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authorJames Taylor <user234683@users.noreply.github.com>2019-09-06 16:31:13 -0700
committerJames Taylor <user234683@users.noreply.github.com>2019-09-06 16:31:13 -0700
commit3d57e14df7ba5f14a634295caf3b2e60da50bfe2 (patch)
tree4903bcb79a49ad714a1a9129765b9545405c9978 /python/gevent/local.py
parentac32b24b2a011292b704a3f27e8fd08a7ae9424b (diff)
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Remove windows python distribution from repo and add requirements.txt
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-# cython: auto_pickle=False,embedsignature=True,always_allow_keywords=False
-"""
-Greenlet-local objects.
-
-This module is based on `_threading_local.py`__ from the standard
-library of Python 3.4.
-
-__ https://github.com/python/cpython/blob/3.4/Lib/_threading_local.py
-
-Greenlet-local objects support the management of greenlet-local data.
-If you have data that you want to be local to a greenlet, simply create
-a greenlet-local object and use its attributes:
-
- >>> mydata = local()
- >>> mydata.number = 42
- >>> mydata.number
- 42
-
-You can also access the local-object's dictionary:
-
- >>> mydata.__dict__
- {'number': 42}
- >>> mydata.__dict__.setdefault('widgets', [])
- []
- >>> mydata.widgets
- []
-
-What's important about greenlet-local objects is that their data are
-local to a greenlet. If we access the data in a different greenlet:
-
- >>> log = []
- >>> def f():
- ... items = list(mydata.__dict__.items())
- ... items.sort()
- ... log.append(items)
- ... mydata.number = 11
- ... log.append(mydata.number)
- >>> greenlet = gevent.spawn(f)
- >>> greenlet.join()
- >>> log
- [[], 11]
-
-we get different data. Furthermore, changes made in the other greenlet
-don't affect data seen in this greenlet:
-
- >>> mydata.number
- 42
-
-Of course, values you get from a local object, including a __dict__
-attribute, are for whatever greenlet was current at the time the
-attribute was read. For that reason, you generally don't want to save
-these values across greenlets, as they apply only to the greenlet they
-came from.
-
-You can create custom local objects by subclassing the local class:
-
- >>> class MyLocal(local):
- ... number = 2
- ... initialized = False
- ... def __init__(self, **kw):
- ... if self.initialized:
- ... raise SystemError('__init__ called too many times')
- ... self.initialized = True
- ... self.__dict__.update(kw)
- ... def squared(self):
- ... return self.number ** 2
-
-This can be useful to support default values, methods and
-initialization. Note that if you define an __init__ method, it will be
-called each time the local object is used in a separate greenlet. This
-is necessary to initialize each greenlet's dictionary.
-
-Now if we create a local object:
-
- >>> mydata = MyLocal(color='red')
-
-Now we have a default number:
-
- >>> mydata.number
- 2
-
-an initial color:
-
- >>> mydata.color
- 'red'
- >>> del mydata.color
-
-And a method that operates on the data:
-
- >>> mydata.squared()
- 4
-
-As before, we can access the data in a separate greenlet:
-
- >>> log = []
- >>> greenlet = gevent.spawn(f)
- >>> greenlet.join()
- >>> log
- [[('color', 'red'), ('initialized', True)], 11]
-
-without affecting this greenlet's data:
-
- >>> mydata.number
- 2
- >>> mydata.color
- Traceback (most recent call last):
- ...
- AttributeError: 'MyLocal' object has no attribute 'color'
-
-Note that subclasses can define slots, but they are not greenlet
-local. They are shared across greenlets::
-
- >>> class MyLocal(local):
- ... __slots__ = 'number'
-
- >>> mydata = MyLocal()
- >>> mydata.number = 42
- >>> mydata.color = 'red'
-
-So, the separate greenlet:
-
- >>> greenlet = gevent.spawn(f)
- >>> greenlet.join()
-
-affects what we see:
-
- >>> mydata.number
- 11
-
->>> del mydata
-
-.. versionchanged:: 1.1a2
- Update the implementation to match Python 3.4 instead of Python 2.5.
