Class: ThrottleMachines::Limiter

Inherits:
Object
  • Object
show all
Defined in:
lib/throttle_machines/limiter.rb

Direct Known Subclasses

AsyncLimiter

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(key, limit:, period:, algorithm: :fixed_window, storage: nil) ⇒ Limiter

Returns a new instance of Limiter.



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# File 'lib/throttle_machines/limiter.rb', line 7

def initialize(key, limit:, period:, algorithm: :fixed_window, storage: nil)
  @key = key
  @limit = limit
  @period = period
  @algorithm = algorithm
  @storage = storage || ThrottleMachines.storage
end

Instance Attribute Details

#algorithm ⇒ Object (readonly)

Returns the value of attribute algorithm.



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# File 'lib/throttle_machines/limiter.rb', line 5

def algorithm
  @algorithm
end

#key ⇒ Object (readonly)

Returns the value of attribute key.



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# File 'lib/throttle_machines/limiter.rb', line 5

def key
  @key
end

#limit ⇒ Object (readonly)

Returns the value of attribute limit.



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# File 'lib/throttle_machines/limiter.rb', line 5

def limit
  @limit
end

#period ⇒ Object (readonly)

Returns the value of attribute period.



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# File 'lib/throttle_machines/limiter.rb', line 5

def period
  @period
end

#storage ⇒ Object (readonly)

Returns the value of attribute storage.



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# File 'lib/throttle_machines/limiter.rb', line 5

def storage
  @storage
end

Instance Method Details

#allow? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/throttle_machines/limiter.rb', line 15

def allow?
  allowed = case @algorithm
            when :fixed_window
              # Don't increment here, just check
              count = @storage.get_counter(@key, @period)
              count < @limit
            when :gcra
              result = @storage.peek_gcra_limit(
                @key,
                @period.to_f / @limit,  # emission_interval
                0                       # delay_tolerance (no burst)
              )
              result[:allowed]
            when :token_bucket
              result = @storage.peek_token_bucket(
                @key,
                @limit,                 # capacity
                @limit.to_f / @period   # refill_rate
              )
              result[:allowed]
            else
              raise ArgumentError, "Unknown algorithm: #{@algorithm}"
            end

  # Instrument the check
  Instrumentation.rate_limit_checked(self, allowed: allowed, remaining: nil)

  allowed
end

#remaining ⇒ Object 



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# File 'lib/throttle_machines/limiter.rb', line 101

def remaining
  case @algorithm
  when :fixed_window
    count = @storage.get_counter(@key, @period)
    [@limit - count, 0].max
  when :gcra
    # GCRA doesn't have a simple "remaining" count
    # Just return 1 or 0 based on current state
    result = @storage.peek_gcra_limit(
      @key,
      @period.to_f / @limit,
      0
    )
    result[:allowed] ? 1 : 0
  when :token_bucket
    result = @storage.peek_token_bucket(
      @key,
      @limit,
      @limit.to_f / @period
    )
    result[:tokens_remaining].to_i
  else
    0
  end
end

#reset! ⇒ Object 



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# File 'lib/throttle_machines/limiter.rb', line 92

def reset!
  case @algorithm
  when :fixed_window
    @storage.reset_counter(@key, @period)
  else
    @storage.clear("#{@key}*")
  end
end

#retry_after ⇒ Object 



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# File 'lib/throttle_machines/limiter.rb', line 127

def retry_after
  case @algorithm
  when :fixed_window
    count = @storage.get_counter(@key, @period)
    if count >= @limit
      # Return the actual time remaining in the current window
      @storage.get_counter_ttl(@key, @period)
    else
      0
    end
  when :gcra
    result = @storage.peek_gcra_limit(
      @key,
      @period.to_f / @limit,
      0
    )
    result[:retry_after]
  when :token_bucket
    result = @storage.peek_token_bucket(
      @key,
      @limit,
      @limit.to_f / @period
    )
    result[:retry_after]
  else
    0
  end
end

#throttle! ⇒ Object 



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# File 'lib/throttle_machines/limiter.rb', line 45

def throttle!
  case @algorithm
  when :fixed_window
    # Increment and check atomically
    count = @storage.increment_counter(@key, @period)
    if count > @limit
      Instrumentation.rate_limit_throttled(self, retry_after: retry_after)
      raise ThrottledError, self
    end
  when :gcra
    result = @storage.check_gcra_limit(
      @key,
      @period.to_f / @limit,  # emission_interval
      0,                      # delay_tolerance (no burst)
      (@period * 2).to_i      # ttl
    )
    unless result[:allowed]
      Instrumentation.rate_limit_throttled(self, retry_after: retry_after)
      raise ThrottledError, self
    end
  when :token_bucket
    result = @storage.check_token_bucket(
      @key,
      @limit,                 # capacity
      @limit.to_f / @period,  # refill_rate
      (@period * 2).to_i      # ttl
    )
    unless result[:allowed]
      Instrumentation.rate_limit_throttled(self, retry_after: retry_after)
      raise ThrottledError, self
    end
  else
    raise ArgumentError, "Unknown algorithm: #{@algorithm}"
  end

  # If we get here, the request was allowed
  # Calculate remaining after the operation
  remaining_count = begin
    remaining
  rescue StandardError
    nil
  end
  Instrumentation.rate_limit_allowed(self, remaining: remaining_count)

  yield if block_given?
end

#to_h ⇒ Object 



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# File 'lib/throttle_machines/limiter.rb', line 156

def to_h
  {
    key: @key,
    limit: @limit,
    period: @period,
    algorithm: @algorithm,
    remaining: remaining,
    retry_after: retry_after
  }
end