From 210be82b7cdc6058401e7d5042aa50dd0b750c92 Mon Sep 17 00:00:00 2001
From: Florian Dold <florian.dold@gmail.com>
Date: Thu, 11 Apr 2013 10:08:52 +0000
Subject: added consensus log-round simulation, work on consensus service,
 still problems with dv test case

---
 src/consensus/consensus-simulation.py | 103 ++++++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)
 create mode 100644 src/consensus/consensus-simulation.py

(limited to 'src/consensus/consensus-simulation.py')

diff --git a/src/consensus/consensus-simulation.py b/src/consensus/consensus-simulation.py
new file mode 100644
index 000000000..930dfee62
--- /dev/null
+++ b/src/consensus/consensus-simulation.py
@@ -0,0 +1,103 @@
+#!/usr/bin/python
+# This file is part of GNUnet
+# (C) 2013 Christian Grothoff (and other contributing authors)
+#
+# GNUnet is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published
+# by the Free Software Foundation; either version 2, 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
+# General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with GNUnet; see the file COPYING.  If not, write to the
+# Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+# Boston, MA 02111-1307, USA.
+
+import argparse
+import random
+from math import ceil,log,floor
+
+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)
+  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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