cache-strategy-invalidation-expert

license	Apache-2.0
name	cache-strategy-invalidation-expert
description	Redis caching patterns, cache-aside, write-through, TTL strategies, and invalidation. Activate on: caching, Redis, cache invalidation, cache-aside, write-through, TTL, CDN cache, stale-while-revalidate. NOT for: CDN/reverse proxy setup (use api-gateway-reverse-proxy-expert), database query optimization (use data-warehouse-optimizer).
allowed-tools	Read,Write,Edit,Bash(npm:*,npx:*,redis-cli:*)
category	Backend & Infrastructure
tags	["caching","redis","invalidation","performance","ttl"]
pairs-with	[{"skill":"api-rate-limiting-throttling-expert","reason":"Redis powers both caching and rate limiting"},{"skill":"websocket-realtime-expert","reason":"Cache invalidation can trigger real-time updates"},{"skill":"multi-tenant-architecture-expert","reason":"Cache keys must be tenant-scoped in multi-tenant systems"}]

Cache Strategy & Invalidation Expert

Design and implement caching architectures using Redis, application-level caching, and CDN layers with reliable invalidation strategies.

Activation Triggers

Activate on: "caching", "Redis cache", "cache invalidation", "cache-aside", "write-through", "TTL", "stale-while-revalidate", "cache stampede", "cache warming"

NOT for: CDN/proxy configuration → api-gateway-reverse-proxy-expert | Database query tuning → data-warehouse-optimizer | Connection pooling → database-connection-pool-manager

Quick Start

1. Identify cache candidates — read-heavy, expensive to compute, tolerant of staleness
2. Choose pattern — cache-aside (most common), write-through (consistency), write-behind (performance)
3. Set TTL strategy — short TTL for volatile data (60s), long TTL + event invalidation for stable data
4. Prevent stampede — use probabilistic early refresh or mutex lock on cache miss
5. Monitor hit rate — target >90% hit rate; below 70% means your cache strategy is wrong

Core Capabilities

Domain	Technologies
In-Memory	Redis 7.4+, Valkey, DragonflyDB, KeyDB
Application	Node LRU cache, Cacheable, unstorage
HTTP/CDN	Cache-Control, stale-while-revalidate, Surrogate-Key
Multi-Layer	L1 (in-process) → L2 (Redis) → L3 (CDN)
Invalidation	Event-driven purge, TTL, tag-based (Surrogate-Key)

Architecture Patterns

Cache-Aside with Stampede Prevention

import { Redis } from 'ioredis';

const redis = new Redis();
const LOCK_TTL = 5; // seconds

  cacheAside<T>(
  : ,
  : ,
  :  <T>
): <T> {
  
   cached =  redis.(key);
   (cached)  .(cached);

  
   lockKey = ;
   acquired =  redis.(lockKey, , , , );

   (!acquired) {
    
      ( (r, ));
     (key, ttl, fetcher);
  }

   {
     data =  ();
     redis.(key, .(data), , ttl);
     data;
  }  {
     redis.(lockKey);
  }
}