GCSFilter Class Reference

This implements a Golomb-coded set as defined in BIP 158. More...

#include <blockfilter.h>

Collaboration diagram for GCSFilter:

Classes
struct	Params

Public Types
typedef std::vector< unsigned char >	Element
typedef std::unordered_set< Element, ByteVectorHash >	ElementSet

Public Member Functions
	GCSFilter (const Params &params=Params())
	Constructs an empty filter. More...
	GCSFilter (const Params &params, std::vector< unsigned char > encoded_filter, bool skip_decode_check)
	Reconstructs an already-created filter from an encoding. More...
	GCSFilter (const Params &params, const ElementSet &elements)
	Builds a new filter from the params and set of elements. More...
uint32_t	GetN () const
const Params &	GetParams () const LIFETIMEBOUND
const std::vector< unsigned char > &	GetEncoded () const LIFETIMEBOUND
bool	Match (const Element &element) const
	Checks if the element may be in the set. More...
bool	MatchAny (const ElementSet &elements) const
	Checks if any of the given elements may be in the set. More...

Private Member Functions
uint64_t	HashToRange (const Element &element) const
	Hash a data element to an integer in the range [0, N * M). More...
std::vector< uint64_t >	BuildHashedSet (const ElementSet &elements) const
bool	MatchInternal (const uint64_t *sorted_element_hashes, size_t size) const
	Helper method used to implement Match and MatchAny. More...

Private Attributes
Params	m_params
uint32_t	m_N
	Number of elements in the filter. More...
uint64_t	m_F
	Range of element hashes, F = N * M. More...
std::vector< unsigned char >	m_encoded

Detailed Description

This implements a Golomb-coded set as defined in BIP 158.

It is a compact, probabilistic data structure for testing set membership.

Definition at line 28 of file blockfilter.h.

Member Typedef Documentation

Element

typedef std::vector<unsigned char> GCSFilter::Element

Definition at line 31 of file blockfilter.h.

ElementSet

typedef std::unordered_set<Element, ByteVectorHash> GCSFilter::ElementSet

Definition at line 32 of file blockfilter.h.

Constructor & Destructor Documentation

GCSFilter() [1/3]

GCSFilter::GCSFilter ( const Params &  params = Params() )

explicit

Constructs an empty filter.

Definition at line 44 of file blockfilter.cpp.

GCSFilter() [2/3]

GCSFilter::GCSFilter	(	const Params &	params,
		std::vector< unsigned char >	encoded_filter,
		bool	skip_decode_check
	)

Reconstructs an already-created filter from an encoding.

Definition at line 48 of file blockfilter.cpp.

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GCSFilter() [3/3]

GCSFilter::GCSFilter	(	const Params &	params,
		const ElementSet &	elements
	)

Builds a new filter from the params and set of elements.

Definition at line 73 of file blockfilter.cpp.

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Member Function Documentation

BuildHashedSet()

std::vector< uint64_t > GCSFilter::BuildHashedSet ( const ElementSet &  elements ) const

private

Definition at line 33 of file blockfilter.cpp.

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GetEncoded()

const std::vector< unsigned char > & GCSFilter::GetEncoded ( ) const

inline

Definition at line 73 of file blockfilter.h.

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GetN()

uint32_t GCSFilter::GetN ( ) const

inline

Definition at line 71 of file blockfilter.h.

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GetParams()

const Params & GCSFilter::GetParams ( ) const

inline

Definition at line 72 of file blockfilter.h.

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HashToRange()

uint64_t GCSFilter::HashToRange ( const Element &  element ) const

private

Hash a data element to an integer in the range [0, N * M).

Definition at line 25 of file blockfilter.cpp.

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Match()

bool GCSFilter::Match

(

const Element &

element

)

const

Checks if the element may be in the set.

False positives are possible with probability 1/M.

Definition at line 135 of file blockfilter.cpp.

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MatchAny()

bool GCSFilter::MatchAny

(

const ElementSet &

elements

)

const

Checks if any of the given elements may be in the set.

False positives are possible with probability 1/M per element checked. This is more efficient that checking Match on multiple elements separately.

Definition at line 141 of file blockfilter.cpp.

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MatchInternal()

bool GCSFilter::MatchInternal ( const uint64_t *  sorted_element_hashes, size_t  size  ) const

private

Helper method used to implement Match and MatchAny.

Definition at line 103 of file blockfilter.cpp.

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Member Data Documentation

m_encoded

std::vector<unsigned char> GCSFilter::m_encoded

private

Definition at line 50 of file blockfilter.h.

m_F

uint64_t GCSFilter::m_F

private

Range of element hashes, F = N * M.

Definition at line 49 of file blockfilter.h.

m_N

uint32_t GCSFilter::m_N

private

Number of elements in the filter.

Definition at line 48 of file blockfilter.h.

m_params

Params GCSFilter::m_params

private

Definition at line 47 of file blockfilter.h.

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

• src/blockfilter.h
• src/blockfilter.cpp