How can I check from my code if there's something enqueued in Sidekiq?

Question

When certain conditions are met, I'd like to schedule a worker to run a particular job in 5 minutes. The thing is, if the same conditions are met again, I want to check if there's something scheduled to run. If there is such a worker scheduled to run, then, I don't want to enqueue again, but if there isn't, it should be queued. I hope you guys understood what I'm trying to do. Can it be achieved? If yes, how?

Answer 1

Sounds like you want to use or implement a simple persisted lock. The code that enqueues the job can first check for the availability of the lock, acquire and enqueue if available, skip if not. The enqueued job can be responsible for releasing the lock. You'll want to account for failure, like adding a lock timeout. The redis-mutex gem may be a useful implementation of this idea.

Answer 2

Best practices promote jobs that are idempotent. This means that you should be writing them in such a way that it should be safe to run them more than once. Any subsequent call doesn't change the result of the first call. You achieve this by writing logic that does the proper checks, and acts accordingly. Since you don't provide a description of what your worker does, I can't be more specific.

For an example, here is a link to the Sidekiq's FAQ: Make your workers idempotent and transactional

The benefit of this approach is that you're playing along the convenient abstraction of scheduled workers, instead of fighting against it.