Struct BloomPrescreen 

pub struct BloomPrescreen {
    pub bits: Vec<u64>,
    pub k_hashes: u32,
    pub num_bits: usize,
    /* private fields */
}

Bloom filter optimised for deduplication pre-screening.

Example

use oximedia_dedup::bloom_prescreen::BloomPrescreen;

let mut bp = BloomPrescreen::new(1000, 0.01);
bp.insert(b"hello");
assert!(bp.might_contain(b"hello"));
assert!(!bp.might_contain(b"world")); // (with high probability)

Fields

bits: Vec<u64>

Underlying bit storage (each u64 holds 64 bits).

k_hashes: u32

Number of independent hash functions.

num_bits: usize

Total number of addressable bits.

Implementations

impl BloomPrescreen

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

Create a new BloomPrescreen sized for capacity expected items at the given false_positive_rate.

Uses the standard formulas:

• m = ceil(-n * ln(p) / (ln 2)^2) (number of bits)
• k = round((m / n) * ln 2) (number of hash functions)

Both values are clamped to sensible minimums.

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

Insert key into the filter.

After calling this, might_contain will always return true for the same key (no false negatives).

pub fn might_contain(&self, key: &[u8]) -> bool

Returns true if key might be in the set (possible false positive). Returns false if key is definitely not in the set.

pub fn false_positive_rate_estimate(&self) -> f64

Estimate the current false-positive rate given the number of inserted items.

Formula: (1 - e^(-k * n / m))^k

Returns 1.0 when the filter is full.

pub fn items_inserted(&self) -> u64

Number of items inserted so far.

pub fn clear(&mut self)

Reset the filter to its initial empty state.

pub fn set_bit_count(&self) -> u64

Number of set bits (useful for diagnostics).

Trait Implementations

impl Clone for BloomPrescreen

fn clone(&self) -> BloomPrescreen

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for BloomPrescreen

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

Formats the value using the given formatter.