Store hashcode for VSA stage events

Store hashcode for VSA stage events in the newly created
analytics_cycle_analytics_stage_event_hashes database table.

Changelog: added

app/models/analytics/cycle_analytics/stage_event_hash.rb

+# frozen_string_literal: true
+
+module Analytics
+  module CycleAnalytics
+    class StageEventHash < ApplicationRecord
+      has_many :cycle_analytics_project_stages, class_name: 'Analytics::CycleAnalytics::ProjectStage', inverse_of: :stage_event_hash
+
+      validates :hash_sha256, presence: true
+
+      # Creates or queries the id of the corresponding stage event hash code
+      def self.record_id_by_hash_sha256(hash)
+        casted_hash_code = Arel::Nodes.build_quoted(hash, Analytics::CycleAnalytics::StageEventHash.arel_table[:hash_sha256]).to_sql
+
+        # Atomic, safe insert without retrying
+        query = <<~SQL
+        WITH insert_cte AS #{Gitlab::Database::AsWithMaterialized.materialized_if_supported} (
+          INSERT INTO #{quoted_table_name} (hash_sha256) VALUES (#{casted_hash_code}) ON CONFLICT DO NOTHING RETURNING ID
+        )
+        SELECT ids.id FROM (
+          (SELECT id FROM #{quoted_table_name} WHERE hash_sha256=#{casted_hash_code} LIMIT 1)
+            UNION ALL
+          (SELECT id FROM insert_cte LIMIT 1)
+        ) AS ids LIMIT 1
+        SQL
+
+        connection.execute(query).first['id']
+      end
+
+      def self.cleanup_if_unused(id)
+        unused_hashes_for(id)
+          .where(id: id)
+          .delete_all
+      end
+
+      def self.unused_hashes_for(id)
+        exists_query = Analytics::CycleAnalytics::ProjectStage.where(stage_event_hash_id: id).select('1').limit(1)
+        where.not('EXISTS (?)', exists_query)
+      end
+    end
+  end
+end
+Analytics::CycleAnalytics::StageEventHash.prepend_mod_with('Analytics::CycleAnalytics::StageEventHash')

app/models/concerns/analytics/cycle_analytics/stage.rb

@@ -10,6 +10,7 @@ module Analytics
       included do
         belongs_to :start_event_label, class_name: 'GroupLabel', optional: true
         belongs_to :end_event_label, class_name: 'GroupLabel', optional: true
+        belongs_to :stage_event_hash, class_name: 'Analytics::CycleAnalytics::StageEventHash', foreign_key: :stage_event_hash_id, optional: true
 
         validates :name, presence: true
         validates :name, exclusion: { in: Gitlab::Analytics::CycleAnalytics::DefaultStages.names }, if: :custom?
@@ -28,6 +29,9 @@ module Analytics
         scope :ordered, -> { order(:relative_position, :id) }
         scope :for_list, -> { includes(:start_event_label, :end_event_label).ordered }
         scope :by_value_stream, -> (value_stream) { where(value_stream_id: value_stream.id) }
+
+        before_save :ensure_stage_event_hash_id
+        after_commit :cleanup_old_stage_event_hash
       end
 
       def parent=(_)
@@ -133,6 +137,20 @@ module Analytics
           .id_in(label_id)
           .exists?
       end
+
+      def ensure_stage_event_hash_id
+        previous_stage_event_hash = stage_event_hash&.hash_sha256
+
+        if previous_stage_event_hash.blank? || events_hash_code != previous_stage_event_hash
+          self.stage_event_hash_id = Analytics::CycleAnalytics::StageEventHash.record_id_by_hash_sha256(events_hash_code)
+        end
+      end
+
+      def cleanup_old_stage_event_hash
+        if stage_event_hash_id_previously_changed? && stage_event_hash_id_previously_was
+          Analytics::CycleAnalytics::StageEventHash.cleanup_if_unused(stage_event_hash_id_previously_was)
+        end
+      end
     end
   end
 end

db/migrate/20210730101609_create_analytics_cycle_analytics_stage_event_hashes.rb

+# frozen_string_literal: true
+
+class CreateAnalyticsCycleAnalyticsStageEventHashes < ActiveRecord::Migration[6.1]
+  def change
+    create_table :analytics_cycle_analytics_stage_event_hashes do |t|
+      t.binary :hash_sha256
+      t.index :hash_sha256, unique: true, name: 'index_cycle_analytics_stage_event_hashes_on_hash_sha_256'
+    end
+  end
+end

