hgdemandimport/tracing.py

inno: stop shipping pywin32

Ancient versions of Mercurial relied on pywin32 and I suspect
that's why we have this dependency.

We also ship the "keyring" package, which has a dependency
on "pywin32-ctypes" (providing the "win32ctypes" package).
This is a stripped down version of pywin32 that doesn't have
as many dependencies.

Since we don't have a dependency on pywin32 and since pywin32
is a bit annoying to package, let's get rid of it.

With this change, py2exe no longers picks up DLL dependencies
on various UCRT DLLs (because we no longer have a .pyd file
beloning to pywin32 which was pulling them in). So, we were
able to remove code in support of the UCRT DLLs.

.. bc::

   The Windows Inno installers no longer ship the pywin32 package.

   This package was being bundled for historical reasons. Mercurial
   stopped using pywin32 several years ago and the disappearance
   of this package should not have any meaningful impact.

Differential Revision: https://phab.mercurial-scm.org/D6067

# Support code for event tracing in Mercurial. Lives in demandimport
# so it can also be used in demandimport.
#
# Copyright 2018 Google LLC.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import

import contextlib
import os

_pipe = None
_checked = False

@contextlib.contextmanager
def log(whencefmt, *whenceargs):
    global _pipe, _session, _checked
    if _pipe is None:
        if _checked:
            yield
            return
        _checked = True
        if 'HGCATAPULTSERVERPIPE' not in os.environ:
            yield
            return
        _pipe = open(os.environ['HGCATAPULTSERVERPIPE'], 'w', 1)
        _session = os.environ.get('HGCATAPULTSESSION', 'none')
    whence = whencefmt % whenceargs
    try:
        # Both writes to the pipe are wrapped in try/except to ignore
        # errors, as we can see mysterious errors in here if the pager
        # is active. Presumably other conditions could trigger
        # problems too.
        try:
            _pipe.write('START %s %s\n' % (_session, whence))
        except IOError:
            pass
        yield
    finally:
        try:
            _pipe.write('END %s %s\n' % (_session, whence))
        except IOError:
            pass