/**
* Releases any lock that exists on this document.
*
* @param object $document
*/
public function unlock($document)
{
$criteria = array('_id' => $this->uow->getDocumentIdentifier($document));
$lockMapping = $this->class->fieldMappings[$this->class->lockField];
$this->collection->update($criteria, array($this->cmd.'unset' => array($lockMapping['name'] => true)));
$this->class->reflFields[$this->class->lockField]->setValue($document, null);
}