db/migrate/20210730102952_add_stage_hash_fk_to_project_stages.rb

+# frozen_string_literal: true
+
+class AddStageHashFkToProjectStages < ActiveRecord::Migration[6.1]
+  include Gitlab::Database::MigrationHelpers
+
+  disable_ddl_transaction!
+
+  def up
+    unless column_exists?(:analytics_cycle_analytics_project_stages, :stage_event_hash_id)
+      add_column :analytics_cycle_analytics_project_stages, :stage_event_hash_id, :bigint
+    end
+
+    add_concurrent_index :analytics_cycle_analytics_project_stages, :stage_event_hash_id, name: 'index_project_stages_on_stage_event_hash_id'
+    add_concurrent_foreign_key :analytics_cycle_analytics_project_stages, :analytics_cycle_analytics_stage_event_hashes, column: :stage_event_hash_id, on_delete: :cascade
+  end
+
+  def down
+    remove_column :analytics_cycle_analytics_project_stages, :stage_event_hash_id
+  end
+end

db/migrate/20210730103808_add_stage_hash_fk_to_group_stages.rb

+# frozen_string_literal: true
+
+class AddStageHashFkToGroupStages < ActiveRecord::Migration[6.1]
+  include Gitlab::Database::MigrationHelpers
+
+  disable_ddl_transaction!
+
+  def up
+    unless column_exists?(:analytics_cycle_analytics_group_stages, :stage_event_hash_id)
+      add_column :analytics_cycle_analytics_group_stages, :stage_event_hash_id, :bigint
+    end
+
+    add_concurrent_index :analytics_cycle_analytics_group_stages, :stage_event_hash_id, name: 'index_group_stages_on_stage_event_hash_id'
+    add_concurrent_foreign_key :analytics_cycle_analytics_group_stages, :analytics_cycle_analytics_stage_event_hashes, column: :stage_event_hash_id, on_delete: :cascade
+  end
+
+  def down
+    remove_column :analytics_cycle_analytics_group_stages, :stage_event_hash_id
+  end
+end

db/schema_migrations/20210730101609

+f819eaed7e387f18f066180cbf9d0849b3e38db95bbf3e8487d3bc58d9b489ae
\ No newline at end of file

db/schema_migrations/20210730102952

+cb97b869bfb0b76dd0684aca1f40c86e7c1c9c9a0d52684830115288088e8066
\ No newline at end of file

db/schema_migrations/20210730103808

+5c104ffdb64943aa4828a9b961c8f9141dfd2ae861cea7116722d2b0d4598957
\ No newline at end of file

db/structure.sql

@@ -9085,7 +9085,8 @@ CREATE TABLE analytics_cycle_analytics_group_stages (
     hidden boolean DEFAULT false NOT NULL,
     custom boolean DEFAULT true NOT NULL,
     name character varying(255) NOT NULL,
-    group_value_stream_id bigint NOT NULL
+    group_value_stream_id bigint NOT NULL,
+    stage_event_hash_id bigint
 );
 
 CREATE SEQUENCE analytics_cycle_analytics_group_stages_id_seq
@@ -9128,7 +9129,8 @@ CREATE TABLE analytics_cycle_analytics_project_stages (
     hidden boolean DEFAULT false NOT NULL,
     custom boolean DEFAULT true NOT NULL,
     name character varying(255) NOT NULL,
-    project_value_stream_id bigint NOT NULL
+    project_value_stream_id bigint NOT NULL,
+    stage_event_hash_id bigint
 );
 
 CREATE SEQUENCE analytics_cycle_analytics_project_stages_id_seq
@@ -9158,6 +9160,20 @@ CREATE SEQUENCE analytics_cycle_analytics_project_value_streams_id_seq
 
 ALTER SEQUENCE analytics_cycle_analytics_project_value_streams_id_seq OWNED BY analytics_cycle_analytics_project_value_streams.id;
 
