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83 lines
2.2 KiB
Python
83 lines
2.2 KiB
Python
5 years ago
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# -*- coding: utf-8 -*-
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# Copyright 2018 gevent contributors. See LICENSE for details.
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# cython: auto_pickle=False,embedsignature=True,always_allow_keywords=False
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from __future__ import absolute_import
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from __future__ import division
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from __future__ import print_function
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from weakref import WeakKeyDictionary
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from weakref import ref
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from heapq import heappop
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from heapq import heappush
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__all__ = [
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'IdentRegistry',
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]
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class ValuedWeakRef(ref):
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"""
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A weak ref with an associated value.
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"""
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__slots__ = ('value',)
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class IdentRegistry(object):
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"""
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Maintains a unique mapping of (small) non-negative integer identifiers
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to objects that can be weakly referenced.
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It is guaranteed that no two objects will have the the same
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identifier at the same time, as long as those objects are
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also uniquely hashable.
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"""
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def __init__(self):
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# {obj -> (ident, wref(obj))}
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self._registry = WeakKeyDictionary()
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# A heap of numbers that have been used and returned
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self._available_idents = []
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def get_ident(self, obj):
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"""
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Retrieve the identifier for *obj*, creating one
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if necessary.
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"""
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try:
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return self._registry[obj][0]
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except KeyError:
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pass
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if self._available_idents:
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# Take the smallest free number
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ident = heappop(self._available_idents)
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else:
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# Allocate a bigger one
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ident = len(self._registry)
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vref = ValuedWeakRef(obj, self._return_ident)
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vref.value = ident # pylint:disable=assigning-non-slot,attribute-defined-outside-init
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self._registry[obj] = (ident, vref)
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return ident
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def _return_ident(self, vref):
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# By the time this is called, self._registry has been
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# updated
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if heappush is not None:
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# Under some circumstances we can get called
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# when the interpreter is shutting down, and globals
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# aren't available any more.
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heappush(self._available_idents, vref.value)
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def __len__(self):
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return len(self._registry)
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from gevent._util import import_c_accel
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import_c_accel(globals(), 'gevent.__ident')
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