Class: ConfigCat::RolloutEvaluator

Inherits:
Object
  • Object
show all
Defined in:
lib/configcat/rolloutevaluator.rb

Instance Method Summary collapse

Constructor Details

#initialize(log) ⇒ RolloutEvaluator

Returns a new instance of RolloutEvaluator.



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# File 'lib/configcat/rolloutevaluator.rb', line 11

def initialize(log)
  @log = log
end

Instance Method Details

#evaluate(key:, user:, default_value:, default_variation_id:, config:, log_builder:, visited_keys: nil) ⇒ Object

:returns value, variation_id. matched_targeting_rule, matched_percentage_option, error



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# File 'lib/configcat/rolloutevaluator.rb', line 16

def evaluate(key:, user:, default_value:, default_variation_id:, config:, log_builder:, visited_keys: nil)
  visited_keys ||= []
  is_root_flag_evaluation = visited_keys.empty?

  settings = config[FEATURE_FLAGS] || {}
  setting_descriptor = settings[key]

  if setting_descriptor.nil?
    error = "Failed to evaluate setting '#{key}' (the key was not found in config JSON). " \
            "Returning the `default_value` parameter that you specified in your application: '#{default_value}'. " \
            "Available keys: [#{settings.keys.map { |s| "'#{s}'" }.join(", ")}]."
    @log.error(1001, error)
    return default_value, default_variation_id, nil, nil, error
  end

  setting_type = setting_descriptor[SETTING_TYPE]
  salt = setting_descriptor[INLINE_SALT] || ''
  targeting_rules = setting_descriptor[TARGETING_RULES] || []
  percentage_rule_attribute = setting_descriptor[PERCENTAGE_RULE_ATTRIBUTE]

  context = EvaluationContext.new(key, setting_type, user, visited_keys)
  user_has_invalid_type = context.user && !context.user.is_a?(User)
  if user_has_invalid_type
    @log.warn(4001, "Cannot evaluate targeting rules and % options for setting '#{key}' " \
                    "(User Object is not an instance of User type). " \
                    "You should pass a User Object to the evaluation methods like `get_value()` " \
                    "in order to make targeting work properly. " \
                    "Read more: https://configcat.com/docs/advanced/user-object/")
    # We set the user to nil and won't log further missing user object warnings
    context.user = nil
    context.is_missing_user_object_logged = true
  end

  begin
    if log_builder && is_root_flag_evaluation
      log_builder.append("Evaluating '#{key}'")
      log_builder.append(" for User '#{context.user}'") if context.user
      log_builder.increase_indent
    end

    # Evaluate targeting rules (logically connected by OR)
    if log_builder && targeting_rules.any?
      log_builder.new_line("Evaluating targeting rules and applying the first match if any:")
    end
    targeting_rules.each do |targeting_rule|
      conditions = targeting_rule[CONDITIONS] || []

      if conditions.any?
        served_value = targeting_rule[SERVED_VALUE]
        value = Config.get_value(served_value, setting_type) if served_value

        # Evaluate targeting rule conditions (logically connected by AND)
        if evaluate_conditions(conditions, context, salt, config, log_builder, value)
          if served_value
            variation_id = served_value[VARIATION_ID] || default_variation_id
            log_builder.new_line("Returning '#{value}'.") if log_builder && is_root_flag_evaluation
            return [value, variation_id, targeting_rule, nil, nil]
          end
        else
          next
        end
      end

      # Evaluate percentage options of the targeting rule
      log_builder&.increase_indent
      percentage_options = targeting_rule.fetch(TARGETING_RULE_PERCENTAGE_OPTIONS, [])
      percentage_evaluation_result, percentage_value, percentage_variation_id, percentage_option =
        evaluate_percentage_options(percentage_options, context, percentage_rule_attribute,
                                    default_variation_id, log_builder)

      if percentage_evaluation_result
        if log_builder
          log_builder.decrease_indent
          log_builder.new_line("Returning '#{percentage_value}'.") if is_root_flag_evaluation
        end
        return [percentage_value, percentage_variation_id, targeting_rule, percentage_option, nil]
      else
        if log_builder
          log_builder.new_line('The current targeting rule is ignored and the evaluation continues with the next rule.')
          log_builder.decrease_indent
        end
        next
      end
    end

    # Evaluate percentage options
    percentage_options = setting_descriptor.fetch(PERCENTAGE_OPTIONS, [])
    percentage_evaluation_result, percentage_value, percentage_variation_id, percentage_option =
      evaluate_percentage_options(percentage_options, context, percentage_rule_attribute,
                                  default_variation_id, log_builder)

    if percentage_evaluation_result
      log_builder.new_line("Returning '#{percentage_value}'.") if log_builder && is_root_flag_evaluation
      return [percentage_value, percentage_variation_id, nil, percentage_option, nil]
    end

    return_value = Config.get_value(setting_descriptor, setting_type)
    return_variation_id = setting_descriptor.fetch(VARIATION_ID, default_variation_id)
    log_builder.new_line("Returning '#{return_value}'.") if log_builder && is_root_flag_evaluation
    return [return_value, return_variation_id, nil, nil, nil]
  rescue => e
    # During the recursive evaluation of a prerequisite flag, we propagate the exceptions
    # and let the root flag's evaluation code handle them.
    if !is_root_flag_evaluation
      raise e
    else
      error = "Failed to evaluate setting '#{key}'. (#{e}). " \
        "Returning the `%s` parameter that you specified in your application: '#{default_value}'."
      @log.error(2001, error)
      return [default_value, default_variation_id, nil, nil, error]
    end
  end
end