Class: Resque::Job

Inherits:
Object
  • Object
show all
Extended by:
Helpers
Includes:
Helpers
Defined in:
lib/resque/job.rb

Overview

A Resque::Job represents a unit of work. Each job lives on a single queue and has an associated payload object. The payload is a hash with two attributes: class and args. The class is the name of the Ruby class which should be used to run the job. The args are an array of arguments which should be passed to the Ruby class’s perform class-level method.

You can manually run a job using this code:

job = Resque::Job.reserve(:high)
klass = Resque::Job.constantize(job.payload['class'])
klass.perform(*job.payload['args'])

Constant Summary collapse

DontPerform =

Raise Resque::Job::DontPerform from a before_perform hook to abort the job.

Class.new(StandardError)

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(queue, payload) ⇒ Job

Returns a new instance of Job.



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# File 'lib/resque/job.rb', line 71

def initialize(queue, payload)
  @queue = queue
  @payload = payload
  @failure_hooks_ran = false
end

Instance Attribute Details

#payload ⇒ Object (readonly)

This job’s associated payload object.



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# File 'lib/resque/job.rb', line 69

def payload
  @payload
end

#queue ⇒ Object (readonly)

The name of the queue from which this job was pulled (or is to be placed)



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# File 'lib/resque/job.rb', line 66

def queue
  @queue
end

#worker ⇒ Object

The worker object which is currently processing this job.



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# File 'lib/resque/job.rb', line 62

def worker
  @worker
end

Class Method Details

.create(queue, klass, *args) ⇒ Object

Creates a job by placing it on a queue. Expects a string queue name, a string class name, and an optional array of arguments to pass to the class’ perform method.

Raises an exception if no queue or class is given.



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# File 'lib/resque/job.rb', line 82

def self.create(queue, klass, *args)
  Resque.validate(klass, queue)

  if Resque.inline?
    # Instantiating a Resque::Job and calling perform on it so callbacks run
    # decode(encode(args)) to ensure that args are normalized in the same manner as a non-inline job
    new(:inline, {'class' => klass, 'args' => decode(encode(args))}).perform
  else
    Resque.push(queue, :class => klass.to_s, :args => args)
  end
end

.decode(object) ⇒ Object

Given a string, returns a Ruby object.



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# File 'lib/resque/job.rb', line 43

def self.decode(object)
  Resque.decode(object)
end

.destroy(queue, klass, *args) ⇒ Object

Removes a job from a queue. Expects a string queue name, a string class name, and, optionally, args.

Returns the number of jobs destroyed.

If no args are provided, it will remove all jobs of the class provided.

That is, for these two jobs:

{ ‘class’ => ‘UpdateGraph’, ‘args’ => [‘defunkt’] } { ‘class’ => ‘UpdateGraph’, ‘args’ => [‘mojombo’] }

The following call will remove both:

Resque::Job.destroy(queue, 'UpdateGraph')

Whereas specifying args will only remove the 2nd job:

Resque::Job.destroy(queue, 'UpdateGraph', 'mojombo')

This method can be potentially very slow and memory intensive, depending on the size of your queue, as it loads all jobs into a Ruby array before processing.



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# File 'lib/resque/job.rb', line 118

def self.destroy(queue, klass, *args)
  klass = klass.to_s
  queue = "queue:#{queue}"
  destroyed = 0

  if args.empty?
    redis.lrange(queue, 0, -1).each do |string|
      if decode(string)['class'] == klass
        destroyed += redis.lrem(queue, 0, string).to_i
      end
    end
  else
    destroyed += redis.lrem(queue, 0, encode(:class => klass, :args => args))
  end

  destroyed
end

.encode(object) ⇒ Object

Given a Ruby object, returns a string suitable for storage in a queue.



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# File 'lib/resque/job.rb', line 38

def self.encode(object)
  Resque.encode(object)
end

.redis ⇒ Object 



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# File 'lib/resque/job.rb', line 21

def self.redis
  Resque.redis
end

.reserve(queue) ⇒ Object

Given a string queue name, returns an instance of Resque::Job if any jobs are available. If not, returns nil.



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# File 'lib/resque/job.rb', line 138

def self.reserve(queue)
  return unless payload = Resque.pop(queue)
  new(queue, payload)
end

Instance Method Details

#==(other) ⇒ Object

Equality



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# File 'lib/resque/job.rb', line 255

def ==(other)
  queue == other.queue &&
    payload_class == other.payload_class &&
    args == other.args
end

#after_hooks ⇒ Object 



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# File 'lib/resque/job.rb', line 269

def after_hooks
  @after_hooks ||= Plugin.after_hooks(payload_class)
end

#args ⇒ Object

Returns an array of args represented in this job’s payload.



