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Re: [PATCH/RFC v3 01/13] Move index v2 specific functions to their own file

From
Nguyen Thai Ngoc Duy <pclouds@gmail.com>
Date
Aug 10, 2012, 02:23 UTC
Message-ID
<CACsJy8ChnS4cE3YnQQA8YQ5ebCA06QBXxEB7Oqhv4z_1y9Wc8w@mail.gmail.com>
In-Reply-To
<7v7gt7mwo3.fsf@alter.siamese.dyndns.org>
On Fri, Aug 10, 2012 at 7:13 AM, Junio C Hamano <gitster@pobox.com> wrote:
Show 15 quoted lines
> By the way, you can only detect such inconsistency when you are
> lucky enough that you catch the other person in the middle of
> writing.
>
> If the index you are looking at holds a large tree with very many
> paths, it is possible that there are two large directories, and
> after you read all entries from one, the other process starts
> modifying the paths in that directory, without you ever finding it
> out.  If the goal of the topic is to make the index work better in
> projects with large trees, it may be wise to think about locking the
> whole thing, so that you do not have to rely on the per-entry crc
> and you being lucky to detect such a race.  The per-entry crc, as
> far as I understand, may have been introduced primarily to detect
> on-disk data corruption; it is not a suitable mechanism to detect
> conflicting accesses.

So we acquire the lock just before we need to write, or at the time we open for reading?

-- 
Duy
Previous: Junio C HamanoNext: Thomas Rast
Message 8 of 34 in “Introduce index file format version 5”
  1. 0/13 Introduce index file format version 5Thomas Gummerer, Aug 8, 2012
  2. 01/13 Move index v2 specific functions to their own fileThomas Gummerer, Aug 8, 2012
  3. Nguyen Thai Ngoc DuyAug 8, 2012
  4. Thomas GummererAug 8, 2012
  5. Junio C HamanoAug 9, 2012
  6. Thomas GummererAug 9, 2012
  7. Junio C HamanoAug 10, 2012
  8. Nguyen Thai Ngoc DuyAug 10, 2012
  9. Thomas RastAug 10, 2012
  10. Junio C HamanoAug 10, 2012
  11. Thomas GummererAug 10, 2012
  12. 02/13 t2104: Don't fail for index versions other than [23]Thomas Gummerer, Aug 8, 2012
  13. 03/13 t3700: Avoid interfering with the racy codeThomas Gummerer, Aug 8, 2012
  14. 04/13 Add documentation of the index-v5 file formatThomas Gummerer, Aug 8, 2012
  15. Junio C HamanoAug 9, 2012
  16. Thomas GummererAug 9, 2012
  17. Junio C HamanoAug 9, 2012
  18. 05/13 Make in-memory format aware of stat_crcThomas Gummerer, Aug 8, 2012
  19. 06/13 Read index-v5Thomas Gummerer, Aug 8, 2012
  20. Nguyen Thai Ngoc DuyAug 8, 2012
  21. Johannes SixtAug 8, 2012
  22. Junio C HamanoAug 8, 2012
  23. Thomas GummererAug 8, 2012
  24. 07/13 Read resolve-undo dataThomas Gummerer, Aug 8, 2012
  25. Junio C HamanoAug 9, 2012
  26. Thomas GummererAug 9, 2012
  27. Junio C HamanoAug 10, 2012
  28. Thomas GummererAug 10, 2012
  29. 08/13 Read cache-tree in index-v5Thomas Gummerer, Aug 8, 2012
  30. 09/13 Write index-v5Thomas Gummerer, Aug 8, 2012
  31. 10/13 Write index-v5 cache-tree dataThomas Gummerer, Aug 8, 2012
  32. 11/13 Write resolve-undo data for index-v5Thomas Gummerer, Aug 8, 2012
  33. 12/13 update-index.c: always rewrite the index when index-version is givenThomas Gummerer, Aug 8, 2012
  34. 13/13 p0002-index.sh: add perf test for the index formatsThomas Gummerer, Aug 8, 2012

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