cache-strategy-planner

Purpose

Architect robust, multi-layer caching strategies (HTTP/CDN edge, distributed Redis/Memcached, in-process local memory) with explicit TTLs, cache invalidation hooks, and cache stampede (thundering herd) protections.

When to Use

• High-read database bottlenecks or slow third-party API response times.
• Designing CDN caching rules (Cache-Control, stale-while-revalidate, surrogate keys).
• Fixing cache stampedes that crash origin servers when popular cache keys expire.

What to Analyze

1. Cache Tier Selection: L1 (In-memory LRU, sub-millisecond) vs L2 (Redis Cluster, 1-2ms) vs Edge CDN (Cloudflare/Fastly).
2. Write Strategy: Cache-Aside (Lazy Loading), Write-Through, Write-Behind (Write-Back).
3. Invalidation Policy: Time-To-Live (TTL) with jitter vs Event-driven explicit key purge vs Tag-based invalidation.
4. Stampede & Thundering Herd Defense: Mutex locking (singleflight pattern) or probabilistic early expiration (XFetch algorithm).
5. Serialization & Memory Footprint: Protobuf, MessagePack, or compressed JSON over raw strings.

Output Format

• Caching Architecture Diagram: Data flow between Client, CDN, Redis, and Database.
• Cache Policy Table: [Data Type | Storage Tier | TTL | Invalidation Trigger | Stampede Defense].
• Singleflight / Cache Wrapper Code: Production-ready caching utility with fallback.

Avoid

• Caching mutable data without a clear invalidation strategy.
• Omitting TTL jitter (all cache keys expiring at the exact same second).