// Cache Aside Pattern Implementation
public class CacheAsideService {
    
    public User getUser(String userId) {
        // Step 1: Check cache
        User user = redis.get("user:" + userId);
        if (user != null) {
            return user;  // Cache HIT - fast path
        }
        
        // Step 2: Cache MISS - load from database
        user = database.findUser(userId);
        
        // Step 3: Store in cache for future requests
        redis.set("user:" + userId, user, Duration.ofMinutes(30));
        
        return user;
    }
}

// Solution 1: Locking (Only one request fetches)
public User getUserWithLock(String userId) {
    String cacheKey = "user:" + userId;
    User user = redis.get(cacheKey);
    if (user != null) return user;
    
    // Acquire distributed lock
    if (redis.setnx("lock:" + cacheKey, "1", Duration.ofSeconds(5))) {
        try {
            // Only one thread gets here
            user = database.findUser(userId);
            redis.set(cacheKey, user, Duration.ofMinutes(30));
        } finally {
            redis.del("lock:" + cacheKey);
        }
    } else {
        // Wait for first thread to populate cache
        Thread.sleep(100);
        user = redis.get(cacheKey);
    }
    return user;
}

// Solution 2: Random TTL Jitter
Duration ttl = Duration.ofMinutes(30).plus(Duration.ofMillis(random.nextInt(5000)));
redis.set(cacheKey, data, ttl);  // 30 minutes ± 5 seconds