annotate mercurial/helptext/hgignore.5.txt @ 47120:7109a38830c9

dirstate-tree: Fold "tracked descendants" counter update in main walk

For the purpose of implementing `has_tracked_dir` (which means "has tracked
descendants) without an expensive sub-tree traversal, we maintaing a counter
of tracked descendants on each "directory" node of the tree-shaped dirstate.

Before this changeset, mutating or inserting a node at a given path would
involve:

* Walking the tree from root through ancestors to find the node or the spot
  where to insert it
* Looking at the previous node if any to decide what counter update is needed
* Performing any node mutation
* Walking the tree *again* to update counters in ancestor nodes

When profiling `hg status` on a large repo, this second walk takes times
while loading a the dirstate from disk.

It turns out we have enough information to decide before he first tree walk
what counter update is needed. This changeset merges the two walks, gaining
~10% of the total time for `hg update` (in the same hyperfine benchmark as
the previous changeset).

---

Profiling was done by compiling with this `.cargo/config`:

    [profile.release]
    debug = true

then running with:

    py-spy record -r 500 -n -o /tmp/hg.json --format speedscope -- \
    ./hg status -R $REPO --config experimental.dirstate-tree.in-memory=1

then visualizing the recorded JSON file in https://www.speedscope.app/

Differential Revision: https://phab.mercurial-scm.org/D10554

==========
 hgignore
==========

---------------------------------
syntax for Mercurial ignore files
---------------------------------

:Author:         Vadim Gelfer <[e-mail]>
:Organization:   Mercurial
:Manual section: 5
:Manual group:   Mercurial Manual

.. include:: hgignore.5.gendoc.txt

Author
======
Vadim Gelfer <[e-mail]>

Mercurial was written by Olivia Mackall <[e-mail]>.

See Also
========
|hg(1)|_, |hgrc(5)|_

Copying
=======
This manual page is copyright 2006 Vadim Gelfer.
Mercurial is copyright 2005-2021 Olivia Mackall.
Free use of this software is granted under the terms of the GNU General
Public License version 2 or any later version.

.. include:: common.txt