1 files changed, 40 insertions, 0 deletions
diff --git a/app/services/ci/register_build_service.rb b/app/services/ci/register_build_service.rb
new file mode 100644
index 00000000000..7e0b58a5dc9
--- /dev/null
+++ b/app/services/ci/register_build_service.rb
@@ -0,0 +1,40 @@
+module Ci
+  # This class responsible for assigning
+  # proper pending build to runner on runner API request
+  class RegisterBuildService
+    def execute(current_runner)
+      builds = Ci::Build.pending.unstarted
+
+      builds =
+        if current_runner.shared?
+          # don't run projects which have not enables shared runners
+          builds.includes(:project).where(projects: { shared_runners_enabled: true })
+        else
+          # do run projects which are only assigned to this runner
+          builds.where(project_id: current_runner.projects)
+        end
+
+      builds = builds.order('created_at ASC')
+
+      build = builds.find do |build|
+        (build.tag_list - current_runner.tag_list).empty?
+      end
+        
+
+      if build
+        # In case when 2 runners try to assign the same build, second runner will be declined
+        # with StateMachine::InvalidTransition in run! method.
+        build.with_lock do
+          build.runner_id = current_runner.id
+          build.save!
+          build.run!
+        end
+      end
+
+      build
+
+    rescue StateMachine::InvalidTransition
+      nil
+    end
+  end
+end