I Wanna be A Philosopher

import java.util.concurrent.Semaphore
import kotlin.concurrent.thread

private object SemSys {
    val sem = Semaphore(5)
}

private data class Philosopher(val num: Int) {
    private val name = "Philosopher $num"
    var forks = 0

    private fun thinking() = println("$name has started thinking")

    private fun canEat() = forks == 2

    private fun eat() {
        println("$name has started eating")
        Thread.sleep(1000)
        println("$name has finished eating")
        returnForks()
    }

    fun takeFork() {
        when (forks) {
            0 -> when {
                !SemSys.sem.tryAcquire() -> return
                else -> {
                    forks++
                    if (SemSys.sem.tryAcquire()) forks++
                }
            }

            else -> when {
                !SemSys.sem.tryAcquire() -> return
                else -> forks++
            }
        }

        println("$name has taken fork (now: ${forks})")
        if (canEat()) eat()
    }

    private fun returnForks() {
        SemSys.sem.release(2)
        println("$name has returned forks")
        forks = 0
        thinking()
    }
}

fun main() {
    (1..5).forEach {
        val philosopher = Philosopher(it)

        thread {
            while (true)
                philosopher.takeFork()
        }
    }
}