daemon/fw/strategy.hpp - ndnSIM/NFD - Gitiles

 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /**
  * Copyright (c) 2014-2016,  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/>.
  */

 #ifndef NFD_DAEMON_FW_STRATEGY_HPP
 #define NFD_DAEMON_FW_STRATEGY_HPP

 #include "forwarder.hpp"
 #include "table/measurements-accessor.hpp"

 namespace nfd {
 namespace fw {

 /** \brief represents a forwarding strategy
  */
 class Strategy : noncopyable
 {
 public: // registry
   /** \brief register a strategy type
    *  \tparam S subclass of Strategy
    *  \param strategyName versioned strategy name
    *  \note It is permitted to register the same strategy type under multiple names,
    *        which is useful in tests and for creating aliases.
    */
   template<typename S>
   static void
   registerType(const Name& strategyName = S::getStrategyName())
   {
     Registry& registry = getRegistry();
     BOOST_ASSERT(registry.count(strategyName) == 0);
     registry[strategyName] = &make_unique<S, Forwarder&, const Name&>;
   }

   /** \return whether a strategy instance can be created from \p strategyName
    *  \param strategyName strategy name, may contain version
    *  \todo #3868 may contain parameters
    *  \note This function finds a strategy type using same rules as \p create ,
    *        but does not attempt to construct an instance.
    */
   static bool
   canCreate(const Name& strategyName);

   /** \return a strategy instance created from \p strategyName,
    *  \retval nullptr if !canCreate(strategyName)
    *  \todo #3868 throw std::invalid_argument strategy type constructor
    *              does not accept specified version or parameters
    */
   static unique_ptr<Strategy>
   create(const Name& strategyName, Forwarder& forwarder);

   /** \return registered versioned strategy names
    */
   static std::set<Name>
   listRegistered();

 public: // constructor, destructor, strategy name
   /** \brief construct a strategy instance
    *  \param forwarder a reference to the Forwarder, used to enable actions and accessors.
    *         Strategy subclasses should pass this reference,
    *         and should not keep a reference themselves.
    *  \param name the strategy Name.
    *         It's recommended to include a version number as the last component.
    *  \todo #3868 name contains version and parameters as instantiated.
    */
   Strategy(Forwarder& forwarder, const Name& name);

   virtual
   ~Strategy();

 #ifdef DOXYGEN
   /** \return a name that represents the strategy program
    *  \todo #3868 This name contains version as given in code,
    *              which may differ from instantiated version.
    */
   static const Name&
   getStrategyName();
 #endif

   /** \return a name that represents the strategy program
    *  \todo #3868 This name contains version and parameters as instantiated.
    */
   const Name&
   getName() const
   {
     return m_name;
   }

 public: // triggers
   /** \brief trigger after Interest is received
    *
    *  The Interest:
    *  - does not violate Scope
    *  - is not looped
    *  - cannot be satisfied by ContentStore
    *  - is under a namespace managed by this strategy
    *
    *  The strategy should decide whether and where to forward this Interest.
    *  - If the strategy decides to forward this Interest,
    *    invoke this->sendInterest one or more times, either now or shortly after
    *  - If strategy concludes that this Interest cannot be forwarded,
    *    invoke this->rejectPendingInterest so that PIT entry will be deleted shortly
    *
    *  \warning The strategy must not retain shared_ptr<pit::Entry>, otherwise undefined behavior
    *           may occur. However, the strategy is allowed to store weak_ptr<pit::Entry>.
    */
   virtual void
   afterReceiveInterest(const Face& inFace, const Interest& interest,
                        const shared_ptr<pit::Entry>& pitEntry) = 0;

   /** \brief trigger before PIT entry is satisfied
    *
    *  This trigger is invoked when an incoming Data satisfies the PIT entry.
    *  It can be invoked even if the PIT entry has already been satisfied.
    *
    *  In this base class this method does nothing.
    *
    *  \warning The strategy must not retain shared_ptr<pit::Entry>, otherwise undefined behavior
    *           may occur. However, the strategy is allowed to store weak_ptr<pit::Entry>.
    */
   virtual void
   beforeSatisfyInterest(const shared_ptr<pit::Entry>& pitEntry,
                         const Face& inFace, const Data& data);

   /** \brief trigger before PIT entry expires
    *
    *  PIT entry expires when InterestLifetime has elapsed for all InRecords,
    *  and it is not satisfied by an incoming Data.
    *
    *  This trigger is not invoked for PIT entry already satisfied.
    *
    *  In this base class this method does nothing.
    *
    *  \warning The strategy must not retain shared_ptr<pit::Entry>, otherwise undefined behavior
    *           may occur. However, the strategy is allowed to store weak_ptr<pit::Entry>,
    *           although this isn't useful here because PIT entry would be deleted shortly after.
    */
   virtual void
   beforeExpirePendingInterest(const shared_ptr<pit::Entry>& pitEntry);

