hg

hg: wrap the highest layer in the `hg` script possible in trace event

This should help us have a better idea of what "interpreter startup
costs" look like. This does omit the HGUNICODEPEDANTRY block and the
LIBDIR dancing to set up sys.path, but the former is usually off and
the latter is unavoidable and should be very fast. If we get worried
about those cases we can consider open-coding the tracing logic here.

Differential Revision: https://phab.mercurial-scm.org/D4346

#!/usr/bin/env python
#
# mercurial - scalable distributed SCM
#
# Copyright 2005-2007 Matt Mackall <[e-mail]>
#
# 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 os
import sys

if os.environ.get('HGUNICODEPEDANTRY', False):
    try:
        reload(sys)
        sys.setdefaultencoding("undefined")
    except NameError:
        pass

libdir = '@LIBDIR@'

if libdir != '@' 'LIBDIR' '@':
    if not os.path.isabs(libdir):
        libdir = os.path.join(os.path.dirname(os.path.realpath(__file__)),
                              libdir)
        libdir = os.path.abspath(libdir)
    sys.path.insert(0, libdir)

from hgdemandimport import tracing
with tracing.log('hg script'):
    # enable importing on demand to reduce startup time
    try:
        if sys.version_info[0] < 3 or sys.version_info >= (3, 6):
            import hgdemandimport; hgdemandimport.enable()
    except ImportError:
        sys.stderr.write("abort: couldn't find mercurial libraries in [%s]\n" %
                         ' '.join(sys.path))
        sys.stderr.write("(check your install and PYTHONPATH)\n")
        sys.exit(-1)

    from mercurial import dispatch
    dispatch.run()