refactor cycle analytics - updated based on MR feedback

13 files changed, 89 insertions, 61 deletions

diff --git a/lib/gitlab/cycle_analytics/base_event.rb b/lib/gitlab/cycle_analytics/base_event.rb
index d540cb6549c..eac807af037 100644
--- a/lib/gitlab/cycle_analytics/base_event.rb
+++ b/lib/gitlab/cycle_analytics/base_event.rb
@@ -2,13 +2,13 @@ module Gitlab
   module CycleAnalytics
     class BaseEvent
       include MetricsTables
+      include ClassNameUtil
 
-      attr_reader :stage, :start_time_attrs, :end_time_attrs, :projections, :query
+      attr_reader :start_time_attrs, :end_time_attrs, :projections, :query
 
-      def initialize(fetcher:, stage:, options:)
+      def initialize(fetcher:, options:)
         @query = EventsQuery.new(fetcher: fetcher)
         @project = fetcher.project
-        @stage = stage
         @options = options
       end
 
@@ -26,6 +26,10 @@ module Gitlab
         @order || @start_time_attrs
       end
 
+      def stage
+        class_name_for('Event')
+      end
+
       private
 
       def update_author!
diff --git a/lib/gitlab/cycle_analytics/base_stage.rb b/lib/gitlab/cycle_analytics/base_stage.rb
index 162ebf18c77..551318f536a 100644
--- a/lib/gitlab/cycle_analytics/base_stage.rb
+++ b/lib/gitlab/cycle_analytics/base_stage.rb
@@ -1,29 +1,36 @@
 module Gitlab
   module CycleAnalytics
     class BaseStage
-      attr_reader :stage, :description
+      include ClassNameUtil
 
-      def initialize(project:, options:, stage:)
+      def initialize(project:, options:)
         @project = project
         @options = options
         @fetcher = Gitlab::CycleAnalytics::MetricsFetcher.new(project: project,
                                                               from: options[:from],
                                                               branch: options[:branch])
-        @stage = stage
       end
 
       def events
-        event_class.new(fetcher: @fetcher, stage: @stage, options: @options).fetch
+        Gitlab::CycleAnalytics::Event[stage].new(fetcher: @fetcher, options: @options).fetch
       end
 
       def median_data
         AnalyticsStageSerializer.new.represent(self).as_json
       end
 
+      def title
+        stage.to_s.capitalize
+      end
+
+      def median
+        raise NotImplementedError.new("Expected #{self.name} to implement median")
+      end
+
       private
 
-      def event_class
-        "Gitlab::CycleAnalytics::#{@stage.to_s.capitalize}Event".constantize
+      def stage
+        class_name_for('Stage')
       end
     end
   end
diff --git a/lib/gitlab/cycle_analytics/class_name_util.rb b/lib/gitlab/cycle_analytics/class_name_util.rb
new file mode 100644
index 00000000000..aac8d888077
--- /dev/null
+++ b/lib/gitlab/cycle_analytics/class_name_util.rb
@@ -0,0 +1,13 @@
+module Gitlab
+  module CycleAnalytics
+    module ClassNameUtil
+      def class_name_for(type)
+        class_name.split(type).first.to_sym
+      end
+
+      def class_name
+        self.class.name.demodulize
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/cycle_analytics/code_stage.rb b/lib/gitlab/cycle_analytics/code_stage.rb
index f72989c9a72..778ce7b5435 100644
--- a/lib/gitlab/cycle_analytics/code_stage.rb
+++ b/lib/gitlab/cycle_analytics/code_stage.rb
@@ -1,16 +1,14 @@
 module Gitlab
   module CycleAnalytics
     class CodeStage < BaseStage
-      def initialize(*args)
-        super(*args)
-
-        @description = "Time until first merge request"
+      def description
+        "Time until first merge request"
       end
 
