/**
* Tries to obtain a lock with a name given by the string $lockname,
* using a timeout of $timeout seconds. Returns 1 if the lock was obtained
* successfully, 0 if the attempt timed out
* (for example, because another client has previously locked the name),
* or NULL if an error occurred
* If a name has been locked by one client, any request by another client
* for a lock with the same name is blocked.
*
* @param string $lockname
* @param number $timeout in seconds
* @throws UnexpectedValueException if there is already an active lock
* @return integer 1 if the lock was obtained successfully, 0 if the attempt timed out
*/
public static function get($lockname, $timeout = 10)
{
if (self::$current !== null) {
throw new UnexpectedValueException(sprintf('could not acquire new lock, %s still active'));
}
$ok = DBManager::get()->fetchColumn("SELECT GET_LOCK(?,?)", array(self::lockname($lockname), $timeout));
if ($ok) {
self::$current = $lockname;
}
return $ok;
}
