feat: IConfiguration interface for config access in EppoClient (#222)

* chore: rename configuration.ts to configuration-wire-types.ts

* chore: deprecate fetchFlagConfigurations in favour of startPolling

* feat: Wrap configuration store access in new Configuration object

* feat: ConfigurationRequestor.getConfiguration

* chore: delegate isObfuscated check to i-config

* chore: delegate getFlagKeys to i-config

* chore: delegate getFlagConfigurations to i-config

* chore: delegate getFlag->getNormalizedFlag and evalDetails method to use i-config

* fix: point default config at other config stores

* chore: remove findBanditByVariation and delegate to i-config

* chore: remove getBandit and delegate to i-config

* feat: i-config.isInitialized

* chore: remove getConfigDetails and delegate to i-config

* feat: getters for other config stores and some renaming

* chore: delegate banditVariations.get to i-config

* move flag config expired check to config requestor

* v4.11.0

* chore: drop unimplemented and add specific string types

* chore: rename new config file to make a nicer diff

* chore:lint

* chore: take TODO

* chore: don't duplicate code

* comments

Author: typotter

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@eppo/js-client-sdk-common",
-  "version": "4.10.0",
+  "version": "4.11.0",
   "description": "Common library for Eppo JavaScript SDKs (web, react native, and node)",
   "main": "dist/index.js",
   "files": [

src/client/eppo-client-with-bandits.spec.ts

@@ -12,13 +12,13 @@ import ApiEndpoints from '../api-endpoints';
 import { IAssignmentEvent, IAssignmentLogger } from '../assignment-logger';
 import { BanditEvaluation, BanditEvaluator } from '../bandit-evaluator';
 import { IBanditEvent, IBanditLogger } from '../bandit-logger';
+import ConfigurationRequestor from '../configuration-requestor';
+import { MemoryOnlyConfigurationStore } from '../configuration-store/memory.store';
 import {
   IConfigurationWire,
   IPrecomputedConfiguration,
   IObfuscatedPrecomputedConfigurationResponse,
-} from '../configuration';
-import ConfigurationRequestor from '../configuration-requestor';
-import { MemoryOnlyConfigurationStore } from '../configuration-store/memory.store';
+} from '../configuration-wire-types';
 import { Evaluator, FlagEvaluation } from '../evaluator';
 import {
   AllocationEvaluationCode,

src/client/eppo-client.spec.ts

@@ -15,14 +15,14 @@ import {
 } from '../../test/testHelpers';
 import { IAssignmentLogger } from '../assignment-logger';
 import { AssignmentCache } from '../cache/abstract-assignment-cache';
+import { IConfigurationStore } from '../configuration-store/configuration-store';
+import { MemoryOnlyConfigurationStore } from '../configuration-store/memory.store';
 import {
   IConfigurationWire,
   IObfuscatedPrecomputedConfigurationResponse,
   ObfuscatedPrecomputedConfigurationResponse,
-} from '../configuration';
-import { IConfigurationStore } from '../configuration-store/configuration-store';
-import { MemoryOnlyConfigurationStore } from '../configuration-store/memory.store';
-import { DEFAULT_POLL_INTERVAL_MS, MAX_EVENT_QUEUE_SIZE, POLL_JITTER_PCT } from '../constants';
+} from '../configuration-wire-types';
+import { MAX_EVENT_QUEUE_SIZE, DEFAULT_POLL_INTERVAL_MS, POLL_JITTER_PCT } from '../constants';
 import { decodePrecomputedFlag } from '../decoding';
 import { Flag, ObfuscatedFlag, VariationType, FormatEnum, Variation } from '../interfaces';
 import { getMD5Hash } from '../obfuscation';

