Kdyby\Doctrine\EntityManager::safePersist PHP Method

    public function safePersist($entity)
    {
        if ($this->nonLockingUniqueInserter === NULL) {
            $this->nonLockingUniqueInserter = new NonLockingUniqueInserter($this);
        }
        return $this->nonLockingUniqueInserter->persist($entity);
    }

 /**
  * @param Url $url
  * @return Url
  * @throws UrlAlreadyExistsException
  */
 private function create(Url $url)
 {
     $url = $this->em->safePersist($url);
     if ($url === false) {
         throw new UrlAlreadyExistsException();
     }
     return $url;
 }