SlidingWindowMap

SlidingWindowMap.scala

class SlidingWindowMap(keys: Set[String], maxCount: Int, periodMs: Int) {
  val times = collection.mutable.Map(keys.map(k => (k, Vector[Long]())).toList:_*)
  def nextKey: Option[String] = {
    val now = System.currentTimeMillis
    this.synchronized {
      val key = times.find(_._2.dropWhile(_ < now - periodMs).size < maxCount).map(_._1)
      key.foreach { k => times(k) = times(k).dropWhile(_ < now - periodMs) :+ now }
      key
    }
  }
}