module LaunchDarkly::Impl::EvaluatorBucketing
Encapsulates the logic for percentage rollouts.
Public Class Methods
bucket_user(user, key, bucket_by, salt, seed)
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Returns a user's bucket value as a floating-point value in `[0, 1)`.
@param user [Object] the user properties @param key [String] the feature flag key (or segment key, if this is for a segment rule) @param bucket_by [String|Symbol] the name of the user attribute to be used for bucketing @param salt [String] the feature flag's or segment's salt value @return [Number] the bucket value, from 0 inclusive to 1 exclusive
# File lib/ldclient-rb/impl/evaluator_bucketing.rb, line 56 def self.bucket_user(user, key, bucket_by, salt, seed) return nil unless user[:key] id_hash = bucketable_string_value(EvaluatorOperators.user_value(user, bucket_by)) if id_hash.nil? return 0.0 end if user[:secondary] id_hash += "." + user[:secondary].to_s end if seed hash_key = "%d.%s" % [seed, id_hash] else hash_key = "%s.%s.%s" % [key, salt, id_hash] end hash_val = (Digest::SHA1.hexdigest(hash_key))[0..14] hash_val.to_i(16) / Float(0xFFFFFFFFFFFFFFF) end
variation_index_for_user(flag, rule, user)
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Applies either a fixed variation or a rollout for a rule (or the fallthrough rule).
@param flag [Object] the feature flag @param rule [Object] the rule @param user [Object] the user properties @return [Number] the variation index, or nil if there is an error
# File lib/ldclient-rb/impl/evaluator_bucketing.rb, line 12 def self.variation_index_for_user(flag, rule, user) variation = rule[:variation] return variation, false if !variation.nil? # fixed variation rollout = rule[:rollout] return nil, false if rollout.nil? variations = rollout[:variations] if !variations.nil? && variations.length > 0 # percentage rollout bucket_by = rollout[:bucketBy].nil? ? "key" : rollout[:bucketBy] seed = rollout[:seed] bucket = bucket_user(user, flag[:key], bucket_by, flag[:salt], seed) # may not be present sum = 0; variations.each do |variate| if rollout[:kind] == "experiment" && !variate[:untracked] in_experiment = true end sum += variate[:weight].to_f / 100000.0 if bucket < sum return variate[:variation], !!in_experiment end end # The user's bucket value was greater than or equal to the end of the last bucket. This could happen due # to a rounding error, or due to the fact that we are scaling to 100000 rather than 99999, or the flag # data could contain buckets that don't actually add up to 100000. Rather than returning an error in # this case (or changing the scaling, which would potentially change the results for *all* users), we # will simply put the user in the last bucket. last_variation = variations[-1] in_experiment = rollout[:kind] == "experiment" && !last_variation[:untracked] [last_variation[:variation], in_experiment] else # the rule isn't well-formed [nil, false] end end
Private Class Methods
bucketable_string_value(value)
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# File lib/ldclient-rb/impl/evaluator_bucketing.rb, line 80 def self.bucketable_string_value(value) return value if value.is_a? String return value.to_s if value.is_a? Integer nil end