Synchronizing SINGLE-threaded Windows apps?

Tech-Archive recommends: Repair Windows Errors & Optimize Windows Performance

From: Christoph Nahr (christoph.nahr_at_kynosarges.de)
Date: 04/15/04

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    Date: Fri, 16 Apr 2004 00:07:07 +0200

    Multi-threaded applications are well-supported by the .NET Framework.
    Surprisingly, it's much harder to handle single-threaded applications!

    I'm talking about the really nasty Windows habit of checking the
    message queue of the GUI thread at the most inopportune moments, i.e.
    whenever some seemingly innocuous method that relies on Win32 calls is
    executing. If the user happens to press a hotkey or click on some
    window icon (like "X") at this point, Windows makes a forced
    subroutine call to the handler for that event. Meanwhile, the
    previously executing application method is put on ice, as if it had
    called that new handler as a subroutine.

    I understand that this quasi-multitasking is the heritage of 16-bit
    Windows where there were no multiple threads. Well, it's really
    annoying today because it can cause synchronization problem when one
    message handler puts the application in a certain state that renders
    it unable to respond to certain other message handlers... and then,
    sure enough, those other handlers get triggered by user action while
    the first handler is still executing!

    That's really nasty because the usual thread synchronization methods
    don't work -- everything's executing on the same thread, so attempts
    to check a lock either fall through or block eternally.

    So far the only "solution" (more of a hack really) I've found is to
    simply return from the most recent message handler when I've found the
    application state inadequate, and perhaps manually save callback
    instructions for the handler that was already executing.

    Is there some kind of elegant solution for this problem? Any MSDN
    articles discussing this issue? 

    -- 
http://www.kynosarges.de
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