boost::asio ioservice holds the rest of my code run - c++

Question

i have created a windows appliation and i have used some QT Gui in that to display a Widget, so now i want to add boost::asio async TCP code to receive and send the data to another application.
when i write below code in my main(), this is what happens
//Code to initialize QT widgets and working fine.
try
{
boost::asio::io_service io_service;
server s(io_service, 8888); //8888 is a port no.
io_service.run(); // **Even after successfull creation it doesn't look for incoming data**
}
catch(std::exception& e)
{
std::cout << "Exception : " << e.what() << std::endl;
}
//rest of the code for qt widget, which will be blocked by io_service.
i have tried poll() as well to avoid this but it is also not wait for any incoming data.
is there any way to achieve both at a time??
Regards,
Jithendra.

Answer 1

io_service requires a thread of its own to not block other operations. also, instead of starting a thread on run(), there's an object called boost::asio::io_service::work that ensures run() is always executed, even when it returns.
here's how I usually implement io_service to run:
IoServiceWork.h:
#include <boost/asio.hpp>
#include <boost/thread/thread.hpp>
class IoServiceWork
{
public:
IoServiceWork()
: m_ioService(new boost::asio::io_service()),
m_ioServiceWork(new boost::asio::io_service::work(*m_ioService)),
m_ioWorkThread(new boost::thread(boost::bind(&boost::asio::io_service::run, m_ioService)))
{
}
~IoServiceWork()
{
delete m_ioServiceWork;
m_ioWorkThread->join();
delete m_ioWorkThread;
delete m_ioService;
}
boost::asio::io_service& ioService()
{
return *m_ioService;
}
boost::asio::io_service* m_ioService;
boost::asio::io_service::work* m_ioServiceWork;
boost::thread* m_ioWorkThread;
};
Then I access my static global io_service object from any .cpp file from my project using this function.
CustomIOService.h:
#include <boost/asio.hpp>
boost::asio::io_service& IOService();
CustomIOService.cpp:
#include "IoServiceWork.h"
boost::asio::io_service& IOService()
{
static IoServiceWork ioServiceWork;
return ioServiceWork.ioService();
}
it is put as a static object in a function to avoid the static initialization order fiasco.
So, then, all you have to do to create your socket, or any object requiring an io_service object, such as server in your case:
#include <CustomIoService.h>
server s(IOService(), 8888);