Class: ScoutApm::Instant::DevTraceResponseManipulator

Inherits:
Object
  • Object
show all
Defined in:
lib/scout_apm/instant/middleware.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(env, rack_response) ⇒ DevTraceResponseManipulator

Returns a new instance of DevTraceResponseManipulator.



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# File 'lib/scout_apm/instant/middleware.rb', line 69

def initialize(env, rack_response)
  @env = env
  @rack_response = rack_response

  @rack_status = rack_response[0]
  @rack_headers = rack_response[1]
  @rack_body = rack_response[2]
end

Instance Attribute Details

#envObject (readonly)

Returns the value of attribute env.



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# File 'lib/scout_apm/instant/middleware.rb', line 67

def env
  @env
end

#rack_bodyObject (readonly)

Returns the value of attribute rack_body.



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# File 'lib/scout_apm/instant/middleware.rb', line 66

def rack_body
  @rack_body
end

#rack_headersObject (readonly)

Returns the value of attribute rack_headers.



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# File 'lib/scout_apm/instant/middleware.rb', line 66

def rack_headers
  @rack_headers
end

#rack_responseObject (readonly)

Returns the value of attribute rack_response.



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# File 'lib/scout_apm/instant/middleware.rb', line 65

def rack_response
  @rack_response
end

#rack_statusObject (readonly)

Returns the value of attribute rack_status.



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# File 'lib/scout_apm/instant/middleware.rb', line 66

def rack_status
  @rack_status
end

Instance Method Details

#adjust_ajax_headerObject



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# File 'lib/scout_apm/instant/middleware.rb', line 130

def adjust_ajax_header
  rack_headers['X-scoutapminstant'] = payload
end

#adjust_html_responseObject



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# File 'lib/scout_apm/instant/middleware.rb', line 134

def adjust_html_response
  case true
  when older_rails_response? then adjust_older_rails_response
  when newer_rails_response? then adjust_newer_rails_response
  when rack_proxy_response? then  adjust_rack_proxy_response
  else
    # No action taken, we only adjust if we know exactly what we have.
  end
end

#adjust_newer_rails_responseObject

Preserve the ActionDispatch::Response object we’re working with



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# File 'lib/scout_apm/instant/middleware.rb', line 166

def adjust_newer_rails_response
  logger.debug("DevTrace: in middleware, dev_trace is active, and response has a (newer) body. This appears to be an HTML page and an ActionDispatch::Response. Path=#{path}; ContentType=#{content_type}")
  @rack_body = [ html_manipulator.res ]
end

#adjust_older_rails_responseObject



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# File 'lib/scout_apm/instant/middleware.rb', line 160

def adjust_older_rails_response
  logger.debug("DevTrace: in middleware, dev_trace is active, and response has a (older) body. This appears to be an HTML page and an ActionDispatch::Response. Path=#{path}; ContentType=#{content_type}")
  rack_body.body = [ html_manipulator.res ]
end

#adjust_rack_proxy_responseObject



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# File 'lib/scout_apm/instant/middleware.rb', line 171

def adjust_rack_proxy_response
  logger.debug("DevTrace: in middleware, dev_trace is active, and response has a body. This appears to be an HTML page and an Rack::BodyProxy. Path=#{path}; ContentType=#{content_type}")
  @rack_body = [ html_manipulator.res ]
  @rack_headers.delete("Content-Length")
end

#ajax_request?Boolean

Returns:

  • (Boolean)


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# File 'lib/scout_apm/instant/middleware.rb', line 194

def ajax_request?
  env['HTTP_X_REQUESTED_WITH'] == 'XMLHttpRequest' || content_type.include?("application/json")
end

#apm_hostObject



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# File 'lib/scout_apm/instant/middleware.rb', line 222

def apm_host
  ScoutApm::Agent.instance.context.config.value("direct_host")
end

#callObject



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# File 'lib/scout_apm/instant/middleware.rb', line 78

def call
  return rack_response unless preconditions_met?

  if ajax_request?
    ScoutApm::Agent.instance.context.logger.debug("DevTrace: in middleware, dev_trace is active, and response has a body. This is either AJAX or JSON. Path=#{path}; ContentType=#{content_type}")
    adjust_ajax_header
  else
    adjust_html_response
  end

  rebuild_rack_response
end

#content_typeObject



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# File 'lib/scout_apm/instant/middleware.rb', line 206

def content_type
  rack_headers['Content-Type']
end

#dev_trace_disabled?Boolean

Returns:

  • (Boolean)


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# File 'lib/scout_apm/instant/middleware.rb', line 118

def dev_trace_disabled?
  ! ScoutApm::Agent.instance.context.config.value('dev_trace')
end

#development_asset?Boolean

Returns:

  • (Boolean)


