Resque Lock

A Resque plugin. Requires Resque 1.7.0.

If you want only one instance of your job queued at a time, extend it with this module.

For example:

require 'resque/plugins/lock'

class UpdateNetworkGraph
  extend Resque::Plugins::Lock

  def self.perform(repo_id)
    heavy_lifting
  end
end

While this job is queued or running, no other UpdateNetworkGraph jobs with the same arguments will be placed on the queue.

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
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.

It is also possible to define locks which will get released BEFORE performing a job by overriding the lock_running? class method in your subclass. This is useful in cases where you need to get a job queued even if another job on same queue is already running, e.g.

class UpdateNetworkGraph
  extend Resque::Plugins::Lock

  # Do not lock a running job
  def self.lock_running?
    false
  end
end