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Re: [PATCH 12/12] builtin/commit-graph.c: introduce '--max-new-filters=<n>'

From
Taylor Blau <me@ttaylorr.com>
Date
Sep 11, 2020, 18:59 UTC
Message-ID
<20200911185934.GA2871@xor.lan>
In-Reply-To
<20200911175216.GA2693949@coredump.intra.peff.net>
On Fri, Sep 11, 2020 at 01:52:16PM -0400, Jeff King wrote:
Show 8 quoted lines
> On Wed, Sep 09, 2020 at 11:24:00AM -0400, Taylor Blau wrote:
> > +With the `--max-new-filters=<n>` option, generate at most `n` new Bloom
> > +filters (if `--changed-paths` is specified). If `n` is `-1`, no limit is
> > +enforced. Commits whose filters are not calculated are stored as a
> > +length zero Bloom filter, and their bit is marked in the `BFXL` chunk.
> > +Overrides the `commitGraph.maxNewFilters` configuration.
>
> The BFXL chunk doesn't exist anymore in this iteration, right?
Ack; I'll have to drop that.
Show 20 quoted lines
> I wondered about having a user-facing "-1" here. My gut feeling is that
> we usually use "0" to mean "no limit" in other places, and it probably
> make sense to be consistent. It does look like we use both, though, and
> I'm having trouble formulating a grep pattern to find examples that
> doesn't produce a lot of noise.
>
> These are "0 is no limit":
>
>   pack.windowMemory
>   pack.deltaCacheSize
>   git-daemon --max-connections
>
> These are "-1 is no limit":
>
>   git-grep --max-depth
>   rev-list --max-parents (I think?)
>
> So I dunno. It's a pretty minor thing, but I think it's good to aim for
> consistency, and since this is user-facing we won't be able to change it
> later.

I think that we have to treat "-1" as the no-limit indicator, or otherwise we'd have to specify some other way to say we don't want to generate any filters. With this patch, users can write:

  $ git commit-graph write --changed-paths .. --max-new-filters=0

to generate a commit-graph without writing any new filters. This is important to be able to do since we also have a 'commitGraph.maxNewFilters' configuration, which callers may want to override.

You may wonder why you wouldn't just write '--no-changed-paths' instead. Doing so would indeed generate no new filters, but it also wouldn't write any already existing filters into a new graph which is important when rolling up graph layers that already have incrementals, for example with '--split'.

I'm happy to include all or none of this in a re-rolled commit message if you think it's relevant, too.

