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Re: A look at some alternative PACK file encodings

From
Junio C Hamano <junkio@cox.net>
Date
Sep 7, 2006, 01:11 UTC
Message-ID
<7v1wqo5vlz.fsf@assigned-by-dhcp.cox.net>
In-Reply-To
<Pine.LNX.4.64.0609062037560.18635@xanadu.home>
Nicolas Pitre <nico@cam.org> writes:
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.

I wonder how you made unpack-objects to work with it. Do you store an extra bit in the packed stream to say "this object will be used as a delta base for later objects so remember its offset and resulting SHA1", or do you just remember every entry as you unpack?

Previous: A Large Angry SCMNext: Nicolas Pitre
Message 17 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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