src/client/eppo-client.ts

@@ -14,20 +14,19 @@ import { AssignmentCache } from '../cache/abstract-assignment-cache';
 import { LRUInMemoryAssignmentCache } from '../cache/lru-in-memory-assignment-cache';
 import { NonExpiringInMemoryAssignmentCache } from '../cache/non-expiring-in-memory-cache-assignment';
 import { TLRUInMemoryAssignmentCache } from '../cache/tlru-in-memory-assignment-cache';
+import ConfigurationRequestor from '../configuration-requestor';
+import { IConfigurationStore, ISyncStore } from '../configuration-store/configuration-store';
 import {
   ConfigurationWireV1,
   IConfigurationWire,
   IPrecomputedConfiguration,
   PrecomputedConfiguration,
-} from '../configuration';
-import ConfigurationRequestor from '../configuration-requestor';
-import { IConfigurationStore, ISyncStore } from '../configuration-store/configuration-store';
+} from '../configuration-wire-types';
 import {
   DEFAULT_INITIAL_CONFIG_REQUEST_RETRIES,
   DEFAULT_POLL_CONFIG_REQUEST_RETRIES,
   DEFAULT_POLL_INTERVAL_MS,
   DEFAULT_REQUEST_TIMEOUT_MS,
-  OBFUSCATED_FORMATS,
 } from '../constants';
 import { decodeFlag } from '../decoding';
 import { EppoValue } from '../eppo_value';
@@ -41,13 +40,12 @@ import {
 } from '../flag-evaluation-details-builder';
 import { FlagEvaluationError } from '../flag-evaluation-error';
 import FetchHttpClient from '../http-client';
+import { IConfiguration, StoreBackedConfiguration } from '../i-configuration';
 import {
   BanditModelData,
   BanditParameters,
   BanditVariation,
-  ConfigDetails,
   Flag,
-  FormatEnum,
   IPrecomputedBandit,
   ObfuscatedFlag,
   PrecomputedFlag,
@@ -135,6 +133,7 @@ export default class EppoClient {
   private configObfuscatedCache?: boolean;
   private requestPoller?: IPoller;
   private readonly evaluator = new Evaluator();
+  private configurationRequestor?: ConfigurationRequestor;
 
   constructor({
     eventDispatcher = new NoOpEventDispatcher(),
@@ -164,6 +163,16 @@ export default class EppoClient {
     this.expectObfuscated = isObfuscated;
   }
 
+  private getConfiguration(): IConfiguration {
+    return this.configurationRequestor
+      ? this.configurationRequestor.getConfiguration()
+      : new StoreBackedConfiguration(
+          this.flagConfigurationStore,
+          this.banditVariationConfigurationStore,
+          this.banditModelConfigurationStore,
+        );
+  }
+
   private maybeWarnAboutObfuscationMismatch(configObfuscated: boolean) {
     // Don't warn again if we did on the last check.
     if (configObfuscated !== this.expectObfuscated && !this.obfuscationMismatchWarningIssued) {
@@ -177,11 +186,14 @@ export default class EppoClient {
     }
   }
 
-  private isObfuscated() {
+  /**
+   * This method delegates to the configuration to determine whether  it is obfuscated, then caches the actual
+   * obfuscation state and issues a warning if it hasn't already.
+   * This method can be removed with the next major update when the @deprecated setIsObfuscated is removed
+   */
+  private isObfuscated(config: IConfiguration) {
     if (this.configObfuscatedCache === undefined) {
-      this.configObfuscatedCache = OBFUSCATED_FORMATS.includes(
-        this.flagConfigurationStore.getFormat() ?? FormatEnum.SERVER,
-      );
+      this.configObfuscatedCache = config.isObfuscated();
     }
     this.maybeWarnAboutObfuscationMismatch(this.configObfuscatedCache);
     return this.configObfuscatedCache;
@@ -307,7 +319,7 @@ export default class EppoClient {
     );
 
     const pollingCallback = async () => {
-      if (await this.flagConfigurationStore.isExpired()) {
+      if (await configurationRequestor.isFlagConfigExpired()) {
         this.configObfuscatedCache = undefined;
         return configurationRequestor.fetchAndStoreConfigurations();
       }
@@ -624,13 +636,14 @@ export default class EppoClient {
     actions: BanditActions,
     defaultAction: string,
   ): string {
+    const config = this.getConfiguration();
     let result: string | null = null;
 
-    const flagBanditVariations = this.banditVariationConfigurationStore?.get(flagKey);
+    const flagBanditVariations = config.getFlagBanditVariations(flagKey);
     const banditKey = flagBanditVariations?.at(0)?.key;
 
     if (banditKey) {
-      const banditParameters = this.getBandit(banditKey);
+      const banditParameters = config.getBandit(banditKey);
       if (banditParameters) {
         const contextualSubjectAttributes = ensureContextualSubjectAttributes(subjectAttributes);
         const actionsWithContextualAttributes = ensureActionsWithContextualAttributes(actions);
@@ -653,11 +666,13 @@ export default class EppoClient {
     actions: BanditActions,
     defaultValue: string,
   ): IAssignmentDetails<string> {
+    const config = this.getConfiguration();
     let variation = defaultValue;
     let action: string | null = null;
 
