Ariejan de Vroom – 16 March 2010
202 words in about 1 minute
Resque is a Redis-backed library for creating background jobs, placing those jobs on multiple queues, and processing them later. Sounds great! Let’s dive in directly:
1 2 3 4 5 6 7 8 9 10 class Archive @queue = :file_serve def self.perform(repo_id, branch = 'master') repo = Repository.find(repo_id) repo.create_archive(branch) end end Resque.enqueue(Archive, @repo.id)
This example was taken from the Resque README. It works great, but there’s a problem: you hard-code the queue to use. For an app I’m currently working on this is unwanted behaviour. So, how do you make Resque pick the right queue based on the data you feed it? In the following example I’ll show you how to pick the right queue based on the user that requests the job.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 class StreamWorker def self.enqueue(resource) Resque::Job.create(select_queue(resource), self, resource.id) end def self.select_queue(resource) resource.user.use_priority_queue? ? :stream_high : :stream_low end def self.perform(resource_id) resource = Resource.find_by_id(resource_id) return false if resource.nil? resource.process! end end
Instead of using Resque’s convenience method
Resque.enqueue we create a
Resque::Job ourselves. The
select_queue determines which queue is used. Creating a
StreamWorker job in the right queue is as easy as running:
In case you’re wondering, the
User#use_priority_queue? method returns a boolean based on the role the user has. Happy queueing!