Template class implementing a Lollipop counter as defined in RFC 8505 , RFC 6550 , and [Perlman83]. More...

#include "lollipop-counter.h"

Collaboration diagram for ns3::LollipopCounter< T >:

Public Member Functions
	LollipopCounter ()
	Builds a Lollipop counter with a default initial value.

	LollipopCounter (T val)
	Builds a Lollipop counter with a specific initial value.

T	GetValue () const
	Get the counter value.

bool	IsComparable (const LollipopCounter &val) const
	Checks if the counter is comparable with another counter (i.e., not desynchronized).

bool	IsInit () const
	Checks if a counter is in its starting region.

LollipopCounter &	operator= (const LollipopCounter &o)
	Assignment.

void	Reset ()
	Resets the counter to its initial value.

void	SetSequenceWindowSize (uint16_t numberOfBits)
	Set the Sequence Window Size and resets the counter.

Private Member Functions
T	AbsoluteMagnitudeOfDifference (const LollipopCounter &val) const
	Compute the Absolute Magnitude Of Difference between two counters.

Private Attributes
T	m_sequenceWindow
	Sequence window used for comparing two counters.

T	m_value
	Value of the Lollipop Counter.

Static Private Attributes
static constexpr T	m_circularRegion = m_maxValue >> 1
	Circular region of the counter.

static constexpr T	m_maxValue
	Maximum value of the counter.

Friends
LollipopCounter	operator++ (LollipopCounter &val)
	Prefix increment operator.

LollipopCounter	operator++ (LollipopCounter &val, int noop)
	Postfix increment operator.

bool	operator< (const LollipopCounter &lhs, const LollipopCounter &rhs)
	Arithmetic operator less-than.

std::ostream &	operator<< (std::ostream &os, const LollipopCounter &counter)
	Output streamer for LollipopCounter.

bool	operator== (const LollipopCounter &lhs, const LollipopCounter &rhs)
	Arithmetic operator equal-to.

bool	operator> (const LollipopCounter &lhs, const LollipopCounter &rhs)
	Arithmetic operator greater-than.

Detailed Description

template<class T>
class ns3::LollipopCounter< T >

Template class implementing a Lollipop counter as defined in RFC 8505 , RFC 6550 , and [Perlman83].

A Lollipop counter is a counter that solves initialization and out-of-order problems often occurring in Internet protocols.

The counter is split in two regions, an initializing region, and a circular region, having the same size. Assuming a counter using an uint8_t (max value 255), values from 128 and greater are used as a linear sequence to indicate a restart and bootstrap the counter, and the values less than or equal to 127 are used as a circular sequence number space of size 128 as mentioned in RFC 1982 .

In both regions, the comparison between two counters is allowed only if both counters are inside a Sequence Window. The default value for the Sequence Window is equal to 2^N where N is half the number of digits of the underlying type. For an uint8_t the Sequence Window is 16.

The counter, by default, is initialized to the maximum counter value minus the Sequence Window plus one, e.g., in case of a uint8_t, to 240.

This implementation extends the case presented in RFCs, allowing to use a larger underlying type and to change the Sequence Window size.

Warning: two Lollipop counters can be compared only if they are of the same type (same underlying type, and same Sequence Window).

References: [Perlman83] Perlman, R., "Fault-Tolerant Broadcast of Routing Information", North-Holland Computer Networks 7: pp. 395-405, DOI 10.1016/0376-5075(83)90034-X, 1983, https://web.archive.org/web/20180723135334/http://pbg.cs.illinois.edu/courses/cs598fa09/readings/p83.pdf.

Template Parameters

T	[explicit] The type being used for the counter.

Definition at line 56 of file lollipop-counter.h.

Constructor & Destructor Documentation

◆ LollipopCounter() [1/2]

template<class T >

ns3::LollipopCounter< T >::LollipopCounter ( )

inline

Builds a Lollipop counter with a default initial value.

The Sequence Window is set to the default value. The initial value is set to the maximum counter value minus the Sequence Window plus one.

Definition at line 65 of file lollipop-counter.h.

References ns3::LollipopCounter< T >::m_maxValue, ns3::LollipopCounter< T >::m_sequenceWindow, ns3::LollipopCounter< T >::m_value, and NS_ABORT_MSG_UNLESS.

◆ LollipopCounter() [2/2]

template<class T >

ns3::LollipopCounter< T >::LollipopCounter ( T val )

inline

Builds a Lollipop counter with a specific initial value.

The Sequence Window is set to the default value.

Parameters

val	the initial value of the Lollipop Counter

Template Parameters

T	[deduced] The type being used for the counter.

