Create migration to schedule re-population of historical stats

db/post_migrate/20201119092319_schedule_repopulate_historical_vulnerability_statistics.rb

+# frozen_string_literal: true
+
+class ScheduleRepopulateHistoricalVulnerabilityStatistics < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+  BATCH_SIZE = 50
+  DELAY_INTERVAL = 5.minutes
+  MIGRATION_CLASS = 'PopulateVulnerabilityHistoricalStatistics'
+  DAY_COUNT = 365
+
+  disable_ddl_transaction!
+
+  class ProjectSetting < ActiveRecord::Base
+    include EachBatch
+
+    self.table_name = 'project_settings'
+
+    scope :has_vulnerabilities, -> { where('has_vulnerabilities IS TRUE') }
+  end
+
+  def up
+    ProjectSetting.has_vulnerabilities.each_batch(of: BATCH_SIZE) do |batch, index|
+      migrate_in(index * DELAY_INTERVAL, MIGRATION_CLASS, [batch.pluck(:project_id), DAY_COUNT])
+    end
+  end
+
+  def down
+    # no-op
+  end
+end

db/schema_migrations/20201119092319

+9ff8ddefff1df81f1eac2ccfc6f3019bb77a6129280e799c0abe54f51e09277a
\ No newline at end of file

spec/migrations/schedule_repopulate_historical_vulnerability_statistics_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+require_migration!
+
+RSpec.describe ScheduleRepopulateHistoricalVulnerabilityStatistics do
+  let(:namespaces) { table(:namespaces) }
+  let(:projects) { table(:projects) }
+  let(:project_settings) { table(:project_settings) }
+
+  let(:namespace) { namespaces.create!(name: 'gitlab', path: 'gitlab-org') }
+  let!(:project_1) { projects.create!(namespace_id: namespace.id, name: 'foo_1') }
+  let!(:project_2) { projects.create!(namespace_id: namespace.id, name: 'foo_2') }
+  let!(:project_3) { projects.create!(namespace_id: namespace.id, name: 'foo_3') }
+  let!(:project_4) { projects.create!(namespace_id: namespace.id, name: 'foo_4') }
+
+  around do |example|
+    freeze_time { Sidekiq::Testing.fake! { example.run } }
+  end
+
+  before do
+    stub_const("#{described_class.name}::BATCH_SIZE", 1)
+
+    project_settings.create!(project_id: project_1.id, has_vulnerabilities: true)
+    project_settings.create!(project_id: project_2.id, has_vulnerabilities: false)
+    project_settings.create!(project_id: project_4.id, has_vulnerabilities: true)
+  end
+
+  it 'schedules the background jobs', :aggregate_failures do
+    migrate!
+
+    expect(BackgroundMigrationWorker.jobs.size).to be(2)
+    expect(described_class::MIGRATION_CLASS).to be_scheduled_delayed_migration(described_class::DELAY_INTERVAL, [project_1.id], described_class::DAY_COUNT)
+    expect(described_class::MIGRATION_CLASS).to be_scheduled_delayed_migration(2 * described_class::DELAY_INTERVAL, [project_4.id], described_class::DAY_COUNT)
+  end
+end