view tests/test-hgwebdir-paths.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

from __future__ import absolute_import

import os
from mercurial import (
    hg,
    ui as uimod,
)
from mercurial.hgweb import hgwebdir_mod

hgwebdir = hgwebdir_mod.hgwebdir

os.mkdir(b'webdir')
os.chdir(b'webdir')

webdir = os.path.realpath(b'.')

u = uimod.ui.load()
hg.repository(u, b'a', create=1)
hg.repository(u, b'b', create=1)
os.chdir(b'b')
hg.repository(u, b'd', create=1)
os.chdir(b'..')
hg.repository(u, b'c', create=1)
os.chdir(b'..')

paths = {
    b't/a/': b'%s/a' % webdir,
    b'b': b'%s/b' % webdir,
    b'coll': b'%s/*' % webdir,
    b'rcoll': b'%s/**' % webdir,
}

config = os.path.join(webdir, b'hgwebdir.conf')
configfile = open(config, 'wb')
configfile.write(b'[paths]\n')
for k, v in paths.items():
    configfile.write(b'%s = %s\n' % (k, v))
configfile.close()

confwd = hgwebdir(config)
dictwd = hgwebdir(paths)

assert len(confwd.repos) == len(dictwd.repos), 'different numbers'
assert len(confwd.repos) == 9, 'expected 9 repos, found %d' % len(confwd.repos)

found = dict(confwd.repos)
for key, path in dictwd.repos:
    assert key in found, 'repository %s was not found' % key
    assert found[key] == path, 'different paths for repo %s' % key