Track linked epics removed on usage ping

Record linked epic removed on usage ping
and use RedisHLL for data aggregation.

Changelog: added
EE: true

ee/app/services/concerns/epics/related_epic_links/usage_data_helper.rb

+# frozen_string_literal: true
+
+module Epics::RelatedEpicLinks::UsageDataHelper
+  ALLOWED_LINK_TYPES =
+    [
+      IssuableLink::TYPE_RELATES_TO,
+      IssuableLink::TYPE_BLOCKS,
+      IssuableLink::TYPE_IS_BLOCKED_BY
+    ].freeze
+
+  ALLOWED_EVENT_TYPES = [:added, :removed].freeze
+
+  def track_related_epics_event_for(link_type:, event_type:)
+    return unless ALLOWED_LINK_TYPES.include?(link_type)
+    return unless ALLOWED_EVENT_TYPES.include?(event_type)
+
+    event_method_name = "track_linked_epic_with_type_#{link_type}_#{event_type}"
+
+    Gitlab::UsageDataCounters::EpicActivityUniqueCounter
+      .method(event_method_name)
+      .call(author: current_user)
+  end
+end

ee/app/services/epics/related_epic_links/create_service.rb

@@ -2,6 +2,8 @@
 
 module Epics::RelatedEpicLinks
   class CreateService < IssuableLinks::CreateService
+    include UsageDataHelper
+
     def linkable_issuables(epics)
       @linkable_issuables ||= begin
         epics.select { |epic| can?(current_user, :admin_epic, epic) }
@@ -15,9 +17,7 @@ module Epics::RelatedEpicLinks
     private
 
     def after_create_for(link)
-      if link.link_type == link.class::TYPE_RELATES_TO
-        ::Gitlab::UsageDataCounters::EpicActivityUniqueCounter.track_epic_related_added(author: current_user)
-      end
+      track_related_epics_event_for(link_type: params[:link_type], event_type: :added)
     end
 
     def references(extractor)

ee/app/services/epics/related_epic_links/destroy_service.rb

@@ -3,6 +3,8 @@
 module Epics
   module RelatedEpicLinks
     class DestroyService < ::IssuableLinks::DestroyService
+      include UsageDataHelper
+
       private
 
       def permission_to_remove_relation?
@@ -10,7 +12,7 @@ module Epics
       end
 
       def track_event
-        # No op
+        track_related_epics_event_for(link_type: link.link_type, event_type: :removed)
       end
 
       def not_found_message

ee/config/metrics/counts_28d/20210318183733_epics_usage_total_unique_counts_monthly.yml

@@ -45,6 +45,7 @@ options:
     - g_project_management_epic_cross_referenced
     - g_project_management_users_epic_issue_added_from_epic
     - g_project_management_epic_related_added
+    - g_project_management_epic_related_removed
 distribution:
 - ee
 tier:

ee/config/metrics/counts_28d/20220323183602_g_project_management_epic_related_removed_monthly.yml

+---
+key_path: redis_hll_counters.epics_usage.g_project_management_epic_related_removed_monthly
+description: Count of MAU removing related epics
+product_section: dev
+product_stage: plan
+product_group: group::product planning
+product_category: epics_usage
+value_type: number
+status: active
+milestone: "14.10"
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/83547
+time_frame: 28d
+data_source: redis_hll
+data_category: optional
+instrumentation_class: RedisHLLMetric
+options:
+  events:
+    - g_project_management_epic_related_removed
+distribution:
+- ee
+tier:
+- ultimate

ee/config/metrics/counts_7d/20210318183220_epics_usage_total_unique_counts_weekly.yml

@@ -45,6 +45,7 @@ options:
     - g_project_management_epic_cross_referenced
     - g_project_management_users_epic_issue_added_from_epic
     - g_project_management_epic_related_added
+    - g_project_management_epic_related_removed
 distribution:
 - ee
 tier:

ee/config/metrics/counts_7d/20220323183227_g_project_management_epic_related_removed_weekly.yml

