public boolean authorizeUserGlobal(User user, Permission.Action action) {
    if (user == null) {
      return false;
    }
    if (Superusers.isSuperUser(user)) {
      return true;
    }
    if (authorizeGlobal(globalCache.get(user.getShortName()), action)) {
      return true;
    }
    for (String group : user.getGroupNames()) {
      if (authorizeGlobal(globalCache.get(AuthUtil.toGroupEntry(group)), action)) {
        return true;
      }
    }
    return false;
  }
Check if user has given action privilige in global scope.
@param user   user name
@param action one of action in [Read, Write, Create, Exec, Admin]
@return true if user has, false otherwise
hbase-server/src/main/java/org/apache/hadoop/hbase/security/access/AuthManager.java