CoMarshalInterThreadInterfaceInStream使用

 

You have to marshal the IServiceProvider interface from your main thread to your background thread.

 

In your SetSite call (which is guaranteed to be called on the main UI thread), marshal the IServiceProvider interface into a shared stream (IStream) object using CoMarshalInterThreadInterfaceInStream. You’ll need to make sure that this shared object can be accessed from both threads. In your background thread, when you need to get at the IServiceProvider, call CoGetInterfaceAndReleaseStream to get back a proxied IServiceProvider that works for the calling thread. Note that you can call this only once, so cache the interface that you get back. You can then call through this interface to QueryService. See the example code below:

 

class CMyPackage : public IVsPacakge

{

private:

 CComPtr< IStream > m_pSPStream; // Used to marshal IServiceProvider between threads

 CComPtr< IServiceProvider > m_pBackgroundSP; // IServiceProvider proxy for the background thread

 

public:

 HRESULT SetSite( IServiceProvider* pSP )

 {

    // Marshal the service provider into a stream so that

    // the background thread can retrieve it later

    CoMarshalInterThreadInterfaceInStream(IID_IServiceProvider, pSP, &m_pSPStream);

 

    //... do the rest of your initialization

 }

 

 // Call this when your background thread needs to call QueryService

 // The first time through, it unmarshals the interface stored

 HRESULT QueryServiceFromBackgroundThread(

    REFGUID rsid,     // [in] Service ID

    REFIID riid,      // [in] Interface ID

    void **ppvObj     // [out] Interface pointer of requested service (NULL on error)

 {

    if( !m_pBackgroundSP )

    {

      if( !m_pSPStream )

      {

        return E_UNEXPECTED;

      }

 

      HRESULT hr = CoGetInterfaceAndReleaseStream( m_pSPStream, IID_IServiceProvider, (void **)&m_pBackgroundSP );

      if( FAILED(hr) )

      {

        return hr;

      }

 

      // The CoGetInterfaceAndReleaseStream has already destroyed the stream.

      // To avoid double-freeing, the smart wrapper needs to be detached.

      m_pSPStream.Detach();

    }

 

    return m_pBackgroundSP->QueryService( rsid, riid, ppvObj );

 }

};