states

use Drupal\Core\State\StateInterface;
  /**
  * The state store.
  *
  * @var \Drupal\Core\State\StateInterface
  */
 protected $state;
  /**
  * Drush command constructor.
  *
  * @param \Drupal\Core\State\StateInterface $state
  *   T

Reading State

A single value.

$val = \Drupal::state()->get('key');

Multiple key/value pairs.

$pairs = \Drupal::state()->getMultiple($keys);

Writing State

A single value.

\Drupal::state()->set('key','value');

Multiple values.