util: in-memory storage

refs #1940

specification:
http://redmine.named-data.net/projects/ndn-cxx/wiki/InMemoryStorage

Change-Id: I7416d0dac4b4865ad931c3bf83180a043788405b

AUTHORS.md

@@ -26,3 +26,4 @@ in the library:
 * Lixia Zhang           <http://www.cs.ucla.edu/~lixia/home.html>
 * Jeff Burke            <http://remap.ucla.edu/jburke/>
 * Xiaoke Jiang          <http://netarchlab.tsinghua.edu.cn/~shock/>
+* Jiewen Tan            <alanwake@ucla.edu>

src/common.hpp

@@ -24,6 +24,18 @@
 
 #include "ndn-cxx-config.hpp"
 
+#ifdef NDN_CXX_HAVE_TESTS
+#define VIRTUAL_WITH_TESTS virtual
+#define PUBLIC_WITH_TESTS_ELSE_PROTECTED public
+#define PUBLIC_WITH_TESTS_ELSE_PRIVATE public
+#define PROTECTED_WITH_TESTS_ELSE_PRIVATE protected
+#else
+#define VIRTUAL_WITH_TESTS
+#define PUBLIC_WITH_TESTS_ELSE_PROTECTED protected
+#define PUBLIC_WITH_TESTS_ELSE_PRIVATE private
+#define PROTECTED_WITH_TESTS_ELSE_PRIVATE private
+#endif
+
 #include <stdint.h>
 #include <stddef.h>
 #include <unistd.h>

src/util/in-memory-storage-entry.cpp

@@ -0,0 +1,40 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2014 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#include "in-memory-storage-entry.hpp"
+
+namespace ndn {
+namespace util {
+
+void
+InMemoryStorageEntry::release()
+{
+  m_dataPacket.reset();
+}
+
+void
+InMemoryStorageEntry::setData(const Data& data)
+{
+  m_dataPacket = data.shared_from_this();
+}
+
+} // namespace util
+} // namespace ndn

src/util/in-memory-storage-entry.hpp

@@ -0,0 +1,81 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2014 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#ifndef NDN_UTIL_IN_MEMORY_STORAGE_ENTRY_HPP
+#define NDN_UTIL_IN_MEMORY_STORAGE_ENTRY_HPP
+
+#include "../common.hpp"
+#include "../interest.hpp"
+#include "../data.hpp"
+
+namespace ndn {
+namespace util {
+
+ /** @brief Represents an in-memory storage entry
+ */
+class InMemoryStorageEntry : noncopyable
+{
+public:
+  /** @brief Releases reference counts on shared objects
+   */
+  void
+  release();
+
+  /** @brief Returns the name of the Data packet stored in the in-memory storage entry
+   */
+  const Name&
+  getName() const
+  {
+    return m_dataPacket->getName();
+  }
+
+  /** @brief Returns the full name (including implicit digest) of the Data packet stored
+   *         in the in-memory storage entry
+   */
+  const Name&
+  getFullName() const
+  {
+    return m_dataPacket->getFullName();
+  }
+
+
+  /** @brief Returns the Data packet stored in the in-memory storage entry
+   */
+  const Data&
+  getData() const
+  {
+    return *m_dataPacket;
+  }
+
+
+  /** @brief Changes the content of in-memory storage entry
+   */
+  void
+  setData(const Data& data);
+
+private:
+  shared_ptr<const Data> m_dataPacket;
+};
+
+} // namespace util
+} // namespace ndn
+
+#endif // NDN_UTIL_IN_MEMORY_STORAGE_ENTRY_HPP

src/util/in-memory-storage-fifo.cpp

@@ -0,0 +1,65 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2014 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#include "in-memory-storage-fifo.hpp"
+
+namespace ndn {
+namespace util {
+
+InMemoryStorageFifo::InMemoryStorageFifo(size_t limit)
+  : InMemoryStorage(limit)
+{
+}
+
+InMemoryStorageFifo::~InMemoryStorageFifo()
+{
+}
+
+void
+InMemoryStorageFifo::afterInsert(InMemoryStorageEntry* entry)
+{
+  BOOST_ASSERT(m_cleanupIndex.size() <= size());
+  m_cleanupIndex.insert(entry);
+}
+
+bool
+InMemoryStorageFifo::evictItem()
+{
+  if (!m_cleanupIndex.get<byArrival>().empty()) {
+    CleanupIndex::index<byArrival>::type::iterator it = m_cleanupIndex.get<byArrival>().begin();
+    eraseImpl((*it)->getFullName());
+    m_cleanupIndex.get<byArrival>().erase(it);
+    return true;
+  }
+
+  return false;
+}
+
+void
+InMemoryStorageFifo::beforeErase(InMemoryStorageEntry* entry)
+{
+  CleanupIndex::index<byEntity>::type::iterator it = m_cleanupIndex.get<byEntity>().find(entry);
+  if (it != m_cleanupIndex.get<byEntity>().end())
+    m_cleanupIndex.get<byEntity>().erase(it);
+}
+
+} // namespace util
+} // namespace ndn

src/util/in-memory-storage-fifo.hpp

@@ -0,0 +1,93 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2014 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#ifndef NDN_UTIL_IN_MEMORY_STORAGE_FIFO_HPP
+#define NDN_UTIL_IN_MEMORY_STORAGE_FIFO_HPP
+
+#include "in-memory-storage.hpp"
+
+#include <boost/multi_index_container.hpp>
+#include <boost/multi_index/sequenced_index.hpp>
+#include <boost/multi_index/hashed_index.hpp>
+
+namespace ndn {
+namespace util {
+
+/** @brief Provides in-memory storage employing FIFO replacement policy, which is first in first
+ *  out.
+ */
+class InMemoryStorageFifo : public InMemoryStorage
+{
+public:
+  explicit
+  InMemoryStorageFifo(size_t limit = 10);
+
+  virtual
+  ~InMemoryStorageFifo();
+
+PUBLIC_WITH_TESTS_ELSE_PROTECTED:
+  /** @brief Removes one Data packet from in-memory storage based on FIFO
+   *  @return{ whether the Data was removed }
+   */
+  virtual bool
+  evictItem();
+
+  /** @brief Update the entry after a entry is successfully inserted, add it to the cleanupIndex
+   */
+  virtual void
+  afterInsert(InMemoryStorageEntry* entry);
+
+  /** @brief Update the entry or other data structures before a entry is successfully erased,
+   *  erase it from the cleanupIndex
+   */
+  virtual void
+  beforeErase(InMemoryStorageEntry* entry);
+
+private:
+  //multi_index_container to implement FIFO
+  class byArrival;
+  class byEntity;
+
+  typedef boost::multi_index_container<
+    InMemoryStorageEntry*,
+    boost::multi_index::indexed_by<
+
+      // by Entry itself
+      boost::multi_index::hashed_unique<
+        boost::multi_index::tag<byEntity>,
+        boost::multi_index::identity<InMemoryStorageEntry*>
+      >,
+
+      // by arrival (FIFO)
+      boost::multi_index::sequenced<
+        boost::multi_index::tag<byArrival>
+      >
+
+    >
+  > CleanupIndex;
+
+  CleanupIndex m_cleanupIndex;
+};
+
+} // namespace util
+} // namespace ndn
+
+#endif // NDN_UTIL_IN_MEMORY_STORAGE_FIFO_HPP

