Question

Note:

• Using raw Win32 CreateTheard() API
• No MFC
• An interface is simply a pointer to a vtable

Question:

• How to pass an interface pointer to a thread?

Illustration:

IS8Simulation *pis8 = NULL;  ...  CoCreateInstance(                  clsid,                  NULL,                  CLSCTX_LOCAL_SERVER,                  __uuidof(IS8Simulation),                  (void **) &pis8);    ...  hThread = CreateThread(                 NULL,                 0,                 SecondaryThread,                 //interface pointer pis8                 0,                 &dwGenericThreadID);  ...  DWORD WINAPI SecondaryThread(LPVOID iValue) {     //using iValue accordingly     //E.g.: iValue->Open 

Regards

Answer 1

As was stated below, passing a COM interface pointer between threads in not safe.

Assuming you know what you are doing:

hThread = CreateThread(                 NULL,                         0,                         SecondaryThread,                         (LPVOID) pis8                         0,                         &dwGenericThreadID);  DWORD WINAPI SecondaryThread(LPVOID iValue) {    ((IS8Simulation*) iValue)->Open(); } 

Thread safe version:

void MainThread() {     IStream* psis8;     HRESULT res = CoMarshalInterThreadInterfaceInStream (IID_IS8SIMULATION, pis8, &psis8);     if (FAILED(res))          return;     hThread = CreateThread(                 NULL,                 0,                 SecondaryThread,                 (LPVOID) psis8                 0,                 &dwGenericThreadID           ); }  DWORD WINAPI SecondaryThread(LPVOID iValue) {    IS8Simulation* pis8;    HRESULT res = CoGetInterfaceAndReleaseStream((IStream*) iValue, IID_IS8SIMULATION, &pis8);    if (FAILED(res))       return (DWORD) res;    pis8->Open(); }