Struct CMSketchU32 

pub struct CMSketchU32 { /* private fields */ }

Count-Min Sketch storing non-atomic u32 counters.

Use CMSketchU32::new to size the table based on error (eps) and confidence requirements.

Implementations

impl CMSketchU32

pub fn new(eps: f64, confidence: f64) -> Self

Creates a new sketch sized by the target error eps and confidence.

eps controls the maximum additive error (≈ 2/width), while confidence determines the number of hash rows (depth).

Typical confidence to depth mapping:

0.50 => 1 row
0.80 => 3 rows
0.95 => 5 rows
0.995 => 8 rows

Panics

Panics if eps <= 0.0 or confidence <= 0.0.

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

Increments the count associated with the provided hash by 1.

pub fn inc_by(&mut self, hash: u64, count: u32)

Increments the count associated with the provided hash by count.

Saturates at the maximum value representable by the counter type.

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

Decrements the count associated with the provided hash by 1.

pub fn dec_by(&mut self, hash: u64, count: u32)

Decrements the count associated with the provided hash by count.

Saturates at zero if the counter would go negative.

pub fn estimate(&self, hash: u64) -> u32

Returns the minimum counter across all rows for hash.

This is the standard Count-Min Sketch estimator and forms an upper bound.

pub fn clear(&mut self)

Resets all counters to zero.

pub fn halve(&mut self)

Divides every counter by two using a right shift.

Useful for exponential decay where counts represent recent activity.

pub fn decay(&mut self, decay: f64)

Multiplies every counter by decay and truncates back into $type.

Values are floored after multiplication; choose decay in (0, 1].

pub fn width(&self) -> usize

Returns the configured table width (number of columns).

pub fn depth(&self) -> usize

Returns the number of hash rows.

pub fn capacity(&self) -> u32

Returns the maximum representable counter for this sketch.

pub fn memory(&self) -> usize

Returns the amount of memory the sketch uses in bytes.

Trait Implementations

impl Debug for CMSketchU32

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

Formats the value using the given formatter.