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

Methods included from Helpers

classify, constantize, decode, encode, redis

Constructor Details

#initialize(queue, payload) ⇒ Job

Returns a new instance of Job


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

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

Instance Attribute Details

#payloadObject (readonly)

This job's associated payload object.


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# File 'lib/resque/job.rb', line 30

def payload
  @payload
end

#queueObject (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 27

def queue
  @queue
end

#workerObject

The worker object which is currently processing this job.


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# File 'lib/resque/job.rb', line 23

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 42

def self.create(queue, klass, *args)
  if !queue
    raise NoQueueError.new("Jobs must be placed onto a queue.")
  end

  if klass.to_s.empty?
    raise NoClassError.new("Jobs must be given a class.")
  end

  Resque.push(queue, :class => klass.to_s, :args => args)
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 78

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

  redis.lrange(queue, 0, -1).each do |string|
    json   = decode(string)

    match  = json['class'] == klass
    match &= json['args'] == args unless args.empty?

    if match
      destroyed += redis.lrem(queue, 0, string).to_i
    end
  end

  destroyed
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 99

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 202

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

#argsObject

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


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# File 'lib/resque/job.rb', line 175

def args
  @payload['args']
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 181

def fail(exception)
  Failure.create \
    :payload   => payload,
    :exception => exception,
    :worker    => worker,
    :queue     => queue
end

#inspectObject

String representation


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# File 'lib/resque/job.rb', line 196

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

#payload_classObject

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


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# File 'lib/resque/job.rb', line 170

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

#performObject

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 107

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

  before_hooks  = Plugin.before_hooks(job)
  around_hooks  = Plugin.around_hooks(job)
  after_hooks   = Plugin.after_hooks(job)
  failure_hooks = Plugin.failure_hooks(job)

  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
    failure_hooks.each { |hook| job.send(hook, e, *job_args) }
    raise e
  end
end

#recreateObject

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


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# File 'lib/resque/job.rb', line 191

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