- This results in locals being eligible for garbage collection as soon
- as their greenlet exits.
-
-.. versionchanged:: 1.2.3
- Use a weak-reference to clear the greenlet link we establish in case
- the local object dies before the greenlet does.
-
-.. versionchanged:: 1.3a1
- Implement the methods for attribute access directly, handling
- descriptors directly here. This allows removing the use of a lock
- and facilitates greatly improved performance.
-
-.. versionchanged:: 1.3a1
- The ``__init__`` method of subclasses of ``local`` is no longer
- called with a lock held. CPython does not use such a lock in its
- native implementation. This could potentially show as a difference
- if code that uses multiple dependent attributes in ``__slots__``
- (which are shared across all greenlets) switches during ``__init__``.
-
-"""
-from __future__ import print_function
-
-from copy import copy
-from weakref import ref
-
-
-locals()['getcurrent'] = __import__('greenlet').getcurrent
-locals()['greenlet_init'] = lambda: None
-
-__all__ = [
- "local",
-]
-
-# The key used in the Thread objects' attribute dicts.
-# We keep it a string for speed but make it unlikely to clash with
-# a "real" attribute.
-key_prefix = '_gevent_local_localimpl_'
-
-# The overall structure is as follows:
-# For each local() object:
-# greenlet.__dict__[key_prefix + str(id(local))]
-# => _localimpl.dicts[id(greenlet)] => (ref(greenlet), {})
-
-# That final tuple is actually a localimpl_dict_entry object.
-
-def all_local_dicts_for_greenlet(greenlet):
- """
- Internal debug helper for getting the local values associated
- with a greenlet. This is subject to change or removal at any time.
-
- :return: A list of ((type, id), {}) pairs, where the first element
- is the type and id of the local object and the second object is its
- instance dictionary, as seen from this greenlet.
-
- .. versionadded:: 1.3a2
- """
-
- result = []
- id_greenlet = id(greenlet)
- greenlet_dict = greenlet.__dict__
- for k, v in greenlet_dict.items():
- if not k.startswith(key_prefix):
- continue
- local_impl = v()
- if local_impl is None:
- continue
- entry = local_impl.dicts.get(id_greenlet)
- if entry is None:
- # Not yet used in this greenlet.
- continue
- assert entry.wrgreenlet() is greenlet
- result.append((local_impl.localtypeid, entry.localdict))
-
- return result
-
-
-class _wrefdict(dict):
- """A dict that can be weak referenced"""
-
-class _greenlet_deleted(object):
- """
- A weakref callback for when the greenlet
- is deleted.
-
- If the greenlet is a `gevent.greenlet.Greenlet` and
- supplies ``rawlink``, that will be used instead of a
- weakref.
- """
- __slots__ = ('idt', 'wrdicts')
-
- def __init__(self, idt, wrdicts):
- self.idt = idt
- self.wrdicts = wrdicts
-
- def __call__(self, _unused):
- dicts = self.wrdicts()
- if dicts:
- dicts.pop(self.idt, None)
-
-class _local_deleted(object):
- __slots__ = ('key', 'wrthread', 'greenlet_deleted')
-
- def __init__(self, key, wrthread, greenlet_deleted):
- self.key = key
- self.wrthread = wrthread
- self.greenlet_deleted = greenlet_deleted
-
- def __call__(self, _unused):
- thread = self.wrthread()
- if thread is not None:
- try:
- unlink = thread.unlink
- except AttributeError:
- pass
- else:
- unlink(self.greenlet_deleted)
- del thread.__dict__[self.key]
-
-class _localimpl(object):
- """A class managing thread-local dicts"""
- __slots__ = ('key', 'dicts',
- 'localargs', 'localkwargs',
- 'localtypeid',
- '__weakref__',)
-
- def __init__(self, args, kwargs, local_type, id_local):
- self.key = key_prefix + str(id(self))
- # { id(greenlet) -> _localimpl_dict_entry(ref(greenlet), greenlet-local dict) }
- self.dicts = _wrefdict()
- self.localargs = args
- self.localkwargs = kwargs
- self.localtypeid = local_type, id_local
-
- # We need to create the thread dict in anticipation of
- # __init__ being called, to make sure we don't call it
- # again ourselves. MUST do this before setting any attributes.