src/util/in-memory-storage-lfu.cpp

@@ -0,0 +1,75 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2014 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#include "in-memory-storage-lfu.hpp"
+
+namespace ndn {
+namespace util {
+
+InMemoryStorageLfu::InMemoryStorageLfu(size_t limit)
+  : InMemoryStorage(limit)
+{
+}
+
+InMemoryStorageLfu::~InMemoryStorageLfu()
+{
+}
+
+void
+InMemoryStorageLfu::afterInsert(InMemoryStorageEntry* entry)
+{
+  BOOST_ASSERT(m_cleanupIndex.size() <= size());
+  CleanupEntry cleanupEntry;
+  cleanupEntry.entry = entry;
+  cleanupEntry.frequency = 0;
+  m_cleanupIndex.insert(cleanupEntry);
+}
+
+bool
+InMemoryStorageLfu::evictItem()
+{
+  if (!m_cleanupIndex.get<byFrequency>().empty()) {
+    CleanupIndex::index<byFrequency>::type::iterator it = m_cleanupIndex.get<byFrequency>().begin();
+    eraseImpl(((*it).entry)->getFullName());
+    m_cleanupIndex.get<byFrequency>().erase(it);
+    return true;
+  }
+
+  return false;
+}
+
+void
+InMemoryStorageLfu::beforeErase(InMemoryStorageEntry* entry)
+{
+  CleanupIndex::index<byEntity>::type::iterator it = m_cleanupIndex.get<byEntity>().find(entry);
+  if (it != m_cleanupIndex.get<byEntity>().end())
+    m_cleanupIndex.get<byEntity>().erase(it);
+}
+
+void
+InMemoryStorageLfu::afterAccess(InMemoryStorageEntry* entry)
+{
+  CleanupIndex::index<byEntity>::type::iterator it = m_cleanupIndex.get<byEntity>().find(entry);
+  m_cleanupIndex.get<byEntity>().modify(it, &incrementFrequency);
+}
+
+} // namespace util
+} // namespace ndn

src/util/in-memory-storage-lfu.hpp

@@ -0,0 +1,121 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2014 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#ifndef NDN_UTIL_IN_MEMORY_STORAGE_LFU_HPP
+#define NDN_UTIL_IN_MEMORY_STORAGE_LFU_HPP
+
+#include "in-memory-storage.hpp"
+
+#include <boost/multi_index/member.hpp>
+#include <boost/multi_index_container.hpp>
+#include <boost/multi_index/ordered_index.hpp>
+#include <boost/multi_index/hashed_index.hpp>
+#include <boost/multi_index/identity.hpp>
+
+namespace ndn {
+namespace util {
+
+/** @brief Provides an in-memory storage with Least Frequently Used (LFU) replacement policy.
+ *  @note The frequency right now is usage count.
+ *  @sa https://en.wikipedia.org/w/index.php?title=Least_frequently_used&oldid=604542656
+ */
+class InMemoryStorageLfu : public InMemoryStorage
+{
+public:
+  explicit
+  InMemoryStorageLfu(size_t limit = 10);
+
+  virtual
+  ~InMemoryStorageLfu();
+
+PUBLIC_WITH_TESTS_ELSE_PROTECTED:
+  /** @brief Removes one Data packet from in-memory storage based on LFU, i.e. evict the least
+   *  frequently accessed Data packet
+   *  @return{ whether the Data was removed }
+   */
+  virtual bool
+  evictItem();
+
+  /** @brief Update the entry when the entry is returned by the find() function,
+   *  increment the frequency according to LFU
+   */
+  virtual void
+  afterAccess(InMemoryStorageEntry* entry);
+
+  /** @brief Update the entry after a entry is successfully inserted, add it to the cleanupIndex
+   */
+  virtual void
+  afterInsert(InMemoryStorageEntry* entry);
+
+  /** @brief Update the entry or other data structures before a entry is successfully erased,
+   *  erase it from the cleanupIndex
+   */
+  virtual void
+  beforeErase(InMemoryStorageEntry* entry);
+
+private:
+  //binds frequency and entry together
+  struct CleanupEntry
+  {
+    InMemoryStorageEntry* entry;
+    uint64_t frequency;//could potentially be overflowed
+  };
+
+  /** @brief Function to increment frequency of the entry in the CleanupEntry
+   */
+  static inline void
+  incrementFrequency(CleanupEntry& cleanupEntry)
+  {
+    ++cleanupEntry.frequency;
+  }
+
+private:
+  //multi_index_container to implement LFU
+  class byFrequency;
+  class byEntity;
+
+  typedef boost::multi_index_container<
+    CleanupEntry,
+    boost::multi_index::indexed_by<
+
+      // by Entry itself
+      boost::multi_index::hashed_unique<
+        boost::multi_index::tag<byEntity>,
+        boost::multi_index::member<CleanupEntry, InMemoryStorageEntry*, &CleanupEntry::entry>
+      >,
+
+      // by frequency (LFU)
+      boost::multi_index::ordered_non_unique<
+        boost::multi_index::tag<byFrequency>,
+        boost::multi_index::member<CleanupEntry, uint64_t, &CleanupEntry::frequency>,
+        std::less<uint64_t>
+      >
+
+    >
+  > CleanupIndex;
+
+  CleanupIndex m_cleanupIndex;
+};
+
+} // namespace util
+} // namespace ndn
+
+#endif // NDN_UTIL_IN_MEMORY_STORAGE_LFU_HPP

