Using delayed job I want to modify reschedule_at based on error message

Question

Using the error, failure and reschedule_at callbacks is there a way to make reschedule_at time depend on what type of error i receive?

I have set the reschedule_at method but if affects all jobs of this type. I don't know where to handle this behavior based on error type and in what handler.

Answer 1

After some testing it seems that you can do custom rescheduling based on the particular job error message with the following approach:

1. Define an instance variable in the job to hold the custom retry delay. This variable will get serialized to the database (or any other DelayedJob backend) among all other variables, i.e. its state will be preserved between job runs.

2. In the error hook, set the delay to any value based on the error that you'll get in the exception parameter (which is an Exception object).

3. Use that custom delay in the reschedule_at method.

The solution leverages the fact that the reschedule_at method is called after the error hook. See the following example:

class MyJob

  attr_accessor :retry_delay

  def initialize
    self.retry_delay = 5 # default retry delay
  end

  def error(job, exception)
    # set up a different the delay time on a specific error
    if exception.is_a? NameError
      self.retry_delay = 10
    end
  end

  def reschedule_at(current_time, attempts)
    current_time + retry_delay.seconds
  end

end