feat(utils): cache with ttl

Author: martykan

packages/utils/src/cache.ts

@@ -0,0 +1,30 @@
+/**
+ * Cache class which allows to store Key-Value pairs with a TTL for each key
+ */
+export class Cache {
+    store: Map<string, { value: any; ttl: number }>;
+
+    constructor() {
+        this.store = new Map();
+    }
+
+    set(key: string, value: any, ttl: number) {
+        this.store.set(key, { value, ttl: Date.now() + ttl });
+    }
+
+    get(key: string) {
+        const entry = this.store.get(key);
+        if (!entry) return;
+        if (entry.ttl < Date.now()) {
+            this.store.delete(key);
+
+            return;
+        }
+
+        return entry.value;
+    }
+
+    delete(key: string) {
+        this.store.delete(key);
+    }
+}

packages/utils/src/index.ts

@@ -8,6 +8,7 @@ export * from './arrayPartition';
 export * from './arrayShuffle';
 export * from './arrayToDictionary';
 export * from './bytesToHumanReadable';
+export * from './cache';
 export * from './capitalizeFirstLetter';
 export * from './cloneObject';
 export * from './countBytesInString';

packages/utils/tests/cache.test.ts

@@ -0,0 +1,31 @@
+import { Cache } from '../src/cache';
+
+const delay = (ms: number) => jest.advanceTimersByTime(ms);
+
+const TTL = 100;
+
+describe('Cache', () => {
+    let cache: Cache;
+
+    beforeEach(() => {
+        jest.useFakeTimers();
+        cache = new Cache();
+    });
+
+    it('set and get', () => {
+        cache.set('key', 'value', TTL);
+        expect(cache.get('key')).toEqual('value');
+    });
+
+    it('get with expired TTL', () => {
+        cache.set('key', 'value', TTL);
+        delay(TTL + 1);
+        expect(cache.get('key')).toBeUndefined();
+    });
+
+    it('delete', () => {
+        cache.set('key', 'value', TTL);
+        cache.delete('key');
+        expect(cache.get('key')).toBeUndefined();
+    });
+});