Struct xorfilter::Xor8

pub struct Xor8<H = BuildHasherDefault> where
    H: BuildHasher,  {
    pub hash_builder: H,
    pub seed: u64,
    pub block_length: u32,
    pub finger_prints: Vec<u8>,
    // some fields omitted
}

Type Xor8 is probabilistic data-structure to test membership of an element in a set.

This implementation has a false positive rate of about 0.3% and a memory usage of less than 9 bits per entry for sizeable sets. Xor8 is parametrized over type H which is expected to implement BuildHasher trait, like RandomState and BuildHasherDefault. When not supplied, BuildHasherDefault is used as the default hash-builder. When applications want to serialize and de-serialize Xor8, avoid using RandomState.

Fields

hash_builder: H

seed: u64

block_length: u32

finger_prints: Vec<u8>

Implementations

impl<H> Xor8<H> where
    H: Default + BuildHasher, 

pub fn new() -> Self

New Xor8 instance initialized with DefaultHasher.

impl<H> Xor8<H> where
    H: BuildHasher, 

pub fn with_hasher(hash_builder: H) -> Self

New Xor8 instance initialized with supplied hasher.

pub fn insert<T: ?Sized + Hash>(&mut self, key: &T)

Insert 64-bit digest of a single key. Digest for the key shall be generated using the default-hasher or via hasher supplied via Xor8::with_hasher method.

pub fn populate<T: Hash>(&mut self, keys: &[T])

Populate 64-bit digests for collection of keys. Digest for the key shall be generated using the default-hasher or via hasher supplied via Xor8::with_hasher method.

pub fn populate_keys(&mut self, keys: &[u64])

Populate pre-compute 64-bit digests for keys.

pub fn build(&mut self)

Build bitmap for keys that are insert using Xor8::insert or Xor8::populate method.

pub fn build_keys(&mut self, keys: &[u64])

Build a bitmap for pre-computed 64-bit digests for keys. If any keys where inserted using Xor8::insert, Xor8::populate, Xor8::populate_keys method shall be ignored.

pub fn contains<T: ?Sized + Hash>(&self, key: &T) -> bool

Contains tell you whether the key is likely part of the set.

pub fn contains_key(&self, key: u64) -> bool

impl<H> Xor8<H> where
    H: BuildHasher, 

pub fn write_file(&self, path: &OsStr) -> Result<usize>

Write to file in binary format TODO Add chechsum of finger_prints into file headers

pub fn read_file(path: &OsStr) -> Result<Self> where
    H: Default, 

Read from file in binary format

pub fn to_bytes(&self) -> Vec<u8>

pub fn from_bytes(buf: Vec<u8>) -> Result<Self> where
    H: Default, 

Trait Implementations

impl<H> Default for Xor8<H> where
    H: BuildHasher + Default, 

fn default() -> Self

Returns the “default value” for a type.

impl<H> PartialEq<Xor8<H>> for Xor8<H> where
    H: BuildHasher, 

fn eq(&self, other: &Self) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]pub fn ne(&self, other: &Rhs) -> bool

This method tests for !=.