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From: Jeff Garzik <jgarzik@pobox.com>
To: Git Mailing List <git@vger.kernel.org>,
	Linus Torvalds <torvalds@osdl.org>
Subject: Re: Hash collision count
Date: Sat, 23 Apr 2005 16:33:19 -0400	[thread overview]
Message-ID: <426AB10F.9050300@pobox.com> (raw)
In-Reply-To: <426AAFC3.800@pobox.com>

Jeff Garzik wrote:
> 
> Ideally a hash + collision-count pair would make the best key, rather 
> than just hash alone.
> 
> A collision -will- occur eventually, and it is trivial to avoid this 
> problem:
> 
>     $n = 0
>     attempt to store as $hash-$n
>     if $hash-$n exists (unlikely)
>         $n++
>         goto restart
>     key = $hash-$n


This of course presumes that you know that your new data does not exist 
in the cache.

Otherwise, you would need to hash the on-disk $hash-0 to determine if 
its a collision or a reference.

	Jeff



  reply	other threads:[~2005-04-23 20:28 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-04-23 20:27 Hash collision count Jeff Garzik
2005-04-23 20:33 ` Jeff Garzik [this message]
2005-04-23 23:00 ` Ray Heasman
2005-04-23 23:20   ` Jeff Garzik
2005-04-23 23:46     ` Petr Baudis
2005-04-24  0:35       ` Jeff Garzik
2005-04-24  0:40         ` Petr Baudis
2005-04-24  0:43           ` Jeff Garzik
2005-04-24 21:24             ` Imre Simon
2005-04-24 22:25               ` Whales falling on houses - was: " Jon Seymour
2005-04-25 23:50       ` Tom Lord
2005-04-26  0:00         ` Petr Baudis
2005-04-24  1:01     ` Ray Heasman
2005-04-24  7:56 ` David Lang
  -- strict thread matches above, loose matches on Subject: below --
2005-04-24 23:16 linux

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