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#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
Calculate congestion delay for circuit.
"""
# Author: Robert Annessi <robert.annessi@nt.tuwien.ac.at>
# License: GPLv2 (2015-2016)
from cPickle import load
from argparse import ArgumentParser
from numpy import average
from os.path import exists
from cPickle import dump, HIGHEST_PROTOCOL
from collections import namedtuple
Probedata = namedtuple('Probedata', 'date entry middle exit cbt rtts perfs bws cong')
def _main():
# found empirically by CAT authors
gamma = 20
# maximum number of congestion measurements for each relay
# (from CAT authors)
L = 20
# initialization value (medmed congestion delay of nodes ~= 5)
cong_init = 5
relay_congestion = dict()
parser = ArgumentParser(description="")
parser.add_argument("--input", type=str, required=True,
help="Input file.")
parser.add_argument("--output", type=str, required=True,
help="Output file.")
args = parser.parse_args()
assert exists(args.input), 'Invalid input file.'
assert not exists(args.output), 'Invalid output file.'
probes = []
with open(args.input, 'r') as f:
while True:
try:
probes.append(load(f))
except EOFError:
break
with open(args.output, 'w') as f:
for probe in probes:
# Check type and number of RTT measurements
rtts = [rtt for rtt in probe.rtts if isinstance(rtt, int)]
if len(rtts) != 5:
probedata = Probedata(date=probe.date, entry=probe.entry,
middle=probe.middle, exit=probe.exit,
cbt=probe.cbt, rtts=probe.rtts,
perfs=probe.perfs, bws=probe.bws,
cong=None)
dump(probedata, f, HIGHEST_PROTOCOL)
continue
# Create congestion entry for relay if it does not exist yet.
for i in probe.entry, probe.middle, probe.exit:
if i not in relay_congestion:
relay_congestion[i] = [cong_init]
# Get reference value and remove it from the list for comparison
t_min = min(rtts)
rtts.remove(t_min)
for rtt in rtts:
# calculate congestion delay for each node
T_c = rtt - t_min + gamma
t_c_1 = T_c * 2 * average(relay_congestion[probe.entry]) / (2 * average(relay_congestion[probe.entry]) + 2 * average(relay_congestion[probe.middle]) + average(relay_congestion[probe.exit]))
t_c_2 = T_c * 2 * average(relay_congestion[probe.middle]) / (2 * average(relay_congestion[probe.entry]) + 2 * average(relay_congestion[probe.middle]) + average(relay_congestion[probe.exit]))
t_c_3 = T_c * average(relay_congestion[probe.exit]) / (2 * average(relay_congestion[probe.entry]) + 2 * average(relay_congestion[probe.middle]) + average(relay_congestion[probe.exit]))
# delete initialization value if still present
for i in probe.entry, probe.middle, probe.exit:
if len(relay_congestion[i]) == 1 and relay_congestion[i][0] == cong_init:
del relay_congestion[i][0]
# add new congestion delays to nodes and delete oldest value
# if max number of measurements is reached
relay_congestion[probe.entry].append(t_c_1)
if len(relay_congestion[probe.entry]) > L:
del relay_congestion[probe.entry][0]
relay_congestion[probe.middle].append(t_c_2)
if len(relay_congestion[probe.middle]) > L:
del relay_congestion[probe.middle][0]
relay_congestion[probe.exit].append(t_c_3)
if len(relay_congestion[probe.exit]) > L:
del relay_congestion[probe.exit][0]
# calculate congestion delay for circuit
congestion = average(relay_congestion[probe.entry]) + average(relay_congestion[probe.middle]) + average(relay_congestion[probe.exit])
probedata = Probedata(date=probe.date, entry=probe.entry,
middle=probe.middle, exit=probe.exit,
cbt=probe.cbt, rtts=probe.rtts,
perfs=probe.perfs, bws=probe.bws,
cong=int(round(congestion)))
dump(probedata, f, HIGHEST_PROTOCOL)
if __name__ == '__main__':
_main()