nfd::fw::Strategy Class Referenceabstract

represents a forwarding strategy 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 shared_ptr< pit::Entry > &pitEntry, const FaceEndpoint &ingress, const Data &data)
 trigger after a Data is matched in CS More...
 
virtual void afterNewNextHop (const fib::NextHop &nextHop, const shared_ptr< pit::Entry > &pitEntry)
 trigger after new nexthop is added More...
 
virtual void afterReceiveData (const shared_ptr< pit::Entry > &pitEntry, const FaceEndpoint &ingress, const Data &data)
 trigger after Data is received More...
 
virtual void afterReceiveInterest (const FaceEndpoint &ingress, const Interest &interest, const shared_ptr< pit::Entry > &pitEntry)=0
 trigger after Interest is received More...
 
virtual void afterReceiveNack (const FaceEndpoint &ingress, const lp::Nack &nack, const shared_ptr< pit::Entry > &pitEntry)
 trigger after Nack is received More...
 
virtual void beforeSatisfyInterest (const shared_ptr< pit::Entry > &pitEntry, const FaceEndpoint &ingress, const Data &data)
 trigger before PIT entry is satisfied More...
 
const Name & getInstanceName () const
 
virtual void onDroppedInterest (const FaceEndpoint &egress, const Interest &interest)
 trigger after Interest dropped for exceeding allowed retransmissions More...
 
bool wantNewNextHopTrigger () const
 

Static Public Member Functions

static bool areSameType (const Name &instanceNameA, const Name &instanceNameB)
 
static bool canCreate (const Name &instanceName)
 
static unique_ptr< Strategycreate (const Name &instanceName, Forwarder &forwarder)
 
static const Name & getStrategyName ()
 
static std::set< Name > listRegistered ()
 
template<typename S >
static void registerType (const Name &strategyName=S::getStrategyName())
 register a strategy type More...
 

Protected Member Functions

void enableNewNextHopTrigger (bool enabled)
 set whether the afterNewNextHop trigger should be invoked for this strategy More...
 
Face * getFace (FaceId id) const
 
const FaceTablegetFaceTable () const
 
MeasurementsAccessor & getMeasurements ()
 
const fib::EntrylookupFib (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...
 
void sendData (const shared_ptr< pit::Entry > &pitEntry, const Data &data, const FaceEndpoint &egress)
 send data to egress More...
 
void sendDataToAll (const shared_ptr< pit::Entry > &pitEntry, const FaceEndpoint &ingress, const Data &data)
 send data to all matched and qualified face-endpoint pairs More...
 
void sendInterest (const shared_ptr< pit::Entry > &pitEntry, const FaceEndpoint &egress, const Interest &interest)
 send Interest to egress More...
 
void sendNack (const shared_ptr< pit::Entry > &pitEntry, const FaceEndpoint &egress, const lp::NackHeader &header)
 send Nack to egress More...
 
void sendNacks (const shared_ptr< pit::Entry > &pitEntry, const lp::NackHeader &header, std::initializer_list< FaceEndpoint > exceptFaceEndpoints={})
 send Nack to every face-endpoint pair that has an in-record, except those in exceptFaceEndpoints 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)
 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...
 

Protected Attributes

signal::Signal< FaceTable, Face > & afterAddFace
 
signal::Signal< FaceTable, Face > & beforeRemoveFace
 

Detailed Description

represents a forwarding strategy

Definition at line 37 of file strategy.hpp.

Constructor & Destructor Documentation

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

Construct a strategy instance.

Parameters
forwardera reference to the forwarder, used to enable actions and accessors.
Note
Strategy subclass constructor must not retain a reference to forwarder.

Definition at line 143 of file strategy.cpp.

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

Member Function Documentation

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

trigger after a Data is matched in CS

In the base class this method sends data to ingress

Definition at line 162 of file strategy.cpp.

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

trigger after 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.

Definition at line 210 of file strategy.cpp.

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

Within 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 forward 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 trigger and then returns the Data to downstream faces via sendDataToAll.

Reimplemented in nfd::fw::SelfLearningStrategy.

Definition at line 172 of file strategy.cpp.

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

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 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 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 shared_ptr<pit::Entry>, otherwise undefined behavior may occur. However, the strategy is allowed to store weak_ptr<pit::Entry>.

Implemented in nfd::fw::SelfLearningStrategy, nfd::fw::BestRouteStrategy2, nfd::fw::AccessStrategy, nfd::fw::asf::AsfStrategy, nfd::fw::RandomStrategy, nfd::fw::MulticastStrategy, nfd::fw::NccStrategy, and nfd::fw::BestRouteStrategyBase.

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

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.

If the PIT entry is not yet satisfied, its expiry timer remains unchanged. Otherwise, the PIT entry normally would 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 retain the PIT entry. If a Nack arrives from another upstream during the extended PIT entry lifetime, this trigger will be invoked again. At that time, this function must invoke setExpiryTimer again to continue collecting more responses.

In the 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>.

Reimplemented in nfd::fw::SelfLearningStrategy, nfd::fw::BestRouteStrategy2, nfd::fw::asf::AsfStrategy, nfd::fw::RandomStrategy, and nfd::fw::MulticastStrategy.

