1 files changed, 16 insertions, 62 deletions

diff --git a/app/experiments/application_experiment.rb b/app/experiments/application_experiment.rb
index 317514d088b..019e74bcd48 100644
--- a/app/experiments/application_experiment.rb
+++ b/app/experiments/application_experiment.rb
@@ -3,19 +3,27 @@
 class ApplicationExperiment < Gitlab::Experiment # rubocop:disable Gitlab/NamespacedClass
   def enabled?
     return false if Feature::Definition.get(feature_flag_name).nil? # there has to be a feature flag yaml file
-    return false unless Gitlab.dev_env_or_com? # we're in an environment that allows experiments
+    return false unless Gitlab.dev_env_or_com? # we have to be in an environment that allows experiments
 
+    # the feature flag has to be rolled out
     Feature.get(feature_flag_name).state != :off # rubocop:disable Gitlab/AvoidFeatureGet
   end
 
-  def publish(_result)
+  def publish(_result = nil)
     track(:assignment) # track that we've assigned a variant for this context
-    Gon.global.push({ experiment: { name => signature } }, true) # push to client
+
+    # push the experiment data to the client
+    begin
+      Gon.push({ experiment: { name => signature } }, true) # push the experiment data to the client
+    rescue NoMethodError
+      # means we're not in the request cycle, and can't add to Gon. Log a warning maybe?
+    end
   end
 
   def track(action, **event_args)
-    return unless should_track? # no events for opted out actors or excluded subjects
+    return unless should_track? # don't track events for excluded contexts
 
+    # track the event, and mix in the experiment signature data
     Gitlab::Tracking.event(name, action.to_s, **event_args.merge(
       context: (event_args[:context] || []) << SnowplowTracker::SelfDescribingJson.new(
         'iglu:com.gitlab/gitlab_experiment/jsonschema/0-3-0', signature
@@ -23,6 +31,10 @@ class ApplicationExperiment < Gitlab::Experiment # rubocop:disable Gitlab/Namesp
     ))
   end
 
+  def exclude!
+    @excluded = true
+  end
+
   def rollout_strategy
     # no-op override in inherited class as desired
   end
@@ -59,62 +71,4 @@ class ApplicationExperiment < Gitlab::Experiment # rubocop:disable Gitlab/Namesp
 
     nil # Returning nil vs. :control is important for not caching and rollouts.
   end
-
-  # Cache is an implementation on top of Gitlab::Redis::SharedState that also
-  # adheres to the ActiveSupport::Cache::Store interface and uses the redis
-  # hash data type.
-  #
-  # Since Gitlab::Experiment can use any type of caching layer, utilizing the
-  # long lived shared state interface here gives us an efficient way to store
-  # context keys and the variant they've been assigned -- while also giving us
-  # a simple way to clean up an experiments data upon resolution.
-  #
-  # The data structure:
-  #   key: experiment.name
-  #   fields: context key => variant name
-  #
-  # The keys are expected to be `experiment_name:context_key`, which is the
-  # default cache key strategy. So running `cache.fetch("foo:bar", "value")`
-  # would create/update a hash with the key of "foo", with a field named
-  # "bar" that has "value" assigned to it.
-  class Cache < ActiveSupport::Cache::Store # rubocop:disable Gitlab/NamespacedClass
-    # Clears the entire cache for a given experiment. Be careful with this
-    # since it would reset all resolved variants for the entire experiment.
-    def clear(key:)
-      key = hkey(key)[0] # extract only the first part of the key
-      pool do |redis|
-        case redis.type(key)
-        when 'hash', 'none' then redis.del(key)
-        else raise ArgumentError, 'invalid call to clear a non-hash cache key'
-        end
-      end
-    end
-
-    private
-
-    def pool
-      raise ArgumentError, 'missing block' unless block_given?
-
-      Gitlab::Redis::SharedState.with { |redis| yield redis }
-    end
-
-    def hkey(key)
-      key.to_s.split(':') # this assumes the default strategy in gitlab-experiment
-    end
-
-    def read_entry(key, **options)
-      value = pool { |redis| redis.hget(*hkey(key)) }
-      value.nil? ? nil : ActiveSupport::Cache::Entry.new(value)
-    end
-
-    def write_entry(key, entry, **options)
-      return false if entry.value.blank? # don't cache any empty values
-
-      pool { |redis| redis.hset(*hkey(key), entry.value) }
-    end
-
-    def delete_entry(key, **options)
-      pool { |redis| redis.hdel(*hkey(key)) }
-    end
-  end
 end