"Getinterfacefromglobal" method returning error code "0x8000ffff" ATL COM( win32, VC++) STA project

Rajesh_M 1

ve implimented a ATL single thread apartment based project .

class ATL_NO_VTABLE CMySrv :
public CComObjectRootEx<ccomsinglethreadmodel>,
public CComCoClass<cmysrv,&clsid_mysrv>,
public IMySrv

In the method, I'm creating multiple worker threads and accessing the interface pointer from one context to another with using COM Interface "IGlobalInterfaceTable"

In the main thread registered the interface

void CMySrv::save()
{
HRESULT hr = 0;
/////
logic
//////
CComQIPtr<imysrv> pMySrv(GetUnknown());
CComPtr<iglobalinterfacetable> l_git;
l_git.CoCreateInstance( CLSID_StdGlobalInterfaceTable );
hr = l_git->RegisterInterfaceInGlobal(pMySrv, __uuidof(IMySrv), &dwCookie );

if(FAILED(hr))
{
//problem with REGISTER Interface....
}

for(int i=0;i<9;i++)
_beginthreadex( 0,0,&(CParllelThreadOperations::ThreadFunc),LPVOID(&dwCookie), 0, &dwThId);

////logic implemented to wait for all the child threads

if (dwCookie != 0)
{
hr =l_git->RevokeInterfaceFromGlobal(dwCookie );
if(FAILED(hr))
{
//problem with revoke Interface....
}
}

}

In the worker thread I'm passing the cookie information and would get the interface

CComPtr<iglobalinterfacetable> git;
CComPtr<imysrv> pMySrv;
HRESULT hr= 0;
if(git.CoCreateInstance( CLSID_StdGlobalInterfaceTable)>=0)
hr= git->GetInterfaceFromGlobal( dwCookie, __uuidof(IMySrv), (void**)&pMySrv);

Most time of the time the implemented code is working fine . But very few times "GetInterfaceFromGlobal" api failed and returning "0x8000ffff" error code for 8 out of 9 worker threads.

Could you please let me know what causes the "GetInterfaceFromGlobal" api to generate "0x8000ffff" error code ,
how can I avoid this scenario.

Note: I can't share the code as it's confidentiality.

Rita Han - MSFT 2,161 Reputation points

2020-11-09T09:03:50.143+00:00
To narrow down this issue, there are two suggestions you can refer to:

It seems you call GetInterfaceFromGlobal in multiple threads. Could you check if one thread reproduces this issue?

Try to debug to see if you can find which function inside of GetInterfaceFromGlobal causes this error.
RLWA32 44,926 Reputation points

2020-11-09T09:48:53.387+00:00

How does your code ensure that the registration of the interface in the GIT is not revoked in one thread while other threads are still calling GetInterfaceFromGlobal?
RLWA32 44,926 Reputation points

2020-11-09T10:56:58.247+00:00

Could you please let me know what causes the "GetInterfaceFromGlobal" api to generate "0x8000ffff" error code , how can I avoid this scenario.

As far as I know there is no single reason that will cause GetInterfaceFromGlobal to return E_UNEXPECTED.

We don't need to see your confidential code.

It would be helpful if you could share a minimal sample that reproduces the problem. Otherwise its just a guessing game.
Rajesh_M 1 Reputation point

2020-11-09T12:59:51.287+00:00

I have used CCOMCriticalsectoin to synchronize the child threads while calling "GetInterfaceFromGlobal",

I'm checking the api return value,

hr= git->GetInterfaceFromGlobal( dwCookie, __uuidof(IMySrv), (void**)&pMySrv);

if(FAILED(hr))
{
//interface revoked failed..
return 0;
}
RLWA32 44,926 Reputation points

2020-11-09T13:27:06.99+00:00

None of the above explains where, when and how the interface is removed from the GIT.

And you never answered the question I asked you in the MSDN forums (original post of question) about whether you have registered proxy/stub for the interface.
Rajesh_M 1 Reputation point

2020-11-09T15:22:39.017+00:00
1 . I'm re moving the interface from GIT at the end of the Save method(which is in the main thread)

I've registered the proxy/stub dll, The implemented logic working most of the times, very few times i'm getting 0x8000ffff error.
RLWA32 44,926 Reputation points

2020-11-09T15:29:44.84+00:00

How do you wait for all the threads other than the main thread to exit before calling RevokeInterfaceFromGlobal?
RLWA32 44,926 Reputation points

2020-11-16T13:37:05.85+00:00

I don't know if you have solved your problem or not but an alternative (available on Win8.1, Win10) to using the GIT would be an agile reference. See nf-combaseapi-rogetagilereference

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"Getinterfacefromglobal" method returning error code "0x8000ffff" ATL COM( win32, VC++) STA project

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