Revert Sticky Sessions (#7)

* Disable Sticky Sessions by Default

* Revert "Disable Sticky Sessions by Default"

This reverts commit 4af9351.

* Revert Sticky Sessions

* 0.0.7

Author: ploomiz

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@eppo/js-client-sdk",
-  "version": "0.0.6",
+  "version": "0.0.7",
   "description": "Eppo SDK for client-side JavaScript applications",
   "main": "dist/index.js",
   "files": [

src/eppo-client.spec.ts

@@ -168,12 +168,6 @@ describe('EppoClient E2E test', () => {
     );
   });
 
-  it('uses the same assignment during the session, even if it changes after local storage update', async () => {
-    expect(getInstance().getAssignment(sessionOverrideSubject, preloadedConfigExperiment)).toEqual(
-      'preloaded-config-variation',
-    );
-  });
-
   it('returns subject from overrides when enabled is true', () => {
     const experiment = 'experiment_5';
     window.localStorage.setItem(

src/eppo-client.ts

@@ -1,7 +1,7 @@
 import * as md5 from 'md5';
 
 import { IAssignmentEvent, IAssignmentLogger } from './assignment-logger';
-import { MAX_EVENT_QUEUE_SIZE, NULL_SENTINEL, SESSION_ASSIGNMENT_CONFIG_LOADED } from './constants';
+import { MAX_EVENT_QUEUE_SIZE } from './constants';
 import { IExperimentConfiguration } from './experiment/experiment-configuration';
 import { EppoLocalStorage } from './local-storage';
 import { Rule } from './rule';
@@ -50,30 +50,16 @@ export default class EppoClient implements IEppoClient {
   getAssignment(subjectKey: string, experimentKey: string, subjectAttributes = {}): string {
     validateNotBlank(subjectKey, 'Invalid argument: subjectKey cannot be blank');
     validateNotBlank(experimentKey, 'Invalid argument: experimentKey cannot be blank');
-    // If getAssignment was called when the latest configuration were still being downloaded
-    // use the old assignment for the remainder of the session to avoid a flickering effect;
-    // we don't want a subject to switch between 2 variations during the same session.
-    const sessionOverrideKey = `${subjectKey}-${experimentKey}-session-override`;
-    const sessionOverride = this.sessionStorage.get(sessionOverrideKey);
-    if (sessionOverride) {
-      if (sessionOverride === NULL_SENTINEL) {
-        return null;
-      }
-      this.logAssignment(experimentKey, sessionOverride, subjectKey, subjectAttributes);
-      return sessionOverride;
-    }
     const experimentConfig = this.configurationStore.get<IExperimentConfiguration>(experimentKey);
     const allowListOverride = this.getSubjectVariationOverride(subjectKey, experimentConfig);
     if (allowListOverride) {
-      this.setSessionOverrideIfLoadingConfigurations(sessionOverrideKey, allowListOverride);
       return allowListOverride;
     }
     if (
       !experimentConfig?.enabled ||
       !this.subjectAttributesSatisfyRules(subjectAttributes, experimentConfig.rules) ||
       !this.isInExperimentSample(subjectKey, experimentKey, experimentConfig)
     ) {
-      this.setSessionOverrideIfLoadingConfigurations(sessionOverrideKey, NULL_SENTINEL);
       return null;
     }
     const { variations, subjectShards } = experimentConfig;
@@ -82,7 +68,6 @@ export default class EppoClient implements IEppoClient {
       isShardInRange(shard, variation.shardRange),
     ).name;
     this.logAssignment(experimentKey, assignedVariation, subjectKey, subjectAttributes);
-    this.setSessionOverrideIfLoadingConfigurations(sessionOverrideKey, assignedVariation);
     return assignedVariation;
   }
 
@@ -129,12 +114,6 @@ export default class EppoClient implements IEppoClient {
     }
   }
 
-  private setSessionOverrideIfLoadingConfigurations(overrideKey: string, assignmentValue: string) {
-    if (this.sessionStorage.get(SESSION_ASSIGNMENT_CONFIG_LOADED) !== 'true') {
-      this.sessionStorage.set(overrideKey, assignmentValue);
-    }
-  }
-
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   private subjectAttributesSatisfyRules(subjectAttributes?: Record<string, any>, rules?: Rule[]) {
     if (!rules || rules.length === 0) {

src/index.ts

@@ -57,10 +57,8 @@ export async function init(config: IClientConfig): Promise<IEppoClient> {
   });
   EppoClient.instance.setLogger(config.assignmentLogger);
   const configurationRequestor = new ExperimentConfigurationRequestor(localStorage, httpClient);
-  if (sessionStorage.get(SESSION_ASSIGNMENT_CONFIG_LOADED) !== 'true') {
-    await configurationRequestor.fetchAndStoreConfigurations();
-    sessionStorage.set(SESSION_ASSIGNMENT_CONFIG_LOADED, 'true');
-  }
+  await configurationRequestor.fetchAndStoreConfigurations();
+  sessionStorage.set(SESSION_ASSIGNMENT_CONFIG_LOADED, 'true');
   return EppoClient.instance;
 }