AccessLog for Finagle

AccessLog.scala

import java.util.concurrent.Executors
import java.io.{File, FileOutputStream, PrintWriter}

import com.twitter.finagle.{Service, SimpleFilter}
import com.twitter.finagle.http.{Request, Response}
import com.twitter.util.Future

final class AccessLog(file: File) extends SimpleFilter[Request, Response] {
  private[this] final val scheduler = Executors.newSingleThreadExecutor()

  private[this] final def log(r: Request): Unit = {
    scheduler.submit(new Runnable {
      def run(): Unit = {
        val pw = new PrintWriter(new FileOutputStream(file, true)) 
        try pw.println(s"${r.method} ${r.path} [from: ${r.remoteAddress}]") finally pw.close()
      }
    })
  }

  def apply(req: Request, next: Service[Request, Response]): Future[Response] = {
    log(req)
    next(req)
  }
}