According to the doc of boost 1.68, old io_context::post is deprecated. boost::asio::post() is recomanded. Can anyone give me an example?

Question

I want to use the feature of asio::io_context::post. But I found it was marked as DEPRECATED

You can see it here (Deprecated: Use boost::asio::post().) Request the io_context to invoke the given handler and return immediately.

Then I want to have a try on boost::asio::post(), but I can't image how to write the code. No example, no code, even no more docs.

Can you help me? Thanks a lot.

Answer 1

I have a real example from my RTSP server using boost.asio:

using udp_buffer = std::array<char, 0xFFFF>;
using shared_udp_socket = std::tuple<boost::asio::ip::udp::socket,
                boost::asio::io_context::strand,
                udp_buffer,
                boost::asio::ip::udp::endpoint>;

void rtsp::rtsp_server::handle_incoming_udp_traffic(const boost::system::error_code &error,
                                                    std::size_t received_bytes,
                                                    rtsp::rtsp_server::shared_udp_socket &incoming_socket) {
    if (error)
        throw std::runtime_error{error.message()};

    auto data = std::make_shared<std::vector<char>>();

    std::copy_n(std::get<2>(incoming_socket).cbegin(), received_bytes, std::back_inserter(*data));
    boost::asio::ip::udp::endpoint received_from_endpoint = std::get<3>(incoming_socket);

    boost::asio::post(std::get<1>(incoming_socket).get_io_context(),
                      std::bind(&rtsp::rtsp_server::handle_new_incoming_message,
                                data, std::ref(incoming_socket),
                                received_from_endpoint,
                                std::ref(this->server_state_))
    );

    start_async_receive(incoming_socket);
}
void rtsp::rtsp_server::handle_new_incoming_message(std::shared_ptr<std::vector<char>> message,
                                                shared_udp_socket &socket_received_from,
                                                boost::asio::ip::udp::endpoint received_from_endpoint,
                                                server::rtsp_server_state &server_state {...}

There you can see how I use boost::asio::post to post the handling of the incoming UDP datagram to the iocontext, while starting to relisten to new incoming datagrams on the udp socket via start_async_receive. If you need further explanation, let me know.