Check whether I am in a delayed_job process or not - ruby-on-rails

Question

I have a Rails app in which I use delayed_job. I want to detect whether I am in a delayed_job process or not; something like
if in_delayed_job?
# do something only if it is a delayed_job process...
else
# do something only if it is not a delayed_job process...
end
But I can't figure out how. This is what I'm using now:
IN_DELAYED_JOB = begin
basename = File.basename $0
arguments = $*
rake_args_regex = /\Ajobs:/
( basename == 'delayed_job' ) ||
( basename == 'rake' && arguments.find{ |v| v =~ rake_args_regex } )
end
Another solution is, as #MrDanA said:
$ DELAYED_JOB=true script/delayed_job start
# And in the app:
IN_DELAYED_JOB = ENV['DELAYED_JOB'].present?
but they are IMHO weak solutions. Can anyone suggest a better solution?

Answer 1

The way that I handle these is through a Paranoid worker. I use delayed_job for video transcoding that was uploaded to my site. Within the model of the video, I have a field called video_processing which is set to 0/null by default. Whenever the video is being transcoded by the delayed_job (whether on create or update of the video file), it will use the hooks from delayed_job and will update the video_processing whenever the job starts. Once the job is completed, the completed hook will update the field to 0.
In my view/controller I can do video.video_processing? ? "Video Transcoding in Progress" : "Video Fished Transcoding"

Answer 2

Maybe something like this. Add a field to your class and set it when your invoke the method that does all your work from delayed job:
class User < ActiveRecord::Base
attr_accessor :in_delayed_job
def queue_calculation_request
Delayed::Job.enqueue(CalculationRequest.new(self.id))
end
def do_the_work
if (in_delayed_job)
puts "Im in delayed job"
else
puts "I was called directly"
end
end
class CalculationRequest < Struct.new(:id)
def perform
user = User.find(id)
user.in_delayed_job = true
user.do_the_work
end
def display_name
"Perform the needeful user Calculations"
end
end
end
Here is how it looks:
From Delayed Job:
Worker(host:Johns-MacBook-Pro.local pid:67020)] Starting job worker
Im in delayed job
[Worker(host:Johns-MacBook-Pro.local pid:67020)] Perform the needeful user Calculations completed after 0.2787
[Worker(host:Johns-MacBook-Pro.local pid:67020)] 1 jobs processed at 1.5578 j/s, 0 failed ...
From the console
user = User.first.do_the_work
User Load (0.8ms) SELECT "users".* FROM "users" WHERE "users"."id" = $1 LIMIT 1 [["id", 101]]
I was called directly

Answer 3

This works for me:
def delayed_job_worker?
(ENV["_"].include? "delayed_job")
end
Unix will set the "_" environment variable to the current command.
It'll be wrong if you have a bin script called "not_a_delayed_job", but don't do that.

Answer 4

How about ENV['PROC_TYPE']
Speaking only of heroku... but when you're a worker dyno, this is set to 'worker'
I use it as my "I'm in a DJ"

Answer 5

You can create a plugin for delayed job, e.g. create the file is_dj_job_plugin.rb in the config/initializers directory.
class IsDjJobPlugin < Delayed::Plugin
callbacks do |lifecycle|
lifecycle.around(:invoke_job) do |job, *args, &block|
begin
old_is_dj_job = Thread.current[:is_dj_job]
Thread.current[:is_dj_job] = true
block.call(job, *args) # Forward the call to the next callback in the callback chain
Thread.current[:is_dj_job] = old_is_dj_job
end
end
end
def self.is_dj_job?
Thread.current[:is_dj_job] == true
end
end
Delayed::Worker.plugins << IsDjJobPlugin
You can then test in the following way:
class PrintDelayedStatus
def run
puts IsDjJobPlugin.is_dj_job? ? 'delayed' : 'not delayed'
end
end
PrintDelayedStatus.new.run
PrintDelayedStatus.new.delay.run