c++ - How to pass a boost asio tcp socket to a thread for sending heartbeat to client or server

Question

I am writing a client/server program in boost TCP in which I want to send a HEARTBEAT message to the client every 2 seconds for which I am trying to create a new thread by which I can send it easily but unable to solve it. I am creating thread using boost::thread t(hearbeatSender,sock); this. but giving lots of errors. I also use bind to bind function name with the socket but not resolved the error.

void process(boost::asio::ip::tcp::socket & sock);
std::string read_data(boost::asio::ip::tcp::socket & sock);
void write_data(boost::asio::ip::tcp::socket & sock,std::string);
void hearbeatSender(boost::asio::ip::tcp::socket & sock);
int main()
{

    unsigned short port_num = 3333;
    boost::asio::ip::tcp::endpoint ep(boost::asio::ip::address_v4::any(), port_num);
    boost::asio::io_service io;
    try
    {
        boost::asio::ip::tcp::acceptor acceptor(io, ep.protocol());
        acceptor.bind(ep);
        acceptor.listen();
        boost::asio::ip::tcp::socket sock(io);
        acceptor.accept(sock);
        boost::thread t(hearbeatSender,sock); 
        process(sock);
        t.join();

    }
    catch (boost::system::system_error &e)
    {
        std::cout << "Error occured! Error code = " << e.code()
        << ". Message: " << e.what();

        return e.code().value();
    }
  return 0;

}
void process(boost::asio::ip::tcp::socket & sock)
{
    while(1){
    std::string data = read_data(sock);
    std::cout<<"Client's request is: "<<data<<std::endl;
    write_data(sock,data);
    }
}
std::string read_data(boost::asio::ip::tcp::socket & sock)
{
    boost::asio::streambuf buf;
    boost::asio::read_until(sock, buf, "
");
    std::string data = boost::asio::buffer_cast<const char*>(buf.data());
    return data;
}
void write_data(boost::asio::ip::tcp::socket & sock,std::string data)
{
    boost::system::error_code error;
    std::string msg;
    int ch = data[0]-'0';
    switch(ch)
    {
        case 1: msg = "Case 1
"; break;
        case 2: msg = "Case 2
"; break;
        case 3: msg = "Case 3
"; break;
        case 4: msg = "Case 4
"; break;
        default: msg  = "Case default
"; break;
    }
    boost::asio::write( sock, boost::asio::buffer(msg+ "
"), error );
     if( !error ) {
        std::cout << "Server sent hello message!" << std::endl;
     }
     else {
        std::cout << "send failed: " << error.message() << std::endl;
     }
}
void hearbeatSender(boost::asio::ip::tcp::socket & sock)
{
    boost::system::error_code error;
    std::string msg = "HEARTBEAT";
    while(1)
    {
        sleep(2);
        std::cout<<msg<<std::endl;
        boost::asio::write( sock, boost::asio::buffer(msg+ "
"), error );
        if( !error ) {
        std::cout << "Server sent HEARTBEAT message!" << std::endl;
        }
        else {
            std::cout << "send failed: " << error.message() << std::endl;
        }
    }
}

This is a server-side code for responding to the message of the client and sending heartbeat to the client. This is a synchronous TCP server.

Answer 1

Instead of this:

    boost::asio::ip::tcp::socket sock(io);
    acceptor.accept(sock);
    boost::thread t(hearbeatSender,sock); 

this:

    auto sock = acceptor.accept();
    std::thread t([&sock]() {
        hearbeatSender(sock);
    });

And instead of sleep, just used std::this_thread::sleep for compiling universally.

Here's the complete program that compiles and runs

#include <boost/asio.hpp>
#include <iostream>


void process(boost::asio::ip::tcp::socket& sock);
std::string read_data(boost::asio::ip::tcp::socket& sock);
void write_data(boost::asio::ip::tcp::socket& sock, std::string);
void hearbeatSender(boost::asio::ip::tcp::socket& sock);
int main()
{

    unsigned short port_num = 3333;
    boost::asio::ip::tcp::endpoint ep(boost::asio::ip::address_v4::any(), port_num);
    boost::asio::io_service io;
    try
    {
        boost::asio::ip::tcp::acceptor acceptor(io, ep.protocol());
        acceptor.bind(ep);
        acceptor.listen();
        auto sock = acceptor.accept();
        std::thread t([&sock]() {
            hearbeatSender(sock);
        });
        process(sock);
        t.join();

    }
    catch (boost::system::system_error& e)
    {
        std::cout << "Error occured! Error code = " << e.code()
            << ". Message: " << e.what();

        return e.code().value();
    }
    return 0;

}
void process(boost::asio::ip::tcp::socket& sock)
{
    while (1) {
        std::string data = read_data(sock);
        std::cout << "Client's request is: " << data << std::endl;
        write_data(sock, data);
    }
}
std::string read_data(boost::asio::ip::tcp::socket& sock)
{
    boost::asio::streambuf buf;
    boost::asio::read_until(sock, buf, "
");
    std::string data = boost::asio::buffer_cast<const char*>(buf.data());
    return data;
}
void write_data(boost::asio::ip::tcp::socket& sock, std::string data)
{
    boost::system::error_code error;
    std::string msg;
    int ch = data[0] - '0';
    switch (ch)
    {
    case 1: msg = "Case 1
"; break;
    case 2: msg = "Case 2
"; break;
    case 3: msg = "Case 3
"; break;
    case 4: msg = "Case 4
"; break;
    default: msg = "Case default
"; break;
    }
    boost::asio::write(sock, boost::asio::buffer(msg + "
"), error);
    if (!error) {
        std::cout << "Server sent hello message!" << std::endl;
    }
    else {
        std::cout << "send failed: " << error.message() << std::endl;
    }
}
void hearbeatSender(boost::asio::ip::tcp::socket& sock)
{
    boost::system::error_code error;
    std::string msg = "HEARTBEAT";
    while (1)
    {
        std::this_thread::sleep_for(std::chrono::seconds(2));
        std::cout << msg << std::endl;
        boost::asio::write(sock, boost::asio::buffer(msg + "
"), error);
        if (!error) {
            std::cout << "Server sent HEARTBEAT message!" << std::endl;
        }
        else {
            std::cout << "send failed: " << error.message() << std::endl;
        }
    }
}