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# Copyright (c) 2020 Matt Martz <matt@sivel.net>
# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
from __future__ import annotations
from functools import wraps
def lock_decorator(attr='missing_lock_attr', lock=None):
"""This decorator is a generic implementation that allows you
to either use a pre-defined instance attribute as the location
of the lock, or to explicitly pass a lock object.
This code was implemented with ``threading.Lock`` in mind, but
may work with other locks, assuming that they function as
context managers.
When using ``attr``, the assumption is the first argument to
the wrapped method, is ``self`` or ``cls``.
Examples:
@lock_decorator(attr='_callback_lock')
def send_callback(...):
@lock_decorator(lock=threading.Lock())
def some_method(...):
"""
def outer(func):
@wraps(func)
def inner(*args, **kwargs):
# Python2 doesn't have ``nonlocal``
# assign the actual lock to ``_lock``
if lock is None:
_lock = getattr(args[0], attr)
else:
_lock = lock
with _lock:
return func(*args, **kwargs)
return inner
return outer
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