Retrying with style

Example.scala

val retryBlock = new Retry[String](6)
import retryBlock.retry

retry {
  doSomething(somePar)
} giveup {
  case e: Exception => handleException(e)
}

Retry.scala

import scala.math._
import scala.util.control.Exception._

class Retry[T](maxRetry: Int) {
  private var retryCount = 0
  private var block: () => T = _
  def retry(op: => T): Retry[T] = {
    block = () => {
      try {
        op
      } catch {
        case t: Throwable =>
          retryCount += 1
          if (retryCount == maxRetry) {
            throw t
          } else {
            val interval = round(pow(2, retryCount)) * 100;
            Thread.sleep(interval)
            block()
          }
      }
    }
    this
  }

  def giveup(handler: => Catcher[T]): T = {
    catching(handler) { block() }
  }
}

TestRetry.scala

import org.specs2.mutable._

class TestRetry extends Specification {

  "retry" should {
    "retry six times" in {
      val retryTimes = 6
      val r = new Retry[String](retryTimes)
      import r.retry

      var count = 0
      val start = System.currentTimeMillis
      var result =
        retry {
          count += 1
          throw new Exception("expected_exception")
        } giveup {
          case e: Exception => "OK"
        }
      (System.currentTimeMillis - start) must be_>=(6200L)
      count must_== retryTimes
      result must beEqualTo("OK")
    }
  }
}