message: Prohibited to execute swoole_mysql::close in the onClose callback.
diff: @@ -1031,6 +1031,12 @@ static PHP_METHOD(swoole_mysql, close)
  RETURN_FALSE;
  }
  + if (client->cli->socket->closing)
  + {
  + swoole_error_log(SW_LOG_NOTICE, SW_ERROR_SESSION_CLOSING, "The mysql connection[%d] is closing.", client->fd);
  + RETURN_FALSE;
  + }
  +
  zend_update_property_bool(swoole_mysql_class_entry_ptr, getThis(), ZEND_STRL("connected"), 0 TSRMLS_CC);
  SwooleG.main_reactor->del(SwooleG.main_reactor, client->fd);
  @@ -1044,6 +1050,7 @@ static PHP_METHOD(swoole_mysql, close)
  zval *object = getThis();
  if (client->onClose)
  {
  + client->cli->socket->closing = 1;
  args[0] = &object;
  if (sw_call_user_function_ex(EG(function_table), NULL, client->onClose, &retval, 1, args, 0, NULL TSRMLS_CC) != SUCCESS)
  {
  