Respect targeting in persistent evaluation (#503)

Grammarly needs to allow targeting rules to still apply for persisted evaluations. Currently, even if a user no longer passes targeting, we return the persisted evaluation.
I added an option to `getExperiment` and `getLayer` that allows you to respect the targeting rules of an experiment even for persisted evaluations

Kong: https://app.graphite.dev/github/pr/statsig-io/kong/2655

src/ConfigSpec.ts

@@ -82,6 +82,10 @@ export class ConfigRule {
     });
     return conditions;
   }
+
+  isTargetingRule(): boolean {
+    return this.id === 'inlineTargetingRules' || this.id === 'targetingGate';
+  }
 }
 
 export class ConfigCondition {

src/Evaluator.ts

@@ -672,7 +672,8 @@ export default class Evaluator {
   }
 
   _evalConfig(ctx: EvaluationContext): ConfigEvaluation {
-    const { user, spec, userPersistedValues } = ctx;
+    const { user, spec, userPersistedValues, persistentAssignmentOptions } =
+      ctx;
     if (userPersistedValues == null || !spec.isActive) {
       this.persistentStore.delete(user, spec.idType, spec.name);
       return this._evalSpec(ctx);
@@ -687,7 +688,14 @@ export default class Evaluator {
       : null;
 
     if (stickyEvaluation) {
-      return stickyEvaluation;
+      if (persistentAssignmentOptions?.enforceTargeting) {
+        const passesTargeting = this._evalTargeting(ctx);
+        if (passesTargeting) {
+          return stickyEvaluation;
+        }
+      } else {
+        return stickyEvaluation;
+      }
     }
 
     const evaluation = this._evalSpec(ctx);
@@ -700,7 +708,8 @@ export default class Evaluator {
   }
 
   _evalLayer(ctx: EvaluationContext): ConfigEvaluation {
-    const { user, spec, userPersistedValues } = ctx;
+    const { user, spec, userPersistedValues, persistentAssignmentOptions } =
+      ctx;
     if (!userPersistedValues) {
       this.persistentStore.delete(user, spec.idType, spec.name);
       return this._evalSpec(ctx);
@@ -714,31 +723,49 @@ export default class Evaluator {
         )
       : null;
 
-    const isAllocatedExperimentActive = (evaluation: ConfigEvaluation) =>
-      this._isExperimentActive(
-        evaluation.config_delegate
-          ? this.store.getConfig(evaluation.config_delegate)
-          : null,
-      );
-
     if (stickyEvaluation) {
-      if (isAllocatedExperimentActive(stickyEvaluation)) {
-        return stickyEvaluation;
+      const delegateSpec = stickyEvaluation.config_delegate
+        ? this.store.getConfig(stickyEvaluation.config_delegate)
+        : null;
+      if (delegateSpec && delegateSpec.isActive) {
+        if (persistentAssignmentOptions?.enforceTargeting) {
+          const passesTargeting = this._evalTargeting(ctx, delegateSpec);
+          if (passesTargeting) {
+            return stickyEvaluation;
+          }
+        } else {
+          return stickyEvaluation;
+        }
       } else {
         this.persistentStore.delete(user, spec.idType, spec.name);
         return this._evalSpec(ctx);
       }
-    } else {
-      const evaluation = this._evalSpec(ctx);
-      if (isAllocatedExperimentActive(evaluation)) {
-        if (evaluation.is_experiment_group) {
-          this.persistentStore.save(user, spec.idType, spec.name, evaluation);
-        }
-      } else {
-        this.persistentStore.delete(user, spec.idType, spec.name);
+    }
+
+    const evaluation = this._evalSpec(ctx);
+    const delegateSpec = evaluation.config_delegate
+      ? this.store.getConfig(evaluation.config_delegate)
+      : null;
+    if (delegateSpec && delegateSpec.isActive) {
+      if (evaluation.is_experiment_group) {
+        this.persistentStore.save(user, spec.idType, spec.name, evaluation);
       }
-      return evaluation;
+    } else {
+      this.persistentStore.delete(user, spec.idType, spec.name);
     }
+    return evaluation;
+  }
+
+  _evalTargeting(ctx: EvaluationContext, delegateSpec?: ConfigSpec): boolean {
+    return (
+      this._evalSpec(
+        EvaluationContext.get(ctx.getRequestContext(), {
+          user: ctx.user,
+          spec: delegateSpec ?? ctx.spec,
+          onlyEvaluateTargeting: true,
+        }),
+      ).value === false
+    ); // Fail evaluation means to pass targeting (fall through logic)
   }
 
   _evalSpec(ctx: EvaluationContext): ConfigEvaluation {
@@ -769,9 +796,16 @@ export default class Evaluator {
       );
     }
 
