- speed up the whole session cleaning in kill_session()

program/include/rcmail.php

@@ -793,8 +793,7 @@ class rcmail
    */
   public function kill_session()
   {
-    foreach (array_keys($_SESSION) as $var)
-      rcube_sess_unset($var);
+    rcube_sess_unset();
     $_SESSION = array('language' => $this->user->language, 'auth_time' => time(), 'temp' => true);
     rcmail::setcookie('sessauth', '-del-', time() - 60);
     $this->user->reset();

program/include/session.inc

@@ -87,10 +87,13 @@ function rcube_sess_write($key, $vars)
 
 
 // unset session variable
-function rcube_sess_unset($var)
+function rcube_sess_unset($var=NULL)
 {
   $DB = rcmail::get_instance()->get_dbh();
 
+  if (empty($var))
+    return rcube_sess_destroy(session_id());
+
   $now = $DB->fromunixtime(time());
 
   $sql_result = $DB->query(