view mercurial/help/pager.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

Some Mercurial commands can produce a lot of output, and Mercurial will
attempt to use a pager to make those commands more pleasant.

To set the pager that should be used, set the application variable::

  [pager]
  pager = less -FRX

If no pager is set in the user or repository configuration, Mercurial uses the
environment variable $PAGER. If $PAGER is not set, pager.pager from the default
or system configuration is used. If none of these are set, a default pager will
be used, typically `less` on Unix and `more` on Windows.

.. container:: windows

  On Windows, `more` is not color aware, so using it effectively disables color.
  MSYS and Cygwin shells provide `less` as a pager, which can be configured to
  support ANSI color codes.  See :hg:`help config.color.pagermode` to configure
  the color mode when invoking a pager.

You can disable the pager for certain commands by adding them to the
pager.ignore list::

  [pager]
  ignore = version, help, update

To ignore global commands like :hg:`version` or :hg:`help`, you have
to specify them in your user configuration file.

To control whether the pager is used at all for an individual command,
you can use --pager=<value>:

  - use as needed: `auto`.
  - require the pager: `yes` or `on`.
  - suppress the pager: `no` or `off` (any unrecognized value
    will also work).

To globally turn off all attempts to use a pager, set::

  [ui]
  paginate = never

which will prevent the pager from running.