Merge branch 'background-migrations-system-load' into 'master'

Respond to DB health in background migrations

See merge request gitlab-org/gitlab-ce!20720

1 files changed, 52 insertions, 0 deletions

diff --git a/spec/workers/background_migration_worker_spec.rb b/spec/workers/background_migration_worker_spec.rb
index d67e7698635..3bd072e7125 100644
--- a/spec/workers/background_migration_worker_spec.rb
+++ b/spec/workers/background_migration_worker_spec.rb
@@ -3,6 +3,12 @@ require 'spec_helper'
 describe BackgroundMigrationWorker, :sidekiq, :clean_gitlab_redis_shared_state do
   let(:worker) { described_class.new }
 
+  describe '.minimum_interval' do
+    it 'returns 2 minutes' do
+      expect(described_class.minimum_interval).to eq(2.minutes.to_i)
+    end
+  end
+
   describe '.perform' do
     it 'performs a background migration' do
       expect(Gitlab::BackgroundMigration)
@@ -28,5 +34,51 @@ describe BackgroundMigrationWorker, :sidekiq, :clean_gitlab_redis_shared_state d
 
       worker.perform('Foo', [10, 20])
     end
+
+    it 'reschedules a migration if the database is not healthy' do
+      allow(worker)
+        .to receive(:always_perform?)
+        .and_return(false)
+
+      allow(worker)
+        .to receive(:healthy_database?)
+        .and_return(false)
+
+      expect(described_class)
+        .to receive(:perform_in)
+        .with(a_kind_of(Numeric), 'Foo', [10, 20])
+
+      worker.perform('Foo', [10, 20])
+    end
+  end
+
+  describe '#healthy_database?' do
+    context 'using MySQL', :mysql do
+      it 'returns true' do
+        expect(worker.healthy_database?).to eq(true)
+      end
+    end
+
+    context 'using PostgreSQL', :postgresql do
+      context 'when replication lag is too great' do
+        it 'returns false' do
+          allow(Postgresql::ReplicationSlot)
+            .to receive(:lag_too_great?)
+            .and_return(true)
+
+          expect(worker.healthy_database?).to eq(false)
+        end
+      end
+
+      context 'when replication lag is small enough' do
+        it 'returns true' do
+          allow(Postgresql::ReplicationSlot)
+            .to receive(:lag_too_great?)
+            .and_return(false)
+
+          expect(worker.healthy_database?).to eq(true)
+        end
+      end
+    end
   end
 end