gistfile1.scala

  def doSync[F](f: => F): F = S.session match {
    case Full(s) => {
      // lock the session while the Var-specific lock object is found/created
      val lockName = name + VarConstants.lockSuffix
      val lockObj: Object = s.synchronized {
        localGet(s, lockName) match {
          case Full(lock: Object) => lock
          case _ => val lock = new Object
            localSet(s, lockName, null)
            lock
        }
      }

      // execute the query in the scope of the lock obj
      lockObj.synchronized {
        f
      }
    }

    case _ => f
  }