Class: Fino::AbTesting::VariantPicker

Inherits:
Object
  • Object
show all
Defined in:
lib/fino/ab_testing/variant_picker.rb

Constant Summary collapse

SCALING_FACTOR = 
1_000

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(setting_definition) ⇒ VariantPicker

Returns a new instance of VariantPicker.



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# File 'lib/fino/ab_testing/variant_picker.rb', line 10

def initialize(setting_definition)
  @setting_definition = setting_definition
end

Instance Attribute Details

#setting_definition ⇒ Object (readonly)

Returns the value of attribute setting_definition.



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# File 'lib/fino/ab_testing/variant_picker.rb', line 8

def setting_definition
  @setting_definition
end

Instance Method Details

#call(variants, scope) ⇒ Object 



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# File 'lib/fino/ab_testing/variant_picker.rb', line 14

def call(variants, scope)
  return nil if variants.empty?

  random = Zlib.crc32("#{setting_definition.key}#{scope}") % (100 * SCALING_FACTOR)
  cumulative = 0

  picked_variant = variants.sort_by(&:percentage).find do |variant|
    cumulative += variant.percentage * SCALING_FACTOR
    random <= cumulative
  end

  Fino.logger.debug { "Variant picked: #{picked_variant}" }

  picked_variant
end