Limen.Sketch.RotatingBloom (limen v0.2.1)

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"Seen recently" as two Bloom filter generations.

Keys are added to the current generation and looked up in both. Rotating clears the older generation and makes it current, so a key is remembered for at least one full rotation period and at most two, in fixed memory and without per-key expiry.

Summary

Types

t()

Functions

member?(filter, key)

Whether key was seen recently.

new(capacity, false_positive_rate)

Creates a filter remembering capacity keys per generation.

put_new(filter, key)

Adds key unless it was seen recently. Returns true if it was new.

put_new_hash(filter, hash)

put_new/2 for a key hashed with Limen.Sketch.Bloom.hash/1 or Limen.Sketch.Bloom.hash_once/1.

rotate(filter)

Forgets the older generation and starts a new one.

Types

t()

@type t() :: %Limen.Sketch.RotatingBloom{
  cursor: :atomics.atomics_ref(),
  generations: {Limen.Sketch.Bloom.t(), Limen.Sketch.Bloom.t()}
}

Functions

member?(filter, key)

@spec member?(t(), term()) :: boolean()

Whether key was seen recently.

new(capacity, false_positive_rate)

@spec new(pos_integer(), float()) :: t()

Creates a filter remembering capacity keys per generation.

put_new(filter, key)

@spec put_new(t(), term()) :: boolean()

Adds key unless it was seen recently. Returns true if it was new.

put_new_hash(filter, hash)

@spec put_new_hash(t(), Limen.Sketch.Bloom.hash()) :: boolean()

put_new/2 for a key hashed with Limen.Sketch.Bloom.hash/1 or Limen.Sketch.Bloom.hash_once/1.

rotate(filter)

@spec rotate(t()) :: :ok

Forgets the older generation and starts a new one.