Two Queue simluation example

two_queue.py

import logging
from math import inf, log
from random import random as rand


log_format ='%(asctime)s.%(msecs)03d %(levelname)8s [%(module)s %(funcName)s] %(message)s'
datefmt ="%Y-%m-%d %H:%M:%S"
logger_level = logging.WARN
logging.basicConfig(level=logger_level, format=log_format, datefmt=datefmt)
logger = logging.getLogger(__name__)


def min2(arr):
    v = min(arr)
    i = arr.index(v)
    return v, i


def mean(arr):
    return sum(arr) / len(arr)


def list_subtract(a, b):
    return list(map(
        lambda tup: tup[0] - tup[1],
        zip(a, b)))


def two_queue(lambda_, mu1, mu2, simtime):
    logger.info('Simulation params')
    logger.info('=================')
    logger.info(f'lambda: {lambda_}')
    logger.info(f'mu_1: {mu1}')
    logger.info(f'mu_2: {mu2}')
    logger.info(f'simulation time: {simtime}')

    t = 0
    q = [0, 0]
    ttne = [-log(rand()) / lambda_, inf, inf]

    arrivals = 0
    departures = 0

    arrival_times = []
    depature_times = []

    while t < simtime:
        min_value, queue_index = min2(ttne)
        logger.debug(f'next event in {min_value} at queue {queue_index + 1}')
        t += min_value
        ttne = [i - min_value for i in ttne]

        if queue_index == 0:
            logger.debug('new arrival at queue 1')
            arrivals += 1
            arrival_times.append(t)
            q[0] += 1
            ttne[0] = -log(rand()) / lambda_
            if ttne[1] == inf:
                ttne[1] = -log(rand()) / mu1

        elif queue_index == 1:
            logger.debug('event moved to queue 2')
            q[0] -= 1
            q[1] += 1
            if q[0] > 0:
                ttne[1] = -log(rand()) / mu1
            else:
                ttne[1] = inf

            if ttne[2] == inf:
                ttne[2] = -log(rand()) / mu2

        else:
            logger.debug('event departure')
            q[1] -= 1
            departures += 1
            depature_times.append(t)
            if q[1] > 0:
                ttne[2] = -log(rand()) / mu2
            else:
                ttne[2] = inf

        logger.info(f'simtime: {t}')
        logger.debug(f'ttne: {ttne}')

    throughput = departures / t
    avg_response = mean(
            list_subtract(depature_times, arrival_times[:departures]))
    #  throughput = departures
    #  avg_response = [depature_times[1:10], arrival_times[1:10]]
    return throughput, avg_response


if __name__ == '__main__':
    print(two_queue(5, 2, 3, 1000))