daemon/fw/ncc-strategy.cpp - 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/>.
  */

 #include "ncc-strategy.hpp"
 #include "pit-algorithm.hpp"
 #include "core/random.hpp"
 #include <boost/random/uniform_int_distribution.hpp>

 namespace nfd {
 namespace fw {

 const Name NccStrategy::STRATEGY_NAME("ndn:/localhost/nfd/strategy/ncc/%FD%01");
 NFD_REGISTER_STRATEGY(NccStrategy);

 NccStrategy::NccStrategy(Forwarder& forwarder, const Name& name)
   : Strategy(forwarder, name)
 {
 }

 NccStrategy::~NccStrategy()
 {
 }

 const time::microseconds NccStrategy::DEFER_FIRST_WITHOUT_BEST_FACE = time::microseconds(4000);
 const time::microseconds NccStrategy::DEFER_RANGE_WITHOUT_BEST_FACE = time::microseconds(75000);
 const time::nanoseconds NccStrategy::MEASUREMENTS_LIFETIME = time::seconds(16);

 void
 NccStrategy::afterReceiveInterest(const Face& inFace,
                                   const Interest& interest,
                                   shared_ptr<fib::Entry> fibEntry,
                                   shared_ptr<pit::Entry> pitEntry)
 {
   const fib::NextHopList& nexthops = fibEntry->getNextHops();
   if (nexthops.size() == 0) {
     this->rejectPendingInterest(pitEntry);
     return;
   }

   shared_ptr<PitEntryInfo> pitEntryInfo =
     pitEntry->getOrCreateStrategyInfo<PitEntryInfo>();
   bool isNewPitEntry = !hasPendingOutRecords(*pitEntry);
   if (!isNewPitEntry) {
     return;
   }

   shared_ptr<MeasurementsEntryInfo> measurementsEntryInfo =
     this->getMeasurementsEntryInfo(pitEntry);

   time::microseconds deferFirst = DEFER_FIRST_WITHOUT_BEST_FACE;
   time::microseconds deferRange = DEFER_RANGE_WITHOUT_BEST_FACE;
   size_t nUpstreams = nexthops.size();

   shared_ptr<Face> bestFace = measurementsEntryInfo->getBestFace();
   if (static_cast<bool>(bestFace) && fibEntry->hasNextHop(bestFace) &&
       canForwardToLegacy(*pitEntry, *bestFace)) {
     // TODO Should we use `randlow = 100 + nrand48(h->seed) % 4096U;` ?
     deferFirst = measurementsEntryInfo->prediction;
     deferRange = time::microseconds((deferFirst.count() + 1) / 2);
     --nUpstreams;
     this->sendInterest(pitEntry, bestFace);
     pitEntryInfo->bestFaceTimeout = scheduler::schedule(
       measurementsEntryInfo->prediction,
       bind(&NccStrategy::timeoutOnBestFace, this, weak_ptr<pit::Entry>(pitEntry)));
   }
   else {
     // use first eligible nexthop
     auto firstEligibleNexthop = std::find_if(nexthops.begin(), nexthops.end(),
         [&pitEntry] (const fib::NextHop& nexthop) {
           return canForwardToLegacy(*pitEntry, *nexthop.getFace());
         });
     if (firstEligibleNexthop != nexthops.end()) {
       this->sendInterest(pitEntry, firstEligibleNexthop->getFace());
     }
   }

   shared_ptr<Face> previousFace = measurementsEntryInfo->previousFace.lock();
   if (static_cast<bool>(previousFace) && fibEntry->hasNextHop(previousFace) &&
       canForwardToLegacy(*pitEntry, *previousFace)) {
     --nUpstreams;
   }

   if (nUpstreams > 0) {
     pitEntryInfo->maxInterval = std::max(time::microseconds(1),
       time::microseconds((2 * deferRange.count() + nUpstreams - 1) / nUpstreams));
   }
   else {
     // Normally, maxInterval is unused if there aren't any face beyond best and previousBest.
     // However, in case FIB entry gains a new nexthop before doPropagate executes (bug 1853),
     // this maxInterval would be used to determine when the next doPropagate would happen.
     pitEntryInfo->maxInterval = deferFirst;
   }
   pitEntryInfo->propagateTimer = scheduler::schedule(deferFirst,
     bind(&NccStrategy::doPropagate, this,
          weak_ptr<pit::Entry>(pitEntry), weak_ptr<fib::Entry>(fibEntry)));
 }

