Merge branch 'improve-pipeline-processing' into 'master'

Improve pipeline processing

## What does this MR do?
This works on top of https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5295 trying to solve some edge cases introduced by that Merge Request. The fix switches to a state machine which is already a part of `Ci::Pipeline` and uses events with conditional transitions to switch between pipeline states.

This is approach is much more bullet proof and much easier to understand than a previous one where we were calling a `reload_status!` which manually updated `status`. Previous approach become confusing and prone to number of errors.

## Why was this MR needed?
This improves changes introduced by https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5295

## What are the relevant issue numbers?
None, yet.

## Screenshots (if relevant)
Not needed.

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added (not needed since changelog for https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5295 is already introduced)
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [x] API support added (not needed)
- Tests
  - [x] Added for this feature/bug (most of tests do cover the triggering of Pipeline)
  - [ ] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [ ] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !5782

12 files changed, 214 insertions, 113 deletions

diff --git a/app/models/ci/build.rb b/app/models/ci/build.rb
index 88a340379b8..3d6c6ea3209 100644
--- a/app/models/ci/build.rb
+++ b/app/models/ci/build.rb
@@ -42,24 +42,25 @@ module Ci
       end
 
       def retry(build, user = nil)
-        new_build = Ci::Build.new(status: 'pending')
-        new_build.ref = build.ref
-        new_build.tag = build.tag
-        new_build.options = build.options
-        new_build.commands = build.commands
-        new_build.tag_list = build.tag_list
-        new_build.project = build.project
-        new_build.pipeline = build.pipeline
-        new_build.name = build.name
-        new_build.allow_failure = build.allow_failure
-        new_build.stage = build.stage
-        new_build.stage_idx = build.stage_idx
-        new_build.trigger_request = build.trigger_request
-        new_build.yaml_variables = build.yaml_variables
-        new_build.when = build.when
-        new_build.user = user
-        new_build.environment = build.environment
-        new_build.save
+        new_build = Ci::Build.create(
+          ref: build.ref,
+          tag: build.tag,
+          options: build.options,
+          commands: build.commands,
+          tag_list: build.tag_list,
+          project: build.project,
+          pipeline: build.pipeline,
+          name: build.name,
+          allow_failure: build.allow_failure,
+          stage: build.stage,
+          stage_idx: build.stage_idx,
+          trigger_request: build.trigger_request,
+          yaml_variables: build.yaml_variables,
+          when: build.when,
+          user: user,
+          environment: build.environment,
+          status_event: 'enqueue'
+        )
         MergeRequests::AddTodoWhenBuildFailsService.new(build.project, nil).close(new_build)
         new_build
       end
@@ -101,7 +102,7 @@ module Ci
 
     def play(current_user = nil)
       # Try to queue a current build
-      if self.queue
+      if self.enqueue
         self.update(user: current_user)
         self
       else
diff --git a/app/models/ci/pipeline.rb b/app/models/ci/pipeline.rb
index 718fe3290c1..8cfba92ae9b 100644
--- a/app/models/ci/pipeline.rb
+++ b/app/models/ci/pipeline.rb
@@ -19,6 +19,45 @@ module Ci
 
     after_save :keep_around_commits
 
+    state_machine :status, initial: :created do
+      event :enqueue do
+        transition created: :pending
+        transition [:success, :failed, :canceled, :skipped] => :running
+      end
+
+      event :run do
+        transition any => :running
+      end
+
+      event :skip do
+        transition any => :skipped
+      end
+
+      event :drop do
+        transition any => :failed
+      end
+
+      event :succeed do
+        transition any => :success
+      end
+
+      event :cancel do
+        transition any => :canceled
+      end
+
+      before_transition [:created, :pending] => :running do |pipeline|
+        pipeline.started_at = Time.now
+      end
+
+      before_transition any => [:success, :failed, :canceled] do |pipeline|
+        pipeline.finished_at = Time.now
+      end
+
+      before_transition do |pipeline|
+        pipeline.update_duration
+      end
+    end
+
     # ref can't be HEAD or SHA, can only be branch/tag name
     scope :latest_successful_for, ->(ref = default_branch) do
       where(ref: ref).success.order(id: :desc).limit(1)
@@ -89,16 +128,12 @@ module Ci
 
     def cancel_running
       builds.running_or_pending.each(&:cancel)
-
-      reload_status!
     end
 
     def retry_failed(user)
       builds.latest.failed.select(&:retryable?).each do |build|
         Ci::Build.retry(build, user)
       end
-
-      reload_status!
     end
 
