Scala で ReadWriteLock にローンパターンを使う ref: http://qiita.com/items/2805

LoanPatternLock.scala

object LoanPatternLock {
  import java.util.concurrent.locks.{Lock, ReadWriteLock}

  def lockWith[A <% Lock, B](l: A)(e: => B) = {
    l.lock()
    try e finally l.unlock()
  }

  def readLockWith[A <% ReadWriteLock, B](l: A)(e: => B) =
    lockWith(l.readLock)(e)

  def writeLockWith[A <% ReadWriteLock, B](l: A)(e: => B) =
    lockWith(l.writeLock)(e)
}