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Class: ActiveSupport::StructuredEventSubscriber

Do not use. This class is for internal use only.

Overview

StructuredEventSubscriber consumes Notifications in order to emit structured events via Rails.event.

An example would be the Action Controller structured event subscriber, responsible for emitting request processing events:

module ActionController
  class StructuredEventSubscriber < ActiveSupport::StructuredEventSubscriber
    attach_to :action_controller

    def start_processing(event)
      emit_event("controller.request_started",
        controller: event.payload[:controller],
        action: event.payload[:action],
        format: event.payload[:format]
      )
    end
  end
end

After configured, whenever a "start_processing.action_controller" notification is published, it will properly dispatch the event (Notifications::Event) to the start_processing method. The subscriber can then emit a structured event via the #emit_event method.

Constant Summary

Class Attribute Summary

Subscriber - Inherited

.namespace, .notifier, .subscriber

Class Method Summary

Subscriber - Inherited

.attach_to

Attach the subscriber to a namespace.
.detach_from

Detach the subscriber from a namespace.
.method_added

Adds event subscribers for all new methods added to the class.
.new, .subscribers, .add_event_subscriber, .fetch_public_methods, .find_attached_subscriber, .invalid_event?, .pattern_subscribed?, .prepare_pattern, .remove_event_subscriber

Instance Attribute Summary

Subscriber - Inherited

#patterns

Instance Method Summary

Subscriber - Inherited

#call

Constructor Details

.new ⇒ StructuredEventSubscriber

[ GitHub ] 

  


# File 'activesupport/lib/active_support/structured_event_subscriber.rb', line 56



def initialize
  super
  @silenced_events = {}
end


  







Class Attribute Details



  

    .debug_methods   (rw)
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/structured_event_subscriber.rb', line 32



class_attribute :debug_methods, instance_accessor: false, default: [] # :nodoc:


  








  

    .debug_methods?  ⇒ Boolean  (rw)
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/structured_event_subscriber.rb', line 32



class_attribute :debug_methods, instance_accessor: false, default: [] # :nodoc:


  







Class Method Details



  

    .attach_to  
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/structured_event_subscriber.rb', line 37



def attach_to(...) # :nodoc:
  result = super
  set_silenced_events
  result
end


  








  

    .debug_only(method)   (private)
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/structured_event_subscriber.rb', line 50



def debug_only(method)
  self.debug_methods << method
  set_silenced_events
end


  








  

    .set_silenced_events   (private)
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/structured_event_subscriber.rb', line 44



def set_silenced_events
  if subscriber
    subscriber.silenced_events = debug_methods.to_h { |method| ["#{method}.#{namespace}", DEBUG_CHECK] }
  end
end


  







Instance Attribute Details



  

    #silenced_events=(value)   (writeonly)
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/structured_event_subscriber.rb', line 65



attr_writer :silenced_events # :nodoc:


  







Instance Method Details



  

    #call(event)  
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/structured_event_subscriber.rb', line 88



def call(event)
  super
rescue => e
  handle_event_error(event.name, e)
end


  








  

    #emit_debug_event(name, payload = nil, caller_depth: 1, **kwargs)  
  



  

    

Like #emit_event, but only emits when the event reporter is in debug mode


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/structured_event_subscriber.rb', line 82



def emit_debug_event(name, payload = nil, caller_depth: 1, **kwargs)
  ActiveSupport.event_reporter.debug(name, payload, caller_depth: caller_depth + 1, **kwargs)
rescue => e
  handle_event_error(name, e)
end


  








  

    #emit_event(name, payload = nil, caller_depth: 1, **kwargs)  
  



  

    

Emit a structured event via Rails.event.notify.



Arguments


  • 

    name - The event name as a string or symbol
    

  • 

    payload - The event payload as a hash or object
    

  • 

    caller_depth - Stack depth for source location (default: 1)
    

  • 

    kwargs - Additional payload data merged with the payload hash
    



  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/structured_event_subscriber.rb', line 75



def emit_event(name, payload = nil, caller_depth: 1, **kwargs)
  ActiveSupport.event_reporter.notify(name, payload, caller_depth: caller_depth + 1, **kwargs)
rescue => e
  handle_event_error(name, e)
end


  








  

    #handle_event_error(name, error)   (private)
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/structured_event_subscriber.rb', line 95



def handle_event_error(name, error)
  ActiveSupport.error_reporter.report(error, source: name)
end


  








  

    #silenced?(event)  ⇒ Boolean 
  



  

    
  





  


  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/structured_event_subscriber.rb', line 61



def silenced?(event)
  ActiveSupport.event_reporter.subscribers.none? || @silenced_events[event]&.call
end