Re: [boost] pool allocation

Subject: Re: [boost] pool allocation
From: Emil Dotchevski (emildotchevski_at_[hidden])
Date: 2009-09-22 21:17:47

Have you considered/evaluated dlmalloc?

Emil Dotchevski
Reverge Studios, Inc.
http://www.revergestudios.com/reblog/index.php?n=ReCode

On Wed, Sep 23, 2009 at 6:55 PM, Stefan Strasser <strasser_at_[hidden]> wrote:
>
> I took a closer look at Boost.Pool today to replace some default allocation of
> small objects.
>
> what I found there was a little disappointing, at least for my use case.
>
> the object_pool has 2 major downsides:
>  - no dynamic block allocation
>  - destroying one(!) object is O(N), with N being the number of unused objects
> in the pool
>
> so I wrote some code for my own use. I'm not suggesting this code should be
> added to boost, but something like it.
>
> struct A{
> ...
> };
>
> {
>  pool<A,100> pool;
>  A *a;
>  for(int c=0;c<250;++c){
>    a=pool.new_(); // O(1)
>  }
>  pool.delete_(a); //O(1), destructs
> } //destruction of 249 objects, O(N)
>
> this allocates 3 memory blocks.
> but it also has one pointer memory overhead per object, to achieve constant
> time deletion.
> but you can use that pointer while the object is in use, which was what lead
> to this code: I needed to store unused boost.intrusive nodes:
>
> struct A : intrusive::[s]list_base_hook<>{
> ...
> };
>
> {
>  [s]list_pool<A,[s]list_base_hook<>,100> pool;
>  //same as above
> }
>
> this has no memory overhead, as the list hook can be used by the pool.
>
> here's the code:
> http://www.boostpro.com/vault/index.php?action=downloadfile&filename=intrusive_pool.hpp&directory=Memory&
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