mirror of https://github.com/python/cpython
103 lines
2.8 KiB
Python
103 lines
2.8 KiB
Python
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"""Common code between queues and channels."""
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class ItemInterpreterDestroyed(Exception):
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"""Raised when trying to get an item whose interpreter was destroyed."""
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class classonly:
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"""A non-data descriptor that makes a value only visible on the class.
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This is like the "classmethod" builtin, but does not show up on
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instances of the class. It may be used as a decorator.
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"""
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def __init__(self, value):
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self.value = value
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self.getter = classmethod(value).__get__
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self.name = None
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def __set_name__(self, cls, name):
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if self.name is not None:
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raise TypeError('already used')
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self.name = name
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def __get__(self, obj, cls):
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if obj is not None:
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raise AttributeError(self.name)
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# called on the class
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return self.getter(None, cls)
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class UnboundItem:
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"""Represents a cross-interpreter item no longer bound to an interpreter.
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An item is unbound when the interpreter that added it to the
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cross-interpreter container is destroyed.
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"""
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__slots__ = ()
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@classonly
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def singleton(cls, kind, module, name='UNBOUND'):
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doc = cls.__doc__.replace('cross-interpreter container', kind)
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doc = doc.replace('cross-interpreter', kind)
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subclass = type(
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f'Unbound{kind.capitalize()}Item',
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(cls,),
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dict(
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_MODULE=module,
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_NAME=name,
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__doc__=doc,
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),
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)
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return object.__new__(subclass)
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_MODULE = __name__
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_NAME = 'UNBOUND'
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def __new__(cls):
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raise Exception(f'use {cls._MODULE}.{cls._NAME}')
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def __repr__(self):
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return f'{self._MODULE}.{self._NAME}'
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# return f'interpreters.queues.UNBOUND'
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UNBOUND = object.__new__(UnboundItem)
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UNBOUND_ERROR = object()
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UNBOUND_REMOVE = object()
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_UNBOUND_CONSTANT_TO_FLAG = {
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UNBOUND_REMOVE: 1,
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UNBOUND_ERROR: 2,
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UNBOUND: 3,
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}
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_UNBOUND_FLAG_TO_CONSTANT = {v: k
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for k, v in _UNBOUND_CONSTANT_TO_FLAG.items()}
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def serialize_unbound(unbound):
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op = unbound
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try:
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flag = _UNBOUND_CONSTANT_TO_FLAG[op]
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except KeyError:
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raise NotImplementedError(f'unsupported unbound replacement op {op!r}')
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return flag,
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def resolve_unbound(flag, exctype_destroyed):
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try:
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op = _UNBOUND_FLAG_TO_CONSTANT[flag]
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except KeyError:
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raise NotImplementedError(f'unsupported unbound replacement op {flag!r}')
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if op is UNBOUND_REMOVE:
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# "remove" not possible here
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raise NotImplementedError
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elif op is UNBOUND_ERROR:
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raise exctype_destroyed("item's original interpreter destroyed")
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elif op is UNBOUND:
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return UNBOUND
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else:
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raise NotImplementedError(repr(op))
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