       def median
-        @fetcher.calculate_metric(:code,
-                                  Issue::Metrics.arel_table[:first_mentioned_in_commit_at],
-                                  MergeRequest.arel_table[:created_at])
+        @fetcher.median(:code,
+                        Issue::Metrics.arel_table[:first_mentioned_in_commit_at],
+                        MergeRequest.arel_table[:created_at])
       end
     end
   end
diff --git a/lib/gitlab/cycle_analytics/event.rb b/lib/gitlab/cycle_analytics/event.rb
new file mode 100644
index 00000000000..62fac89a0d5
--- /dev/null
+++ b/lib/gitlab/cycle_analytics/event.rb
@@ -0,0 +1,9 @@
+module Gitlab
+  module CycleAnalytics
+    module Event
+      def self.[](stage_name)
+        const_get("::Gitlab::CycleAnalytics::#{stage_name.to_s.camelize}Event")
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/cycle_analytics/issue_stage.rb b/lib/gitlab/cycle_analytics/issue_stage.rb
index a2ada238cd2..c317872fb1d 100644
--- a/lib/gitlab/cycle_analytics/issue_stage.rb
+++ b/lib/gitlab/cycle_analytics/issue_stage.rb
@@ -1,17 +1,15 @@
 module Gitlab
   module CycleAnalytics
     class IssueStage < BaseStage
-      def initialize(*args)
-        super(*args)
-
-        @description = "Time before an issue gets scheduled"
+      def description
+        "Time before an issue gets scheduled"
       end
 
       def median
-        @fetcher.calculate_metric(:issue,
-                                  Issue.arel_table[:created_at],
-                                  [Issue::Metrics.arel_table[:first_associated_with_milestone_at],
-                                   Issue::Metrics.arel_table[:first_added_to_board_at]])
+        @fetcher.median(:issue,
+                        Issue.arel_table[:created_at],
+                        [Issue::Metrics.arel_table[:first_associated_with_milestone_at],
+                         Issue::Metrics.arel_table[:first_added_to_board_at]])
       end
     end
   end
diff --git a/lib/gitlab/cycle_analytics/metrics_fetcher.rb b/lib/gitlab/cycle_analytics/metrics_fetcher.rb
index 51835bbde24..bd68a0980ca 100644
--- a/lib/gitlab/cycle_analytics/metrics_fetcher.rb
+++ b/lib/gitlab/cycle_analytics/metrics_fetcher.rb
@@ -15,7 +15,7 @@ module Gitlab
         @branch = branch
       end
 
-      def calculate_metric(name, start_time_attrs, end_time_attrs)
+      def median(name, start_time_attrs, end_time_attrs)
         cte_table = Arel::Table.new("cte_table_for_#{name}")
 
         # Build a `SELECT` query. We find the first of the `end_time_attrs` that isn't `NULL` (call this end_time).
diff --git a/lib/gitlab/cycle_analytics/plan_stage.rb b/lib/gitlab/cycle_analytics/plan_stage.rb
index c836068c4ef..5e6dd30d9e3 100644
--- a/lib/gitlab/cycle_analytics/plan_stage.rb
+++ b/lib/gitlab/cycle_analytics/plan_stage.rb
@@ -1,17 +1,15 @@
 module Gitlab
   module CycleAnalytics
     class PlanStage < BaseStage
-      def initialize(*args)
-        super(*args)
-
-        @description = "Time before an issue starts implementation"
+      def description
+        "Time before an issue starts implementation"
       end
 
       def median
-        @fetcher.calculate_metric(:plan,
-                                  [Issue::Metrics.arel_table[:first_associated_with_milestone_at],
-                                   Issue::Metrics.arel_table[:first_added_to_board_at]],
-                                  Issue::Metrics.arel_table[:first_mentioned_in_commit_at])
+        @fetcher.median(:plan,
+                        [Issue::Metrics.arel_table[:first_associated_with_milestone_at],
+                         Issue::Metrics.arel_table[:first_added_to_board_at]],
+                        Issue::Metrics.arel_table[:first_mentioned_in_commit_at])
       end
     end
   end
diff --git a/lib/gitlab/cycle_analytics/production_stage.rb b/lib/gitlab/cycle_analytics/production_stage.rb
index d46d37e1acc..acd2f7b2b3b 100644
--- a/lib/gitlab/cycle_analytics/production_stage.rb
+++ b/lib/gitlab/cycle_analytics/production_stage.rb
@@ -1,16 +1,14 @@
 module Gitlab
   module CycleAnalytics
     class ProductionStage < BaseStage
-      def initialize(*args)
-        super(*args)
-
-        @description = "From issue creation until deploy to production"
+      def description
+        "From issue creation until deploy to production"
       end
 
