|  | 
Close the acceptor.
void close(
    asio::error_code & ec);
This function is used to close the acceptor. Any asynchronous accept operations will be cancelled immediately.
            A subsequent call to open() is required before the acceptor
            can again be used to again perform socket accept operations.
          
Set to indicate what error occurred, if any.
asio::ip::tcp::acceptor acceptor(my_context);
...
asio::error_code ec;
acceptor.close(ec);
if (ec)
{
  // An error occurred.
}