Re: Firing an event from a worker thread

From:
"Chris" <chris@scadaengine.com>
Newsgroups:
microsoft.public.vc.atl
Date:
2 Aug 2006 14:12:39 -0700
Message-ID:
<1154553159.036232.136940@75g2000cwc.googlegroups.com>
Hello Alexander,

The thread is created by the COM object as follows. I don't use Windows
messages inside the Main Thread, the messaging is done via a FIFO stack
using a push/pop mechanism. The messages originate from another thread
that has a longer lifecycle. I use the CComDynamicUnkArray_GIT template
class that was published on the web. Any thoughts would be very much
appreciated.

/*-----------------------------------------------------------------------------
 *
 * content: The last called function in initilizing com object.
 *
 * input: none
 *
 * return: none
 */
HRESULT
CApplicationLayer::FinalConstruct()
{
    THREAD_ID threadID;

    pAppLayer = this;
    Thread_Sem_Init(&thread.semaphore);

    // create the thread
    thread.m_hThread = CreateThread(
                            NULL,
                            0,
                            &ThreadProc,
                            reinterpret_cast< void* >(this),
                            0,
                            (unsigned long*)&threadID);

    //Wait for the thread to signal that it has started
    Thread_Sem_Wait(&thread.semaphore);

    return S_OK;
}

/*-----------------------------------------------------------------------------
 *
 * content: The last called function before com object wil be
destroyed.
 *
 * input: none
 *
 * return: none
 */
void CApplicationLayer::FinalRelease()
{
    DestroyThread();
}

// the thread function
DWORD WINAPI
CApplicationLayer::ThreadProc(LPVOID lpParameter)
{
    pApplicationLayer = reinterpret_cast< CApplicationLayer*

(lpParameter);


    CoInitializeEx(NULL, COINIT_MULTITHREADED);

    do
    {
        if (!pApplicationLayer->OnInitInstance())
            break;

        if (!pApplicationLayer->Run())
            break;

    } while (True);

    pApplicationLayer->OnExitInstance();
    CoUninitialize();

    return 0;
}

void CApplicationLayer::DestroyThread()
{
    thread.keep_going = FALSE;
    //Wait for it to stop
    Thread_Sem_Wait(&thread.semaphore);
    Thread_Sem_Destroy(&thread.semaphore);
    THREAD_CLOSE_HANDLE(thread.m_hThread);
}

//The Event being fired would look like this :-

    HRESULT Fire_Iam(BACnetServiceIam *service)
    {
        HRESULT hr;
        CComVariant varResult;
        CComObject<CIam> *Iam;
        VARIANT vntArg;

        T* pT = static_cast<T*>(this);
        int nConnectionIndex;
        int nConnections = m_vec.GetSize();

        for (nConnectionIndex = 0; nConnectionIndex < nConnections;
nConnectionIndex++)
        {
            pT->Lock();
            CComPtr<IUnknown> sp = m_vec.GetAt(nConnectionIndex);
            pT->Unlock();
            CComQIPtr< IDispatch, &IID_IDispatch > pDispatch( sp.p );
            if (pDispatch.p != NULL)
            {
                VariantClear(&varResult);
                //Create a new Iam object
                if (hr = CComObject<CIam>::CreateInstance(&Iam))
                    return hr;
                //Set the pointers up
                Iam->Iam.iAmDeviceIdentifier = service->iAmDeviceIdentifier;
                Iam->Iam.maxAPDULengthAccepted = service->maxAPDULengthAccepted;
                Iam->Iam.segmentationSupported = service->segmentationSupported;
                Iam->Iam.vendorID = service->vendorID;

                ::VariantInit(&vntArg);
                V_VT(&vntArg) = VT_DISPATCH;
                Iam->GetUnknown()->QueryInterface(IID_IIam,
(void**)&vntArg.pdispVal);

                DISPPARAMS disp = { &vntArg, NULL, 1, 0 };
                pDispatch->Invoke(0x1, IID_NULL, LOCALE_USER_DEFAULT,
DISPATCH_METHOD, &disp, &varResult, NULL, NULL);
                Iam->GetUnknown()->Release();
            }
        }
        return varResult.scode;

    }

Alexander Nickolov wrote:

Who is responsible for the lifetime of your thread? Is it a
COM object?

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