linux-kernel - Re: [RFC] B+Tree library V2

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Message-ID: <20090108194638.GC24884@logfs.org>
Date:	Thu, 8 Jan 2009 20:46:38 +0100
From:	Jörn Engel <joern@...fs.org>
To:	Johannes Berg <johannes@...solutions.net>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [RFC] B+Tree library V2

On Thu, 8 January 2009 17:50:04 +0100, Johannes Berg wrote:
> 
> I see this:
> 
> 
> - * Second trick is to special-case the key "0" or NUL.  As seen above, this
> - * value indicates an unused slot, so such a value should not be stored in the
> - * tree itself.  Instead it is stored in the null_ptr field in the btree_head.
> 
> Does that mean that wasn't true, and I can store a 0 key?

Ahh, don't look at that!  The embarrassment is unbearable!  Go away!

Yes, I used to have a special exception for a 0 key.  But I also have
a special exception for a NULL value and can test against that instead
of testing against a 0 key.  It is even faster, because the value is not
variable-sized.  In hindsight it is hard to explain why I ever did that.

Jörn

-- 
Unless something dramatically changes, by 2015 we'll be largely
wondering what all the fuss surrounding Linux was really about.
-- Rob Enderle
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