sync: rollback if events have happened

If registry events have happened while performing a sync, then cancel
this process altogether. This should fix situations like:

1. User pushes image:tag.
2. Background process executes sync (because the registry task has
   already been executed before 1 happened).
3. Sync process marks image:tag as pushed by portus.

Signed-off-by: Miquel Sabaté Solà <[email protected]>

lib/portus/background/sync.rb

@@ -77,6 +77,16 @@ def update_registry!(catalog)
         portus = User.find_by(username: "portus")
         Tag.where(repository_id: dangling_repos).find_each { |t| t.delete_and_update!(portus) }
         Repository.where(id: dangling_repos).find_each { |r| r.delete_and_update!(portus) }
+
+        # Check that no events have happened while doing all this.
+        check_events!
+      end
+
+      # Raises an ActiveRecord::Rollback exception if there are registry events
+      # ready to be fetched.
+      def check_events!
+        return unless RegistryEvent.exists?(status: RegistryEvent.statuses[:fresh])
+        raise ActiveRecord::Rollback
       end
     end
   end

spec/api/grape_api/v1/vulnerabilities_spec.rb

@@ -2,7 +2,7 @@
 
 require "rails_helper"
 
-describe API::V1::Vulnerabilities, focus: true do
+describe API::V1::Vulnerabilities do
   let!(:admin) { create(:admin) }
   let!(:token) { create(:application_token, user: admin) }
   let!(:public_namespace) do

spec/lib/portus/background/sync_spec.rb

@@ -187,6 +187,23 @@ def update_registry!(catalog)
         expect(activities.last.key).to eq "repository.delete"
       end
     end
+
+    it "rolls back if an event happened while syncing" do
+      registry = create(:registry)
+      owner = create(:user)
+      repo = create(:repository, name: "repo", namespace: registry.global_namespace)
+      create(:tag, name: "latest", author: owner, repository: repo)
+
+      # Event!
+      RegistryEvent.create!(event_id: "id", data: "", status: RegistryEvent.statuses[:fresh])
+
+      allow_any_instance_of(::Portus::RegistryClient).to receive(:manifest).and_return(["", ""])
+      sync = SyncMock.new
+
+      expect do
+        sync.update_registry!([{ "name" => "repo", "tags" => ["0.1"] }])
+      end.to raise_error(ActiveRecord::Rollback)
+    end
   end
 
   describe "#enabled?" do