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Class: ActionDispatch::ServerTiming

Relationships & Source Files
Namespace Children
Classes:
Subscriber
Inherits: Object
Defined in: actionpack/lib/action_dispatch/middleware/server_timing.rb

Class Method Summary

Instance Method Summary

Constructor Details

.new(app) ⇒ ServerTiming

[ GitHub ] 

  


# File 'actionpack/lib/action_dispatch/middleware/server_timing.rb', line 52



def initialize(app)
  @app = app
  @subscriber = Subscriber.instance
  @subscriber.ensure_subscribed
end


  







Class Method Details



  

    .unsubscribe  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'actionpack/lib/action_dispatch/middleware/server_timing.rb', line 48



def self.unsubscribe # :nodoc:
  Subscriber.instance.unsubscribe
end


  







Instance Method Details



  

    #call(env)  
  

  [ GitHub ]


  

  


# File 'actionpack/lib/action_dispatch/middleware/server_timing.rb', line 58



def call(env)
  response = nil
  events = @subscriber.collect_events do
    response = @app.call(env)
  end

  headers = response[1]

  header_info = events.group_by(&:name).map do |event_name, events_collection|
    "%s;dur=%.2f" % [event_name, exclusive_duration_sum(events_collection)]
  end

  if headers[ActionDispatch::Constants::SERVER_TIMING].present?
    header_info.prepend(headers[ActionDispatch::Constants::SERVER_TIMING])
  end
  headers[ActionDispatch::Constants::SERVER_TIMING] = header_info.join(", ")

  response
end


  








  

    #exclusive_duration_sum(events)   (private)
  



  

    
Sum durations for one event name without double-counting nested events.
Nested notifications (e.g. a partial that renders another partial) report
inclusive durations; subtracting direct same-name children yields exclusive
time so the metric stays within wall-clock bounds.

  



  [ GitHub ]


  

  


# File 'actionpack/lib/action_dispatch/middleware/server_timing.rb', line 83



def exclusive_duration_sum(events)
  return 0.0 if events.empty?
  return events.first.duration if events.one?

  sorted = events.sort_by { |event| [event.time, -event.duration] }
  children_ms = Hash.new(0.0)
  stack = []

  sorted.each do |event|
    while stack.any? && stack.last.end <= event.time
      stack.pop
    end

    if stack.any? && event.end <= stack.last.end
      children_ms[stack.last] += event.duration
    end

    stack << event
  end

  events.sum { |event| event.duration - children_ms[event] }
end