+---
+key_path: redis_hll_counters.epics_usage.g_project_management_epic_related_removed_weekly
+description: Count of WAU removing related epics
+product_section: dev
+product_stage: plan
+product_group: group::product planning
+product_category: epics_usage
+value_type: number
+status: active
+milestone: "14.10"
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/83547
+time_frame: 7d
+data_source: redis_hll
+data_category: optional
+instrumentation_class: RedisHLLMetric
+options:
+  events:
+    - g_project_management_epic_related_removed
+distribution:
+- ee
+tier:
+- ultimate

ee/lib/gitlab/usage_data_counters/epic_activity_unique_counter.rb

@@ -36,6 +36,7 @@ module Gitlab
       EPIC_TASK_UNCHECKED = 'project_management_users_unchecking_epic_task'
       EPIC_CROSS_REFERENCED = 'g_project_management_epic_cross_referenced'
       EPIC_RELATED_ADDED = 'g_project_management_epic_related_added'
+      EPIC_RELATED_REMOVED = 'g_project_management_epic_related_removed'
 
       class << self
         def track_epic_created_action(author:)
@@ -150,10 +151,23 @@ module Gitlab
           track_unique_action(EPIC_CROSS_REFERENCED, author)
         end
 
-        def track_epic_related_added(author:)
+        def track_linked_epic_with_type_relates_to_added(author:)
           track_unique_action(EPIC_RELATED_ADDED, author)
         end
 
+        def track_linked_epic_with_type_relates_to_removed(author:)
+          track_unique_action(EPIC_RELATED_REMOVED, author)
+        end
+
+        def track_linked_epic_with_type_blocks_added(author:)
+        end
+
+        def track_linked_epic_with_type_blocks_removed(author:)
+        end
+
+        def track_linked_epic_with_type_is_blocked_by_added(author:)
+        end
+
         private
 
         def track_unique_action(action, author)

ee/spec/lib/gitlab/usage_data_counters/epic_activity_unique_counter_spec.rb

@@ -340,7 +340,7 @@ RSpec.describe Gitlab::UsageDataCounters::EpicActivityUniqueCounter, :clean_gitl
 
   context 'for related epic added' do
     def track_action(params)
-      described_class.track_epic_related_added(**params)
+      described_class.track_linked_epic_with_type_relates_to_added(**params)
     end
 
     it_behaves_like 'a daily tracked issuable event' do
@@ -349,4 +349,16 @@ RSpec.describe Gitlab::UsageDataCounters::EpicActivityUniqueCounter, :clean_gitl
 
     it_behaves_like 'does not track when feature flag is disabled', :track_epics_activity
   end
+
+  context 'for related epic removed' do
+    def track_action(params)
+      described_class.track_linked_epic_with_type_relates_to_removed(**params)
+    end
+
+    it_behaves_like 'a daily tracked issuable event' do
+      let(:action) { described_class::EPIC_RELATED_REMOVED }
+    end
+
+    it_behaves_like 'does not track when feature flag is disabled', :track_epics_activity
+  end
 end

ee/spec/services/epics/related_epic_links/create_service_spec.rb

@@ -54,14 +54,14 @@ RSpec.describe Epics::RelatedEpicLinks::CreateService do
     end
 
     context 'event tracking' do
-      context 'for related link type' do
+      context 'for relates_to link type' do
         it 'records event for each link created' do
           params = {
             link_type: IssuableLink::TYPE_RELATES_TO,
             issuable_references: [issuable_a, issuable3].map { |epic| epic.to_reference(issuable.group, full: true) }
           }
 
-          expect(Gitlab::UsageDataCounters::EpicActivityUniqueCounter).to receive(:track_epic_related_added).with(author: user).twice
+          expect(Gitlab::UsageDataCounters::EpicActivityUniqueCounter).to receive(:track_linked_epic_with_type_relates_to_added).with(author: user).twice
 
           described_class.new(issuable, user, params).execute
         end

ee/spec/services/epics/related_epic_links/destroy_service_spec.rb

@@ -15,5 +15,21 @@ RSpec.describe Epics::RelatedEpicLinks::DestroyService do
     subject { described_class.new(issuable_link, user).execute }
 
     it_behaves_like 'a destroyable issuable link'
+
+    context 'event tracking' do
+      before do
+        issuable_link.source.resource_parent.add_reporter(user)
+        issuable_link.target.resource_parent.add_reporter(user)
+      end
+
+      context 'for relates_to link type' do
+        it 'records event for related epic link destroyed' do
+          expect(Gitlab::UsageDataCounters::EpicActivityUniqueCounter)
+            .to receive(:track_linked_epic_with_type_relates_to_removed).with(author: user).once
+
+          subject
+        end
+      end
+    end
   end
 end

lib/gitlab/usage_data_counters/known_events/epic_events.yml

@@ -194,3 +194,9 @@
   redis_slot: project_management
   aggregation: daily
   feature_flag: track_epics_activity
+
+- name: g_project_management_epic_related_removed
+  category: epics_usage
+  redis_slot: project_management
+  aggregation: daily
+  feature_flag: track_epics_activity