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Re: [RFC/PATCHv2 6/6] limit "contains" traversals based on commit generation

From
Junio C Hamano <gitster@pobox.com>
Date
Jul 13, 2011, 21:12 UTC
Message-ID
<7vpqld6g14.fsf@alter.siamese.dyndns.org>
In-Reply-To
<20110713205844.GA15435@sigill.intra.peff.net>
Jeff King <peff@peff.net> writes:
> Or are you suggesting dropping generations entirely, and just using
> marked-up commit timestamps (or even a flag saying "this timestamp is
> bogus, don't use it for cutoffs")?

Not suggesting, but that was exactly what I was wondering. For example, still_interesting() in revision.c says "compare timestamp and return SLOP, not 'we are done'", and presumably that code could notice that "ah, this commit is marked as being on a stretch that timestamp based cut-off is unusable--keep digging". The "tag --contains" and "name-rev" would also have similar logic (I haven't looked at them for a while though).

> But there's a big question of deciding which timestamps are bogus.

I agree that the ones that you need to dig through may not be the ones with bogus timestamps, but either an ancestor or a descendant (I haven't thought it through) of a commit with bogus timestamp. That is why I said "a commit on a stretch that timestamp based cut-off is unusable".

> But I think I still like generation numbers because:
>
>   1. They're simple, complete, and unambiguous.
No question nor dispute about it.
> The only slowness for the generation slowness is the
> extra I/O on writing out the cache. But it's not very much,...
Ok.
Previous: Jeff KingNext: Jeff King
Message 49 of 57 in “[RFC/PATCHv2 0/6] generation numbers for faster traversals”
  1. Jeff KingJul 13, 2011
  2. 1/6 decorate: allow storing values instead of pointersJeff King, Jul 13, 2011
  3. Jonathan NiederJul 13, 2011
  4. Jeff KingJul 13, 2011
  5. Jeff KingJul 14, 2011
  6. 1/3 implement generic key/value mapJeff King, Jul 14, 2011
  7. Bert WesargJul 14, 2011
  8. Bert WesargJul 14, 2011
  9. Jeff KingJul 14, 2011
  10. Bert WesargJul 14, 2011
  11. Jeff KingJul 14, 2011
  12. Bert WesargJul 14, 2011
  13. 2/3 fast-export: use object to uint32 map instead of "decorate"Jeff King, Jul 14, 2011
  14. Sverre RabbelierJul 15, 2011
  15. Jeff KingJul 15, 2011
  16. 3/3 decorate: use "map" for the underlying implementationJeff King, Jul 14, 2011
  17. Junio C HamanoJul 14, 2011
  18. 0/5 macro-based key/value mapsJeff King, Aug 4, 2011
  19. 1/5 implement generic key/value mapJeff King, Aug 4, 2011
  20. 2/5 fast-export: use object to uint32 map instead of "decorate"Jeff King, Aug 4, 2011
  21. 3/5 decorate: use "map" for the underlying implementationJeff King, Aug 4, 2011
  22. 4/5 map: implement persistent mapsJeff King, Aug 4, 2011
  23. 5/5 implement metadata cache subsystemJeff King, Aug 4, 2011
  24. 0/2 patch-id cachingJeff King, Aug 4, 2011
  25. 1/2 cherry: read default configJeff King, Aug 4, 2011
  26. 2/2 cache patch ids on diskJeff King, Aug 4, 2011
  27. Jeff KingAug 4, 2011
  28. Jeff KingAug 5, 2011
  29. René ScharfeAug 5, 2011
  30. Jeff KingAug 6, 2011
  31. 2/6 add metadata-cache infrastructureJeff King, Jul 13, 2011
  32. Bert WesargJul 13, 2011
  33. Jeff KingJul 13, 2011
  34. Bert WesargJul 13, 2011
  35. Jeff KingJul 13, 2011
  36. Junio C HamanoJul 13, 2011
  37. Junio C HamanoJul 13, 2011
  38. Jeff KingJul 13, 2011
  39. 3/6 commit: add commit_generation functionJeff King, Jul 13, 2011
  40. Eric SunshineJul 13, 2011
  41. 4/6 pretty: support %G to show the generation number of a commitJeff King, Jul 13, 2011
  42. 5/6 check commit generation cache validity against graftsJeff King, Jul 13, 2011
  43. Eric SunshineJul 13, 2011
  44. Jeff KingJul 13, 2011
  45. 6/6 limit "contains" traversals based on commit generationJeff King, Jul 13, 2011
  46. Jeff KingJul 13, 2011
  47. Junio C HamanoJul 13, 2011
  48. Jeff KingJul 13, 2011
  49. Junio C HamanoJul 13, 2011
  50. Jeff KingJul 13, 2011
  51. Junio C HamanoJul 15, 2011
  52. Jeff KingJul 15, 2011
  53. Junio C HamanoJul 15, 2011
  54. Jeff KingJul 15, 2011
  55. Generation numbers and replacement objectsJakub Narebski, Jul 15, 2011
  56. Jeff KingJul 15, 2011
  57. Jakub NarebskiJul 16, 2011

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