Update and add documentation for job specific max_run_time

README.md

@@ -244,7 +244,9 @@ end
 
 Delayed::Job.enqueue NewsletterJob.new('lorem ipsum...', Customers.pluck(:email))
 ```
+
 To set a per-job max attempts that overrides the Delayed::Worker.max_attempts you can define a max_attempts method on the job
+
 ```ruby
 NewsletterJob = Struct.new(:text, :emails) do
   def perform
@@ -256,7 +258,25 @@ NewsletterJob = Struct.new(:text, :emails) do
   end
 end
 ```
+
+To set a per-job max run time that overrides the Delayed::Worker.max_run_time you can define a max_run_time method on the job
+
+NOTE: this can ONLY be used to set a max_run_time that is lower than Delayed::Worker.max_run_time. Otherwise the lock on the job would expire and another worker would start the working on the in progress job.
+
+```ruby
+NewsletterJob = Struct.new(:text, :emails) do
+  def perform
+    emails.each { |e| NewsletterMailer.deliver_text_to_email(text, e) }
+  end
+
+  def max_run_time
+    120 # seconds
+  end
+end
+```
+
 To set a default queue name for a custom job that overrides Delayed::Worker.default_queue_name, you can define a queue_name method on the job
+
 ```ruby
 NewsletterJob = Struct.new(:text, :emails) do
   def perform

lib/delayed/backend/base.rb

@@ -129,7 +129,14 @@ def max_attempts
       end
 
       def max_run_time
-        payload_object.max_run_time if payload_object.respond_to?(:max_run_time)
+        return unless payload_object.respond_to?(:max_run_time)
+        if (run_time = payload_object.max_run_time)
+          if run_time > Delayed::Worker.max_run_time
+            Delayed::Worker.max_run_time
+          else
+            run_time
+          end
+        end
       end
 
       def fail!

lib/delayed/backend/shared_spec.rb

@@ -435,6 +435,11 @@ def create_job(opts = {})
       expect(@job.payload_object).to receive(:max_run_time).and_return(45.minutes)
       expect(worker.max_run_time(@job)).to eq(45.minutes)
     end
+
+    it 'job set max_run_time can not exceed default max run time' do
+      expect(@job.payload_object).to receive(:max_run_time).and_return(Delayed::Worker::DEFAULT_MAX_RUN_TIME + 60)
+      expect(worker.max_run_time(@job)).to eq(Delayed::Worker::DEFAULT_MAX_RUN_TIME)
+    end
   end
 
   describe 'yaml serialization' do