Add support for DAG

This implements the support for `needs:` keyword
as part of GitLab CI. That makes some of the jobs
to be run out of order.

5 files changed, 39 insertions, 6 deletions

diff --git a/app/models/ci/build.rb b/app/models/ci/build.rb
index 07813e03f3a..dd2bfc42af9 100644
--- a/app/models/ci/build.rb
+++ b/app/models/ci/build.rb
@@ -38,6 +38,7 @@ module Ci
     has_one :deployment, as: :deployable, class_name: 'Deployment'
     has_many :trace_sections, class_name: 'Ci::BuildTraceSection'
     has_many :trace_chunks, class_name: 'Ci::BuildTraceChunk', foreign_key: :build_id
+    has_many :needs, class_name: 'Ci::BuildNeed', foreign_key: :build_id, inverse_of: :build
 
     has_many :job_artifacts, class_name: 'Ci::JobArtifact', foreign_key: :job_id, dependent: :destroy, inverse_of: :job # rubocop:disable Cop/ActiveRecordDependent
     has_many :job_variables, class_name: 'Ci::JobVariable', foreign_key: :job_id
@@ -50,6 +51,7 @@ module Ci
 
     accepts_nested_attributes_for :runner_session
     accepts_nested_attributes_for :job_variables
+    accepts_nested_attributes_for :needs
 
     delegate :url, to: :runner_session, prefix: true, allow_nil: true
     delegate :terminal_specification, to: :runner_session, allow_nil: true
@@ -713,11 +715,21 @@ module Ci
 
       depended_jobs = depends_on_builds
 
-      return depended_jobs unless options[:dependencies].present?
+      # find all jobs that are dependent on
+      if options[:dependencies].present?
+        depended_jobs = depended_jobs.select do |job|
+          options[:dependencies].include?(job.name)
+        end
+      end
 
-      depended_jobs.select do |job|
-        options[:dependencies].include?(job.name)
+      # find all jobs that are needed by this one
+      if options[:needs].present?
+        depended_jobs = depended_jobs.select do |job|
+          options[:needs].include?(job.name)
+        end
       end
+
+      depended_jobs
     end
 
     def empty_dependencies?
diff --git a/app/models/ci/build_need.rb b/app/models/ci/build_need.rb
new file mode 100644
index 00000000000..6531dfd332f
--- /dev/null
+++ b/app/models/ci/build_need.rb
@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+module Ci
+  class BuildNeed < ApplicationRecord
+    extend Gitlab::Ci::Model
+
+    belongs_to :build, class_name: "Ci::Build", foreign_key: :build_id, inverse_of: :needs
+
+    validates :build, presence: true
+    validates :name, presence: true, length: { maximum: 128 }
+
+    scope :scoped_build, -> { where('ci_builds.id=ci_build_needs.build_id') }
+  end
+end
diff --git a/app/models/ci/pipeline.rb b/app/models/ci/pipeline.rb
index 1c76f401690..3515f0b83ee 100644
--- a/app/models/ci/pipeline.rb
+++ b/app/models/ci/pipeline.rb
@@ -611,8 +611,8 @@ module Ci
     end
 
     # rubocop: disable CodeReuse/ServiceClass
-    def process!
-      Ci::ProcessPipelineService.new(project, user).execute(self)
+    def process!(trigger_build_name = nil)
+      Ci::ProcessPipelineService.new(project, user).execute(self, trigger_build_name)
     end
     # rubocop: enable CodeReuse/ServiceClass
 
diff --git a/app/models/commit_status.rb b/app/models/commit_status.rb
index be6f3e9c5b0..d7eb78db5b8 100644
--- a/app/models/commit_status.rb
+++ b/app/models/commit_status.rb
@@ -43,6 +43,12 @@ class CommitStatus < ApplicationRecord
   scope :after_stage, -> (index) { where('stage_idx > ?', index) }
   scope :processables, -> { where(type: %w[Ci::Build Ci::Bridge]) }
 
+  scope :with_needs, -> (names = nil) do
+    needs = Ci::BuildNeed.scoped_build.select(1)
+    needs = needs.where(name: names) if names
+    where('EXISTS (?)', needs).preload(:needs)
+  end
+
   # We use `CommitStatusEnums.failure_reasons` here so that EE can more easily
   # extend this `Hash` with new values.
   enum_with_nil failure_reason: ::CommitStatusEnums.failure_reasons
@@ -116,7 +122,7 @@ class CommitStatus < ApplicationRecord
       commit_status.run_after_commit do
         if pipeline_id
           if complete? || manual?
-            PipelineProcessWorker.perform_async(pipeline_id)
+            BuildProcessWorker.perform_async(id)
           else
             PipelineUpdateWorker.perform_async(pipeline_id)
           end
diff --git a/app/models/concerns/ci/metadatable.rb b/app/models/concerns/ci/metadatable.rb
index 9eed9492b37..304cc71e9dc 100644
--- a/app/models/concerns/ci/metadatable.rb
+++ b/app/models/concerns/ci/metadatable.rb
@@ -29,6 +29,7 @@ module Ci
     def degenerate!
       self.class.transaction do
         self.update!(options: nil, yaml_variables: nil)
+        self.needs.all.delete_all
         self.metadata&.destroy
       end
     end