Persist instance statistics object counts

This change will periodically count various objects in the database and
store the data in a database table.

app/models/analytics/instance_statistics/measurement.rb

@@ -12,6 +12,15 @@ module Analytics
         pipelines: 6
       }
 
+      IDENTIFIER_QUERY_MAPPING = {
+        identifiers[:projects] => -> { Project },
+        identifiers[:users] => -> { User },
+        identifiers[:issues] => -> { Issue },
+        identifiers[:merge_requests] => -> { MergeRequest },
+        identifiers[:groups] => -> { Group },
+        identifiers[:pipelines] => -> { Ci::Pipeline }
+      }.freeze
+
       validates :recorded_at, :identifier, :count, presence: true
       validates :recorded_at, uniqueness: { scope: :identifier }
 

app/workers/all_queues.yml

@@ -115,6 +115,14 @@
   :weight: 1
   :idempotent:
   :tags: []
+- :name: cronjob:analytics_instance_statistics_count_job_trigger
+  :feature_category: :instance_statistics
+  :has_external_dependencies:
+  :urgency: :low
+  :resource_boundary: :unknown
+  :weight: 1
+  :idempotent: true
+  :tags: []
 - :name: cronjob:authorized_project_update_periodic_recalculate
   :feature_category: :source_code_management
   :has_external_dependencies:
@@ -1204,6 +1212,14 @@
   :weight: 1
   :idempotent: true
   :tags: []
+- :name: analytics_instance_statistics_counter_job
+  :feature_category: :instance_statistics
+  :has_external_dependencies:
+  :urgency: :low
+  :resource_boundary: :unknown
+  :weight: 1
+  :idempotent: true
+  :tags: []
 - :name: authorized_keys
   :feature_category: :source_code_management
   :has_external_dependencies:

app/workers/analytics/instance_statistics/count_job_trigger_worker.rb

+# frozen_string_literal: true
+
+module Analytics
+  module InstanceStatistics
+    class CountJobTriggerWorker
+      include ApplicationWorker
+      include CronjobQueue # rubocop:disable Scalability/CronWorkerContext
+
+      DEFAULT_DELAY = 3.minutes.freeze
+
+      feature_category :instance_statistics
+      urgency :low
+
+      idempotent!
+
+      def perform
+        return if Feature.disabled?(:store_instance_statistics_measurements)
+
+        recorded_at = Time.zone.now
+        measurement_identifiers = Analytics::InstanceStatistics::Measurement.identifiers
+
+        worker_arguments = Gitlab::Analytics::InstanceStatistics::WorkersArgumentBuilder.new(
+          measurement_identifiers: measurement_identifiers.values,
+          recorded_at: recorded_at
+        ).execute
+
+        perform_in = DEFAULT_DELAY.minutes.from_now
+        worker_arguments.each do |args|
+          CounterJobWorker.perform_in(perform_in, *args)
+
+          perform_in += DEFAULT_DELAY
+        end
+      end
+    end
+  end
+end

app/workers/analytics/instance_statistics/counter_job_worker.rb

+# frozen_string_literal: true
+
+module Analytics
+  module InstanceStatistics
+    class CounterJobWorker
+      include ApplicationWorker
+
+      feature_category :instance_statistics
+      urgency :low
+
+      idempotent!
+
+      def perform(measurement_identifier, min_id, max_id, recorded_at)
+        query_scope = ::Analytics::InstanceStatistics::Measurement::IDENTIFIER_QUERY_MAPPING[measurement_identifier].call
+
+        count = if min_id.nil? || max_id.nil? # table is empty
+                  0
+                else
+                  Gitlab::Database::BatchCount.batch_count(query_scope, start: min_id, finish: max_id)
+                end
+
+        return if count == Gitlab::Database::BatchCounter::FALLBACK
+
+        InstanceStatistics::Measurement.insert_all([{ recorded_at: recorded_at, count: count, identifier: measurement_identifier }])
+      end
+    end
+  end
+end

