view contrib/memory.py @ 47941:5b9de38a0356 stable

narrow: fix commits of empty files

The problem is that when committing a new file with empty contents (or
in general empty file with filelog p1 = -1), hg commit with narrow
doesn't create a filelog revision at all, which causes failures in
further commands.

The problem seems to be that:
- hg thinks that instead of creating a new filelog revision, it can
  use the filelog's p1 (the nullrev)
- because it thinks the file contents is the same in that revision and
  in p1
- because `narrowfilelog.cmp(nullrev, b'')` is True (unlike with
  `filelog.cmp`)

It's not clear to me which `cmp` behaves better. But I think it makes
sense to change the commit code to not to "reuse" the null rev when
adding an empty file with filelog p1 == filelog p2 == -1. This is
consistent with never writing the null rev in the manifest, which `hg
verify` claims is an invariant:

```
inside/c@4: manifest refers to unknown revision 000000000000
```

Differential Revision: https://phab.mercurial-scm.org/D11400

# 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)