Project	Resque::UniqueInQueue
gem name	resque-unique_in_queue
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Resque::UniqueInQueue is a resque plugin to add unique jobs to resque.

It is a re-write of resque_solo, which is a fork of resque-loner.

It requires resque 1.25 and works with ruby 2.0 and later.

It removes the dependency on Resque::Helpers, which is deprecated for resque 2.0.

Add the gem to your Gemfile:

gem 'resque-unique_in_queue'

resque-unique_in_queue utilizes 3 class instance variables that can be set in your Jobs, in addition to the standard @queue. Here they are, with their default values:

@lock_after_execution_period = 0
@ttl = -1
@unique_in_queue_key_base = 'r-uiq'.freeze

The last one, in normal circumstances, shouldn't be set as different per class, or uniqueness cleanup becomes more difficult.

It should be set only once, globally:

Resque::UniqueInQueue.configuration.unique_in_queue_key_base = 'my-custom'

class UpdateCat
  include Resque::Plugins::UniqueInQueue
  @queue = :cats
  def self.perform(cat_id)
    # do something
  end
end

If you attempt to queue a unique job multiple times, it is ignored:

Resque.enqueue UpdateCat, 1
=> true
Resque.enqueue UpdateCat, 1
=> nil
Resque.enqueue UpdateCat, 1
=> nil
Resque.size :cats
=> 1
Resque.enqueued? UpdateCat, 1
=> true
Resque.enqueued_in? :dogs, UpdateCat, 1
=> false

By default, lock_after_execution_period is 0 and enqueued? becomes false as soon as the job is being worked on.

The lock_after_execution_period setting can be used to delay when the unique job key is deleted (i.e. when enqueued? becomes false). For example, if you have a long-running unique job that takes around 10 seconds, and you don't want to requeue another job until you are sure it is done, you could set lock_after_execution_period = 20. Or if you never want to run a long running job more than once per minute, set lock_after_execution_period = 60.

class UpdateCat
  include Resque::Plugins::UniqueInQueue
  @queue = :cats
  @lock_after_execution_period = 20
  def self.perform(cat_id)
    # do something
  end
end

Preventing jobs with matching signatures from being queued, and they never get dequeued because there is no actual corresponding job to dequeue.

How to deal?

Option: Rampage

# Delete *all* queued jobs in the queue, and
#   delete *all* unqueness keys for the queue.
Redis.remove_queue('queue_name')

Option: Butterfly

# Delete *no* queued jobs at all, and
#   delete *all* unqueness keys for the queue (might then allow duplicates).
Resque::UniqueInQueue::Queue.cleanup('queue_name')

Bug reports and pull requests are welcome on GitHub at https://github.com/pboling/resque-unique_in_queue. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Added some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request

Everyone interacting in the Resque::Plugins::UniqueInQueue project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.

This library aims to adhere to Semantic Versioning 2.0.0. Violations of this scheme should be reported as bugs. Specifically, if a minor or patch version is released that breaks backward compatibility, a new version should be immediately released that restores compatibility. Breaking changes to the public API will only be introduced with new major versions.

As a result of this policy, you can (and should) specify a dependency on this gem using the Pessimistic Version Constraint with two digits of precision.

For example:

spec.add_dependency 'resque-unique_in_queue', '~> 1.0'

• Copyright (c) 2012 Jonathan R. Wallace
• Copyright (c) 2017 - 2018 Peter H. Boling of Rails Bling