simple cache with automatic expiration/ cherry pick from commit ca1d921f

backend/src/helpers/simpleObjectCache.ts

@@ -0,0 +1,64 @@
+import { Logger } from "pino";
+
+/**
+ * A simple object cache with a time-to-live (TTL) for each key
+ */
+export class SimpleObjectCache {
+  private ttl: number;
+
+  private logger: Logger;
+
+  private cache: Map<string, { value: any; timer: NodeJS.Timeout }>;
+
+  /**
+   * @param ttl Time to live in milliseconds
+   * @param logger
+   */
+  constructor(ttl: number, logger: Logger = null) {
+    this.ttl = ttl;
+    this.logger = logger;
+    this.cache = new Map();
+  }
+
+  /**
+   * Set a key-value pair in the cache
+   * @param key
+   * @param value
+   * @returns void
+   * @example cache.set('foo', 'bar');
+   * @example cache.set('foo', { bar: 'baz' });
+   */
+  set(key: string, value: any) {
+    // If a timer already exists for this key, clear it
+    if (this.cache.has(key)) {
+      clearTimeout(this.cache.get(key)!.timer);
+      this.logger?.debug(`Cache key ${key} was cleared`);
+    }
+
+    // Set a new timer
+    const timer = setTimeout(() => {
+      this.cache.delete(key);
+      this.logger?.debug(`Cache key ${key} was expired`);
+    }, this.ttl);
+
+    // Store the value and the timer in the cache
+    this.cache.set(key, { value, timer });
+    this.logger?.debug(`Cache key ${key} was saved`);
+  }
+
+  /**
+   * Get a value from the cache
+   * @param key
+   * @returns The value stored in the cache
+   * @example cache.get('foo');
+   */
+  get(key: string) {
+    const data = this.cache.get(key);
+    if (!data) {
+      return null;
+    }
+
+    this.logger?.debug(`Cache key ${key} was accessed`);
+    return data.value;
+  }
+}