Re: [Stlport-devel] Tweaking vector allocation

[Nigel S. <nst...@nv...>]

> 	There is no "swap" of allocator state when the
> 	content of the internal vector and slist is swapped over.
>   
>    I don't understand what the problem is. If you are using an 
> allocator implementation that has a state then all copy of the same 
> original allocator instance should share the same state. See 
> test/unit/stack_allocator.h, this is an example of allocator 
> implementation with a state represented by the State struct. 

François,

I was hoping to avoid having centralised allocation state.
In part this is due to a desire for multi-threading support.
But there are quite a few allocators involved in std::hash_map
with the internal vector and slist, including temporary ones.
Having allocators that are costly to copy or swap don't seem
so promising.  Nor any assumption that the same allocator
is responsible for allocating and deallocating a node.

My main aim is to deal with list, set and map nodes by
allocating larger pieces of memory and subdividing those
to reduce malloc/free traffic and overhead.

I guess this kind of optimisation is not new, but I don't
see too much online regarding custom allocators for
std::hash_map, std::list and std::map.

Thanks again for your suggestions.

Regards,

- Nigel
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