Re: Re-creating free threaded objects in the face of multiple threads

"Igor Tandetnik" <>
Mon, 12 Mar 2007 19:16:41 -0400
Dilip <> wrote:

I have a class that encapsulates calls to a free-threaded COM object.
Many worker threads create instances of this class on-the-fly and make
method calls on the COM object. In short:

class COMWrapper
static IOne* pOne_;

   void CreateIOne(); // always called by only one thread at start-up
   void CallCOMWrapperMethod()
   HRESULT hr = pOne_->CallThisMethod();
       if (FAILED(hr))
       // how do I recreate IOne here on just one thread and let all
other worker threads slide by?

If the call fails, I want to release pOne_ and create it again.

The problem is the worker threads -- all of them execute something


so they are all merrily banging away at pOne_->CallThisMethod().
**If** by any chance, the call fails for some reason, it will fail for
all worker threads. I am a little confused how to recreate IOne* in
failure scenario in the presence of all waiting threads.

Try something like this:

 void CallCOMWrapperMethod()
    for (;;) {
        IOne* pCopy = pOne_;
        HRESULT hr = pCopy->CallThisMethod();
        if (SUCCEEDED(hr)) break;

        // We may need to recreate the object
        if (pCopy == pOne_) {
        } // otherwise, somebody else beat us to it.

With best wishes,
    Igor Tandetnik

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