     // Initialize with a generic evaluation details. This will mutate as the function progresses.
     let evaluationDetails: IFlagEvaluationDetails = this.newFlagEvaluationDetailsBuilder(
+      config,
       flagKey,
     ).buildForNoneResult(
       'ASSIGNMENT_ERROR',
@@ -681,7 +696,7 @@ export default class EppoClient {
       // Check if the assigned variation is an active bandit
       // Note: the reason for non-bandit assignments include the subject being bucketed into a non-bandit variation or
       // a rollout having been done.
-      const bandit = this.findBanditByVariation(flagKey, variation);
+      const bandit = config.getFlagVariationBandit(flagKey, variation);
 
       if (!bandit) {
         return { variation, action: null, evaluationDetails };
@@ -909,13 +924,14 @@ export default class EppoClient {
     subjectKey: string,
     subjectAttributes: Attributes = {},
   ): Record<FlagKey, PrecomputedFlag> {
-    const configDetails = this.getConfigDetails();
+    const config = this.getConfiguration();
+    const configDetails = config.getFlagConfigDetails();
     const flagKeys = this.getFlagKeys();
     const flags: Record<FlagKey, PrecomputedFlag> = {};
 
     // Evaluate all the enabled flags for the user
     flagKeys.forEach((flagKey) => {
-      const flag = this.getFlag(flagKey);
+      const flag = this.getNormalizedFlag(config, flagKey);
       if (!flag) {
         logger.debug(`${loggerPrefix} No assigned variation. Flag does not exist.`);
         return;
@@ -927,7 +943,7 @@ export default class EppoClient {
         configDetails,
         subjectKey,
         subjectAttributes,
-        this.isObfuscated(),
+        this.isObfuscated(config),
       );
 
       // allocationKey is set along with variation when there is a result. this check appeases typescript below
@@ -965,13 +981,15 @@ export default class EppoClient {
     banditActions: Record<FlagKey, BanditActions> = {},
     salt?: string,
   ): string {
-    const configDetails = this.getConfigDetails();
+    const config = this.getConfiguration();
+    const configDetails = config.getFlagConfigDetails();
 
     const subjectContextualAttributes = ensureContextualSubjectAttributes(subjectAttributes);
     const subjectFlatAttributes = ensureNonContextualSubjectAttributes(subjectAttributes);
     const flags = this.getAllAssignments(subjectKey, subjectFlatAttributes);
 
     const bandits = this.computeBanditsForFlags(
+      config,
       subjectKey,
       subjectContextualAttributes,
       banditActions,
@@ -1011,8 +1029,9 @@ export default class EppoClient {
   ): FlagEvaluation {
     validateNotBlank(subjectKey, 'Invalid argument: subjectKey cannot be blank');
     validateNotBlank(flagKey, 'Invalid argument: flagKey cannot be blank');
+    const config = this.getConfiguration();
 
-    const flagEvaluationDetailsBuilder = this.newFlagEvaluationDetailsBuilder(flagKey);
+    const flagEvaluationDetailsBuilder = this.newFlagEvaluationDetailsBuilder(config, flagKey);
     const overrideVariation = this.overrideStore?.get(flagKey);
     if (overrideVariation) {
       return overrideResult(
@@ -1024,8 +1043,8 @@ export default class EppoClient {
       );
     }
 
-    const configDetails = this.getConfigDetails();
-    const flag = this.getFlag(flagKey);
+    const configDetails = config.getFlagConfigDetails();
+    const flag = this.getNormalizedFlag(config, flagKey);
 
     if (flag === null) {
       logger.warn(`${loggerPrefix} No assigned variation. Flag not found: ${flagKey}`);
@@ -1077,7 +1096,7 @@ export default class EppoClient {
       );
     }
 
-    const isObfuscated = this.isObfuscated();
+    const isObfuscated = this.isObfuscated(config);
     const result = this.evaluator.evaluateFlag(
       flag,
       configDetails,
@@ -1114,9 +1133,12 @@ export default class EppoClient {
     });
   }
 
-  private newFlagEvaluationDetailsBuilder(flagKey: string): FlagEvaluationDetailsBuilder {
-    const flag = this.getFlag(flagKey);
-    const configDetails = this.getConfigDetails();
+  private newFlagEvaluationDetailsBuilder(
+    config: IConfiguration,
+    flagKey: string,
+  ): FlagEvaluationDetailsBuilder {
+    const flag = this.getNormalizedFlag(config, flagKey);
+    const configDetails = config.getFlagConfigDetails();
     return new FlagEvaluationDetailsBuilder(
       configDetails.configEnvironment.name,
       flag?.allocations ?? [],
@@ -1125,35 +1147,17 @@ export default class EppoClient {
     );
   }
 
