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from SimPy.Simulation import *
import random
"""carwash.py
Scenario:
A carwash installation has nrMachines washing machines which wash a car in washTime minutes.
Cars arrive with a negative exponential interarrival time with a mean of tInter
minutes.
Model the carwash operation as cooperation between two processes, the car being
washed and the machine doing the washing.
Build two implementations:
Model 1: the machine is master, the car slave;
Model 2: the car is master, the machine is slave.
"""
##Data:
nrMachines=2
tInter=2 #minutes
washtime=3.5 #minutes
initialSeed=123456
simTime=100
#####################################################
## Model 1: Carwash is master, car is slave
#####################################################
class Carwash(Process):
"""Carwash machine; master"""
def __init__(self,name):
Process.__init__(self,name)
self.carBeingWashed=None
def lifecycle(self):
while True:
yield get,self,waitingCars,1
self.carBeingWashed=self.got[0]
yield hold,self,washtime
self.carBeingWashed.doneSignal.signal(self.name)
class Car(Process):
"""Car; slave"""
def __init__(self,name):
Process.__init__(self,name)
self.doneSignal=SimEvent()
def lifecycle(self):
yield put,self,waitingCars,[self]
yield waitevent,self,self.doneSignal
whichWash=self.doneSignal.signalparam
print "%s: %s done by %s"%(now(),self.name,whichWash)
class CarGenerator(Process):
"""Car arrival generation"""
def generate(self):
i=0
while True:
yield hold,self,r.expovariate(1.0/tInter)
c=Car("car%s"%i)
activate(c,c.lifecycle())
i+=1
print "Model 1: carwash is master"
print "--------------------------"
initialize()
r=random.Random()
r.seed(initialSeed)
waiting=[]
for j in range(1,5):
c=Car("car%s"%-j)
activate(c,c.lifecycle())
waiting.append(c)
waitingCars=Store(capacity=40,initialBuffered=waiting)
cw=[]
for i in range(2):
c=Carwash("Carwash %s"%`i`)
cw.append(c)
activate(c,c.lifecycle())
cg=CarGenerator()
activate(cg,cg.generate())
simulate(until=simTime)
print "waiting cars: %s"%[x.name for x in waitingCars.theBuffer]
print "cars being washed: %s"%[y.carBeingWashed.name for y in cw]
#####################################################
## Model 2: Car is master, carwash is slave
#####################################################
class CarM(Process):
"""Car is master"""
def __init__(self,name):
Process.__init__(self,name)
def lifecycle(self):
yield get,self,washers,1
whichWash=self.got[0]
carsBeingWashed.append(self)
yield hold,self,washtime
print "%s: %s done by %s"%(now(),self.name,whichWash.name)
whichWash.doneSignal.signal()
carsBeingWashed.remove(self)
class CarwashS(Process):
def __init__(self,name):
Process.__init__(self,name)
self.doneSignal=SimEvent()
def lifecycle(self):
while True:
yield put,self,washers,[self]
yield waitevent,self,self.doneSignal
class CarGenerator1(Process):
def generate(self):
i=0
while True:
yield hold,self,r.expovariate(1.0/tInter)
c=CarM("car%s"%i)
activate(c,c.lifecycle())
i+=1
print "\nModel 2: car is master"
print "----------------------"
initialize()
r=random.Random()
r.seed(initialSeed)
washers=Store(capacity=nrMachines)
carsBeingWashed=[]
for j in range(1,5):
c=CarM("car%s"%-j)
activate(c,c.lifecycle())
for i in range(2):
cw=CarwashS("Carwash %s"%`i`)
activate(cw,cw.lifecycle())
cg=CarGenerator1()
activate(cg,cg.generate())
simulate(until=simTime)
print "waiting cars: %s"%[x.name for x in washers.getQ]
print "cars being washed: %s"%[x.name for x in carsBeingWashed]
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