 void
 NccStrategy::doPropagate(weak_ptr<pit::Entry> pitEntryWeak, weak_ptr<fib::Entry> fibEntryWeak)
 {
   shared_ptr<pit::Entry> pitEntry = pitEntryWeak.lock();
   if (!static_cast<bool>(pitEntry)) {
     return;
   }
   shared_ptr<fib::Entry> fibEntry = fibEntryWeak.lock();
   if (!static_cast<bool>(fibEntry)) {
     return;
   }

   shared_ptr<PitEntryInfo> pitEntryInfo = pitEntry->getStrategyInfo<PitEntryInfo>();
   // pitEntryInfo is guaranteed to exist here, because doPropagate is triggered
   // from a timer set by NccStrategy.
   BOOST_ASSERT(static_cast<bool>(pitEntryInfo));

   shared_ptr<MeasurementsEntryInfo> measurementsEntryInfo =
     this->getMeasurementsEntryInfo(pitEntry);

   shared_ptr<Face> previousFace = measurementsEntryInfo->previousFace.lock();
   if (static_cast<bool>(previousFace) && fibEntry->hasNextHop(previousFace) &&
       canForwardToLegacy(*pitEntry, *previousFace)) {
     this->sendInterest(pitEntry, previousFace);
   }

   const fib::NextHopList& nexthops = fibEntry->getNextHops();
   bool isForwarded = false;
   for (fib::NextHopList::const_iterator it = nexthops.begin(); it != nexthops.end(); ++it) {
     shared_ptr<Face> face = it->getFace();
     if (canForwardToLegacy(*pitEntry, *face)) {
       isForwarded = true;
       this->sendInterest(pitEntry, face);
       break;
     }
   }

   if (isForwarded) {
     boost::random::uniform_int_distribution<time::nanoseconds::rep> dist(0,
       pitEntryInfo->maxInterval.count() - 1);
     time::nanoseconds deferNext = time::nanoseconds(dist(getGlobalRng()));
     pitEntryInfo->propagateTimer = scheduler::schedule(deferNext,
     bind(&NccStrategy::doPropagate, this,
          weak_ptr<pit::Entry>(pitEntry), weak_ptr<fib::Entry>(fibEntry)));
   }
 }

 void
 NccStrategy::timeoutOnBestFace(weak_ptr<pit::Entry> pitEntryWeak)
 {
   shared_ptr<pit::Entry> pitEntry = pitEntryWeak.lock();
   if (!static_cast<bool>(pitEntry)) {
     return;
   }
   shared_ptr<measurements::Entry> measurementsEntry = this->getMeasurements().get(*pitEntry);

   for (int i = 0; i < UPDATE_MEASUREMENTS_N_LEVELS; ++i) {
     if (!static_cast<bool>(measurementsEntry)) {
       // going out of this strategy's namespace
       return;
     }
     this->getMeasurements().extendLifetime(*measurementsEntry, MEASUREMENTS_LIFETIME);

     shared_ptr<MeasurementsEntryInfo> measurementsEntryInfo =
       this->getMeasurementsEntryInfo(measurementsEntry);
     measurementsEntryInfo->adjustPredictUp();

     measurementsEntry = this->getMeasurements().getParent(*measurementsEntry);
   }
 }

 void
 NccStrategy::beforeSatisfyInterest(shared_ptr<pit::Entry> pitEntry,
                                    const Face& inFace, const Data& data)
 {
   if (!pitEntry->hasInRecords()) {
     // PIT entry has already been satisfied (and is now waiting for straggler timer to expire)
     // NCC does not collect measurements for non-best face
     return;
   }

   shared_ptr<measurements::Entry> measurementsEntry = this->getMeasurements().get(*pitEntry);

   for (int i = 0; i < UPDATE_MEASUREMENTS_N_LEVELS; ++i) {
     if (!static_cast<bool>(measurementsEntry)) {
       // going out of this strategy's namespace
       return;
     }
     this->getMeasurements().extendLifetime(*measurementsEntry, MEASUREMENTS_LIFETIME);

     shared_ptr<MeasurementsEntryInfo> measurementsEntryInfo =
       this->getMeasurementsEntryInfo(measurementsEntry);
     measurementsEntryInfo->updateBestFace(inFace);

     measurementsEntry = this->getMeasurements().getParent(*measurementsEntry);
   }

   shared_ptr<PitEntryInfo> pitEntryInfo = pitEntry->getStrategyInfo<PitEntryInfo>();
   if (pitEntryInfo != nullptr) {
     scheduler::cancel(pitEntryInfo->propagateTimer);

