Base class of all forwarding strategies. More...

#include <daemon/fw/strategy.hpp>

Inheritance diagram for nfd::fw::Strategy:

Collaboration diagram for nfd::fw::Strategy:

Classes
struct	ParsedInstanceName

Public Member Functions
	Strategy (Forwarder &forwarder)
	Construct a strategy instance. More...

virtual	~Strategy ()

virtual void	afterContentStoreHit (const Data &data, const FaceEndpoint &ingress, const shared_ptr< pit::Entry > &pitEntry)
	Trigger after a matching Data is found in the Content Store. More...

virtual void	afterNewNextHop (const fib::NextHop &nextHop, const shared_ptr< pit::Entry > &pitEntry)
	Trigger after a new nexthop is added. More...

virtual void	afterReceiveData (const Data &data, const FaceEndpoint &ingress, const shared_ptr< pit::Entry > &pitEntry)
	Trigger after Data is received. More...

virtual void	afterReceiveInterest (const Interest &interest, const FaceEndpoint &ingress, const shared_ptr< pit::Entry > &pitEntry)=0
	Trigger after an Interest is received. More...

virtual void	afterReceiveNack (const lp::Nack &nack, const FaceEndpoint &ingress, const shared_ptr< pit::Entry > &pitEntry)
	Trigger after a Nack is received. More...

virtual void	beforeSatisfyInterest (const Data &data, const FaceEndpoint &ingress, const shared_ptr< pit::Entry > &pitEntry)
	Trigger before a PIT entry is satisfied. More...

const Name &	getInstanceName () const noexcept
	Returns the strategy's instance name. More...

virtual void	onDroppedInterest (const Interest &interest, Face &egress)
	Trigger after an Interest is dropped (e.g., for exceeding allowed retransmissions). More...

Static Public Member Functions
static bool	areSameType (const Name &instanceNameA, const Name &instanceNameB)
	Returns whether two names will instantiate the same strategy type. More...

static bool	canCreate (const Name &instanceName)
	Returns whether a strategy instance can be created from `instanceName`. More...

static unique_ptr< Strategy >	create (const Name &instanceName, Forwarder &forwarder)
	Returns a strategy instance created from `instanceName`. More...

static const Name &	getStrategyName ()
	Returns the strategy's program name. More...

static std::set< Name >	listRegistered ()
	Returns all registered versioned strategy names. More...

template<typename S >
static void	registerType (const Name &strategyName=S::getStrategyName())
	Register a strategy type. More...

Protected Member Functions
Face *	getFace (FaceId id) const noexcept

const FaceTable &	getFaceTable () const noexcept

MeasurementsAccessor &	getMeasurements () noexcept

const fib::Entry &	lookupFib (const pit::Entry &pitEntry) const
	Performs a FIB lookup, considering Link object if present. More...

void	rejectPendingInterest (const shared_ptr< pit::Entry > &pitEntry)
	Schedule the PIT entry for immediate deletion. More...

bool	sendData (const Data &data, Face &egress, const shared_ptr< pit::Entry > &pitEntry)
	Send a Data packet. More...

void	sendDataToAll (const Data &data, const shared_ptr< pit::Entry > &pitEntry, const Face &inFace)
	Send a Data packet to all matched and qualified faces. More...

pit::OutRecord *	sendInterest (const Interest &interest, Face &egress, const shared_ptr< pit::Entry > &pitEntry)
	Send an Interest packet. More...

bool	sendNack (const lp::NackHeader &header, Face &egress, const shared_ptr< pit::Entry > &pitEntry)
	Send a Nack packet. More...

void	sendNacks (const lp::NackHeader &header, const shared_ptr< pit::Entry > &pitEntry, std::initializer_list< const Face * > exceptFaces={})
	Send Nack to every face that has an in-record, except those in `exceptFaces`. More...

void	setExpiryTimer (const shared_ptr< pit::Entry > &pitEntry, time::milliseconds duration)
	Schedule the PIT entry to be erased after `duration`. More...

void	setInstanceName (const Name &name) noexcept
	Set strategy instance name. More...

