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dcf.py
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dcf.py
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#!/usr/bin/python
'''
Grady Denton & Shane Bennett for proj3 in cnt5505 data comm
'''
#***Check to make sure we need all these***
#from __future__ import division
import argparse
import os
from collections import deque
from copy import deepcopy
from random import *
#from nonrandom import * #TEST deterministic random for TESTING
#*** Function definitions ***
#returns a time 0 to 15 at first
#numBackOffs increments when an ack is not received
def binExpBackoff(numOfBackoffs, slotTime):
if(numOfBackoffs == 0):
slotsToWait = randint(0, 15)
elif(numOfBackoffs >=6):
slotsToWait = randint(0, 1024)
else:
slotsToWait = randint(0, (32 * (2 ** (numOfBackoffs-1))))
return slotsToWait * slotTime
#ceiling division
def ceildiv(a, b):
return -(-a // b)
#*** set up arguments ***
parser = argparse.ArgumentParser(prog='DCF', description='Simulates the 802.11 DCF MAC protocol for a given traffic file.')
parser.add_argument("-t","--trafficfile", help="traffic file", default=os.path.join(os.getcwd(), "traffic"))
parser.add_argument("-o","--outfile", help="output file", default=os.path.join(os.getcwd(), "DCF.out"))
args = parser.parse_args()
#*** check arguments ***
trafficfile = os.path.expanduser(args.trafficfile)
if not os.path.exists(trafficfile):
parser.error('The trafficfile file does not exist!')
if not os.path.isfile(trafficfile):
parser.error('The trafficfile file is not a file!')
if not os.access(trafficfile, os.R_OK):
parser.error('The trafficfile file is not readable!')
outfile = os.path.basename(os.path.expanduser(args.outfile))
outDir = os.path.dirname(os.path.expanduser(args.outfile))
if not outDir:
outDir = os.getcwd()
if not os.path.exists(outDir):
parser.error('The out dir does not exist!')
if not os.path.isdir(outDir):
parser.error('The out dir is not a directory!')
if not os.access(outDir, os.W_OK):
parser.error('The outDir dir is not writable!')
#****** MAIN FUNCTION ******
#*** Vars ***
waiting_qwee = []
outPath = outDir + "/" + outfile
numNodes = 0
numOfCollisions = 0
timeMediaUtilized = 0 #increment this by (pkt_size/dataRate) when a packet successfully sends
totalTime = 0 #set this equal to the time the last packet successfully finishes transmission
numOfTransmissions = 0 #increment each time a packet attempts transmission
numPktPerNode = []
timeMediaBusy = 0
dataRate = 6 #Mbps, 6 bits are sent per microsecond
ackTime = 44 #us
slotTime = 9 #us
difsTime = 28 #us
sifsTime = 10 #us
# do stuff
with open(outPath, 'w') as of:
with open(trafficfile, 'r') as tf:
stats = tf.readline()
stats = stats.split()
numPackets = int(stats[0])
#offerdLoad = float(stats[1]) #NOTE !!!!! COMMENT OUT FOR TURN IN !!!!!! #NOTE
for line in tf:
#**** line format *************
#packet[0] : pkt_id *
#packet[1] : src_node *
#packet[2] : dst_node *
#packet[3] : pkt_size *
#packet[4] : time *
#packet[5] : time_to_backoff *
#packet[6] : num_backoffs *
#******************************
packet = line.split()
packet = [int(x) for x in packet]
while(numNodes < packet[1] + 1):
numPktPerNode.append(0)
waiting_qwee.append(deque())
numNodes = numNodes + 1
#count number of packets sent by each node
numPktPerNode[packet[1]] += 1
packet.append(0) #time_to_backoff
packet.append(0) #num_backoffs
waiting_qwee[packet[1]].append(packet)
#^^^^^^^^^^^^^^^^End of Reading File^^^^^^^^^^^^^^^^
#increment this by "wait time" whenever a packet must wait to send
#per node statistic
totalLatencyPerNode = [0] * numNodes
#**** waiting_qwee format *****************
#waiting_qwee[i][0][0] : pkt_id *
#waiting_qwee[i][0][1] : src_node *
#waiting_qwee[i][0][2] : dst_node *
#waiting_qwee[i][0][3] : pkt_size *
#waiting_qwee[i][0][4] : time *
#waiting_qwee[i][0][5] : *
#waiting_qwee[i][0][6] : num_backoffs *
#******************************************
#******************** Real Meaty Code ********************
#networkState[nodeID] = [currentStatusType, timeTillNextThing, slotsTimeLeft, normal/freezed/backoff]
networkState = [[0, 0, 0, 0] for i in range(numNodes)]
#currentStatusType
#0 -- waiting for packet from application
#1 -- waiting for DIFS
#2 -- waiting for slots
#3 -- waiting for packet transmission
#4 -- waiting for packet ACK
#5 -- got interrupted, waiting for nonbusy medium
#Printout statements we need
#Node x had y more slots when the channel became busy!
