kumulant
com.eignex.kumulant/stat/sketch/HeavyHittersResult

HeavyHittersResult

@Serializable
@SerialName(value = "HeavyHittersResult")
data class HeavyHittersResult(val capacity: Int, val keys: LongArray, val counts: LongArray, val errors: LongArray, val totalSeen: Long, val policy: AdmissionPolicy = AdmissionPolicy.Classic, val deficit: Long = 0) : HasObservationCount(source)

Space-Saving heavy-hitters snapshot. keys, counts, errors are parallel arrays of length <= capacity. totalSeen is the unweighted update count.

The true weighted count of a tracked key lies in [counts[i] - errors[i], counts[i] + deficit]. Each bound closes one direction, and which one is slack depends on policy:

  • Under AdmissionPolicy.Classic a count can only overestimate. errors carries the per-key bound inherited from the evicted minimum, and deficit is zero.

  • Under AdmissionPolicy.MisraGries a count can only underestimate, because it is only ever incremented exactly or decremented in bulk. errors is zero - correctly, not for want of a bound - and deficit carries the number of decrement rounds, which bounds the shortfall for every key.

A merge that mixes the two accumulates deficit and degrades policy, so both bounds stay sound.

Constructors

HeavyHittersResult

constructor(capacity: Int, keys: LongArray, counts: LongArray, errors: LongArray, totalSeen: Long, policy: AdmissionPolicy = AdmissionPolicy.Classic, deficit: Long = 0)(source)

Properties

capacity

val capacity: Int(source)

counts

val counts: LongArray(source)

deficit

val deficit: Long(source)

Bulk-decrement rounds absorbed; bounds how far any count may fall below the true count.

errors

val errors: LongArray(source)

keys

val keys: LongArray(source)

policy

val policy: AdmissionPolicy(source)

Which algorithm produced these counts, and so which direction their slack runs in.

totalSeen

val totalSeen: Long(source)

totalWeights

open override val totalWeights: Double(source)

Cumulative weight of observations folded into this result.

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open val isEmpty: Boolean

True when no observation has been folded in, so every other field is a placeholder.

Functions

equals

open operator override fun equals(other: Any?): Boolean(source)

hashCode

open override fun hashCode(): Int(source)

toString

open override fun toString(): String(source)