Definition at line 184 of file strategy.cpp.

bool nfd::fw::Strategy::areSameType ( const Name &  instanceNameA,
const Name &  instanceNameB 
)
static
Returns
whether instanceNameA and instanceNameA will initiate same strategy type

Definition at line 108 of file strategy.cpp.

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

trigger before 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 would be 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, this function must invoke setExpiryTimer again to continue collecting more responses.

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>.

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

Definition at line 154 of file strategy.cpp.

bool nfd::fw::Strategy::canCreate ( const Name &  instanceName)
static
Returns
whether a strategy instance can be created from instanceName
Parameters
instanceNamestrategy instance name, may contain version and parameters
Note
This function finds a strategy type using same rules as create , but does not attempt to construct an instance.

Definition at line 86 of file strategy.cpp.

unique_ptr< Strategy > nfd::fw::Strategy::create ( const Name &  instanceName,
Forwarder forwarder 
)
static
Returns
a strategy instance created from instanceName
Return values
nullptrif !canCreate(instanceName)
Exceptions
std::invalid_argumentstrategy type constructor does not accept specified version or parameters

Definition at line 92 of file strategy.cpp.

void nfd::fw::Strategy::enableNewNextHopTrigger ( bool  enabled)
inlineprotected

set whether the afterNewNextHop trigger should be invoked for this strategy

Definition at line 391 of file strategy.hpp.

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

Definition at line 339 of file strategy.hpp.

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

Definition at line 345 of file strategy.hpp.

const Name& nfd::fw::Strategy::getInstanceName ( ) const
inline
Returns
strategy instance name

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

Definition at line 112 of file strategy.hpp.

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

Definition at line 333 of file strategy.hpp.

static const Name& nfd::fw::Strategy::getStrategyName ( )
static
Returns
strategy program name

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

std::set< Name > nfd::fw::Strategy::listRegistered ( )
static
Returns
registered versioned strategy names

Definition at line 114 of file strategy.cpp.

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 288 of file strategy.cpp.

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

construct a strategy instance name

Parameters
inputstrategy instance name, may contain version and parameters
strategyNamestrategy 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.

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

trigger after Interest dropped for exceeding allowed retransmissions

In the base class this method does nothing.

Definition at line 191 of file strategy.cpp.

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

parse a strategy instance name

Parameters
inputstrategy instance name, may contain version and parameters
Exceptions
std::invalid_argumentinput format is unacceptable

Definition at line 123 of file strategy.cpp.

template<typename S >
static void nfd::fw::Strategy::registerType ( const Name &  strategyName = S::getStrategyName())
inlinestatic

register a strategy type

Template Parameters
Ssubclass of Strategy
Parameters
strategyNamestrategy 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 48 of file strategy.hpp.

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 289 of file strategy.hpp.

void nfd::fw::Strategy::sendData ( const shared_ptr< pit::Entry > &  pitEntry,
const Data &  data,
const FaceEndpoint egress 
)
protected

send data to egress

Parameters
pitEntryPIT entry
datathe Data packet
egressface through which to send out the Data and destination endpoint

Definition at line 217 of file strategy.cpp.

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

send data to all matched and qualified face-endpoint pairs

A matched face is qualified if it is ad-hoc or it is NOT ingress

Parameters
pitEntryPIT entry
ingressface through which the Data comes from and endpoint of the sender
datathe Data packet

Definition at line 242 of file strategy.cpp.

void nfd::fw::Strategy::sendInterest ( const shared_ptr< pit::Entry > &  pitEntry,
const FaceEndpoint egress,
const Interest &  interest 
)
protected

send Interest to egress

Parameters
pitEntryPIT entry
egressface through which to send out the Interest and destination endpoint
interestthe Interest packet

Definition at line 197 of file strategy.cpp.

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

send Nack to egress

Parameters
pitEntryPIT entry
egressface through which to send out the Nack and destination endpoint
headerNack header

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

Definition at line 302 of file strategy.hpp.

void nfd::fw::Strategy::sendNacks ( const shared_ptr< pit::Entry > &  pitEntry,
const lp::NackHeader &  header,
std::initializer_list< FaceEndpoint exceptFaceEndpoints = {} 
)
protected

send Nack to every face-endpoint pair that has an in-record, except those in exceptFaceEndpoints

Parameters
pitEntryPIT entry
headerNACK header
exceptFaceEndpointslist of face-endpoint pairs that should be excluded from sending Nacks
Note
This is not an action, but a helper that invokes the sendNack action.

Definition at line 265 of file strategy.cpp.

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 321 of file strategy.hpp.

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

set strategy instance name

Note
This must be called by strategy subclass constructor.

Definition at line 382 of file strategy.hpp.

bool nfd::fw::Strategy::wantNewNextHopTrigger ( ) const
inline
Returns
whether the afterNewNextHop trigger should be invoked for this strategy.

Definition at line 120 of file strategy.hpp.

Member Data Documentation

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

Definition at line 407 of file strategy.hpp.

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

Definition at line 408 of file strategy.hpp.