Cache Product Pages in Redis: Code Review Practice

Product pages are our most requested route, and every view runs a database read plus a pricing call. This caches the rendered page in Redis for 5 minutes and invalidates it when a product is updated. On staging the p95 for product pages dropped from 180 ms to 12 ms.

Asrc/catalog/productCache.ts1 of 3

Files Changed

src/catalog/

src/catalog/productCache.ts

TypeScript · Click a line number to comment · Tap a line to comment

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import type { Redis } from "ioredis";

import type { ProductPage } from "./types";

const TTL_SECONDS = 300;

/** Cache-aside store for rendered product pages. */

export class ProductCache {

constructor(private readonly redis: Redis) {}

private key(productId: string): string {

return `product-page:${productId}`;

}

async getOrLoad(

productId: string,

load: () => Promise<ProductPage | null>,

): Promise<ProductPage | null> {

const cached = await this.redis.get(this.key(productId));

if (cached !== null) return JSON.parse(cached) as ProductPage | null;

const page = await load();

await this.redis.set(this.key(productId), JSON.stringify(page), "EX", TTL_SECONDS);

return page;

}

async invalidate(productId: string): Promise<void> {

await this.redis.del(this.key(productId));

}

src/catalog/productCache.ts

src/catalog/productService.ts

src/catalog/productCache.test.ts