# Cache

The container binds PSR-16 CacheInterface to a Symfony cache pool. Configuring REDIS_URL selects Redis; otherwise the pool uses private filesystem storage. Inject the interface rather than a concrete implementation.

## Store and retrieve

```php
use Psr\SimpleCache\CacheInterface;

$cache->set('homepage.summary', ['posts' => 12], 300);
$summary = $cache->get('homepage.summary', []);
$cache->delete('homepage.summary');
```

TTL values are seconds, DateInterval objects, or null. Use application-controlled keys; PSR-16 reserves some characters.

## In a handler

```php
$router->get('/summary', function (CacheInterface $cache) {
    return $cache->get('homepage.summary', ['posts' => 0]);
});
```

## Clear application cache

```bash
php elang cache:clear
```

The command clears the application cache pool. Twig's compiled templates are separate and automatically reload when source files change. For multiple application hosts, configure the same Redis endpoint and application prefix; custom cache bindings remain available for other backends.