#set the next event for each node to be when first packet for that node arrives
for i in range(numNodes):
if(waiting_qwee[i]):
networkState[i][1] = waiting_qwee[i][0][4]
else:
networkState[i][1] = 999999999
isBusy = 0 #whether medium is currently sending
sending = 0 #how many node currently transmitting
collision = 0 #whether we collided
time = 0
#******************** A Wild Main Loop Appears! ********************
while(1):
#------------find the next event------------
#if medium isn't busy then any event can win
#but node starting to send takes least precedence
shortestTime = 999999999
for i in range(numNodes):
if(waiting_qwee[i]):
if(not isBusy):
if(networkState[i][1] < shortestTime):
shortestTime = networkState[i][1]
nodeWhoGetsTurn = i
elif(networkState[i][1] == shortestTime and networkState[nodeWhoGetsTurn][0] == 2):
nodeWhoGetsTurn = i
else: #isBusy
#only let those with state 0, 3, or 4 continue; let state 2 continue if it was a collisions(if timeTillNextThing == 0)
if(networkState[i][1] < shortestTime and (networkState[i][0] == 0 or networkState[i][0] == 3 or networkState[i][0] == 4 or (networkState[i][0] == 2 and networkState[i][1] == 0)) ):
shortestTime = networkState[i][1]
nodeWhoGetsTurn = i
#if no more events we are done
if(shortestTime == 999999999):
totalTime = time
break
#update current time
oldtime = time
time = time + networkState[nodeWhoGetsTurn][1]
#|||||||Process the Event|||||||
#if node is starting to wait for DIFS
if(networkState[nodeWhoGetsTurn][0] == 0):
pass
#of.write("Time: {} Node {} started waiting for DIFS\n".format(time, waiting_qwee[nodeWhoGetsTurn][0][1]))
#if node has finished waiting for DIFS
elif(networkState[nodeWhoGetsTurn][0] == 1):
#check if node already picked slots
if(networkState[nodeWhoGetsTurn][2] == 0):
networkState[nodeWhoGetsTurn][1] = binExpBackoff(waiting_qwee[nodeWhoGetsTurn][0][6], slotTime)
waiting_qwee[nodeWhoGetsTurn][0][6] += 1
else:
networkState[nodeWhoGetsTurn][1] = networkState[nodeWhoGetsTurn][2]
networkState[nodeWhoGetsTurn][2] = 0
#if node was not interrupted
if(networkState[nodeWhoGetsTurn][3] == 0):
of.write("Time: {} Node {} finished waiting for DIFS and started waiting for {} slots\n".format(time, waiting_qwee[nodeWhoGetsTurn][0][1], networkState[nodeWhoGetsTurn][1]/slotTime))
#if node was freezed
elif(networkState[nodeWhoGetsTurn][3] == 1):
of.write("Time: {} Node {} finished waiting for DIFS and started waiting for {} slots (counter was frozen)\n".format(time, waiting_qwee[nodeWhoGetsTurn][0][1], networkState[nodeWhoGetsTurn][1]/slotTime))
networkState[nodeWhoGetsTurn][3] = 0
#if node did backoff
elif(networkState[nodeWhoGetsTurn][3] == 2):
of.write("Time: {} Node {} finished waiting for DIFS and started waiting for {} slots (back off after collision)\n".format(time, waiting_qwee[nodeWhoGetsTurn][0][1], networkState[nodeWhoGetsTurn][1]/slotTime))
networkState[nodeWhoGetsTurn][3] = 0
#if node has finished waiting for slots
elif(networkState[nodeWhoGetsTurn][0] == 2):
of.write("Time: {} Node {} finished waiting and is ready to send the packet.\n".format(time, waiting_qwee[nodeWhoGetsTurn][0][1]))
#if node has finished waiting for transmission
elif(networkState[nodeWhoGetsTurn][0] == 3):
if(collision):
of.write("Time: {} Node {} has detected a collision\n".format(time, waiting_qwee[nodeWhoGetsTurn][0][1], waiting_qwee[nodeWhoGetsTurn][0][3]))
#if node has finished waiting for ACK
elif(networkState[nodeWhoGetsTurn][0] == 4):
of.write("Time: {} Node {} sent {} bits\n".format(time, waiting_qwee[nodeWhoGetsTurn][0][1], waiting_qwee[nodeWhoGetsTurn][0][3]))
elif(networkState[nodeWhoGetsTurn][0] == 5):
if(networkState[nodeWhoGetsTurn][2] != 0):
if (networkState[nodeWhoGetsTurn][3] == 1):
of.write("Time: {} Node {} had {} more slots when the channel became busy!\n".format(time, waiting_qwee[nodeWhoGetsTurn][0][1], networkState[nodeWhoGetsTurn][2]/slotTime))
elif(networkState[nodeWhoGetsTurn][3] == 2):