     def latest?
@@ -185,7 +220,17 @@ module Ci
 
     def process!
       Ci::ProcessPipelineService.new(project, user).execute(self)
-      reload_status!
+    end
+
+    def build_updated
+      case latest_builds_status
+      when 'pending' then enqueue
+      when 'running' then run
+      when 'success' then succeed
+      when 'failed' then drop
+      when 'canceled' then cancel
+      when 'skipped' then skip
+      end
     end
 
     def predefined_variables
@@ -194,22 +239,18 @@ module Ci
       ]
     end
 
-    def reload_status!
-      statuses.reload
-      self.status =
-        if yaml_errors.blank?
-          statuses.latest.status || 'skipped'
-        else
-          'failed'
-        end
-      self.started_at = statuses.started_at
-      self.finished_at = statuses.finished_at
+    def update_duration
       self.duration = statuses.latest.duration
-      save
     end
 
     private
 
+    def latest_builds_status
+      return 'failed' unless yaml_errors.blank?
+
+      statuses.latest.status || 'skipped'
+    end
+
     def keep_around_commits
       return unless project
 
diff --git a/app/models/commit_status.rb b/app/models/commit_status.rb
index 20713314a25..703ca90edb6 100644
--- a/app/models/commit_status.rb
+++ b/app/models/commit_status.rb
@@ -26,7 +26,7 @@ class CommitStatus < ActiveRecord::Base
   scope :ignored, -> { where(allow_failure: true, status: [:failed, :canceled]) }
 
   state_machine :status do
-    event :queue do
+    event :enqueue do
       transition [:created, :skipped] => :pending
     end
 
@@ -62,6 +62,17 @@ class CommitStatus < ActiveRecord::Base
       commit_status.update_attributes finished_at: Time.now
     end
 
+    # We use around_transition to process pipeline on next stages as soon as possible, before the `after_*` is executed
+    around_transition any => [:success, :failed, :canceled] do |commit_status, block|
+      block.call
+
+      commit_status.pipeline.try(:process!)
+    end
+
+    after_transition do |commit_status, transition|
+      commit_status.pipeline.try(:build_updated) unless transition.loopback?
+    end
+
     after_transition [:created, :pending, :running] => :success do |commit_status|
       MergeRequests::MergeWhenBuildSucceedsService.new(commit_status.pipeline.project, nil).trigger(commit_status)
     end
@@ -69,13 +80,6 @@ class CommitStatus < ActiveRecord::Base
     after_transition any => :failed do |commit_status|
       MergeRequests::AddTodoWhenBuildFailsService.new(commit_status.pipeline.project, nil).execute(commit_status)
     end
-
-    # We use around_transition to process pipeline on next stages as soon as possible, before the `after_*` is executed
-    around_transition any => [:success, :failed, :canceled] do |commit_status, block|
-      block.call
-
-      commit_status.pipeline.process! if commit_status.pipeline
-    end
   end
 
   delegate :sha, :short_sha, to: :pipeline
diff --git a/app/services/ci/create_pipeline_service.rb b/app/services/ci/create_pipeline_service.rb
index 7398fd8e10a..cde856b0186 100644
--- a/app/services/ci/create_pipeline_service.rb
+++ b/app/services/ci/create_pipeline_service.rb
@@ -37,7 +37,8 @@ module Ci
       end
 
       if !ignore_skip_ci && skip_ci?
-        return error('Creation of pipeline is skipped', save: save_on_errors)
+        pipeline.skip if save_on_errors
+        return pipeline
       end
 
       unless pipeline.config_builds_attributes.present?
@@ -93,7 +94,7 @@ module Ci
 
     def error(message, save: false)
       pipeline.errors.add(:base, message)
-      pipeline.reload_status! if save
+      pipeline.drop if save
       pipeline
     end
   end
diff --git a/app/services/ci/process_pipeline_service.rb b/app/services/ci/process_pipeline_service.rb
index 86c4823d18a..6f7610d42ba 100644
--- a/app/services/ci/process_pipeline_service.rb
+++ b/app/services/ci/process_pipeline_service.rb
@@ -37,7 +37,7 @@ module Ci
       return false unless Statuseable::COMPLETED_STATUSES.include?(current_status)
 
