track meta data with resque jobs, like when it was queued.

gistfile1.rb

module Resque
  def push_with_meta(queue, item)
    if item.respond_to?(:[]=)
      item[:meta] = {:queued_at => Time.now.to_f}
    end
    push_without_meta(queue, item)
  end

  class Job
    # Returns a Hash of the meta data related to this Job.
    def metadata
      @metadata ||= payload['meta'] || {}
    end

    # Returns the Time that this Job was queued, or nil.
    def queued_at
      @queued_at ||= metadata.key?('queued_at') ? Time.at(metadata['queued_at']) : nil
    end

    # Ugly way of wrapping around #perform.  Resque has a before_perform hook,
    # but it only passes the arguments instead of the job object.  There's no
    # other way to get to the job metadata.
    def perform_with_metrics
      if ts = queued_at
        ActiveSupport::Notifications.publish("queued.resque",
          ts, Time.now, SecureRandom.hex(10),
          :queue => queue, :class => self.class.name)
      end

      perform_without_metrics
    end

    alias perform_without_metrics perform
    alias perform perform_with_metrics
  end
end

# Doing this in the model affected the module's instance methods, even though
# they're used like class methods because of `extend self`.
class << Resque
  alias push_without_meta push
  alias push push_with_meta
end