SendMessageCallback() - what is execution context of callback function

[Derell Licht]

I have a technique that I use in WinAPI programs, to avoid stalling the message queue. I start a separate thread in my program, which opens a hidden window with its own message queue. I typically call this thread the CommTask thread, since the first time I did this was to handle slow serial communications. When I want to perform a time-consuming task, I send a message to the CommTask thread using SendMessageCallback(), with a data packet telling it what to do. When the CommTask thread completes handling of my message, my callback function gets executed. What I don't know is, what thread is the callback function executing in?? Is it still in the CommTask thread, or has it somehow returned to my main program thread, or is there some other thread context that it executes in?

[CPallini]

The documentation[^] hints at calling thread context. In any case you may easily verify it calling GetCurrentThreadId[^] inside the callback function.

Veni, vidi, vici.

[Derell Licht]

Excellent idea!! Thank you, GetCurrentThreadId() will immediately and directly answer this question for me, I'll test it out this morning... Yep, GetCurrentThreadId() confirmed that the callback thread executes in the context of the initiating thread.