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Re: [PATCH v3 15/24] read-cache: read index-v5

From
Thomas Gummerer <t.gummerer@gmail.com>
Date
Aug 20, 2013, 21:13 UTC
Message-ID
<87txik3w2f.fsf@gmail.com>
In-Reply-To
<CACsJy8CNHNj6dScPUCiRnv=zqT9QfY+=v3ECsnUR2uR4nkFQHg@mail.gmail.com>
Duy Nguyen <pclouds@gmail.com> writes:
Show 42 quoted lines
> On Mon, Aug 19, 2013 at 2:42 AM, Thomas Gummerer <t.gummerer@gmail.com> wrote:
>> +static int read_entry(struct cache_entry **ce, char *pathname, size_t pathlen,
>> +                     void *mmap, unsigned long mmap_size,
>> +                     unsigned int first_entry_offset,
>> +                     unsigned int foffsetblock)
>> +{
>> +       int len, offset_to_offset;
>> +       char *name;
>> +       uint32_t foffsetblockcrc, *filecrc, *beginning, *end, entry_offset;
>> +       struct ondisk_cache_entry *disk_ce;
>> +
>> +       beginning = ptr_add(mmap, foffsetblock);
>> +       end = ptr_add(mmap, foffsetblock + 4);
>> +       len = ntoh_l(*end) - ntoh_l(*beginning) - sizeof(struct ondisk_cache_entry) - 5;
>> +       entry_offset = first_entry_offset + ntoh_l(*beginning);
>> +       name = ptr_add(mmap, entry_offset);
>> +       disk_ce = ptr_add(mmap, entry_offset + len + 1);
>> +       *ce = cache_entry_from_ondisk(disk_ce, pathname, name, len, pathlen);
>> +       filecrc = ptr_add(mmap, entry_offset + len + 1 + sizeof(*disk_ce));
>> +       offset_to_offset = htonl(foffsetblock);
>> +       foffsetblockcrc = crc32(0, (Bytef*)&offset_to_offset, 4);
>> +       if (!check_crc32(foffsetblockcrc,
>> +               ptr_add(mmap, entry_offset), len + 1 + sizeof(*disk_ce),
>> +               ntoh_l(*filecrc)))
>> +               return -1;
>> +
>> +       return 0;
>> +}
>
> Last thought before book+bed time. I wonder if moving the name part to
> the end of the entry (i.e. chaging on disk format) would simplify this
> code. The new ondisk_cache_entry would be something like this
>
> struct ondisk_cache_entry {
>    uint16_t flags;
>    uint16_t mode;
>    struct cache_time mtime;
>    uint32_t size;
>    int stat_crc;
>    unsigned char sha1[20];
>    char name[FLEX_ARRAY];
> };

I think it simplifies it a bit, but not too much, the only thing I see avoiding the use of the name variable. I think it will also simplify the writing code a bit. The only negative part would be for bisecting the index, but that would still be possible, and only slightly more complicated. I'll give it a try tomorrow and check if it's worth it.

Previous: Duy NguyenNext: Duy Nguyen
Message 32 of 55 in “Index-v5”
  1. 00/24 Index-v5Thomas Gummerer, Aug 18, 2013
  2. 01/24 t2104: Don't fail for index versions other than [23]Thomas Gummerer, Aug 18, 2013
  3. 02/24 read-cache: use fixed width integer typesThomas Gummerer, Aug 18, 2013
  4. Eric SunshineAug 18, 2013
  5. Junio C HamanoAug 20, 2013
  6. Thomas GummererAug 21, 2013
  7. 03/24 read-cache: split index file version specific functionalityThomas Gummerer, Aug 18, 2013
  8. 04/24 read-cache: clear version in discard_index()Thomas Gummerer, Aug 18, 2013
  9. Junio C HamanoAug 20, 2013
  10. Thomas GummererAug 21, 2013
  11. 05/24 read-cache: move index v2 specific functions to their own fileThomas Gummerer, Aug 18, 2013
  12. 06/24 read-cache: Don't compare uid, gid and ino on cygwinThomas Gummerer, Aug 18, 2013
  13. Ramsay JonesAug 18, 2013
  14. Thomas GummererAug 20, 2013
  15. 07/24 read-cache: Re-read index if index file changedThomas Gummerer, Aug 18, 2013
  16. 08/24 add documentation for the index apiThomas Gummerer, Aug 18, 2013
  17. Eric SunshineAug 18, 2013
  18. 09/24 read-cache: add index reading apiThomas Gummerer, Aug 18, 2013
  19. 10/24 make sure partially read index is not changedThomas Gummerer, Aug 18, 2013
  20. Eric SunshineAug 18, 2013
  21. Thomas GummererAug 20, 2013
  22. 11/24 grep.c: use index apiThomas Gummerer, Aug 18, 2013
  23. 12/24 ls-files.c: use index apiThomas Gummerer, Aug 18, 2013
  24. 13/24 documentation: add documentation of the index-v5 file formatThomas Gummerer, Aug 18, 2013
  25. 14/24 read-cache: make in-memory format aware of stat_crcThomas Gummerer, Aug 18, 2013
  26. 15/24 read-cache: read index-v5Thomas Gummerer, Aug 18, 2013
  27. Eric SunshineAug 19, 2013
  28. Duy NguyenAug 20, 2013
  29. Thomas GummererAug 20, 2013
  30. Duy NguyenAug 21, 2013
  31. Duy NguyenAug 20, 2013
  32. Thomas GummererAug 20, 2013
  33. Duy NguyenAug 23, 2013
  34. 16/24 read-cache: read resolve-undo dataThomas Gummerer, Aug 18, 2013
  35. Eric SunshineAug 19, 2013
  36. 17/24 read-cache: read cache-tree in index-v5Thomas Gummerer, Aug 18, 2013
  37. Duy NguyenAug 24, 2013
  38. Thomas GummererNov 25, 2013
  39. 18/24 read-cache: write index-v5Thomas Gummerer, Aug 18, 2013
  40. Duy NguyenAug 24, 2013
  41. Thomas GummererNov 25, 2013
  42. Duy NguyenAug 24, 2013
  43. Duy NguyenAug 24, 2013
  44. 19/24 read-cache: write index-v5 cache-tree dataThomas Gummerer, Aug 18, 2013
  45. 20/24 read-cache: write resolve-undo data for index-v5Thomas Gummerer, Aug 18, 2013
  46. 21/24 update-index.c: rewrite index when index-version is givenThomas Gummerer, Aug 18, 2013
  47. 22/24 p0003-index.sh: add perf test for the index formatsThomas Gummerer, Aug 18, 2013
  48. 23/24 introduce GIT_INDEX_VERSION environment variableThomas Gummerer, Aug 18, 2013
  49. Duy NguyenAug 21, 2013
  50. Thomas GummererAug 21, 2013
  51. 24/24 test-lib: allow setting the index format versionThomas Gummerer, Aug 18, 2013
  52. Duy NguyenAug 24, 2013
  53. Junio C HamanoAug 25, 2013
  54. Duy NguyenAug 25, 2013
  55. Thomas GummererAug 31, 2013

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