Use interface instead of separate class

Author: keelerm84

packages/shared/akamai-edgeworker-sdk/src/featureStore/cache-item.ts

@@ -1,8 +1,10 @@
-import { CacheItem } from './cache-item';
+interface CacheItem {
+  value: any,
+  expiration: number,
+}
 
 export default class Cache {
-  cache: CacheItem | undefined;
-  cachedAt: number | undefined;
+  _cache: CacheItem | undefined;
 
   constructor(private readonly _cacheTtlMs: number) {}
 
@@ -13,26 +15,29 @@ export default class Cache {
     }
 
     // If there isn't a cached item, we must return undefined.
-    if (this.cache === undefined) {
+    if (this._cache === undefined) {
       return undefined;
     }
 
     // A cacheTtlMs of 0 is infinite caching, so we can always return the
     // value.
     //
-    // We also want to return it if the cache is still considered fresh.
-    if (this._cacheTtlMs === 0 || this.cache.fresh(this._cacheTtlMs)) {
-      return this.cache.value;
+    // We also want to return the value if it hasn't expired.
+    if (this._cacheTtlMs === 0 || Date.now() < this._cache.expiration) {
+      return this._cache.value;
     }
 
     // If you have gotten this far, the cache is stale. Better to drop it as a
     // way to short-circuit checking the freshness again.
-    this.cache = undefined;
+    this._cache = undefined;
 
     return undefined;
   }
 
   set(value: any): void {
-    this.cache = new CacheItem(value);
+    this._cache = {
+      value: value,
+      expiration: Date.now() + this._cacheTtlMs,
+    }
   }
 }

packages/shared/akamai-edgeworker-sdk/src/featureStore/cache.ts

@@ -96,25 +96,25 @@ export class EdgeFeatureStore implements LDFeatureStore {
   // This method is used to retrieve the environment payload from the edge
   // provider. It will cache the payload for the duration of the cacheTtlMs.
   private async _getStorePayload(): Promise<ReturnType<typeof deserializePoll>> {
-    let item = this._cache.get();
-    if (item !== undefined) {
-      return item;
+    let payload = this._cache.get();
+    if (payload !== undefined) {
+      return payload;
     }
 
-    const i = await this._edgeProvider.get(this._rootKey);
+    const providerData = await this._edgeProvider.get(this._rootKey);
 
-    if (!i) {
+    if (!providerData) {
       throw new Error(`${this._rootKey} is not found in KV.`);
     }
 
-    item = deserializePoll(i);
-    if (!item) {
+    payload = deserializePoll(providerData);
+    if (!payload) {
       throw new Error(`Error deserializing ${this._rootKey}`);
     }
 
-    this._cache.set(item);
+    this._cache.set(payload);
 
-    return item;
+    return payload;
   }
 
   async initialized(callback: (isInitialized: boolean) => void = noop): Promise<void> {