view contrib/memory.py @ 49149:006688e36e12 stable

rhg: use `Command::exec` instead of `Command::status`

`rhg` is supposed to be a transparent executable, using a subprocess defeats
that purpose. See inline comments for more details.

This also introduces the `which` crate to check if the fallback executable
actually exists to help debugging (plain `execve` doesn't give much
information).

The error code 253 is used to signify that the fallback is not found, but may
mean in the future that it is otherwise invalid if we start being more
specific.

Differential Revision: https://phab.mercurial-scm.org/D12578

# 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)