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a65c86889e
Currently we freeze several modules into the runtime. For each of these modules it is essential to bootstrapping the runtime that they be frozen. Any other stdlib module that we later freeze into the runtime is not essential. We can just as well import from the .py file. This PR lets users explicitly choose which should be used, with the new "-X frozen_modules=[on|off]" CLI flag. The default is "off" for now. https://bugs.python.org/issue45020
266 lines
9.2 KiB
Python
266 lines
9.2 KiB
Python
import contextlib
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import _imp
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import importlib
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import importlib.util
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import os
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import sys
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import unittest
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import warnings
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from .os_helper import unlink
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@contextlib.contextmanager
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def _ignore_deprecated_imports(ignore=True):
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"""Context manager to suppress package and module deprecation
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warnings when importing them.
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If ignore is False, this context manager has no effect.
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"""
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if ignore:
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with warnings.catch_warnings():
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warnings.filterwarnings("ignore", ".+ (module|package)",
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DeprecationWarning)
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yield
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else:
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yield
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def unload(name):
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try:
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del sys.modules[name]
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except KeyError:
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pass
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def forget(modname):
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"""'Forget' a module was ever imported.
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This removes the module from sys.modules and deletes any PEP 3147/488 or
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legacy .pyc files.
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"""
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unload(modname)
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for dirname in sys.path:
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source = os.path.join(dirname, modname + '.py')
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# It doesn't matter if they exist or not, unlink all possible
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# combinations of PEP 3147/488 and legacy pyc files.
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unlink(source + 'c')
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for opt in ('', 1, 2):
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unlink(importlib.util.cache_from_source(source, optimization=opt))
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def make_legacy_pyc(source):
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"""Move a PEP 3147/488 pyc file to its legacy pyc location.
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:param source: The file system path to the source file. The source file
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does not need to exist, however the PEP 3147/488 pyc file must exist.
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:return: The file system path to the legacy pyc file.
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"""
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pyc_file = importlib.util.cache_from_source(source)
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up_one = os.path.dirname(os.path.abspath(source))
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legacy_pyc = os.path.join(up_one, source + 'c')
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os.rename(pyc_file, legacy_pyc)
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return legacy_pyc
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def import_module(name, deprecated=False, *, required_on=()):
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"""Import and return the module to be tested, raising SkipTest if
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it is not available.
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If deprecated is True, any module or package deprecation messages
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will be suppressed. If a module is required on a platform but optional for
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others, set required_on to an iterable of platform prefixes which will be
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compared against sys.platform.
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"""
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with _ignore_deprecated_imports(deprecated):
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try:
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return importlib.import_module(name)
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except ImportError as msg:
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if sys.platform.startswith(tuple(required_on)):
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raise
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raise unittest.SkipTest(str(msg))
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def _save_and_remove_module(name, orig_modules):
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"""Helper function to save and remove a module from sys.modules
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Raise ImportError if the module can't be imported.
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"""
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# try to import the module and raise an error if it can't be imported
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if name not in sys.modules:
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__import__(name)
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del sys.modules[name]
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for modname in list(sys.modules):
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if modname == name or modname.startswith(name + '.'):
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orig_modules[modname] = sys.modules[modname]
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del sys.modules[modname]
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def _save_and_block_module(name, orig_modules):
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"""Helper function to save and block a module in sys.modules
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Return True if the module was in sys.modules, False otherwise.
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"""
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saved = True
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try:
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orig_modules[name] = sys.modules[name]
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except KeyError:
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saved = False
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sys.modules[name] = None
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return saved
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@contextlib.contextmanager
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def frozen_modules(enabled=True):
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"""Force frozen modules to be used (or not).
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This only applies to modules that haven't been imported yet.
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Also, some essential modules will always be imported frozen.
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"""
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_imp._override_frozen_modules_for_tests(1 if enabled else -1)
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try:
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yield
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finally:
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_imp._override_frozen_modules_for_tests(0)
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def import_fresh_module(name, fresh=(), blocked=(), *,
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deprecated=False,
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usefrozen=False,
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):
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"""Import and return a module, deliberately bypassing sys.modules.
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This function imports and returns a fresh copy of the named Python module
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by removing the named module from sys.modules before doing the import.
