Re: Simplify and speed up uniquify (issue 583390043 by address@hidden)

[dak]

On 2020/01/24 15:50:22, Dan Eble wrote:
> On 2020/01/24 15:17:02, dak wrote:
> > On 2020/01/24 14:11:59, Dan Eble wrote:
> > > On 2020/01/24 14:06:22, hanwenn wrote:
> > > > If the allocation cost becomes problematic, we can use another
hashmap
> > > instead.
> > > 
> > > "We" could profile it and know before pushing whether it is worth
it.
> > 
> > I don't think that this is really performance-critical.
> 
> I accept your informed intuition, but I also have more suggestions.
> 
> Don't assume the hash function is perfect: create the table with more
buckets,
> say 2*size.

I'd not do that.  It's second-guessing the implementation.  The size
should be good as a hint.  In particular if there are actual
duplicates...

> Instead of calling find() then insert(), just call insert() and check
whether it
> worked, something like this (untested):
> 
>     if (seen.insert(grobs[i]).second)
>       grobs[j++] = grobs[i];

Ok, that's a good idea.
 
> https://en.cppreference.com/w/cpp/container/unordered_set/insert



https://codereview.appspot.com/583390043/