   /** \brief trigger after Nack is received
    *
    *  This trigger is invoked when an incoming Nack is received in response to
    *  an forwarded Interest.
    *  The Nack has been confirmed to be a response to the last Interest forwarded
    *  to that upstream, i.e. the PIT out-record exists and has a matching Nonce.
    *  The NackHeader has been recorded in the PIT out-record.
    *
    *  In this base class this method does nothing.
    *
    *  \warning The strategy must not retain shared_ptr<pit::Entry>, otherwise undefined behavior
    *           may occur. However, the strategy is allowed to store weak_ptr<pit::Entry>.
    */
   virtual void
   afterReceiveNack(const Face& inFace, const lp::Nack& nack,
                    const shared_ptr<pit::Entry>& pitEntry);

 protected: // actions
   /** \brief send Interest to outFace
    *  \param pitEntry PIT entry
    *  \param outFace face through which to send out the Interest
    *  \param interest the Interest packet
    */
   VIRTUAL_WITH_TESTS void
   sendInterest(const shared_ptr<pit::Entry>& pitEntry, Face& outFace,
                const Interest& interest)
   {
     m_forwarder.onOutgoingInterest(pitEntry, outFace, interest);
   }

   /** \brief decide that a pending Interest cannot be forwarded
    *  \param pitEntry PIT entry
    *
    *  This shall not be called if the pending Interest has been
    *  forwarded earlier, and does not need to be resent now.
    */
   VIRTUAL_WITH_TESTS void
   rejectPendingInterest(const shared_ptr<pit::Entry>& pitEntry)
   {
     m_forwarder.onInterestReject(pitEntry);
   }

   /** \brief send Nack to outFace
    *  \param pitEntry PIT entry
    *  \param outFace face through which to send out the Nack
    *  \param header Nack header
    *
    *  The outFace must have a PIT in-record, otherwise this method has no effect.
    */
   VIRTUAL_WITH_TESTS void
   sendNack(const shared_ptr<pit::Entry>& pitEntry, const Face& outFace,
            const lp::NackHeader& header)
   {
     m_forwarder.onOutgoingNack(pitEntry, outFace, header);
   }

   /** \brief send Nack to every face that has an in-record,
    *         except those in \p exceptFaces
    *  \param pitEntry PIT entry
    *  \param header NACK header
    *  \param exceptFaces list of faces that should be excluded from sending Nacks
    *  \note This is not an action, but a helper that invokes the sendNack action.
    */
   void
   sendNacks(const shared_ptr<pit::Entry>& pitEntry, const lp::NackHeader& header,
             std::initializer_list<const Face*> exceptFaces = std::initializer_list<const Face*>());

 protected: // accessors
   /** \brief performs a FIB lookup, considering Link object if present
    */
   const fib::Entry&
   lookupFib(const pit::Entry& pitEntry) const;

   MeasurementsAccessor&
   getMeasurements()
   {
     return m_measurements;
   }

   Face*
   getFace(FaceId id) const
   {
     return m_forwarder.getFace(id);
   }

   const FaceTable&
   getFaceTable() const
   {
     return m_forwarder.getFaceTable();
   }

 protected: // accessors
   signal::Signal<FaceTable, Face&>& afterAddFace;
   signal::Signal<FaceTable, Face&>& beforeRemoveFace;

 private: // registry
   typedef std::function<unique_ptr<Strategy>(Forwarder& forwarder, const Name& strategyName)> CreateFunc;
   typedef std::map<Name, CreateFunc> Registry; // indexed by strategy name

   static Registry&
   getRegistry();

   static Registry::const_iterator
   find(const Name& strategyName);

 private: // instance fields
   Name m_name;

   /** \brief reference to the forwarder
    *
    *  Triggers can access forwarder indirectly via actions.
    */
   Forwarder& m_forwarder;

   MeasurementsAccessor m_measurements;
 };

 } // namespace fw
 } // namespace nfd

 /** \brief registers a strategy
  *
  *  This macro should appear once in .cpp of each strategy.
  */
 #define NFD_REGISTER_STRATEGY(S)                       \
 static class NfdAuto ## S ## StrategyRegistrationClass \
 {                                                      \
 public:                                                \
   NfdAuto ## S ## StrategyRegistrationClass()          \
   {                                                    \
     ::nfd::fw::Strategy::registerType<S>();            \
   }                                                    \
 } g_nfdAuto ## S ## StrategyRegistrationVariable

