GAV1N/resque-lock-with-callback

A fork of the resque-lock plugin that will execute a callback if a job is skipped due to a lock.

Resque Lock With Callback

A Resque plugin. Requires Resque 1.7.0.

If you want only one instance of your job queued at a time, and want to be be able to run a callback when a duplicate job tries to run while the lock is in effect, extend it with this module.

For example:

class UpdateNetworkGraph
  extend Resque::Jobs::LockWithCallback

  def self.perform(repo_id)
    heavy_lifting
  end

  def self.job_locked(repo_id)
    # Some handler for when a job is locked
    # and another job with the same lock key
    # tries to execute. For example:
    Resque.enqueue self, repo_id
  end

end

While this job is queued or running, no other UpdateNetworkGraph jobs with the same arguments will be placed on the queue. The job_locked callback will be called, allowing you to handle future UpdateNetworkGraph jobs that run while the lock is in effect, rather than those jobs just being skipped.

If you want to define the key yourself you can override the lock class method in your subclass, e.g.

class UpdateNetworkGraph
  extend Resque::Plugins::Lock

  Run only one at a time, regardless of repo_id.
  def self.lock(repo_id)
    "network-graph"
  end

  def self.perform(repo_id)
    heavy_lifting
  end
  
  def self.job_locked(repo_id)
    # Some handler for when a job is locked
    # and another job with the same lock key
    # tries to execute. For example:
    Resque.enqueue self, repo_id
  end

end

The above modification will ensure only one job of class UpdateNetworkGraph is queued at a time, regardless of the repo_id. Normally a job is locked using a combination of its class name and arguments.