Struct HeavyHitters 

pub struct HeavyHitters { /* private fields */ }

Top-k frequent-value sketch.

Implementations

impl HeavyHitters

pub fn new(name: impl Into<String>) -> HeavyHitters

Create a heavy-hitters index with the default CMS size and [DEFAULT_K].

pub fn with_params( name: impl Into<String>, k: usize, cms_width: usize, cms_depth: usize, ) -> HeavyHitters

Fully-configurable constructor. k is the top-k size, width/depth size the CMS (more width = tighter estimates).

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

Record one observation of key. Frequency estimate and top-k cache are updated atomically — callers never see a stale state.

pub fn observe_n(&mut self, key: &[u8], count: u64)

Record count observations of key. Bulk-load variant.

pub fn top_k(&self) -> Vec<(Vec<u8>, u64)>

Return the current top-k entries, highest frequency first.

pub fn estimate(&self, key: &[u8]) -> u64

Estimate the frequency of a single key (never underestimates).

pub fn total_observed(&self) -> u64

Total number of observations recorded (including keys outside the top-k).

pub fn relative_frequency(&self, key: &[u8]) -> f64

Relative frequency of key as a fraction of all observations. Returns 0.0 for an empty sketch.

pub fn k(&self) -> usize

Configured top-k capacity.

pub fn clear(&mut self)

Reset the sketch and the top-k cache.

Trait Implementations

impl IndexBase for HeavyHitters

fn name(&self) -> &str

Human-readable name (e.g. “users.email”, “graph.city_by_node”).

fn kind(&self) -> IndexKind

Index family (btree, hash, bitmap, hnsw, …).

fn stats(&self) -> IndexStats

Current statistics (cardinality, estimated selectivity, memory).

fn bloom(&self) -> Option<&BloomFilter>

Optional bloom filter for fast negative lookups. Cross-structure pruning relies on this.

fn definitely_absent(&self, key_bytes: &[u8]) -> bool

Returns true iff the key is guaranteed to be absent from this index. Default implementation consults IndexBase::bloom and falls back to false when no bloom is available (meaning “don’t know — caller must probe”).