CODEWITHSUNDEEP
windowsmultithreadingwinapipthreads
Steven Lu
Steven Lu

Reputation: 43427

Using Win32 API functionality along with/from pthreads

I have my own threading library built using TinyThread++. It works quite well, and it was also a great learning experience for me. I have my own datastructures for passing around messages, and the interface makes good sense to me, primarily because I was its author.

Whenever a thread is created in my system, it runs in a loop, and checks for messages occasionally via a message passing protocol of my own devising.

Now I want to start using some Windows API functionality, and windows has its own set of conventions and message queues, etc. Now I'm pretty sure that TinyThread++ uses pthreads. Since I'm using MinGW, I'm wondering if pthreads is being implemented on windows threads. If this is the case, I may be able to just treat my pthreads-threads as windows-threads. But if not, I suspect I might run into some strange behavior.

edit: looking at the thread type given by Tinythread++ it looks like it actually uses the windows HANDLE to keep track of the threads and even uses _beginthreadex to spawn them.

My question is, will Windows be happy if I go around calling SetWindowsHookEx from some point in my pthreads code? I realize I need to have a Windows message polling loop in the same thread. I intend to do something like this: 

try {

    HHOOK mousehook = SetWindowsHookEx(WH_MOUSE_LL, MouseHookProc,
        NULL, 0);
    if (mousehook == NULL) printf("Mousehook error %u\n",GetLastError());

    while(true) {
        MSG msg;
        if (GetMessage(&msg,0,0,0)) {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
    }
    UnhookWindowsHookEx(mousehook);

    printf("Procedure completed without exceptional events.\n");

} catch (...) {
    printf("Exception!\n");
}

Upvotes: 1

Views: 288

Answers (2)

Kevin
Kevin

Reputation: 25269

Pthreads don't exist on windows, unless you're using something like cygwin. Either way, the API docs say SetWindowsHookEx associates hooks for application events tied to a particular thread, OR to the desktop on which your app is running. So it can handle being called in a thread, but you need to read the docs so that you call it in a way that gives you the ehavior you want.

Upvotes: 0

Ben Voigt
Ben Voigt

Reputation: 283634

That should be fine.

You may run into trouble if you try to pass pthread thread ids to Windows threading functions which want a thread HANDLE, but here you just need the loop to stay in the same thread as SetWindowsHookEx.

Upvotes: 2

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