config/feature_categories.yml

@@ -65,6 +65,7 @@
 - integrations
 - interactive_application_security_testing
 - internationalization
+- instance_statistics
 - issue_tracking
 - jenkins_importer
 - jira_importer

config/feature_flags/development/store_instance_statistics_measurements.yml

+---
+name: store_instance_statistics_measurements
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/41300
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/247871
+group: group::analytics
+type: development
+default_enabled: false

config/initializers/1_settings.rb

@@ -514,6 +514,9 @@ Settings.cron_jobs['postgres_dynamic_partitions_creator']['job_class'] ||= 'Part
 Settings.cron_jobs['ci_platform_metrics_update_cron_worker'] ||= Settingslogic.new({})
 Settings.cron_jobs['ci_platform_metrics_update_cron_worker']['cron'] ||= '47 9 * * *'
 Settings.cron_jobs['ci_platform_metrics_update_cron_worker']['job_class'] = 'CiPlatformMetricsUpdateCronWorker'
+Settings.cron_jobs['analytics_instance_statistics_count_job_trigger_worker'] ||= Settingslogic.new({})
+Settings.cron_jobs['analytics_instance_statistics_count_job_trigger_worker']['cron'] ||= '50 23 */1 * *'
+Settings.cron_jobs['analytics_instance_statistics_count_job_trigger_worker']['job_class'] ||= 'Analytics::InstanceStatistics::CountJobTriggerWorker'
 
 Gitlab.ee do
   Settings.cron_jobs['adjourned_group_deletion_worker'] ||= Settingslogic.new({})

config/sidekiq_queues.yml

@@ -30,6 +30,8 @@
   - 1
 - - analytics_code_review_metrics
   - 1
+- - analytics_instance_statistics_counter_job
+  - 1
 - - authorized_keys
   - 2
 - - authorized_project_update

lib/gitlab/analytics/instance_statistics/workers_argument_builder.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module Analytics
+    module InstanceStatistics
+      class WorkersArgumentBuilder
+        def initialize(measurement_identifiers: [], recorded_at: Time.zone.now)
+          @measurement_identifiers = measurement_identifiers
+          @recorded_at = recorded_at
+        end
+
+        def execute
+          measurement_identifiers.map do |measurement_identifier|
+            query_scope = ::Analytics::InstanceStatistics::Measurement::IDENTIFIER_QUERY_MAPPING[measurement_identifier]&.call
+
+            next if query_scope.nil?
+
+            # Determining the query range (id range) as early as possible in order to get more accurate counts.
+            start = query_scope.minimum(:id)
+            finish = query_scope.maximum(:id)
+
+            [measurement_identifier, start, finish, recorded_at]
+          end.compact
+        end
+
+        private
+
+        attr_reader :measurement_identifiers, :recorded_at
+      end
+    end
+  end
+end

spec/lib/gitlab/analytics/instance_statistics/workers_argument_builder_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::Analytics::InstanceStatistics::WorkersArgumentBuilder do
+  context 'when no measurement identifiers are given' do
+    it 'returns empty array' do
+      expect(described_class.new(measurement_identifiers: []).execute).to be_empty
+    end
+  end
+
+  context 'when measurement identifiers are given' do
+    let_it_be(:user_1) { create(:user) }
+    let_it_be(:project_1) { create(:project, namespace: user_1.namespace, creator: user_1) }
+    let_it_be(:project_2) { create(:project, namespace: user_1.namespace, creator: user_1) }
+    let_it_be(:project_3) { create(:project, namespace: user_1.namespace, creator: user_1) }
+
+    let(:recorded_at) { 2.days.ago }
+    let(:projects_measurement_identifier) { ::Analytics::InstanceStatistics::Measurement.identifiers.fetch(:projects) }
+    let(:users_measurement_identifier) { ::Analytics::InstanceStatistics::Measurement.identifiers.fetch(:users) }
+    let(:measurement_identifiers) { [projects_measurement_identifier, users_measurement_identifier] }
+
+    subject { described_class.new(measurement_identifiers: measurement_identifiers, recorded_at: recorded_at).execute }
+
+    it 'returns worker arguments' do
+      expect(subject).to eq([
+        [projects_measurement_identifier, project_1.id, project_3.id, recorded_at],
+        [users_measurement_identifier, user_1.id, user_1.id, recorded_at]
+      ])
+    end
+
+    context 'when bogus measurement identifiers are given' do
+      before do
+        measurement_identifiers << 'bogus1'
+        measurement_identifiers << 'bogus2'
+      end
+
+      it 'skips bogus measurement identifiers' do
+        expect(subject).to eq([
+          [projects_measurement_identifier, project_1.id, project_3.id, recorded_at],
+          [users_measurement_identifier, user_1.id, user_1.id, recorded_at]
+        ])
+      end
+    end
+  end
+end

