Mirror scheduling: Remove feature flag

This removes the feature flag update_all_mirrors_worker_rescheduling and
makes the new behavior the default while cleaning up code and specs.

Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/11499.
Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/5035.

ee/app/workers/repository_update_mirror_worker.rb

@@ -7,9 +7,6 @@ class RepositoryUpdateMirrorWorker
   include Gitlab::ShellAdapter
   include ProjectStartImport
 
-  LEASE_KEY = 'repository_update_mirror_worker_start_scheduler'.freeze
-  LEASE_TIMEOUT = 2.seconds
-
   # Retry not necessary. It will try again at the next update interval.
   sidekiq_options retry: false, status_expiration: StuckImportJobsWorker::IMPORT_JOBS_EXPIRATION
 
@@ -34,20 +31,10 @@ class RepositoryUpdateMirrorWorker
 
     fail_mirror(project, ex.message)
     raise UpdateError, "#{ex.class}: #{ex.message}"
-  ensure
-    unless Feature.enabled?(:update_all_mirrors_worker_rescheduling)
-      if !lease.exists? && lease.try_obtain && Gitlab::Mirror.reschedule_immediately?
-        UpdateAllMirrorsWorker.perform_async
-      end
-    end
   end
 
   private
 
-  def lease
-    @lease ||= ::Gitlab::ExclusiveLease.new(LEASE_KEY, timeout: LEASE_TIMEOUT)
-  end
-
   def start_mirror(project)
     import_state = project.import_state
 

ee/app/workers/update_all_mirrors_worker.rb

@@ -17,16 +17,14 @@ class UpdateAllMirrorsWorker
     # If we didn't get the lease, exit early
     return unless scheduling_ran
 
-    if Feature.enabled?(:update_all_mirrors_worker_rescheduling)
-      # Wait to give some jobs a chance to complete
-      Kernel.sleep(RESCHEDULE_WAIT)
-
-      # If there's capacity left now (some jobs completed),
-      # reschedule this job to enqueue more work.
-      #
-      # This is in addition to the regular (cron-like) scheduling of this job.
-      reschedule_if_capacity_left
-    end
+    # Wait to give some jobs a chance to complete
+    Kernel.sleep(RESCHEDULE_WAIT)
+
+    # If there's capacity left now (some jobs completed),
+    # reschedule this job to enqueue more work.
+    #
+    # This is in addition to the regular (cron-like) scheduling of this job.
+    reschedule_if_capacity_left
   end
 
   # rubocop: disable CodeReuse/ActiveRecord

ee/changelogs/unreleased/ab-11499-mirror-scheduling-featureflag.yml

+---
+title: Improve scheduling of mirror updates to reduce frequency of database queries
+merge_request: 11217
+author:
+type: performance

ee/spec/workers/repository_update_mirror_worker_spec.rb

 require 'rails_helper'
 
 describe RepositoryUpdateMirrorWorker do
-  include ExclusiveLeaseHelpers
-
   describe '#perform' do
     let(:jid) { '12345678' }
     let!(:project) { create(:project) }
@@ -50,51 +48,5 @@ describe RepositoryUpdateMirrorWorker do
         expect { subject.perform(started_project.id) }.to change { import_state.reload.status }.to('finished')
       end
     end
-
-    context 'reschedule mirrors' do
-      before do
-        allow_any_instance_of(Projects::UpdateMirrorService).to receive(:execute).and_return(status: :success)
-
-        stub_feature_flags(update_all_mirrors_worker_rescheduling: false)
-      end
-
-      context 'when we obtain the lease' do
-        before do
-          allow(stub_exclusive_lease).to receive(:exists?).and_return(false)
-        end
-
-        it 'performs UpdateAllMirrorsWorker when reschedule_immediately? returns true' do
-          allow(Gitlab::Mirror).to receive(:reschedule_immediately?).and_return(true)
-
-          expect(UpdateAllMirrorsWorker).to receive(:perform_async).once
-
-          subject.perform(project.id)
-        end
-
-        it 'does not perform UpdateAllMirrorsWorker when reschedule_immediately? returns false' do
-          allow(Gitlab::Mirror).to receive(:reschedule_immediately?).and_return(false)
-
-          expect(UpdateAllMirrorsWorker).not_to receive(:perform_async)
-
-          subject.perform(project.id)
-        end
-      end
-
-      it 'does not perform UpdateAllMirrorsWorker when we cannot obtain the lease' do
-        stub_exclusive_lease_taken
-
-        expect(UpdateAllMirrorsWorker).not_to receive(:perform_async)
-
-        subject.perform(project.id)
-      end
-
-      it 'does not perform UpdateAllMirrorsWorker when the lease already exists' do
-        stub_exclusive_lease_taken
-
-        expect(UpdateAllMirrorsWorker).not_to receive(:perform_async)
-
-        subject.perform(project.id)
-      end
-    end
   end
 end

ee/spec/workers/update_all_mirrors_worker_spec.rb

@@ -24,32 +24,26 @@ describe UpdateAllMirrorsWorker do
       worker.perform
     end
 
-    context 'with update_all_mirrors_worker_rescheduling feature' do
-      before do
-        stub_feature_flags(update_all_mirrors_worker_rescheduling: true)
-      end
-
-      it 'sleeps a bit after scheduling mirrors' do
-        expect(Kernel).to receive(:sleep).with(described_class::RESCHEDULE_WAIT)
+    it 'sleeps a bit after scheduling mirrors' do
+      expect(Kernel).to receive(:sleep).with(described_class::RESCHEDULE_WAIT)
 
-        worker.perform
-      end
+      worker.perform
+    end
 
-      it 'reschedules the job if capacity is left' do
-        allow(Gitlab::Mirror).to receive(:reschedule_immediately?).and_return(true)
+    it 'reschedules the job if capacity is left' do
+      allow(Gitlab::Mirror).to receive(:reschedule_immediately?).and_return(true)
 
-        expect(described_class).to receive(:perform_async)
+      expect(described_class).to receive(:perform_async)
 
-        worker.perform
-      end
+      worker.perform
+    end
 
-      it 'does not reschedule the job if no capacity left' do
-        allow(Gitlab::Mirror).to receive(:reschedule_immediately?).and_return(false)
+    it 'does not reschedule the job if no capacity left' do
+      allow(Gitlab::Mirror).to receive(:reschedule_immediately?).and_return(false)
 
-        expect(described_class).not_to receive(:perform_async)
+      expect(described_class).not_to receive(:perform_async)
 
-        worker.perform
-      end
+      worker.perform
     end
   end