Merge branch 'master' into go-go-gadget-webpack

* master: (389 commits)
  Document "No gems fetched from git repositories" policy [ci skip]
  Typos
  Small gramatical tweaks
  Typos
  Added PHP & NPM doc
  Use `:empty_project` where possible in request specs
  Add caching of droplab ajax requests
  Use `:empty_project` where possible in model specs
  Revert 3f17f29a
  Remove unused js response from refs controller
  Add MR id to changelog entry
  fixed small mini pipeline graph line glitch
  Prevent form to be submitted twice
  Fix Error 500 when repositories contain annotated tags pointing to blobs
  Fix /explore sorting (trending)
  Simplify wording in "adding an image" docs
  Remove "official merge window" from CONTRIBUTING.md [ci skip]
  Update repository check documentation
  Fixed flexbox and wrap issues
  Update two_factor_authentication.md
  ...

1 files changed, 43 insertions, 19 deletions

diff --git a/app/services/ci/register_build_service.rb b/app/services/ci/register_build_service.rb
index 74b5ebf372b..6f03bf2be13 100644
--- a/app/services/ci/register_build_service.rb
+++ b/app/services/ci/register_build_service.rb
@@ -2,48 +2,72 @@ 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
+    include Gitlab::CurrentSettings
 
+    attr_reader :runner
+
+    Result = Struct.new(:build, :valid?)
+
+    def initialize(runner)
+      @runner = runner
+    end
+
+    def execute
       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')
+        if runner.shared?
+          builds_for_shared_runner
         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')
+          builds_for_specific_runner
         end
 
       build = builds.find do |build|
-        current_runner.can_pick?(build)
+        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 or StaleObjectError when doing run! or save method.
-        build.runner_id = current_runner.id
+        build.runner_id = runner.id
         build.run!
       end
 
-      build
+      Result.new(build, true)
 
     rescue StateMachines::InvalidTransition, ActiveRecord::StaleObjectError
-      nil
+      Result.new(build, false)
     end
 
     private
 
+    def builds_for_shared_runner
+      new_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').
+        where('project_features.builds_access_level IS NULL or project_features.builds_access_level > 0').
+
+        # Implement fair scheduling
+        # 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").
+        order('COALESCE(project_builds.running_builds, 0) ASC', 'ci_builds.id ASC')
+    end
+
+    def builds_for_specific_runner
+      new_builds.where(project: runner.projects.with_builds_enabled).order('created_at ASC')
+    end
+
     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
+
+    def new_builds
+      Ci::Build.pending.unstarted
+    end
+
+    def shared_runner_build_limits_feature_enabled?
+      ENV['DISABLE_SHARED_RUNNER_BUILD_MINUTES_LIMIT'].to_s != 'true'
+    end
   end
 end