Static Protected Member Functions
static Name	makeInstanceName (const Name &input, const Name &strategyName)
	Construct a strategy instance name. More...

static ParsedInstanceName	parseInstanceName (const Name &input)
	Parse a strategy instance name. More...

static StrategyParameters	parseParameters (const PartialName &params)
	Parse strategy parameters encoded in a strategy instance name. More...

Protected Attributes
signal::Signal< FaceTable, Face > &	afterAddFace

signal::Signal< FaceTable, Face > &	beforeRemoveFace

Detailed Description

Base class of all forwarding strategies.

Definition at line 41 of file strategy.hpp.

Constructor & Destructor Documentation

◆ Strategy()

nfd::fw::Strategy::Strategy ( Forwarder & forwarder )

explicit

Construct a strategy instance.

Parameters

forwarder a reference to the forwarder, used to enable actions and accessors.

Note: Strategy subclass constructor must not retain a reference to forwarder.

Definition at line 166 of file strategy.cpp.

◆ ~Strategy()

nfd::fw::Strategy::~Strategy ( )

virtualdefault

Member Function Documentation

◆ afterContentStoreHit()

void nfd::fw::Strategy::afterContentStoreHit	(	const Data &	data,
		const FaceEndpoint &	ingress,
		const shared_ptr< pit::Entry > &	pitEntry
	)

virtual

Trigger after a matching Data is found in the Content Store.

In the base class, this method sends data to ingress.

Warning: The strategy must not retain a copy of the pitEntry shared_ptr after this function returns, otherwise undefined behavior may occur. However, the strategy is allowed to construct and keep a weak_ptr to pitEntry.

Definition at line 177 of file strategy.cpp.

◆ afterNewNextHop()

void nfd::fw::Strategy::afterNewNextHop	(	const fib::NextHop &	nextHop,
		const shared_ptr< pit::Entry > &	pitEntry
	)

virtual

Trigger after a new nexthop is added.

The strategy should decide whether to send the buffered Interests to the new nexthop.

In the base class, this method does nothing.

Reimplemented in nfd::fw::MulticastStrategy.

Definition at line 219 of file strategy.cpp.

◆ afterReceiveData()

void nfd::fw::Strategy::afterReceiveData	(	const Data &	data,
		const FaceEndpoint &	ingress,
		const shared_ptr< pit::Entry > &	pitEntry
	)

virtual

Trigger after Data is received.

This trigger is invoked when an incoming Data satisfies exactly one PIT entry, and gives the strategy full control over Data forwarding.

When this trigger is invoked:

The Data has been verified to satisfy the PIT entry.
The PIT entry expiry timer is set to now

Inside this function:

A strategy should return Data to downstream nodes via sendData() or sendDataToAll().
A strategy can modify the Data as long as it still satisfies the PIT entry, such as adding or removing congestion marks.
A strategy can delay Data forwarding by prolonging the PIT entry lifetime via setExpiryTimer(), and later forward the Data before the PIT entry is erased.
A strategy can collect measurements about the upstream.
A strategy can collect responses from additional upstream nodes by prolonging the PIT entry lifetime via setExpiryTimer() every time a Data is received. Note that only one Data should be returned to each downstream node.

In the base class, this method invokes beforeSatisfyInterest() and then returns the Data to all downstream faces via sendDataToAll().

Warning: The strategy must not retain a copy of the pitEntry shared_ptr after this function returns, otherwise undefined behavior may occur. However, the strategy is allowed to construct and keep a weak_ptr to pitEntry.

Reimplemented in nfd::fw::SelfLearningStrategy.

Definition at line 195 of file strategy.cpp.

◆ afterReceiveInterest()

virtual void nfd::fw::Strategy::afterReceiveInterest	(	const Interest &	interest,
		const FaceEndpoint &	ingress,
		const shared_ptr< pit::Entry > &	pitEntry
	)

pure virtual

Trigger after an Interest is received.

The Interest:

has not exceeded HopLimit
does not violate Scope
is not looped
cannot be satisfied by ContentStore
is under a namespace managed by this strategy

The PIT entry is set to expire after InterestLifetime has elapsed at each downstream.

The strategy should decide whether and where to forward this Interest.