       if valid_statuses_for_when(build.when).include?(current_status)
-        build.queue
+        build.enqueue
         true
       else
         build.skip
diff --git a/features/steps/shared/builds.rb b/features/steps/shared/builds.rb
index c7f61da05fa..70e6d4836b2 100644
--- a/features/steps/shared/builds.rb
+++ b/features/steps/shared/builds.rb
@@ -12,7 +12,6 @@ module SharedBuilds
   step 'project has a recent build' do
     @pipeline = create(:ci_empty_pipeline, project: @project, sha: @project.commit.sha, ref: 'master')
     @build = create(:ci_build_with_coverage, pipeline: @pipeline)
-    @pipeline.reload_status!
   end
 
   step 'recent build is successful' do
@@ -24,8 +23,7 @@ module SharedBuilds
   end
 
   step 'project has another build that is running' do
-    create(:ci_build, pipeline: @pipeline, name: 'second build', status: 'running')
-    @pipeline.reload_status!
+    create(:ci_build, pipeline: @pipeline, name: 'second build', status_event: 'run')
   end
 
   step 'I visit recent build details page' do
diff --git a/spec/features/projects/pipelines_spec.rb b/spec/features/projects/pipelines_spec.rb
index c39bb7ffa37..29d150bc597 100644
--- a/spec/features/projects/pipelines_spec.rb
+++ b/spec/features/projects/pipelines_spec.rb
@@ -12,7 +12,7 @@ describe "Pipelines" do
   end
 
   describe 'GET /:project/pipelines' do
-    let!(:pipeline) { create(:ci_pipeline, project: project, ref: 'master', status: 'running') }
+    let!(:pipeline) { create(:ci_empty_pipeline, project: project, ref: 'master', status: 'running') }
 
     [:all, :running, :branches].each do |scope|
       context "displaying #{scope}" do
@@ -31,10 +31,10 @@ describe "Pipelines" do
     end
 
     context 'cancelable pipeline' do
-      let!(:running) { create(:ci_build, :running, pipeline: pipeline, stage: 'test', commands: 'test') }
+      let!(:build) { create(:ci_build, pipeline: pipeline, stage: 'test', commands: 'test') }
 
       before do
-        pipeline.reload_status!
+        build.run
         visit namespace_project_pipelines_path(project.namespace, project)
       end
 
@@ -50,10 +50,10 @@ describe "Pipelines" do
     end
 
     context 'retryable pipelines' do
-      let!(:failed) { create(:ci_build, :failed, pipeline: pipeline, stage: 'test', commands: 'test') }
+      let!(:build) { create(:ci_build, pipeline: pipeline, stage: 'test', commands: 'test') }
 
       before do
-        pipeline.reload_status!
+        build.drop
         visit namespace_project_pipelines_path(project.namespace, project)
       end
 
@@ -64,7 +64,7 @@ describe "Pipelines" do
         before { click_link('Retry') }
 
         it { expect(page).not_to have_link('Retry') }
-        it { expect(page).to have_selector('.ci-pending') }
+        it { expect(page).to have_selector('.ci-running') }
       end
     end
 
@@ -87,7 +87,6 @@ describe "Pipelines" do
         let!(:running) { create(:generic_commit_status, status: 'running', pipeline: pipeline, stage: 'test') }
 
         before do
-          pipeline.reload_status!
           visit namespace_project_pipelines_path(project.namespace, project)
         end
 
@@ -101,10 +100,10 @@ describe "Pipelines" do
       end
 
       context 'when failed' do
-        let!(:failed) { create(:generic_commit_status, status: 'failed', pipeline: pipeline, stage: 'test') }
+        let!(:status) { create(:generic_commit_status, :pending, pipeline: pipeline, stage: 'test') }
 
         before do
-          pipeline.reload_status!
+          status.drop
           visit namespace_project_pipelines_path(project.namespace, project)
         end
 
diff --git a/spec/lib/ci/charts_spec.rb b/spec/lib/ci/charts_spec.rb
index 2cd6b00dad6..fb6cc398307 100644
--- a/spec/lib/ci/charts_spec.rb
+++ b/spec/lib/ci/charts_spec.rb
@@ -2,22 +2,23 @@ require 'spec_helper'
 
 describe Ci::Charts, lib: true do
   context "build_times" do
+    let(:project) { create(:empty_project) }
+    let(:chart) { Ci::Charts::BuildTime.new(project) }
+
+    subject { chart.build_times }
+
     before do
-      @pipeline = FactoryGirl.create(:ci_pipeline)
-      FactoryGirl.create(:ci_build, pipeline: @pipeline)
-      @pipeline.reload_status!
+      create(:ci_empty_pipeline, project: project, duration: 120)
     end
 
     it 'returns build times in minutes' do
-      chart = Ci::Charts::BuildTime.new(@pipeline.project)
-      expect(chart.build_times).to eq([2])
+      is_expected.to contain_exactly(2)
     end
 
     it 'handles nil build times' do
-      create(:ci_pipeline, duration: nil, project: @pipeline.project)
+      create(:ci_empty_pipeline, project: project, duration: nil)
 
