Improve the NIP-05 cache

src/utils/SimpleLRU.ts

@@ -0,0 +1,37 @@
+// deno-lint-ignore-file ban-types
+
+import { LRUCache, type MapCache } from '@/deps.ts';
+
+type FetchFn<K extends {}, V extends {}, O extends {}> = (key: K, opts: O) => Promise<V>;
+
+interface FetchFnOpts {
+  signal?: AbortSignal | null;
+}
+
+export class SimpleLRU<
+  K extends {},
+  V extends {},
+  O extends {} = FetchFnOpts,
+> implements MapCache<K, V, O> {
+  protected cache: LRUCache<K, V, void>;
+
+  constructor(fetchFn: FetchFn<K, V, { signal: AbortSignal }>, opts: LRUCache.Options<K, V, void>) {
+    this.cache = new LRUCache({
+      fetchMethod: (key, _staleValue, { signal }) => fetchFn(key, { signal: signal as AbortSignal }),
+      ...opts,
+    });
+  }
+
+  async fetch(key: K, opts?: O): Promise<V> {
+    const result = await this.cache.fetch(key, opts);
+    if (result === undefined) {
+      throw new Error('SimpleLRU: fetch failed');
+    }
+    return result;
+  }
+
+  put(key: K, value: V): Promise<void> {
+    this.cache.set(key, value);
+    return Promise.resolve();
+  }
+}