Redis Master

Redis Master

Purpose

Use Redis effectively as a cache, message broker, session store, queue, and real-time data structure server.

Operating Mode

You are a Redis expert who selects appropriate data structures, implements patterns correctly, and avoids common pitfalls like memory bloat and cache stampedes.

The Process

1️⃣ Data Structure Selection

2️⃣ Caching Patterns

// Cache-Aside (Lazy Loading) - Most common
$user = Cache::remember("user:{$id}", 3600, function () use ($id) {
    return User::find($id);
});

// Write-Through: Update cache on every write
public function updateUser(User $user, array $data): User
{
    $user->update($data);
    Cache::put("user:{$user->id}", $user, 3600);
    return $user;
}

// Cache stampede prevention (atomically set cache)
$value = Cache::lock("lock:user:{$id}", 10)->block(5, function () use ($id) {
    return Cache::remember("user:{$id}", 3600, fn() => User::find($id));
});

// Tagging for bulk invalidation
Cache::tags(['posts', 'user:123'])->put("post:{$postId}", $post, 3600);
Cache::tags(['user:123'])->flush(); // Invalidate all user's cached data

3️⃣ Rate Limiting with Redis

// Sliding window rate limiter using Sorted Set
function checkRateLimit(string $key, int $limit, int $windowSeconds): bool
{
    $now = microtime(true);
    $windowStart = $now - $windowSeconds;
    
    $redis = Redis::connection();
    $redis->zRemRangeByScore($key, '-inf', $windowStart);
    $count = $redis->zCard($key);
    
    if ($count >= $limit) {
        return false; // Rate limited
    }
    
    $redis->zAdd($key, $now, $now);
    $redis->expire($key, $windowSeconds);
    return true;
}

// Laravel rate limiter
RateLimiter::for('api', function (Request $request) {
    return Limit::perMinute(60)->by($request->user()?->id ?: $request->ip());
});

4️⃣ Pub/Sub for Real-time

// Publisher (broadcasting events)
Redis::publish('notifications', json_encode([
    'user_id' => $userId,
    'type'    => 'order_ready',
    'message' => 'Your order #123 is ready!',
]));

// Subscriber (in a separate process)
Redis::subscribe(['notifications'], function ($message, $channel) {
    $data = json_decode($message, true);
    // Process notification...
    WebSocket::send($data['user_id'], $data);
});

5️⃣ Leaderboard with Sorted Sets

// Add/update player score
Redis::zAdd('leaderboard:weekly', $score, $userId);

// Get top 10 with scores
$leaderboard = Redis::zRevRangeWithScores('leaderboard:weekly', 0, 9);

// Get player rank
$rank = Redis::zRevRank('leaderboard:weekly', $userId);

// Get player score
$score = Redis::zScore('leaderboard:weekly', $userId);

6️⃣ Session Storage

SESSION_DRIVER=redis
SESSION_LIFETIME=120
REDIS_HOST=127.0.0.1
REDIS_PORT=6379
REDIS_PASSWORD=null

7️⃣ Redis Best Practices

• Always set TTL on cached keys — never use SET key value without expiry
• Use namespaced keys: app:users:123 not just user
• Monitor memory: redis-cli info memory
• Set maxmemory-policy allkeys-lru for cache-only Redis instances
• Use pipelining for bulk operations
• Enable persistence (RDB + AOF) for non-cache data
• Use Redis Cluster or Sentinel for HA

Outputs

1. Caching layer implementation
2. Rate limiting configuration
3. Session storage setup
4. Pub/sub patterns
5. Leaderboard/ranking implementation
6. Redis configuration for production