view mercurial/help/extensions.txt @ 39627:ee7ee0c516ca

narrow: intersect provided matcher with narrowmatcher in `hg diff`

This provides significant speedups when running diff, and no change in behavior
that I'm aware of (or that the tests found). I tested with a repo that I started
using narrow in after it was created and attempted to run `hg diff -c .` and
similar commands in it on a commit that had files not in the narrowspec.

Timing numbers below, using a similar setup as my previous commits.
before=9db85644, m-u is mozilla-unified at eb39298e432d (flatmanifest) and
0553b7f29eaf (treemanifest). l-d-r is a repo simulating a situation I've
encountered where there's one directory with 30k+ subdirectories. N means
narrow, T means treemanifest. The narrowspec is pretty small when in use, and
importantly the narrowspec is applied *after* doing the initial checkout
(without narrowing), so all of these files exist in the filesystem, which is not
normally the case if someone has been using narrow for the entire life of the
clone.

Anything less than a 5% difference in performance is most likely noise.

    diff --git:
    repo  | N | T | before (mean +- stdev) | after (mean +- stdev) | % of before
    ------+---+---+------------------------+-----------------------+------------
    m-u   |   |   | 1.292 s +-  0.009 s    | 1.295 s +-  0.010 s   | 100.2%
    m-u   |   | x | 1.296 s +-  0.042 s    | 1.299 s +-  0.026 s   | 100.2%
    m-u   | x |   | 1.292 s +-  0.010 s    | 1.297 s +-  0.021 s   | 100.4%
    m-u   | x | x | 84.2 ms +-   1.2 ms    | 83.6 ms +-   0.2 ms   |  99.3%
    l-d-r |   |   | 188.7 ms +-   2.7 ms   | 188.8 ms +-   2.0 ms  | 100.1%
    l-d-r |   | x | 189.9 ms +-   1.5 ms   | 189.4 ms +-   1.2 ms  |  99.7%
    l-d-r | x |   | 97.1 ms +-   1.0 ms    | 87.1 ms +-   1.0 ms   |  89.7% <--
    l-d-r | x | x | 96.9 ms +-   0.8 ms    | 87.2 ms +-   0.7 ms   |  90.0% <--

    diff -c . --git:
    repo  | N | T | before (mean +- stdev) | after (mean +- stdev) | % of before
    ------+---+---+------------------------+-----------------------+------------
    m-u   |   |   | 231.6 ms +-   3.1 ms   | 228.9 ms +-   1.6 ms  |  98.8%
    m-u   |   | x | 150.5 ms +-   1.7 ms   | 150.7 ms +-   1.4 ms  | 100.1%
    m-u   | x |   | 233.7 ms +-   2.4 ms   | 232.2 ms +-   1.9 ms  |  99.4%
    m-u   | x | x | 126.1 ms +-   1.2 ms   | 126.8 ms +-   1.2 ms  | 100.6%
    l-d-r |   |   | 82.1 ms +-   2.0 ms    | 81.8 ms +-   1.4 ms   |  99.6%
    l-d-r |   | x | 3.732 s +-  0.020 s    | 3.746 s +-  0.027 s   | 100.4%
    l-d-r | x |   | 83.1 ms +-   0.8 ms    | 107.6 ms +-   2.4 ms  | 129.5% <--
    l-d-r | x | x | 758.2 ms +-  38.8 ms   | 188.5 ms +-   1.8 ms  |  24.9% <--

    rebase -r . --keep -d .^^:
    repo  | N | T | before (mean +- stdev) | after (mean +- stdev) | % of before
    ------+---+---+------------------------+-----------------------+------------
    m-u   |   |   | 5.532 s +-  0.087 s    | 5.496 s +-  0.016 s   |  99.3%
    m-u   |   | x | 5.554 s +-  0.061 s    | 5.532 s +-  0.013 s   |  99.6%
    m-u   | x |   | 5.602 s +-  0.134 s    | 5.508 s +-  0.035 s   |  98.3%
    m-u   | x | x | 582.2 ms +-  15.2 ms   | 572.9 ms +-  12.0 ms  |  98.4%
    l-d-r |   |   | 629.5 ms +-  12.3 ms   | 622.5 ms +-   7.3 ms  |  98.9%
    l-d-r |   | x | 6.173 s +-  0.062 s    | 6.185 s +-  0.076 s   | 100.2%
    l-d-r | x |   | 274.5 ms +-  10.0 ms   | 272.1 ms +-   6.2 ms  |  99.1%
    l-d-r | x | x | 4.835 s +-  0.056 s    | 4.826 s +-  0.034 s   |  99.8%

