Re: [boost] Performance comparison between ptr_vector and vector<cow_ptr<Shape> >, vector<copy_ptr<Shape> >

From: Thorsten Ottosen (tottosen_at_[hidden])
Date: 2006-01-04 11:48:25

Thorsten Ottosen wrote:
> axter wrote:
> 
>>This is a continuation on a thread discussion advocating replacing the boost
>>pointer containers with cow_ptr as the default pointer containers.
> 
> Test performance for initializing and copying container of pointers.
> 
> vector<copy_ptr<Shape> > 0.42 s
> 
> boost::ptr_vector<Shape> 0.42 s
> 
> vector<cow_ptr<Shape> > 0.09 s
>  >>>>>>>>>>>>>>>>>>
> 
> cow_ptr seems to win here. I can't figure out why cow_ptr is so much 
> faster. ptr_vector uses cloning, of course, whereas cow_ptr does 
> something else.
> 

I further tried to add the proper return type to the functions, such 
that ptr_vector<T> returns by auto_ptr< ptr_vector<T> > and vector<T> as
vector<T>. On top of this, I save the return-value and called size() on it.

This gave:

Test performance for initializing and copying container of pointers.

vector<copy_ptr<Shape> > 1.42 s

boost::ptr_vector<Shape> 0.81 s

vector<cow_ptr<Shape> > 0.13 s

But this test is a bit unfair: we create copies of the vector, but we 
never mutate that copy. A fair test would mutate all the elements.

-Thorsten