Merge branch 'feature/improve-async-pipeline-processing' into 'master'

Improve asynchronous pipeline processing

## What does this MR do?

This MR improves asynchronous processing of pipeline.

## Why was this MR needed?

It eliminates some race conditions and improves performance.

## 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 / merge request numbers?

Related merge request:  !6410  
Extracted from !6411

See merge request !6650

2 files changed, 12 insertions, 8 deletions

diff --git a/app/models/ci/pipeline.rb b/app/models/ci/pipeline.rb
index 97df74b0cfe..2cf9892edc5 100644
--- a/app/models/ci/pipeline.rb
+++ b/app/models/ci/pipeline.rb
@@ -251,9 +251,8 @@ module Ci
       Ci::ProcessPipelineService.new(project, user).execute(self)
     end
 
-    def build_updated
+    def update_status
       with_lock do
-        reload
         case latest_builds_status
         when 'pending' then enqueue
         when 'running' then run
diff --git a/app/models/commit_status.rb b/app/models/commit_status.rb
index ee3396abe04..9fa8d17e74e 100644
--- a/app/models/commit_status.rb
+++ b/app/models/commit_status.rb
@@ -84,13 +84,18 @@ class CommitStatus < ActiveRecord::Base
       commit_status.update_attributes finished_at: Time.now
     end
 
-    after_transition any => [:success, :failed, :canceled] do |commit_status|
-      commit_status.pipeline.try(:process!)
-      true
-    end
-
     after_transition do |commit_status, transition|
-      commit_status.pipeline.try(:build_updated) unless transition.loopback?
+      commit_status.pipeline.try do |pipeline|
+        break if transition.loopback?
+
+        if commit_status.complete?
+          ProcessPipelineWorker.perform_async(pipeline.id)
+        end
+
+        UpdatePipelineWorker.perform_async(pipeline.id)
+      end
+
+      true
     end
 
     after_transition [:created, :pending, :running] => :success do |commit_status|