  sst_thread_arg (const char* c, char** e)
    : cmd(c), env(e), ret_str(0), err(-1)
  {
    mysql_mutex_init(key_LOCK_wsrep_sst_thread, &lock, MY_MUTEX_INIT_FAST);
    mysql_cond_init(key_COND_wsrep_sst_thread, &cond, NULL);
  }