instrumenting rabl rendering on newrelic rpm : config/initializers/rpm_instrumentation.rb

rpm_instrumentation.rb

require 'new_relic/agent/method_tracer'
require 'grape-rabl/formatter'
# 0.3.1: Grape::Formatter::Rabl.call, master: Grape::Rabl::Formatter#render
Grape::Formatter::Rabl.class_eval do # class_eval creates instance methods
  class << self
    include ::NewRelic::Agent::MethodTracer

    # https://github.com/ruby-grape/grape-rabl/blob/v0.3.1/lib/grape-rabl/formatter.rb
    def call_with_newrelic(object, env)
      rabl_path = env['api.tilt.rabl'] || env['api.endpoint'].options[:route_options][:rabl]
      path = rabl_path ? "RABL #{rabl_path}" : 'JSON'
      ::NewRelic::Agent::MethodTracer.trace_execution_scoped("View/#{path}") do
        call_without_newrelic(object, env)
      end
    end

    alias_method :call_without_newrelic, :call
    alias_method :call, :call_with_newrelic
  end
end