- greenlet = getcurrent() # pylint:disable=undefined-variable
- _localimpl_create_dict(self, greenlet, id(greenlet))
-
-class _localimpl_dict_entry(object):
- """
- The object that goes in the ``dicts`` of ``_localimpl``
- object for each thread.
- """
- # This is a class, not just a tuple, so that cython can optimize
- # attribute access
- __slots__ = ('wrgreenlet', 'localdict')
-
- def __init__(self, wrgreenlet, localdict):
- self.wrgreenlet = wrgreenlet
- self.localdict = localdict
-
-# We use functions instead of methods so that they can be cdef'd in
-# local.pxd; if they were cdef'd as methods, they would cause
-# the creation of a pointer and a vtable. This happens
-# even if we declare the class @cython.final. functions thus save memory overhead
-# (but not pointer chasing overhead; the vtable isn't used when we declare
-# the class final).
-
-
-def _localimpl_create_dict(self, greenlet, id_greenlet):
- """Create a new dict for the current thread, and return it."""
- localdict = {}
- key = self.key
-
- wrdicts = ref(self.dicts)
-
- # When the greenlet is deleted, remove the local dict.
- # Note that this is suboptimal if the greenlet object gets
- # caught in a reference loop. We would like to be called
- # as soon as the OS-level greenlet ends instead.
-
- # If we are working with a gevent.greenlet.Greenlet, we
- # can pro-actively clear out with a link, avoiding the
- # issue described above. Use rawlink to avoid spawning any
- # more greenlets.
- greenlet_deleted = _greenlet_deleted(id_greenlet, wrdicts)
-
- rawlink = getattr(greenlet, 'rawlink', None)
- if rawlink is not None:
- rawlink(greenlet_deleted)
- wrthread = ref(greenlet)
- else:
- wrthread = ref(greenlet, greenlet_deleted)
-
-
- # When the localimpl is deleted, remove the thread attribute.
- local_deleted = _local_deleted(key, wrthread, greenlet_deleted)
-
-
- wrlocal = ref(self, local_deleted)
- greenlet.__dict__[key] = wrlocal
-
- self.dicts[id_greenlet] = _localimpl_dict_entry(wrthread, localdict)
- return localdict
-
-
-_marker = object()
-
-def _local_get_dict(self):
- impl = self._local__impl
- # Cython can optimize dict[], but not dict.get()
- greenlet = getcurrent() # pylint:disable=undefined-variable
- idg = id(greenlet)
- try:
- entry = impl.dicts[idg]
- dct = entry.localdict
- except KeyError:
- dct = _localimpl_create_dict(impl, greenlet, idg)
- self.__init__(*impl.localargs, **impl.localkwargs)
- return dct
-
-def _init():
- greenlet_init() # pylint:disable=undefined-variable
-
-_local_attrs = {
- '_local__impl',
- '_local_type_get_descriptors',
- '_local_type_set_or_del_descriptors',
- '_local_type_del_descriptors',
- '_local_type_set_descriptors',
- '_local_type',
- '_local_type_vars',
- '__class__',
- '__cinit__',
-}
-
-class local(object):
- """
- An object whose attributes are greenlet-local.
- """
- __slots__ = tuple(_local_attrs - {'__class__', '__cinit__'})
-
- def __cinit__(self, *args, **kw):
- if args or kw:
- if type(self).__init__ == object.__init__:
- raise TypeError("Initialization arguments are not supported", args, kw)
- impl = _localimpl(args, kw, type(self), id(self))
- # pylint:disable=attribute-defined-outside-init
- self._local__impl = impl
- get, dels, sets_or_dels, sets = _local_find_descriptors(self)
- self._local_type_get_descriptors = get
- self._local_type_set_or_del_descriptors = sets_or_dels
- self._local_type_del_descriptors = dels
- self._local_type_set_descriptors = sets
- self._local_type = type(self)
- self._local_type_vars = set(dir(self._local_type))
-
- def __getattribute__(self, name): # pylint:disable=too-many-return-statements
- if name in _local_attrs:
- # The _local__impl, __cinit__, etc, won't be hit by the
- # Cython version, if we've done things right. If we haven't,
- # they will be, and this will produce an error.
