dining philosophers

dining.sc

import com.twitter.concurrent.Offer
import com.twitter.util.{Await, Future}
import scala.concurrent.duration._
import scala.util.Random
import scala.collection.mutable.Seq

val deadline = 3 seconds fromNow
val r = new Random()
val numPhilosophers = 3


case class Spoon(toLeftOf: Int, var taken:Boolean)
case class Philosopher(n: Int, var eating:Boolean,var hungry:Boolean, var got:Seq[Boolean] = scala.collection.mutable.Seq((0 until numPhilosophers):_*).map(_ => false),
                       thinkTime: Int, eatTime: Int)

def whichSpoons(p:Philosopher, numPhilosophers:Int) : Seq[Int] = {
  Seq(p.n, (p.n + 1) % numPhilosophers  )
}
def whichPhilosophers(s :Spoon, numPhilosophers:Int) : Seq[Int] = {
  Seq(s.toLeftOf, (s.toLeftOf - 1 + numPhilosophers) % numPhilosophers  )
}

def run(thinkTime: Int, eatTime:Int, runforTime:Int):Unit = {
  val spoons = (0 until numPhilosophers).map(i => new Spoon(i, taken = false))

  (0 until numPhilosophers).par.foreach((x: Int) => {
    val p = new Philosopher(x, false,false, thinkTime = thinkTime, eatTime = eatTime)
    while(deadline.hasTimeLeft) {
      //Thread.sleep(r.nextInt(100))
      println("phil " + p.n  + " is hungry")
      var spoonsNotTaken:Boolean = whichSpoons(p, numPhilosophers).map( i => !(spoons(i).taken)).reduce(_&_)
      if(spoonsNotTaken){
        for( s <- whichSpoons(p, numPhilosophers).map(i => spoons(i))) {
          if( !s.taken){
            println("phil " + p.n  + " taking sppon" + s.toLeftOf)
            s.taken = true
            p.got(s.toLeftOf) = true
          }
          Thread.sleep(500) // to get deadlock, catch breath after first spoon
        }
      } else println("phil " + p.n  + "didn't see 2")

      var gotSpoons = whichSpoons(p, numPhilosophers).map( i => p.got(i)).reduce(_&_)
      if(gotSpoons) {
        p.eating = true
        println("phil " + p.n  + " eats for " + p.eatTime + " s")
        Thread.sleep(p.eatTime)
        whichSpoons(p, numPhilosophers).map(i => {
          spoons(i).taken = false
        })
        p.hungry = false
        Thread.sleep(p.thinkTime)
      } else p.hungry = true
    }
  })
}
run(3,5,5)