September 2017 Update

Task/Time-a-function/Kotlin/time-a-function.kotlin

@@ -0,0 +1,24 @@
+// version 1.1.2
+// need to enable runtime assertions with JVM -ea option
+
+import java.lang.management.ManagementFactory
+import java.lang.management.ThreadMXBean
+
+fun countTo(x: Int) {
+    println("Counting...");
+    (1..x).forEach {}
+    println("Done!")
+}
+
+fun main(args: Array<String>) {
+    val counts = intArrayOf(100_000_000, 1_000_000_000)
+    val threadMX = ManagementFactory.getThreadMXBean()
+    assert(threadMX.isCurrentThreadCpuTimeSupported)
+    threadMX.isThreadCpuTimeEnabled = true
+    for (count in counts) {
+        val start = threadMX.currentThreadCpuTime
+        countTo(count)
+        val end = threadMX.currentThreadCpuTime
+        println("Counting to $count takes ${(end-start)/1000000}ms")
+    }
+}