Definition at line 84 of file lollipop-counter.h.

References ns3::LollipopCounter< T >::m_sequenceWindow, and ns3::LollipopCounter< T >::m_value.

Member Function Documentation

◆ AbsoluteMagnitudeOfDifference()

template<class T >

T ns3::LollipopCounter< T >::AbsoluteMagnitudeOfDifference ( const LollipopCounter< T > & val ) const

inlineprivate

Compute the Absolute Magnitude Of Difference between two counters.

The Absolute Magnitude Of Difference is considered to be on a circular region, and it is represented by the smallest circular distance between two numbers.

Arithmetic operator.

Parameters

[in] val Counter to compute the difference against

Returns: The result of the difference.

Definition at line 344 of file lollipop-counter.h.

References ns3::LollipopCounter< T >::m_circularRegion, and ns3::LollipopCounter< T >::m_value.

Referenced by ns3::LollipopCounter< T >::IsComparable().

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◆ GetValue()

template<class T >

T ns3::LollipopCounter< T >::GetValue ( ) const

inline

Get the counter value.

Returns: the counter value.

Definition at line 314 of file lollipop-counter.h.

References ns3::LollipopCounter< T >::m_value.

◆ IsComparable()

template<class T >

bool ns3::LollipopCounter< T >::IsComparable ( const LollipopCounter< T > & val ) const

inline

Checks if the counter is comparable with another counter (i.e., not desynchronized).

If the absolute magnitude of difference of the two sequence counters is greater than Sequence Window, then a desynchronization has occurred and the two sequence numbers are not comparable.

Sequence Window is equal to 2^N where N is (by default) half the number of digits of the underlying type.

Parameters

val	counter to compare

Returns: true if the counters are comparable.

Definition at line 149 of file lollipop-counter.h.

References ns3::LollipopCounter< T >::AbsoluteMagnitudeOfDifference(), ns3::LollipopCounter< T >::m_circularRegion, ns3::LollipopCounter< T >::m_sequenceWindow, ns3::LollipopCounter< T >::m_value, and NS_ABORT_MSG_IF.

Referenced by LollipopCounterTest::DoRun().

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◆ IsInit()

template<class T >

bool ns3::LollipopCounter< T >::IsInit ( ) const

inline

Checks if a counter is in its starting region.

Returns: true if a counter is in its starting region.

Definition at line 172 of file lollipop-counter.h.

References ns3::LollipopCounter< T >::m_circularRegion, and ns3::LollipopCounter< T >::m_value.

◆ operator=()

template<class T >

LollipopCounter & ns3::LollipopCounter< T >::operator= ( const LollipopCounter< T > & o )

inline

Assignment.

Parameters

[in] o Value to assign to this LollipopCounter.

Returns: This LollipopCounter.

Definition at line 98 of file lollipop-counter.h.

References ns3::LollipopCounter< T >::m_value.

◆ Reset()

template<class T >

void ns3::LollipopCounter< T >::Reset ( )

inline

Resets the counter to its initial value.

Definition at line 107 of file lollipop-counter.h.

References ns3::LollipopCounter< T >::m_maxValue, ns3::LollipopCounter< T >::m_sequenceWindow, and ns3::LollipopCounter< T >::m_value.

◆ SetSequenceWindowSize()

template<class T >

void ns3::LollipopCounter< T >::SetSequenceWindowSize ( uint16_t numberOfBits )

inline

Set the Sequence Window Size and resets the counter.

The sequence window is equal to 2^numberOfBits. The counter is reset to maxValue - m_sequenceWindow +1, where maxValue is the maximum number allowed by the underlying type.

Parameters

numberOfBits number of bits to use in the Sequence Window

Definition at line 121 of file lollipop-counter.h.

References ns3::LollipopCounter< T >::m_maxValue, ns3::LollipopCounter< T >::m_sequenceWindow, ns3::LollipopCounter< T >::m_value, and NS_ABORT_MSG_IF.

Friends And Related Symbol Documentation

◆ operator++ [1/2]

template<class T >

LollipopCounter operator++ ( LollipopCounter< T > & val )

friend

Prefix increment operator.

Parameters

[in] val LollipopCounter to be incremented

Returns: The result of the Prefix increment.

Definition at line 284 of file lollipop-counter.h.

◆ operator++ [2/2]

template<class T >

LollipopCounter operator++	(	LollipopCounter< T > &	val,
		int	noop )

friend

Postfix increment operator.

Parameters

[in]	val	LollipopCounter to be incremented
[in]	noop	ignored argument (used to mark it as a postfix, blame c++).