src/util/in-memory-storage-lru.cpp

@@ -0,0 +1,73 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2014 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#include "in-memory-storage-lru.hpp"
+
+namespace ndn {
+namespace util {
+
+InMemoryStorageLru::InMemoryStorageLru(size_t limit)
+  : InMemoryStorage(limit)
+{
+}
+
+InMemoryStorageLru::~InMemoryStorageLru()
+{
+}
+
+void
+InMemoryStorageLru::afterInsert(InMemoryStorageEntry* entry)
+{
+  BOOST_ASSERT(m_cleanupIndex.size() <= size());
+  InMemoryStorageEntry* ptr = entry;
+  m_cleanupIndex.insert(ptr);
+}
+
+bool
+InMemoryStorageLru::evictItem()
+{
+  if (!m_cleanupIndex.get<byUsedTime>().empty()) {
+    CleanupIndex::index<byUsedTime>::type::iterator it = m_cleanupIndex.get<byUsedTime>().begin();
+    eraseImpl((*it)->getFullName());
+    m_cleanupIndex.get<byUsedTime>().erase(it);
+    return true;
+  }
+
+  return false;
+}
+
+void
+InMemoryStorageLru::beforeErase(InMemoryStorageEntry* entry)
+{
+  CleanupIndex::index<byEntity>::type::iterator it = m_cleanupIndex.get<byEntity>().find(entry);
+  if (it != m_cleanupIndex.get<byEntity>().end())
+    m_cleanupIndex.get<byEntity>().erase(it);
+}
+
+void
+InMemoryStorageLru::afterAccess(InMemoryStorageEntry* entry)
+{
+  beforeErase(entry);
+  afterInsert(entry);
+}
+
+} // namespace util
+} // namespace ndn

src/util/in-memory-storage-lru.hpp

@@ -0,0 +1,102 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2014 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#ifndef NDN_UTIL_IN_MEMORY_STORAGE_LRU_HPP
+#define NDN_UTIL_IN_MEMORY_STORAGE_LRU_HPP
+
+#include "in-memory-storage.hpp"
+
+#include <boost/multi_index/member.hpp>
+#include <boost/multi_index_container.hpp>
+#include <boost/multi_index/sequenced_index.hpp>
+#include <boost/multi_index/hashed_index.hpp>
+#include <boost/multi_index/identity.hpp>
+
+namespace ndn {
+namespace util {
+
+/** @brief Provides in-memory storage employing LRU replacement policy, of which the least
+ *  recently used entry will be evict first.
+ */
+class InMemoryStorageLru : public InMemoryStorage
+{
+public:
+  explicit
+  InMemoryStorageLru(size_t limit = 10);
+
+  virtual
+  ~InMemoryStorageLru();
+
+PUBLIC_WITH_TESTS_ELSE_PROTECTED:
+  /** @brief Removes one Data packet from in-memory storage based on LRU, i.e. evict the least
+   *  recently accessed Data packet
+   *  @return{ whether the Data was removed }
+   */
+  virtual bool
+  evictItem();
+
+  /** @brief Update the entry when the entry is returned by the find() function,
+   *  update the last used time according to LRU
+   */
+  virtual void
+  afterAccess(InMemoryStorageEntry* entry);
+
+  /** @brief Update the entry after a entry is successfully inserted, add it to the cleanupIndex
+   */
+  virtual void
+  afterInsert(InMemoryStorageEntry* entry);
+
+  /** @brief Update the entry or other data structures before a entry is successfully erased,
+   *  erase it from the cleanupIndex
+   */
+  virtual void
+  beforeErase(InMemoryStorageEntry* entry);
+
+private:
+  //multi_index_container to implement LRU
+  class byUsedTime;
+  class byEntity;
+
+  typedef boost::multi_index_container<
+    InMemoryStorageEntry*,
+    boost::multi_index::indexed_by<
+
+      // by Entry itself
+      boost::multi_index::hashed_unique<
+        boost::multi_index::tag<byEntity>,
+        boost::multi_index::identity<InMemoryStorageEntry*>
+      >,
+
+      // by last used time (LRU)
+      boost::multi_index::sequenced<
+        boost::multi_index::tag<byUsedTime>
+      >
+
+    >
+  > CleanupIndex;
+
+  CleanupIndex m_cleanupIndex;
+};
+
+} // namespace util
+} // namespace ndn
+
+#endif // NDN_UTIL_IN_MEMORY_STORAGE_LRU_HPP

src/util/in-memory-storage-persistent.cpp

@@ -0,0 +1,43 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2014 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#include "in-memory-storage-persistent.hpp"
+
+namespace ndn {
+namespace util {
+
+InMemoryStoragePersistent::InMemoryStoragePersistent()
+  : InMemoryStorage()
+{
+}
+
+InMemoryStoragePersistent::~InMemoryStoragePersistent()
+{
+}
+
+bool
+InMemoryStoragePersistent::evictItem()
+{
+  return false;
+}
+
+} // namespace util
+} // namespace ndn

src/util/in-memory-storage-persistent.hpp

@@ -0,0 +1,56 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2014 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#ifndef NDN_UTIL_IN_MEMORY_STORAGE_PERSISTENT_HPP
+#define NDN_UTIL_IN_MEMORY_STORAGE_PERSISTENT_HPP
+
+#include "in-memory-storage.hpp"
+
+namespace ndn {
+namespace util {
+
+/** @brief Provides application cache with persistent storage, of which no replacement policy will
+ *  be employed. Entries will only be deleted by explicitly application control.
+ */
+class InMemoryStoragePersistent : public InMemoryStorage
+{
+public:
+  explicit
+  InMemoryStoragePersistent();
+
+  virtual
+  ~InMemoryStoragePersistent();
+
+PUBLIC_WITH_TESTS_ELSE_PROTECTED:
+  /** @brief Do nothing.
+   *
+   *  This storage is persistent, and does not support eviction.
+   *
+   *  @return false
+   */
+  virtual bool
+  evictItem();
+};
+
+} // namespace util
+} // namespace ndn
+
+#endif // NDN_UTIL_IN_MEMORY_STORAGE_PERSISTENT_HPP

