contrib/memory.py

status: intersect matcher with narrow matcher instead of filtering afterwards

I seem to have done a very naive move of the code from the narrow
extension into core in e411774a2e0f (narrow: move status-filtering to
core and to ctx, 2018-08-02). It seems obvious that a better way is to
intersect the matchers.

Note that this means that when requesting status for the working
directory in a narrow repo, we now pass the narrow matcher (possibly
intersected with a user-provided matcher) into _buildstatus() and then
into dirstate.status() and dirstate.walk(), which will the intersect
it again with the narrow matcher. That's functionally fine, but
wasteful. I hope to later remove the dirstate wrapping that adds the
second layer of matcher intersection.

Differential Revision: https://phab.mercurial-scm.org/D4897

# memory.py - track memory usage
#
# Copyright 2009 Matt Mackall <[e-mail]> and others
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

'''helper extension to measure memory usage

Reads current and peak memory usage from ``/proc/self/status`` and
prints it to ``stderr`` on exit.
'''

from __future__ import absolute_import

def memusage(ui):
    """Report memory usage of the current process."""
    result = {'peak': 0, 'rss': 0}
    with open('/proc/self/status', 'r') as status:
        # This will only work on systems with a /proc file system
        # (like Linux).
        for line in status:
            parts = line.split()
            key = parts[0][2:-1].lower()
            if key in result:
                result[key] = int(parts[1])
    ui.write_err(", ".join(["%s: %.1f MiB" % (k, v / 1024.0)
                            for k, v in result.iteritems()]) + "\n")

def extsetup(ui):
    ui.atexit(memusage, ui)