Class: Split::Experiment

Inherits:
Object
  • Object
show all
Defined in:
lib/split/experiment.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name, *alternative_names) ⇒ Experiment

Returns a new instance of Experiment.



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# File 'lib/split/experiment.rb', line 6

def initialize(name, *alternative_names)
  @name = name.to_s
  @alternatives = alternative_names.map do |alternative|
                    Split::Alternative.new(alternative, name)
                  end
end

Instance Attribute Details

#name ⇒ Object

Returns the value of attribute name.



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# File 'lib/split/experiment.rb', line 3

def name
  @name
end

#winner ⇒ Object

Returns the value of attribute winner.



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# File 'lib/split/experiment.rb', line 4

def winner
  @winner
end

Class Method Details

.all ⇒ Object 



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# File 'lib/split/experiment.rb', line 116

def self.all
  Array(Split.redis.smembers(:experiments)).map {|e| find(e)}
end

.find(name) ⇒ Object 



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# File 'lib/split/experiment.rb', line 120

def self.find(name)
  if Split.redis.exists(name)
    self.new(name, *load_alternatives_for(name))
  end
end

.find_or_create(key, *alternatives) ⇒ Object 



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# File 'lib/split/experiment.rb', line 126

def self.find_or_create(key, *alternatives)
  name = key.to_s.split(':')[0]

  if alternatives.length == 1
    if alternatives[0].is_a? Hash
      alternatives = alternatives[0].map{|k,v| {k => v} }
    else
      raise InvalidArgument, 'You must declare at least 2 alternatives'
    end
  end

  alts = initialize_alternatives(alternatives, name)

  if Split.redis.exists(name)
    if load_alternatives_for(name) == alts.map(&:name)
      experiment = self.new(name, *alternatives)
    else
      exp = self.new(name, *load_alternatives_for(name))
      exp.reset
      exp.alternatives.each(&:delete)
      experiment = self.new(name, *alternatives)
      experiment.save
    end
  else
    experiment = self.new(name, *alternatives)
    experiment.save
  end
  return experiment

end

.initialize_alternatives(alternatives, name) ⇒ Object 



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# File 'lib/split/experiment.rb', line 157

def self.initialize_alternatives(alternatives, name)

  unless alternatives.all? { |a| Split::Alternative.valid?(a) }
    raise InvalidArgument, 'Alternatives must be strings'
  end

  alternatives.map do |alternative|
    Split::Alternative.new(alternative, name)
  end
end

.load_alternatives_for(name) ⇒ Object 



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# File 'lib/split/experiment.rb', line 104

def self.load_alternatives_for(name)
  case Split.redis.type(name)
  when 'set' # convert legacy sets to lists
    alts = Split.redis.smembers(name)
    Split.redis.del(name)
    alts.reverse.each {|a| Split.redis.lpush(name, a) }
    Split.redis.lrange(name, 0, -1)
  else
    Split.redis.lrange(name, 0, -1)
  end
end

Instance Method Details

#alternative_names ⇒ Object 



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# File 'lib/split/experiment.rb', line 42

def alternative_names
  @alternatives.map(&:name)
end

#alternatives ⇒ Object 



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# File 'lib/split/experiment.rb', line 38

def alternatives
  @alternatives.dup
end

#control ⇒ Object 



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# File 'lib/split/experiment.rb', line 21

def control
  alternatives.first
end

#delete ⇒ Object 



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# File 'lib/split/experiment.rb', line 84

def delete
  alternatives.each(&:delete)
  reset_winner
  Split.redis.srem(:experiments, name)
  Split.redis.del(name)
  increment_version
end

#increment_version ⇒ Object 



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# File 'lib/split/experiment.rb', line 66

def increment_version
  @version = Split.redis.incr("#{name}:version")
end

#key ⇒ Object 



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# File 'lib/split/experiment.rb', line 70

def key
  if version.to_i > 0
    "#{name}:#{version}"
  else
    name
  end
end

#new_record? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/split/experiment.rb', line 92

def new_record?
  !Split.redis.exists(name)
end

#next_alternative ⇒ Object 



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# File 'lib/split/experiment.rb', line 46

def next_alternative
  winner || random_alternative
end

#random_alternative ⇒ Object 



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# File 'lib/split/experiment.rb', line 50

def random_alternative
  weights = alternatives.map(&:weight)

  total = weights.inject(:+)
  point = rand * total

  alternatives.zip(weights).each do |n,w|
    return n if w >= point
    point -= w
  end
end

#reset ⇒ Object 



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# File 'lib/split/experiment.rb', line 78

def reset
  alternatives.each(&:reset)
  reset_winner
  increment_version
end

#reset_winner ⇒ Object 



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# File 'lib/split/experiment.rb', line 25

def reset_winner
  Split.redis.hdel(:experiment_winner, name)
end

#save ⇒ Object 



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# File 'lib/split/experiment.rb', line 96

def save
  if new_record?
    Split.redis.sadd(:experiments, name)
    Split.redis.hset(:experiment_start_times, @name, Time.now)
    @alternatives.reverse.each {|a| Split.redis.lpush(name, a.name) }
  end
end

#start_time ⇒ Object 



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# File 'lib/split/experiment.rb', line 33

def start_time
  t = Split.redis.hget(:experiment_start_times, @name)
  Time.parse(t) if t
end

#version ⇒ Object 



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# File 'lib/split/experiment.rb', line 62

def version
  @version ||= (Split.redis.get("#{name.to_s}:version").to_i || 0)
end