If the strategy decides to forward this Interest, invoke sendInterest() for each upstream, either now or shortly after via a scheduler event, but before the PIT entry expires. Optionally, the strategy can invoke setExpiryTimer() to adjust how long it would wait for a response.
If the strategy has already forwarded this Interest previously and decides to continue waiting, do nothing. Optionally, the strategy can invoke setExpiryTimer() to adjust how long it would wait for a response.
If the strategy concludes that this Interest cannot be satisfied, invoke rejectPendingInterest() to erase the PIT entry.

Warning: The strategy must not retain a copy of the pitEntry shared_ptr after this function returns, otherwise undefined behavior may occur. However, the strategy is allowed to construct and keep a weak_ptr to pitEntry.

Implemented in nfd::fw::SelfLearningStrategy, nfd::fw::RandomStrategy, nfd::fw::MulticastStrategy, nfd::fw::BestRouteStrategy, nfd::fw::asf::AsfStrategy, and nfd::fw::AccessStrategy.

◆ afterReceiveNack()

void nfd::fw::Strategy::afterReceiveNack	(	const lp::Nack &	nack,
		const FaceEndpoint &	ingress,
		const shared_ptr< pit::Entry > &	pitEntry
	)

virtual

Trigger after a 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.

If the PIT entry is not yet satisfied, its expiry timer remains unchanged. Otherwise, the PIT entry will normally expire immediately after this function returns.

If the strategy wishes to collect responses from additional upstream nodes, it should invoke setExpiryTimer() within this function to prolong the PIT entry lifetime. If a Nack arrives from another upstream during the extended PIT entry lifetime, this trigger will be invoked again. At that time, the strategy must invoke setExpiryTimer() again to continue collecting more responses.

In the base class, this method does nothing.

Warning: The strategy must not retain a copy of the pitEntry shared_ptr after this function returns, otherwise undefined behavior may occur. However, the strategy is allowed to construct and keep a weak_ptr to pitEntry.

Reimplemented in nfd::fw::SelfLearningStrategy, nfd::fw::RandomStrategy, nfd::fw::BestRouteStrategy, and nfd::fw::asf::AsfStrategy.

Definition at line 206 of file strategy.cpp.

◆ areSameType()

bool nfd::fw::Strategy::areSameType	(	const Name &	instanceNameA,
		const Name &	instanceNameB
	)

static

Returns whether two names will instantiate the same strategy type.

Definition at line 108 of file strategy.cpp.

◆ beforeSatisfyInterest()

void nfd::fw::Strategy::beforeSatisfyInterest	(	const Data &	data,
		const FaceEndpoint &	ingress,
		const shared_ptr< pit::Entry > &	pitEntry
	)

virtual

Trigger before a PIT entry is satisfied.

This trigger is invoked when an incoming Data satisfies more than one PIT entry. The strategy can collect measurements information, but cannot manipulate Data forwarding. When an incoming Data satisfies only one PIT entry, afterReceiveData() is invoked instead and given full control over Data forwarding. If a strategy does not override afterReceiveData(), the default implementation invokes beforeSatisfyInterest().

Normally, PIT entries are erased after receiving the first matching Data. If the strategy wishes to collect responses from additional upstream nodes, it should invoke setExpiryTimer() within this function to prolong the PIT entry lifetime. If a Data arrives from another upstream during the extended PIT entry lifetime, this trigger will be invoked again. At that time, the strategy must invoke setExpiryTimer() again to continue collecting more responses.

In the base class, this method does nothing.

Warning: The strategy must not retain a copy of the pitEntry shared_ptr after this function returns, otherwise undefined behavior may occur. However, the strategy is allowed to construct and keep a weak_ptr to pitEntry.

Reimplemented in nfd::fw::asf::AsfStrategy, and nfd::fw::AccessStrategy.

Definition at line 187 of file strategy.cpp.

◆ canCreate()

bool nfd::fw::Strategy::canCreate ( const Name & instanceName )

static

Returns whether a strategy instance can be created from instanceName.

Parameters

instanceName strategy instance name, may contain version and parameters

Note: This function finds a strategy type using the same rules as create(), but does not attempt to construct an instance.

Definition at line 86 of file strategy.cpp.

◆ create()

unique_ptr< Strategy > nfd::fw::Strategy::create	(	const Name &	instanceName,
		Forwarder &	forwarder
	)

static

Returns a strategy instance created from instanceName.