of.write("Time: {} Node {} had detected a collision and decided to backoff {} slots\n".format(time, waiting_qwee[nodeWhoGetsTurn][0][1], networkState[nodeWhoGetsTurn][2]/slotTime))
of.write("Time: {} Node {} started waiting for DIFS\n".format(time, waiting_qwee[nodeWhoGetsTurn][0][1]))
#--------------UPDATE NETWORKSTATE--------------
#update all the other nodes
for i in range(numNodes):
if(waiting_qwee[i] and i != nodeWhoGetsTurn):
if(isBusy):
if(networkState[i][0] == 0 or networkState[i][0] == 3):
networkState[i][1] = networkState[i][1] - (time-oldtime)
else: #if not Busy
networkState[i][1] = networkState[i][1] - (time-oldtime)
if(networkState[nodeWhoGetsTurn][0] == 2):
if(networkState[i][0] == 2 and networkState[i][1] != 0):
networkState[i][2] = (ceildiv(networkState[i][1],slotTime)) * slotTime
networkState[i][0] = 5
networkState[i][1] = 0
networkState[i][3] = 1
elif(networkState[i][0] == 1):
networkState[i][0] = 5
networkState[i][1] = 0
#update the node who got the turn
if(networkState[nodeWhoGetsTurn][0] == 0): #if done waiting for packet
networkState[nodeWhoGetsTurn][0] = 5
networkState[nodeWhoGetsTurn][1] = 0
networkState[nodeWhoGetsTurn][2] = 0
networkState[nodeWhoGetsTurn][3] = 0
elif(networkState[nodeWhoGetsTurn][0] == 1): #if done waiting for DIFS
networkState[nodeWhoGetsTurn][0] = 2
elif(networkState[nodeWhoGetsTurn][0] == 2): #if done waiting for slots
networkState[nodeWhoGetsTurn][0] = 3
networkState[nodeWhoGetsTurn][1] = ceildiv(waiting_qwee[nodeWhoGetsTurn][0][3],dataRate)
networkState[nodeWhoGetsTurn][2] = 0
isBusy = 1
sending += 1
numOfTransmissions += 1
if(sending > 1):
collision = 1
elif(networkState[nodeWhoGetsTurn][0] == 3): #if done waiting for transmission
if(collision): #do binary backoff and reset to waiting for DIFS
networkState[nodeWhoGetsTurn][2] = binExpBackoff(waiting_qwee[nodeWhoGetsTurn][0][6], slotTime)
waiting_qwee[nodeWhoGetsTurn][0][6] += 1
networkState[nodeWhoGetsTurn][0] = 5
networkState[nodeWhoGetsTurn][1] = 0
networkState[nodeWhoGetsTurn][3] = 2
numOfCollisions += 1
sending -= 1
if(sending == 0):
collision = 0
isBusy = 0
timeMediaBusy += ceildiv(waiting_qwee[nodeWhoGetsTurn][0][3],dataRate)
else: #no collision
timeMediaUtilized += ceildiv(waiting_qwee[nodeWhoGetsTurn][0][3],dataRate)
totalLatencyPerNode[nodeWhoGetsTurn] += time - waiting_qwee[nodeWhoGetsTurn][0][4]
networkState[nodeWhoGetsTurn][0] = 4
networkState[nodeWhoGetsTurn][1] = sifsTime + ackTime
elif(networkState[nodeWhoGetsTurn][0] == 4): #if done waiting for ACK
timeMediaBusy += ceildiv(waiting_qwee[nodeWhoGetsTurn][0][3],dataRate) +ackTime
waiting_qwee[nodeWhoGetsTurn].popleft()
networkState[nodeWhoGetsTurn][0] = 0
sending -= 1
isBusy = 0
if waiting_qwee[nodeWhoGetsTurn]:
if(waiting_qwee[nodeWhoGetsTurn][0][4] <= time):
networkState[nodeWhoGetsTurn][1] = 0
else:
networkState[nodeWhoGetsTurn][1] = waiting_qwee[nodeWhoGetsTurn][0][4] - time
else:
networkState[nodeWhoGetsTurn][1] = 999999999
elif(networkState[nodeWhoGetsTurn][0] == 5): #if started to wait for DIFS after interrupt
networkState[nodeWhoGetsTurn][0] = 1
networkState[nodeWhoGetsTurn][1] = difsTime
statfile = outDir + "/" + outfile + ".stats"
#**** Output some statistics here ****
throughput = float(timeMediaUtilized) / totalTime * dataRate
fracMediaFree = float(totalTime - timeMediaBusy) / totalTime
#fracMediaFree = float((totalTime - timeMediaUtilized)) / totalTime
avgLatencyPerNode = float(sum(totalLatencyPerNode)) / sum(numPktPerNode)
stats = [offerdLoad,throughput,numOfTransmissions,numOfCollisions,fracMediaFree,numPktPerNode[0],avgLatencyPerNode]
stats = [str(x) for x in stats]
#with open(statfile, 'w') as sf:
#sf.write(','.join(stats))
print "timeMediaUtilized: ", timeMediaUtilized, u'\u00b5'
print "dataRate: ", dataRate, " Mbps"
print "totalTime: ", totalTime, u'\u00b5'
print "throughput: ", throughput, " Mbps"
print "fracMediaFree: ", fracMediaFree
print "totalLatencyPerNode: ", totalLatencyPerNode
print "numPktPerNode: ", numPktPerNode
print "avgLatencyPerNode: ", avgLatencyPerNode, u'\u00b5'