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# File 'lib/resque/job.rb', line 222

def args
  @payload['args']
end

#around_hooks ⇒ Object 



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# File 'lib/resque/job.rb', line 265

def around_hooks
  @around_hooks ||= Plugin.around_hooks(payload_class)
end

#before_hooks ⇒ Object 



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# File 'lib/resque/job.rb', line 261

def before_hooks
  @before_hooks ||= Plugin.before_hooks(payload_class)
end

#classify(dashed_word) ⇒ Object

Given a word with dashes, returns a camel cased version of it.



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# File 'lib/resque/job.rb', line 48

def classify(dashed_word)
  Resque.classify(dashed_word)
end

#constantize(camel_cased_word) ⇒ Object

Tries to find a constant with the name specified in the argument string



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# File 'lib/resque/job.rb', line 53

def constantize(camel_cased_word)
  Resque.constantize(camel_cased_word)
end

#decode(object) ⇒ Object

Given a string, returns a Ruby object.



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# File 'lib/resque/job.rb', line 32

def decode(object)
  Resque.decode(object)
end

#encode(object) ⇒ Object

Given a Ruby object, returns a string suitable for storage in a queue.



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# File 'lib/resque/job.rb', line 27

def encode(object)
  Resque.encode(object)
end

#fail(exception) ⇒ Object

Given an exception object, hands off the needed parameters to the Failure module.



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# File 'lib/resque/job.rb', line 228

def fail(exception)
  begin
    run_failure_hooks(exception)
  rescue Exception => e
    raise e
  ensure
    Failure.create \
      :payload   => payload,
      :exception => exception,
      :worker    => worker,
      :queue     => queue
  end
end

#failure_hooks ⇒ Object 



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# File 'lib/resque/job.rb', line 273

def failure_hooks
  @failure_hooks ||= Plugin.failure_hooks(payload_class)
end

#has_payload_class? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/resque/job.rb', line 215

def has_payload_class?
  payload_class != Object
rescue NameError
  false
end

#inspect ⇒ Object

String representation



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# File 'lib/resque/job.rb', line 249

def inspect
  obj = @payload
  "(Job{%s} | %s | %s)" % [ @queue, obj['class'], obj['args'].inspect ]
end

#payload_class ⇒ Object

Returns the actual class constant represented in this job’s payload.



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# File 'lib/resque/job.rb', line 204

def payload_class
  @payload_class ||= constantize(@payload['class'])
end

#payload_class_name ⇒ Object

Returns the payload class as a string without raising NameError



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# File 'lib/resque/job.rb', line 209

def payload_class_name
  payload_class.to_s
rescue NameError
  'No Name'
end

#perform ⇒ Object

Attempts to perform the work represented by this job instance. Calls #perform on the class given in the payload with the arguments given in the payload.



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# File 'lib/resque/job.rb', line 146

def perform
  job = payload_class
  job_args = args || []
  job_was_performed = false

  begin
    # Execute before_perform hook. Abort the job gracefully if
    # Resque::DontPerform is raised.
    begin
      before_hooks.each do |hook|
        job.send(hook, *job_args)
      end
    rescue DontPerform
      return false
    end

    # Execute the job. Do it in an around_perform hook if available.
    if around_hooks.empty?
      job.perform(*job_args)
      job_was_performed = true
    else
      # We want to nest all around_perform plugins, with the last one
      # finally calling perform
      stack = around_hooks.reverse.inject(nil) do |last_hook, hook|
        if last_hook
          lambda do
            job.send(hook, *job_args) { last_hook.call }
          end
        else
          lambda do
            job.send(hook, *job_args) do
              result = job.perform(*job_args)
              job_was_performed = true
              result
            end
          end
        end
      end
      stack.call
    end

    # Execute after_perform hook
    after_hooks.each do |hook|
      job.send(hook, *job_args)
    end

    # Return true if the job was performed
    return job_was_performed

  # If an exception occurs during the job execution, look for an
  # on_failure hook then re-raise.
  rescue Object => e
    run_failure_hooks(e)
    raise e
  end
end

#recreate ⇒ Object

Creates an identical job, essentially placing this job back on the queue.



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# File 'lib/resque/job.rb', line 244

def recreate
  self.class.create(queue, payload_class, *args)
end

#redis ⇒ Object 



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# File 'lib/resque/job.rb', line 17

def redis
  Resque.redis
end

#run_failure_hooks(exception) ⇒ Object 



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# File 'lib/resque/job.rb', line 277

def run_failure_hooks(exception)
  begin
    job_args = args || []
    if has_payload_class?
      failure_hooks.each { |hook| payload_class.send(hook, exception, *job_args) } unless @failure_hooks_ran
    end
  rescue Exception => e
    error_message = "Additional error (#{e.class}: #{e}) occurred in running failure hooks for job #{inspect}\n" \
                    "Original error that caused job failure was #{e.class}: #{exception.class}: #{exception.message}"
    raise RuntimeError.new(error_message)
  ensure
    @failure_hooks_ran = true
  end
end