    status --change . --copies:
    repo  | N | T | before (mean +- stdev) | after (mean +- stdev) | % of before
    ------+---+---+------------------------+-----------------------+------------
    m-u   |   |   | 214.4 ms +-   1.4 ms   | 212.2 ms +-   1.7 ms  |  99.0%
    m-u   |   | x | 130.9 ms +-   1.2 ms   | 131.7 ms +-   1.1 ms  | 100.6%
    m-u   | x |   | 215.0 ms +-   2.1 ms   | 214.9 ms +-   2.7 ms  | 100.0%
    m-u   | x | x | 109.5 ms +-   2.3 ms   | 107.8 ms +-   0.9 ms  |  98.4%
    l-d-r |   |   | 79.6 ms +-   0.9 ms    | 79.8 ms +-   1.6 ms   | 100.3%
    l-d-r |   | x | 3.799 s +-  0.037 s    | 3.928 s +-  0.021 s   | 103.4% <--?
    l-d-r | x |   | 82.7 ms +-   0.7 ms    | 83.2 ms +-   1.0 ms   | 100.6%
    l-d-r | x | x | 746.8 ms +-   6.1 ms   | 739.0 ms +-   4.2 ms  |  99.0%

    status --copies:
    repo  | N | T | before (mean +- stdev) | after (mean +- stdev) | % of before
    ------+---+---+------------------------+-----------------------+------------
    m-u   |   |   | 1.884 s +-  0.012 s    | 1.885 s +-  0.013 s   | 100.1%
    m-u   |   | x | 1.897 s +-  0.027 s    | 1.909 s +-  0.077 s   | 100.6%
    m-u   | x |   | 1.886 s +-  0.021 s    | 1.891 s +-  0.030 s   | 100.3%
    m-u   | x | x | 92.0 ms +-   0.7 ms    | 92.4 ms +-   0.4 ms   | 100.4%
    l-d-r |   |   | 570.3 ms +-  18.7 ms   | 552.2 ms +-   4.5 ms  |  96.8%
    l-d-r |   | x | 568.9 ms +-  16.1 ms   | 567.2 ms +-  11.9 ms  |  99.7%
    l-d-r | x |   | 171.1 ms +-   2.5 ms   | 170.4 ms +-   1.2 ms  |  99.6%
    l-d-r | x | x | 171.6 ms +-   3.4 ms   | 171.5 ms +-   1.7 ms  |  99.9%

    update $rev^; ~/src/hg/hg{hg}/hg update $rev:
    repo  | N | T | before (mean +- stdev) | after (mean +- stdev) | % of before
    ------+---+---+------------------------+-----------------------+------------
    m-u   |   |   | 3.107 s +-  0.017 s    | 3.116 s +-  0.012 s   | 100.3%
    m-u   |   | x | 2.943 s +-  0.010 s    | 2.945 s +-  0.019 s   | 100.1%
    m-u   | x |   | 3.116 s +-  0.033 s    | 3.118 s +-  0.027 s   | 100.1%
    m-u   | x | x | 318.5 ms +-   2.7 ms   | 320.8 ms +-   4.8 ms  | 100.7%
    l-d-r |   |   | 428.9 ms +-   4.4 ms   | 429.5 ms +-   4.0 ms  | 100.1%
    l-d-r |   | x | 9.593 s +-  0.081 s    | 9.869 s +-  0.043 s   | 102.9%
    l-d-r | x |   | 253.2 ms +-   3.6 ms   | 254.0 ms +-   2.8 ms  | 100.3%
    l-d-r | x | x | 1.613 s +-  0.009 s    | 1.630 s +-  0.017 s   | 101.1%

Differential Revision: https://phab.mercurial-scm.org/D4587

Mercurial has the ability to add new features through the use of
extensions. Extensions may add new commands, add options to
existing commands, change the default behavior of commands, or
implement hooks.

To enable the "foo" extension, either shipped with Mercurial or in the
Python search path, create an entry for it in your configuration file,
like this::

  [extensions]
  foo =

You may also specify the full path to an extension::

  [extensions]
  myfeature = ~/.hgext/myfeature.py

See :hg:`help config` for more information on configuration files.

Extensions are not loaded by default for a variety of reasons:
they can increase startup overhead; they may be meant for advanced
usage only; they may provide potentially dangerous abilities (such
as letting you destroy or modify history); they might not be ready
for prime time; or they may alter some usual behaviors of stock
Mercurial. It is thus up to the user to activate extensions as
needed.

To explicitly disable an extension enabled in a configuration file of
broader scope, prepend its path with !::

  [extensions]
  # disabling extension bar residing in /path/to/extension/bar.py
  bar = !/path/to/extension/bar.py
  # ditto, but no path was supplied for extension baz
  baz = !