Move container to memcache

Hi, now on Drupal core the cache.container is using the database cache also when you have set it on the cache.container, the solution around this is set directly on $settings['bootstrap_container_definition'] definition, but now the DrupalMemcacheFactory don't have a static method that we can use to get the DrupalBackEnd instance...

  $loader = new \Composer\Autoload\ClassLoader();
  $loader->addPsr4('Drupal\\memcache\\', 'modules/contrib/memcache/src');
  $loader->register();

  $settings['bootstrap_container_definition'] = [
    'parameters' => [],
    'services' => [
      'database' => [
        'class' => 'Drupal\Core\Database\Connection',
        'factory' => 'Drupal\Core\Database\Database::getConnection',
        'arguments' => ['default'],
      ],
      'settings.container' => [
        'class' => 'Drupal\Core\Site\Settings',
        'factory' => 'Drupal\Core\Site\Settings::getInstance',
      ],
      'memcache.config.container' => [
        'class' => 'Drupal\memcache\DrupalMemcacheConfig',
        'arguments' => ['@settings.container'],
      ],
      'memcache.backend.cache.container' => [
        'class' => 'Drupal\memcache\DrupalMemcacheFactory',
        'factory' => 'Drupal\memcache\DrupalMemcacheFactory::getInstance',
        'arguments' => ['@memcache.config.container'],
      ],
      'lock.container' => [
        'class' => 'Drupal\memcache\Lock\MemcacheLockBackend',
        'arguments' => ['container', '@memcache.backend.cache.container'],
      ],
      'cache.container' => [
        'class' => 'Drupal\memcache\MemcacheBackend',
        'arguments' => ['container', '@memcache.backend.cache.container', '@lock.container', '@memcache.config.container', '@cache_tags_provider.container'],
      ],
      'cache_tags_provider.container' => [
        'class' => 'Drupal\Core\Cache\DatabaseCacheTagsChecksum',
        'arguments' => ['@database'],
      ],
    ]
  ];

This should be the code to override it, but we don't have that static method. My suggestion is to create the static method inside the DrupalMemcacheFactory class, What you guys think about it?

Which that we can just override the cache container using memcache

The code for the static method should be like this

  /**
   * Get the right memcache drupal class.
   *
   * @param \Drupal\memcache\DrupalMemcacheConfig $settings
   * @return \Drupal\memcache\DrupalMemcache|\Drupal\memcache\DrupalMemcached
   */
  public static function getInstance(DrupalMemcacheConfig $settings) {
    $preferred = $settings->get('extension', NULL);
    if (isset($preferred) && class_exists($preferred)) {
      $extension= $preferred;
    }
    // If no extension is set, default to Memcache. The Memcached extension has
    // some features that the older extension lacks but also an unfixed bug that
    // affects cache clears.
    // @see http://pecl.php.net/bugs/bug.php?id=16829
    elseif (class_exists('Memcache')) {
      $extension = 'Memcache';
    }
    elseif (class_exists('Memcached')) {
      $extension = 'Memcached';
    }
    else {
      throw new MemcacheException('No Memcache extension found');
    }

    // Create a new Memcache object. Each cluster gets its own Memcache
    // object.
    // @todo Can't add a custom memcache class here yet.
    if ($extension == 'Memcached') {
      return new DrupalMemcached($settings);
    }

    return new DrupalMemcache($settings);
  }

I cannot instantiate the class directly because I need to make the decision between the Memcache or memcached...