check-caching-strategy

Caching Strategy Analysis

Analyze PHP code for caching opportunities and issues.

Detection Patterns

1. Missing Cache Opportunities

// CACHEABLE: Repeated expensive computation
public function getExchangeRate(string $currency): float
{
    return $this->api->fetchRate($currency); // API call each time
}

// CACHEABLE: Repeated database query
public function getSettings(): array
{
    return $this->repository->findAll(); // Same query repeatedly
}

// CACHEABLE: Configuration that rarely changes
public function getFeatureFlags(): array
{
    return $this->configLoader->load(); // File read each request
}

2. Cache Invalidation Issues

// STALE DATA: No invalidation
$cache->set('user_' . $id, $user, 3600);
// Later: user updated but cache not cleared

// STALE DATA: Time-based only
$cache->set('products', $products, 86400);
// Products change but cache lives for 24h

// RACE CONDITION: Invalidate before update
$this->cache->delete('user_' . $id);
$this->repository->update($user);
// Another request may cache old data between these lines

3. Over-Caching

// OVER-CACHED: User-specific data with long TTL
$cache->set('user_dashboard_' . $userId, $data, 86400);
// User dashboard may need fresh data

// OVER-CACHED: Rapidly changing data
$cache->set('stock_count_' . $productId, $count, 3600);
// Stock changes frequently

// OVER-CACHED: Huge cache entries
$cache->set('all_products', $allProducts); // 10MB cache entry

4. Cache Stampede

// STAMPEDE: Many requests rebuild cache simultaneously
public function getData(): array
{
    $data = $this->cache->get('key');
    if (!$data) {
        $data = $this->expensiveOperation(); // All concurrent requests hit this
        $this->cache->set('key', $data, 3600);
    }
    return $data;
}

// FIXED: Lock during rebuild
public function getData(): array
{
    $data = $this->cache->get('key');
    if (!$data) {
        $lock = $this->lockFactory->createLock('key_rebuild');
        if ($lock->acquire()) {
            $data = $this->expensiveOperation();
            $this->cache->set('key', $data, 3600);
            $lock->release();
        } else {
            $data = $this->cache->get('key'); // Wait for other process
        }
    }
    return $data;
}