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Note that unlike reload, the original module is not affected by
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this operation.
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*fresh* is an iterable of additional module names that are also removed
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from the sys.modules cache before doing the import.
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*blocked* is an iterable of module names that are replaced with None
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in the module cache during the import to ensure that attempts to import
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them raise ImportError.
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The named module and any modules named in the *fresh* and *blocked*
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parameters are saved before starting the import and then reinserted into
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sys.modules when the fresh import is complete.
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Module and package deprecation messages are suppressed during this import
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if *deprecated* is True.
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This function will raise ImportError if the named module cannot be
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imported.
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If "usefrozen" is False (the default) then the frozen importer is
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disabled (except for essential modules like importlib._bootstrap).
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"""
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# NOTE: test_heapq, test_json and test_warnings include extra sanity checks
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# to make sure that this utility function is working as expected
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with _ignore_deprecated_imports(deprecated):
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# Keep track of modules saved for later restoration as well
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# as those which just need a blocking entry removed
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orig_modules = {}
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names_to_remove = []
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_save_and_remove_module(name, orig_modules)
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try:
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for fresh_name in fresh:
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_save_and_remove_module(fresh_name, orig_modules)
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for blocked_name in blocked:
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if not _save_and_block_module(blocked_name, orig_modules):
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names_to_remove.append(blocked_name)
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with frozen_modules(usefrozen):
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fresh_module = importlib.import_module(name)
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except ImportError:
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fresh_module = None
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finally:
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for orig_name, module in orig_modules.items():
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sys.modules[orig_name] = module
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for name_to_remove in names_to_remove:
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del sys.modules[name_to_remove]
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return fresh_module
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class CleanImport(object):
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"""Context manager to force import to return a new module reference.
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This is useful for testing module-level behaviours, such as
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the emission of a DeprecationWarning on import.
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Use like this:
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with CleanImport("foo"):
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importlib.import_module("foo") # new reference
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If "usefrozen" is False (the default) then the frozen importer is
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disabled (except for essential modules like importlib._bootstrap).
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"""
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def __init__(self, *module_names, usefrozen=False):
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self.original_modules = sys.modules.copy()
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for module_name in module_names:
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if module_name in sys.modules:
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module = sys.modules[module_name]
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# It is possible that module_name is just an alias for
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# another module (e.g. stub for modules renamed in 3.x).
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# In that case, we also need delete the real module to clear
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# the import cache.
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if module.__name__ != module_name:
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del sys.modules[module.__name__]
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del sys.modules[module_name]
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self._frozen_modules = frozen_modules(usefrozen)
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def __enter__(self):
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self._frozen_modules.__enter__()
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return self
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def __exit__(self, *ignore_exc):
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sys.modules.update(self.original_modules)
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self._frozen_modules.__exit__(*ignore_exc)
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class DirsOnSysPath(object):
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"""Context manager to temporarily add directories to sys.path.
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This makes a copy of sys.path, appends any directories given
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as positional arguments, then reverts sys.path to the copied
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settings when the context ends.
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Note that *all* sys.path modifications in the body of the
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context manager, including replacement of the object,
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will be reverted at the end of the block.
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"""
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def __init__(self, *paths):
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self.original_value = sys.path[:]
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self.original_object = sys.path
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sys.path.extend(paths)
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def __enter__(self):
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return self
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def __exit__(self, *ignore_exc):
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sys.path = self.original_object
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sys.path[:] = self.original_value
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def modules_setup():
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return sys.modules.copy(),
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def modules_cleanup(oldmodules):
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# Encoders/decoders are registered permanently within the internal
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# codec cache. If we destroy the corresponding modules their
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# globals will be set to None which will trip up the cached functions.
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encodings = [(k, v) for k, v in sys.modules.items()
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if k.startswith('encodings.')]
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sys.modules.clear()
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sys.modules.update(encodings)
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# XXX: This kind of problem can affect more than just encodings.
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# In particular extension modules (such as _ssl) don't cope
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# with reloading properly. Really, test modules should be cleaning
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# out the test specific modules they know they added (ala test_runpy)
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# rather than relying on this function (as test_importhooks and test_pkg
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# do currently). Implicitly imported *real* modules should be left alone
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# (see issue 10556).
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sys.modules.update(oldmodules)
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