adds : method to fetch events betwen timestamps. fixes #4

Author: Kushagra Singh Bisen

src/service/CacheService.test.ts

@@ -29,8 +29,8 @@ describe('CacheService', () => {
         expect(is_disconnected).toBe(true);
     });
 
-    it('should_describe_the_cache', async() => {
+    it('should_describe_the_cache', async () => {
         const status = await cacheService.get_status();
         expect(status).toBe('wait');
-    })
+    });
 }); 

src/service/CacheService.ts

@@ -88,5 +88,33 @@ export class CacheService {
     async get_status(): Promise<RedisStatus> {
         return await this.client.status;
     }
+    /**
+     * Get all key-value pairs from the Redis cache.
+     * This method is not recommended for large databases, as it will load all key-value pairs into memory and be slow.
+     * However, it is useful for notification caching, where the database is expected to be small to get the missing notifications.
+     * @return {Promise<{ [key: string]: string }>} - A promise that resolves to an object containing all key-value pairs in the cache.
+     * @memberof CacheService
+     */
+    async read_whole_database(): Promise<{ [key: string]: string }> {
+        let cursor = '0';
+        const key_values: { [key: string]: string } = {};
+        do {
+            const [newCursor, keys] = await this.client.scan(cursor);
+            cursor = newCursor;
+
+            if (keys.length > 0) {
+                const values = await this.client.mget(...keys);
+                keys.forEach((key: any, index: any) => {
+                    const value = values[index];
+                    if (value !== null) {
+                        key_values[key] = value;
+                    } else {
+                        console.warn(`Key '${key}' does not exist.`);
+                    }
+                });
+            }
+        } while (cursor !== '0');
+        return key_values
+    }
 }
 

src/utils/FetchUtil.ts

@@ -0,0 +1,28 @@
+import { Readable } from "stream"
+import { CacheService } from "../service/CacheService";
+const cache_service = new CacheService();
+export async function getMembers(opts?: {
+    from?: Date,
+    until?: Date,
+}): Promise<Readable> {
+    opts = opts ?? {};
+    const from = opts.from ?? new Date(0);
+    const until = opts.until ?? new Date();
+    const from_epoch = from.getTime();
+    const until_epoch = until.getTime();
+    const member_stream = new Readable({
+        objectMode: true,
+        read() {
+
+        }
+    });
+    const database = await cache_service.read_whole_database();
+    for (const key in database) {
+        const value = database[key];
+        const timestamp = parseInt(key);
+        if (timestamp >= from_epoch && timestamp <= until_epoch) {
+            member_stream.push(value);
+        }
+    }
+    return member_stream;
+}