view hgdemandimport/__init__.py @ 46546:075b2499e3d6

test-copies: add test chaining multiple merge

Right now, the copy tracing logic take the right decision for merges, but it
does not keep track of the right information about these decision and can fall
into later traps. We start with highlighting this possibility by adding new
tests, and we will fix them later.

Check the inline test documentation for details.

Differential Revision: https://phab.mercurial-scm.org/D9611

# hgdemandimport - global demand-loading of modules for Mercurial
#
# Copyright 2017 Facebook Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

'''demandimport - automatic demand-loading of modules'''

# This is in a separate package from mercurial because in Python 3,
# demand loading is per-package. Keeping demandimport in the mercurial package
# would disable demand loading for any modules in mercurial.

from __future__ import absolute_import

import os
import sys

if sys.version_info[0] >= 3:
    from . import demandimportpy3 as demandimport
else:
    from . import demandimportpy2 as demandimport

# Full module names which can't be lazy imported.
# Extensions can add to this set.
IGNORES = {
    '__future__',
    '_hashlib',
    # ImportError during pkg_resources/__init__.py:fixup_namespace_package
    '_imp',
    '_xmlplus',
    'fcntl',
    'nt',  # pathlib2 tests the existence of built-in 'nt' module
    'win32com.gen_py',
    'win32com.shell',  # 'appdirs' tries to import win32com.shell
    '_winreg',  # 2.7 mimetypes needs immediate ImportError
    'pythoncom',
    # imported by tarfile, not available under Windows
    'pwd',
    'grp',
    # imported by profile, itself imported by hotshot.stats,
    # not available under Windows
    'resource',
    # this trips up many extension authors
    'gtk',
    # setuptools' pkg_resources.py expects "from __main__ import x" to
    # raise ImportError if x not defined
    '__main__',
    '_ast',  # https://bugs.python.org/issue41631
    '_ssl',  # conditional imports in the stdlib, issue1964
    '_sre',  # issue4920
    'rfc822',
    'mimetools',
    'sqlalchemy.events',  # has import-time side effects (issue5085)
    'sqlalchemy.dialects',  # similar problems as above
    # setuptools 8 expects this module to explode early when not on windows
    'distutils.msvc9compiler',
    '__builtin__',
    'builtins',
    'urwid.command_map',  # for pudb
    'lzma',
}

_pypy = '__pypy__' in sys.builtin_module_names

if _pypy:
    # _ctypes.pointer is shadowed by "from ... import pointer" (PyPy 5)
    IGNORES.add('_ctypes.pointer')

demandimport.init(IGNORES)

# Re-export.
isenabled = demandimport.isenabled
disable = demandimport.disable
deactivated = demandimport.deactivated


def enable():
    # chg pre-imports modules so do not enable demandimport for it
    if (
        'CHGINTERNALMARK' not in os.environ
        and os.environ.get('HGDEMANDIMPORT') != 'disable'
    ):
        demandimport.enable()