src/util/in-memory-storage.cpp

@@ -0,0 +1,417 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2014 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#include "in-memory-storage.hpp"
+#include "in-memory-storage-entry.hpp"
+
+#include "crypto.hpp"
+
+#include "../security/signature-sha256-with-rsa.hpp"
+
+namespace ndn {
+namespace util {
+
+InMemoryStorage::const_iterator::const_iterator(const Data* ptr, const Cache* cache,
+                                                Cache::index<byFullName>::type::iterator it)
+  : m_ptr(ptr)
+  , m_cache(cache)
+  , m_it(it)
+{
+}
+
+InMemoryStorage::const_iterator&
+InMemoryStorage::const_iterator::operator++()
+{
+  m_it++;
+  if (m_it != m_cache->get<byFullName>().end()) {
+    m_ptr = &((*m_it)->getData());
+  }
+  else {
+    m_ptr = 0;
+  }
+
+  return *this;
+}
+
+InMemoryStorage::const_iterator
+InMemoryStorage::const_iterator::operator++(int)
+{
+  InMemoryStorage::const_iterator i(*this);
+  this->operator++();
+  return i;
+}
+
+const Data&
+InMemoryStorage::const_iterator::operator*()
+{
+  return *m_ptr;
+}
+
+const Data*
+InMemoryStorage::const_iterator::operator->()
+{
+  return m_ptr;
+}
+
+bool
+InMemoryStorage::const_iterator::operator==(const const_iterator& rhs)
+{
+  return m_it == rhs.m_it;
+}
+
+bool
+InMemoryStorage::const_iterator::operator!=(const const_iterator& rhs)
+{
+  return m_it != rhs.m_it;
+}
+
+InMemoryStorage::InMemoryStorage(size_t limit)
+  : m_limit(limit)
+  , m_nPackets(0)
+{
+  // TODO consider a more suitable initial value
+  m_capacity = 10;
+
+  if (limit != std::numeric_limits<size_t>::max() && m_capacity > m_limit) {
+    m_capacity = m_limit;
+  }
+
+  for (size_t i = 0; i < m_capacity; i++) {
+    m_freeEntries.push(new InMemoryStorageEntry());
+  }
+}
+
+InMemoryStorage::~InMemoryStorage()
+{
+  // evict all items from cache
+  Cache::iterator it = m_cache.begin();
+  while (it != m_cache.end()) {
+    freeEntry(it);
+    it++;
+  }
+
+  BOOST_ASSERT(m_freeEntries.size() == m_capacity);
+
+  while (!m_freeEntries.empty()) {
+    delete m_freeEntries.top();
+    m_freeEntries.pop();
+  }
+}
+
+void
+InMemoryStorage::setCapacity(size_t capacity)
+{
+  size_t oldCapacity = m_capacity;
+  m_capacity = capacity;
+
+  if (size() > m_capacity) {
+    ssize_t nAllowedFailures = size() - m_capacity;
+    while (size() > m_capacity) {
+      if (!evictItem() && --nAllowedFailures < 0) {
+        throw Error();
+      }
+    }
+  }
+
+  if (m_capacity >= oldCapacity) {
+    for (size_t i = oldCapacity; i < m_capacity; i++) {
+      m_freeEntries.push(new InMemoryStorageEntry());
+    }
+  }
+  else {
+    for (size_t i = oldCapacity; i > m_capacity; i--) {
+      delete m_freeEntries.top();
+      m_freeEntries.pop();
+    }
+  }
+
+  BOOST_ASSERT(size() + m_freeEntries.size() == m_capacity);
+}
+
+void
+InMemoryStorage::insert(const Data& data)
+{
+  //check if identical Data/Name already exists
+  Cache::index<byFullName>::type::iterator it = m_cache.get<byFullName>().find(data.getFullName());
+  if (it != m_cache.get<byFullName>().end())
+    return;
+
+  //if full, double the capacity
+  bool doesReachLimit = (getLimit() == getCapacity());
+  if (isFull() && !doesReachLimit) {
+    // note: This is incorrect if 2*capacity overflows, but memory should run out before that
+    size_t newCapacity = std::min(2 * getCapacity(), getLimit());
+    setCapacity(newCapacity);
+  }
+
+  //if full and reach limitation of the capacity, employ replacement policy
+  if (isFull() && doesReachLimit) {
+    evictItem();
+  }
+
+  //insert to cache
+  BOOST_ASSERT(m_freeEntries.size() > 0);
+  // take entry for the memory pool
+  InMemoryStorageEntry* entry = m_freeEntries.top();
+  m_freeEntries.pop();
+  m_nPackets++;
+  entry->setData(data);
+  m_cache.insert(entry);
+
+  //let derived class do something with the entry
+  afterInsert(entry);
+}
+
+shared_ptr<const Data>
+InMemoryStorage::find(const Name& name)
+{
+  Cache::index<byFullName>::type::iterator it = m_cache.get<byFullName>().lower_bound(name);
+
+  //if not found, return null
+  if (it == m_cache.get<byFullName>().end()) {
+    return shared_ptr<const Data>();
+  }
+
+  //if the given name is not the prefix of the lower_bound, return null
+  if (!name.isPrefixOf((*it)->getFullName())) {
+    return shared_ptr<const Data>();
+  }
+
+  afterAccess(*it);
+  return ((*it)->getData()).shared_from_this();
+}
+
+shared_ptr<const Data>
+InMemoryStorage::find(const Interest& interest)
+{
+  //if the interest contains implicit digest, it is possible to directly locate a packet.
+  Cache::index<byFullName>::type::iterator it = m_cache.get<byFullName>()
+                                                    .find(interest.getName());
+
+  //if a packet is located by its full name, it must be the packet to return.
+  if (it != m_cache.get<byFullName>().end()) {
+    return ((*it)->getData()).shared_from_this();
+  }
+
+  //if the packet is not discovered by last step, either the packet is not in the storage or
+  //the interest doesn't contains implicit digest.
+  it = m_cache.get<byFullName>().lower_bound(interest.getName());
+
+  if (it == m_cache.get<byFullName>().end()) {
+    return shared_ptr<const Data>();
+  }
+
+
+  //to locate the element that has a just smaller name than the interest's
