Code snippet that can be used to get Currently logged in user's roles in drupal 8.
$current_user = \Drupal::currentUser();
$roles = $current_user->getRoles();
if (in_array('editor', $roles)) {
// your code
}
$roles is an array like:
Array
(
[0] => authenticated
[1] => administrator
[2] => some_other_role
)
