Re: [PATCH 02/11] libports: use a single hash table

[Justus Winter]

Quoting Samuel Thibault (2014-05-13 01:00:30)
> Justus Winter, le Mon 12 May 2014 12:05:40 +0200, a écrit :
> > Previously, libports used a hash table per port bucket.  This makes
> > looking up a port difficult if one does not know the port bucket, as
> > one has to iterate over all buckets and do a hash table lookup each.
> 
> But conversely, this makes having to iterate over all ports while one
> may want to just iterate over one bucket.  I'd rather not drop that
> feature.

This feature is not lost.  ports_bucket_iterate (b, ..) iterates over
all ports in bucket b as before.

Also, looking up a port is often done.  Iterating over the ports is
done much less often.  It seems to me that optimizing the former is
more important.

> _ports_bucket_class_iterate is clearly bogus ATM, so we at least need
> something.  Would it be too costly to maintain both a global and a
> per-bucket hash table?  It would at the very worse be only twice as
> expensive as only the global hash table, while still allowing the
> performance gain of iterating over only one bucket.

Having more than one hash table is totally pointless imho.  Since the
port namespace is per-process, and libports is "per-process", having a
hash table per bucket means that all per-bucket hash tables are
disjoint.

Justus