Module: UniversalRenderer::Instrumentation

Defined in:
lib/universal_renderer/instrumentation.rb

Overview

Every SSR failure falls back to client-side rendering silently, which is right for availability and useless for operations. These two hooks are the signal that SSR stopped working.

Constant Summary collapse

NOTIFICATION =

ActiveSupport::Notifications event name. Subscribe to record hit rate and latency:

ActiveSupport::Notifications.subscribe("render.universal_renderer") do |event|
StatsD.timing("ssr.duration", event.duration, tags: ["outcome:#{event.payload[:outcome]}"])
end

Payload keys: :url, :mode (:blocking or :streaming), :outcome (:ok, :not_configured, :http_error, :timeout, or :error), and :status / :error where applicable.

"render.universal_renderer"

Class Method Summary collapse

Class Method Details

.instrument(url:, mode:) ⇒ Object

Instruments one render attempt. The block receives the mutable payload so it can record the outcome it reached.



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# File 'lib/universal_renderer/instrumentation.rb', line 24

def instrument(url:, mode:)
  payload = { url: url, mode: mode, outcome: :ok }

  ActiveSupport::Notifications.instrument(NOTIFICATION, payload) do
    yield payload
  end
end

.report(error, context) ⇒ Object

Hands an error to config.on_error, if one is configured. A raising callback must not turn a degraded render into a failed request.



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# File 'lib/universal_renderer/instrumentation.rb', line 34

def report(error, context)
  callback = UniversalRenderer.config.on_error
  return unless callback

  callback.call(error, context)
rescue StandardError => e
  UniversalRenderer.log do |log|
    log.error(
      "on_error callback raised: #{e.class.name} - #{e.message}"
    )
  end
end