#!/usr/bin/env python3
# -*- coding: utf-8 -*-

__author__ = "Christian Heider Nielsen"
__doc__ = r"""

           Created on 01/08/2020
           """

import random
import time
from multiprocessing import Process, Queue, current_process, freeze_support


def worker(input, output):
  for func, args in iter(input.get, "STOP"):
    result = calculate(func, args)
    output.put(result)


def calculate(func, args):
  result = func(*args)
  return f"{current_process().name} says that {func.__name__}{args} = {result}"


def mul(a, b):
  time.sleep(0.5 * random.random())
  return a * b


def plus(a, b):
  time.sleep(0.5 * random.random())
  return a + b


def test():
  NUMBER_OF_PROCESSES = 4
  TASKS1 = [(mul, (i, 7)) for i in range(20)]
  TASKS2 = [(plus, (i, 8)) for i in range(10)]

  # Create queues
  task_queue = Queue()
  done_queue = Queue()

  for task in TASKS1:  # Submit tasks
    task_queue.put(task)

  for i in range(NUMBER_OF_PROCESSES):  # Start worker processes
    Process(target=worker, args=(task_queue, done_queue)).start()

  print("Unordered results:")
  for i in range(len(TASKS1)):  # Get and print results
    print("\t", done_queue.get())

  for task in TASKS2:  # Add more tasks using `put()`
    task_queue.put(task)

  for i in range(len(TASKS2)):  # Get and print some more results
    print("\t", done_queue.get())

  for i in range(NUMBER_OF_PROCESSES):  # Tell child processes to stop
    task_queue.put("STOP")


if __name__ == "__main__":
  freeze_support()
  test()
