Enterprise Redis Caching: Invalidation Strategies, Stampede Prevention & Distributed Locks

import Redis from 'ioredis';

const redis = new Redis(process.env.REDIS_URL!);

export async function getOrSetCache<T>(
  key: string,
  fetchFn: () => Promise<T>,
  baseTtlSeconds: number = 3600
): Promise<T> {
  const cached = await redis.get(key);
  if (cached) {
    return JSON.parse(cached) as T;
  }

  // Add random jitter to prevent synchronized cache stampedes
  const jitter = Math.floor(Math.random() * (baseTtlSeconds * 0.15));
  const ttl = baseTtlSeconds + jitter;

  // Fetch and cache
  const freshData = await fetchFn();
  await redis.set(key, JSON.stringify(freshData), 'EX', ttl);
  return freshData;
}