     // Verify that the best face satisfied the interest before canceling the timeout call
     shared_ptr<MeasurementsEntryInfo> measurementsEntryInfo =
       this->getMeasurementsEntryInfo(pitEntry);
     shared_ptr<Face> bestFace = measurementsEntryInfo->getBestFace();

     if (bestFace.get() == &inFace)
       scheduler::cancel(pitEntryInfo->bestFaceTimeout);
   }
 }

 shared_ptr<NccStrategy::MeasurementsEntryInfo>
 NccStrategy::getMeasurementsEntryInfo(shared_ptr<pit::Entry> entry)
 {
   shared_ptr<measurements::Entry> measurementsEntry = this->getMeasurements().get(*entry);
   return this->getMeasurementsEntryInfo(measurementsEntry);
 }

 shared_ptr<NccStrategy::MeasurementsEntryInfo>
 NccStrategy::getMeasurementsEntryInfo(shared_ptr<measurements::Entry> entry)
 {
   shared_ptr<MeasurementsEntryInfo> info = entry->getStrategyInfo<MeasurementsEntryInfo>();
   if (static_cast<bool>(info)) {
     return info;
   }

   info = make_shared<MeasurementsEntryInfo>();
   entry->setStrategyInfo(info);

   shared_ptr<measurements::Entry> parentEntry = this->getMeasurements().getParent(*entry);
   if (static_cast<bool>(parentEntry)) {
     shared_ptr<MeasurementsEntryInfo> parentInfo = this->getMeasurementsEntryInfo(parentEntry);
     BOOST_ASSERT(static_cast<bool>(parentInfo));
     info->inheritFrom(*parentInfo);
   }

   return info;
 }


 const time::microseconds NccStrategy::MeasurementsEntryInfo::INITIAL_PREDICTION =
                                                              time::microseconds(8192);
 const time::microseconds NccStrategy::MeasurementsEntryInfo::MIN_PREDICTION =
                                                              time::microseconds(127);
 const time::microseconds NccStrategy::MeasurementsEntryInfo::MAX_PREDICTION =
                                                              time::microseconds(160000);

 NccStrategy::MeasurementsEntryInfo::MeasurementsEntryInfo()
   : prediction(INITIAL_PREDICTION)
 {
 }

 void
 NccStrategy::MeasurementsEntryInfo::inheritFrom(const MeasurementsEntryInfo& other)
 {
   this->operator=(other);
 }

 shared_ptr<Face>
 NccStrategy::MeasurementsEntryInfo::getBestFace(void) {
   shared_ptr<Face> best = this->bestFace.lock();
   if (static_cast<bool>(best)) {
     return best;
   }
   this->bestFace = best = this->previousFace.lock();
   return best;
 }

 void
 NccStrategy::MeasurementsEntryInfo::updateBestFace(const Face& face) {
   if (this->bestFace.expired()) {
     this->bestFace = const_cast<Face&>(face).shared_from_this();
     return;
   }
   shared_ptr<Face> bestFace = this->bestFace.lock();
   if (bestFace.get() == &face) {
     this->adjustPredictDown();
   }
   else {
     this->previousFace = this->bestFace;
     this->bestFace = const_cast<Face&>(face).shared_from_this();
   }
 }

 void
 NccStrategy::MeasurementsEntryInfo::adjustPredictDown() {
   prediction = std::max(MIN_PREDICTION,
     time::microseconds(prediction.count() - (prediction.count() >> ADJUST_PREDICT_DOWN_SHIFT)));
 }

 void
 NccStrategy::MeasurementsEntryInfo::adjustPredictUp() {
   prediction = std::min(MAX_PREDICTION,
     time::microseconds(prediction.count() + (prediction.count() >> ADJUST_PREDICT_UP_SHIFT)));
 }

 void
 NccStrategy::MeasurementsEntryInfo::ageBestFace() {
   this->previousFace = this->bestFace;
   this->bestFace.reset();
 }

 NccStrategy::PitEntryInfo::~PitEntryInfo()
 {
   scheduler::cancel(this->bestFaceTimeout);
   scheduler::cancel(this->propagateTimer);
 }

