Class: Optimizely::Bucketer

Inherits:
Object
  • Object
show all
Defined in:
lib/optimizely/bucketer.rb

Constant Summary collapse

BUCKETING_ID_TEMPLATE =

Optimizely bucketing algorithm that evenly distributes visitors.

'%{user_id}%{entity_id}'
HASH_SEED = 
1
MAX_HASH_VALUE = 
2**32
MAX_TRAFFIC_VALUE = 
10_000
UNSIGNED_MAX_32_BIT_VALUE = 
0xFFFFFFFF

Instance Method Summary collapse

Constructor Details

#initialize(config) ⇒ Bucketer

Returns a new instance of Bucketer.



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# File 'lib/optimizely/bucketer.rb', line 29

def initialize(config)
  # Bucketer init method to set bucketing seed and project config data.
  #
  # config - ProjectConfig data to be used in making bucketing decisions.

  @bucket_seed = HASH_SEED
  @config = config
end

Instance Method Details

#bucket(experiment_key, user_id) ⇒ Object 



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# File 'lib/optimizely/bucketer.rb', line 38

def bucket(experiment_key, user_id)
  # Determines ID of variation to be shown for a given experiment key and user ID.
  #
  # experiment_key - String Key representing experiment for which visitor is to be bucketed.
  # user_id - String ID for user.
  #
  # Returns String variation ID in which visitor with ID user_id has been placed. Nil if no variation.

  # handle forced variations if applicable
  forced_variations = @config.get_forced_variations(experiment_key)
  forced_variation_key = forced_variations[user_id]
  if forced_variation_key
    forced_variation_id = @config.get_variation_id_from_key(experiment_key, forced_variation_key)
    if forced_variation_id
      @config.logger.log(Logger::INFO, "User '#{user_id}' is forced in variation '#{forced_variation_key}'.")
      return forced_variation_id
    else
      @config.logger.log(
        Logger::INFO,
        "Variation key '#{forced_variation_key}' is not in datafile. Not activating user '#{user_id}'."
      )
      return nil
    end
  end

  # check if experiment is in a group; if so, check if user is bucketed into specified experiment
  experiment_id = @config.get_experiment_id(experiment_key)
  group_id = @config.get_experiment_group_id(experiment_key)
  if group_id
    group = @config.group_key_map.fetch(group_id)
    if Helpers::Group.random_policy?(group)
      bucketing_id = sprintf(BUCKETING_ID_TEMPLATE, user_id: user_id, entity_id: group_id)
      traffic_allocations = group.fetch('trafficAllocation')
      bucket_value = generate_bucket_value(bucketing_id)
      @config.logger.log(Logger::DEBUG, "Assigned experiment bucket #{bucket_value} to user '#{user_id}'.")
      bucketed_experiment_id = find_bucket(bucket_value, traffic_allocations)

      # return if the user is not bucketed into any experiment
      unless bucketed_experiment_id
        @config.logger.log(Logger::INFO, "User '#{user_id}' is in no experiment.")
        return nil
      end

      # return if the user is bucketed into a different experiment than the one specified
      if bucketed_experiment_id != experiment_id
        @config.logger.log(
          Logger::INFO,
          "User '#{user_id}' is not in experiment '#{experiment_key}' of group #{group_id}."
        )
        return nil
      end

      # continue bucketing if the user is bucketed into the experiment specified
      @config.logger.log(
        Logger::INFO,
        "User '#{user_id}' is in experiment '#{experiment_key}' of group #{group_id}."
      )
    end
  end

  bucketing_id = sprintf(BUCKETING_ID_TEMPLATE, user_id: user_id, entity_id: experiment_id)
  bucket_value = generate_bucket_value(bucketing_id)
  @config.logger.log(Logger::DEBUG, "Assigned variation bucket #{bucket_value} to user '#{user_id}'.")
  traffic_allocations = @config.get_traffic_allocation(experiment_key)
  variation_id = find_bucket(bucket_value, traffic_allocations)
  if variation_id && variation_id != ''
    variation_key = @config.get_variation_key_from_id(experiment_key, variation_id)
    @config.logger.log(
      Logger::INFO,
      "User '#{user_id}' is in variation '#{variation_key}' of experiment '#{experiment_key}'."
    )
    return variation_id
  end

  # Handle the case when the traffic range is empty due to sticky bucketing
  if variation_id == ''
    @config.logger.log(Logger::DEBUG, 'Bucketed into an empty traffic range. Returning nil.')
  end

  @config.logger.log(Logger::INFO, "User '#{user_id}' is in no variation.")
  nil
end