o11y-8.x-1.x-dev/modules/o11y_metrics/modules/o11y_metrics_cache/src/Cache/CacheMetricsCacheTagsInvalidator.php

<?php

namespace Drupal\o11y_metrics_cache\Cache;

use Drupal\Core\Cache\CacheTagsInvalidatorInterface;
use Symfony\Component\HttpFoundation\RequestStack;
use Drupal\o11y_metrics\Bridge\PrometheusBridgeInterface;
use Drupal\o11y_metrics\BaseMetricsSourceInterface;

/**
 * Provides metrics about tag invalidations.
 */
class CacheMetricsCacheTagsInvalidator implements CacheTagsInvalidatorInterface, BaseMetricsSourceInterface {

  /**
   * The promphp bridge.
   *
   * @var \Drupal\o11y_metrics\Bridge\PrometheusBridgeInterface
   */
  protected $promBridge;

  /**
   * Is this class enabled or not.
   *
   * @var bool
   */
  protected $isEnabled;

  /**
   * The request_stack service.
   *
   * @var \Symfony\Component\HttpFoundation\RequestStack
   */
  protected $requestStack;

  /**
   * A list of tags that have already been invalidated in this request.
   *
   * Used to prevent the recording of the same cache tag multiple times.
   *
   * @var string[]
   */
  protected $invalidatedTags = [];

  /**
   * CacheMetricsCacheTagsInvalidator constructor.
   *
   * @param \Drupal\o11y_metrics\Bridge\PrometheusBridgeInterface $promBridge
   *   The promphp bridge.
   * @param \Symfony\Component\HttpFoundation\RequestStack $requestStack
   *   The request_stack service.
   * @param bool $isEnabled
   *   Whether this class should do anything or not.
   */
  public function __construct(
    PrometheusBridgeInterface $promBridge,
    RequestStack $requestStack,
    bool $isEnabled
  ) {
    $this->promBridge = $promBridge;
    $this->requestStack = $requestStack;
    $this->isEnabled = $isEnabled;
  }

  /**
   * {@inheritdoc}
   */
  public static function getMetricsSourceId(): string {
    return 'cache_invalidations';
  }

  /**
   * Log all Invalidations.
   *
   * @param string[] $tags
   *   The list of tags for which to invalidate cache items.
   */
  public function invalidateTags(array $tags) {
    if (!$this->isEnabled) {
      return;
    }
    $request = $this->requestStack->getCurrentRequest();
    foreach ($tags as $tag) {
      // Only invalidate tags once per request unless they are written again.
      if (isset($this->invalidatedTags[$tag])) {
        continue;
      }
      $this->invalidatedTags[$tag] = TRUE;
      $namespace_name_help = [
        'drupal',
        'cache_total_tag_invalidations',
        'Total number of cache tag invalidations.',
      ];
      $this->promBridge->getCounter(...$namespace_name_help, ...[[], $this])->inc();
      $namespace_name_help[1] = 'cache_total_tag_invalidations_per_tag';
      $this->promBridge->getCounter(
        ...$namespace_name_help,
        ...[['tag'], $this]
      )->inc([$tag]);
      $namespace_name_help[1] = 'cache_total_tag_invalidations_per_tag_and_request';
      $this->promBridge->getCounter(
        ...$namespace_name_help,
        ...[['tag', 'request'], $this]
      )->inc([
        $tag,
        $request->getBaseUrl() . $request->getPathInfo(),
      ]);
    }
  }

}