daemon/table/cs.hpp

/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2014-2018,  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/>.
 */

/** \file
 *
 *  \brief implements the ContentStore
 *
 *  This ContentStore implementation consists of two data structures,
 *  a Table, and a set of cleanup queues.
 *
 *  The Table is a container (std::set) sorted by full Names of stored Data packets.
 *  Data packets are wrapped in Entry objects.
 *  Each Entry contain the Data packet itself,
 *  and a few addition attributes such as the staleness of the Data packet.
 *
 *  The cleanup queues are three doubly linked lists which stores Table iterators.
 *  The three queues keep track of unsolicited, stale, and fresh Data packet, respectively.
 *  Table iterator is placed into, removed from, and moved between suitable queues
 *  whenever an Entry is added, removed, or has other attribute changes.
 *  The Table iterator of an Entry should be in exactly one queue at any moment.
 *  Within each queue, the iterators are kept in first-in-first-out order.
 *  Eviction procedure exhausts the first queue before moving onto the next queue,
 *  in the order of unsolicited, stale, and fresh queue.
 */

#ifndef NFD_DAEMON_TABLE_CS_HPP
#define NFD_DAEMON_TABLE_CS_HPP

#include "cs-policy.hpp"
#include "cs-internal.hpp"
#include "cs-entry-impl.hpp"
#include <ndn-cxx/util/signal.hpp>
#include <boost/iterator/transform_iterator.hpp>

namespace nfd {
namespace cs {

/** \brief represents the ContentStore
 */
class Cs : noncopyable
{
public:
  explicit
  Cs(size_t nMaxPackets = 10);

  /** \brief inserts a Data packet
   */
  void
  insert(const Data& data, bool isUnsolicited = false);

  typedef std::function<void(const Interest&, const Data& data)> HitCallback;
  typedef std::function<void(const Interest&)> MissCallback;

  /** \brief finds the best matching Data packet
   *  \param interest the Interest for lookup
   *  \param hitCallback a callback if a match is found; must not be empty
   *  \param missCallback a callback if there's no match; must not be empty
   *  \note A lookup invokes either callback exactly once.
   *        The callback may be invoked either before or after find() returns
   */
  void
  find(const Interest& interest,
       const HitCallback& hitCallback,
       const MissCallback& missCallback) const;

  /** \brief get number of stored packets
   */
  size_t
  size() const
  {
    return m_table.size();
  }

public: // configuration
  /** \brief get capacity (in number of packets)
   */
  size_t
  getLimit() const
  {
    return m_policy->getLimit();
  }

  /** \brief change capacity (in number of packets)
   */
  void
  setLimit(size_t nMaxPackets)
  {
    return m_policy->setLimit(nMaxPackets);
  }

  /** \brief get replacement policy
   */
  Policy*
  getPolicy() const
  {
    return m_policy.get();
  }

  /** \brief change replacement policy
   *  \pre size() == 0
   */
  void
  setPolicy(unique_ptr<Policy> policy);

  /** \brief get CS_ENABLE_ADMIT flag
   *  \sa https://redmine.named-data.net/projects/nfd/wiki/CsMgmt#Update-config
   */
  bool
  shouldAdmit() const
  {
    return m_shouldAdmit;
  }

  /** \brief set CS_ENABLE_ADMIT flag
   *  \sa https://redmine.named-data.net/projects/nfd/wiki/CsMgmt#Update-config
   */
  void
  enableAdmit(bool shouldAdmit);

  /** \brief get CS_ENABLE_SERVE flag
   *  \sa https://redmine.named-data.net/projects/nfd/wiki/CsMgmt#Update-config
   */
  bool
  shouldServe() const
  {
    return m_shouldServe;
  }

  /** \brief set CS_ENABLE_SERVE flag
   *  \sa https://redmine.named-data.net/projects/nfd/wiki/CsMgmt#Update-config
   */
  void
  enableServe(bool shouldServe);

public: // enumeration
  struct EntryFromEntryImpl
  {
    typedef const Entry& result_type;

    const Entry&
    operator()(const EntryImpl& entry) const
    {
      return entry;
    }
  };

  /** \brief ContentStore iterator (public API)
   */
  typedef boost::transform_iterator<EntryFromEntryImpl, iterator, const Entry&> const_iterator;

  const_iterator
  begin() const
  {
    return boost::make_transform_iterator(m_table.begin(), EntryFromEntryImpl());
  }

  const_iterator
  end() const
  {
    return boost::make_transform_iterator(m_table.end(), EntryFromEntryImpl());
  }

private: // find
  /** \brief find leftmost match in [first,last)
   *  \return the leftmost match, or last if not found
   */
  iterator
  findLeftmost(const Interest& interest, iterator left, iterator right) const;

  /** \brief find rightmost match in [first,last)
   *  \return the rightmost match, or last if not found
   */
  iterator
  findRightmost(const Interest& interest, iterator first, iterator last) const;

  /** \brief find rightmost match among entries with exact Names in [first,last)
   *  \return the rightmost match, or last if not found
   */
  iterator
  findRightmostAmongExact(const Interest& interest, iterator first, iterator last) const;

  void
  setPolicyImpl(unique_ptr<Policy> policy);

PUBLIC_WITH_TESTS_ELSE_PRIVATE:
  void
  dump();

private:
  Table m_table;
  unique_ptr<Policy> m_policy;
  signal::ScopedConnection m_beforeEvictConnection;

  bool m_shouldAdmit; ///< if false, no Data will be admitted
  bool m_shouldServe; ///< if false, all lookups will miss
};

} // namespace cs

using cs::Cs;

} // namespace nfd

#endif // NFD_DAEMON_TABLE_CS_HPP