Class: ActiveSupport::StructuredEventSubscriber

Inherits:
Subscriber show all
Defined in:
lib/active_support/structured_event_subscriber.rb

Overview

Active Support Structured Event Subscriber

ActiveSupport::StructuredEventSubscriber consumes ActiveSupport::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 (ActiveSupport::Notifications::Event) to the start_processing method. The subscriber can then emit a structured event via the emit_event method.

Constant Summary collapse

DEBUG_CHECK = 
proc { !ActiveSupport.event_reporter.debug_mode? }

Instance Attribute Summary collapse

Attributes inherited from Subscriber

#patterns

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Subscriber

detach_from, method_added, subscribers

Constructor Details

#initialize ⇒ StructuredEventSubscriber

Returns a new instance of StructuredEventSubscriber.



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

def initialize
  super
  @silenced_events = {}
end

Instance Attribute Details

#silenced_events=(value) ⇒ Object (writeonly)

:nodoc:



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

def silenced_events=(value)
  @silenced_events = value
end

Class Method Details

.attach_to ⇒ Object

:nodoc:



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

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

Instance Method Details

#call(event) ⇒ Object 



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# File '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) ⇒ Object

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



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# File '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) ⇒ Object

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



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# File '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

#silenced?(event) ⇒ Boolean

Returns:

  • (Boolean) 


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

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