Merge branch 'fix/build-erase-race-condition' into 'master'

Avoid race condition when expiring artifacts

## What does this MR do?

It may happen that job which purpose is to remove expired artifacts will be executed asynchronously when, in the meantime, project associated with given build gets removed by another async job. In that case we should not remove artifacts because such build will be eventually removed anyway along with artifacts, when project removal is complete.

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] Added for this feature/bug
  - [x] All builds are passing

## What are the relevant issue numbers?

Closes #22296

See merge request !6881

CHANGELOG.md

@@ -2,6 +2,7 @@ Please view this file on the master branch, on stable branches it's out of date.
 
 ## 8.13.0 (2016-10-22)
 
+  - Avoid race condition when asynchronously removing expired artifacts. (!6881)
   - Improve Merge When Build Succeeds triggers and execute on pipeline success. (!6675)
   - Respond with 404 Not Found for non-existent tags (Linus Thiel)
   - Truncate long labels with ellipsis in labels page

app/workers/expire_build_instance_artifacts_worker.rb

@@ -2,10 +2,14 @@ class ExpireBuildInstanceArtifactsWorker
   include Sidekiq::Worker
 
   def perform(build_id)
-    build = Ci::Build.with_expired_artifacts.reorder(nil).find_by(id: build_id)
-    return unless build
+    build = Ci::Build
+      .with_expired_artifacts
+      .reorder(nil)
+      .find_by(id: build_id)
 
-    Rails.logger.info "Removing artifacts build #{build.id}..."
+    return unless build.try(:project)
+
+    Rails.logger.info "Removing artifacts for build #{build.id}..."
     build.erase_artifacts!
   end
 end

spec/workers/expire_build_instance_artifacts_worker_spec.rb

@@ -6,28 +6,48 @@ describe ExpireBuildInstanceArtifactsWorker do
   let(:worker) { described_class.new }
 
   describe '#perform' do
-    before { build }
-
-    subject! { worker.perform(build.id) }
+    before do
+      worker.perform(build.id)
+    end
 
     context 'with expired artifacts' do
-      let(:build) { create(:ci_build, :artifacts, artifacts_expire_at: Time.now - 7.days) }
+      let(:artifacts_expiry) { { artifacts_expire_at: Time.now - 7.days } }
 
-      it 'does expire' do
-        expect(build.reload.artifacts_expired?).to be_truthy
-      end
+      context 'when associated project is valid' do
+        let(:build) do
+          create(:ci_build, :artifacts, artifacts_expiry)
+        end
 
-      it 'does remove files' do
-        expect(build.reload.artifacts_file.exists?).to be_falsey
+        it 'does expire' do
+          expect(build.reload.artifacts_expired?).to be_truthy
+        end
+
+        it 'does remove files' do
+          expect(build.reload.artifacts_file.exists?).to be_falsey
+        end
+
+        it 'does nullify artifacts_file column' do
+          expect(build.reload.artifacts_file_identifier).to be_nil
+        end
       end
 
-      it 'does nullify artifacts_file column' do
-        expect(build.reload.artifacts_file_identifier).to be_nil
+      context 'when associated project was removed' do
+        let(:build) do
+          create(:ci_build, :artifacts, artifacts_expiry) do |build|
+            build.project.delete
+          end
+        end
+
+        it 'does not remove artifacts' do
+          expect(build.reload.artifacts_file.exists?).to be_truthy
+        end
       end
     end
 
     context 'with not yet expired artifacts' do
-      let(:build) { create(:ci_build, :artifacts, artifacts_expire_at: Time.now + 7.days) }
+      let(:build) do
+        create(:ci_build, :artifacts, artifacts_expire_at: Time.now + 7.days)
+      end
 
       it 'does not expire' do
         expect(build.reload.artifacts_expired?).to be_falsey