Add class that handles pipeline creation sequence

app/services/ci/create_pipeline_service.rb

@@ -20,25 +20,20 @@ module Ci
         protected: project.protected_for?(ref)
       )
 
-      @pipeline.tap do |pipeline|
-        command = OpenStruct.new(ignore_skip_ci: ignore_skip_ci,
-                                 save_incompleted: save_on_errors,
-                                 trigger_request: trigger_request,
-                                 schedule: schedule,
-                                 seeds_block: block,
-                                 project: project,
-                                 current_user: current_user)
-
-        sequence = SEQUENCE.map { |chain| chain.new(pipeline, command) }
-
-        sequence_complete = sequence.none? do |chain|
-          chain.perform!
-          chain.break?
-        end
+      command = OpenStruct.new(ignore_skip_ci: ignore_skip_ci,
+                               save_incompleted: save_on_errors,
+                               seeds_block: block,
+                               project: project,
+                               current_user: current_user)
+
+
+      sequence = Gitlab::Ci::Pipeline::Chain::Sequence
+        .new(pipeline, command, SEQUENCE)
 
+      sequence.build! do |pipeline, sequence|
         update_merge_requests_head_pipeline if pipeline.persisted?
 
-        if sequence_complete
+        if sequence.complete?
           cancel_pending_pipelines if project.auto_cancel_pending_pipelines?
           pipeline_created_counter.increment(source: source)
 
@@ -49,6 +44,9 @@ module Ci
 
     private
 
+    def process_pipeline_sequence
+    end
+
     def commit
       @commit ||= project.commit(origin_sha || origin_ref)
     end

lib/gitlab/ci/pipeline/chain/sequence.rb

+module Gitlab
+  module Ci
+    module Pipeline
+      module Chain
+        class Sequence
+          def initialize(pipeline, command, sequence)
+            @pipeline = pipeline
+            @completed = []
+
+            @sequence = sequence.map do |chain|
+              chain.new(pipeline, command)
+            end
+          end
+
+          def build!
+           @sequence.each do |step|
+              step.perform!
+
+              break if step.break?
+
+              @completed << true
+            end
+
+            @pipeline.tap do
+              yield @pipeline, self if block_given?
+            end
+          end
+
+          def complete?
+            @completed.size == @sequence.size &&
+              @completed.all?
+          end
+        end
+      end
+    end
+  end
+end