_READY_TIMED_OUT, not resolved.'); },
-      () => {
-        expect('It should be a promise that will be rejected when the SDK is timed out.');
-        testPassedCount++;
-      }
-    );
+    emitTimeoutEvent(sdkReadinessManagerForTimedout.readinessManager); // make the SDK timeout
 
-    // any subsequent call to .ready() must be a rejected promise
-    await readyForTimeout.then(
-      () => { throw new Error('It should be a promise that was rejected on SDK_READY_TIMED_OUT, not resolved.'); },
-      () => {
-        expect('A subsequent call should be a rejected promise.');
-        testPassedCount++;
-      }
-    );
+    let testPassedCount = 0;
+    function incTestPassedCount() { testPassedCount++; }
+    function throwTestFailed() { throw new Error('It should rejected, not resolved.'); }
+
+    await readyFromCacheForTimeout.then(throwTestFailed,incTestPassedCount);
+    await readyForTimeout.then(throwTestFailed,incTestPassedCount);
 
-    // make the SDK "ready"
+    // any subsequent call to .whenReady() and .whenReadyFromCache() must be a rejected promise until the SDK is ready
+    await sdkReadinessManagerForTimedout.sdkStatus.whenReadyFromCache().then(throwTestFailed,incTestPassedCount);
+    await sdkReadinessManagerForTimedout.sdkStatus.whenReady().then(throwTestFailed,incTestPassedCount);
+
+    // make the SDK ready
     emitReadyEvent(sdkReadinessManagerForTimedout.readinessManager);
 
-    // once SDK_READY, `.ready()` returns a resolved promise
-    await ready.then(
-      () => {
-        expect('It should be a resolved promise when the SDK is ready, even after an SDK timeout.');
-        loggerMock.mockClear();
-        testPassedCount++;
-        expect(testPassedCount).toBe(5);
-      },
-      () => { throw new Error('It should be resolved on ready event, not rejected.'); }
-    );
+    // once SDK_READY, `.whenReady()` returns a resolved promise
+    await sdkReadinessManagerForTimedout.sdkStatus.whenReady().then(incTestPassedCount, throwTestFailed);
+    await sdkReadinessManagerForTimedout.sdkStatus.whenReadyFromCache().then(incTestPassedCount, throwTestFailed);
+
+    expect(testPassedCount).toBe(6);
+  });
+
+  test('whenReady promise counts as an SDK_READY listener', (done) => {
+    let sdkReadinessManager = sdkReadinessManagerFactory(EventEmitter, fullSettings);
+
+    emitReadyEvent(sdkReadinessManager.readinessManager);
+
+    expect(loggerMock.warn).toBeCalledWith(CLIENT_NO_LISTENER); // We should get a warning if the SDK get's ready before calling the whenReady method or attaching a listener to the ready event
+    loggerMock.warn.mockClear();
+
+    sdkReadinessManager = sdkReadinessManagerFactory(EventEmitter, fullSettings);
+    sdkReadinessManager.sdkStatus.whenReady().then(() => {
+      expect('whenReady promise is resolved when the gate emits SDK_READY.');
+      done();
+    }, () => {
+      throw new Error('This should not be called as the promise is being resolved.');
+    });
+
+    emitReadyEvent(sdkReadinessManager.readinessManager);
+
+    expect(loggerMock.warn).not.toBeCalled(); // But if we have a listener or call the whenReady method, we get no warnings.
   });
+});
+
+// @TODO: remove in next major
+describe('SDK Readiness Manager - Ready promise', () => {
+
+  beforeEach(() => { loggerMock.mockClear(); });
 
-  test('Full blown ready promise count as a callback and resolves on SDK_READY', (done) => {
+  test('ready promise count as a callback and resolves on SDK_READY', (done) => {
     const sdkReadinessManager = sdkReadinessManagerFactory(EventEmitterMock, fullSettings);
     const readyPromise = sdkReadinessManager.sdkStatus.ready();
 

src/readiness/readinessManager.ts

@@ -90,7 +90,7 @@ export function readinessManagerFactory(
     if (!isReady && !isDestroyed) {
       try {
         syncLastUpdate();
-        gate.emit(SDK_READY_FROM_CACHE);
+        gate.emit(SDK_READY_FROM_CACHE, isReady);
       } catch (e) {
         // throws user callback exceptions in next tick
         setTimeout(() => { throw e; }, 0);
@@ -116,7 +116,7 @@ export function readinessManagerFactory(
           syncLastUpdate();
           if (!isReadyFromCache) {
             isReadyFromCache = true;
-            gate.emit(SDK_READY_FROM_CACHE);
+            gate.emit(SDK_READY_FROM_CACHE, isReady);
           }
           gate.emit(SDK_READY);
         } catch (e) {

src/readiness/sdkReadinessManager.ts

@@ -9,6 +9,7 @@ import { ERROR_CLIENT_LISTENER, CLIENT_READY_FROM_CACHE, CLIENT_READY, CLIENT_NO
 
 const NEW_LISTENER_EVENT = 'newListener';
 const REMOVE_LISTENER_EVENT = 'removeListener';
+const TIMEOUT_ERROR = new Error(SDK_READY_TIMED_OUT);
 
 /**
  * SdkReadinessManager factory, which provides the public status API of SDK clients and manager: ready promise, readiness event emitter and constants (SDK_READY, etc).
@@ -38,6 +39,8 @@ export function sdkReadinessManagerFactory(
       } else if (event === SDK_READY) {
         readyCbCount++;
       }
+    } else if (event === SDK_READY_FROM_CACHE && readinessManager.isReadyFromCache()) {
+      log.error(ERROR_CLIENT_LISTENER, ['SDK_READY_FROM_CACHE']);
     }
   });
 
@@ -93,6 +96,7 @@ export function sdkReadinessManagerFactory(
           SDK_READY_TIMED_OUT,
         },
 
+        // @TODO: remove in next major
         ready() {
           if (readinessManager.hasTimedout()) {
             if (!readinessManager.isReady()) {
@@ -104,6 +108,32 @@ export function sdkReadinessManagerFactory(
           return readyPromise;
         },
 
+        whenReady() {
+          return new Promise<void>((resolve, reject) => {
+            if (readinessManager.isReady()) {
+              resolve();
+            } else if (readinessManager.hasTimedout()) {
+              reject(TIMEOUT_ERROR);
+            } else {
+              readinessManager.gate.once(SDK_READY, resolve);
+              readinessManager.gate.once(SDK_READY_TIMED_OUT, () => reject(TIMEOUT_ERROR));
+            }
+          });
+        },
+
+        whenReadyFromCache() {
+          return new Promise<boolean>((resolve, reject) => {
+            if (readinessManager.isReadyFromCache()) {
+              resolve(readinessManager.isReady());
+            } else if (readinessManager.hasTimedout()) {
+              reject(TIMEOUT_ERROR);
+            } else {
+              readinessManager.gate.once(SDK_READY_FROM_CACHE, () => resolve(readinessManager.isReady()));
+              readinessManager.gate.once(SDK_READY_TIMED_OUT, () => reject(TIMEOUT_ERROR));
+            }
+          });
+        },
+
         __getStatus() {
           return {
             isReady: readinessManager.isReady(),