Struct CountingBloomFilter 

pub struct CountingBloomFilter { /* private fields */ }

Bloom filter with 4-bit saturating counters that supports deletion.

Each logical bit-position in the standard filter is replaced by a 4-bit counter stored in nibbles (two counters per byte). A counter saturates at 15 to prevent overflow; decrement is a no-op on saturated counters (a conservative choice that avoids spurious false-negatives).

Implementations

impl CountingBloomFilter

pub fn new(expected_items: usize, false_positive_rate: f64) -> Self

Construct a new CountingBloomFilter optimised for the given parameters.

pub fn insert(&mut self, item: &[u8])

Insert item into the filter, incrementing all associated counters.

pub fn contains(&self, item: &[u8]) -> bool

Return true if item may be in the set.

pub fn remove(&mut self, item: &[u8]) -> bool

Attempt to remove item from the filter by decrementing all associated counters.

Returns true if the item was (probably) present and all counters could be safely decremented. Returns false if any counter was already zero (item was never inserted, or already removed) or if any counter is saturated (the decrement is withheld).

pub fn item_count(&self) -> u64

Return the number of items currently represented in the filter.

pub fn estimate_false_positive_rate(&self) -> f64

Estimate false-positive rate (same formula as BloomFilter).

Trait Implementations

impl Clone for CountingBloomFilter

fn clone(&self) -> CountingBloomFilter

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for CountingBloomFilter

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.