mirror of https://github.com/pulumi/pulumi.git
343 lines
11 KiB
Python
343 lines
11 KiB
Python
# Copyright 2016-2020, Pulumi Corporation.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from contextvars import ContextVar
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import importlib
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import importlib.abc
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import sys
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import types
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import typing
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# Empty function definitions.
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def _empty(): ...
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def _empty_doc():
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"""Empty function docstring."""
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def _empty_lambda():
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return None
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def _empty_lambda_doc():
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return None
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_empty_lambda_doc.__doc__ = """Empty lambda docstring."""
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def _consts(fn: typing.Callable) -> tuple:
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"""
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Returns a tuple of the function's constants excluding the docstring.
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"""
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return tuple(x for x in fn.__code__.co_consts if x != fn.__doc__)
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# Precompute constants for each of the empty functions.
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_consts_empty = _consts(_empty)
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_consts_empty_doc = _consts(_empty_doc)
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_consts_empty_lambda = _consts(_empty_lambda)
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_consts_empty_lambda_doc = _consts(_empty_lambda_doc)
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def is_empty_function(fn: typing.Callable) -> bool:
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"""
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Returns true if the function is empty.
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"""
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consts = _consts(fn)
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return (
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(fn.__code__.co_code == _empty.__code__.co_code and consts == _consts_empty)
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or (
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fn.__code__.co_code == _empty_doc.__code__.co_code
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and consts == _consts_empty_doc
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)
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or (
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fn.__code__.co_code == _empty_lambda.__code__.co_code
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and consts == _consts_empty_lambda
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)
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or (
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fn.__code__.co_code == _empty_lambda_doc.__code__.co_code
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and consts == _consts_empty_lambda_doc
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)
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)
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def lazy_import(fullname):
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"""Defers module import until first attribute access. For example:
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import a.b.c as x
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Becomes:
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x = lazy_import('a.b.c')
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The code started from the official Python example:
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https://github.com/python/cpython/blob/master/Doc/library/importlib.rst#implementing-lazy-imports
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This example is extended by early returns to support import cycles
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and registration of sub-modules as attributes.
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"""
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# Return early if already registered; this supports import cycles.
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m = sys.modules.get(fullname, None)
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if m is not None:
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return m
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spec = importlib.util.find_spec(fullname)
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# Return early if find_spec has recursively called lazy_import
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# again and pre-populated the sys.modules slot; an example of this
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# is covered by test_lazy_import.
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m = sys.modules.get(fullname, None)
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if m is not None:
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return m
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loader = _LazyLoader(spec.loader)
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spec.loader = loader
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module = importlib.util.module_from_spec(spec)
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# Return early rather than overwriting the sys.modules slot.
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m = sys.modules.get(fullname, None)
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if m is not None:
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return m
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sys.modules[fullname] = module
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loader.exec_module(module)
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return module
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def contextproperty(fn=None, *, default: typing.Optional[typing.Any] = None):
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"""Decorator interface for ContextProperty
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This gives a @property-like interface into ContextProperty:
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.. testsetup::
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class Foo:
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@contextproperty(default="bar")
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def my_attribute(): ...
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>>> class Foo:
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... @contextproperty(default="bar")
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... def my_attribute(): ...
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>>> Foo().my_attribute
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'bar'
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"""
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def inner(func: typing.Callable):
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new_property = ContextProperty(
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name=func.__qualname__, doc=func.__doc__, default=default
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)
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inner.__doc__ = new_property.__doc__
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return new_property
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if fn is None:
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return inner
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return inner(fn)
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# We don't currently use doctest anywhere, but they can be helpful
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# usage guides - we double-declare Foo in this case because the testsetup directive
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# is hidden from docstrings
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class ContextProperty:
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"""Property-like interface for ContextVars
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This class is intended to wrap attribute access in class instances in a property-like interface
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while also ensuring the data being stored does not leak between contexts.
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The preferred method for using this class is via the @contextproperty decorator, though it
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can also be used directly:
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.. testsetup::
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class Foo:
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my_attribute = ContextProperty(name="foo", default="bar")
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>>> class Foo:
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... my_attribute = ContextProperty(name="foo", default="bar")
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>>> Foo().my_attribute
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'bar'
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"""
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def __init__(
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self,
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*_,
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name: str,
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doc: typing.Optional[str] = None,
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default: typing.Optional[typing.Any] = None,
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):
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"""
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:param str name: The name assigned to both the property and also passed to the underlying ContextVar
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:param str doc: Docstring to assign to this property
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:param Any default: Default value to be passed to the underlying ContextVar
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"""
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if not doc:
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doc = self.fget.__doc__
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self.__doc__ = doc
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self._name = name
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self.__default = default
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self._data: ContextVar = ContextVar(name, default=default)
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def __repr__(self):
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return f"<class {type(self).__qualname__}[name={self._data.name.__repr__()} default={self.__default.__repr__()}] value: {self._data.get().__repr__()}>"
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def fget(self, *_):
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return self._data.get(self.__default)
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def fset(self, v: typing.Any, *_):
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if self._data.get() is None:
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self.__default = v
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return self._data.set(v)
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def fdel(self, *_):
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return self._data.reset()
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def __set__(self, _, v: typing.Any):
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return self.fset(v)
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def __get__(self, obj: typing.Optional[typing.Any], _):
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if obj is None or isinstance(self.fget(), dict):
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return self
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return self.fget()
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def __delete__(self, *_):
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self.fdel()
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def __setitem__(self, key, value):
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data = self.fget()
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if not isinstance(data, dict):
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raise TypeError("Can't set key values on non-dict variables.")
