contrib/memory.py

revlog: open files in 'r+' instead of 'a+'

The code doing actual writing is already doing the necessary seeking, so we
could safely use 'r+'. This make the file objecs usable in more situation, like
updating the sidedata information during pull.


revlog: forcibly move the file cursor at the right location before writing

This is a paranoid change in case the changelog computation moved the cursors
under our feets.

This is not known to happens right now.

Differential Revision: https://phab.mercurial-scm.org/D10608

# memory.py - track memory usage
#
# Copyright 2009 Olivia 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)