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
#require test-repo
$ . "$TESTDIR/helpers-testrepo.sh"
Sanity check check-config.py
$ cat > testfile.py << EOF
> # Good
> foo = ui.config('ui', 'username')
> # Missing
> foo = ui.config('ui', 'doesnotexist')
> # Missing different type
> foo = ui.configint('ui', 'missingint')
> # Missing with default value
> foo = ui.configbool('ui', 'missingbool1', default=True)
> foo = ui.configbool('ui', 'missingbool2', False)
> # Inconsistent values for defaults.
> foo = ui.configint('ui', 'intdefault', default=1)
> foo = ui.configint('ui', 'intdefault', default=42)
> # Can suppress inconsistent value error
> foo = ui.configint('ui', 'intdefault2', default=1)
> # inconsistent config: ui.intdefault2
> foo = ui.configint('ui', 'intdefault2', default=42)
> EOF
$ cat > files << EOF
> mercurial/helptext/config.txt
> $TESTTMP/testfile.py
> EOF
$ cd "$TESTDIR"/..
$ "$PYTHON" contrib/check-config.py < $TESTTMP/files
foo = ui.configint('ui', 'intdefault', default=42)
conflict on ui.intdefault: ('int', '42') != ('int', '1')
at $TESTTMP/testfile.py:12:
undocumented: ui.doesnotexist (str)
undocumented: ui.intdefault (int) [42]
undocumented: ui.intdefault2 (int) [42]
undocumented: ui.missingbool1 (bool) [True]
undocumented: ui.missingbool2 (bool)
undocumented: ui.missingint (int)
New errors are not allowed. Warnings are strongly discouraged.
$ testrepohg files "set:(**.py or **.txt) - tests/**" | sed 's|\\|/|g' |
> "$PYTHON" contrib/check-config.py