[webkit-dev] WebKit memory management?

Alexey Proskuryakov ap at webkit.org
Wed Jun 4 01:20:05 PDT 2008

On Jun 4, 2008, at 9:58 AM, Paul Pedriana wrote:

> Thanks for the response. I'm sorry, and perhaps I misunderstand, but  
> I believe your statement about inline operator new is incorrect.  
> Unless I misunderstand you, what you say is not supported by any  
> existing compiler nor is it supported by the C++ language standard.  
> In summary, the 'inline' keyword does not negate or obviate the One  
> Definition Rule. You can demonstrate the problem with the code  
> below. Feel free to correct any misunderstanding that I may have of  
> your explanation.

You are right that the presence of a declaration or inlining do not  
affect the behavior of overridden global operator new, other than via  
possible implementation-specific quirks (because compilers are not  
required to detect ODF violations).

However, I am not aware of any platforms where an overridden operator  
new would have effect across a DLL boundary (note that the C++  
standard doesn't talk about dynamic linking at all). So, this is only  
an issue if you link WebCore to your application statically, or  
specifically export operator new from your DLL. There is no need to do  
the latter, and the former sounds like a violation of LGPL to me. If  
your platform does not support dynamic linking, or you cannot use it  
for some other reason, you may want to investigate the legal  
feasibility of using LGPL-licensed code in your projects before  
pursuing technical solutions.

> Thus you could use WC_NEW("WebCore/page") to flag the memory
> as belonging to that subsystem. This is invaluable in identifying
> memory, producing subsystem metrics, optimizing memory coherence, and
> deducing memory leaks (though other means also help find leaks).

So far, we've been quite happy using platform tools for memory  
debugging. Personally, I do not think that explicitly tagging memory  
in this way would be cost-effective, although this is certainly not  
out of the question.

- WBR, Alexey Proskuryakov

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