Simple Lock decorator for bound methods

with_lock.py

import threading
import functools

def with_lock(func):
    """ Synchronization decorator applicable to bound methods, which
    creates a threading.Lock for the decorated function, which is then acquired
    on every call to the method.
    Locks created will be stored in the dict self._func_locks. """
    @functools.wraps(func)
    def wrapped(self, *args, **kwargs):
        try:
            lock = self._func_locks[func]
        except AttributeError:
            # self._func_locks doesnt exist yet
            self._func_locks = {}
            lock = self._func_locks[func] = threading.Lock()
        except KeyError:
            # self._func_locks[func] doesnt exist yet
            lock = self._func_locks[func] = threading.Lock()
        
        lock.acquire()
        try:
            return func(self, *args, **kwargs)
        finally:
            lock.release()
    return wrapped