fix(backend): address review feedback on limiter and cache

Author: chinmaydwivedi

backend/src/dal/leaderboards.ts

@@ -94,8 +94,7 @@ export async function get(
   }
 }
 
-const CACHE_TTL_MS = 10 * 60 * 1000;
-const cachedCounts = new Map<string, { count: number; expiresAt: number }>();
+const cachedCounts = new Map<string, number>();
 
 export async function getCount(
   mode: string,
@@ -104,21 +103,16 @@ export async function getCount(
   uid?: string,
 ): Promise<number> {
   const key = `${language}_${mode}_${mode2}`;
-  const cached = cachedCounts.get(key);
-  if (
-    uid === undefined &&
-    cached !== undefined &&
-    cached.expiresAt > Date.now()
-  ) {
-    return cached.count;
+  if (uid === undefined && cachedCounts.has(key)) {
+    return cachedCounts.get(key) as number;
   } else {
     if (uid === undefined) {
       const count = await getCollection({
         language,
         mode,
         mode2,
       }).estimatedDocumentCount();
-      cachedCounts.set(key, { count, expiresAt: Date.now() + CACHE_TTL_MS });
+      cachedCounts.set(key, count);
       return count;
     } else {
       const result = await aggregateWithAcceptedConnections<{

backend/src/middlewares/rate-limit.ts

@@ -1,10 +1,6 @@
 import MonkeyError from "../utils/error";
 import type { Response, NextFunction, Request } from "express";
-import {
-  RateLimiterMemory,
-  RateLimiterRedis,
-  type RateLimiterAbstract,
-} from "rate-limiter-flexible";
+import { RateLimiterMemory } from "rate-limiter-flexible";
 import {
   rateLimit,
   RateLimitRequestHandler,
@@ -25,7 +21,6 @@ import {
   TsRestRequestWithContext,
 } from "../api/types";
 import { AppRoute, AppRouter } from "@ts-rest/core";
-import * as RedisClient from "../init/redis";
 
 export const REQUEST_MULTIPLIER = isDevEnvironment() ? 100 : 1;
 
@@ -154,31 +149,10 @@ export const rootRateLimiter = rateLimit({
 });
 
 // Bad Authentication Rate Limiter
-// Uses Redis when available for consistency across instances, falls back to memory
-function createBadAuthRateLimiter(): RateLimiterAbstract {
-  const opts = {
-    points: 30 * REQUEST_MULTIPLIER,
-    duration: 60 * 60,
-  };
-
-  const redisConnection = RedisClient.getConnection();
-  if (redisConnection !== null) {
-    return new RateLimiterRedis({
-      ...opts,
-      storeClient: redisConnection,
-      keyPrefix: "bad_auth",
-      insuranceLimiter: new RateLimiterMemory(opts),
-    });
-  }
-
-  return new RateLimiterMemory(opts);
-}
-
-let badAuthRateLimiter: RateLimiterAbstract = createBadAuthRateLimiter();
-
-export function reinitBadAuthRateLimiter(): void {
-  badAuthRateLimiter = createBadAuthRateLimiter();
-}
+const badAuthRateLimiter = new RateLimiterMemory({
+  points: 30 * REQUEST_MULTIPLIER,
+  duration: 60 * 60, //one hour seconds
+});
 
 export async function badAuthRateLimiterHandler(
   req: ExpressRequestWithContext,

backend/src/server.ts

@@ -19,7 +19,6 @@ import { createIndicies as leaderboardDbSetup } from "./dal/leaderboards";
 import { createIndicies as blocklistDbSetup } from "./dal/blocklist";
 import { createIndicies as connectionsDbSetup } from "./dal/connections";
 import { getErrorMessage } from "./utils/error";
-import { reinitBadAuthRateLimiter } from "./middlewares/rate-limit";
 
 async function bootServer(port: number): Promise<Server> {
   try {
@@ -47,9 +46,6 @@ async function bootServer(port: number): Promise<Server> {
       Logger.success("Connected to redis");
       const connection = RedisClient.getConnection();
 
-      Logger.info("Upgrading bad auth rate limiter to Redis...");
-      reinitBadAuthRateLimiter();
-
       Logger.info("Initializing queues...");
       queues.forEach((queue) => {
         queue.init(connection ?? undefined);