Using New Relic with Finagle is a pain

NewRelicFinagleFilter.scala

import org.apache.thrift.protocol.TProtocolFactory
import com.twitter.finagle.{Service, SimpleFilter}
import com.twitter.util.{Duration, Time}
import org.apache.thrift.transport.TMemoryInputTransport
import com.newrelic.api.agent.{Response, Request, NewRelic, Trace}
import java.util.Collections

class NewRelicFinagleFilter(protocolFactory:TProtocolFactory) extends SimpleFilter[Array[Byte], Array[Byte]] {

  def apply(request: Array[Byte], service: Service[Array[Byte], Array[Byte]]) = {
    val start = Time.now
    val inputTransport = new TMemoryInputTransport(request)
    val iprot = protocolFactory.getProtocol(inputTransport)
    val msg = iprot.readMessageBegin()

    service(request)
      .onSuccess { _ =>
      val duration = Time.now - start
      println(msg.name, duration, "ok")
      reportOk(msg.name, duration)
    }
      .onFailure { e =>
      val duration = Time.now - start
      println(msg.name, duration, e.getClass.getName)
      reportErr(msg.name, duration, e)
    }
  }

  @Trace(dispatcher = true)
  def reportOk(uri:String, duration:Duration) {
    NewRelic.setTransactionName(null, uri)
    NewRelic.setRequestAndResponse(Req(uri), OK)
    NewRelic.recordResponseTimeMetric(uri, duration.inMillis)
  }

  @Trace(dispatcher = true)
  def reportErr(uri:String, duration:Duration, e:Throwable) {
    NewRelic.setTransactionName(null, uri)
    NewRelic.setRequestAndResponse(Req(uri), Error(e))
    NewRelic.noticeError(e)
    NewRelic.recordResponseTimeMetric(uri, duration.inMillis)
  }

  case class Req(uri:String) extends Request {
    def getRequestURI = uri
    def getHeader(p1: String) = null
    def getRemoteUser = null
    def getParameterNames = Collections.enumeration(Collections.EMPTY_LIST)
    def getParameterValues(p1: String) = Array[String]()
    def getAttribute(p1: String) = null
  }

  sealed abstract class R extends Response {
    def setHeader(p1: String, p2: String) {}
  }

  object OK extends R {
    def getStatus = 200
    def getStatusMessage = null
  }

  case class Error(e:Throwable) extends R {
    def getStatus = 500
    def getStatusMessage = e.getClass.getName
  }
}