message: Check server status first
diff: @@ -785,6 +785,13 @@ extern swServer* php_swoole_server_get_and_check_server(zval *zobject);
  static PHP_METHOD(swoole_websocket_server, disconnect)
  {
  + swServer *serv = php_swoole_server_get_and_check_server(ZEND_THIS);
  + if (sw_unlikely(!serv->gs->start))
  + {
  + php_swoole_fatal_error(E_WARNING, "server is not running");
  + RETURN_FALSE;
  + }
  +
  zend_long fd = 0;
  zend_long code = WEBSOCKET_CLOSE_NORMAL;
  char *data = NULL;
  @@ -799,16 +806,18 @@ static PHP_METHOD(swoole_websocket_server, disconnect)
  {
  RETURN_FALSE;
  }
  - SW_CHECK_RETURN(
  - swoole_websocket_server_close(
  - php_swoole_server_get_and_check_server(ZEND_THIS), fd, swoole_http_buffer, 1
  - )
  - );
  + SW_CHECK_RETURN(swoole_websocket_server_close(serv, fd, swoole_http_buffer, 1));
  }
  static PHP_METHOD(swoole_websocket_server, push)
  {
  swServer *serv = php_swoole_server_get_and_check_server(ZEND_THIS);
  + if (sw_unlikely(!serv->gs->start))
  + {
  + php_swoole_fatal_error(E_WARNING, "server is not running");
  + RETURN_FALSE;
  + }
  +
  zend_long fd = 0;
  zval *zdata = NULL;
  zend_long opcode = WEBSOCKET_OPCODE_TEXT;
  @@ -921,6 +930,12 @@ static PHP_METHOD(swoole_websocket_server, unpack)
  static PHP_METHOD(swoole_websocket_server, isEstablished)
  {
  swServer *serv = php_swoole_server_get_and_check_server(ZEND_THIS);
  + if (sw_unlikely(!serv->gs->start))
  + {
  + php_swoole_fatal_error(E_WARNING, "server is not running");
  + RETURN_FALSE;
  + }
  +
  zend_long fd;
  if (sw_unlikely(!serv->gs->start))
  