Reorganize project. Add folder for shared code between backend/dashboard. Switch from jest to ava for tests.

backend/src/SimpleCache.ts

@@ -0,0 +1,69 @@
+import Timeout = NodeJS.Timeout;
+
+const CLEAN_INTERVAL = 1000;
+
+export class SimpleCache<T = any> {
+  protected readonly retentionTime: number;
+  protected readonly maxItems: number;
+
+  protected cleanTimeout: Timeout;
+  protected unloaded: boolean;
+
+  protected store: Map<string, { remove_at: number; value: T }>;
+
+  constructor(retentionTime: number, maxItems?: number) {
+    this.retentionTime = retentionTime;
+    this.maxItems = maxItems;
+
+    this.store = new Map();
+  }
+
+  unload() {
+    this.unloaded = true;
+    clearTimeout(this.cleanTimeout);
+  }
+
+  cleanLoop() {
+    const now = Date.now();
+    for (const [key, info] of this.store.entries()) {
+      if (now >= info.remove_at) {
+        this.store.delete(key);
+      }
+    }
+
+    if (!this.unloaded) {
+      this.cleanTimeout = setTimeout(() => this.cleanLoop(), CLEAN_INTERVAL);
+    }
+  }
+
+  set(key: string, value: T) {
+    this.store.set(key, {
+      remove_at: Date.now() + this.retentionTime,
+      value,
+    });
+
+    if (this.maxItems && this.store.size > this.maxItems) {
+      const keyToDelete = this.store.keys().next().value;
+      this.store.delete(keyToDelete);
+    }
+  }
+
+  get(key: string): T {
+    const info = this.store.get(key);
+    if (!info) return null;
+
+    return info.value;
+  }
+
+  has(key: string) {
+    return this.store.has(key);
+  }
+
+  delete(key: string) {
+    this.store.delete(key);
+  }
+
+  clear() {
+    this.store.clear();
+  }
+}