+CREATE TABLE analytics_cycle_analytics_stage_event_hashes (
+    id bigint NOT NULL,
+    hash_sha256 bytea
+);
+
+CREATE SEQUENCE analytics_cycle_analytics_stage_event_hashes_id_seq
+    START WITH 1
+    INCREMENT BY 1
+    NO MINVALUE
+    NO MAXVALUE
+    CACHE 1;
+
+ALTER SEQUENCE analytics_cycle_analytics_stage_event_hashes_id_seq OWNED BY analytics_cycle_analytics_stage_event_hashes.id;
+
 CREATE TABLE analytics_devops_adoption_segments (
     id bigint NOT NULL,
     last_recorded_at timestamp with time zone,
@@ -19925,6 +19941,8 @@ ALTER TABLE ONLY analytics_cycle_analytics_project_stages ALTER COLUMN id SET DE
 
 ALTER TABLE ONLY analytics_cycle_analytics_project_value_streams ALTER COLUMN id SET DEFAULT nextval('analytics_cycle_analytics_project_value_streams_id_seq'::regclass);
 
+ALTER TABLE ONLY analytics_cycle_analytics_stage_event_hashes ALTER COLUMN id SET DEFAULT nextval('analytics_cycle_analytics_stage_event_hashes_id_seq'::regclass);
+
 ALTER TABLE ONLY analytics_devops_adoption_segments ALTER COLUMN id SET DEFAULT nextval('analytics_devops_adoption_segments_id_seq'::regclass);
 
 ALTER TABLE ONLY analytics_devops_adoption_snapshots ALTER COLUMN id SET DEFAULT nextval('analytics_devops_adoption_snapshots_id_seq'::regclass);
@@ -21044,6 +21062,9 @@ ALTER TABLE ONLY analytics_cycle_analytics_project_stages
 ALTER TABLE ONLY analytics_cycle_analytics_project_value_streams
     ADD CONSTRAINT analytics_cycle_analytics_project_value_streams_pkey PRIMARY KEY (id);
 
+ALTER TABLE ONLY analytics_cycle_analytics_stage_event_hashes
+    ADD CONSTRAINT analytics_cycle_analytics_stage_event_hashes_pkey PRIMARY KEY (id);
+
 ALTER TABLE ONLY analytics_devops_adoption_segments
     ADD CONSTRAINT analytics_devops_adoption_segments_pkey PRIMARY KEY (id);
 
@@ -23536,6 +23557,8 @@ CREATE INDEX index_custom_emoji_on_creator_id ON custom_emoji USING btree (creat
 
 CREATE UNIQUE INDEX index_custom_emoji_on_namespace_id_and_name ON custom_emoji USING btree (namespace_id, name);
 
+CREATE UNIQUE INDEX index_cycle_analytics_stage_event_hashes_on_hash_sha_256 ON analytics_cycle_analytics_stage_event_hashes USING btree (hash_sha256);
+
 CREATE UNIQUE INDEX index_daily_build_group_report_results_unique_columns ON ci_daily_build_group_report_results USING btree (project_id, ref_path, date, group_name);
 
 CREATE INDEX index_dast_profile_schedules_active_next_run_at ON dast_profile_schedules USING btree (active, next_run_at);
@@ -23960,6 +23983,8 @@ CREATE INDEX index_group_repository_storage_moves_on_group_id ON group_repositor
 
 CREATE UNIQUE INDEX index_group_stages_on_group_id_group_value_stream_id_and_name ON analytics_cycle_analytics_group_stages USING btree (group_id, group_value_stream_id, name);
 
+CREATE INDEX index_group_stages_on_stage_event_hash_id ON analytics_cycle_analytics_group_stages USING btree (stage_event_hash_id);
+
 CREATE UNIQUE INDEX index_group_wiki_repositories_on_disk_path ON group_wiki_repositories USING btree (disk_path);
 
 CREATE INDEX index_group_wiki_repositories_on_shard_id ON group_wiki_repositories USING btree (shard_id);
@@ -24762,6 +24787,8 @@ CREATE INDEX index_project_settings_on_project_id_partially ON project_settings
 
 CREATE UNIQUE INDEX index_project_settings_on_push_rule_id ON project_settings USING btree (push_rule_id);
 
+CREATE INDEX index_project_stages_on_stage_event_hash_id ON analytics_cycle_analytics_project_stages USING btree (stage_event_hash_id);
+
 CREATE INDEX index_project_statistics_on_namespace_id ON project_statistics USING btree (namespace_id);
 