> -Peff

Thanks, Taylor

Previous: Jeff KingNext: Taylor Blau
Message 6 of 75 in “more miscellaneous Bloom filter improvements, redux”
  1. 00/12 more miscellaneous Bloom filter improvements, reduxTaylor Blau, Sep 9, 2020
  2. 03/12 commit-graph: pass a 'struct repository *' in more placesTaylor Blau, Sep 9, 2020
  3. 11/12 commit-graph: rename 'split_commit_graph_opts'Taylor Blau, Sep 9, 2020
  4. 12/12 builtin/commit-graph.c: introduce '--max-new-filters=<n>'Taylor Blau, Sep 9, 2020
  5. Jeff KingSep 11, 2020
  6. Taylor BlauSep 11, 2020
  7. Taylor BlauSep 11, 2020
  8. Taylor BlauSep 14, 2020
  9. Derrick StoleeSep 14, 2020
  10. Taylor BlauSep 14, 2020
  11. Derrick StoleeSep 15, 2020
  12. Taylor BlauSep 15, 2020
  13. Junio C HamanoSep 15, 2020
  14. Taylor BlauSep 15, 2020
  15. Jeff KingSep 11, 2020
  16. Junio C HamanoSep 11, 2020
  17. 04/12 t/helper/test-read-graph.c: prepare repo settingsTaylor Blau, Sep 9, 2020
  18. 05/12 commit-graph: respect 'commitGraph.readChangedPaths'Taylor Blau, Sep 9, 2020
  19. 08/12 bloom: use provided 'struct bloom_filter_settings'Taylor Blau, Sep 9, 2020
  20. 06/12 commit-graph.c: store maximum changed pathsTaylor Blau, Sep 9, 2020
  21. 09/12 bloom/diff: properly short-circuit on max_changesTaylor Blau, Sep 9, 2020
  22. 10/12 bloom: encode out-of-bounds filters as non-emptyTaylor Blau, Sep 9, 2020
  23. Taylor BlauSep 10, 2020
  24. Taylor BlauSep 10, 2020
  25. Derrick StoleeSep 11, 2020
  26. 07/12 bloom: split 'get_bloom_filter()' in twoTaylor Blau, Sep 9, 2020
  27. 02/12 t4216: use an '&&'-chainTaylor Blau, Sep 9, 2020
  28. 01/12 commit-graph: introduce 'get_bloom_filter_settings()'Taylor Blau, Sep 9, 2020
  29. 00/13 more miscellaneous Bloom filter improvements, reduxTaylor Blau, Sep 16, 2020
  30. 04/13 t/helper/test-read-graph.c: prepare repo settingsTaylor Blau, Sep 16, 2020
  31. 03/13 commit-graph: pass a 'struct repository *' in more placesTaylor Blau, Sep 16, 2020
  32. 05/13 commit-graph: respect 'commitGraph.readChangedPaths'Taylor Blau, Sep 16, 2020
  33. 06/13 commit-graph.c: store maximum changed pathsTaylor Blau, Sep 16, 2020
  34. 02/13 t4216: use an '&&'-chainTaylor Blau, Sep 16, 2020
  35. 01/13 commit-graph: introduce 'get_bloom_filter_settings()'Taylor Blau, Sep 16, 2020
  36. 07/13 bloom: split 'get_bloom_filter()' in twoTaylor Blau, Sep 16, 2020
  37. 08/13 bloom: use provided 'struct bloom_filter_settings'Taylor Blau, Sep 16, 2020
  38. 10/13 bloom: encode out-of-bounds filters as non-emptyTaylor Blau, Sep 16, 2020
  39. SZEDER GáborSep 17, 2020
  40. Taylor BlauSep 17, 2020
  41. Junio C HamanoSep 18, 2020
  42. Taylor BlauSep 18, 2020
  43. 11/13 commit-graph: rename 'split_commit_graph_opts'Taylor Blau, Sep 16, 2020
  44. 12/13 builtin/commit-graph.c: introduce '--max-new-filters=<n>'Taylor Blau, Sep 16, 2020
  45. SZEDER GáborSep 18, 2020
  46. Taylor BlauSep 18, 2020
  47. 09/13 bloom/diff: properly short-circuit on max_changesTaylor Blau, Sep 16, 2020
  48. 13/13 commit-graph: introduce 'commitGraph.maxNewFilters'Taylor Blau, Sep 16, 2020
  49. Derrick StoleeSep 16, 2020
  50. Junio C HamanoSep 16, 2020
  51. Taylor BlauSep 17, 2020
  52. Junio C HamanoSep 17, 2020
  53. Taylor BlauSep 17, 2020
  54. Taylor BlauSep 17, 2020
  55. Derrick StoleeSep 17, 2020
  56. 00/13 more miscellaneous Bloom filter improvements, reduxTaylor Blau, Sep 18, 2020
  57. 01/13 commit-graph: introduce 'get_bloom_filter_settings()'Taylor Blau, Sep 18, 2020
  58. 03/13 commit-graph: pass a 'struct repository *' in more placesTaylor Blau, Sep 18, 2020
  59. 02/13 t4216: use an '&&'-chainTaylor Blau, Sep 18, 2020
  60. 05/13 commit-graph: respect 'commitGraph.readChangedPaths'Taylor Blau, Sep 18, 2020
  61. 04/13 t/helper/test-read-graph.c: prepare repo settingsTaylor Blau, Sep 18, 2020
  62. 08/13 bloom: use provided 'struct bloom_filter_settings'Taylor Blau, Sep 18, 2020
  63. SZEDER GáborSep 18, 2020
  64. Taylor BlauSep 18, 2020
  65. 07/13 bloom: split 'get_bloom_filter()' in twoTaylor Blau, Sep 18, 2020
  66. 06/13 commit-graph.c: store maximum changed pathsTaylor Blau, Sep 18, 2020
  67. 10/13 bloom: encode out-of-bounds filters as non-emptyTaylor Blau, Sep 18, 2020
  68. 11/13 commit-graph: rename 'split_commit_graph_opts'Taylor Blau, Sep 18, 2020
  69. 13/13 commit-graph: introduce 'commitGraph.maxNewFilters'Taylor Blau, Sep 18, 2020
  70. Taylor BlauSep 18, 2020
  71. Junio C HamanoSep 18, 2020
  72. 12/13 builtin/commit-graph.c: introduce '--max-new-filters=<n>'Taylor Blau, Sep 18, 2020
  73. 09/13 bloom/diff: properly short-circuit on max_changesTaylor Blau, Sep 18, 2020
  74. Taylor BlauSep 18, 2020
  75. Taylor BlauSep 18, 2020

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