Add redis_hll_tracking ops feature flag

  - Add a global feature for tracking using Redis HLL
  and for adding the Redis data in Usage Ping
  - Add this feature to protect in case of performance
  issues as feature flags specifc per event are removed

config/feature_flags/ops/redis_hll_tracking.yml

+---
+name: redis_hll_tracking
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/56970
+rollout_issue_url:
+milestone: '13.11'
+type: ops
+group: group::product intelligence
+default_enabled: true

lib/gitlab/usage_data.rb

@@ -711,6 +711,8 @@ module Gitlab
       end
 
       def redis_hll_counters
+        return {} unless Feature.enabled?(:redis_hll_tracking, type: :ops, default_enabled: :yaml)
+
         { redis_hll_counters: ::Gitlab::UsageDataCounters::HLLRedisCounter.unique_events_data }
       end
 

lib/gitlab/usage_data_counters/hll_redis_counter.rb

@@ -157,7 +157,7 @@ module Gitlab
         def feature_enabled?(event)
           return true if event[:feature_flag].blank?
 
-          Feature.enabled?(event[:feature_flag], default_enabled: :yaml)
+          Feature.enabled?(event[:feature_flag], default_enabled: :yaml) && Feature.enabled?(:redis_hll_tracking, type: :ops, default_enabled: :yaml)
         end
 
         # Allow to add totals for events that are in the same redis slot, category and have the same aggregation level

spec/lib/gitlab/usage_data_counters/hll_redis_counter_spec.rb

@@ -93,7 +93,25 @@ RSpec.describe Gitlab::UsageDataCounters::HLLRedisCounter, :clean_gitlab_redis_s
     end
 
     describe '.track_event' do
-      context 'with feature flag set' do
+      context 'with redis_hll_tracking' do
+        it 'tracks the event when feature enabled' do
+          stub_feature_flags(redis_hll_tracking: true)
+
+          expect(Gitlab::Redis::HLL).to receive(:add)
+
+          described_class.track_event(weekly_event, values: 1)
+        end
+
+        it 'does not track the event with feature flag disabled' do
+          stub_feature_flags(redis_hll_tracking: false)
+
+          expect(Gitlab::Redis::HLL).not_to receive(:add)
+
+          described_class.track_event(weekly_event, values: 1)
+        end
+      end
+
+      context 'with event feature flag set' do
         it 'tracks the event when feature enabled' do
           stub_feature_flags(feature => true)
 
@@ -111,7 +129,7 @@ RSpec.describe Gitlab::UsageDataCounters::HLLRedisCounter, :clean_gitlab_redis_s
         end
       end
 
-      context 'with no feature flag set' do
+      context 'with no event feature flag set' do
         it 'tracks the event' do
           expect(Gitlab::Redis::HLL).to receive(:add)
 

spec/lib/gitlab/usage_data_spec.rb

@@ -1361,7 +1361,10 @@ RSpec.describe Gitlab::UsageData, :aggregate_failures do
       %w[source_code ci_secrets_management incident_management_alerts snippets terraform]
     end
 
+    context 'with redis_hll_tracking feature enabled' do
       it 'has all known_events' do
+        stub_feature_flags(redis_hll_tracking: true)
+
         expect(subject).to have_key(:redis_hll_counters)
 
         expect(subject[:redis_hll_counters].keys).to match_array(categories)
@@ -1380,6 +1383,15 @@ RSpec.describe Gitlab::UsageData, :aggregate_failures do
       end
     end
 
+    context 'with redis_hll_tracking disabled' do
+      it 'does not have redis_hll_tracking key' do
+        stub_feature_flags(redis_hll_tracking: false)
+
+        expect(subject).not_to have_key(:redis_hll_counters)
+      end
+    end
+  end
+
   describe '.aggregated_metrics_data' do
     it 'uses ::Gitlab::Usage::Metrics::Aggregates::Aggregate methods', :aggregate_failures do
       expected_payload = {