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from __future__ import absolute_import
import binascii
import weakref
from kafka.vendor import six
if six.PY3:
MAX_INT = 2 ** 31
TO_SIGNED = 2 ** 32
def crc32(data):
crc = binascii.crc32(data)
# py2 and py3 behave a little differently
# CRC is encoded as a signed int in kafka protocol
# so we'll convert the py3 unsigned result to signed
if crc >= MAX_INT:
crc -= TO_SIGNED
return crc
else:
from binascii import crc32
class WeakMethod(object):
"""
Callable that weakly references a method and the object it is bound to. It
is based on https://stackoverflow.com/a/24287465.
Arguments:
object_dot_method: A bound instance method (i.e. 'object.method').
"""
def __init__(self, object_dot_method):
try:
self.target = weakref.ref(object_dot_method.__self__)
except AttributeError:
self.target = weakref.ref(object_dot_method.im_self)
self._target_id = id(self.target())
try:
self.method = weakref.ref(object_dot_method.__func__)
except AttributeError:
self.method = weakref.ref(object_dot_method.im_func)
self._method_id = id(self.method())
def __call__(self, *args, **kwargs):
"""
Calls the method on target with args and kwargs.
"""
return self.method()(self.target(), *args, **kwargs)
def __hash__(self):
return hash(self.target) ^ hash(self.method)
def __eq__(self, other):
if not isinstance(other, WeakMethod):
return False
return self._target_id == other._target_id and self._method_id == other._method_id
class Dict(dict):
"""Utility class to support passing weakrefs to dicts
See: https://docs.python.org/2/library/weakref.html
"""
pass
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