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Re: remove_duplicates() in builtin/fetch-pack.c is O(N^2)

From
MFMartin Fick <mfick@codeaurora.org>
Date
May 25, 2012, 01:32 UTC
Message-ID
<201205241932.37045.mfick@codeaurora.org>
In-Reply-To
<20120525010434.GA11861@sigill.intra.peff.net>
On Thursday, May 24, 2012 07:04:34 pm Jeff King wrote:
> On Thu, May 24, 2012 at 06:54:56PM -0600, Martin Fick 
wrote:
Show 8 quoted lines
> > > Yes, exclusively warm. And all of the refs were
> We'd have to give some thought to potential race
> conditions, though. Usually pack-refs isn't modifying
> the ref, so it can just write out the value to the
> packed-refs file, then delete the loose ref if nobody
> has touched it since we wrote. But here we're combining
> it with a modification, so I suspect there would be a
> race with another process trying to modify it.

Yeah, I thought about that. Could you just right the new packed-ref file with the new refs and the old refs which were in the file already, then just delete any loose refs which were ones which were just added by this operation, only if they have not changed?

This way, if someone else modifies one of the same refs, they could just win?

-Martin
-- 
Employee of Qualcomm Innovation Center, Inc. which is a 
member of Code Aurora Forum
Previous: Jeff KingNext: Jeff King
Message 28 of 46 in “remove_duplicates() in builtin/fetch-pack.c is O(N^2)”
  1. Michael HaggertyMay 21, 2012
  2. Junio C HamanoMay 21, 2012
  3. demerphqMay 21, 2012
  4. Jeff KingMay 21, 2012
  5. Jeff KingMay 21, 2012
  6. 1/5 fetch-pack: sort incoming headsJeff King, May 21, 2012
  7. Junio C HamanoMay 22, 2012
  8. Jeff KingMay 22, 2012
  9. Jeff KingMay 24, 2012
  10. 2/5 fetch-pack: avoid quadratic behavior in remove_duplicatesJeff King, May 21, 2012
  11. 3/5 add sorting infrastructure for list refsJeff King, May 21, 2012
  12. 4/5 fetch-pack: sort the list of incoming refsJeff King, May 21, 2012
  13. 5/5 fetch-pack: avoid quadratic loop in filter_refsJeff King, May 21, 2012
  14. Junio C HamanoMay 22, 2012
  15. Jeff KingMay 21, 2012
  16. Jeff KingMay 22, 2012
  17. Michael HaggertyMay 22, 2012
  18. Jeff KingMay 22, 2012
  19. Michael HaggertyMay 22, 2012
  20. Jeff KingMay 22, 2012
  21. Michael HaggertyMay 22, 2012
  22. Jeff KingMay 22, 2012
  23. Michael HaggertyMay 24, 2012
  24. Martin FickMay 25, 2012
  25. Jeff KingMay 25, 2012
  26. Martin FickMay 25, 2012
  27. Jeff KingMay 25, 2012
  28. Martin FickMay 25, 2012
  29. Jeff KingMay 25, 2012
  30. Nguyen Thai Ngoc DuyMay 22, 2012
  31. Michael HaggertyMay 22, 2012
  32. Jeff KingMay 22, 2012
  33. Junio C HamanoMay 22, 2012
  34. Jeff KingMay 22, 2012
  35. Michael HaggertyMay 24, 2012
  36. Nguyen Thai Ngoc DuyMay 23, 2012
  37. Junio C HamanoMay 22, 2012
  38. Martin FickMay 21, 2012
  39. Jeff KingMay 21, 2012
  40. Junio C HamanoMay 21, 2012
  41. Jeff KingMay 21, 2012
  42. Martin FickMay 22, 2012
  43. Jeff KingMay 22, 2012
  44. Martin FickMay 22, 2012
  45. Junio C HamanoMay 22, 2012
  46. Martin FickMay 23, 2012

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