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Re: A look at some alternative PACK file encodings

From
Jon Smirl <jonsmirl@gmail.com>
Date
Sep 7, 2006, 00:59 UTC
Message-ID
<9e4733910609061759m2aae9e31ja146e309dc449628@mail.gmail.com>
In-Reply-To
<Pine.LNX.4.64.0609062037560.18635@xanadu.home>
On 9/6/06, Nicolas Pitre <nico@cam.org> wrote:
Show 10 quoted lines
> On Wed, 6 Sep 2006, Jon Smirl wrote:
>
> > Shawn is doing some prototype work on true dictionary based
> > compression. I don't know how far along he is but it has potential for
> > taking 30% off the Mozilla pack.
>
> BTW I'm half-way done with support for deltas which base object is
> referenced with an offset in the pack instead of a hash.  It is quite
> messy though since it touches pretty core code all over the place when
> it comes to fetching objects out of a pack.

Would it help to change all of the references in the pack from sha1 to encoded relative offsets? Then collect all of the object fetch code into a single subroutine which would change it algorithm depending on which type of pack it is operating on. Now the pack wouldn't mix reference types, they would all be encoded relative or sha1.

-- 
Jon Smirl
jonsmirl@gmail.com
Previous: Nicolas PitreNext: Nicolas Pitre
Message 14 of 24 in “A look at some alternative PACK file encodings”
  1. A Large Angry SCMSep 6, 2006
  2. Jon SmirlSep 6, 2006
  3. A Large Angry SCMSep 6, 2006
  4. Linus TorvaldsSep 6, 2006
  5. Jon SmirlSep 7, 2006
  6. David LangSep 7, 2006
  7. A Large Angry SCMSep 7, 2006
  8. Linus TorvaldsSep 7, 2006
  9. Nicolas PitreSep 7, 2006
  10. Jon SmirlSep 7, 2006
  11. Shawn PearceSep 7, 2006
  12. Shawn PearceSep 7, 2006
  13. Nicolas PitreSep 7, 2006
  14. Jon SmirlSep 7, 2006
  15. Nicolas PitreSep 7, 2006
  16. A Large Angry SCMSep 7, 2006
  17. Junio C HamanoSep 7, 2006
  18. Nicolas PitreSep 7, 2006
  19. Shawn PearceSep 7, 2006
  20. Junio C HamanoSep 7, 2006
  21. Shawn PearceSep 7, 2006
  22. Junio C HamanoSep 7, 2006
  23. Shawn PearceSep 7, 2006
  24. A Large Angry SCMSep 7, 2006

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