+  if (it != m_cache.get<byFullName>().begin())
+    it--;
+
+  InMemoryStorageEntry* ret = selectChild(interest, it);
+  if (ret != 0) {
+    //let derived class do something with the entry
+    afterAccess(ret);
+    return ret->getData().shared_from_this();
+  }
+  else {
+    return shared_ptr<const Data>();
+  }
+}
+
+InMemoryStorageEntry*
+InMemoryStorage::selectChild(const Interest& interest,
+                             Cache::index<byFullName>::type::iterator startingPoint) const
+{
+  BOOST_ASSERT(startingPoint != m_cache.get<byFullName>().end());
+
+  if (startingPoint != m_cache.get<byFullName>().begin())
+    {
+      BOOST_ASSERT((*startingPoint)->getFullName() < interest.getName());
+    }
+
+  bool hasLeftmostSelector = (interest.getChildSelector() <= 0);
+  bool hasRightmostSelector = !hasLeftmostSelector;
+
+  if (hasLeftmostSelector)
+    {
+      if (interest.matchesData((*startingPoint)->getData()))
+        {
+          return *startingPoint;
+        }
+    }
+
+  //iterate to the right
+  Cache::index<byFullName>::type::iterator rightmost = startingPoint;
+  if (startingPoint != m_cache.get<byFullName>().end())
+    {
+      Cache::index<byFullName>::type::iterator rightmostCandidate = startingPoint;
+      Name currentChildPrefix("");
+
+      while (true)
+        {
+          ++rightmostCandidate;
+
+          bool isInBoundaries = (rightmostCandidate != m_cache.get<byFullName>().end());
+          bool isInPrefix = false;
+          if (isInBoundaries)
+            {
+              isInPrefix = interest.getName().isPrefixOf((*rightmostCandidate)->getFullName());
+            }
+
+          if (isInPrefix)
+            {
+              if (interest.matchesData((*rightmostCandidate)->getData()))
+                {
+                  if (hasLeftmostSelector)
+                    {
+                      return *rightmostCandidate;
+                    }
+
+                  if (hasRightmostSelector)
+                    {
+                      // get prefix which is one component longer than Interest name
+                      const Name& childPrefix = (*rightmostCandidate)->getFullName()
+                                                  .getPrefix(interest.getName().size() + 1);
+
+                      if (currentChildPrefix.empty() || (childPrefix != currentChildPrefix))
+                        {
+                          currentChildPrefix = childPrefix;
+                          rightmost = rightmostCandidate;
+                        }
+                    }
+                }
+            }
+          else
+            break;
+        }
+    }
+
+  if (rightmost != startingPoint)
+    {
+      return *rightmost;
+    }
+
+  if (hasRightmostSelector) // if rightmost was not found, try starting point
+    {
+      if (interest.matchesData((*startingPoint)->getData()))
+        {
+          return *startingPoint;
+        }
+    }
+
+  return 0;
+}
+
+void
+InMemoryStorage::freeEntry(Cache::index<byFullName>::type::iterator it) {
+  //push the *empty* entry into mem pool
+  (*it)->release();
+  m_freeEntries.push(*it);
+  m_nPackets--;
+  m_cache.get<byFullName>().erase(it);
+}
+
+void
+InMemoryStorage::erase(const Name& prefix, const bool isPrefix)
+{
+  if (isPrefix) {
+    Cache::index<byFullName>::type::iterator it = m_cache.get<byFullName>().lower_bound(prefix);
+
+    if (it == m_cache.get<byFullName>().end())
+      return;
+
+    while (it != m_cache.get<byFullName>().end() && prefix.isPrefixOf((*it)->getName())) {
+      //let derived class do something with the entry
+      beforeErase(*it);
+      freeEntry(it);
+      it++;
+    }
+  }
+  else {
+    Cache::index<byFullName>::type::iterator it = m_cache.get<byFullName>().find(prefix);
+
+    if (it == m_cache.get<byFullName>().end())
+      return;
+
+    //let derived class do something with the entry
+    beforeErase(*it);
+    freeEntry(it);
+  }
+
+  if (m_freeEntries.size() > (2 * size()))
+    setCapacity(getCapacity() / 2);
+}
+
+void
+InMemoryStorage::eraseImpl(const Name& name)
+{
+  Cache::index<byFullName>::type::iterator it = m_cache.get<byFullName>().find(name);
+
+  if (it == m_cache.get<byFullName>().end())
+    return;
+
+  freeEntry(it);
+}
+
+InMemoryStorage::const_iterator
+InMemoryStorage::begin() const
+{
+  Cache::index<byFullName>::type::iterator it = m_cache.get<byFullName>().begin();
+
+  return const_iterator(&((*it)->getData()), &m_cache, it);
+}
+
+InMemoryStorage::const_iterator
+InMemoryStorage::end() const
+{
+  Cache::index<byFullName>::type::iterator it = m_cache.get<byFullName>().end();
+
+  const Data* ptr = NULL;
+
+  return const_iterator(ptr, &m_cache, it);
+}
+
+void
+InMemoryStorage::afterInsert(InMemoryStorageEntry* entry)
+{
+}
+
+void
+InMemoryStorage::beforeErase(InMemoryStorageEntry* entry)
+{
+}
+
+void
+InMemoryStorage::afterAccess(InMemoryStorageEntry* entry)
+{
+}
+
+void
+InMemoryStorage::printCache(std::ostream& os) const
+{
+  //start from the upper layer towards bottom
+  const Cache::index<byFullName>::type& cacheIndex = m_cache.get<byFullName>();
+  for (Cache::index<byFullName>::type::iterator it = cacheIndex.begin();
+       it != cacheIndex.end(); it++)
+    os << (*it)->getFullName() << std::endl;
+}
+
+} // namespace util
+} // namespace ndn

