feat(backend): caching middleware

packages/backend/src/middleware/cache.ts

@@ -0,0 +1,37 @@
+import { styleText } from "node:util";
+import type { NextFunction, Request, RequestHandler, Response } from "express";
+import Cache from "@/app/Cache";
+
+export const middlewareCache = new Cache();
+
+function log(hit: "hit" | "miss", cacheKey: string) {
+  console.debug(
+    "Cache",
+    styleText(["bold", "green"], hit.toUpperCase()),
+    "for",
+    styleText(["italic"], cacheKey),
+  );
+}
+
+export default function cacheGets(staleTimeMs?: number): RequestHandler {
+  return (req: Request, res: Response, next: NextFunction) => {
+    if (req.method.toUpperCase() !== "GET") next();
+
+    const key = req.originalUrl || req.url;
+
+    if (middlewareCache.has(key)) {
+      log("hit", key);
+      return res.json(middlewareCache.get(key));
+    }
+
+    log("miss", key);
+
+    const originalJson = res.json.bind(res);
+    res.json = (data) => {
+      middlewareCache.set(key, data, staleTimeMs);
+      return originalJson(data);
+    };
+
+    next();
+  };
+}

packages/backend/src/routes/api/v1/history.ts

@@ -1,5 +1,6 @@
 import type { Point } from "@blurple-canvas-web/types";
 import { Router } from "express";
+import cacheGets from "@/middleware/cache";
 import {
   assertLoggedIn,
   requireCanvasModerator,
@@ -23,6 +24,7 @@ export const historyRouter = typedRouter(Router({ mergeParams: true }));
 historyRouter.get(
   "/",
   validate({ params: CanvasIdParamModel, query: PixelHistoryParamModel }),
+  cacheGets(),
   async (req, res) => {
     const startedAt = performance.now();
     const pixelHistory = await getPixelHistorySummary(

packages/backend/src/routes/api/v1/index.ts

@@ -1,4 +1,5 @@
 import { Router } from "express";
+import cacheGets from "@/middleware/cache";
 import { blocklistRouter } from "./blocklist";
 import { canvasRouter } from "./canvas";
 import { discordRouter } from "./discord";
@@ -14,7 +15,7 @@ apiV1Router.use("/blocklist", blocklistRouter);
 apiV1Router.use("/canvas", canvasRouter);
 apiV1Router.use("/discord", discordRouter);
 apiV1Router.use("/event", eventRouter);
-apiV1Router.use("/frame", frameRouter);
-apiV1Router.use("/notice", noticeRouter);
-apiV1Router.use("/palette", paletteRouter);
-apiV1Router.use("/statistics", statisticsRouter);
+apiV1Router.use("/frame", frameRouter, cacheGets(300_000));
+apiV1Router.use("/notice", noticeRouter, cacheGets(300_000));
+apiV1Router.use("/palette", paletteRouter, cacheGets(600_000));
+apiV1Router.use("/statistics", statisticsRouter, cacheGets(300_000));