Class rpc_libc_server

less_slow.cpp:6755–6794

* @brief A minimal RPC @b server using LibC functionality to setup the UDP socket, * and synchronous blocking POSIX calls to receive and send packets - * @b one at a time! */

 *          @b one at a time!
 */
class rpc_libc_server {
    int socket_descriptor_;
    sockaddr_in server_address_;
    std::atomic_bool should_stop_;

  public:
    rpc_libc_server(std::string const &server_address_str, std::uint16_t port, std::size_t max_concurrency)
        : should_stop_(false) {
        auto [socket_descriptor, server_address] = rpc_server_socket(port, server_address_str);
        socket_descriptor_ = socket_descriptor;
        server_address_ = server_address;

        // Let's make sure we don't block forever on `recvfrom`
        struct timeval duration;
        duration.tv_sec = 0;
        duration.tv_usec = to_microseconds(rpc_batch_timeout_k).count();
        if (setsockopt(socket_descriptor_, SOL_SOCKET, SO_RCVTIMEO, &duration, sizeof(duration)) < 0)
            raise_system_error("Failed to set sockets batch timeout");
    }

    ~rpc_libc_server() noexcept {}
    void close() noexcept { ::close(socket_descriptor_); }
    void stop() noexcept { should_stop_.store(true, std::memory_order_seq_cst); }

    void operator()() noexcept {
        sockaddr_in client_address;
        socklen_t client_len = sizeof(client_address);
        rpc_buffer_t receive_buffer, send_buffer;

        while (!should_stop_.load(std::memory_order_seq_cst)) {
            ssize_t received_length = recvfrom(socket_descriptor_, receive_buffer.data(), receive_buffer.size(), 0,
                                               reinterpret_cast<sockaddr *>(&client_address), &client_len);
            if (received_length <= 0) continue;
            std::size_t reply_length =
                packet_modify(receive_buffer.data(), static_cast<std::size_t>(received_length), send_buffer.data());
            sendto(socket_descriptor_, send_buffer.data(), reply_length, 0,
                   reinterpret_cast<sockaddr *>(&client_address), client_len);
        }
    }
};

/**
 *  @brief  A minimal RPC @b client using LibC functionality to setup the UDP socket,