src/util/in-memory-storage.hpp

@@ -0,0 +1,311 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2014 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#ifndef NDN_UTIL_IN_MEMORY_STORAGE_HPP
+#define NDN_UTIL_IN_MEMORY_STORAGE_HPP
+
+#include "../common.hpp"
+#include "../interest.hpp"
+#include "../data.hpp"
+
+#include "in-memory-storage-entry.hpp"
+
+#include <boost/multi_index/member.hpp>
+#include <boost/multi_index_container.hpp>
+#include <boost/multi_index/ordered_index.hpp>
+#include <boost/multi_index/sequenced_index.hpp>
+#include <boost/multi_index/identity.hpp>
+#include <boost/multi_index/mem_fun.hpp>
+
+#include <stack>
+#include <iterator>
+#include <stdexcept>
+
+namespace ndn {
+namespace util {
+
+/** @brief Represents in-memory storage
+ */
+class InMemoryStorage : noncopyable
+{
+public:
+  //multi_index_container to implement storage
+  class byFullName;
+
+  typedef boost::multi_index_container<
+    InMemoryStorageEntry*,
+    boost::multi_index::indexed_by<
+
+      // by Full Name
+      boost::multi_index::ordered_unique<
+        boost::multi_index::tag<byFullName>,
+        boost::multi_index::const_mem_fun<InMemoryStorageEntry, const Name&,
+                                          &InMemoryStorageEntry::getFullName>,
+        std::less<Name>
+      >
+
+    >
+  > Cache;
+
+  /** @brief Represents a self-defined const_iterator for the in-memory storage
+   *
+   *  @note Don't try to instantiate this class directly, use InMemoryStorage::begin() instead.
+   */
+  class const_iterator : public std::iterator<std::input_iterator_tag, const Data>
+  {
+  public:
+    const_iterator(const Data* ptr, const Cache* cache,
+                   Cache::index<byFullName>::type::iterator it);
+
+    const_iterator&
+    operator++();
+
+    const_iterator
+    operator++(int);
+
+    const Data&
+    operator*();
+
+    const Data*
+    operator->();
+
+    bool
+    operator==(const const_iterator& rhs);
+
+    bool
+    operator!=(const const_iterator& rhs);
+
+  private:
+    const Data* m_ptr;
+    const Cache* m_cache;
+    Cache::index<byFullName>::type::iterator m_it;
+  };
+
+  /** @brief Represents an error might be thrown during reduce the current capacity of the
+   *  in-memory storage through function setCapacity(size_t nMaxPackets).
+   */
+  class Error : public std::runtime_error
+  {
+  public:
+    Error() : std::runtime_error("Cannot reduce the capacity of the in-memory storage!")
+    {
+    }
+  };
+
+  explicit
+  InMemoryStorage(size_t limit = std::numeric_limits<size_t>::max());
+
+  /** @note Please make sure to implement it to free m_freeEntries and evict
+    * all items in the derived class for anybody who wishes to inherit this class
+    */
+  virtual
+  ~InMemoryStorage();
+
+  /** @brief Inserts a Data packet
+   *
+   *  @note Packets are considered duplicate if the name with implicit digest matches.
+   *  The new Data packet with the identical name, but a different payload
+   *  will be placed in the in-memory storage.
+   *
+   *  @note It will invoke afterInsert(shared_ptr<InMemoryStorageEntry>).
+   */
+  void
+  insert(const Data& data);
+
+  /** @brief Finds the best match Data for an Interest
+   *
+   *  @note It will invoke afterAccess(shared_ptr<InMemoryStorageEntry>).
+   *  As currently it is impossible to determine whether a Name contains implicit digest or not,
+   *  therefore this find function is not able to locate a packet according to an interest(
+   *  including implicit digest) whose name is not the full name of the data matching the
+   *  implicit digest.
+   *
+   *  @return{ the best match, if any; otherwise a null shared_ptr }
+   */
+  shared_ptr<const Data>
+  find(const Interest& interest);
+
+  /** @brief Finds the best match Data for a Name with or without
+   *  the implicit digest.
+   *
+   *  If packets with the same name but different digests exist
+   *  and the Name supplied is the one without implicit digest, a packet
+   *  will be arbitrarily chosen to return.
+   *
+   *  @note It will invoke afterAccess(shared_ptr<InMemoryStorageEntry>).
+   *
+   *  @return{ the one matched the Name; otherwise a null shared_ptr }
+   */
+  shared_ptr<const Data>
+  find(const Name& name);
+
+  /** @brief Deletes in-memory storage entry by prefix by default.
+   *  @param[in] isPrefix If it is clear, the function will only delete the
+   *  entry completely matched with the prefix according to canonical ordering.
+   *  For this case, user should substitute the prefix with full name.
+   *
+   *  @note Please do not use this function directly in any derived class to erase
+   *  entry in the cache, use eraseHelper instead.
+   *  @note It will invoke beforeErase(shared_ptr<InMemoryStorageEntry>).
+   */
+  void
+  erase(const Name& prefix, const bool isPrefix = true);
+
+  /** @return{ maximum number of packets that can be allowed to store in in-memory storage }
+   */
+  size_t
+  getLimit() const
+  {
+    return m_limit;
+  }
+
+  /** @return{ number of packets stored in in-memory storage }
+   */
+  size_t
+  size() const
+  {
+    return m_nPackets;
+  }
+
+  /** @brief Returns begin iterator of the in-memory storage ordering by
+   *  name with digest
+   *
+   *  @return{ const_iterator pointing to the beginning of the m_cache }
+   */
+  InMemoryStorage::const_iterator
+  begin() const;
+
+  /** @brief Returns end iterator of the in-memory storage ordering by
+   *  name with digest
+   *
+   *  @return{ const_iterator pointing to the end of the m_cache }
+   */
+  InMemoryStorage::const_iterator
+  end() const;
+
+PUBLIC_WITH_TESTS_ELSE_PROTECTED:
+  /** @brief Update the entry when the entry is returned by the find() function
+   *  according to derived class implemented replacement policy
+   */
+  virtual void
+  afterAccess(InMemoryStorageEntry* entry);
+
+  /** @brief Update the entry or other data structures
+   *  after a entry is successfully inserted
+   *  according to derived class implemented replacement policy
+   */
+  virtual void
+  afterInsert(InMemoryStorageEntry* entry);
+
+  /** @brief Update the entry or other data structures
+   *  before a entry is successfully erased
+   *  according to derived class implemented replacement policy
+   */
+  virtual void
+  beforeErase(InMemoryStorageEntry* entry);
+
+  /** @brief Removes one Data packet from in-memory storage based on
+   *  derived class implemented replacement policy
+   *
+   *  Please do not use this function directly in any derived class to erase
+   *  entry in the cache, use eraseHelper instead.
+   *  @return{ whether the Data was removed }
+   */
+  virtual bool
+  evictItem() = 0;
+
+PUBLIC_WITH_TESTS_ELSE_PROTECTED:
+  /** @brief sets current capacity of in-memory storage (in packets)
+   */
+  void
+  setCapacity(size_t nMaxPackets);
+
+  /** @brief returns current capacity of in-memory storage (in packets)
+   *  @return{ number of packets that can be stored in application cache }
+   */
+  size_t
+  getCapacity() const
+  {
+    return m_capacity;
+  }
+
+  /** @brief returns true if the in-memory storage uses up the current capacity, false otherwise
+   */
+  bool
+  isFull() const
+  {
+    return size() >= m_capacity;
+  }
+
+  /** @brief deletes in-memory storage entries by the Name with implicit digest.
+   *
+   *  This is the function one should use to erase entry in the cache
+   *  in derived class.
+   *  It won't invoke beforeErase(shared_ptr<Entry>).
+   */
+  void
+  eraseImpl(const Name& name);
+
+  /** @brief Prints contents of the in-memory storage
+   */
+  void
+  printCache(std::ostream& os) const;
+
+PUBLIC_WITH_TESTS_ELSE_PRIVATE:
+  /** @brief free in-memory storage entries by an iterator pointing to that entry.
+    */
+  void
+  freeEntry(Cache::index<byFullName>::type::iterator it);
+
+  /** @brief Implements child selector (leftmost, rightmost, undeclared).
+   *  Operates on the first layer of a skip list.
+   *
+   *  startingPoint must be less than Interest Name.
+   *  startingPoint can be equal to Interest Name only
+   *  when the item is in the begin() position.
+   *
+   *  Iterates toward greater Names, terminates when application cache entry falls out of Interest
+   *  prefix. When childSelector = leftmost, returns first application cache entry that satisfies
+   *  other selectors. When childSelector = rightmost, it goes till the end, and returns application
+   *  cache entry that satisfies other selectors. Returned application cache entry is the leftmost
+   *  child of the rightmost child.
+   *  @return{ the best match, if any; otherwise 0 }
+   */
+  InMemoryStorageEntry*
+  selectChild(const Interest& interest,
+              Cache::index<byFullName>::type::iterator startingPoint) const;
+
+private:
+  Cache m_cache;
+  /// user defined maximum capacity of the in-memory storage in packets
+  size_t m_limit;
+  /// current capacity of the in-memory storage in packets
+  size_t m_capacity;
+  /// current number of packets in in-memory storage
+  size_t m_nPackets;
+  /// memory pool
+  std::stack<InMemoryStorageEntry*> m_freeEntries;
+};
+
+} // namespace util
+} // namespace ndn
+
+#endif // NDN_UTIL_IN_MEMORY_STORAGE_HPP

