bloom

Documentation

Overview

Package bloom implements a Bloom Filter.

Index

• func DeriveSize(n int, p float64) int
• type Filter
  • func New(rand io.Reader, mLn2 int, p float64) (*Filter, error)
  • func (f *Filter) Entries() int
  • func (f *Filter) MaxEntries() int
  • func (f *Filter) Test(b []byte) bool
  • func (f *Filter) TestAndSet(b []byte) bool

Functions

func DeriveSize

func DeriveSize(n int, p float64) int

DeriveSize returns the size of a filter (as a power of 2) in bits, required to hold at least n entries with a p false positive rate.

The returned value is directly suitable for use as the mLn2 parameter passed to New().

Types

type Filter

type Filter struct {
	// contains filtered or unexported fields
}

Filter is a bloom filter.

func New

func New(rand io.Reader, mLn2 int, p float64) (*Filter, error)

New constructs a new Filter with a filter set size 2^mLn2 bits, and false postive rate p.

func (*Filter) Entries

func (f *Filter) Entries() int

Entries returns the number of entries that have been inserted into the Filter.

func (*Filter) MaxEntries

func (f *Filter) MaxEntries() int

MaxEntries returns the maximum capacity of the Filter.

func (*Filter) Test

func (f *Filter) Test(b []byte) bool

Test tests the Filter for a given value's membership and returns true iff it is present (or a false positive).

func (*Filter) TestAndSet

func (f *Filter) TestAndSet(b []byte) bool

TestAndSet tests the Filter for a given value's membership, adds the value to the filter, and returns true iff it was present at the time of the call.