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require 'unleash/activation_strategy'
require 'unleash/constraint'
require 'unleash/variant_definition'
require 'unleash/variant'
require 'unleash/strategy/util'
require 'securerandom'
module Unleash
class FeatureToggle
attr_accessor :name, :enabled, :strategies, :variant_definitions
def initialize(params = {})
params = {} if params.nil?
self.name = params.fetch('name', nil)
self.enabled = params.fetch('enabled', false)
self.strategies = initialize_strategies(params)
self.variant_definitions = initialize_variant_definitions(params)
end
def to_s
"<FeatureToggle: name=#{name},enabled=#{enabled},strategies=#{strategies},variant_definitions=#{variant_definitions}>"
end
def is_enabled?(context, default_result)
result = am_enabled?(context, default_result)
choice = result ? :yes : :no
Unleash.toggle_metrics.increment(name, choice) unless Unleash.configuration.disable_metrics
result
end
def get_variant(context, fallback_variant = disabled_variant)
raise ArgumentError, "Provided fallback_variant is not of type Unleash::Variant" if fallback_variant.class.name != 'Unleash::Variant'
context = ensure_valid_context(context)
return disabled_variant unless self.enabled && am_enabled?(context, true)
return disabled_variant if sum_variant_defs_weights <= 0
variant = variant_from_override_match(context)
variant = variant_from_weights(context) if variant.nil?
Unleash.toggle_metrics.increment_variant(self.name, variant.name) unless Unleash.configuration.disable_metrics
variant
end
private
# only check if it is enabled, do not do metrics
def am_enabled?(context, default_result)
result =
if self.enabled
self.strategies.empty? ||
self.strategies.any? do |s|
strategy_enabled?(s, context) && strategy_constraint_matches?(s, context)
end
else
default_result
end
Unleash.logger.debug "Unleash::FeatureToggle (enabled:#{self.enabled} default_result:#{default_result} " \
"and Strategies combined with contraints returned #{result})"
result
end
def strategy_enabled?(strategy, context)
r = Unleash::STRATEGIES.fetch(strategy.name.to_sym, :unknown).is_enabled?(strategy.params, context)
Unleash.logger.debug "Unleash::FeatureToggle.strategy_enabled? Strategy #{strategy.name} returned #{r} with context: #{context}"
r
end
def strategy_constraint_matches?(strategy, context)
strategy.constraints.empty? || strategy.constraints.all?{ |c| c.matches_context?(context) }
end
def disabled_variant
Unleash::Variant.new(name: 'disabled', enabled: false)
end
def sum_variant_defs_weights
self.variant_definitions.map(&:weight).reduce(0, :+)
end
def variant_salt(context)
return context.user_id unless context.user_id.to_s.empty?
return context.session_id unless context.session_id.to_s.empty?
return context.remote_address unless context.remote_address.to_s.empty?
SecureRandom.random_number
end
def variant_from_override_match(context)
variant = self.variant_definitions.find{ |vd| vd.override_matches_context?(context) }
return nil if variant.nil?
Unleash::Variant.new(name: variant.name, enabled: true, payload: variant.payload)
end
def variant_from_weights(context)
variant_weight = Unleash::Strategy::Util.get_normalized_number(variant_salt(context), self.name, sum_variant_defs_weights)
prev_weights = 0
variant_definition = self.variant_definitions
.find do |v|
res = (prev_weights + v.weight >= variant_weight)
prev_weights += v.weight
res
end
return disabled_variant if variant_definition.nil?
Unleash::Variant.new(name: variant_definition.name, enabled: true, payload: variant_definition.payload)
end
def ensure_valid_context(context)
unless ['NilClass', 'Unleash::Context'].include? context.class.name
Unleash.logger.error "Provided context is not of the correct type #{context.class.name}, " \
"please use Unleash::Context. Context set to nil."
context = nil
end
context
end
def initialize_strategies(params)
params.fetch('strategies', [])
.select{ |s| s.has_key?('name') && Unleash::STRATEGIES.has_key?(s['name'].to_sym) }
.map do |s|
ActivationStrategy.new(
s['name'],
s['parameters'],
(s['constraints'] || []).map do |c|
Constraint.new(
c.fetch('contextName'),
c.fetch('operator'),
c.fetch('values')
)
end
)
end || []
end
def initialize_variant_definitions(params)
(params.fetch('variants', []) || [])
.select{ |v| v.is_a?(Hash) && v.has_key?('name') }
.map do |v|
VariantDefinition.new(
v.fetch('name', ''),
v.fetch('weight', 0),
v.fetch('payload', nil),
v.fetch('overrides', [])
)
end || []
end
end
end
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