Writing a Chat Application in C++

pokemon123

Hello,
I am trying to make a chat application. I use Qt (for the GUI) and Boost.Asio (for socket programming function calls).
I want to establish a connection between the client and server before I show the client's GUI. However, when I set up the connection, I use a function called io_service.run() which is a blocking call. Basically, it is an event loop queueing and executing read and write messages. Since this is a blocking call, it will not reach a.exec() which shows the GUI. So I end up with a black window, instead of the GUI.

How do I fix this?
Thank you. :)

Pl45m4

@pokemon123

Why you want to use Asio? You can do the whole Chat App (GUI + network connection) with Qt only.
https://doc.qt.io/qt-5/qtnetwork-network-chat-example.html

a.exec() will start its own event loop for GUI, so it's not that easy to make io_service.run() work with Qt.

You could try to run your io_service in a different boost::thread, but I don't know, if everything will work as expected

KH-219Design

Another option (if you are bound and determined to use as few threads as humanly possible, for whatever reason you may have):

You can use a QTimer that "ticks" every N milliseconds (you choose N), and you can invoke other methods on your io_service instance instead of invoking run(). For example you could use io_service::run_for to constrain the length of "timeslice" you yield to the io_service.

There are a number of similar methods, such as run_one, poll, and poll_one.

In this way, you can achieve a sort of cooperative, voluntary yielding, time-slicing where the io_service uses the main/GUI thread, but it never blocks it for very long.