- return object.__getattribute__(self, name)
-
- dct = _local_get_dict(self)
-
- if name == '__dict__':
- return dct
- # If there's no possible way we can switch, because this
- # attribute is *not* found in the class where it might be a
- # data descriptor (property), and it *is* in the dict
- # then we don't need to swizzle the dict and take the lock.
-
- # We don't have to worry about people overriding __getattribute__
- # because if they did, the dict-swizzling would only last as
- # long as we were in here anyway.
- # Similarly, a __getattr__ will still be called by _oga() if needed
- # if it's not in the dict.
-
- # Optimization: If we're not subclassed, then
- # there can be no descriptors except for methods, which will
- # never need to use __dict__.
- if self._local_type is local:
- return dct[name] if name in dct else object.__getattribute__(self, name)
-
- # NOTE: If this is a descriptor, this will invoke its __get__.
- # A broken descriptor that doesn't return itself when called with
- # a None for the instance argument could mess us up here.
- # But this is faster than a loop over mro() checking each class __dict__
- # manually.
- if name in dct:
- if name not in self._local_type_vars:
- # If there is a dict value, and nothing in the type,
- # it can't possibly be a descriptor, so it is just returned.
- return dct[name]
-
- # It's in the type *and* in the dict. If the type value is
- # a data descriptor (defines __get__ *and* either __set__ or
- # __delete__), then the type wins. If it's a non-data descriptor
- # (defines just __get__), then the instance wins. If it's not a
- # descriptor at all (doesn't have __get__), the instance wins.
- # NOTE that the docs for descriptors say that these methods must be
- # defined on the *class* of the object in the type.
- if name not in self._local_type_get_descriptors:
- # Entirely not a descriptor. Instance wins.
- return dct[name]
- if name in self._local_type_set_or_del_descriptors:
- # A data descriptor.
- # arbitrary code execution while these run. If they touch self again,
- # they'll call back into us and we'll repeat the dance.
- type_attr = getattr(self._local_type, name)
- return type(type_attr).__get__(type_attr, self, self._local_type)
- # Last case is a non-data descriptor. Instance wins.
- return dct[name]
-
- if name in self._local_type_vars:
- # Not in the dictionary, but is found in the type. It could be
- # a non-data descriptor still. Some descriptors, like @staticmethod,
- # return objects (functions, in this case), that are *themselves*
- # descriptors, which when invoked, again, would do the wrong thing.
- # So we can't rely on getattr() on the type for them, we have to
- # look through the MRO dicts ourself.
- if name not in self._local_type_get_descriptors:
- # Not a descriptor, can't execute code. So all we need is
- # the return value of getattr() on our type.
- return getattr(self._local_type, name)
-
- for base in self._local_type.mro():
- bd = base.__dict__
- if name in bd:
- attr_on_type = bd[name]
- result = type(attr_on_type).__get__(attr_on_type, self, self._local_type)
- return result
-
- # It wasn't in the dict and it wasn't in the type.
- # So the next step is to invoke type(self)__getattr__, if it
- # exists, otherwise raise an AttributeError.
- # we will invoke type(self).__getattr__ or raise an attribute error.
- if hasattr(self._local_type, '__getattr__'):
- return self._local_type.__getattr__(self, name)
- raise AttributeError("%r object has no attribute '%s'"
- % (self._local_type.__name__, name))
-
- def __setattr__(self, name, value):
- if name == '__dict__':
- raise AttributeError(
- "%r object attribute '__dict__' is read-only"
- % type(self))
-
- if name in _local_attrs:
- object.__setattr__(self, name, value)
- return
-
- dct = _local_get_dict(self)
-
- if self._local_type is local:
- # Optimization: If we're not subclassed, we can't
- # have data descriptors, so this goes right in the dict.