-      chart = Ci::Charts::BuildTime.new(@pipeline.project)
-      expect(chart.build_times).to eq([2, 0])
+      is_expected.to contain_exactly(2, 0)
     end
   end
 end
diff --git a/spec/models/build_spec.rb b/spec/models/build_spec.rb
index 60a221eba50..5980f6ddc32 100644
--- a/spec/models/build_spec.rb
+++ b/spec/models/build_spec.rb
@@ -886,8 +886,10 @@ describe Ci::Build, models: true do
       is_expected.to eq(build)
     end
 
-    context 'for success build' do
-      before { build.queue }
+    context 'for successful build' do
+      before do
+        build.update(status: 'success')
+      end
 
       it 'creates a new build' do
         is_expected.to be_pending
diff --git a/spec/models/ci/pipeline_spec.rb b/spec/models/ci/pipeline_spec.rb
index fdb579ab45c..950833cb219 100644
--- a/spec/models/ci/pipeline_spec.rb
+++ b/spec/models/ci/pipeline_spec.rb
@@ -2,7 +2,7 @@ require 'spec_helper'
 
 describe Ci::Pipeline, models: true do
   let(:project) { FactoryGirl.create :empty_project }
-  let(:pipeline) { FactoryGirl.create :ci_pipeline, project: project }
+  let(:pipeline) { FactoryGirl.create :ci_empty_pipeline, project: project }
 
   it { is_expected.to belong_to(:project) }
   it { is_expected.to belong_to(:user) }
@@ -51,25 +51,6 @@ describe Ci::Pipeline, models: true do
     end
   end
 
-  describe "#finished_at" do
-    let(:pipeline) { FactoryGirl.create :ci_pipeline }
-
-    it "returns finished_at of latest build" do
-      build = FactoryGirl.create :ci_build, pipeline: pipeline, finished_at: Time.now - 60
-      FactoryGirl.create :ci_build, pipeline: pipeline, finished_at: Time.now - 120
-      pipeline.reload_status!
-
-      expect(pipeline.finished_at.to_i).to eq(build.finished_at.to_i)
-    end
-
-    it "returns nil if there is no finished build" do
-      FactoryGirl.create :ci_not_started_build, pipeline: pipeline
-      pipeline.reload_status!
-
-      expect(pipeline.finished_at).to be_nil
-    end
-  end
-
   describe "coverage" do
     let(:project) { FactoryGirl.create :empty_project, build_coverage_regex: "/.*/" }
     let(:pipeline) { FactoryGirl.create :ci_empty_pipeline, project: project }
@@ -139,32 +120,47 @@ describe Ci::Pipeline, models: true do
     end
   end
 
-  describe '#reload_status!' do
-    let(:pipeline) { create :ci_empty_pipeline, project: project }
+  describe 'state machine' do
+    let(:current) { Time.now.change(usec: 0) }
+    let(:build) { create :ci_build, name: 'build1', pipeline: pipeline, started_at: current - 60, finished_at: current }
+    let(:build2) { create :ci_build, name: 'build2', pipeline: pipeline, started_at: current - 60, finished_at: current }
 
-    context 'dependent objects' do
-      let(:commit_status) { create :commit_status, :pending, pipeline: pipeline }
+    describe '#duration' do
+      before do
+        build.skip
+        build2.skip
+      end
 
-      it 'executes reload_status! after succeeding dependent object' do
-        expect(pipeline).to receive(:reload_status!).and_return(true)
+      it 'matches sum of builds duration' do
+        expect(pipeline.reload.duration).to eq(build.duration + build2.duration)
+      end
+    end
+
+    describe '#started_at' do
+      it 'updates on transitioning to running' do
+        build.run
 
-        commit_status.success
+        expect(pipeline.reload.started_at).not_to be_nil
+      end
+
+      it 'does not update on transitioning to success' do
+        build.success
+
+        expect(pipeline.reload.started_at).to be_nil
       end
     end
 
-    context 'updates' do
-      let(:current) { Time.now.change(usec: 0) }
-      let(:build) { FactoryGirl.create :ci_build, pipeline: pipeline, started_at: current - 120, finished_at: current - 60 }
+    describe '#finished_at' do
+      it 'updates on transitioning to success' do
+        build.success
 
