ensureAnonymousSession example

  public function setIfNotExists($key, $value) {
    $value = (object) [
      'owner' => $this->owner,
      'data' => $value,
      'updated' => (int) $this->requestStack->getMainRequest()->server->get('REQUEST_TIME'),
    ];
    $this->ensureAnonymousSession();
    $set = $this->storage->setWithExpireIfNotExists($key, $value, $this->expire);
    return $set;
  }

  /** * Stores a particular key/value pair in this SharedTempStore. * * Only stores the given key/value pair if it does not exist yet or is owned * by $this->owner. * * @param string $key * The key of the data to store. * @param mixed $value * The data to store. * * @return bool * TRUE if the data was set, or FALSE if it already exists and is not owned * by $this->user. * * @throws \Drupal\Core\TempStore\TempStoreException * Thrown when a lock for the backend storage could not be acquired. */