Struct RotatingBloomFilter

pub struct RotatingBloomFilter { /* private fields */ }

A probabilistic data structure that rotates out old items to maintain recent membership.

RotatingBloomFilter provides membership testing for recently inserted items, with older items automatically rotating out. Items are guaranteed to be retained for at least the minimum retention period, and typically remain for up to twice that duration.

Uses a dual-buffer rotation mechanism where items are added to both buffers, and periodically the older buffer is discarded, causing old items to rotate out.

Examples

let mut filter = RotatingBloomFilter::new(0.001, 1000, &mut OsRng);
filter.insert("hello");
assert!(filter.contains("hello"));
// After 2000 more insertions, "hello" will rotate out

Implementations

impl RotatingBloomFilter

pub fn new( false_pos: f64, min_retention: usize, csprng: &mut impl RngCore, ) -> Self

Creates a new RotatingBloomFilter with a given false positive rate and minimum retention period.

pub fn insert(&mut self, value: &(impl Hash + ?Sized)) -> (bool, bool)

Inserts an item into the rotating filter.

Items are guaranteed to be retained for at least the minimum retention period, typically remaining for up to twice that duration before rotating out.

Returns a tuple: (was_in_current, was_in_next)

pub fn contains(&self, value: &(impl Hash + ?Sized)) -> bool

Tests whether an item might be present in the current rotation.

May return false positives but never false negatives.