feat(gofeatureflag): added cache option (#1284)

Signed-off-by: Simas Usas <simas.usas@vinted.com>

Author: simas-usas

libs/providers/go-feature-flag/src/lib/controller/cache.ts

@@ -1,4 +1,4 @@
-import { GoFeatureFlagProviderOptions } from '../model';
+import { GoFeatureFlagProviderOptions, Cache } from '../model';
 import { EvaluationContext, Logger, ResolutionDetails } from '@openfeature/server-sdk';
 import { LRUCache } from 'lru-cache';
 import hash from 'object-hash';
@@ -10,7 +10,7 @@ export class CacheController {
   // logger is the Open Feature logger to use
   private logger?: Logger;
   // cache contains the local cache used in the provider to avoid calling the relay-proxy for every evaluation
-  private readonly cache?: LRUCache<string, ResolutionDetails<any>>;
+  private readonly cache?: Cache;
   // options for this provider
   private readonly options: GoFeatureFlagProviderOptions;
 
@@ -20,7 +20,7 @@ export class CacheController {
     this.logger = logger;
     const cacheSize =
       options.flagCacheSize !== undefined && options.flagCacheSize !== 0 ? options.flagCacheSize : 10000;
-    this.cache = new LRUCache({ maxSize: cacheSize, sizeCalculation: () => 1 });
+    this.cache = options.cache || new LRUCache({ maxSize: cacheSize, sizeCalculation: () => 1 });
   }
 
   get(flagKey: string, evaluationContext: EvaluationContext): ResolutionDetails<any> | undefined {

libs/providers/go-feature-flag/src/lib/model.ts

@@ -1,4 +1,4 @@
-import { ErrorCode, EvaluationContextValue } from '@openfeature/server-sdk';
+import { ErrorCode, EvaluationContextValue, ResolutionDetails } from '@openfeature/server-sdk';
 
 export interface GOFFEvaluationContext {
   key: string;
@@ -33,6 +33,15 @@ export interface GoFeatureFlagProxyResponse<T> {
   cacheable: boolean;
 }
 
+/**
+ * Cache is the interface used to implement an alternative cache for the provider.
+ */
+export interface Cache {
+  get: (key: string) => ResolutionDetails<any> | undefined;
+  set: (key: string, value: ResolutionDetails<any>, options?: Record<string, any>) => void;
+  clear: () => void;
+}
+
 /**
  * GoFeatureFlagProviderOptions is the object containing all the provider options
  * when initializing the open-feature provider.
@@ -47,6 +56,9 @@ export interface GoFeatureFlagProviderOptions {
   // Default: null
   apiKey?: string;
 
+  // cache (optional) set an alternative cache library.
+  cache?: Cache;
+
   // disableCache (optional) set to true if you would like that every flag evaluation goes to the GO Feature Flag directly.
   disableCache?: boolean;