Re: [Stlport-devel] Allow cheaper small hash tables

[Herbert D. <Herbert.Duerr@Sun.COM>]

Thanks for applying the patch.

Though hashtables were designed to be most efficient for a couple of 
thousand entries they are good enough for small collections. Not having 
to switch the container type when the container grows is worth a lot.

In many situations the final size of the container is not known until 
much later, but the initial costs are a concern. Along these lines I'm 
considering a change to the hashtable implementation, so that an empty 
hashtable can be as cheap as the other collections like vector/list/set, 
etc. So far I'm confident that from a performance perspective the change 
would only cost one conditional branch which can be predicted almost 
100% correctly, so that the branch is as good as free on all recent 
processors.

On the other hand since for binary compatibility reasons OpenOffice.org 
is married with stlport v4.0 and v4.5 (depending on the platform) I'm 
not sure yet if modifying and testing 4.0, 4.5 and HEAD are worth it if 
we are the only customers of an optimzation for empty hash tables.

-- 
Herbert Duerr