-  private getConfigDetails(): ConfigDetails {
-    return {
-      configFetchedAt: this.flagConfigurationStore.getConfigFetchedAt() ?? '',
-      configPublishedAt: this.flagConfigurationStore.getConfigPublishedAt() ?? '',
-      configEnvironment: this.flagConfigurationStore.getEnvironment() ?? {
-        name: '',
-      },
-      configFormat: this.flagConfigurationStore.getFormat() ?? '',
-    };
-  }
-
-  private getFlag(flagKey: string): Flag | null {
-    return this.isObfuscated()
-      ? this.getObfuscatedFlag(flagKey)
-      : this.flagConfigurationStore.get(flagKey);
+  private getNormalizedFlag(config: IConfiguration, flagKey: string): Flag | null {
+    return this.isObfuscated(config)
+      ? this.getObfuscatedFlag(config, flagKey)
+      : config.getFlag(flagKey);
   }
 
-  private getObfuscatedFlag(flagKey: string): Flag | null {
-    const flag: ObfuscatedFlag | null = this.flagConfigurationStore.get(
-      getMD5Hash(flagKey),
-    ) as ObfuscatedFlag;
+  private getObfuscatedFlag(config: IConfiguration, flagKey: string): Flag | null {
+    const flag: ObfuscatedFlag | null = config.getFlag(getMD5Hash(flagKey)) as ObfuscatedFlag;
     return flag ? decodeFlag(flag) : null;
   }
 
-  private getBandit(banditKey: string): BanditParameters | null {
-    // Upstreams for this SDK do not yet support obfuscating bandits, so no `isObfuscated` check here.
-    return this.banditModelConfigurationStore?.get(banditKey) ?? null;
-  }
-
   // noinspection JSUnusedGlobalSymbols
   getFlagKeys() {
     /**
@@ -1162,16 +1166,11 @@ export default class EppoClient {
      *
      * Note that it is generally not a good idea to preload all flag configurations.
      */
-    return this.flagConfigurationStore.getKeys();
+    return this.getConfiguration().getFlagKeys();
   }
 
   isInitialized() {
-    return (
-      this.flagConfigurationStore.isInitialized() &&
-      (!this.banditVariationConfigurationStore ||
-        this.banditVariationConfigurationStore.isInitialized()) &&
-      (!this.banditModelConfigurationStore || this.banditModelConfigurationStore.isInitialized())
-    );
+    return this.getConfiguration().isInitialized();
   }
 
   /** @deprecated Use `setAssignmentLogger` */
@@ -1237,7 +1236,7 @@ export default class EppoClient {
   }
 
   getFlagConfigurations(): Record<string, Flag> {
-    return this.flagConfigurationStore.entries();
+    return this.getConfiguration().getFlags();
   }
 
   private flushQueuedEvents<T>(eventQueue: BoundedEventQueue<T>, logFunction?: (event: T) => void) {
@@ -1305,13 +1304,14 @@ export default class EppoClient {
 
   private buildLoggerMetadata(): Record<string, unknown> {
     return {
-      obfuscated: this.isObfuscated(),
+      obfuscated: this.isObfuscated(this.getConfiguration()),
       sdkLanguage: 'javascript',
       sdkLibVersion: LIB_VERSION,
     };
   }
 
   private computeBanditsForFlags(
+    config: IConfiguration,
     subjectKey: string,
     subjectAttributes: ContextAttributes,
     banditActions: Record<FlagKey, BanditActions>,
@@ -1325,6 +1325,7 @@ export default class EppoClient {
       if (flagVariation) {
         // Precompute a bandit, if there is one matching this variation.
         const precomputedResult = this.getPrecomputedBandit(
+          config,
           flagKey,
           flagVariation.variationValue,
           subjectKey,
@@ -1339,27 +1340,15 @@ export default class EppoClient {
     return banditResults;
   }
 
-  private findBanditByVariation(flagKey: string, variationValue: string): BanditParameters | null {
-    const banditVariations = this.banditVariationConfigurationStore?.get(flagKey);
-    const banditKey = banditVariations?.find(
-      (banditVariation) => banditVariation.variationValue === variationValue,
-    )?.key;
-
-    if (banditKey) {
-      // Retrieve the model parameters for the bandit
-      return this.getBandit(banditKey);
-    }
-    return null;
-  }
-
   private getPrecomputedBandit(
+    config: IConfiguration,
     flagKey: string,
     variationValue: string,
     subjectKey: string,
     subjectAttributes: ContextAttributes,
     banditActions: BanditActions,
   ): IPrecomputedBandit | null {
-    const bandit = this.findBanditByVariation(flagKey, variationValue);
+    const bandit = config.getFlagVariationBandit(flagKey, variationValue);
     if (!bandit) {
       return null;
     }