/**
* Refresh an existing lock by resetting its timeout.
*
* Performs a <tt>LOCK</tt> request as defined in the
* {@link http://tools.ietf.org/html/rfc4918#section-9.10.2 Section 9.10.2 of RFC-4918}.
*
* Note that the timeout value may be suggested when refreshing the lock, but that the server
* ultimately chooses the timeout value.
*
* @param string $uri
* Resource URI
* @param string $lockToken
* The lock token identifying the lock to be refreshed
* @param int $timeout
* Number of seconds remaining until lock expiration
*
* @return Lock Returns the refreshed lock on success, or <tt>null</tt> on failure
*/
public function refreshLock($uri, $lockToken, $timeout = null)
{
$headers = array('If' => "(<{$lockToken}>)");
if ($timeout) {
$headers['Timeout'] = (string) TimeoutHeader::parse($timeout);
}
$request = $this->createRequest('LOCK', $uri, $headers);
$response = $this->doRequest($request);
return $response->isSuccessful() ? Lock::parse($this, $response->getBody()) : null;
}