 } // namespace fw
 } // namespace nfd
	/* -- 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/>.
	*/

	#include "ncc-strategy.hpp"
	#include "pit-algorithm.hpp"
	#include "core/random.hpp"
	#include <boost/random/uniform_int_distribution.hpp>

	namespace nfd {
	namespace fw {

	const Name NccStrategy::STRATEGY_NAME("ndn:/localhost/nfd/strategy/ncc/%FD%01");
	NFD_REGISTER_STRATEGY(NccStrategy);

	NccStrategy::NccStrategy(Forwarder& forwarder, const Name& name)
	: Strategy(forwarder, name)
	{
	}

	NccStrategy::~NccStrategy()
	{
	}

	const time::microseconds NccStrategy::DEFER_FIRST_WITHOUT_BEST_FACE = time::microseconds(4000);
	const time::microseconds NccStrategy::DEFER_RANGE_WITHOUT_BEST_FACE = time::microseconds(75000);
	const time::nanoseconds NccStrategy::MEASUREMENTS_LIFETIME = time::seconds(16);

	void
	NccStrategy::afterReceiveInterest(const Face& inFace,
	const Interest& interest,
	shared_ptr<fib::Entry> fibEntry,
	shared_ptr<pit::Entry> pitEntry)
	{
	const fib::NextHopList& nexthops = fibEntry->getNextHops();
	if (nexthops.size() == 0) {
	this->rejectPendingInterest(pitEntry);
	return;
	}

	shared_ptr<PitEntryInfo> pitEntryInfo =
	pitEntry->getOrCreateStrategyInfo<PitEntryInfo>();
	bool isNewPitEntry = !hasPendingOutRecords(*pitEntry);
	if (!isNewPitEntry) {
	return;
	}

	shared_ptr<MeasurementsEntryInfo> measurementsEntryInfo =
	this->getMeasurementsEntryInfo(pitEntry);

	time::microseconds deferFirst = DEFER_FIRST_WITHOUT_BEST_FACE;
	time::microseconds deferRange = DEFER_RANGE_WITHOUT_BEST_FACE;
	size_t nUpstreams = nexthops.size();

	shared_ptr<Face> bestFace = measurementsEntryInfo->getBestFace();
	if (static_cast<bool>(bestFace) && fibEntry->hasNextHop(bestFace) &&
	canForwardToLegacy(pitEntry, bestFace)) {
	// TODO Should we use `randlow = 100 + nrand48(h->seed) % 4096U;` ?
	deferFirst = measurementsEntryInfo->prediction;
	deferRange = time::microseconds((deferFirst.count() + 1) / 2);
	--nUpstreams;
	this->sendInterest(pitEntry, bestFace);
	pitEntryInfo->bestFaceTimeout = scheduler::schedule(
	measurementsEntryInfo->prediction,
	bind(&NccStrategy::timeoutOnBestFace, this, weak_ptr<pit::Entry>(pitEntry)));
	}
	else {
	// use first eligible nexthop
	auto firstEligibleNexthop = std::find_if(nexthops.begin(), nexthops.end(),
	[&pitEntry] (const fib::NextHop& nexthop) {
	return canForwardToLegacy(pitEntry, nexthop.getFace());
	});
	if (firstEligibleNexthop != nexthops.end()) {
	this->sendInterest(pitEntry, firstEligibleNexthop->getFace());
	}
	}

	shared_ptr<Face> previousFace = measurementsEntryInfo->previousFace.lock();
	if (static_cast<bool>(previousFace) && fibEntry->hasNextHop(previousFace) &&
	canForwardToLegacy(pitEntry, previousFace)) {
	--nUpstreams;
	}

	if (nUpstreams > 0) {
	pitEntryInfo->maxInterval = std::max(time::microseconds(1),
	time::microseconds((2 * deferRange.count() + nUpstreams - 1) / nUpstreams));
	}
	else {
	// Normally, maxInterval is unused if there aren't any face beyond best and previousBest.
	// However, in case FIB entry gains a new nexthop before doPropagate executes (bug 1853),
	// this maxInterval would be used to determine when the next doPropagate would happen.
	pitEntryInfo->maxInterval = deferFirst;
	}
	pitEntryInfo->propagateTimer = scheduler::schedule(deferFirst,
	bind(&NccStrategy::doPropagate, this,
	weak_ptr<pit::Entry>(pitEntry), weak_ptr<fib::Entry>(fibEntry)));
	}