 #endif // NFD_DAEMON_FW_STRATEGY_HPP
	/* -- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -- */
	/**
	* Copyright (c) 2014-2016, 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/>.
	*/

	#ifndef NFD_DAEMON_FW_STRATEGY_HPP
	#define NFD_DAEMON_FW_STRATEGY_HPP

	#include "forwarder.hpp"
	#include "table/measurements-accessor.hpp"

	namespace nfd {
	namespace fw {

	/** \brief represents a forwarding strategy
	*/
	class Strategy : noncopyable
	{
	public: // registry
	/** \brief register a strategy type
	* \tparam S subclass of Strategy
	* \param strategyName versioned strategy name
	* \note It is permitted to register the same strategy type under multiple names,
	* which is useful in tests and for creating aliases.
	*/
	template<typename S>
	static void
	registerType(const Name& strategyName = S::getStrategyName())
	{
	Registry& registry = getRegistry();
	BOOST_ASSERT(registry.count(strategyName) == 0);
	registry[strategyName] = &make_unique<S, Forwarder&, const Name&>;
	}

	/** \return whether a strategy instance can be created from \p strategyName
	* \param strategyName strategy name, may contain version
	* \todo #3868 may contain parameters
	* \note This function finds a strategy type using same rules as \p create ,
	* but does not attempt to construct an instance.
	*/
	static bool
	canCreate(const Name& strategyName);

	/** \return a strategy instance created from \p strategyName,
	* \retval nullptr if !canCreate(strategyName)
	* \todo #3868 throw std::invalid_argument strategy type constructor
	* does not accept specified version or parameters
	*/
	static unique_ptr<Strategy>
	create(const Name& strategyName, Forwarder& forwarder);

	/** \return registered versioned strategy names
	*/
	static std::set<Name>
	listRegistered();

	public: // constructor, destructor, strategy name
	/** \brief construct a strategy instance
	* \param forwarder a reference to the Forwarder, used to enable actions and accessors.
	* Strategy subclasses should pass this reference,
	* and should not keep a reference themselves.
	* \param name the strategy Name.
	* It's recommended to include a version number as the last component.
	* \todo #3868 name contains version and parameters as instantiated.
	*/
	Strategy(Forwarder& forwarder, const Name& name);

	virtual
	~Strategy();

	#ifdef DOXYGEN
	/** \return a name that represents the strategy program
	* \todo #3868 This name contains version as given in code,
	* which may differ from instantiated version.
	*/
	static const Name&
	getStrategyName();
	#endif

	/** \return a name that represents the strategy program
	* \todo #3868 This name contains version and parameters as instantiated.
	*/
	const Name&
	getName() const
	{
	return m_name;
	}

	public: // triggers
	/** \brief trigger after Interest is received
	*
	* The Interest:
	* - does not violate Scope
	* - is not looped
	* - cannot be satisfied by ContentStore
	* - is under a namespace managed by this strategy
	*
	* The strategy should decide whether and where to forward this Interest.
	* - If the strategy decides to forward this Interest,
	* invoke this->sendInterest one or more times, either now or shortly after
	* - If strategy concludes that this Interest cannot be forwarded,
	* invoke this->rejectPendingInterest so that PIT entry will be deleted shortly
	*
	* \warning The strategy must not retain shared_ptr<pit::Entry>, otherwise undefined behavior
	* may occur. However, the strategy is allowed to store weak_ptr<pit::Entry>.
	*/
	virtual void
	afterReceiveInterest(const Face& inFace, const Interest& interest,
	const shared_ptr<pit::Entry>& pitEntry) = 0;

	/** \brief trigger before PIT entry is satisfied
	*
	* This trigger is invoked when an incoming Data satisfies the PIT entry.
	* It can be invoked even if the PIT entry has already been satisfied.
	*
	* In this base class this method does nothing.
	*
	* \warning The strategy must not retain shared_ptr<pit::Entry>, otherwise undefined behavior
	* may occur. However, the strategy is allowed to store weak_ptr<pit::Entry>.
	*/
	virtual void
	beforeSatisfyInterest(const shared_ptr<pit::Entry>& pitEntry,
	const Face& inFace, const Data& data);

	/** \brief trigger before PIT entry expires
	*
	* PIT entry expires when InterestLifetime has elapsed for all InRecords,
	* and it is not satisfied by an incoming Data.
	*
	* This trigger is not invoked for PIT entry already satisfied.
	*
	* In this base class this method does nothing.
	*
	* \warning The strategy must not retain shared_ptr<pit::Entry>, otherwise undefined behavior
	* may occur. However, the strategy is allowed to store weak_ptr<pit::Entry>,
	* although this isn't useful here because PIT entry would be deleted shortly after.
	*/
	virtual void
	beforeExpirePendingInterest(const shared_ptr<pit::Entry>& pitEntry);

