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? builds. # don't run projects which have not enabled shared runners and builds joins(:project).where(projects: { shared_runners_enabled: true }). joins('LEFT JOIN project_features ON ci_builds.gl_project_id = project_features.project_id'). # this returns builds that are ordered by number of running builds # we prefer projects that don't use shared runners at all joins("LEFT JOIN (#{running_builds_for_shared_runners.to_sql}) AS project_builds ON ci_builds.gl_project_id=project_builds.gl_project_id"). where('project_features.builds_access_level IS NULL or project_features.builds_access_level > 0'). order('COALESCE(project_builds.running_builds, 0) ASC', 'ci_builds.id ASC') else # do run projects which are only assigned to this runner (FIFO) builds.where(project: current_runner.projects.with_builds_enabled).order('created_at ASC') end build = builds.find do |build| current_runner.can_pick?(build) end if build # In case when 2 runners try to assign the same build, second runner will be declined # with StateMachines::InvalidTransition in run! method. build.with_lock do build.runner_id = current_runner.id build.save! build.run! end end build rescue StateMachines::InvalidTransition nil end private def running_builds_for_shared_runners Ci::Build.running.where(runner: Ci::Runner.shared). group(:gl_project_id).select(:gl_project_id, 'count(*) AS running_builds') end end end