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# File 'lib/scout_apm/instant/middleware.rb', line 198

def development_asset?
  !rack_body.respond_to?(:body)
end

#html_manipulatorObject



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# File 'lib/scout_apm/instant/middleware.rb', line 177

def html_manipulator
  @html_manipulator ||=
    begin
      page = ScoutApm::Instant::Page.new(rack_body.body)

      # This monkey-patches XMLHttpRequest. It could possibly be part of the main scout_instant.js too. Putting it here so it runs as soon as possible.
      page.add_to_head(ScoutApm::Instant::Util.read_asset("xmlhttp_instrumentation.html"))

      # Add a link to CSS, then JS
      page.add_to_head("<link href='#{apm_host}/instant/scout_instant.css?cachebust=#{Time.now.to_i}' media='all' rel='stylesheet' />")
      page.add_to_body("<script src='#{apm_host}/instant/scout_instant.js?cachebust=#{Time.now.to_i}'></script>")
      page.add_to_body("<script>var scoutInstantPageTrace=#{payload};window.scoutInstant=window.scoutInstant('#{apm_host}', scoutInstantPageTrace)</script>")

      page
    end
end

#loggerObject

APM Helpers & Shorthands #



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# File 'lib/scout_apm/instant/middleware.rb', line 214

def logger
  ScoutApm::Agent.instance.context.logger
end

#newer_rails_response?Boolean

Returns:

  • (Boolean)


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# File 'lib/scout_apm/instant/middleware.rb', line 150

def newer_rails_response?
  if defined?(ActionDispatch::Response::RackBody)
    return true if rack_body.is_a?(ActionDispatch::Response::RackBody)
  end
end

#older_rails_response?Boolean

Returns:

  • (Boolean)


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# File 'lib/scout_apm/instant/middleware.rb', line 144

def older_rails_response?
  if defined?(ActionDispatch::Response)
    return true if rack_body.is_a?(ActionDispatch::Response)
  end
end

#pathObject



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# File 'lib/scout_apm/instant/middleware.rb', line 202

def path
  env['PATH_INFO']
end

#payloadObject



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# File 'lib/scout_apm/instant/middleware.rb', line 235

def payload
  @payload ||=
    begin
       = {
        :app_root      => ScoutApm::Agent.instance.context.environment.root.to_s,
        :unique_id     => env['action_dispatch.request_id'], # note, this is a different unique_id than what "normal" payloads use
        :agent_version => ScoutApm::VERSION,
        :platform      => "ruby",
      }

      hash = ScoutApm::Serializers::PayloadSerializerToJson.
        rearrange_slow_transaction(trace).
        merge!(:metadata => )
      ScoutApm::Serializers::PayloadSerializerToJson.jsonify_hash(hash)
    end
end

#preconditions_met?Boolean

Precondition checking #

Returns:

  • (Boolean)


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# File 'lib/scout_apm/instant/middleware.rb', line 95

def preconditions_met?
  if dev_trace_disabled?
    logger.debug("DevTrace: isn't activated via config. Try: SCOUT_DEV_TRACE=true rails server")
    return false
  end

  # Don't attempt to instrument assets.
  # Don't log this case, since it would be very noisy
  logger.debug("DevTrace: dev asset ignored") and return false if development_asset?

  # If we didn't have a tracked_request object, or we explicitly ignored
  # this request, don't do any work.
  logger.debug("DevTrace: no tracked request") and return false if tracked_request.nil? || tracked_request.ignoring_request?

  # If we didn't get a trace, we can't show a trace...
  if trace.nil?
    logger.debug("DevTrace: in middleware, dev_trace is active, and response has a body, but no trace was found. Path=#{path}; ContentType=#{content_type}")
    return false
  end

  true
end

#rack_proxy_response?Boolean

Returns:

  • (Boolean)


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# File 'lib/scout_apm/instant/middleware.rb', line 156

def rack_proxy_response?
  rack_body.is_a?(::Rack::BodyProxy)
end

#rebuild_rack_responseObject

Response Injection #



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# File 'lib/scout_apm/instant/middleware.rb', line 126

def rebuild_rack_response
  [rack_status, rack_headers, rack_body]
end

#traceObject



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# File 'lib/scout_apm/instant/middleware.rb', line 226

def trace
  @trace ||=
    begin
      layer_finder = LayerConverters::FindLayerByType.new(tracked_request)
      converter = LayerConverters::SlowRequestConverter.new(ScoutApm::Agent.instance.context, tracked_request, layer_finder, ScoutApm::FakeStore.new)
      converter.call
    end
end

#tracked_requestObject



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# File 'lib/scout_apm/instant/middleware.rb', line 218

def tracked_request
  @tracked_request ||= ScoutApm::RequestManager.lookup
end