 CREATE INDEX index_project_statistics_on_packages_size_and_project_id ON project_statistics USING btree (packages_size, project_id);
@@ -26073,6 +26100,9 @@ ALTER TABLE ONLY members
 ALTER TABLE ONLY lfs_objects_projects
     ADD CONSTRAINT fk_2eb33f7a78 FOREIGN KEY (project_id) REFERENCES projects(id) ON DELETE CASCADE NOT VALID;
 
+ALTER TABLE ONLY analytics_cycle_analytics_group_stages
+    ADD CONSTRAINT fk_3078345d6d FOREIGN KEY (stage_event_hash_id) REFERENCES analytics_cycle_analytics_stage_event_hashes(id) ON DELETE CASCADE;
+
 ALTER TABLE ONLY lists
     ADD CONSTRAINT fk_30f2a831f4 FOREIGN KEY (iteration_id) REFERENCES sprints(id) ON DELETE CASCADE;
 
@@ -26514,6 +26544,9 @@ ALTER TABLE ONLY packages_packages
 ALTER TABLE ONLY geo_event_log
     ADD CONSTRAINT fk_c1f241c70d FOREIGN KEY (upload_deleted_event_id) REFERENCES geo_upload_deleted_events(id) ON DELETE CASCADE;
 
+ALTER TABLE ONLY analytics_cycle_analytics_project_stages
+    ADD CONSTRAINT fk_c3339bdfc9 FOREIGN KEY (stage_event_hash_id) REFERENCES analytics_cycle_analytics_stage_event_hashes(id) ON DELETE CASCADE;
+
 ALTER TABLE ONLY vulnerability_exports
     ADD CONSTRAINT fk_c3d3cb5d0f FOREIGN KEY (group_id) REFERENCES namespaces(id) ON DELETE CASCADE;
 

ee/app/models/ee/analytics/cycle_analytics/stage_event_hash.rb

+# frozen_string_literal: true
+
+module EE
+  module Analytics
+    module CycleAnalytics
+      module StageEventHash
+        extend ActiveSupport::Concern
+
+        prepended do
+          has_many :cycle_analytics_group_stages, class_name: 'Analytics::CycleAnalytics::GroupStage', inverse_of: :stage_event_hash
+        end
+
+        class_methods do
+          def unused_hashes_for(id)
+            exists_query = ::Analytics::CycleAnalytics::GroupStage.where(stage_event_hash_id: id).select('1').limit(1)
+            super.where.not('EXISTS (?)', exists_query)
+          end
+        end
+      end
+    end
+  end
+end

ee/spec/models/ee/analytics/cycle_analytics/stage_event_hash_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Analytics::CycleAnalytics::StageEventHash, type: :model do
+  let(:stage_event_hash) { described_class.create!(hash_sha256: hash_sha256) }
+  let(:hash_sha256) { 'does_not_matter' }
+
+  describe 'associations' do
+    it { is_expected.to have_many(:cycle_analytics_group_stages) }
+  end
+
+  describe '.cleanup_if_unused' do
+    it 'removes the record if there is no project or group stages with given stage events hash' do
+      described_class.cleanup_if_unused(stage_event_hash.id)
+
+      expect(described_class.find_by_id(stage_event_hash.id)).to be_nil
+    end
+
+    it 'does not remove the record if at least 1 group stage for the given stage events hash exists' do
+      id = create(:cycle_analytics_group_stage).stage_event_hash_id
+
+      described_class.cleanup_if_unused(id)
+
+      expect(described_class.find_by_id(id)).not_to be_nil
+    end
+  end
+end

