nfd::fw::AccessStrategy Class Reference

Access Router Strategy version 1. More...

#include <daemon/fw/access-strategy.hpp>

+ Inheritance diagram for nfd::fw::AccessStrategy:
+ Collaboration diagram for nfd::fw::AccessStrategy:

Public Member Functions

 AccessStrategy (Forwarder &forwarder, const Name &name=getStrategyName())
 
virtual void afterContentStoreHit (const shared_ptr< pit::Entry > &pitEntry, const Face &inFace, const Data &data)
 trigger after a Data is matched in CS More...
 
virtual void afterReceiveData (const shared_ptr< pit::Entry > &pitEntry, const Face &inFace, const Data &data)
 trigger after Data is received More...
 
void afterReceiveInterest (const Face &inFace, const Interest &interest, const shared_ptr< pit::Entry > &pitEntry) override
 trigger after Interest is received More...
 
virtual void afterReceiveNack (const Face &inFace, const lp::Nack &nack, const shared_ptr< pit::Entry > &pitEntry)
 trigger after Nack is received More...
 
void beforeSatisfyInterest (const shared_ptr< pit::Entry > &pitEntry, const Face &inFace, const Data &data) override
 trigger before PIT entry is satisfied More...
 
const Name & getInstanceName () const
 
virtual void onDroppedInterest (const Face &outFace, const Interest &interest)
 trigger after Interest dropped for exceeding allowed retransmissions More...
 

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

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 Face &outFace)
 send data to outFace More...
 
void sendDataToAll (const shared_ptr< pit::Entry > &pitEntry, const Face &inFace, const Data &data)
 send data to all matched and qualified faces More...
 
void sendInterest (const shared_ptr< pit::Entry > &pitEntry, Face &outFace, const Interest &interest)
 send Interest to outFace More...
 
void sendNack (const shared_ptr< pit::Entry > &pitEntry, const Face &outFace, const lp::NackHeader &header)
 send Nack to outFace More...
 
void sendNacks (const shared_ptr< pit::Entry > &pitEntry, const lp::NackHeader &header, std::initializer_list< const Face * > exceptFaces=std::initializer_list< const Face * >())
 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)
 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

Access Router Strategy version 1.

This strategy is designed for the last hop on the NDN testbed, where each nexthop connects to a laptop, links are lossy, and FIB is mostly correct.

  1. Multicast the first Interest to all nexthops.
  2. When Data comes back, remember last working nexthop of the prefix; the granularity of this knowledge is the parent of Data Name.
  3. Forward subsequent Interests to the last working nexthop. If it doesn't respond, multicast again.

Definition at line 47 of file access-strategy.hpp.

Constructor & Destructor Documentation

nfd::fw::AccessStrategy::AccessStrategy ( Forwarder forwarder,
const Name &  name = getStrategyName() 
)
explicit

Definition at line 36 of file access-strategy.cpp.

Member Function Documentation

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

trigger after a Data is matched in CS

In the base class this method sends data to inFace

Definition at line 161 of file strategy.cpp.

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

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 171 of file strategy.cpp.

void nfd::fw::AccessStrategy::afterReceiveInterest ( const Face &  inFace,
const Interest &  interest,
const shared_ptr< pit::Entry > &  pitEntry 
)
overridevirtual

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>.

Implements nfd::fw::Strategy.

Definition at line 59 of file access-strategy.cpp.

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

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, and nfd::fw::MulticastStrategy.

Definition at line 183 of file strategy.cpp.

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

Definition at line 107 of file strategy.cpp.

void nfd::fw::AccessStrategy::beforeSatisfyInterest ( const shared_ptr< pit::Entry > &  pitEntry,
const Face &  inFace,
const Data &  data 
)
overridevirtual

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 from nfd::fw::Strategy.

Definition at line 214 of file access-strategy.cpp.

bool nfd::fw::Strategy::canCreate ( const Name &  instanceName)
staticinherited
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 85 of file strategy.cpp.

unique_ptr< Strategy > nfd::fw::Strategy::create ( const Name &  instanceName,
Forwarder forwarder 
)
staticinherited
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 91 of file strategy.cpp.

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

Definition at line 324 of file strategy.hpp.

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

Definition at line 330 of file strategy.hpp.

const Name& nfd::fw::Strategy::getInstanceName ( ) const
inlineinherited
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 110 of file strategy.hpp.

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

Definition at line 318 of file strategy.hpp.

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

Definition at line 52 of file access-strategy.cpp.

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

Definition at line 113 of file strategy.cpp.

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

performs a FIB lookup, considering Link object if present

Definition at line 253 of file strategy.cpp.

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

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 133 of file strategy.cpp.

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

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)
staticprotectedinherited

parse a strategy instance name

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

Definition at line 122 of file strategy.cpp.

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

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)
inlineprotectedinherited

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 273 of file strategy.hpp.

void nfd::fw::Strategy::sendData ( const shared_ptr< pit::Entry > &  pitEntry,
const Data &  data,
const Face &  outFace 
)
protectedinherited

send data to outFace

Parameters
pitEntryPIT entry
datathe Data packet
outFaceface through which to send out the Data

Definition at line 197 of file strategy.cpp.

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

send data to all matched and qualified faces

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

Parameters
pitEntryPIT entry
inFaceface through which the Data comes from
datathe Data packet

Definition at line 209 of file strategy.cpp.

void nfd::fw::Strategy::sendInterest ( const shared_ptr< pit::Entry > &  pitEntry,
Face &  outFace,
const Interest &  interest 
)
inlineprotectedinherited

send Interest to outFace

Parameters
pitEntryPIT entry
outFaceface through which to send out the Interest
interestthe Interest packet

Definition at line 241 of file strategy.hpp.

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

send Nack to outFace

Parameters
pitEntryPIT entry
outFaceface through which to send out the Nack
headerNack header

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

Definition at line 286 of file strategy.hpp.

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

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

Parameters
pitEntryPIT entry
headerNACK header
exceptFaceslist 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 231 of file strategy.cpp.

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

Schedule the PIT entry to be erased after duration.

Definition at line 306 of file strategy.hpp.

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

set strategy instance name

Note
This must be called by strategy subclass constructor.

Definition at line 367 of file strategy.hpp.

Member Data Documentation

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

Definition at line 383 of file strategy.hpp.

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

Definition at line 384 of file strategy.hpp.