       def median
-        @fetcher.calculate_metric(:production,
-                                  Issue.arel_table[:created_at],
-                                  MergeRequest::Metrics.arel_table[:first_deployed_to_production_at])
+        @fetcher.median(:production,
+                        Issue.arel_table[:created_at],
+                        MergeRequest::Metrics.arel_table[:first_deployed_to_production_at])
       end
     end
   end
diff --git a/lib/gitlab/cycle_analytics/review_stage.rb b/lib/gitlab/cycle_analytics/review_stage.rb
index 4159ba5d70d..c7b5e34e16a 100644
--- a/lib/gitlab/cycle_analytics/review_stage.rb
+++ b/lib/gitlab/cycle_analytics/review_stage.rb
@@ -1,16 +1,14 @@
 module Gitlab
   module CycleAnalytics
     class ReviewStage < BaseStage
-      def initialize(*args)
-        super(*args)
-
-        @description = "Time between merge request creation and merge/close"
+      def description
+        "Time between merge request creation and merge/close"
       end
 
       def median
-        @fetcher.calculate_metric(:review,
-                                  MergeRequest.arel_table[:created_at],
-                                  MergeRequest::Metrics.arel_table[:merged_at])
+        @fetcher.median(:review,
+                        MergeRequest.arel_table[:created_at],
+                        MergeRequest::Metrics.arel_table[:merged_at])
       end
     end
   end
diff --git a/lib/gitlab/cycle_analytics/stage.rb b/lib/gitlab/cycle_analytics/stage.rb
new file mode 100644
index 00000000000..acf746db6cd
--- /dev/null
+++ b/lib/gitlab/cycle_analytics/stage.rb
@@ -0,0 +1,9 @@
+module Gitlab
+  module CycleAnalytics
+    module Stage
+      def self.[](stage_name)
+        const_get("::Gitlab::CycleAnalytics::#{stage_name.to_s.camelize}Stage")
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/cycle_analytics/staging_stage.rb b/lib/gitlab/cycle_analytics/staging_stage.rb
index cb4398f15ac..b715a9453c7 100644
--- a/lib/gitlab/cycle_analytics/staging_stage.rb
+++ b/lib/gitlab/cycle_analytics/staging_stage.rb
@@ -1,16 +1,14 @@
 module Gitlab
   module CycleAnalytics
     class StagingStage < BaseStage
-      def initialize(*args)
-        super(*args)
-
-        @description = "From merge request merge until deploy to production"
+      def description
+        "From merge request merge until deploy to production"
       end
 
       def median
-        @fetcher.calculate_metric(:staging,
-                                  MergeRequest::Metrics.arel_table[:merged_at],
-                                  MergeRequest::Metrics.arel_table[:first_deployed_to_production_at])
+        @fetcher.median(:staging,
+                        MergeRequest::Metrics.arel_table[:merged_at],
+                        MergeRequest::Metrics.arel_table[:first_deployed_to_production_at])
       end
     end
   end
diff --git a/lib/gitlab/cycle_analytics/test_stage.rb b/lib/gitlab/cycle_analytics/test_stage.rb
index 3ab93bebd87..58f72bb405e 100644
--- a/lib/gitlab/cycle_analytics/test_stage.rb
+++ b/lib/gitlab/cycle_analytics/test_stage.rb
@@ -1,16 +1,14 @@
 module Gitlab
   module CycleAnalytics
     class TestStage < BaseStage
-      def initialize(*args)
-        super(*args)
-
-        @description = "Total test time for all commits/merges"
+      def description
+        "Total test time for all commits/merges"
       end
 
       def median
-        @fetcher.calculate_metric(:test,
-                                  MergeRequest::Metrics.arel_table[:latest_build_started_at],
-                                  MergeRequest::Metrics.arel_table[:latest_build_finished_at])
+        @fetcher.median(:test,
+                        MergeRequest::Metrics.arel_table[:latest_build_started_at],
+                        MergeRequest::Metrics.arel_table[:latest_build_finished_at])
       end
     end
   end