FileParsingCacheCollectorBase.php

<?php

declare (strict_types=1);
namespace Drupal\Core\Utility;

use Drupal\Component\Datetime\TimeInterface;
use Drupal\Core\Cache\CacheBackendInterface;
use Drupal\Core\Cache\CacheCollector;
use Drupal\Core\Lock\LockBackendInterface;

/**
 * Caches file parsing in a cache collector.
 */
abstract class FileParsingCacheCollectorBase extends CacheCollector {
  public function __construct($cid, CacheBackendInterface $cache, LockBackendInterface $lock, protected TimeInterface $time, array $tags = []) {
    parent::__construct($cid, $cache, $lock, $tags);
  }
  
  /**
   * {@inheritdoc}
   */
  public function get($key) : array {
    $this->lazyLoadCache();
    if (isset($this->storage[$key]) && file_exists($key)) {
      if ($this->storage[$key]['mtime'] === filemtime($key)) {
        return $this->storage[$key]['parsed'];
      }
    }
    return $this->resolveCacheMiss($key);
  }
  
  /**
   * {@inheritdoc}
   */
  public function resolveCacheMiss($key) : array {
    if (file_exists($key)) {
      $mtime = filemtime($key);
      $this->storage[$key] = [
        'mtime' => $mtime,
        'parsed' => $this->parseFile(file_get_contents($key)) ?? [],
      ];
      $this->persist($key);
      return $this->storage[$key]['parsed'];
    }
    if (isset($this->storage[$key])) {
      $this->delete($key);
    }
    return [];
  }
  
  /**
   * {@inheritdoc}
   */
  public function updateCache($lock = TRUE) : void {
    // Look for files cached longer than three months ago and remove them from
    // the cache item if they no longer exist.
    $three_months_ago = $this->time
      ->getCurrentTime() - 90 * 86400;
    foreach ($this->storage as $key => $item) {
      if ($item['mtime'] <= $three_months_ago && !file_exists($key)) {
        $this->delete($key);
      }
    }
    parent::updateCache($lock);
  }
  
  /**
   * Parses a file given a filename and returns the result.
   *
   * @param string $file
   *   The file path.
   *
   * @return mixed
   *   The result of the file parsing.
   */
  abstract protected function parseFile(string $file) : mixed;

}