Struct HyperLogLog 

pub struct HyperLogLog { /* private fields */ }

Probabilistic distinct-count sketch.

Examples

use anomstream_core::HyperLogLog;

let mut hll = HyperLogLog::with_default_precision();
for ip in 0..10_000_u32 {
    hll.add(&ip.to_le_bytes());
}
let est = hll.estimate();
let err = (est as i64 - 10_000).unsigned_abs() as f64 / 10_000.0;
assert!(err < 0.05); // 3× the theoretical 1.625 % — conservative

Implementations

impl HyperLogLog

pub fn new(precision: u8) -> RcfResult<Self>

Build a sketch with caller-chosen precision.

Errors

Returns RcfError::InvalidConfig when precision is outside [MIN_PRECISION, MAX_PRECISION].

pub fn with_default_precision() -> Self

Default sketch — p = 12, 4 096 registers, ≈ 1.625 % std error, ~4 KiB memory.

Panics

Never in practice — DEFAULT_PRECISION is a compile-time constant validated against the [MIN, MAX] range.

pub fn register_count(&self) -> usize

Register count m = 2^p.

pub fn precision(&self) -> u8

Precision bit count.

pub fn total_added(&self) -> u64

Total values passed through Self::add.

pub fn memory_bytes(&self) -> usize

Memory footprint in bytes (register bank only).

pub fn add<T: Hash + ?Sized>(&mut self, value: &T)

Ingest a Hash-able value. Pre-hashes through DefaultHasher (SipHash) so per-key distribution is uniform irrespective of the user type’s own Hash impl quality.

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

Ingest a raw byte key. Cheaper when the caller already has a fixed-size fingerprint (e.g. [u8; 16] IP, flow-hash tuple) — skips the generic Hash dispatch.

pub fn add_hash(&mut self, hash: u64)

Ingest a caller-supplied 64-bit hash. Escape hatch for callers with a stronger hasher (e.g. xxhash, siphash with a keyed seed) — the sketch’s accuracy depends on hash % 2^p being uniform.

pub fn estimate(&self) -> u64

Cardinality estimate — number of distinct values ingested.

pub fn merge(&mut self, other: &Self) -> RcfResult<()>

Fold other into self by taking a per-register maximum. Two sketches must share the same precision — HLL merge is the whole reason the sketch is decomposable across shards / time windows.

Errors

Returns RcfError::InvalidConfig when the two sketches disagree on precision.

pub fn reset(&mut self)

Zero every register. Allocation is preserved.

Trait Implementations

impl Clone for HyperLogLog

fn clone(&self) -> HyperLogLog

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for HyperLogLog

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for HyperLogLog

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for HyperLogLog

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.