view tests/ls-l.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

#!/usr/bin/env python3

# like ls -l, but do not print date, user, or non-common mode bit, to avoid
# using globs in tests.
from __future__ import absolute_import, print_function

import os
import stat
import sys


def modestr(st):
    mode = st.st_mode
    result = ''
    if mode & stat.S_IFDIR:
        result += 'd'
    else:
        result += '-'
    for owner in ['USR', 'GRP', 'OTH']:
        for action in ['R', 'W', 'X']:
            if mode & getattr(stat, 'S_I%s%s' % (action, owner)):
                result += action.lower()
            else:
                result += '-'
    return result


def sizestr(st):
    if st.st_mode & stat.S_IFREG:
        return '%7d' % st.st_size
    else:
        # do not show size for non regular files
        return ' ' * 7


os.chdir((sys.argv[1:] + ['.'])[0])

for name in sorted(os.listdir('.')):
    st = os.stat(name)
    print('%s %s %s' % (modestr(st), sizestr(st), name))