[OLE] Better handling of References

[fenix at club-internet.fr]

>On Wed, 26 May 2004 03:55:25 +0200, Raphael wrote:
>>  I'm trying to install Splinter Cell Demo (installshield).
>>  And i have seen:
>>  - one typelib was released while typeinfos (childs of typelib) are in use
>>  - the install "crash" (catched and returns an E_UNEXPECTED error) when it 
>> wants to call ITypeInfo_fnGetContainingTypeLib (who want to AddRef the 
>> freshly released TypeLib)
>
>Hi Raphael, 

Hi Mike

>This has been a known problem for a long time now, with several attempts
>to fix it, all of them have been incorrect. It seems your approach is a
>new one and interesting, but I'm not sure this is how Windows does it.

Well Soft References are used in many places in COM (for example D3D textures/surfaces use it on windows)

>Does anybody know exactly what Windows does in this situation? It might be
>worth writing a test case to find out. 
>
>Objects in a semi-freed state seem like a slightly odd way to do things.
>
>> Now i have another crash later, but it seems a problem with an invoke method 
>> who failed :(
>> If any ole/rpc expert can look at this problem i'll be very happy :)
>
>Well, if you could provide more detail (backtrace etc) on the crash it
>would be good.

I can't have a backtrace as i can't get winedbg working correctly on installshield programs :(
But i'll send you the traces later (when i'll be back home).

For what i have see it's a problem of ITypeInfo::Invoke 
when it should returns a Pointer to an IUnknown Variant.
InstallShield complains about Objects References not set !!

>A few comments on the patch:
>
>-    --(This->ref);
>+    /** escape decrement for soft_references */
>+    if (This->ref > 0) {
>+      --(This->ref);
>+    } else {
>+      ERR("trying to Release again an ITypeLib2 in freing state waiting for ITypeInfo (%p) childs Releases\n", This);
>+    }
>
>I don't remember whether this object is supposed to be thread safe or not,
>but should this not be an InterlockedDecrement?

Yes, but as the code of ITypeLib2/ITypeInfo don't seems thread safe at all ... (anyway i'll fix it) :)

>I think the error could be better phrased as:
>
>ERR("Reference count on an ITypeLib2 object (%p) already zero: waiting for
>ITypeInfo children to be released as well");

:)

>or words to that effect.
>
>+      if (This->soft_ref > 0) {
>+	ERR("trying to Release an ITypeLib2 while some ITypeInfo (%p) childs are actually with Refs > 1. So Dont free it now \n", This);
>+	/** maybe scaning ITypeInfo list to dump ITypeInfos with Refs  > 1 */
>+	return 1;
>+      }
>
>Is it actually an error to do that? If you free a typelib while refs are
>held on child typeinfos, is this a bug in the app or a legitimate thing to
>do? If it's not a bug in the app we probably shouldn't use ERR here.

Weel, we had problems like that on d3d8 (a long time ago) about ref counting. 
For me, seems more a wine bug (we have to found where missing AddRefs as to be done) than an app bug (new traces can help us to find what happened)

>--- variant.c	30 Apr 2004 18:32:58 -0000	1.97
>+++ variant.c	26 May 2004 01:46:44 -0000
>@@ -605,6 +605,8 @@
> 
>   hres = VARIANT_ValidateType(V_VT(pVarg));
> 
>+  if (V_VT(pVarg) == VT_EMPTY) return hres;
>+
>   if (SUCCEEDED(hres))
>   {
>     if (!V_ISBYREF(pVarg))
>
>This change looks OK though I'm not sure why it's necessary. Does the
>Splinter Cell installer actually need this?

No, i have only to no have a lot of debug traces (i have added on my tree) on Variant* Operations when clearing already empty Variants

>thanks -mike
>

Regards,
Raphael