spec/workers/analytics/instance_statistics/count_job_trigger_worker_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Analytics::InstanceStatistics::CountJobTriggerWorker do
+  it_behaves_like 'an idempotent worker'
+
+  context 'triggers a job for each measurement identifiers' do
+    let(:expected_count) { Analytics::InstanceStatistics::Measurement.identifiers.size }
+
+    it 'triggers CounterJobWorker jobs' do
+      subject.perform
+
+      expect(Analytics::InstanceStatistics::CounterJobWorker.jobs.count).to eq(expected_count)
+    end
+  end
+
+  context 'when the `store_instance_statistics_measurements` feature flag is off' do
+    before do
+      stub_feature_flags(store_instance_statistics_measurements: false)
+    end
+
+    it 'does not trigger any CounterJobWorker job' do
+      subject.perform
+
+      expect(Analytics::InstanceStatistics::CounterJobWorker.jobs.count).to eq(0)
+    end
+  end
+end

spec/workers/analytics/instance_statistics/counter_job_worker_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Analytics::InstanceStatistics::CounterJobWorker do
+  let_it_be(:user_1) { create(:user) }
+  let_it_be(:user_2) { create(:user) }
+
+  let(:users_measurement_identifier) { ::Analytics::InstanceStatistics::Measurement.identifiers.fetch(:users) }
+  let(:recorded_at) { Time.zone.now }
+  let(:job_args) { [users_measurement_identifier, user_1.id, user_2.id, recorded_at] }
+
+  before do
+    allow(ActiveRecord::Base.connection).to receive(:transaction_open?).and_return(false)
+  end
+
+  include_examples 'an idempotent worker' do
+    it 'counts a scope and stores the result' do
+      subject
+
+      measurement = Analytics::InstanceStatistics::Measurement.first
+      expect(measurement.recorded_at).to be_like_time(recorded_at)
+      expect(measurement.identifier).to eq('users')
+      expect(measurement.count).to eq(2)
+    end
+  end
+
+  context 'when no records are in the database' do
+    let(:users_measurement_identifier) { ::Analytics::InstanceStatistics::Measurement.identifiers.fetch(:groups) }
+
+    subject { described_class.new.perform(users_measurement_identifier, nil, nil, recorded_at) }
+
+    it 'sets 0 as the count' do
+      subject
+
+      measurement = Analytics::InstanceStatistics::Measurement.first
+      expect(measurement.recorded_at).to be_like_time(recorded_at)
+      expect(measurement.identifier).to eq('groups')
+      expect(measurement.count).to eq(0)
+    end
+  end
+
+  it 'does not raise error when inserting duplicated measurement' do
+    subject
+
+    expect { subject }.not_to raise_error
+  end
+
+  it 'does not insert anything when BatchCount returns error' do
+    allow(Gitlab::Database::BatchCount).to receive(:batch_count).and_return(Gitlab::Database::BatchCounter::FALLBACK)
+
+    expect { subject }.not_to change { Analytics::InstanceStatistics::Measurement.count }
+  end
+end