Struct bitcoin_bloom::RollingBloomFilter

pub struct RollingBloomFilter { /* private fields */ }

| RollingBloomFilter is a probabilistic “keep | track of most recently inserted” set. | Construct it with the number of items to keep | track of, and a false-positive rate. Unlike | CBloomFilter, by default nTweak is set to | a cryptographically secure random value for | you. Similarly rather than clear() the method | reset() is provided, which also changes nTweak | to decrease the impact of false-positives. | | contains(item) will always return true if item | was one of the last N to 1.5*N insert()’ed | … but may also return true for items that | were not inserted. | | It needs around 1.8 bytes per element per | factor 0.1 of false positive rate. | | For example, if we want 1000 elements, we’d | need: | | - ~1800 bytes for a false positive rate of 0.1 | - ~3600 bytes for a false positive rate of 0.01 | - ~5400 bytes for a false positive rate of 0.001 | | If we make these simplifying assumptions: | | - logFpRate / log(0.5) doesn’t get rounded or | clamped in the nHashFuncs calculation | | - nElements is even, so that | nEntriesPerGeneration == nElements / 2 | | Then we get a more accurate estimate for filter | bytes: | | 3/(log(256)*log(2)) * log(1/fpRate) * nElements

Implementations

impl RollingBloomFilter

pub fn new(n_elements: u32, fp_rate: f64) -> Self

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

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

pub fn reset(&mut self)