RE: [boost] boost::pool feature requests

From: scleary_at_[hidden]
Date: 2002-11-22 13:45:11

> -----Original Message-----
> From: Alberto Barbati [mailto:abarbati_at_[hidden]]
> 
> 1) purge_memory() does not reset the member next_size

Yes, this is in fact a bug, and it will be fixed.

> 2) the name release_memory() confuses me. It makes me think that all 
> memory is being released, a task accomplished by purge_memory(). I think 
> a better name could be release_unused_memory(). This function also 
> should reduce the value of next_size, for example by considering the 
> size of the largest block left in the pool.

The current name will remain, for backwards compatibility.  Does anyone else
want a "release_unused_memory" alias?

And it will also be updated to change next_size in a manner similar to the
way you describe.

> 3) I would like to have a function to free the entire pool _without_ 
> releasing the memory. The rationale for this is in the example above. 
> Most probably, the number of objects allocated in each iteration of my 
> application is almost the same. At the end of an iteration, I would like 
> to free all allocated objects with one single call (as I have thousands 
> of objects, it makes the difference) yet it's a waste of time to free 
> the memory, because I will need the same amount again in the next 
> iteration. Such function could be called free_all_chunks() or 
> something similar.

This should certainly be possible, and sounds reasonable; I'll look into it.

> 4) what's the use of ordered_alloc/ordered_free? I made a few tests and 
> they are indeed a bit slower than regular alloc/free, without any 
> apparent advantage. Am I missing something?

Keeping the free list ordered allows algorithms that traverse the free list
along with the memory owned by pool to work correctly/more efficiently:
  1) array allocations will be more efficient (pool_allocator keeps its free
list ordered, whereas fast_pool_allocator does not)
  2) release_memory() will work correctly
  3) object_pool uses the ordered property to efficiently implement the
automatic destructor calls for allocated objects

        -Steve