function DatabaseBackend::garbageCollection

Performs garbage collection on a cache bin.

The backend may choose to delete expired or invalidated items.

Overrides CacheBackendInterface::garbageCollection

File

core/lib/Drupal/Core/Cache/DatabaseBackend.php, line 366

Class

DatabaseBackend

Defines a default cache implementation.

Namespace

Code

public function garbageCollection() {
  try {
    // Bounded size cache bin, using FIFO.
    if ($this->maxRows !== static::MAXIMUM_NONE) {
      $first_invalid_create_time = $this->connection
        ->select($this->bin)
        ->fields($this->bin, [
        'created',
      ])
        ->orderBy("{$this->bin}.created", 'DESC')
        ->range($this->maxRows, 1)
        ->execute()
        ->fetchField();
      if ($first_invalid_create_time) {
        $this->connection
          ->delete($this->bin)
          ->condition('created', $first_invalid_create_time, '<=')
          ->execute();
      }
    }
    $this->connection
      ->delete($this->bin)
      ->condition('expire', Cache::PERMANENT, '<>')
      ->condition('expire', REQUEST_TIME, '<')
      ->execute();
  } catch (\Exception $e) {
    // If the table does not exist, it surely does not have garbage in it.
    // If the table exists, the next garbage collection will clean up.
    // There is nothing to do.
  }
}