Fix avg_cycle_analytics giving an uncaught error

In usage data avg_cycle_analytics giving an uncaught error and kills
the whole usage ping. This MR catches errors as well as revises the
implementation not to time out due to non-indexable

changelogs/unreleased/208788-fix-avg_cycle_analytics-giving-an-uncaught-error.yml

+---
+title: Fix avg_cycle_analytics uncaught error and optimize query
+merge_request: 26381
+author:
+type: fixed

lib/gitlab/cycle_analytics/usage_data.rb

@@ -3,15 +3,32 @@
 module Gitlab
   module CycleAnalytics
     class UsageData
+      include Gitlab::Utils::StrongMemoize
       PROJECTS_LIMIT = 10
 
-      attr_reader :projects, :options
+      attr_reader :options
 
       def initialize
-        @projects = Project.sorted_by_activity.limit(PROJECTS_LIMIT)
         @options = { from: 7.days.ago }
       end
 
+      def projects
+        strong_memoize(:projects) do
+          projects = Project.where.not(last_activity_at: nil).order(last_activity_at: :desc).limit(10) +
+                     Project.where.not(last_repository_updated_at: nil).order(last_repository_updated_at: :desc).limit(10)
+
+          projects = projects.uniq.sort_by do |project|
+            [project.last_activity_at, project.last_repository_updated_at].min
+          end
+
+          if projects.size < 10
+            projects.concat(Project.where(last_activity_at: nil, last_repository_updated_at: nil).limit(10))
+          end
+
+          projects.uniq.first(10)
+        end
+      end
+
       def to_json(*)
         total = 0
 

lib/gitlab/usage_data.rb

@@ -122,6 +122,8 @@ module Gitlab
 
       def cycle_analytics_usage_data
         Gitlab::CycleAnalytics::UsageData.new.to_json
+      rescue ActiveRecord::StatementInvalid
+        { avg_cycle_analytics: {} }
       end
 
       def features_usage_data

spec/lib/gitlab/usage_data_spec.rb

@@ -324,6 +324,24 @@ describe Gitlab::UsageData do
         end
       end
 
+      describe '#cycle_analytics_usage_data' do
+        subject { described_class.cycle_analytics_usage_data }
+
+        it 'works when queries time out in new' do
+          allow(Gitlab::CycleAnalytics::UsageData)
+            .to receive(:new).and_raise(ActiveRecord::StatementInvalid.new(''))
+
+          expect { subject }.not_to raise_error
+        end
+
+        it 'works when queries time out in to_json' do
+          allow_any_instance_of(Gitlab::CycleAnalytics::UsageData)
+            .to receive(:to_json).and_raise(ActiveRecord::StatementInvalid.new(''))
+
+          expect { subject }.not_to raise_error
+        end
+      end
+
       describe '#ingress_modsecurity_usage' do
         subject { described_class.ingress_modsecurity_usage }