Struct CountMinSketch 

pub struct CountMinSketch { /* private fields */ }

Count-Min Sketch for approximate frequency estimation.

Uses depth independent hash functions (derived from a single hash via mixing) and width counters per row. Each counter is a u8 saturating at CountMinSketch::MAX_COUNT (15 by default, representing 4-bit counters).

Error Bounds

For a sketch with width w and depth d, after N total increments:

• estimate(x) <= true_count(x) + epsilon * N with probability >= 1 - delta
• where epsilon = e / w and delta = (1/2)^d

Implementations

impl CountMinSketch

pub fn new(width: usize, depth: usize, reset_interval: u64) -> Self

Create a new Count-Min Sketch with the given dimensions.

pub fn with_defaults() -> Self

Create a sketch with default parameters (w=1024, d=4, reset=8192).

pub fn increment(&mut self, hash: u64) -> bool

Increment the count for a key.

Returns true if this increment triggered the periodic aging reset (all counters halved). Callers pairing the sketch with a Doorkeeper must clear the doorkeeper when this returns true, so the one-hit-wonder filter restarts with the new epoch.

pub fn estimate(&self, hash: u64) -> u8

Estimate the frequency of a key (minimum across all rows).

pub fn total_increments(&self) -> u64

Total number of increments since creation or last reset.

pub fn clear(&mut self)

Clear all counters to zero.

Trait Implementations

impl Clone for CountMinSketch

fn clone(&self) -> CountMinSketch

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for CountMinSketch

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

Formats the value using the given formatter.