LongMaxUpdater.scala

import java.util.concurrent.atomic.AtomicLong
import scala.annotation.tailrec

class LongMaxUpdater(value:AtomicLong) {
  def update(newMax:Long):Long = {
    @tailrec def compare():Long = {
      val currentMax = value.get()
      if(newMax > currentMax) {
        if (!value.compareAndSet(currentMax, newMax)) compare() 
        else newMax
      } else currentMax
    }
    compare()
  }

  def get():Long = value.get()
  def set(newValue:Long):Long = value.getAndSet(newValue)
}


object LongMaxUpdater {
  def apply(): LongMaxUpdater = new LongMaxUpdater(new AtomicLong(0L))
}