commit 20fe4a9cb090e6babdfaa42bf239d74c0dbb6822
author Vince Lehman <vslehman@memphis.edu> Tue Sep 09 15:57:59 2014 -0500
committer Vince Lehman <vslehman@memphis.edu> Thu Oct 09 13:33:06 2014 -0700
tree 5dc47edfdf2792ba566028ffc3f771853861f5b4
parent 942eb7b67daebac036dc9067e7ca35eb5dfa5081

route: Fix hyperbolic cost adjustment

refs: #1974

Change-Id: Ic96c94d978487bbef2804235b75aa227c350d941

src/route/nexthop.hpp

diff --git a/src/route/nexthop.hpp b/src/route/nexthop.hpp
index b31d09a..0e409d2 100644
--- a/src/route/nexthop.hpp
+++ b/src/route/nexthop.hpp
@@ -23,6 +23,8 @@
 #ifndef NLSR_NEXTHOP_HPP
 #define NLSR_NEXTHOP_HPP
 
+#include "test-access-control.hpp"
+
 #include <iostream>
 #include <cmath>
 #include <boost/cstdint.hpp>
@@ -34,10 +36,12 @@
   NextHop()
     : m_connectingFaceUri()
     , m_routeCost(0)
+    , m_isHyperbolic(false)
   {
   }
 
   NextHop(const std::string& cfu, double rc)
+    : m_isHyperbolic(false)
   {
     m_connectingFaceUri = cfu;
     m_routeCost = rc;
@@ -58,7 +62,15 @@
   uint64_t
   getRouteCostAsAdjustedInteger() const
   {
-    return static_cast<uint64_t>(round(m_routeCost*HYPERBOLIC_COST_ADJUSTMENT_FACTOR));
+    if (m_isHyperbolic) {
+      // Round the cost to better preserve decimal cost differences
+      // e.g. Without rounding: 12.3456 > 12.3454 -> 12345 = 12345
+      //      With rounding:    12.3456 > 12.3454 -> 12346 > 12345
+      return static_cast<uint64_t>(round(m_routeCost*HYPERBOLIC_COST_ADJUSTMENT_FACTOR));
+    }
+    else {
+      return static_cast<uint64_t>(m_routeCost);
+    }
   }
 
   double
@@ -73,10 +85,35 @@
     m_routeCost = rc;
   }
 
+  void
+  setHyperbolic(bool b)
+  {
+    m_isHyperbolic = b;
+  }
+
+  bool
+  isHyperbolic() const
+  {
+    return m_isHyperbolic;
+  }
+
 private:
   std::string m_connectingFaceUri;
   double m_routeCost;
-  static const uint64_t HYPERBOLIC_COST_ADJUSTMENT_FACTOR = 100;
+  bool m_isHyperbolic;
+
+PUBLIC_WITH_TESTS_ELSE_PRIVATE:
+  /** \brief Used to adjust floating point route costs to integers
+  *   Since NFD uses integer route costs in the FIB, hyperbolic paths with similar route costs
+  *   will be rounded to integers and installed with identical nexthop costs.
+  *
+  *   e.g. costs 12.34 and 12.35 will be equal in NFD's FIB
+  *
+  *   This multiplier is used to differentiate similar route costs in the FIB.
+  *
+  *   e.g  costs 12.34 and 12.35 will be installed into NFD's FIB as 12340 and 12350
+  */
+  static const uint64_t HYPERBOLIC_COST_ADJUSTMENT_FACTOR = 1000;
 };
 
 std::ostream&

src/route/routing-table-calculator.cpp

diff --git a/src/route/routing-table-calculator.cpp b/src/route/routing-table-calculator.cpp
index dffe4a3..24707b0 100644
--- a/src/route/routing-table-calculator.cpp
+++ b/src/route/routing-table-calculator.cpp
@@ -461,6 +461,7 @@
                                              double cost, RoutingTable& rt)
 {
   NextHop hop(faceUri, cost);
+  hop.setHyperbolic(true);
 
   _LOG_TRACE("Calculated " << hop << " for destination: " << dest);