Return values

nullptr if canCreate(instanceName) == false

Exceptions

std::invalid_argument strategy type constructor does not accept the specified version or parameters

Definition at line 92 of file strategy.cpp.

◆ getFace()

Face* nfd::fw::Strategy::getFace ( FaceId id ) const

inlineprotectednoexcept

Definition at line 372 of file strategy.hpp.

◆ getFaceTable()

const FaceTable& nfd::fw::Strategy::getFaceTable ( ) const

inlineprotectednoexcept

Definition at line 378 of file strategy.hpp.

◆ getInstanceName()

const Name& nfd::fw::Strategy::getInstanceName ( ) const

inlinenoexcept

Returns the strategy's instance name.

The instance name is assigned during instantiation. It contains a version component and may have extra parameter components.

Definition at line 122 of file strategy.hpp.

◆ getMeasurements()

MeasurementsAccessor& nfd::fw::Strategy::getMeasurements ( )

inlineprotectednoexcept

Definition at line 366 of file strategy.hpp.

◆ getStrategyName()

static const Name& nfd::fw::Strategy::getStrategyName ( )

static

Returns the strategy's program name.

The strategy name is defined by the strategy program. It must end with a version component.

◆ listRegistered()

std::set< Name > nfd::fw::Strategy::listRegistered ( )

static

Returns all registered versioned strategy names.

Definition at line 114 of file strategy.cpp.

◆ lookupFib()

const fib::Entry & nfd::fw::Strategy::lookupFib ( const pit::Entry & pitEntry ) const

protected

Performs a FIB lookup, considering Link object if present.

Definition at line 304 of file strategy.cpp.

◆ makeInstanceName()

Name nfd::fw::Strategy::makeInstanceName	(	const Name &	input,
		const Name &	strategyName
	)

staticprotected

Construct a strategy instance name.

Parameters

input	strategy instance name, may contain version and parameters
strategyName	strategy name with version but without parameters; typically this should be `getStrategyName()`

If input contains a version component, return input unchanged. Otherwise, return input plus the version component taken from strategyName. This allows a strategy instance to be constructed with an unversioned name, but its final instance name should contain the version.

Definition at line 134 of file strategy.cpp.

◆ onDroppedInterest()

void nfd::fw::Strategy::onDroppedInterest	(	const Interest &	interest,
		Face &	egress
	)

virtual

Trigger after an Interest is dropped (e.g., for exceeding allowed retransmissions).

In the base class, this method does nothing.

Definition at line 213 of file strategy.cpp.

◆ parseInstanceName()

Strategy::ParsedInstanceName nfd::fw::Strategy::parseInstanceName ( const Name & input )

staticprotected

Parse a strategy instance name.

Parameters

input strategy instance name, may contain version and parameters

Exceptions

std::invalid_argument input format is unacceptable

Definition at line 123 of file strategy.cpp.

◆ parseParameters()

StrategyParameters nfd::fw::Strategy::parseParameters ( const PartialName & params )

staticprotected

Parse strategy parameters encoded in a strategy instance name.

Parameters

params encoded parameters, typically obtained from a call to parseInstanceName()

Exceptions

std::invalid_argument the encoding format is invalid or unsupported by this implementation

Definition at line 144 of file strategy.cpp.

◆ registerType()

template<typename S >

static void nfd::fw::Strategy::registerType ( const Name & strategyName = S::getStrategyName() )

inlinestatic

Register a strategy type.

Template Parameters

S	subclass of Strategy

Parameters

strategyName strategy program name, must contain version

Note: It is permitted to register the same strategy type under multiple names, which is useful in tests and for creating aliases.

Definition at line 53 of file strategy.hpp.

◆ rejectPendingInterest()

void nfd::fw::Strategy::rejectPendingInterest ( const shared_ptr< pit::Entry > & pitEntry )

inlineprotected

Schedule the PIT entry for immediate deletion.

This helper function sets the PIT entry expiry time to zero. The strategy should invoke this function when it concludes that the Interest cannot be forwarded and it does not want to wait for responses from existing upstream nodes.

Definition at line 317 of file strategy.hpp.

◆ sendData()

bool nfd::fw::Strategy::sendData	(	const Data &	data,
		Face &	egress,
		const shared_ptr< pit::Entry > &	pitEntry
	)

protected

Send a Data packet.

