リトライハンドラーの殴り書き

readme.md

• 1秒後, 5秒後, 15秒後, 60秒後 みたいなリトライがしたかったので interval に Stream[Int] を渡せるようにしてみた。
• 無限 Stream 渡したら無限 retry もできるね。

tailrec.scala

import scala.util.control.Exception.allCatch

object RetryUtil {

  case class RetryException(throwables: List[Throwable]) extends Exception

  def retry[T](retryLimit: Int, retryInterval: Int, shouldCatch: Throwable => Boolean)(f: => T): T =
    retry(Stream.fill(retryLimit)(retryInterval), shouldCatch)(f)

  def retry[T](intervals: Stream[Int], shouldCatch: Throwable => Boolean)(f: => T): T = {
    @annotation.tailrec
    def _retry(_intervals: Stream[Int], errors: List[Throwable]): T = {
      allCatch.either(f) match {
        case Right(r) => r
        case Left(e) =>
          if (shouldCatch(e)) {
            _intervals match {
              case head #:: tail =>
                Thread.sleep(head)
                _retry(tail, e :: errors)
              case _ => throw RetryException(e :: errors)
            }
          } else throw e
      }
    }
    _retry(intervals, Nil)
  }

}

z_sample.scala

scala> RetryUtil.retry(1000 #:: 3000 #:: 10000 #:: Stream.empty[Int], {_ => true}) {
     |   println(new java.util.Date)
     |   throw new RuntimeException("hoge")
     | }
Thu Jul 05 02:58:24 JST 2012
Thu Jul 05 02:58:25 JST 2012
Thu Jul 05 02:58:28 JST 2012
Thu Jul 05 02:58:38 JST 2012
RetryUtil$RetryException
        at RetryUtil$._retry$1(<console>:30)
        at RetryUtil$.retry(<console>:35)
        at .<init>(<console>:14)
        at .<clinit>(<console>)
        at .<init>(<console>:11)
        at .<clinit>(<console>)
        at $print(<console>)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.call(IMain.scala:704)
        at scala.tools.nsc.interpreter.IMain$Request$$anonfun$14.apply(IMain.scala:920)
        at scala.tools.nsc.interpreter.Line$$anonfun$1.apply$mcV$sp(Line.scala:43)
        at scala.tools.nsc.io.package$$anon$2.run(package.scala:25)
        at java.lang.Thread.run(Thread.java:722)