-      before do
-        build
-        pipeline.reload_status!
+        expect(pipeline.reload.finished_at).not_to be_nil
       end
 
-      [:status, :started_at, :finished_at, :duration].each do |param|
-        it "#{param}" do
-          expect(pipeline.send(param)).to eq(build.send(param))
-        end
+      it 'does not update on transitioning to running' do
+        build.run
+
+        expect(pipeline.reload.finished_at).to be_nil
       end
     end
   end
@@ -254,4 +250,64 @@ describe Ci::Pipeline, models: true do
       end
     end
   end
+
+  describe '#status' do
+    let!(:build) { create(:ci_build, :created, pipeline: pipeline, name: 'test') }
+
+    subject { pipeline.reload.status }
+
+    context 'on queuing' do
+      before do
+        build.enqueue
+      end
+
+      it { is_expected.to eq('pending') }
+    end
+
+    context 'on run' do
+      before do
+        build.enqueue
+        build.run
+      end
+
+      it { is_expected.to eq('running') }
+    end
+
+    context 'on drop' do
+      before do
+        build.drop
+      end
+
+      it { is_expected.to eq('failed') }
+    end
+
+    context 'on success' do
+      before do
+        build.success
+      end
+
+      it { is_expected.to eq('success') }
+    end
+
+    context 'on cancel' do
+      before do
+        build.cancel
+      end
+
+      it { is_expected.to eq('canceled') }
+    end
+
+    context 'on failure and build retry' do
+      before do
+        build.drop
+        Ci::Build.retry(build)
+      end
+
+      # We are changing a state: created > failed > running
+      # Instead of: created > failed > pending
+      # Since the pipeline already run, so it should not be pending anymore
+
+      it { is_expected.to eq('running') }
+    end
+  end
 end
diff --git a/spec/requests/api/builds_spec.rb b/spec/requests/api/builds_spec.rb
index a4cdd8f3140..41503885dd9 100644
--- a/spec/requests/api/builds_spec.rb
+++ b/spec/requests/api/builds_spec.rb
@@ -9,7 +9,7 @@ describe API::API, api: true do
   let!(:developer) { create(:project_member, :developer, user: user, project: project) }
   let(:reporter) { create(:project_member, :reporter, project: project) }
   let(:guest) { create(:project_member, :guest, project: project) }
-  let!(:pipeline) { create(:ci_pipeline, project: project, sha: project.commit.id, ref: project.default_branch) }
+  let!(:pipeline) { create(:ci_empty_pipeline, project: project, sha: project.commit.id, ref: project.default_branch) }
   let!(:build) { create(:ci_build, pipeline: pipeline) }
 
   describe 'GET /projects/:id/builds ' do
@@ -174,7 +174,11 @@ describe API::API, api: true do
 
   describe 'GET /projects/:id/artifacts/:ref_name/download?job=name' do
     let(:api_user) { reporter.user }
-    let(:build) { create(:ci_build, :success, :artifacts, pipeline: pipeline) }
+    let(:build) { create(:ci_build, :artifacts, pipeline: pipeline) }
+
+    before do
+      build.success
+    end
 
     def path_for_ref(ref = pipeline.ref, job = build.name)
       api("/projects/#{project.id}/builds/artifacts/#{ref}/download?job=#{job}", api_user)
@@ -238,10 +242,6 @@ describe API::API, api: true do
         it { expect(response.headers).to include(download_headers) }
       end
 
-      before do
-        pipeline.reload_status!
-      end
-
       context 'with regular branch' do
         before do
           pipeline.update(ref: 'master',
diff --git a/spec/services/ci/image_for_build_service_spec.rb b/spec/services/ci/image_for_build_service_spec.rb
index 259062406c7..c931c3e4829 100644
--- a/spec/services/ci/image_for_build_service_spec.rb
+++ b/spec/services/ci/image_for_build_service_spec.rb
@@ -14,7 +14,6 @@ module Ci
       context 'branch name' do
         before { allow(project).to receive(:commit).and_return(OpenStruct.new(sha: commit_sha)) }
         before { build.run! }
-        before { pipeline.reload_status! }
         let(:image) { service.execute(project, ref: 'master') }
 
         it { expect(image).to be_kind_of(OpenStruct) }
@@ -32,7 +31,6 @@ module Ci
 
       context 'commit sha' do
         before { build.run! }
-        before { pipeline.reload_status! }
         let(:image) { service.execute(project, sha: build.sha) }
 
         it { expect(image).to be_kind_of(OpenStruct) }