threaded-decorator.py

import time
from queue import Queue
from threading import Thread


def threaded(f, daemon=False):

    def wrapped_f(q, *args, **kwargs):
        """this function calls the decorated function and puts the
        result in a queue"""
        ret = f(*args, **kwargs)
        q.put(ret)

    def wrap(*args, **kwargs):
        """this is the function returned from the decorator. It fires off
        wrapped_f in a new thread and returns the thread object with
        the result queue attached"""

        q = Queue()

        t = Thread(target=wrapped_f, args=(q,) + args, kwargs=kwargs)
        t.daemon = daemon
        t.start()
        t.result_queue = q
        return t

    return wrap


@threaded
def long_task(x, sleeptime=5):
    # x = x + 5
    time.sleep(sleeptime)
    return x


q = Queue()

for i in range(10):
    y = long_task(i)
    q.put(y)

for i in range(10, 20):
    y = long_task(i, 2)
    q.put(y)


while not q.empty():
    y = q.get()
    print(f"{y.result_queue.get()}   {y}")


# does not block, returns Thread object
# y = long_task(10)
# print(y)

# this blocks, waiting for the result
# result = y.result_queue.get()
# print(result)