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#!@PYTHON@
# This file is part of GNUnet
# (C) 2013, 2018 Christian Grothoff (and other contributing authors)
#
# GNUnet is free software: you can redistribute it and/or modify it
# under the terms of the GNU Affero General Public License as published
# by the Free Software Foundation, either version 3 of the License,
# or (at your option) any later version.
#
# GNUnet is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
from __future__ import absolute_import
from __future__ import print_function
import argparse
import random
from math import ceil, log, floor
from past.builtins import xrange
def bsc(n):
""" count the bits set in n"""
l = n.bit_length()
c = 0
x = 1
for _ in range(0, l):
if n & x:
c = c + 1
x = x << 1
return c
def simulate(k, n, verbose):
assert k < n
largest_arc = int(2**ceil(log(n, 2))) / 2
num_ghosts = (2 * largest_arc) - n
if verbose:
print("we have", num_ghosts, "ghost peers")
# n.b. all peers with idx<k are evil
peers = range(n)
# py2-3 compatible, backwards.
# refer to http://python-future.org/compatible_idioms.html#xrange
info = [1 << x for x in xrange(n)]
def done_p():
for x in xrange(k, n):
if bsc(info[x]) < n-k:
return False
return True
rounds = 0
while not done_p():
if verbose:
print("-- round --")
arc = 1
while arc <= largest_arc:
if verbose:
print("-- subround --")
new_info = [x for x in info]
for peer_physical in xrange(n):
peer_logical = peers[peer_physical]
peer_type = None
partner_logical = (peer_logical + arc) % n
partner_physical = peers.index(partner_logical)
if peer_physical < k or partner_physical < k:
if verbose:
print("bad peer in connection", peer_physical, "--", partner_physical)
continue
if peer_logical & arc == 0:
# we are outgoing
if verbose:
print(peer_physical, "connects to", partner_physical)
peer_type = "outgoing"
if peer_logical < num_ghosts:
# we have a ghost, check if the peer who connects
# to our ghost is actually outgoing
ghost_partner_logical = (peer_logical - arc) % n
if ghost_partner_logical & arc == 0:
peer_type = peer_type + ", ghost incoming"
new_info[peer_physical] = new_info[peer_physical] | info[peer_physical] | info[partner_physical]
new_info[partner_physical] = new_info[partner_physical] | info[peer_physical] | info[partner_physical]
else:
peer_type = "incoming"
if verbose > 1:
print("type of", str(peer_physical) + ":", peer_type)
info = new_info
arc = arc << 1
rounds = rounds + 1
random.shuffle(peers)
return rounds
if __name__ == "__main__":
parser = argparse.ArgumentParser()
parser.add_argument("k", metavar="k", type=int, help="#(bad peers)")
parser.add_argument("n", metavar="n", type=int, help="#(all peers)")
parser.add_argument("r", metavar="r", type=int, help="#(rounds)")
parser.add_argument('--verbose', '-v', action='count')
args = parser.parse_args()
sum = 0.0
for n in xrange(0, args.r):
sum += simulate(args.k, args.n, args.verbose)
print(sum / args.r)
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