Class: Vines::TokenBucket

Inherits:
Object
  • Object
show all
Defined in:
lib/vines/token_bucket.rb

Overview

The token bucket algorithm is useful for rate limiting. Before an operation can be completed, a token is taken from the bucket. If no tokens are available, the operation fails. The bucket is refilled with tokens at the maximum allowed rate of operations.

Instance Method Summary collapse

Constructor Details

#initialize(capacity, rate) ⇒ TokenBucket

Create a full bucket with capacity number of tokens to be filled at the given rate of tokens/second.

Raises:

  • (ArgumentError) 


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# File 'lib/vines/token_bucket.rb', line 14

def initialize(capacity, rate)
  raise ArgumentError.new('capacity must be > 0') unless capacity > 0
  raise ArgumentError.new('rate must be > 0') unless rate > 0
  @capacity = capacity
  @tokens = capacity
  @rate = rate
  @timestamp = Time.new
end

Instance Method Details

#take(tokens) ⇒ Object

Returns true if tokens can be taken from the bucket.

Raises:

  • (ArgumentError) 


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# File 'lib/vines/token_bucket.rb', line 24

def take(tokens)
  raise ArgumentError.new('tokens must be > 0') unless tokens > 0
  if tokens <= fill
    @tokens -= tokens
    true
  else
    false
  end
end