Module: NewRelic::Agent::Instrumentation::ControllerInstrumentation

Included in:
Rack
Defined in:
lib/new_relic/agent/instrumentation/controller_instrumentation.rb

Overview

NewRelic instrumentation for controller actions and tasks

This instrumentation is applied to the action controller to collect metrics for every web request.

It can also be used to capture performance information for background tasks and other non-web transactions, including detailed transaction traces and traced errors.

For details on how to instrument background tasks see ClassMethods#add_transaction_tracer and #perform_action_with_newrelic_trace

Instance Method Summary collapse

Instance Method Details

#perform_action_with_newrelic_trace(*args, &block) ⇒ Object

Yield to the given block with NewRelic tracing. Used by default instrumentation on controller actions in Rails and Merb. But it can also be used in custom instrumentation of controller methods and background tasks.

This is the method invoked by instrumentation added by the ClassMethods#add_transaction_tracer.

Here’s a more verbose version of the example shown in ClassMethods#add_transaction_tracer using this method instead of #add_transaction_tracer.

Below is a controller with an invoke_operation action which dispatches to more specific operation methods based on a parameter (very dangerous, btw!). With this instrumentation, the invoke_operation action is ignored but the operation methods show up in New Relic as if they were first class controller actions

MyController < ActionController::Base
  include NewRelic::Agent::Instrumentation::ControllerInstrumentation
  # dispatch the given op to the method given by the service parameter.
  def invoke_operation
    op = params['operation']
    perform_action_with_newrelic_trace(:name => op) do
      send op, params['message']
    end
  end
  # Ignore the invoker to avoid double counting
  newrelic_ignore :only => 'invoke_operation'
end

When invoking this method explicitly as in the example above, pass in a block to measure with some combination of options:

  • :category => :controller indicates that this is a controller action and will appear with all the other actions. This is the default.

  • :category => :task indicates that this is a background task and will show up in New Relic with other background tasks instead of in the controllers list

  • :category => :rack if you are instrumenting a rack middleware call. The :name is optional, useful if you have more than one potential transaction in the #call.

  • :category => :uri indicates that this is a web transaction whose name is a normalized URI, where ‘normalized’ means the URI does not have any elements with data in them such as in many REST URIs.

  • :name => action_name is used to specify the action name used as part of the metric name

  • :params => {...} to provide information about the context of the call, used in transaction trace display, for example: :params => { :account => @account.name, :file => file.name } These are treated similarly to request parameters in web transactions.

Seldomly used options:

  • :force => true indicates you should capture all metrics even if the #newrelic_ignore directive was specified

  • :class_name => aClass.name is used to override the name of the class when used inside the metric name. Default is the current class.

  • :path => metric_path is deprecated in the public API. It allows you to set the entire metric after the category part. Overrides all the other options.

  • :request => Rack::Request#new(env) is used to pass in a request object that may respond to uri and referer.

If a single argument is passed in, it is treated as a metric path. This form is deprecated.



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# File 'lib/new_relic/agent/instrumentation/controller_instrumentation.rb', line 312

def perform_action_with_newrelic_trace(*args, &block)
  NewRelic::Agent::TransactionState.request = newrelic_request(args)

  # Skip instrumentation based on the value of 'do_not_trace' and if
  # we aren't calling directly with a block.
  if !block_given? && do_not_trace?
    # Also ignore all instrumentation in the call sequence
    NewRelic::Agent.disable_all_tracing do
      return perform_action_without_newrelic_trace(*args)
    end
  end

  txn = _start_transaction(block_given? ? args : [])
  begin
    options = { :force => txn.force_flag, :transaction => true }
    return yield if !(NewRelic::Agent.is_execution_traced? || options[:force])
    options[:metric] = true if options[:metric].nil?
    options[:deduct_call_time_from_parent] = true if options[:deduct_call_time_from_parent].nil?
    _, expected_scope = NewRelic::Agent::MethodTracer::TraceExecutionScoped.trace_execution_scoped_header(options, txn.start_time.to_f)

    begin
      NewRelic::Agent::BusyCalculator.dispatcher_start txn.start_time
      if block_given?
        yield
      else
        perform_action_without_newrelic_trace(*args)
      end
    rescue => e
      txn.notice_error(e)
      raise
    end

  ensure
    end_time = Time.now

    txn.freeze_name
    metric_names = Array(recorded_metrics(txn))
    txn_name = metric_names.shift

    NewRelic::Agent::MethodTracer::TraceExecutionScoped.trace_execution_scoped_footer(txn.start_time.to_f, txn_name, metric_names, expected_scope, options, end_time.to_f)
    NewRelic::Agent::BusyCalculator.dispatcher_finish(end_time)
    txn.record_apdex(end_time) unless ignore_apdex?
    txn = Transaction.stop(txn_name, end_time)

    NewRelic::Agent::TransactionState.get.request_ignore_enduser = true if ignore_enduser?
  end
end