Struct xorf::Xor8 [−][src]
Expand description
Xor filter using 8-bit fingerprints.
An Xor8
filter uses <10 bits per entry of the set is it constructed from, and has a false
positive rate of <0.4%. As with other probabilistic filters, a higher number of entries decreases
the bits per entry but increases the false positive rate.
An Xor8
is constructed from a set of 64-bit unsigned integers and is immutable.
use xorf::{Filter, Xor8}; const SAMPLE_SIZE: usize = 1_000_000; let keys: Vec<u64> = (0..SAMPLE_SIZE).map(|_| rng.gen()).collect(); let filter = Xor8::from(&keys); // no false negatives for key in keys { assert!(filter.contains(&key)); } // bits per entry let bpe = (filter.len() as f64) * 8.0 / (SAMPLE_SIZE as f64); assert!(bpe < 10., "Bits per entry is {}", bpe); // false positive rate let false_positives: usize = (0..SAMPLE_SIZE) .map(|_| rng.gen()) .filter(|n| filter.contains(n)) .count(); let fp_rate: f64 = (false_positives * 100) as f64 / SAMPLE_SIZE as f64; assert!(fp_rate < 0.405, "False positive rate is {}", fp_rate);
Serializing and deserializing Xor8
filters can be enabled with the serde
feature.
Fields
seed: u64
The seed for the filter
block_length: usize
The number of blocks in the filter
fingerprints: Box<[u8]>
The fingerprints for the filter
Trait Implementations
Auto Trait Implementations
impl RefUnwindSafe for Xor8
impl UnwindSafe for Xor8