contrib/memory.py

update: use context manager for config override (API)

Note that update wasn't resetting the value before, so any extensions
that called commands.update() and relied on ui.forcemerge being set
after it returned would now have to set it themselves.

(There technically a small API change in all of the patches in this
series, I believe: If extensions relied on the methods to *clear*
ui.forcemerge, then they would have to do that themselves now, because
ui.configoverride() actually restores the previous config, it doesn't
just clear it like these functions did before.)

Differential Revision: https://phab.mercurial-scm.org/D3741

# 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)