Question

I have two different threads. the first one is the main thread that must handle the gui operations. the second one is a network thread which listens the related tcp ports. I need network thread to invoke methods in a way that they will run in the main thread. how can I achieve this without using a message queue mechanism?

Answer 1

How I would do it in your case is to is tell the other thread to schedule a function on its event queue. Arguments to that function are bound in with the function that is sent.

Like for example in the network code:

int result = doWork();
otherThreadsEventLoop.scheduleFunction(drawResult,result);

All GUI frameworks and most networking frameworks allow you to do that.

• If you are using qt, then QMetaObject::invokeMethod is what you would use.
• If you are using gtk, then q_idle_add is what you would use.
• If you are using boost::asio, then io_service.post is what you would use.
• If you are using libevent, then event_base_once is what you would use.

One issue might be the binding of additional parameters for libraries that only give you C callbacks. My suggestion is to write a “wrapper” function that allows you to pass std::functions into the callback.