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data[key] = value
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return self.fset(data)
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def __dict__(self):
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if not isinstance(self.fget(), dict):
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raise TypeError(f"{self} is not a dictionary")
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return self.fget()
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def __getitem__(self, key):
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return self.fget()[key]
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def __contains__(self, element):
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return element in self.fget()
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def getter(self, fget):
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prop = type(self)(fget, self.fset, self.fdel, name=self._name, doc=self.__doc__)
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return prop
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def setter(self, fset):
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prop = type(self)(self.fget, fset, self.fdel, name=self._name, doc=self.__doc__)
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return prop
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def deleter(self, fdel):
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prop = type(self)(self.fget, self.fset, fdel, name=self._name, doc=self.__doc__)
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return prop
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# Python 3.11.9 and 3.12.3 introduced a regression that broke lazy loading of
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# `config` modules in generated provider SDKs.
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# See https://github.com/python/cpython/pull/117185#issuecomment-2060851286.
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# To workaround, use a private copy of _LazyModule and LazyLoader (renamed
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# _LazyLoader) from the Python stdlib, which don't have the regression,
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# as suggested by the Python maintainers.
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class _LazyModule(types.ModuleType):
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"""A subclass of the module type which triggers loading upon attribute access."""
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def __getattribute__(self, attr):
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"""Trigger the load of the module and return the attribute."""
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# All module metadata must be garnered from __spec__ in order to avoid
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# using mutated values.
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# Stop triggering this method.
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self.__class__ = types.ModuleType
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# Get the original name to make sure no object substitution occurred
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# in sys.modules.
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original_name = self.__spec__.name
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# Figure out exactly what attributes were mutated between the creation
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# of the module and now.
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attrs_then = self.__spec__.loader_state["__dict__"]
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attrs_now = self.__dict__
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attrs_updated = {}
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for key, value in attrs_now.items():
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# Code that set the attribute may have kept a reference to the
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# assigned object, making identity more important than equality.
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if key not in attrs_then:
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attrs_updated[key] = value
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elif id(attrs_now[key]) != id(attrs_then[key]):
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attrs_updated[key] = value
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self.__spec__.loader.exec_module(self)
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# If exec_module() was used directly there is no guarantee the module
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# object was put into sys.modules.
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if original_name in sys.modules:
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if id(self) != id(sys.modules[original_name]):
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raise ValueError(
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f"module object for {original_name!r} "
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"substituted in sys.modules during a lazy "
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"load"
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)
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# Update after loading since that's what would happen in an eager
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# loading situation.
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self.__dict__.update(attrs_updated)
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return getattr(self, attr)
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def __delattr__(self, attr):
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"""Trigger the load and then perform the deletion."""
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# To trigger the load and raise an exception if the attribute
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# doesn't exist.
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self.__getattribute__(attr)
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delattr(self, attr)
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class _LazyLoader(importlib.abc.Loader):
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"""A loader that creates a module which defers loading until attribute access."""
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@staticmethod
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def __check_eager_loader(loader):
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if not hasattr(loader, "exec_module"):
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raise TypeError("loader must define exec_module()")
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@classmethod
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def factory(cls, loader):
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"""Construct a callable which returns the eager loader made lazy."""
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cls.__check_eager_loader(loader)
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return lambda *args, **kwargs: cls(loader(*args, **kwargs))
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def __init__(self, loader):
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self.__check_eager_loader(loader)
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self.loader = loader
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def create_module(self, spec):
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return self.loader.create_module(spec)
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def exec_module(self, module):
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"""Make the module load lazily."""
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module.__spec__.loader = self.loader
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module.__loader__ = self.loader
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# Don't need to worry about deep-copying as trying to set an attribute
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# on an object would have triggered the load,
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# e.g. ``module.__spec__.loader = None`` would trigger a load from
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# trying to access module.__spec__.
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loader_state = {}
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loader_state["__dict__"] = module.__dict__.copy()
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loader_state["__class__"] = module.__class__
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module.__spec__.loader_state = loader_state
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module.__class__ = _LazyModule
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