spec/models/analytics/cycle_analytics/stage_event_hash_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Analytics::CycleAnalytics::StageEventHash, type: :model do
+  let(:stage_event_hash) { described_class.create!(hash_sha256: hash_sha256) }
+  let(:hash_sha256) { 'does_not_matter' }
+
+  describe 'associations' do
+    it { is_expected.to have_many(:cycle_analytics_project_stages) }
+  end
+
+  describe 'validations' do
+    it { is_expected.to validate_presence_of(:hash_sha256) }
+  end
+
+  describe '.record_id_by_hash_sha256' do
+    it 'returns an existing id' do
+      id = stage_event_hash.id
+      same_id = described_class.record_id_by_hash_sha256(hash_sha256)
+
+      expect(same_id).to eq(id)
+    end
+
+    it 'creates a new record' do
+      expect do
+        described_class.record_id_by_hash_sha256(hash_sha256)
+      end.to change { described_class.count }.from(0).to(1)
+    end
+  end
+
+  describe '.cleanup_if_unused' do
+    it 'removes the record' do
+      described_class.cleanup_if_unused(stage_event_hash.id)
+
+      expect(described_class.find_by_id(stage_event_hash.id)).to be_nil
+    end
+
+    it 'does not remove the record' do
+      id = create(:cycle_analytics_project_stage).stage_event_hash_id
+
+      described_class.cleanup_if_unused(id)
+
+      expect(described_class.find_by_id(id)).not_to be_nil
+    end
+  end
+end

spec/support/shared_examples/models/cycle_analytics_stage_shared_examples.rb

@@ -13,6 +13,7 @@ RSpec.shared_examples 'value stream analytics stage' do
   describe 'associations' do
     it { is_expected.to belong_to(:end_event_label) }
     it { is_expected.to belong_to(:start_event_label) }
+    it { is_expected.to belong_to(:stage_event_hash) }
   end
 
   describe 'validation' do
@@ -138,6 +139,67 @@ RSpec.shared_examples 'value stream analytics stage' do
       expect(stage_1.events_hash_code).not_to eq(stage_2.events_hash_code)
     end
   end
+
+  # rubocop: disable Rails/SaveBang
+  describe '#event_hash' do
+    it 'associates the same stage event hash record' do
+      first = create(factory)
+      second = create(factory)
+
+      expect(first.stage_event_hash_id).to eq(second.stage_event_hash_id)
+    end
+
+    it 'does not introduce duplicated stage event hash records' do
+      expect do
+        create(factory)
+        create(factory)
+      end.to change { Analytics::CycleAnalytics::StageEventHash.count }.from(0).to(1)
+    end
+
+    it 'creates different hash record for different event configurations' do
+      expect do
+        create(factory, start_event_identifier: :issue_created, end_event_identifier: :issue_first_mentioned_in_commit)
+        create(factory, start_event_identifier: :merge_request_created, end_event_identifier: :merge_request_merged)
+      end.to change { Analytics::CycleAnalytics::StageEventHash.count }.from(0).to(2)
+    end
+
+    context 'when the stage event hash changes' do
+      let(:stage) { create(factory, start_event_identifier: :merge_request_created, end_event_identifier: :merge_request_merged) }
+
+      it 'deletes the old, unused stage event hash record' do
+        old_stage_event_hash = stage.stage_event_hash
+
+        stage.update!(end_event_identifier: :merge_request_first_deployed_to_production)
+
+        expect(stage.stage_event_hash_id).not_to eq(old_stage_event_hash.id)
+
+        old_stage_event_hash_from_db = Analytics::CycleAnalytics::StageEventHash.find_by_id(old_stage_event_hash.id)
+        expect(old_stage_event_hash_from_db).to be_nil
+      end
+
+      it 'does not delete used stage event hash record' do
+        other_stage = create(factory, start_event_identifier: :merge_request_created, end_event_identifier: :merge_request_merged)
+
+        stage.update!(end_event_identifier: :merge_request_first_deployed_to_production)
+
+        expect(stage.stage_event_hash_id).not_to eq(other_stage.stage_event_hash_id)
+
+        old_stage_event_hash_from_db = Analytics::CycleAnalytics::StageEventHash.find_by_id(other_stage.stage_event_hash_id)
+        expect(old_stage_event_hash_from_db).not_to be_nil
+      end
+    end
+
+    context 'when the stage events hash code does not change' do
+      it 'does not trigger extra query on save' do
+        stage = create(factory, start_event_identifier: :merge_request_created, end_event_identifier: :merge_request_merged)
+
+        expect(Analytics::CycleAnalytics::StageEventHash).not_to receive(:record_id_by_hash_sha256)
+
+        stage.update!(name: 'new title')
+      end
+    end
+  end
+  # rubocop: enable Rails/SaveBang
 end
 
 RSpec.shared_examples 'value stream analytics label based stage' do