[Python-Dev] Dictionary tuning

[Guido van Rossum]

> What could be much worse is that stuffing code into the if-block
> bloats the code so much as to frustrate lookahead I-stream caching
> of the normal "branch taken and return 0" path:
> 
> 	if (mp->ma_used > n_used && mp->ma_fill*3 >= (mp->ma_mask+1)*2) {
> 		if (dictresize(mp, mp->ma_used*2) != 0)
> 			return -1;
> 	}
> 	return 0;
> 
> Rewriting as
> 
> 	if (mp->ma_used <= n_used || mp->ma_fill*3 < (mp->ma_mask+1)*2)
> 		return 0;
> 
> 	return dictresize(mp, mp->ma_used*2) ? -1 : 0;

That last line might as well be

	return dictresize(mp, mp->ma_used*2); /* Or *4, per Raymond */

Which reminds me, there are two other places where dictresize() is
called; shouldn't those be changed to the new fill factor?

All in ll I think I'm mildly in favor of this change.

--Guido van Rossum (home page: http://www.python.org/~guido/)