June 2018 Update

Task/Dining-philosophers/Kotlin/dining-philosophers.kotlin

@@ -0,0 +1,58 @@
+// Version 1.2.31
+
+import java.util.Random
+import java.util.concurrent.locks.Lock
+import java.util.concurrent.locks.ReentrantLock
+
+val rand = Random()
+
+class Fork(val name: String) {
+    val lock = ReentrantLock()
+
+    fun pickUp(philosopher: String) {
+        lock.lock()
+        println("  $philosopher picked up $name")
+    }
+
+    fun putDown(philosopher: String) {
+        lock.unlock()
+        println("  $philosopher put down $name")
+    }
+}
+
+class Philosopher(val pname: String, val f1: Fork, val f2: Fork) : Thread() {
+    override fun run() {
+        (1..20).forEach {
+            println("$pname is hungry")
+            f1.pickUp(pname)
+            f2.pickUp(pname)
+            println("$pname is eating bite $it")
+            Thread.sleep(rand.nextInt(300) + 100L)
+            f2.putDown(pname)
+            f1.putDown(pname)
+        }
+    }
+}
+
+fun diningPhilosophers(names: List<String>) {
+    val size = names.size
+    val forks = List(size) { Fork("Fork ${it + 1}") }
+    val philosophers = mutableListOf<Philosopher>()
+    names.forEachIndexed { i, n ->
+        var i1 = i
+        var i2 = (i + 1) % size
+        if (i2 < i1) {
+            i1 = i2
+            i2 = i
+        }
+        val p = Philosopher(n, forks[i1], forks[i2])
+        p.start()
+        philosophers.add(p)
+    }
+    philosophers.forEach { it.join() }
+}
+
+fun main(args: Array<String>) {
+    val names = listOf("Aristotle", "Kant", "Spinoza", "Marx", "Russell")
+    diningPhilosophers(names)
+}