+    let rules = config.rules;
+    if (ctx.onlyEvaluateTargeting) {
+      rules = config.rules.filter((rule) => rule.isTargetingRule());
+      if (rules.length === 0) {
+        return new ConfigEvaluation(true);
+      }
+    }
+
     let secondary_exposures: SecondaryExposure[] = [];
-    for (let i = 0; i < config.rules.length; i++) {
-      const rule = config.rules[i];
+    for (const rule of rules) {
       const ruleResult = this._evalRule(user, rule, ctx);
       if (ruleResult.unsupported) {
         return ConfigEvaluation.unsupported(

src/StatsigOptions.ts

@@ -237,10 +237,21 @@ function normalizeUrl(url: string | null): string | null {
   return url && url.endsWith('/') ? url.slice(0, -1) : url;
 }
 
+export type PersistentAssignmentOptions = {
+  /* Whether or not to enforce targeting rules before assigning persisted values */
+  enforceTargeting?: boolean;
+};
+
 export type GetExperimentOptions = {
+  /* Persisted values to use for experiment assignment */
   userPersistedValues?: UserPersistedValues | null;
+  /* Additional options for using persistent assignment */
+  persistentAssignmentOptions?: PersistentAssignmentOptions;
 };
 
 export type GetLayerOptions = {
+  /* Persisted values to use for layer assignment */
   userPersistedValues?: UserPersistedValues | null;
+  /* Additional options for using persistent assignment */
+  persistentAssignmentOptions?: PersistentAssignmentOptions;
 };

src/StatsigServer.ts

@@ -325,6 +325,7 @@ export default class StatsigServer {
         caller: 'getExperiment',
         configName: experimentName,
         userPersistedValues: options?.userPersistedValues,
+        persistentAssignmentOptions: options?.persistentAssignmentOptions,
       }),
     );
   }
@@ -342,6 +343,7 @@ export default class StatsigServer {
         caller: 'getExperimentWithExposureLoggingDisabled',
         configName: experimentName,
         userPersistedValues: options?.userPersistedValues,
+        persistentAssignmentOptions: options?.persistentAssignmentOptions,
       }),
     );
   }
@@ -402,6 +404,7 @@ export default class StatsigServer {
         caller: 'getLayer',
         configName: layerName,
         userPersistedValues: options?.userPersistedValues,
+        persistentAssignmentOptions: options?.persistentAssignmentOptions,
       }),
     );
   }
@@ -419,6 +422,7 @@ export default class StatsigServer {
         caller: 'getLayerWithExposureLoggingDisabled',
         configName: layerName,
         userPersistedValues: options?.userPersistedValues,
+        persistentAssignmentOptions: options?.persistentAssignmentOptions,
       }),
     );
   }

src/utils/StatsigContext.ts

@@ -4,6 +4,7 @@ import {
   InitializationSource,
 } from '../InitializationDetails';
 import { UserPersistedValues } from '../interfaces/IUserPersistentStorage';
+import { PersistentAssignmentOptions } from '../StatsigOptions';
 import { StatsigUser } from '../StatsigUser';
 
 type RequestContext = {
@@ -17,6 +18,7 @@ type RequestContext = {
   user?: StatsigUser;
   spec?: ConfigSpec;
   userPersistedValues?: UserPersistedValues | null;
+  persistentAssignmentOptions?: PersistentAssignmentOptions;
 };
 
 export class StatsigContext {
@@ -28,6 +30,7 @@ export class StatsigContext {
   readonly hash?: string;
   readonly bypassDedupe?: boolean;
   readonly userPersistedValues?: UserPersistedValues | null;
+  readonly persistentAssignmentOptions?: PersistentAssignmentOptions;
 
   protected constructor(protected ctx: RequestContext) {
     this.startTime = Date.now();
@@ -38,6 +41,7 @@ export class StatsigContext {
     this.hash = ctx.clientKey;
     this.bypassDedupe = ctx.bypassDedupe;
     this.userPersistedValues = ctx.userPersistedValues;
+    this.persistentAssignmentOptions = ctx.persistentAssignmentOptions;
   }
 
   // Create a new context to avoid modifying context up the stack
@@ -64,17 +68,20 @@ export class EvaluationContext extends StatsigContext {
   readonly user: StatsigUser;
   readonly spec: ConfigSpec;
   readonly targetAppID?: string;
+  readonly onlyEvaluateTargeting?: boolean;
 
   protected constructor(
     ctx: RequestContext,
     user: StatsigUser,
     spec: ConfigSpec,
     targetAppID?: string,
+    onlyEvaluateTargeting?: boolean,
   ) {
     super(ctx);
     this.user = user;
     this.spec = spec;
     this.targetAppID = targetAppID;
+    this.onlyEvaluateTargeting = onlyEvaluateTargeting;
   }
 
   public static new(
@@ -90,22 +97,15 @@ export class EvaluationContext extends StatsigContext {
       user: StatsigUser;
       spec: ConfigSpec;
       targetAppID?: string;
+      onlyEvaluateTargeting?: boolean;
     },
   ): EvaluationContext {
     return new EvaluationContext(
       ctx,
       evalCtx.user,
       evalCtx.spec,
       evalCtx.targetAppID,
-    );
-  }
-
-  public withTargetAppID(targetAppID: string): EvaluationContext {
-    return new EvaluationContext(
-      this.getRequestContext(),
-      this.user,
-      this.spec,
-      targetAppID,
+      evalCtx.onlyEvaluateTargeting,
     );
   }
 }