Cache strategy

Cache Strategy Implementation

I'll analyze your application and implement appropriate caching strategies to improve performance and reduce server load.

Arguments: $ARGUMENTS - cache type focus (e.g., "http", "service-worker", "redis", "browser")

Strategic Planning Process

<think> Effective caching requires careful strategy:

1. Application Analysis

   • What type of application? (SPA, MPA, API, static site)
   • What data changes frequently vs. rarely?
   • What's cached currently, if anything?
   • Client-side, server-side, or both?
   • CDN usage and configuration

2. Cache Layer Selection

   • Browser cache (HTTP headers)
   • Service worker cache (offline-first PWA)
   • Application cache (in-memory, localStorage)
   • Server cache (Redis, Memcached)
   • CDN cache (edge caching)
   • Database query cache

3. Cache Invalidation Strategy

   • Time-based expiration (TTL)
   • Event-based invalidation
   • Version-based cache busting
   • Manual invalidation mechanisms
   • Stale-while-revalidate patterns

4. Performance vs. Freshness Tradeoff

   • Critical real-time data (no cache or very short TTL)
   • Semi-dynamic data (short TTL, stale-while-revalidate)
   • Static assets (long TTL, immutable)
   • User-specific data (private cache) </think>

Phase 1: Cache Audit

MANDATORY FIRST STEPS:

1. Detect application type and architecture
2. Analyze current caching configuration
3. Identify cacheable resources
4. Determine cache invalidation needs

Let me analyze your current caching setup:

# Check for existing cache configurations
echo "=== Cache Configuration Audit ==="

# Check for service worker
if [ -f "public/service-worker.js" ] || [ -f "src/service-worker.js" ] || [ -f "sw.js" ]; then
    echo "✓ Service Worker detected"
    ls -lh **/service-worker.js **/sw.js 2>/dev/null | head -5
else
    echo "✗ No Service Worker found"
fi

# Check for HTTP caching headers (common web server configs)
if [ -f ".htaccess" ]; then
    echo "✓ Apache .htaccess found"
    grep -i "cache-control\|expires" .htaccess 2>/dev/null | head -5
fi

if [ -f "nginx.conf" ] || [ -f "nginx/*.conf" ]; then
    echo "✓ Nginx config found"
    grep -i "cache\|expires" nginx*.conf 2>/dev/null | head -5
fi

# Check for Redis/Memcached dependencies
if grep -q "\"redis\"" package.json 2>/dev/null; then
    echo "✓ Redis client installed"
fi

if grep -q "\"memcached\"" package.json 2>/dev/null; then
    echo "✓ Memcached client installed"
fi

# Check for caching libraries
if grep -q "\"workbox\"" package.json 2>/dev/null; then
    echo "✓ Workbox (service worker toolkit) installed"
fi

# Check CDN configuration
if [ -f "vercel.json" ] || [ -f "netlify.toml" ]; then
    echo "✓ CDN configuration detected"
fi

Phase 2: Cache Strategy Design

Based on application type, I'll design appropriate caching layers:

Browser Cache Strategy (HTTP Headers)

Static Assets:

• Long cache duration (1 year)
• Immutable for versioned assets
• Public caching allowed
• Proper ETag configuration

Dynamic Content:

• Short cache duration or no-cache
• Private cache for user-specific data
• Stale-while-revalidate for better UX
• Proper cache-control directives

API Responses:

• Cache-Control based on data freshness
• ETag for conditional requests
• Vary headers for content negotiation
• Private cache for authenticated requests

Service Worker Cache Strategy

Cache-First (Offline-First):

• Static assets, fonts, images
• Application shell
• Third-party libraries

Network-First:

• API calls
• Dynamic content
• Real-time data

Stale-While-Revalidate:

• Semi-dynamic content
• News feeds, product listings
• Balance freshness with performance

Cache-Only:

• Fallback offline pages
• Critical UI assets

Application-Level Caching

In-Memory Caching:

• Computed values (memoization)
• Expensive calculations
• API response caching
• Query result caching

Local Storage:

• User preferences
• Authentication tokens
• Offline data sync
• Application state persistence

Server-Side Caching

Redis/Memcached:

• Database query results
• Computed data
• Session storage
• API response caching
• Rate limiting data

CDN Edge Caching:

• Static assets
• API responses (when appropriate)
• Geographic distribution
• DDoS protection

Phase 3: Implementation

I'll implement selected caching strategies:

HTTP Caching Headers

For Node.js/Express:

// Static assets with long-term caching
app.use('/static', express.static('public', {
  maxAge: '1y',
  immutable: true,
  etag: true
}));

// API responses with short-term caching
app.use('/api', (req, res, next) => {
  res.set('Cache-Control', 'private, max-age=300'); // 5 minutes
  next();
});

For Next.js:

