CacheControlEventSubscriber.php in HTTP Cache Control 8.2

Namespace

Drupal\http_cache_control\EventSubscriber

File

src/EventSubscriber/CacheControlEventSubscriber.php

<?php

namespace Drupal\http_cache_control\EventSubscriber;

use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\HttpKernel\KernelEvents;
use Symfony\Component\HttpKernel\Event\FilterResponseEvent;
use Drupal\Core\Site\Settings;
use Drupal\Core\Config\ConfigFactory;

/**
 * Subscriber for adding http cache control headers.
 */
class CacheControlEventSubscriber implements EventSubscriberInterface {

  /**
   * Configuration Factory.
   *
   * @var \Drupal\Core\Config\ConfigFactory
   */
  protected $configFactory;

  /**
   * Constructor.
   */
  public function __construct(ConfigFactory $configFactory) {
    $this->configFactory = $configFactory;
  }

  /**
   * Set http cache control headers.
   */
  public function setHeaderCacheControl(FilterResponseEvent $event) {
    $config = $this->configFactory
      ->get('http_cache_control.settings');
    $response = $event
      ->getResponse();
    if ($variation = $config
      ->get('cache.http.vary')) {
      $vary = $response
        ->getVary();
      foreach (array_map('trim', explode(',', $variation)) as $header) {
        $vary[] = $header;
      }
      if (!Settings::get('omit_vary_cookie')) {
        $vary[] = 'Cookie';
      }
      $response
        ->setVary(implode(',', $vary));
    }
    if (!$response
      ->isCacheable()) {
      return;
    }
    $ttl = $response
      ->getMaxAge();
    switch ($response
      ->getStatusCode()) {
      case 404:
        $ttl = $config
          ->get('cache.http.404_max_age', $ttl);
        break;
      case 302:
        $ttl = $config
          ->get('cache.http.302_max_age', $ttl);
        break;
      case 301:
        $ttl = $config
          ->get('cache.http.301_max_age', $ttl);
        break;
    }
    if ($ttl != $response
      ->getMaxAge()) {
      $response
        ->setClientTtl($ttl);
      $response
        ->setSharedMaxAge($ttl);
    }
    elseif ($ttl = $config
      ->get('cache.http.s_maxage')) {
      $response
        ->setSharedMaxAge($ttl);
    }
    if ($response
      ->getStatusCode() >= 500) {
      $response
        ->setSharedMaxAge($config
        ->get('cache.http.5xx_max_age'));
    }
    elseif ($response
      ->getStatusCode() < 400) {

      // Add stale-if-error directive.
      if ($seconds = $config
        ->get('cache.http.stale_if_error')) {
        $response->headers
          ->addCacheControlDirective('stale-if-error', $seconds);
      }

      // Add stale-while-revalidate directive.
      if ($seconds = $config
        ->get('cache.http.stale_while_revalidate')) {
        $response->headers
          ->addCacheControlDirective('stale-while-revalidate', $seconds);
      }

      // Surrogate Control
      $maxage = $config
        ->get('cache.surrogate.maxage');
      $nostore = $config
        ->get('cache.surrogate.nostore');
      if (!empty($maxage) || $nostore) {
        $value = $nostore ? [
          'no-store',
        ] : [];
        if (!empty($maxage)) {
          $value[] = 'max-age=' . $maxage;
        }
        $response->headers
          ->set('Surrogate-Control', implode(', ', $value));
      }
    }
  }

  /**
   * {@inheritdoc}
   */
  public static function getSubscribedEvents() {

    // Response: set header content for security policy.
    $events[KernelEvents::RESPONSE][] = [
      'setHeaderCacheControl',
      -10,
    ];
    return $events;
  }

}

Classes

Name	Description
CacheControlEventSubscriber	Subscriber for adding http cache control headers.