Method closeAsync

core/network/WebSocket.cpp:493–505

* @brief Closes the connection to server asynchronously. * @note It's an asynchronous method, it just notifies websocket thread to exit and returns directly, * If using 'closeAsync' to close websocket connection, * be careful of not using destructed variables in the callback of 'onClose'. */

 *        be careful of not using destructed variables in the callback of 'onClose'.
 */
void WebSocket::closeAsync(uint16_t code, std::string_view reason)
{
    if (_state < State::CLOSING)
    {
        if (_service->is_open(0))
        {
            _state = State::CLOSING;
            _service->close(0);
        }
        else
            _state = State::CLOSED;
    }
}

void WebSocket::generateHandshakeSecKey()
{