Re: [Opensg-users] [OpenSG 2.x] Bug fixes

[Johannes <JBrunen@DataSolid.de>]

Hello Gerrit,

good to here from you :-)

>>>>> 2. OSGShaderCacheTree.inl: The ShaderCacheTreeV3::sub() method is imho
>>>>> incorrect. The ShaderCache::clear() function currently does not work
>>>>> properly. I was facing references to already destroyed ShaderCache
>>>>> objects from ShaderProgramVariableChunks.
>
> for my understanding, what happens is you sub some cache entries and
> later on Cache::clear the system tries to delete them again. Your patch
> looks ok, though I'm still not sure where the subtle difference is ;).
>
> Is it easy to dump a dot file for this case.

No it is not :-( The model with which I have worked on the issue was 
rather big and I did have a complicated procedure list to reproduce the 
error. I was able to find a way to get imho to the cause of the problem 
in function 'void ShaderCacheTreeV3<ObjectT, LevelBits>::sub(UInt32 
uiIdx)' but can't remember the steps which have taken me to this place 
in detail. The problem is the missing '0x0000 != (i & uiCurrBits) &&' 
part in the second 'if' statement. This leads to remaining entries in 
the cache which do pop up later on.

I do have some dot files and logging of instrumented code of the 
original case. But I'm not sure that this information is of any help for 
you.

Attached you find what I do have. The session goes from program start to 
crash. I did have the code somehow instrumented by adding member 
'_oDbg_store' in the ShaderCache. I fill this set in the 
'updateRemoveCallback()' function for each 'addDestroyedFunctor' call. 
The crash happens since this set is not empty in the ShaderCache destructor:

ss << "ShaderCache::dtor = " << std::hex << this << " still in 
_oDbg_store = " << *iter;

For this reason, the living objects carrying the callback 
'ShaderCache::removeShaderVar' due to the 'addDestroyedFunctor' calls, 
might execute the callback in the already destroyed ShaderCache object. 
After inspection of the code I have found that the 'removeShaderVar' 
function do not remove all entries in the '_oVarTree.sub(uiVarId);' call.

I hope I could give you enough information to tackle the issue.

Best,
Johannes