Function decorator that causes multiple calls to the same function from multiple threads to wait on one thread to actually perform the function. Works with recursive functions (via threading.RLock)

multithread_method_sync.py

import threading


def multithread_method_sync(method):
    rlock = threading.RLock()
    revent = threading.Event()
    # result has to be a list because of Python closure weirdness
    result = [None]
    
    def callable(*args, **kwargs):
        if rlock.acquire(blocking=False):
            if rlock._RLock__count == 1:
                revent.clear()
            result[0] = method(*args, **kwargs)
            rlock.release()
            if rlock._RLock__count == 0:
                revent.set()
        else:
            revent.wait()
        return result[0]
    
    return callable