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
# debugshell extension
"""a python shell with repo, changelog & manifest objects"""
from __future__ import absolute_import
import code
import mercurial
import sys
from mercurial import (
demandimport,
pycompat,
registrar,
)
cmdtable = {}
command = registrar.command(cmdtable)
def pdb(ui, repo, msg, **opts):
objects = {
'mercurial': mercurial,
'repo': repo,
'cl': repo.changelog,
'mf': repo.manifestlog,
}
code.interact(msg, local=objects)
def ipdb(ui, repo, msg, **opts):
import IPython
cl = repo.changelog
mf = repo.manifestlog
cl, mf # use variables to appease pyflakes
IPython.embed()
@command(b'debugshell|dbsh', [])
def debugshell(ui, repo, **opts):
bannermsg = "loaded repo : %s\n" "using source: %s" % (
pycompat.sysstr(repo.root),
mercurial.__path__[0],
)
pdbmap = {'pdb': 'code', 'ipdb': 'IPython'}
debugger = ui.config(b"ui", b"debugger")
if not debugger:
debugger = 'pdb'
else:
debugger = pycompat.sysstr(debugger)
# if IPython doesn't exist, fallback to code.interact
try:
with demandimport.deactivated():
__import__(pdbmap[debugger])
except ImportError:
ui.warnnoi18n(
b"%s debugger specified but %s module was not found\n"
% (debugger, pdbmap[debugger])
)
debugger = b'pdb'
getattr(sys.modules[__name__], debugger)(ui, repo, bannermsg, **opts)