[Qt-interest] Replace Qt Allocator

[RZ]

Hi,

don't know if that helps - but we use TLSF (which is not so much faster 
AFAIK but maybe we have slightly different use cases).

We also had problems with "strange" crashes - until a colleague found 
out that we had to use a compiler switch (for thread enabling within TLSF).

hmm, maybe there's something like this....

RZ

> Hello All,
> 
>  
> 
> Our program uses a system allocator called nedmalloc. We override the 
> new and delete operators to use this system allocator. However, after 
> porting to Qt 4 we have ran into some issues with the QList class and 
> it’s destructor. When the list is destructed, it attempts to free the 
> memory created by the list, but nedfree() crashes because the memory was 
> instantiated using the system allocator, malloc(). Here is the problem:
> 
>  
> 
> The problem is indeed a violation of the ODR requirement in the ISO C++ 
> spec. For example in this line:
> 
>  
> 
>    QModelIndexList indexes = list->selectionModel()->selectedRows();
> 
>  
> 
> QModelIndexList exists in the local binary due to being a templated type 
> based on QList, therefore its destructor is called from the local binary 
> where ::operator delete has been defined to invoke nedmalloc. 
> Unfortunately the initial constructor of the list (selectedRows()) 
> exists in one of the Qt DLL binaries where ::operator new is defined to 
> invoke the system allocator.. Therefore the list is being constructed 
> with the system allocator and destructed with nedmalloc - this obviously 
> enough provokes a segfault as ODR is violated.
> 
>  
> 
> I was told by some guys on this interest board that I should build 
> nedmalloc into Qt. However, after doing so, I still get the same error. 
> What I did to build nedmalloc into Qt, was I modified the body of 
> qFree(), qMalloc(), and qRealloc() to use nedfree(), nedmalloc(), and 
> nedRealloc() respectively. This apparently was not enough to fix the 
> problem. Could anyone tell me what else needs to be done? Do I need to 
> override the new and delete operators in Qt as well? Are there any 
> direct calls to malloc() in the code that I am unaware of?
> 
>  
> 
> Any help with this would be greatly appreciated!
> 
>  
> 
> Eric
> 
>  
>