Parameters

data	the Data packet
egress	face through which to send out the Data
pitEntry	the PIT entry

Returns: Whether the Data was sent (true) or dropped (false)

Definition at line 237 of file strategy.cpp.

◆ sendDataToAll()

void nfd::fw::Strategy::sendDataToAll	(	const Data &	data,
		const shared_ptr< pit::Entry > &	pitEntry,
		const Face &	inFace
	)

protected

Send a Data packet to all matched and qualified faces.

A matched face qualifies if it is ad-hoc OR it is NOT inFace.

Parameters

data	the Data packet
pitEntry	the PIT entry
inFace	face on which the Data arrived

Definition at line 260 of file strategy.cpp.

◆ sendInterest()

pit::OutRecord * nfd::fw::Strategy::sendInterest	(	const Interest &	interest,
		Face &	egress,
		const shared_ptr< pit::Entry > &	pitEntry
	)

protected

Send an Interest packet.

Parameters

interest	the Interest packet
egress	face through which to send out the Interest
pitEntry	the PIT entry

Returns: A pointer to the out-record created or nullptr if the Interest was dropped

Definition at line 226 of file strategy.cpp.

◆ sendNack()

bool nfd::fw::Strategy::sendNack	(	const lp::NackHeader &	header,
		Face &	egress,
		const shared_ptr< pit::Entry > &	pitEntry
	)

inlineprotected

Send a Nack packet.

The egress face must have a PIT in-record, otherwise this method has no effect.

Parameters

header	the Nack header
egress	face through which to send out the Nack
pitEntry	the PIT entry

Returns: Whether the Nack was sent (true) or dropped (false)

Definition at line 333 of file strategy.hpp.

◆ sendNacks()

void nfd::fw::Strategy::sendNacks	(	const lp::NackHeader &	header,
		const shared_ptr< pit::Entry > &	pitEntry,
		std::initializer_list< const Face * >	exceptFaces = `{}`
	)

protected

Send Nack to every face that has an in-record, except those in exceptFaces.

Parameters

header	the Nack header
pitEntry	the PIT entry
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.

Definition at line 282 of file strategy.cpp.

◆ setExpiryTimer()

void nfd::fw::Strategy::setExpiryTimer	(	const shared_ptr< pit::Entry > &	pitEntry,
		time::milliseconds	duration
	)

inlineprotected

Schedule the PIT entry to be erased after duration.

Definition at line 353 of file strategy.hpp.

◆ setInstanceName()

void nfd::fw::Strategy::setInstanceName ( const Name & name )

inlineprotectednoexcept

Set strategy instance name.

Note: This must be called by strategy subclass constructor.

Definition at line 415 of file strategy.hpp.

Member Data Documentation

◆ afterAddFace

signal::Signal<FaceTable, Face>& nfd::fw::Strategy::afterAddFace

protected

Definition at line 440 of file strategy.hpp.

◆ beforeRemoveFace

signal::Signal<FaceTable, Face>& nfd::fw::Strategy::beforeRemoveFace

protected

Definition at line 441 of file strategy.hpp.

NFD: Named Data Networking Forwarding Daemon 22.12 documentation

Classes

Public Member Functions

Static Public Member Functions

Protected Member Functions

Static Protected Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ Strategy()

◆ ~Strategy()

Member Function Documentation

◆ afterContentStoreHit()

◆ afterNewNextHop()

◆ afterReceiveData()

◆ afterReceiveInterest()

◆ afterReceiveNack()

◆ areSameType()

◆ beforeSatisfyInterest()

◆ canCreate()

◆ create()

◆ getFace()

◆ getFaceTable()

◆ getInstanceName()

◆ getMeasurements()

◆ getStrategyName()

◆ listRegistered()

◆ lookupFib()

◆ makeInstanceName()

◆ onDroppedInterest()

◆ parseInstanceName()

◆ parseParameters()

◆ registerType()

◆ rejectPendingInterest()

◆ sendData()

◆ sendDataToAll()

◆ sendInterest()

◆ sendNack()

◆ sendNacks()

◆ setExpiryTimer()

◆ setInstanceName()

Member Data Documentation

◆ afterAddFace

◆ beforeRemoveFace