- dct[name] = value
- return
-
- if name in self._local_type_vars:
- if name in self._local_type_set_descriptors:
- type_attr = getattr(self._local_type, name, _marker)
- # A data descriptor, like a property or a slot.
- type(type_attr).__set__(type_attr, self, value)
- return
- # Otherwise it goes directly in the dict
- dct[name] = value
-
- def __delattr__(self, name):
- if name == '__dict__':
- raise AttributeError(
- "%r object attribute '__dict__' is read-only"
- % self.__class__.__name__)
-
- if name in self._local_type_vars:
- if name in self._local_type_del_descriptors:
- # A data descriptor, like a property or a slot.
- type_attr = getattr(self._local_type, name, _marker)
- type(type_attr).__delete__(type_attr, self)
- return
- # Otherwise it goes directly in the dict
-
- # Begin inlined function _get_dict()
- dct = _local_get_dict(self)
-
- try:
- del dct[name]
- except KeyError:
- raise AttributeError(name)
-
- def __copy__(self):
- impl = self._local__impl
- entry = impl.dicts[id(getcurrent())] # pylint:disable=undefined-variable
-
- dct = entry.localdict
- duplicate = copy(dct)
-
- cls = type(self)
- instance = cls(*impl.localargs, **impl.localkwargs)
- _local__copy_dict_from(instance, impl, duplicate)
- return instance
-
-def _local__copy_dict_from(self, impl, duplicate):
- current = getcurrent() # pylint:disable=undefined-variable
- currentId = id(current)
- new_impl = self._local__impl
- assert new_impl is not impl
- entry = new_impl.dicts[currentId]
- new_impl.dicts[currentId] = _localimpl_dict_entry(entry.wrgreenlet, duplicate)
-
-def _local_find_descriptors(self):
- type_self = type(self)
- gets = set()
- dels = set()
- set_or_del = set()
- sets = set()
- mro = list(type_self.mro())
-
- for attr_name in dir(type_self):
- # Conventionally, descriptors when called on a class
- # return themself, but not all do. Notable exceptions are
- # in the zope.interface package, where things like __provides__
- # return other class attributes. So we can't use getattr, and instead
- # walk up the dicts
- for base in mro:
- bd = base.__dict__
- if attr_name in bd:
- attr = bd[attr_name]
- break
- else:
- raise AttributeError(attr_name)
-
- type_attr = type(attr)
- if hasattr(type_attr, '__get__'):
- gets.add(attr_name)
- if hasattr(type_attr, '__delete__'):
- dels.add(attr_name)
- set_or_del.add(attr_name)
- if hasattr(type_attr, '__set__'):
- sets.add(attr_name)
-
- return (gets, dels, set_or_del, sets)
-
-# Cython doesn't let us use __new__, it requires
-# __cinit__. But we need __new__ if we're not compiled
-# (e.g., on PyPy). So we set it at runtime. Cython
-# will raise an error if we're compiled.
-def __new__(cls, *args, **kw):
- self = super(local, cls).__new__(cls)
- # We get the cls in *args for some reason
- # too when we do it this way....except on PyPy3, which does
- # not *unless* it's wrapped in a classmethod (which it is)
- self.__cinit__(*args[1:], **kw)
- return self
-
-try:
- # PyPy2/3 and CPython handle adding a __new__ to the class
- # in different ways. In CPython and PyPy3, it must be wrapped with classmethod;
- # in PyPy2, it must not. In either case, the args that get passed to
- # it are stil wrong.
- local.__new__ = 'None'
-except TypeError: # pragma: no cover
- # Must be compiled
- pass
-else:
- from gevent._compat import PYPY
- from gevent._compat import PY2
- if PYPY and PY2:
- local.__new__ = __new__
- else:
- local.__new__ = classmethod(__new__)
-
- del PYPY
- del PY2
-
-_init()
-
-from gevent._util import import_c_accel
-import_c_accel(globals(), 'gevent._local')