	/** \brief trigger after Nack is received
	*
	* This trigger is invoked when an incoming Nack is received in response to
	* an forwarded Interest.
	* The Nack has been confirmed to be a response to the last Interest forwarded
	* to that upstream, i.e. the PIT out-record exists and has a matching Nonce.
	* The NackHeader has been recorded in the PIT out-record.
	*
	* In this base class this method does nothing.
	*
	* \warning The strategy must not retain shared_ptr<pit::Entry>, otherwise undefined behavior
	* may occur. However, the strategy is allowed to store weak_ptr<pit::Entry>.
	*/
	virtual void
	afterReceiveNack(const Face& inFace, const lp::Nack& nack,
	const shared_ptr<pit::Entry>& pitEntry);

	protected: // actions
	/** \brief send Interest to outFace
	* \param pitEntry PIT entry
	* \param outFace face through which to send out the Interest
	* \param interest the Interest packet
	*/
	VIRTUAL_WITH_TESTS void
	sendInterest(const shared_ptr<pit::Entry>& pitEntry, Face& outFace,
	const Interest& interest)
	{
	m_forwarder.onOutgoingInterest(pitEntry, outFace, interest);
	}

	/** \brief decide that a pending Interest cannot be forwarded
	* \param pitEntry PIT entry
	*
	* This shall not be called if the pending Interest has been
	* forwarded earlier, and does not need to be resent now.
	*/
	VIRTUAL_WITH_TESTS void
	rejectPendingInterest(const shared_ptr<pit::Entry>& pitEntry)
	{
	m_forwarder.onInterestReject(pitEntry);
	}

	/** \brief send Nack to outFace
	* \param pitEntry PIT entry
	* \param outFace face through which to send out the Nack
	* \param header Nack header
	*
	* The outFace must have a PIT in-record, otherwise this method has no effect.
	*/
	VIRTUAL_WITH_TESTS void
	sendNack(const shared_ptr<pit::Entry>& pitEntry, const Face& outFace,
	const lp::NackHeader& header)
	{
	m_forwarder.onOutgoingNack(pitEntry, outFace, header);
	}

	/** \brief send Nack to every face that has an in-record,
	* except those in \p exceptFaces
	* \param pitEntry PIT entry
	* \param header NACK header
	* \param exceptFaces list of faces that should be excluded from sending Nacks
	* \note This is not an action, but a helper that invokes the sendNack action.
	*/
	void
	sendNacks(const shared_ptr<pit::Entry>& pitEntry, const lp::NackHeader& header,
	std::initializer_list<const Face> exceptFaces = std::initializer_list<const Face>());

	protected: // accessors
	/** \brief performs a FIB lookup, considering Link object if present
	*/
	const fib::Entry&
	lookupFib(const pit::Entry& pitEntry) const;

	MeasurementsAccessor&
	getMeasurements()
	{
	return m_measurements;
	}

	Face*
	getFace(FaceId id) const
	{
	return m_forwarder.getFace(id);
	}

	const FaceTable&
	getFaceTable() const
	{
	return m_forwarder.getFaceTable();
	}

	protected: // accessors
	signal::Signal<FaceTable, Face&>& afterAddFace;
	signal::Signal<FaceTable, Face&>& beforeRemoveFace;

	private: // registry
	typedef std::function<unique_ptr<Strategy>(Forwarder& forwarder, const Name& strategyName)> CreateFunc;
	typedef std::map<Name, CreateFunc> Registry; // indexed by strategy name

	static Registry&
	getRegistry();

	static Registry::const_iterator
	find(const Name& strategyName);

	private: // instance fields
	Name m_name;

	/** \brief reference to the forwarder
	*
	* Triggers can access forwarder indirectly via actions.
	*/
	Forwarder& m_forwarder;

	MeasurementsAccessor m_measurements;
	};

	} // namespace fw
	} // namespace nfd

	/** \brief registers a strategy
	*
	* This macro should appear once in .cpp of each strategy.
	*/
	#define NFD_REGISTER_STRATEGY(S) \
	static class NfdAuto ## S ## StrategyRegistrationClass \
	{ \
	public: \
	NfdAuto ## S ## StrategyRegistrationClass() \
	{ \
	::nfd::fw::Strategy::registerType<S>(); \
	} \
	} g_nfdAuto ## S ## StrategyRegistrationVariable

	#endif // NFD_DAEMON_FW_STRATEGY_HPP