// next.config.js
module.exports = {
  async headers() {
    return [
      {
        source: '/_next/static/:path*',
        headers: [
          {
            key: 'Cache-Control',
            value: 'public, max-age=31536000, immutable',
          },
        ],
      },
    ];
  },
};

For Nginx:

# Static assets
location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff|woff2)$ {
    expires 1y;
    add_header Cache-Control "public, immutable";
}

# HTML files - no cache
location ~* \.html$ {
    expires -1;
    add_header Cache-Control "no-cache, no-store, must-revalidate";
}

Service Worker Implementation

Workbox Configuration:

import { precacheAndRoute } from 'workbox-precaching';
import { registerRoute } from 'workbox-routing';
import { CacheFirst, NetworkFirst, StaleWhileRevalidate } from 'workbox-strategies';
import { ExpirationPlugin } from 'workbox-expiration';
import { CacheableResponsePlugin } from 'workbox-cacheable-response';

// Precache static assets
precacheAndRoute(self.__WB_MANIFEST);

// Cache images with Cache First strategy
registerRoute(
  ({ request }) => request.destination === 'image',
  new CacheFirst({
    cacheName: 'images',
    plugins: [
      new ExpirationPlugin({
        maxEntries: 60,
        maxAgeSeconds: 30 * 24 * 60 * 60, // 30 Days
      }),
    ],
  })
);

// API calls with Network First strategy
registerRoute(
  ({ url }) => url.pathname.startsWith('/api/'),
  new NetworkFirst({
    cacheName: 'api-cache',
    plugins: [
      new CacheableResponsePlugin({
        statuses: [0, 200],
      }),
      new ExpirationPlugin({
        maxAgeSeconds: 5 * 60, // 5 minutes
      }),
    ],
  })
);

// CSS and JS with Stale While Revalidate
registerRoute(
  ({ request }) => request.destination === 'style' || request.destination === 'script',
  new StaleWhileRevalidate({
    cacheName: 'static-resources',
  })
);

Memoization Patterns

React Memoization:

import { useMemo, useCallback } from 'react';
import { memo } from 'react';

// Memoize expensive calculations
const ExpensiveComponent = ({ data }) => {
  const processedData = useMemo(() => {
    return expensiveCalculation(data);
  }, [data]);

  const handleClick = useCallback(() => {
    // Handler logic
  }, []);

  return <div>{processedData}</div>;
};

export default memo(ExpensiveComponent);

Function Memoization:

// Simple memoization utility
function memoize(fn) {
  const cache = new Map();
  return (...args) => {
    const key = JSON.stringify(args);
    if (cache.has(key)) {
      return cache.get(key);
    }
    const result = fn(...args);
    cache.set(key, result);
    return result;
  };
}

// LRU cache with size limit
class LRUCache {
  constructor(limit = 100) {
    this.cache = new Map();
    this.limit = limit;
  }

  get(key) {
    if (!this.cache.has(key)) return undefined;
    const value = this.cache.get(key);
    this.cache.delete(key);
    this.cache.set(key, value); // Move to end
    return value;
  }

  set(key, value) {
    if (this.cache.has(key)) {
      this.cache.delete(key);
    } else if (this.cache.size >= this.limit) {
      const firstKey = this.cache.keys().next().value;
      this.cache.delete(firstKey);
    }
    this.cache.set(key, value);
  }
}

Redis Caching

Express with Redis:

const redis = require('redis');
const client = redis.createClient();

// Cache middleware
const cache = (duration) => {
  return async (req, res, next) => {
    const key = `cache:${req.originalUrl}`;

    try {
      const cached = await client.get(key);
      if (cached) {
        return res.json(JSON.parse(cached));
      }

      // Store original send function
      const originalSend = res.json.bind(res);

      // Override send to cache response
      res.json = (body) => {
        client.setex(key, duration, JSON.stringify(body));
        return originalSend(body);
      };

      next();
    } catch (err) {
      next();
    }
  };
};

// Use cache middleware
app.get('/api/data', cache(300), async (req, res) => {
  const data = await fetchData();
  res.json(data);
});

Phase 4: Cache Invalidation

I'll implement appropriate invalidation strategies:

Time-Based Expiration:

• Set appropriate TTL values
• Use max-age headers
• Configure Redis expiration
• Implement cleanup routines

Event-Based Invalidation:

• Clear cache on data updates
• Invalidate related cache entries
• Use cache tags for grouped invalidation
• Implement webhook-based clearing

Version-Based Cache Busting:

• Content hashing for static assets
• API versioning
• Service worker updates
• Cache key versioning

Token Optimization

Expected range: 1,000–1,800 tokens (initial), 300 tokens (cache hit)

Caching: Caches detected cache patterns in .claude/cache/cache-strategy/cache_patterns.json for 7 days.

Early exit: Returns immediately if caching patterns are already optimal for the project.

Patterns used: Grep-before-Read, early exit, template-based generation, caching