table: capacity limit in PIT NonceList
refs #1770
Change-Id: Ia5722968cca1d9a4bbf3ef19e57be73eac702a69
diff --git a/daemon/table/pit-nonce-list.cpp b/daemon/table/pit-nonce-list.cpp
new file mode 100644
index 0000000..02502ab
--- /dev/null
+++ b/daemon/table/pit-nonce-list.cpp
@@ -0,0 +1,66 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014, Regents of the University of California,
+ * Arizona Board of Regents,
+ * Colorado State University,
+ * University Pierre & Marie Curie, Sorbonne University,
+ * Washington University in St. Louis,
+ * Beijing Institute of Technology,
+ * The University of Memphis
+ *
+ * This file is part of NFD (Named Data Networking Forwarding Daemon).
+ * See AUTHORS.md for complete list of NFD authors and contributors.
+ *
+ * NFD 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 3 of the License, or (at your option) any later version.
+ *
+ * NFD 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
+ * NFD, e.g., in COPYING.md file. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "pit-nonce-list.hpp"
+
+namespace nfd {
+namespace pit {
+
+// The NonceList has limited capacity to avoid memory explosion
+// if PIT entry is constantly refreshed (NFD Bug #1770).
+// Current implementation keeps nonces in a set to detect duplicates,
+// and a queue to evict the oldest nonce when capacity limit is reached.
+// A limitation is that a nonce first appeared at time 0 and duplicated at time 10
+// could be evicted before a nonce appeared only once at time 5;
+// this limitation should not affect normal operation.
+
+const size_t NonceList::CAPACITY = 256;
+
+NonceList::NonceList()
+{
+}
+
+bool
+NonceList::add(uint32_t nonce)
+{
+ bool isNew = m_nonceSet.insert(nonce).second;
+ if (!isNew)
+ return false;
+
+ m_nonceQueue.push(nonce);
+ BOOST_ASSERT(m_nonceSet.size() == m_nonceQueue.size());
+
+ if (m_nonceSet.size() > CAPACITY) {
+ size_t nErased = m_nonceSet.erase(m_nonceQueue.front());
+ BOOST_ASSERT(nErased == 1);
+ m_nonceQueue.pop();
+ BOOST_ASSERT(m_nonceSet.size() == m_nonceQueue.size());
+ BOOST_ASSERT(m_nonceSet.size() <= CAPACITY);
+ }
+ return true;
+}
+
+} // namespace pit
+} // namespace nfd