Implement the padlock

padlock-impl/src/main/java/com/cleverthis/interview/padlock/Utils.java

@@ -0,0 +1,22 @@
+package com.cleverthis.interview.padlock;
+
+class Utils {
+    /**
+     * Ensure we will wait a given amount of time even if there are interruptions.
+     *
+     * @param millis The time you want to sleep, measure in millisecond.
+     */
+    public static void ensureSleep(long millis) {
+        long endTime = System.currentTimeMillis() + millis;
+        while (endTime > System.currentTimeMillis()) {
+            try {
+                //noinspection BusyWait
+                Thread.sleep(endTime - System.currentTimeMillis());
+            } catch (InterruptedException e) {
+                // do nothing when interrupted, will re-sleep in next loop
+            } catch (IllegalArgumentException e) {
+                break;
+            }
+        }
+    }
+}