#!/usr/bin/env python
# Wojciech Jamrozy
# Script written during Operating Systems course VI 2009
# Problem: The Senate Bus Problem
from time import sleep
from threading import Lock, Thread, Condition, Semaphore
from random import random
import sys
waiting_passengers = 0
mutex = Lock()
bus = Condition()
on_board = Semaphore(0)
 
class Configuration:
        NUMBER_OF_BUSES = 15
        NUMBER_OF_PASSENGERS = 100
        BUS_DELAY = 5
        PASSENGER_DELAY = .8
        TIME_OF_BOARDING = 1
        SEATS = 10
 
 
class Bus(Thread):
    def __init__(self, numer):
        Thread.__init__(self)
        self.numer = numer
    def run(self):
        mutex.acquire()
        print "Bus %d arrived" % (self.numer,)
        global waiting_passengers
        n = min(waiting_passengers, Configuration.SEATS)
        for i in range(n):
            bus.acquire()
            bus.notify()
            bus.release()
            on_board.acquire()
            waiting_passengers -= 1
        sleep(Configuration.TIME_OF_BOARDING*random())
        print "Bus %d departed" % (self.numer,)
        mutex.release()
 
 
 
 
class Passenger(Thread):
    def __init__(self, numer):
        Thread.__init__(self)
        self.numer = numer
    def run(self):
        global waiting_passengers
        print "Passenger %d has come" % (self.numer,)
        mutex.acquire()
        waiting_passengers += 1
        mutex.release()
        bus.acquire()
        bus.wait()
        print "Passenger %d is on board" % (self.numer,)
        bus.release()
        on_board.release()
 
 
class CreateBuses(Thread):
    def run(self):
        for i in range(Configuration.NUMBER_OF_BUSES):
            b = Bus(i)
            b.start()
            sleep(random()*Configuration.BUS_DELAY)
        print "Creating buses finished - nacisnij ENTER aby zakonczyc"
 
class CreatePassengers(Thread):
    def run(self):
        for i in range(Configuration.NUMBER_OF_PASSENGERS):
            o = Passenger(i)
            o.start()
            sleep(random()*Configuration.PASSENGER_DELAY)
        print "Creating passengers finished - press ENTER in order to finish"
 
busy = CreateBuses()
passengers = CreatePassengers()
 
busy.start()
passengers.start()
 
raw_input("Press any key in order to finish\n") 
sys.exit()