Add decision service (#46)

Author: delikat

lib/optimizely.rb

@@ -14,7 +14,7 @@
 #    limitations under the License.
 #
 require_relative 'optimizely/audience'
-require_relative 'optimizely/bucketer'
+require_relative 'optimizely/decision_service'
 require_relative 'optimizely/error_handler'
 require_relative 'optimizely/event_builder'
 require_relative 'optimizely/event_dispatcher'
@@ -28,14 +28,14 @@ module Optimizely
   class Project
 
     # Boolean representing if the instance represents a usable Optimizely Project
-    attr_reader   :is_valid
+    attr_reader :is_valid
 
-    attr_accessor :config
-    attr_accessor :bucketer
-    attr_accessor :event_builder
-    attr_accessor :event_dispatcher
-    attr_accessor :logger
-    attr_accessor :error_handler
+    attr_reader :config
+    attr_reader :decision_service
+    attr_reader :error_handler
+    attr_reader :event_builder
+    attr_reader :event_dispatcher
+    attr_reader :logger
 
     def initialize(datafile, event_dispatcher = nil, logger = nil, error_handler = nil, skip_json_validation = false)
       # Constructor for Projects.
@@ -77,7 +77,7 @@ def initialize(datafile, event_dispatcher = nil, logger = nil, error_handler = n
         return
       end
 
-      @bucketer = Bucketer.new(@config)
+      @decision_service = DecisionService.new(@config)
       @event_builder = EventBuilderV2.new(@config)
     end
 
@@ -135,24 +135,13 @@ def get_variation(experiment_key, user_id, attributes = nil)
         return nil
       end
 
-      unless preconditions_valid?(experiment_key, attributes)
+      unless user_inputs_valid?(attributes)
         @logger.log(Logger::INFO, "Not activating user '#{user_id}.")
         return nil
       end
 
-      variation_id = @bucketer.get_forced_variation_id(experiment_key, user_id)
+      variation_id = @decision_service.get_variation(experiment_key, user_id, attributes)
 
-      unless variation_id.nil?
-        return @config.get_variation_key_from_id(experiment_key, variation_id)
-      end
-
-      unless Audience.user_in_experiment?(@config, experiment_key, attributes)
-        @logger.log(Logger::INFO,
-                    "User '#{user_id}' does not meet the conditions to be in experiment '#{experiment_key}'.")
-        return nil
-      end
-
-      variation_id = @bucketer.bucket(experiment_key, user_id)
       unless variation_id.nil?
         return @config.get_variation_key_from_id(experiment_key, variation_id)
       end
@@ -240,25 +229,6 @@ def get_valid_experiments_for_event(event_key, user_id, attributes)
       valid_experiments
     end
 
-    def preconditions_valid?(experiment_key, attributes = nil, event_tags = nil)
-      # Validates preconditions for bucketing a user.
-      #
-      # experiment_key - String key for an experiment.
-      # user_id - String ID of user.
-      # attributes - Hash of user attributes.
-      #
-      # Returns boolean representing whether all preconditions are valid.
-
-      return false unless user_inputs_valid?(attributes, event_tags)
-
-      unless @config.experiment_running?(experiment_key)
-        @logger.log(Logger::INFO, "Experiment '#{experiment_key}' is not running.")
-        return false
-      end
-
-      true
-    end
-
     def user_inputs_valid?(attributes = nil, event_tags = nil)
       # Helper method to validate user inputs.
       #

lib/optimizely/bucketer.rb

@@ -101,36 +101,6 @@ def bucket(experiment_key, user_id)
       nil
     end
 
-    def get_forced_variation_id(experiment_key, user_id)
-      # Determine if a user is forced into a variation for the given experiment and return the id of that variation.
-      #
-      # experiment_key - Key representing the experiment for which user is to be bucketed.
-      # user_id - ID for the user.
-      #
-      # Returns variation ID in which the user with ID user_id is forced into. Nil if no variation.
-
-      forced_variations = @config.get_forced_variations(experiment_key)
-
-      return nil unless forced_variations
-
-      forced_variation_key = forced_variations[user_id]
-
-      return nil unless forced_variation_key
-
-      forced_variation_id = @config.get_variation_id_from_key(experiment_key, forced_variation_key)
-
-      unless forced_variation_id
-        @config.logger.log(
-          Logger::INFO,
-          "Variation key '#{forced_variation_key}' is not in datafile. Not activating user '#{user_id}'."
-        )
-        return nil
-      end
-
-      @config.logger.log(Logger::INFO, "User '#{user_id}' is forced in variation '#{forced_variation_key}'.")
-      forced_variation_id
-    end
-
     private
 
     def find_bucket(bucket_value, traffic_allocations)

