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
diff --git a/utils/ndn-limits.h b/utils/ndn-limits.h
new file mode 100644
index 0000000..b8ca50d
--- /dev/null
+++ b/utils/ndn-limits.h
@@ -0,0 +1,106 @@
+/* -*- 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>
+ */
+
+#ifndef _NDN_LIMITS_H_
+#define _NDN_LIMITS_H_
+
+#include "ns3/ptr.h"
+#include "ns3/object.h"
+#include "ns3/nstime.h"
+#include "ns3/traced-value.h"
+
+namespace ns3 {
+namespace ndn {
+
+/**
+ * \ingroup ndn
+ * \brief Structure to manage limits for outstanding interests
+ */
+class Limits :
+ public Object
+{
+public:
+ static TypeId
+ GetTypeId ();
+
+ /**
+ * \brief Constructor
+ * \param prefix smart pointer to the prefix for the FIB entry
+ */
+ Limits ()
+ : m_maxLimit (0)
+ , m_curMaxLimit (0)
+ , m_outstanding (0)
+ { }
+
+ /**
+ * Set per-prefix limit
+ */
+ void
+ SetMaxLimit (uint32_t max);
+
+ /**
+ * Decay current limit (exponential decaying)
+ */
+ void
+ DecayCurrentLimit ();
+
+ /**
+ * Increase current limit (additive increase)
+ */
+ void
+ IncreaseLimit ();
+
+ /**
+ * Decrease current limit (multiplicative decrease)
+ */
+ void
+ DecreaseLimit ();
+
+ ////////////////////////////////////////////////////////////////////////////
+ ////////////////////////////////////////////////////////////////////////////
+ ////////////////////////////////////////////////////////////////////////////
+
+ /**
+ * Check if new interest can be send out, if yes, number of outstanding will be increased
+ */
+ bool
+ IsBelowLimit ();
+
+ /**
+ * Remove outstanding interests
+ */
+ void
+ RemoveOutstanding ();
+
+public:
+ uint32_t m_maxLimit;
+
+ TracedValue< double > m_curMaxLimit;
+ TracedValue< uint32_t > m_outstanding;
+
+ Time m_lastDecrease;
+ Time m_lastDecay;
+};
+
+} // namespace ndn
+} // namespace ns3
+
+#endif // _NDN_LIMITS_H_