Add lock-related scopes to ActiveRecord backend (#41)

Author: westonkd

lib/delayed/backend/active_record.rb

@@ -28,6 +28,9 @@ class Job < AbstractJob
         attr_accessor :enqueue_result
 
         scope :next_in_strand_order, -> { order(:strand_order_override, :id) }
+        scope :locked, -> { where.not(locked_by: nil) }
+        scope :not_locked, -> { where(locked_by: nil) }
+        scope :prefetched, -> { where(arel_table[:locked_by].matches("prefetch%")) }
 
         def self.reconnect!
           ::ActiveRecord::Base.connection_handler.clear_all_connections!(nil)

spec/active_record_job_spec.rb

@@ -11,6 +11,45 @@
 
   include_examples "a delayed_jobs implementation"
 
+  describe ".locked" do
+    subject(:locked_jobs) { Delayed::Job.locked }
+
+    let!(:not_locked_job) { Delayed::Job.create(payload_object: SimpleJob.new) }
+    let!(:locked_job) { Delayed::Job.create(payload_object: SimpleJob.new) }
+
+    before { locked_job.send(:lock_exclusively!, "worker-123") }
+
+    it "only includes locked jobs" do
+      expect(locked_jobs).to eq [locked_job]
+    end
+  end
+
+  describe ".not_locked" do
+    subject(:not_locked_jobs) { Delayed::Job.not_locked }
+
+    let!(:not_locked_job) { Delayed::Job.create(payload_object: SimpleJob.new) }
+    let!(:locked_job) { Delayed::Job.create(payload_object: SimpleJob.new) }
+
+    before { locked_job.send(:lock_exclusively!, "worker-123") }
+
+    it "only includes not locked jobs" do
+      expect(not_locked_jobs).to eq [not_locked_job]
+    end
+  end
+
+  describe ".prefetched" do
+    subject(:prefetched_jobs) { Delayed::Job.prefetched }
+
+    let!(:not_prefetched_job) { Delayed::Job.create(payload_object: SimpleJob.new) }
+    let!(:prefetched_job) { Delayed::Job.create(payload_object: SimpleJob.new) }
+
+    before { prefetched_job.update!(locked_by: "prefetch:worker-123") }
+
+    it "only includes prefetched jobs" do
+      expect(prefetched_jobs).to eq [prefetched_job]
+    end
+  end
+
   it "recovers as well as possible from a failure failing a job" do
     allow(Delayed::Job::Failed).to receive(:create).and_raise(RuntimeError)
     job = "test".delay(ignore_transaction: true).reverse