Returns: The result of the Postfix increment.

Definition at line 302 of file lollipop-counter.h.

◆ operator<

template<class T >

bool operator<	(	const LollipopCounter< T > &	lhs,
		const LollipopCounter< T > &	rhs )

friend

Arithmetic operator less-than.

Parameters

[in]	lhs	Left hand argument
[in]	rhs	Right hand argument

Returns: The result of the operator.

Definition at line 264 of file lollipop-counter.h.

◆ operator<<

template<class T >

std::ostream & operator<<	(	std::ostream &	os,
		const LollipopCounter< T > &	counter )

friend

Output streamer for LollipopCounter.

Parameters

[in,out]	os	The output stream.
[in]	counter	The LollipopCounter to print.

Returns: The stream.

Definition at line 326 of file lollipop-counter.h.

◆ operator==

template<class T >

bool operator==	(	const LollipopCounter< T > &	lhs,
		const LollipopCounter< T > &	rhs )

friend

Arithmetic operator equal-to.

Parameters

[in]	lhs	Left hand argument
[in]	rhs	Right hand argument

Returns: The result of the operator.

Definition at line 183 of file lollipop-counter.h.

◆ operator>

template<class T >

bool operator>	(	const LollipopCounter< T > &	lhs,
		const LollipopCounter< T > &	rhs )

friend

Arithmetic operator greater-than.

Parameters

[in]	lhs	Left hand argument
[in]	rhs	Right hand argument

Returns: The result of the operator.

Definition at line 197 of file lollipop-counter.h.

Member Data Documentation

◆ m_circularRegion

template<class T >

T ns3::LollipopCounter< T >::m_circularRegion = m_maxValue >> 1

staticconstexprprivate

Circular region of the counter.

Definition at line 364 of file lollipop-counter.h.

Referenced by ns3::LollipopCounter< T >::AbsoluteMagnitudeOfDifference(), ns3::LollipopCounter< T >::IsComparable(), and ns3::LollipopCounter< T >::IsInit().

◆ m_maxValue

template<class T >

T ns3::LollipopCounter< T >::m_maxValue

staticconstexprprivate

Initial value:

=

std::numeric_limits<T>::max()

Maximum value of the counter.

Definition at line 362 of file lollipop-counter.h.

Referenced by ns3::LollipopCounter< T >::LollipopCounter(), ns3::LollipopCounter< T >::Reset(), and ns3::LollipopCounter< T >::SetSequenceWindowSize().

◆ m_sequenceWindow

template<class T >

T ns3::LollipopCounter< T >::m_sequenceWindow

private

Sequence window used for comparing two counters.

Definition at line 361 of file lollipop-counter.h.

Referenced by ns3::LollipopCounter< T >::LollipopCounter(), ns3::LollipopCounter< T >::LollipopCounter(), ns3::LollipopCounter< T >::IsComparable(), ns3::LollipopCounter< T >::Reset(), and ns3::LollipopCounter< T >::SetSequenceWindowSize().

◆ m_value

template<class T >

T ns3::LollipopCounter< T >::m_value

private

Value of the Lollipop Counter.

Definition at line 360 of file lollipop-counter.h.

Referenced by ns3::LollipopCounter< T >::LollipopCounter(), ns3::LollipopCounter< T >::LollipopCounter(), ns3::LollipopCounter< T >::AbsoluteMagnitudeOfDifference(), ns3::LollipopCounter< T >::GetValue(), ns3::LollipopCounter< T >::IsComparable(), ns3::LollipopCounter< T >::IsInit(), ns3::LollipopCounter< T >::operator=(), ns3::LollipopCounter< T >::Reset(), and ns3::LollipopCounter< T >::SetSequenceWindowSize().

The documentation for this class was generated from the following file:

src/network/utils/lollipop-counter.h

Public Member Functions

Private Member Functions

Private Attributes

Static Private Attributes

Friends

Detailed Description

Constructor & Destructor Documentation

◆ LollipopCounter() [1/2]

◆ LollipopCounter() [2/2]

Member Function Documentation

◆ AbsoluteMagnitudeOfDifference()

◆ GetValue()

◆ IsComparable()

◆ IsInit()

◆ operator=()

◆ Reset()

◆ SetSequenceWindowSize()

Friends And Related Symbol Documentation

◆ operator++ [1/2]

◆ operator++ [2/2]

◆ operator<

◆ operator<<

◆ operator==

◆ operator>

Member Data Documentation

◆ m_circularRegion

◆ m_maxValue

◆ m_sequenceWindow

◆ m_value