tests/unit-tests/test-make-interest-data.hpp

@@ -0,0 +1,67 @@
+/* -*- 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
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ **/
+
+#ifndef NDN_TESTS_UNIT_TESTS_MAKE_INTEREST_DATA_HPP
+#define NDN_TESTS_UNIT_TESTS_MAKE_INTEREST_DATA_HPP
+
+#include "boost-test.hpp"
+
+#include "security/key-chain.hpp"
+
+namespace ndn {
+namespace util {
+
+inline shared_ptr<Interest>
+makeInterest(const Name& name)
+{
+  return make_shared<Interest>(name);
+}
+
+inline shared_ptr<Data>
+signData(const shared_ptr<Data>& data)
+{
+  ndn::SignatureSha256WithRsa fakeSignature;
+  fakeSignature.setValue(ndn::dataBlock(tlv::SignatureValue,
+                                        reinterpret_cast<const uint8_t*>(0), 0));
+  data->setSignature(fakeSignature);
+  data->wireEncode();
+
+  return data;
+}
+
+inline shared_ptr<Data>
+makeData(const Name& name)
+{
+  shared_ptr<Data> data = make_shared<Data>(name);
+
+  return signData(data);
+}
+
+} // namespace util
+
+} // namespace ndn
+
+#endif // NDN_TESTS_UNIT_TESTS_MAKE_INTEREST_DATA_HPP

tests/unit-tests/util/test-in-memory-storage-fifo.cpp

@@ -0,0 +1,77 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2014 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#include "util/in-memory-storage-fifo.hpp"
+#include "security/key-chain.hpp"
+
+#include "boost-test.hpp"
+#include "../test-make-interest-data.hpp"
+
+namespace ndn {
+namespace util {
+
+BOOST_AUTO_TEST_SUITE(UtilInMemoryStorageFifo)
+
+BOOST_AUTO_TEST_CASE(ArrivalQueue)
+{
+  InMemoryStorageFifo ims;
+
+  ims.insert(*makeData("/1"));
+  ims.insert(*makeData("/2"));
+  ims.insert(*makeData("/3"));
+
+  ims.evictItem();
+  BOOST_CHECK_EQUAL(ims.size(), 2);
+
+  shared_ptr<Interest> interest = makeInterest("/1");
+  shared_ptr<const Data> found = ims.find(*interest);
+  BOOST_CHECK(!static_cast<bool>(found));
+}
+
+BOOST_AUTO_TEST_CASE(ArrivalQueue2)
+{
+  InMemoryStorageFifo ims;
+
+  ims.insert(*makeData("/1"));
+  ims.insert(*makeData("/2"));
+  ims.insert(*makeData("/3"));
+
+  ims.evictItem();
+  BOOST_CHECK_EQUAL(ims.size(), 2);
+
+  shared_ptr<Interest> interest1 = makeInterest("/1");
+  shared_ptr<const Data> found1 = ims.find(*interest1);
+  BOOST_CHECK(!static_cast<bool>(found1));
+
+  ims.insert(*makeData("/4"));
+
+  ims.evictItem();
+  BOOST_CHECK_EQUAL(ims.size(), 2);
+
+  shared_ptr<Interest> interest2 = makeInterest("/2");
+  shared_ptr<const Data> found2 = ims.find(*interest2);
+  BOOST_CHECK(!static_cast<bool>(found2));
+}
+
+BOOST_AUTO_TEST_SUITE_END()
+
+} // namespace util
+} // namespace ndn

tests/unit-tests/util/test-in-memory-storage-lfu.cpp

@@ -0,0 +1,132 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2014 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#include "util/in-memory-storage-lfu.hpp"
+#include "security/key-chain.hpp"
+
+#include "boost-test.hpp"
+#include "../test-make-interest-data.hpp"
+
+namespace ndn {
+namespace util {
+
+BOOST_AUTO_TEST_SUITE(UtilInMemoryStorageLfu)
+
+BOOST_AUTO_TEST_CASE(FrequencyQueue)
+{
+  InMemoryStorageLfu ims;
+
+  Name name1("/insert/1");
+  shared_ptr<Data> data1 = makeData(name1);
+  ims.insert(*data1);
+
+  Name name2("/insert/2");
+  shared_ptr<Data> data2 = makeData(name2);
+  ims.insert(*data2);
+
+  Name name3("/insert/3");
+  shared_ptr<Data> data3 = makeData(name3);
+  ims.insert(*data3);
+
+  shared_ptr<Interest> interest1 = makeInterest(name1);
+  shared_ptr<Interest> interest2 = makeInterest(name2);
+  shared_ptr<Interest> interest3 = makeInterest(name3);
+
+  ims.find(*interest1);
+  ims.find(*interest2);
+  ims.find(*interest3);
+  ims.find(*interest1);
+  ims.find(*interest3);
+  ims.find(*interest3);
+
+  ims.evictItem();
+  BOOST_CHECK_EQUAL(ims.size(), 2);
+
+  shared_ptr<const Data> found2 = ims.find(*interest2);
+  BOOST_CHECK(!static_cast<bool>(found2));
+
+  shared_ptr<const Data> found1 = ims.find(*interest1);
+  BOOST_CHECK_EQUAL(found1->getName(), name1);
+  shared_ptr<const Data> found3 = ims.find(*interest3);
+  BOOST_CHECK_EQUAL(found3->getName(), name3);
+}
+
+BOOST_AUTO_TEST_CASE(FrequencyQueue2)
+{
+  InMemoryStorageLfu ims;
+
+  Name name1("/insert/1");
+  shared_ptr<Data> data1 = makeData(name1);
+  ims.insert(*data1);
+
+  Name name2("/insert/2");
+  shared_ptr<Data> data2 = makeData(name2);
+  ims.insert(*data2);
+
+  Name name3("/insert/3");
+  shared_ptr<Data> data3 = makeData(name3);
+  ims.insert(*data3);
+
+  shared_ptr<Interest> interest1 = makeInterest(name1);
+  shared_ptr<Interest> interest2 = makeInterest(name2);
+  shared_ptr<Interest> interest3 = makeInterest(name3);
+
+  ims.find(*interest1);
+  ims.find(*interest2);
+  ims.find(*interest3);
+  ims.find(*interest1);
+  ims.find(*interest3);
+  ims.find(*interest3);
+
+  ims.evictItem();
+  BOOST_CHECK_EQUAL(ims.size(), 2);
+
+  shared_ptr<const Data> found2 = ims.find(*interest2);
+  BOOST_CHECK(!static_cast<bool>(found2));
+
+  shared_ptr<const Data> found1 = ims.find(*interest1);
+  BOOST_CHECK_EQUAL(found1->getName(), name1);
+  shared_ptr<const Data> found3 = ims.find(*interest3);
+  BOOST_CHECK_EQUAL(found3->getName(), name3);
+
+  Name name4("/insert/4");
+  shared_ptr<Data> data4 = makeData(name4);
+  ims.insert(*data4);
+
+  shared_ptr<Interest> interest4 = makeInterest(name4);
+  ims.find(*interest4);
+
+  ims.evictItem();
+  BOOST_CHECK_EQUAL(ims.size(), 2);
+
+  shared_ptr<const Data> found4 = ims.find(*interest4);
+  BOOST_CHECK(!static_cast<bool>(found4));
+
+  found1 = ims.find(*interest1);
+  BOOST_CHECK_EQUAL(found1->getName(), name1);
+  found3 = ims.find(*interest3);
+  BOOST_CHECK_EQUAL(found3->getName(), name3);
+}
+
+BOOST_AUTO_TEST_SUITE_END()
+
+} // namesapce util
+} // namespace ndn

