Add ability to control the dequeue #421
Merged
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Problem
Currently, Exq provides concurrency control per queue per worker node. But if anyone wants to rate limit based on different factors, it's not possible to do unless via middleware. The problem with going via middleware is, the job is already dequeued at that point and the only way to stop further dequeue is via
unsubscribe
API. The unsubscribe API is async, so we can't control the exact number of jobs dequeued via it.Proposal
Add the ability to control dequeue operation via a new Behaviour. Exq will provide a default implementation and others can override the default implementation per queue.
POC
I have been working on a POC exq_limit to validate the API. I will try to test it in the coming weeks.
refer #178