linux-kernel - Re: [PATCH v3 01/17] hashtable: introduce a small and naive hashtable

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Message-ID: <20120824203332.GF21325@google.com>
Date:	Fri, 24 Aug 2012 13:33:32 -0700
From:	Tejun Heo <tj@...nel.org>
To:	Sasha Levin <levinsasha928@...il.com>
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
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Subject: Re: [PATCH v3 01/17] hashtable: introduce a small and naive
 hashtable

Hello, Sasha.

On Fri, Aug 24, 2012 at 10:11:55PM +0200, Sasha Levin wrote:
> > If this implementation is about the common trivial case, why not just
> > have the usual DECLARE/DEFINE_HASHTABLE() combination?
> 
> When we add the dynamic non-resizable support, how would DEFINE_HASHTABLE() look?

Hmmm?  DECLARE/DEFINE are usually for static ones.

> > I don't know.  If we stick to the static (or even !resize dymaic)
> > straight-forward hash - and we need something like that - I don't see
> > what the full encapsulation buys us other than a lot of trivial
> > wrappers.
> 
> Which macros do you consider as trivial within the current API?
> 
> Basically this entire thing could be reduced to DEFINE/DECLARE_HASHTABLE and
> get_bucket(), but it would make the life of anyone who wants a slightly
> different hashtable a hell.

Wouldn't the following be enough to get most of the benefits?

* DECLARE/DEFINE
* hash_head()
* hash_for_each_head()
* hash_add*()
* hash_for_each_possible*()

> I think that right now the only real trivial wrapper is hash_hashed(), and I
> think it's a price worth paying to have a single hashtable API instead of
> fragmenting it when more implementations come along.

I'm not objecting strongly against full encapsulation but having this
many thin wrappers makes me scratch my head.

Thanks.

-- 
tejun
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