tests/unit-tests/util/test-in-memory-storage-lru.cpp

@@ -0,0 +1,134 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2014 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#include "util/in-memory-storage-lru.hpp"
+#include "security/key-chain.hpp"
+
+#include "boost-test.hpp"
+#include "../test-make-interest-data.hpp"
+
+namespace ndn {
+namespace util {
+
+BOOST_AUTO_TEST_SUITE(UtilInMemoryStorageLru)
+
+BOOST_AUTO_TEST_CASE(UsedTimeQueue)
+{
+  InMemoryStorageLru ims;
+
+  Name name1("/insert/1");
+  shared_ptr<Data> data1 = makeData(name1);
+  ims.insert(*data1);
+
+  Name name2("/insert/2");
+  shared_ptr<Data> data2 = makeData(name2);
+  ims.insert(*data2);
+
+  Name name3("/insert/3");
+  shared_ptr<Data> data3 = makeData(name3);
+  ims.insert(*data3);
+
+  shared_ptr<Interest> interest1 = makeInterest(name1);
+  shared_ptr<Interest> interest2 = makeInterest(name2);
+  shared_ptr<Interest> interest3 = makeInterest(name3);
+
+  ims.find(*interest1);
+  ims.find(*interest2);
+  ims.find(*interest3);
+  ims.find(*interest1);
+  ims.find(*interest3);
+  ims.find(*interest3);
+
+  ims.evictItem();
+  BOOST_CHECK_EQUAL(ims.size(), 2);
+
+  shared_ptr<const Data> found2 = ims.find(*interest2);
+  BOOST_CHECK(!static_cast<bool>(found2));
+
+  shared_ptr<const Data> found1 = ims.find(*interest1);
+  BOOST_CHECK_EQUAL(found1->getName(), name1);
+  shared_ptr<const Data> found3 = ims.find(*interest3);
+  BOOST_CHECK_EQUAL(found3->getName(), name3);
+}
+
+BOOST_AUTO_TEST_CASE(UsedTimeQueue2)
+{
+  InMemoryStorageLru ims;
+
+  Name name1("/insert/1");
+  shared_ptr<Data> data = makeData(name1);
+  ims.insert(*data);
+
+  Name name2("/insert/2");
+  shared_ptr<Data> data2 = makeData(name2);
+  ims.insert(*data2);
+
+  Name name3("/insert/3");
+  shared_ptr<Data> data3 = makeData(name3);
+  ims.insert(*data3);
+
+  shared_ptr<Interest> interest1 = makeInterest(name1);
+  shared_ptr<Interest> interest2 = makeInterest(name2);
+  shared_ptr<Interest> interest3 = makeInterest(name3);
+
+  ims.find(*interest1);
+  ims.find(*interest2);
+  ims.find(*interest3);
+  ims.find(*interest1);
+  ims.find(*interest3);
+  ims.find(*interest3);
+
+  ims.evictItem();
+  BOOST_CHECK_EQUAL(ims.size(), 2);
+
+  shared_ptr<const Data> found2 = ims.find(*interest2);
+  BOOST_CHECK(!static_cast<bool>(found2));
+
+  shared_ptr<const Data> found1 = ims.find(*interest1);
+  BOOST_CHECK_EQUAL(found1->getName(), name1);
+  shared_ptr<const Data> found3 = ims.find(*interest3);
+  BOOST_CHECK_EQUAL(found3->getName(), name3);
+
+  Name name4("/insert/4");
+  shared_ptr<Data> data4 = makeData(name4);
+  ims.insert(*data4);
+
+  shared_ptr<Interest> interest4 = makeInterest(name4);
+  ims.find(*interest4);
+  ims.find(*interest1);
+  ims.find(*interest3);
+
+  ims.evictItem();
+  BOOST_CHECK_EQUAL(ims.size(), 2);
+
+  shared_ptr<const Data> found4 = ims.find(*interest4);
+  BOOST_CHECK(!static_cast<bool>(found4));
+
+  found1 = ims.find(*interest1);
+  BOOST_CHECK_EQUAL(found1->getName(), name1);
+  found3 = ims.find(*interest3);
+  BOOST_CHECK_EQUAL(found3->getName(), name3);
+}
+
+BOOST_AUTO_TEST_SUITE_END()
+
+} // namespace util
+} // namespace ndn

tests/unit-tests/util/test-in-memory-storage-persistent.cpp

@@ -0,0 +1,62 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2013-2014 Regents of the University of California.
+ *
+ * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
+ *
+ * ndn-cxx library is free software: you can redistribute it and/or modify it under the
+ * terms of the GNU Lesser General Public License as published by the Free Software
+ * Foundation, either version 3 of the License, or (at your option) any later version.
+ *
+ * ndn-cxx library 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 Lesser General Public License for more details.
+ *
+ * You should have received copies of the GNU General Public License and GNU Lesser
+ * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
+ */
+
+#include "util/in-memory-storage-persistent.hpp"
+#include "security/key-chain.hpp"
+
+#include "boost-test.hpp"
+#include "../test-make-interest-data.hpp"
+
+namespace ndn {
+namespace util {
+
+BOOST_AUTO_TEST_SUITE(UtilInMemoryStoragePersistent)
+
+BOOST_AUTO_TEST_CASE(GetLimit)
+{
+  InMemoryStoragePersistent ims;
+
+  BOOST_CHECK_EQUAL(ims.getLimit(), -1);
+}
+
+BOOST_AUTO_TEST_CASE(InsertAndDouble)
+{
+  InMemoryStoragePersistent ims;
+
+  for(int i = 0; i < 11; i++) {
+    std::ostringstream convert;
+    convert << i;
+    Name name("/" + convert.str());
+    shared_ptr<Data> data = makeData(name);
+    data->setFreshnessPeriod(time::milliseconds(5000));
+    signData(data);
+    ims.insert(*data);
+  }
+
+  BOOST_CHECK_EQUAL(ims.size(), 11);
+
+  BOOST_CHECK_EQUAL(ims.getCapacity(), 20);
+}
+
+BOOST_AUTO_TEST_SUITE_END()
+
+} // namespace util
+} // namespace ndn