lib/optimizely/decision_service.rb

@@ -0,0 +1,106 @@
+#
+#    Copyright 2017, Optimizely and contributors
+#
+#    Licensed under the Apache License, Version 2.0 (the "License");
+#    you may not use this file except in compliance with the License.
+#    You may obtain a copy of the License at
+#
+#        http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS,
+#    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#    See the License for the specific language governing permissions and
+#    limitations under the License.
+#
+require_relative './bucketer'
+
+module Optimizely
+  class DecisionService
+    # Optimizely's decision service that determines into which variation of an experiment a user will be allocated.
+    #
+    # The decision service contains all logic relating to how a user bucketing decisions is made.
+    # This includes all of the following (in order):
+    #
+    # 1. Checking experiment status
+    # 2. Checking whitelisting
+    # 3. Checking audience targeting
+    # 4. Using Murmurhash3 to bucket the user
+
+    attr_reader :bucketer
+    attr_reader :config
+
+    def initialize(config)
+      @config = config
+      @bucketer = Bucketer.new(@config)
+    end
+
+    def get_variation(experiment_key, user_id, attributes = nil)
+      # Determines variation into which user will be bucketed.
+      #
+      # experiment_key - Experiment for which visitor variation needs to be determined
+      # user_id - String ID for user
+      # attributes - Hash representing user attributes
+      #
+      # Returns variation ID where visitor will be bucketed (nil if experiment is inactive or user does not meet audience conditions)
+
+      # Check to make sure experiment is active
+      unless @config.experiment_running?(experiment_key)
+        @config.logger.log(Logger::INFO, "Experiment '#{experiment_key}' is not running.")
+        return nil
+      end
+
+      # Check if user is in a forced variation
+      variation_id = get_forced_variation_id(experiment_key, user_id)
+
+      if variation_id.nil?
+        unless Audience.user_in_experiment?(@config, experiment_key, attributes)
+          @config.logger.log(
+            Logger::INFO,
+            "User '#{user_id}' does not meet the conditions to be in experiment '#{experiment_key}'."
+          )
+          return nil
+        end
+
+        variation_id = @bucketer.bucket(experiment_key, user_id)
+      end
+
+      variation_id
+    end
+
+    private
+    
+    def get_forced_variation_id(experiment_key, user_id)
+      # Determine if a user is forced into a variation for the given experiment and return the ID of that variation
+      #
+      # experiment_key - Key representing the experiment for which user is to be bucketed
+      # user_id - ID for the user
+      #
+      # Returns variation ID into which user_id is forced (nil if no variation)
+
+      forced_variations = @config.get_forced_variations(experiment_key)
+
+      return nil unless forced_variations
+
+      forced_variation_key = forced_variations[user_id]
+
+      return nil unless forced_variation_key
+
+      forced_variation_id = @config.get_variation_id_from_key(experiment_key, forced_variation_key)
+
+      unless forced_variation_id
+        @config.logger.log(
+          Logger::INFO,
+          "User '#{user_id}' is whitelisted into variation '#{forced_variation_key}', which is not in the datafile."
+        )
+        return nil
+      end
+
+      @config.logger.log(
+        Logger::INFO,
+        "User '#{user_id}' is whitelisted into variation '#{forced_variation_key}' of experiment '#{experiment_key}'."
+      )
+      forced_variation_id
+    end
+  end
+end

lib/optimizely/event_builder.rb

@@ -42,7 +42,7 @@ def ==(event)
 
   class BaseEventBuilder
     attr_reader :config
-    attr_accessor :params
+    attr_reader :params
 
     def initialize(config)
       @config = config

spec/bucketing_spec.rb

@@ -129,32 +129,6 @@ def get_bucketing_id(user_id, entity_id=nil)
                       .with(Logger::DEBUG, "Bucketed into an empty traffic range. Returning nil.")
   end
 
-  describe '#get_forced_variation_id' do
-    it 'should return correct variation ID if user ID is in forcedVariations and variation is valid' do
-      expect(bucketer.get_forced_variation_id('test_experiment', 'forced_user1')).to eq('111128')
-      expect(spy_logger).to have_received(:log)
-                              .once.with(Logger::INFO, "User 'forced_user1' is forced in variation 'control'.")
-
-      expect(bucketer.get_forced_variation_id('test_experiment', 'forced_user2')).to eq('111129')
-      expect(spy_logger).to have_received(:log)
-                              .once.with(Logger::INFO, "User 'forced_user2' is forced in variation 'variation'.")
-    end
-
-    it 'should return null if forced variation ID is not in the datafile' do
-      expect(bucketer.get_forced_variation_id('test_experiment', 'forced_user_with_invalid_variation')).to be_nil
-    end
-
-    it 'should respect forced variations within mutually exclusive grouped experiments' do
-      expect(bucketer).not_to receive(:generate_bucket_value)
-
-      expect(bucketer.get_forced_variation_id('group1_exp2', 'forced_group_user1')).to eq('130004')
-      expect(spy_logger).to have_received(:log)
-                              .once.with(Logger::INFO, "User 'forced_group_user1' is forced in variation 'g1_e2_v2'.")
-    end
-
-
-  end
-
   describe 'logging' do
     it 'should log the results of bucketing a user into variation 1' do
       expect(bucketer).to receive(:generate_bucket_value).and_return(50)