Module: CMDx::Limiters::LeakyBucket Private

Extended by:
LeakyBucket
Included in:
LeakyBucket
Defined in:
lib/cmdx/limiters/leaky_bucket.rb

Overview

This module is part of a private API. You should avoid using this module if possible, as it may be removed or be changed in the future.

Continuous leaky bucket backed by a single store key (store_key:lb). Leaks one unit every per seconds; admits when level + cost <= max.

Instance Method Summary collapse

Instance Method Details

#call(quota) ⇒ RateLimit::Admission

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Parameters:

Returns:



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# File 'lib/cmdx/limiters/leaky_bucket.rb', line 15

def call(quota)
  state_key = "#{quota.store_key}:lb"
  now       = Time.now.to_f
  level, last_at = parse_state(Stores.get(state_key), now)

  leaked = (now - last_at) / quota.per
  if leaked.positive?
    level -= leaked
    level = 0.0 if level.negative?
  end

  cost      = quota.cost
  capacity  = quota.max
  projected = level + cost
  admitted  = projected <= capacity

  level = projected if admitted

  Stores.set(state_key, "#{level}:#{now}", ttl: bucket_ttl(quota))

  retry_after =
    unless admitted
      overflow = projected - capacity
      overflow = 0 if overflow.negative?
      (overflow * quota.per).ceil
    end

  RateLimit::Admission.new(
    admitted:,
    count: nil,
    level:,
    retry_after:,
    limiter: :leaky_bucket
  )
end