	void
	NccStrategy::doPropagate(weak_ptr<pit::Entry> pitEntryWeak, weak_ptr<fib::Entry> fibEntryWeak)
	{
	shared_ptr<pit::Entry> pitEntry = pitEntryWeak.lock();
	if (!static_cast<bool>(pitEntry)) {
	return;
	}
	shared_ptr<fib::Entry> fibEntry = fibEntryWeak.lock();
	if (!static_cast<bool>(fibEntry)) {
	return;
	}

	shared_ptr<PitEntryInfo> pitEntryInfo = pitEntry->getStrategyInfo<PitEntryInfo>();
	// pitEntryInfo is guaranteed to exist here, because doPropagate is triggered
	// from a timer set by NccStrategy.
	BOOST_ASSERT(static_cast<bool>(pitEntryInfo));

	shared_ptr<MeasurementsEntryInfo> measurementsEntryInfo =
	this->getMeasurementsEntryInfo(pitEntry);

	shared_ptr<Face> previousFace = measurementsEntryInfo->previousFace.lock();
	if (static_cast<bool>(previousFace) && fibEntry->hasNextHop(previousFace) &&
	canForwardToLegacy(pitEntry, previousFace)) {
	this->sendInterest(pitEntry, previousFace);
	}

	const fib::NextHopList& nexthops = fibEntry->getNextHops();
	bool isForwarded = false;
	for (fib::NextHopList::const_iterator it = nexthops.begin(); it != nexthops.end(); ++it) {
	shared_ptr<Face> face = it->getFace();
	if (canForwardToLegacy(pitEntry, face)) {
	isForwarded = true;
	this->sendInterest(pitEntry, face);
	break;
	}
	}

	if (isForwarded) {
	boost::random::uniform_int_distribution<time::nanoseconds::rep> dist(0,
	pitEntryInfo->maxInterval.count() - 1);
	time::nanoseconds deferNext = time::nanoseconds(dist(getGlobalRng()));
	pitEntryInfo->propagateTimer = scheduler::schedule(deferNext,
	bind(&NccStrategy::doPropagate, this,
	weak_ptr<pit::Entry>(pitEntry), weak_ptr<fib::Entry>(fibEntry)));
	}
	}

	void
	NccStrategy::timeoutOnBestFace(weak_ptr<pit::Entry> pitEntryWeak)
	{
	shared_ptr<pit::Entry> pitEntry = pitEntryWeak.lock();
	if (!static_cast<bool>(pitEntry)) {
	return;
	}
	shared_ptr<measurements::Entry> measurementsEntry = this->getMeasurements().get(*pitEntry);

	for (int i = 0; i < UPDATE_MEASUREMENTS_N_LEVELS; ++i) {
	if (!static_cast<bool>(measurementsEntry)) {
	// going out of this strategy's namespace
	return;
	}
	this->getMeasurements().extendLifetime(*measurementsEntry, MEASUREMENTS_LIFETIME);

	shared_ptr<MeasurementsEntryInfo> measurementsEntryInfo =
	this->getMeasurementsEntryInfo(measurementsEntry);
	measurementsEntryInfo->adjustPredictUp();

	measurementsEntry = this->getMeasurements().getParent(*measurementsEntry);
	}
	}

	void
	NccStrategy::beforeSatisfyInterest(shared_ptr<pit::Entry> pitEntry,
	const Face& inFace, const Data& data)
	{
	if (!pitEntry->hasInRecords()) {
	// PIT entry has already been satisfied (and is now waiting for straggler timer to expire)
	// NCC does not collect measurements for non-best face
	return;
	}

	shared_ptr<measurements::Entry> measurementsEntry = this->getMeasurements().get(*pitEntry);

	for (int i = 0; i < UPDATE_MEASUREMENTS_N_LEVELS; ++i) {
	if (!static_cast<bool>(measurementsEntry)) {
	// going out of this strategy's namespace
	return;
	}
	this->getMeasurements().extendLifetime(*measurementsEntry, MEASUREMENTS_LIFETIME);

	shared_ptr<MeasurementsEntryInfo> measurementsEntryInfo =
	this->getMeasurementsEntryInfo(measurementsEntry);
	measurementsEntryInfo->updateBestFace(inFace);

	measurementsEntry = this->getMeasurements().getParent(*measurementsEntry);
	}

	shared_ptr<PitEntryInfo> pitEntryInfo = pitEntry->getStrategyInfo<PitEntryInfo>();
	if (pitEntryInfo != nullptr) {
	scheduler::cancel(pitEntryInfo->propagateTimer);

