Add Memorelay storages module

src/storages/memorelay.ts

@@ -0,0 +1,63 @@
+import { Debug, type Event, type Filter, LRUCache } from '@/deps.ts';
+import { getFilterId, getMicroFilters, isMicrofilter } from '@/filter.ts';
+import { type EventStore, type GetEventsOpts } from '@/store.ts';
+
+/** In-memory data store for events using microfilters. */
+class Memorelay implements EventStore {
+  #debug = Debug('ditto:memorelay');
+  #events: LRUCache<string, Event>;
+
+  constructor(...args: ConstructorParameters<typeof LRUCache<string, Event>>) {
+    this.#events = new LRUCache<string, Event>(...args);
+  }
+
+  /** Get events from memory. */
+  getEvents<K extends number>(filters: Filter<K>[], opts: GetEventsOpts = {}): Promise<Event<K>[]> {
+    if (opts.signal?.aborted) return Promise.resolve([]);
+    if (!filters.length) return Promise.resolve([]);
+    this.#debug('REQ', JSON.stringify(filters));
+
+    const results: Event<K>[] = [];
+
+    for (const filter of filters) {
+      if (isMicrofilter(filter)) {
+        const event = this.#events.get(getFilterId(filter));
+        if (event) {
+          results.push(event as Event<K>);
+        }
+      }
+    }
+
+    return Promise.resolve(results);
+  }
+
+  /** Insert an event into memory. */
+  storeEvent(event: Event): Promise<void> {
+    for (const microfilter of getMicroFilters(event)) {
+      const filterId = getFilterId(microfilter);
+      const existing = this.#events.get(filterId);
+      if (!existing || event.created_at > existing.created_at) {
+        this.#events.set(filterId, event);
+      }
+    }
+    return Promise.resolve();
+  }
+
+  /** Count events in memory for the filters. */
+  async countEvents(filters: Filter[]): Promise<number> {
+    const events = await this.getEvents(filters);
+    return events.length;
+  }
+
+  /** Delete events from memory. */
+  deleteEvents(filters: Filter[]): Promise<void> {
+    for (const filter of filters) {
+      if (isMicrofilter(filter)) {
+        this.#events.delete(getFilterId(filter));
+      }
+    }
+    return Promise.resolve();
+  }
+}
+
+export { Memorelay };