Class: GoodJob::Performer

Inherits:
Object
  • Object
show all
Defined in:
lib/good_job/performer.rb

Overview

Performer queries the database for jobs and performs them on behalf of a Scheduler. It mainly functions as glue between a Scheduler and the jobs it should be executing.

The Performer enforces a callable that does not rely on scoped/closure variables because they might not be available when executed in a different thread.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(target, method_name, name: nil, filter: nil) ⇒ Performer

Returns a new instance of Performer.

Parameters:

  • target (Object) —

    An object that can perform jobs. It must respond to method_name by finding and performing jobs and is usually a Job query, e.g. GoodJob::Job.where(queue_name: [‘queue1’, ‘queue2’]).

  • method_name (Symbol) —

    The name of a method on target that finds and performs jobs.

  • name (String) (defaults to: nil) —

    A name for the performer to be used in logs and for debugging.

  • filter (#call) (defaults to: nil) —

    Used to determine whether the performer should be used in GoodJob’s current state. GoodJob state is a Hash that will be passed as the first argument to filter and includes info like the current queue.



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# File 'lib/good_job/performer.rb', line 31

def initialize(target, method_name, name: nil, filter: nil)
  @target = target
  @method_name = method_name
  @name = name
  @filter = filter
end

Instance Attribute Details

#name ⇒ String (readonly)

Returns a meaningful name to identify the performer in logs and for debugging. This is usually set to the list of queues the performer will query, e.g. “-transactional_messages,batch_processing”.

Returns:

  • (String) —

    a meaningful name to identify the performer in logs and for debugging. This is usually set to the list of queues the performer will query, e.g. “-transactional_messages,batch_processing”.



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# File 'lib/good_job/performer.rb', line 17

def name
  @name
end

Instance Method Details

#next ⇒ Object

Find and perform any eligible jobs.



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# File 'lib/good_job/performer.rb', line 39

def next
  @target.public_send(@method_name)
end

#next?(state = {}) ⇒ Boolean

Tests whether this performer should be used in GoodJob’s current state by calling the filter callable set in #initialize. Always returns true if there is no filter.

For example, state will be a LISTEN/NOTIFY message that is passed down from the Notifier to the Scheduler. The Scheduler is able to ask its performer “does this message relate to you?”, and if not, ignore it to minimize thread wake-ups, database queries, and thundering herds.

Returns:

  • (Boolean) —

    whether the performer’s #next method should be called in the current state.



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# File 'lib/good_job/performer.rb', line 54

def next?(state = {})
  return true unless @filter.respond_to?(:call)

  @filter.call(state)
end