Module: WideEvent::Subscribers

Defined in:
lib/wide_event/subscribers.rb

Overview

Copies measurements Rails already makes into the active wide event via ActiveSupport::Notifications. Subscribed once by the railtie.

Class Method Summary collapse

Class Method Details

.subscribe! ⇒ Object 



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# File 'lib/wide_event/subscribers.rb', line 5

def self.subscribe!
  return if @subscribed

  @subscribed = true

  ActiveSupport::Notifications.subscribe("process_action.action_controller") do |event|
    next unless WideEvent.active?

    payload = event.payload
    WideEvent.set("http.route.controller" => "#{payload[:controller]}##{payload[:action]}")
    WideEvent.set("db.duration_ms" => payload[:db_runtime].round(2)) if payload[:db_runtime]
    WideEvent.set("view.duration_ms" => payload[:view_runtime].round(2)) if payload[:view_runtime]
  rescue StandardError => e
    WideEvent.handle_error(e, "process_action")
  end

  ActiveSupport::Notifications.subscribe("cache_read.active_support") do |event|
    next unless WideEvent.active?

    prefix = event.payload[:key].to_s.split(%r{[/:]}).first.to_s.gsub(/[^a-z0-9_]+/i, "_")[0, 30].downcase
    next if prefix.empty?

    key = "cache.#{prefix}"
    attrs = WideEvent.peek
    # Cap distinct cache namespaces, but keep refreshing ones already
    # tracked: otherwise a prefix freezes at whatever value it had
    # when the cap-th distinct namespace appeared.
    next if !attrs.key?(key) && attrs.keys.count { |k| k.start_with?("cache.") } >= WideEvent.config.max_cache_attrs

    WideEvent.set(key => event.payload[:hit] ? true : false)
  rescue StandardError => e
    WideEvent.handle_error(e, "cache_read")
  end
end