Implementing base support for TCP-style window-based limiting on per-FIB-prefix and per-face granularity
Currently, limits are supported only by ndn::fw::Limits forwarding
strategy and only at the very basic (not fully tested) level.
diff --git a/utils/ndn-limits.cc b/utils/ndn-limits.cc
new file mode 100644
index 0000000..967c773
--- /dev/null
+++ b/utils/ndn-limits.cc
@@ -0,0 +1,131 @@
+/* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil -*- */
+/*
+ * Copyright (c) 2011 University of California, Los Angeles
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation;
+ *
+ * This program 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Author: Alexander Afanasyev <alexander.afanasyev@ucla.edu>
+ */
+
+#include "ndn-limits.h"
+
+#include "ns3/log.h"
+#include "ns3/simulator.h"
+
+NS_LOG_COMPONENT_DEFINE ("ndn.Limits");
+
+namespace ns3 {
+namespace ndn {
+
+NS_OBJECT_ENSURE_REGISTERED (Limits);
+
+TypeId
+Limits::GetTypeId ()
+{
+ static TypeId tid = TypeId ("ns3::ndn::Limits")
+ .SetGroupName ("Ndn")
+ .SetParent <Object> ()
+ .AddConstructor <Limits> ()
+
+ .AddTraceSource ("CurMaxLimit",
+ "Current maximum limit",
+ MakeTraceSourceAccessor (&Limits::m_curMaxLimit))
+
+ .AddTraceSource ("Outstanding",
+ "Number of outstanding interests",
+ MakeTraceSourceAccessor (&Limits::m_outstanding))
+ ;
+ return tid;
+}
+
+void
+Limits::SetMaxLimit (uint32_t max)
+{
+ m_maxLimit = max;
+ m_curMaxLimit = max;
+}
+
+
+void
+Limits::DecayCurrentLimit ()
+{
+ if (m_maxLimit == 0) return;
+
+ if (!m_lastDecay.IsZero ())
+ {
+ const double tau = 100.0; // seconds
+ double timeDiff = (Simulator::Now () - m_lastDecay).ToDouble (Time::S);
+
+ NS_LOG_DEBUG ("m_maxLimit - (m_maxLimit - m_curMaxLimit) * exp (-timeDiff / tau)");
+ NS_LOG_DEBUG (m_maxLimit << " - " << " ( " << m_maxLimit << " - " << (double)m_curMaxLimit << " ) " << " * " << " exp (- " << timeDiff << " / " << tau << " ) ");
+
+ m_curMaxLimit = m_maxLimit - (m_maxLimit - m_curMaxLimit) * exp (-timeDiff / tau);
+ }
+
+ m_lastDecay = Simulator::Now ();
+}
+
+void
+Limits::IncreaseLimit ()
+{
+ if (m_maxLimit == 0) return;
+
+ // Additive increase
+ m_curMaxLimit = std::min (1.0 * m_maxLimit,
+ (double)m_curMaxLimit + 1.0 / (double)m_curMaxLimit);
+}
+
+void
+Limits::DecreaseLimit ()
+{
+ if (m_maxLimit == 0) return;
+
+ const double maxDecreaseFrequency = 10.0;
+
+ if (!m_lastDecrease.IsZero () && Simulator::Now () - m_lastDecrease < Seconds (1 / maxDecreaseFrequency))
+ return;
+
+ // Multiplicative decrease... almost
+ m_curMaxLimit = 0.5 * m_curMaxLimit;
+
+ m_lastDecrease = Simulator::Now ();
+}
+
+
+bool
+Limits::IsBelowLimit ()
+{
+ if (m_maxLimit == 0) return true;
+
+ if (m_curMaxLimit - m_outstanding > 1.0)
+ {
+ m_outstanding += 1;
+ return true;
+ }
+ else
+ return false;
+}
+
+void
+Limits::RemoveOutstanding ()
+{
+ if (m_maxLimit == 0) return; //limits are disabled
+
+ NS_LOG_DEBUG (m_outstanding);
+ NS_ASSERT_MSG (m_outstanding >= 1, "Should not be possible, unless we decreasing this number twice somewhere");
+ m_outstanding -= 1;
+}
+
+} // namespace ndn
+} // namespace ns3