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Re: [PATCH 3/6] strbuf_getwholeline: use getc_unlocked

From
Jeff King <peff@peff.net>
Date
Apr 5, 2015, 18:24 UTC
Message-ID
<20150405182401.GA13096@peff.net>
In-Reply-To
<CACsJy8Biv6D2foDxpn-CZhEsjn3WsPV=_A3UOnT4+1LVrpRnTw@mail.gmail.com>
On Sun, Apr 05, 2015 at 09:36:04PM +0700, Duy Nguyen wrote:
Show 11 quoted lines
> On Sun, Apr 5, 2015 at 11:56 AM, Jeff King <peff@peff.net> wrote:
> > So we'd have to either:
> >
> >   1. Decide that doesn't matter.
> >
> >   2. Have callers specify a "damn the NULs, I want it fast" flag.
> 
> 2+. Avoid FILE* interface and go with syscalls for reading
> packed-refs? If mmaping the entire file could be a problem for some
> platform because it's too large, we have code for reading (with
> bufferring) from fd somewhere, e.g. index-pack.

There's strbuf_getwholeline_fd, but it's horrifically inefficient (one syscall per character). But the other option is to implement your own buffering, and we're generally better off letting stdio do that for us (the exception here is that stdio does not have a good NUL-safe "read until X" function).

-Peff
Previous: Duy NguyenNext: Junio C Hamano
Message 10 of 44 in “address packed-refs speed regressions”
  1. 0/6 address packed-refs speed regressionsJeff King, Apr 5, 2015
  2. 1/6 strbuf_getwholeline: use getc macroJeff King, Apr 5, 2015
  3. 2/6 git-compat-util: add fallbacks for unlocked stdioJeff King, Apr 5, 2015
  4. 3/6 strbuf_getwholeline: use getc_unlockedJeff King, Apr 5, 2015
  5. Jeff KingApr 5, 2015
  6. Jeff KingApr 5, 2015
  7. Jeff KingApr 5, 2015
  8. Junio C HamanoApr 5, 2015
  9. Duy NguyenApr 5, 2015
  10. Jeff KingApr 5, 2015
  11. Junio C HamanoApr 5, 2015
  12. Rasmus VillemoesApr 7, 2015
  13. Jeff KingApr 7, 2015
  14. Rasmus VillemoesApr 7, 2015
  15. Jeff KingApr 8, 2015
  16. 4/6 strbuf: add an optimized 1-character strbuf_growJeff King, Apr 5, 2015
  17. Eric SunshineApr 6, 2015
  18. Jeff KingApr 6, 2015
  19. 5/6 t1430: add another refs-escape testJeff King, Apr 5, 2015
  20. 6/6 refname_is_safe: avoid expensive normalize_path_copy callJeff King, Apr 5, 2015
  21. René ScharfeApr 5, 2015
  22. Jeff KingApr 5, 2015
  23. Jeff KingApr 5, 2015
  24. René ScharfeApr 5, 2015
  25. René ScharfeApr 5, 2015
  26. Jeff KingApr 6, 2015
  27. 0/9 address packed-refs speed regressionsJeff King, Apr 16, 2015
  28. 1/9 strbuf_getwholeline: use getc macroJeff King, Apr 16, 2015
  29. 2/9 git-compat-util: add fallbacks for unlocked stdioJeff King, Apr 16, 2015
  30. 3/9 strbuf_getwholeline: use getc_unlockedJeff King, Apr 16, 2015
  31. 4/9 config: use getc_unlocked when reading from fileJeff King, Apr 16, 2015
  32. 5/9 strbuf_addch: avoid calling strbuf_growJeff King, Apr 16, 2015
  33. 6/9 strbuf_getwholeline: avoid calling strbuf_growJeff King, Apr 16, 2015
  34. 7/9 strbuf_getwholeline: use getdelim if it is availableJeff King, Apr 16, 2015
  35. Eric SunshineApr 17, 2015
  36. Jeff KingApr 21, 2015
  37. Eric SunshineMay 8, 2015
  38. Jeff KingMay 9, 2015
  39. Eric SunshineJun 2, 2015
  40. Johannes SchindelinApr 22, 2015
  41. Jeff KingApr 22, 2015
  42. 8/9 read_packed_refs: avoid double-checking sane refsJeff King, Apr 16, 2015
  43. 9/9 t1430: add another refs-escape testJeff King, Apr 16, 2015
  44. Jeff KingApr 16, 2015

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