Module: Datadog::Contrib::ActionView::Instrumentation::TemplateRenderer::Rails30

Defined in:
lib/ddtrace/contrib/action_view/instrumentation/template_renderer.rb

Overview

Rails < 3.1 template rendering

Class Method Summary collapse

Class Method Details

.prepended(base) ⇒ Object

rubocop:disable Metrics/MethodLength



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# File 'lib/ddtrace/contrib/action_view/instrumentation/template_renderer.rb', line 12

def self.prepended(base)
  # rubocop:disable Metrics/BlockLength
  base.class_eval do
    def render_with_datadog(*args, &block)
      # NOTE: This check exists purely for Rails 3.0 compatibility.
      #       The 'if' part can be removed when support for Rails 3.0 is removed.
      if active_datadog_span
        render_without_datadog(*args, &block)
      else
        datadog_tracer.trace(
          Ext::SPAN_RENDER_TEMPLATE,
          span_type: Datadog::Ext::HTTP::TEMPLATE
        ) do |span|
          with_datadog_span(span) { render_without_datadog(*args, &block) }
        end
      end
    end

    def render_template_with_datadog(*args)
      begin
        template = args[0]
        layout_name = args[1]

        # update the tracing context with computed values before the rendering
        template_name = template.try('identifier')
        template_name = Utils.normalize_template_name(template_name)

        if template_name
          active_datadog_span.set_tag(
            Ext::TAG_TEMPLATE_NAME,
            template_name
          )
        end

        if layout_name
          active_datadog_span.set_tag(
            Ext::TAG_LAYOUT,
            layout_name
          )
        end
      rescue StandardError => e
        Datadog::Tracer.log.debug(e.message)
      end

      # execute the original function anyway
      render_template_without_datadog(*args)
    end

    private

    attr_accessor :active_datadog_span

    def datadog_tracer
      Datadog.configuration[:action_view][:tracer]
    end

    def with_datadog_span(span)
      self.active_datadog_span = span
      yield
    ensure
      self.active_datadog_span = nil
    end

    # method aliasing to patch the class
    alias_method :render_without_datadog, :render
    alias_method :render, :render_with_datadog

    alias_method :render_template_without_datadog, :_render_template
    alias_method :_render_template, :render_template_with_datadog
  end
end