table: add CS policy LRU

Change-Id: Ief9e3d993782730069cedc8a99b8011d5d18ce7c
refs: #2219
diff --git a/daemon/table/cs-policy-lru.cpp b/daemon/table/cs-policy-lru.cpp
new file mode 100644
index 0000000..dad467d
--- /dev/null
+++ b/daemon/table/cs-policy-lru.cpp
@@ -0,0 +1,94 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014-2015,  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 "cs-policy-lru.hpp"
+#include "cs.hpp"
+#include <ndn-cxx/util/signal.hpp>
+
+namespace nfd {
+namespace cs {
+namespace lru {
+
+const std::string LruPolicy::POLICY_NAME = "lru";
+
+LruPolicy::LruPolicy()
+  : Policy(POLICY_NAME)
+{
+}
+
+void
+LruPolicy::doAfterInsert(iterator i)
+{
+  this->insertToQueue(i, true);
+  this->evictEntries();
+}
+
+void
+LruPolicy::doAfterRefresh(iterator i)
+{
+  this->insertToQueue(i, false);
+}
+
+void
+LruPolicy::doBeforeErase(iterator i)
+{
+  m_queue.get<1>().erase(i);
+}
+
+void
+LruPolicy::doBeforeUse(iterator i)
+{
+  this->insertToQueue(i, false);
+}
+
+void
+LruPolicy::evictEntries()
+{
+  BOOST_ASSERT(this->getCs() != nullptr);
+  while (this->getCs()->size() > this->getLimit()) {
+    BOOST_ASSERT(!m_queue.empty());
+    iterator i = m_queue.front();
+    m_queue.pop_front();
+    this->emitSignal(beforeEvict, i);
+  }
+}
+
+void
+LruPolicy::insertToQueue(iterator i, bool isNewEntry)
+{
+  Queue::iterator it;
+  bool isNew = false;
+  // push_back only if iterator i does not exist
+  std::tie(it, isNew) = m_queue.push_back(i);
+
+  BOOST_ASSERT(isNew == isNewEntry);
+  if (!isNewEntry) {
+    m_queue.relocate(m_queue.end(), it);
+  }
+}
+
+} // namespace lru
+} // namespace cs
+} // namespace nfd