Mercurial > hg
view hgdemandimport/__init__.py @ 38162:bdf344aea0ee
extensions: peek command table of disabled extensions without importing
With chg where demandimport disabled, and if disk cache not warm, it took
more than 5 seconds to get "unknown command" error when you typo a command
name. This is horrible UX.
The new implementation is less accurate than the original one as Python
can do anything at import time and cmdtable may be imported from another
module, but I think it's good enough.
Note that the new implementation has to parse .py files, which is slightly
slower than executing .pyc if demandimport is enabled.
author | Yuya Nishihara <yuya@tcha.org> |
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date | Thu, 03 May 2018 18:38:02 +0900 |
parents | 670eb4fa1b86 |
children | 2372284d9457 |
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# 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__', '_ssl', # conditional imports in the stdlib, issue1964 '_sre', # issue4920 'rfc822', 'mimetools', 'sqlalchemy.events', # has import-time side effects (issue5085) # setuptools 8 expects this module to explode early when not on windows 'distutils.msvc9compiler', '__builtin__', 'builtins', 'urwid.command_map', # for pudb } _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()