Theoretical plugin API for Qu

option1.rb

# bts: If I'm writing a plugin, I'd typically like to have a namespace to add
# my own classes, so I would skip this option:

# Qu.plugin(:autoretry) do |*errors|
#   options = {:limit => 3}.merge!(errors.extract_options!)
#   errors << Exception if errors.empty?

#   before :failure do |job, e|
#     if errors.any? {|error| error === e }
#       job.data[:retries] += 1
#       Qu.requeue job unless job.config[:retries] >= limit
#       halt # don't report the error yet
#     end
#   end
# end

option2.rb

class Qu::Plugin::AutoRetry < Qu::Plugin
  # bts: forego the following line, and introspect plugin name from class via
  # underscoring the class' name
  #
  # plugin :autoretry

  # bts: use "acts" class methods instead of registering callbacks in
  # #initialize
  before_failure :retry
  before :failure, :retry

  attr_reader :errors, :options

  def initialize(*errors)
    @options = {:limit => 3}.merge!(errors.extract_options!)
    @errors << Exception if errors.empty?

    # bts: use class methods instead
    #
    # before :failure, :retry
  end

  def retry(job, e)
    if errors.any? {|error| error === e }
      job.data[:retries] += 1
      Qu.requeue job unless job.config[:retries] >= limit
      halt # don't report the error yet
    end
  end
end

usage.rb

class ProcessPresentation < Qu::Job
  # bts: use convention of underscored class name, so we don't have to
  # declare the plugin name twice in the Plugin (via class' name and also via
  # the "plugin :autoretry" declaration)
  #
  auto_retry Timeout::Error, :times => 5
  # autoretry Timeout::Error, :times => 5

  attr_reader :presentation

  def initialize(presentation_id)
    @presentation = Presentation.find(presentation)
  end

  def perform
    # …
  end
end