UrlPreview::reserveIdForUrl

static function reserveIdForUrl($url)
{
	if ($metadata = UrlMetadataTable::getByUrl($url))
	{
		$id = $metadata['ID'];
	}
	else
	{
		$result = UrlMetadataTable::add(array(
				'URL' => $url,
				'TYPE' => UrlMetadataTable::TYPE_TEMPORARY
		));
		$id = $result->getId();
	}

	return $id;
}