	// Verify that the best face satisfied the interest before canceling the timeout call
	shared_ptr<MeasurementsEntryInfo> measurementsEntryInfo =
	this->getMeasurementsEntryInfo(pitEntry);
	shared_ptr<Face> bestFace = measurementsEntryInfo->getBestFace();

	if (bestFace.get() == &inFace)
	scheduler::cancel(pitEntryInfo->bestFaceTimeout);
	}
	}

	shared_ptr<NccStrategy::MeasurementsEntryInfo>
	NccStrategy::getMeasurementsEntryInfo(shared_ptr<pit::Entry> entry)
	{
	shared_ptr<measurements::Entry> measurementsEntry = this->getMeasurements().get(*entry);
	return this->getMeasurementsEntryInfo(measurementsEntry);
	}

	shared_ptr<NccStrategy::MeasurementsEntryInfo>
	NccStrategy::getMeasurementsEntryInfo(shared_ptr<measurements::Entry> entry)
	{
	shared_ptr<MeasurementsEntryInfo> info = entry->getStrategyInfo<MeasurementsEntryInfo>();
	if (static_cast<bool>(info)) {
	return info;
	}

	info = make_shared<MeasurementsEntryInfo>();
	entry->setStrategyInfo(info);

	shared_ptr<measurements::Entry> parentEntry = this->getMeasurements().getParent(*entry);
	if (static_cast<bool>(parentEntry)) {
	shared_ptr<MeasurementsEntryInfo> parentInfo = this->getMeasurementsEntryInfo(parentEntry);
	BOOST_ASSERT(static_cast<bool>(parentInfo));
	info->inheritFrom(*parentInfo);
	}

	return info;
	}


	const time::microseconds NccStrategy::MeasurementsEntryInfo::INITIAL_PREDICTION =
	time::microseconds(8192);
	const time::microseconds NccStrategy::MeasurementsEntryInfo::MIN_PREDICTION =
	time::microseconds(127);
	const time::microseconds NccStrategy::MeasurementsEntryInfo::MAX_PREDICTION =
	time::microseconds(160000);

	NccStrategy::MeasurementsEntryInfo::MeasurementsEntryInfo()
	: prediction(INITIAL_PREDICTION)
	{
	}

	void
	NccStrategy::MeasurementsEntryInfo::inheritFrom(const MeasurementsEntryInfo& other)
	{
	this->operator=(other);
	}

	shared_ptr<Face>
	NccStrategy::MeasurementsEntryInfo::getBestFace(void) {
	shared_ptr<Face> best = this->bestFace.lock();
	if (static_cast<bool>(best)) {
	return best;
	}
	this->bestFace = best = this->previousFace.lock();
	return best;
	}

	void
	NccStrategy::MeasurementsEntryInfo::updateBestFace(const Face& face) {
	if (this->bestFace.expired()) {
	this->bestFace = const_cast<Face&>(face).shared_from_this();
	return;
	}
	shared_ptr<Face> bestFace = this->bestFace.lock();
	if (bestFace.get() == &face) {
	this->adjustPredictDown();
	}
	else {
	this->previousFace = this->bestFace;
	this->bestFace = const_cast<Face&>(face).shared_from_this();
	}
	}

	void
	NccStrategy::MeasurementsEntryInfo::adjustPredictDown() {
	prediction = std::max(MIN_PREDICTION,
	time::microseconds(prediction.count() - (prediction.count() >> ADJUST_PREDICT_DOWN_SHIFT)));
	}

	void
	NccStrategy::MeasurementsEntryInfo::adjustPredictUp() {
	prediction = std::min(MAX_PREDICTION,
	time::microseconds(prediction.count() + (prediction.count() >> ADJUST_PREDICT_UP_SHIFT)));
	}

	void
	NccStrategy::MeasurementsEntryInfo::ageBestFace() {
	this->previousFace = this->bestFace;
	this->bestFace.reset();
	}

	NccStrategy::PitEntryInfo::~PitEntryInfo()
	{
	scheduler::cancel(this->bestFaceTimeout);
	scheduler::cancel(this->propagateTimer);
	}

	} // namespace fw
	} // namespace nfd