Class: Contrast::Utils::Assess::SamplingUtil

Inherits:
Object
  • Object
show all
Includes:
Components::Interface, Singleton
Defined in:
lib/contrast/utils/assess/sampling_util.rb

Overview

SamplingUtil has methods for tracking the number of requests per time window

Defined Under Namespace

Classes: RequestHistory

Instance Method Summary collapse

Methods included from Components::Interface

included

Constructor Details

#initialize ⇒ SamplingUtil

Returns a new instance of SamplingUtil.



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# File 'lib/contrast/utils/assess/sampling_util.rb', line 17

def initialize
  @requests = {}
end

Instance Method Details

#sample?(request) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/contrast/utils/assess/sampling_util.rb', line 32

def sample? request
  history = request_history(request)
  history.hit

  # if sampling isn't enabled, we record all requests and take a
  # default amount of responses
  return [true, true] unless @enabled

  # if we've exceeded this sample window, reset it
  if history.elapsed >= @window_ms
    history.reset_window
    return [true, true]
  end

  # we have to take a baseline of this request/ response combo. we only
  # baseline the first response, but we'll do full request analysis up
  # to the baseline amount
  return [true, history.window_hit == 1] if history.window_hit < @baseline

  # Once the window_hit exceeds the baseline, we limit the analysis
  # based on @request_frequency and @response_frequency.
  non_baseline = history.window_hit - @baseline
  analyze_request = (non_baseline % @request_frequency).zero?
  analyze_response = (non_baseline % @response_frequency).zero?

  [analyze_request, analyze_response]
end

#update ⇒ Object 



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# File 'lib/contrast/utils/assess/sampling_util.rb', line 21

def update
  self.class.reset_sampling_control
  @enabled            = self.class.sampling_enabled?
  @baseline           = self.class.sampling_control[:baseline]
  @request_frequency  = self.class.sampling_control[:request_frequency]
  @response_frequency = self.class.sampling_control[:response_frequency]
  @window_ms          = self.class.sampling_control[:window]

  true
end