private String getCurrentUser() {
    try {
      return UserGroupInformation.getCurrentUser().getShortUserName();
    } catch (IOException excp) {
    }
    return null;
  }
HiveMetaStoreAuthorizer :  Do authorization checks on MetaStore Events in MetaStorePreEventListener
ql/src/java/org/apache/hadoop/hive/ql/security/authorization/plugin/metastore/HiveMetaStoreAuthorizer.java