Mercurial > hg
view hgdemandimport/demandimportpy3.py @ 44261:04a3ae7aba14
chg: force-set LC_CTYPE on server start to actual value from the environment
Python 3.7+ will "coerce" the LC_CTYPE variable in many instances, and this can
cause issues with chg being able to start up. D7550 attempted to fix this, but a
combination of a misreading of the way that python3.7 does the coercion and an
untested state (LC_CTYPE being set to an invalid value) meant that this was
still not quite working.
This change will cause differences between chg and hg: hg will have the LC_CTYPE
environment variable coerced, while chg will not. This is unlikely to cause any
detectable behavior differences in what Mercurial itself outputs, but it does
have two known effects:
- When using hg, the coerced LC_CTYPE will be passed to subprocesses, even
non-python ones. Using chg will remove the coercion, and this will not
happen. This is arguably more correct behavior on chg's part.
- On macOS, if you set your region to Brazil but your language to English,
this isn't representable in locale strings, so macOS sets LC_CTYPE=UTF-8. If
this value is passed along when ssh'ing to a non-macOS machine, some
functions (such as locale.setlocale()) may raise an exception due to an
unsupported locale setting. This is most easily encountered when doing an
interactive commit/split/etc. when using ui.interface=curses.
Differential Revision: https://phab.mercurial-scm.org/D8039
author | Kyle Lippincott <spectral@google.com> |
---|---|
date | Wed, 29 Jan 2020 13:39:50 -0800 |
parents | f81c17ec303c |
children | a6e12d477595 |
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# demandimportpy3 - 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. """Lazy loading for Python 3.6 and above. This uses the new importlib finder/loader functionality available in Python 3.5 and up. The code reuses most of the mechanics implemented inside importlib.util, but with a few additions: * Allow excluding certain modules from lazy imports. * Expose an interface that's substantially the same as demandimport for Python 2. This also has some limitations compared to the Python 2 implementation: * Much of the logic is per-package, not per-module, so any packages loaded before demandimport is enabled will not be lazily imported in the future. In practice, we only expect builtins to be loaded before demandimport is enabled. """ # This line is unnecessary, but it satisfies test-check-py3-compat.t. from __future__ import absolute_import import contextlib import importlib.util import sys from . import tracing _deactivated = False # Python 3.5's LazyLoader doesn't work for some reason. # https://bugs.python.org/issue26186 is a known issue with extension # importing. But it appears to not have a meaningful effect with # Mercurial. _supported = sys.version_info[0:2] >= (3, 6) class _lazyloaderex(importlib.util.LazyLoader): """This is a LazyLoader except it also follows the _deactivated global and the ignore list. """ def exec_module(self, module): """Make the module load lazily.""" with tracing.log('demandimport %s', module): if _deactivated or module.__name__ in ignores: self.loader.exec_module(module) else: super().exec_module(module) class LazyFinder(object): """A wrapper around a ``MetaPathFinder`` that makes loaders lazy. ``sys.meta_path`` finders have their ``find_spec()`` called to locate a module. This returns a ``ModuleSpec`` if found or ``None``. The ``ModuleSpec`` has a ``loader`` attribute, which is called to actually load a module. Our class wraps an existing finder and overloads its ``find_spec()`` to replace the ``loader`` with our lazy loader proxy. We have to use __getattribute__ to proxy the instance because some meta path finders don't support monkeypatching. """ __slots__ = ("_finder",) def __init__(self, finder): object.__setattr__(self, "_finder", finder) def __repr__(self): return "<LazyFinder for %r>" % object.__getattribute__(self, "_finder") # __bool__ is canonical Python 3. But check-code insists on __nonzero__ being # defined via `def`. def __nonzero__(self): return bool(object.__getattribute__(self, "_finder")) __bool__ = __nonzero__ def __getattribute__(self, name): if name in ("_finder", "find_spec"): return object.__getattribute__(self, name) return getattr(object.__getattribute__(self, "_finder"), name) def __delattr__(self, name): return delattr(object.__getattribute__(self, "_finder")) def __setattr__(self, name, value): return setattr(object.__getattribute__(self, "_finder"), name, value) def find_spec(self, *args, **kwargs): finder = object.__getattribute__(self, "_finder") spec = finder.find_spec(*args, **kwargs) # Lazy loader requires exec_module(). if ( spec is not None and spec.loader is not None and getattr(spec.loader, "exec_module") ): spec.loader = _lazyloaderex(spec.loader) return spec ignores = set() def init(ignoreset): global ignores ignores = ignoreset def isenabled(): return not _deactivated and any( isinstance(finder, LazyFinder) for finder in sys.meta_path ) def disable(): new_finders = [] for finder in sys.meta_path: new_finders.append( finder._finder if isinstance(finder, LazyFinder) else finder ) sys.meta_path[:] = new_finders def enable(): if not _supported: return new_finders = [] for finder in sys.meta_path: new_finders.append( LazyFinder(finder) if not isinstance(finder, LazyFinder) else finder ) sys.meta_path[:] = new_finders @contextlib.contextmanager def deactivated(): # This implementation is a bit different from Python 2's. Python 3 # maintains a per-package finder cache in sys.path_importer_cache (see # PEP 302). This means that we can't just call disable + enable. # If we do that, in situations like: # # demandimport.enable() # ... # from foo.bar import mod1 # with demandimport.deactivated(): # from foo.bar import mod2 # # mod2 will be imported lazily. (The converse also holds -- whatever finder # first gets cached will be used.) # # Instead, have a global flag the LazyLoader can use. global _deactivated demandenabled = isenabled() if demandenabled: _deactivated = True try: yield finally: if demandenabled: _deactivated = False