Track issues removed from epics on usage ping

Track issues removed from epics
on usage ping using Redis HLL.

app/services/issuable_links/destroy_service.rb

@@ -15,14 +15,18 @@ module IssuableLinks
       return error(not_found_message, 404) unless permission_to_remove_relation?
 
       remove_relation
-      create_notes
-      track_event
+      after_destroy
 
       success(message: 'Relation was removed')
     end
 
     private
 
+    def after_destroy
+      create_notes
+      track_event
+    end
+
     def remove_relation
       link.destroy!
     end

doc/development/usage_ping/dictionary.md

@@ -9908,6 +9908,30 @@ Status: `implemented`
 
 Tiers: `premium`, `ultimate`
 
+### `redis_hll_counters.epics_usage.g_project_management_epic_issue_removed_monthly`
+
+Count of MAU removing issues from epics
+
+[YAML definition](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/config/metrics/counts_28d/20210401183230_g_project_management_epic_issue_removed_monthly.yml)
+
+Group: `group::product planning`
+
+Status: `implemented`
+
+Tiers: `premium`, `ultimate`
+
+### `redis_hll_counters.epics_usage.g_project_management_epic_issue_removed_weekly`
+
+Counts of WAU removing issues from epics
+
+[YAML definition](https://gitlab.com/gitlab-org/gitlab/-/blob/master/ee/config/metrics/counts_7d/20210401182457_g_project_management_g_project_management_epic_issue_removed_weekly.yml)
+
+Group: `group::product planning`
+
+Status: `implemented`
+
+Tiers: `premium`, `ultimate`
+
 ### `redis_hll_counters.epics_usage.g_project_management_epic_reopened_monthly`
 
 Counts of MAU closing epics

ee/app/services/epic_issues/destroy_service.rb

@@ -2,14 +2,21 @@
 
 module EpicIssues
   class DestroyService < IssuableLinks::DestroyService
-    def execute
-      result = super
-      Epics::UpdateDatesService.new([link.epic]).execute
+    extend ::Gitlab::Utils::Override
+
+    private
+
+    override :after_destroy
+    def after_destroy
+      super
 
-      result
+      Epics::UpdateDatesService.new([link.epic]).execute
+      track_usage_ping_event
     end
 
-    private
+    def track_usage_ping_event
+      ::Gitlab::UsageDataCounters::EpicActivityUniqueCounter.track_epic_issue_removed(author: current_user)
+    end
 
     def source
       @source ||= link.epic

ee/changelogs/unreleased/issue_292253-issue_removed_from_epic.yml

+---
+title: Track issue removed from epic on usage ping
+merge_request: 58426
+author:
+type: other

ee/config/metrics/counts_28d/20210401183230_g_project_management_epic_issue_removed_monthly.yml

+---
+# Name of this metric contains g_project_management prefix
+# because we are using the same slot from issue_tracking to
+# allow data aggregation.
+key_path: redis_hll_counters.epics_usage.g_project_management_epic_issue_removed_monthly
+description: Count of MAU removing issues from epics
+product_section: dev
+product_stage: plan
+product_group: group::product planning
+product_category: epics_usage
+value_type: number
+status: implemented
+milestone: "13.11"
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/58426
+time_frame: 28d
+data_source: redis_hll
+distribution:
+- ee
+tier:
+- premium
+- ultimate

ee/config/metrics/counts_7d/20210401182457_g_project_management_g_project_management_epic_issue_removed_weekly.yml

+---
+# Name of this metric contains g_project_management prefix
+# because we are using the same slot from issue_tracking to
+# allow data aggregation.
+key_path: redis_hll_counters.epics_usage.g_project_management_epic_issue_removed_weekly
+description: Counts of WAU removing issues from epics
+product_section: dev
+product_stage: plan
+product_group: group::product planning
+product_category: epics_usage
+value_type: number
+status: implemented
+milestone: "13.11"
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/58426
+time_frame: 7d
+data_source: redis_hll
+distribution:
+- ee
+tier:
+- premium
+- ultimate

ee/lib/gitlab/usage_data_counters/epic_activity_unique_counter.rb

@@ -20,6 +20,7 @@ module Gitlab
       EPIC_FIXED_START_DATE_UPDATED = 'g_project_management_users_updating_fixed_epic_start_date'
       EPIC_FIXED_DUE_DATE_UPDATED = 'g_project_management_users_updating_fixed_epic_due_date'
       EPIC_ISSUE_ADDED = 'g_project_management_epic_issue_added'
+      EPIC_ISSUE_REMOVED = 'g_project_management_epic_issue_removed'
       EPIC_CLOSED = 'g_project_management_epic_closed'
       EPIC_REOPENED = 'g_project_management_epic_reopened'
       ISSUE_PROMOTED_TO_EPIC = 'g_project_management_issue_promoted_to_epic'
@@ -77,6 +78,10 @@ module Gitlab
           track_unique_action(EPIC_ISSUE_ADDED, author)
         end
 
+        def track_epic_issue_removed(author:)
+          track_unique_action(EPIC_ISSUE_REMOVED, author)
+        end
+
         def track_epic_closed_action(author:)
           track_unique_action(EPIC_CLOSED, author)
         end

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

@@ -188,6 +188,18 @@ RSpec.describe Gitlab::UsageDataCounters::EpicActivityUniqueCounter, :clean_gitl
     it_behaves_like 'does not track when feature flag is disabled', :track_epics_activity
   end
 
+  context 'for removing issue from epic event' do
+    def track_action(params)
+      described_class.track_epic_issue_removed(**params)
+    end
+
+    it_behaves_like 'a daily tracked issuable event' do
+      let(:action) { described_class::EPIC_ISSUE_REMOVED }
+    end
+
+    it_behaves_like 'does not track when feature flag is disabled', :track_epics_activity
+  end
+
   context 'for promoting issue to epic' do
     def track_action(params)
       described_class.track_issue_promoted_to_epic(**params)

ee/spec/services/epic_issues/destroy_service_spec.rb

@@ -66,6 +66,13 @@ RSpec.describe EpicIssues::DestroyService do
           expect(note.noteable_type).to eq('Issue')
           expect(note.system_note_metadata.action).to eq('issue_removed_from_epic')
         end
+
+        it 'counts an usage ping event' do
+          expect(::Gitlab::UsageDataCounters::EpicActivityUniqueCounter).to receive(:track_epic_issue_removed)
+            .with(author: user)
+
+          subject
+        end
       end
 
       context 'user does not have permissions to remove associations' do
@@ -76,10 +83,18 @@ RSpec.describe EpicIssues::DestroyService do
         it 'returns error message' do
           is_expected.to eq(message: 'No Issue Link found', status: :error, http_status: 404)
         end
+
+        it 'does not counts an usage ping event' do
+          expect(::Gitlab::UsageDataCounters::EpicActivityUniqueCounter).not_to receive(:track_epic_issue_removed)
+
+          subject
+        end
       end
 
       context 'refresh epic dates' do
         it 'calls UpdateDatesService' do
+          group.add_reporter(user)
+
           expect(Epics::UpdateDatesService).to receive(:new).with([epic_issue.epic]).and_call_original
 
           subject

lib/gitlab/usage_data_counters/known_events/epic_events.yml

@@ -87,6 +87,12 @@
   aggregation: daily
   feature_flag: track_epics_activity
 
+- name: g_project_management_epic_issue_removed
+  category: epics_usage
+  redis_slot: project_management
+  aggregation: daily
+  feature_flag: track_epics_activity
+
 - name: g_project_management_epic_closed
   category: epics_usage
   redis_slot: project_management