Mercurial > hg
view tests/svn-safe-append.py @ 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
author | Simon Sapin <simon.sapin@octobus.net> |
---|---|
date | Fri, 30 Apr 2021 14:22:14 +0200 |
parents | c102b704edb5 |
children | 6000f5b25c9b |
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#!/usr/bin/env python3 from __future__ import absolute_import __doc__ = """Same as `echo a >> b`, but ensures a changed mtime of b. Without this svn will not detect workspace changes.""" import os import stat import sys if sys.version_info[0] >= 3: text = os.fsencode(sys.argv[1]) fname = os.fsencode(sys.argv[2]) else: text = sys.argv[1] fname = sys.argv[2] f = open(fname, "ab") try: before = os.fstat(f.fileno())[stat.ST_MTIME] f.write(text) f.write(b"\n") finally: f.close() inc = 1 now = os.stat(fname)[stat.ST_MTIME] while now == before: t = now + inc inc += 1 os.utime(fname, (t, t)) now = os.stat(fname)[stat.ST_MTIME]