Added filtering jobs by age to jobs/request API endpoint

app/models/ci/build.rb

@@ -140,6 +140,8 @@ module Ci
       where("EXISTS (?)", matcher)
     end
+    scope :queued_before, ->(time) { where(arel_table[:queued_at].lt(time)) }
+
     ##
     # TODO: Remove these mounters when we remove :ci_enable_legacy_artifacts feature flag
     mount_uploader :legacy_artifacts_file, LegacyArtifactUploader, mount_on: :artifacts_file

app/services/ci/register_job_service.rb

@@ -36,6 +36,11 @@ module Ci
         builds = builds.with_any_tags
       end
+      # pick builds that older than specified age
+      if params.key?(:job_age)
+        builds = builds.queued_before(params[:job_age].seconds.ago)
+      end
+
       builds.each do |build|
         next unless runner.can_pick?(build)

changelogs/unreleased/1340-request-job-with-age.yml

+---
+title: "Added option to filter jobs by age in the /job/request API endpoint."
+merge_request: 1340
+author: Dmitry Chepurovskiy
+type: added

db/migrate/20190516011213_add_build_queued_at_index.rb

+# frozen_string_literal: true
+
+# This migration make queued_at field indexed to speed up builds filtering by job_age
+
+class AddBuildQueuedAtIndex < ActiveRecord::Migration[5.1]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_index :ci_builds, :queued_at
+  end
+
+  def down
+    remove_concurrent_index :ci_builds, :queued_at
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
-ActiveRecord::Schema.define(version: 20190515125613) do
+ActiveRecord::Schema.define(version: 20190516011213) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -380,6 +380,7 @@ ActiveRecord::Schema.define(version: 20190515125613) do
     t.index ["project_id", "id"], name: "index_ci_builds_on_project_id_and_id", using: :btree
     t.index ["project_id", "status"], name: "index_ci_builds_project_id_and_status_for_live_jobs_partial2", where: "(((type)::text = 'Ci::Build'::text) AND ((status)::text = ANY (ARRAY[('running'::character varying)::text, ('pending'::character varying)::text, ('created'::character varying)::text])))", using: :btree
     t.index ["protected"], name: "index_ci_builds_on_protected", using: :btree
+    t.index ["queued_at"], name: "index_ci_builds_on_queued_at", using: :btree
     t.index ["runner_id"], name: "index_ci_builds_on_runner_id", using: :btree
     t.index ["scheduled_at"], name: "partial_index_ci_builds_on_scheduled_at_with_scheduled_jobs", where: "((scheduled_at IS NOT NULL) AND ((type)::text = 'Ci::Build'::text) AND ((status)::text = 'scheduled'::text))", using: :btree
     t.index ["stage_id", "stage_idx"], name: "tmp_build_stage_position_index", where: "(stage_idx IS NOT NULL)", using: :btree

lib/api/runner.rb

@@ -98,6 +98,7 @@ module API
           optional :certificate, type: String, desc: %q(Session's certificate)
           optional :authorization, type: String, desc: %q(Session's authorization)
         end
+        optional :job_age, type: Integer, desc: %q(Job should be older than passed age in seconds to be ran on runner)
       end
       post '/request' do
         authenticate_runner!

spec/requests/api/runner_spec.rb

@@ -542,6 +542,30 @@ describe API::Runner, :clean_gitlab_redis_shared_state do
             end
           end
+          context 'when job filtered by job_age' do
+            let!(:job) { create(:ci_build, :tag, pipeline: pipeline, name: 'spinach', stage: 'test', stage_idx: 0, queued_at: 60.seconds.ago) }
+
+            context 'job is queued less than job_age parameter' do
+              let(:job_age) { 120 }
+
+              it 'gives 204' do
+                request_job(job_age: job_age)
+
+                expect(response).to have_gitlab_http_status(204)
+              end
+            end
+
+            context 'job is queued more than job_age parameter' do
+              let(:job_age) { 30 }
+
+              it 'picks a job' do
+                request_job(job_age: job_age)
+
+                expect(response).to have_gitlab_http_status(201)
+              end
+            end
+          end
+
           context 'when job is made for branch' do
             it 'sets tag as ref_type' do
               request_job