Re: Re-creating free threaded objects in the face of multiple threads
Dilip <rdilipk@lycos.com> 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_;
public:
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
like:
COMWrapper().CallCOMWrapperMethod();
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
Lock();
if (pCopy == pOne_) {
ReleaseIOne();
CreateIOne();
} // otherwise, somebody else beat us to it.
Unlock();
}
}
--
With best wishes,
Igor Tandetnik
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