view hgdemandimport/__init__.py @ 51580:b70628a9aa7e

phases: use revision number in new_heads

All graph operations will be done using revision numbers, so passing nodes only
means they will eventually get converted to revision numbers internally.

As part of an effort to align the code on using revision number we make the
`phases.newheads` function operated on revision number, taking them as input
and using them in returns, instead of the node-id it used to consume and
produce.

This is part of multiple changesets effort to translate more part of the logic,
but is done step by step to facilitate the identification of issue that might
arise in mercurial core and extensions.

To make the change simpler to handle for third party extensions, we also rename
the function, using a more modern form. This will help detecting the different
between the node-id version and the rev-num version.

I also take this as an opportunity to add some comment about possible
performance improvement for the future. They don't matter too much now, but they
are worse exploring in a while.

# 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.


import os
import sys

from . import demandimportpy3 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',
    # setuptools uses this hack to inject it's own distutils at import time
    'setuptools',
    '_distutils_hack.override',
}

_pypy = '__pypy__' in sys.builtin_module_names

if _pypy:
    # _ctypes.pointer is shadowed by "from ... import pointer" (PyPy 5)
    IGNORES.add('_ctypes.pointer')
    # pure Python module on PyPy, must be loaded to raise ModuleNotFoundError
    # on non-Windows platforms
    IGNORES.add('msvcrt')

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()